refactor(codemode): type program values as Value

refactor(codemode): let each built-in object answer for itself
fix(codemode): locate failures in the submitted source (#50197 )
2026-09-21 08:07:34 +00:00 · 2026-09-20 21:06:11 -05:00 · 2026-09-20 21:05:45 -05:00 · 2026-09-20 20:47:54 -05:00 · 2026-09-20 22:57:20 +00:00 · 2026-09-20 19:15:37 +00:00
379 changed files with 8482 additions and 4109 deletions
@@ -32,7 +32,7 @@
    },
    "packages/ai": {
      "name": "@opencode/ai",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@aws-sdk/credential-providers": "3.1057.0",
        "@opencode/schema": "workspace:*",
@@ -54,7 +54,7 @@
    },
    "packages/app": {
      "name": "@opencode/app",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@corvu/drawer": "catalog:",
        "@dnd-kit/abstract": "0.5.0",
@@ -87,7 +87,6 @@
        "effect": "catalog:",
        "fuzzysort": "catalog:",
        "ghostty-web": "github:anomalyco/ghostty-web#83c0a07b8628b748aed073b232cb4b52a6ca11c1",
-        "luxon": "catalog:",
        "qr-scanner": "1.4.2",
        "remeda": "catalog:",
        "solid-js": "catalog:",
@@ -100,7 +99,6 @@
        "@sentry/vite-plugin": "catalog:",
        "@tailwindcss/vite": "4.3.3",
        "@types/bun": "catalog:",
-        "@types/luxon": "catalog:",
        "@types/node": "catalog:",
        "@typescript/native-preview": "catalog:",
        "diff": "catalog:",
@@ -113,7 +111,7 @@
    },
    "packages/cli": {
      "name": "@opencode/cli",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "bin": {
        "opencode2": "./bin/opencode2.cjs",
      },
@@ -177,7 +175,7 @@
    },
    "packages/client": {
      "name": "@opencode/client",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@opencode/protocol": "workspace:*",
        "@opencode/schema": "workspace:*",
@@ -203,11 +201,10 @@
    },
    "packages/codemode": {
      "name": "@opencode/codemode",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "acorn": "8.15.0",
        "effect": "catalog:",
-        "typescript": "catalog:",
      },
      "devDependencies": {
        "@tsconfig/bun": "catalog:",
@@ -217,7 +214,7 @@
    },
    "packages/console/app": {
      "name": "@opencode/console-app",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@cloudflare/vite-plugin": "1.15.2",
        "@ibm/plex": "6.4.1",
@@ -253,7 +250,7 @@
    },
    "packages/console/core": {
      "name": "@opencode/console-core",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@aws-sdk/client-sts": "3.782.0",
        "@jsx-email/render": "1.1.1",
@@ -280,7 +277,7 @@
    },
    "packages/console/function": {
      "name": "@opencode/console-function",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@openauthjs/openauth": "0.0.0-20250322224806",
        "@opencode/console-core": "workspace:*",
@@ -297,7 +294,7 @@
    },
    "packages/console/mail": {
      "name": "@opencode/console-mail",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@jsx-email/all": "2.2.3",
        "@jsx-email/cli": "1.4.3",
@@ -321,7 +318,7 @@
    },
    "packages/console/support": {
      "name": "@opencode/console-support",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@cloudflare/vite-plugin": "1.15.2",
        "@opencode/console-core": "workspace:*",
@@ -341,7 +338,7 @@
    },
    "packages/core": {
      "name": "@opencode/core",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@ai-sdk/cohere": "3.0.27",
        "@ai-sdk/gateway": "3.0.104",
@@ -409,14 +406,12 @@
    },
    "packages/desktop": {
      "name": "@opencode/desktop",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@zip.js/zip.js": "2.7.62",
        "electron-context-menu": "4.1.2",
        "electron-log": "^5",
-        "electron-store": "11.0.2",
        "electron-updater": "6.8.9",
-        "electron-window-state": "^5.0.3",
        "lighthouse": "13.4.1",
      },
      "devDependencies": {
@@ -460,7 +455,7 @@
    },
    "packages/enterprise": {
      "name": "@opencode/enterprise",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@hono/standard-validator": "catalog:",
        "@opencode-ai/sdk": "1.18.21",
@@ -497,7 +492,7 @@
    },
    "packages/function": {
      "name": "@opencode/function",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@octokit/auth-app": "8.0.1",
        "@octokit/rest": "catalog:",
@@ -513,7 +508,7 @@
    },
    "packages/http-recorder": {
      "name": "@opencode/http-recorder",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@effect/platform-node-shared": "4.0.0-rc.112",
      },
@@ -532,7 +527,7 @@
    },
    "packages/httpapi-codegen": {
      "name": "@opencode/httpapi-codegen",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "effect": "catalog:",
        "prettier": "3.6.2",
@@ -545,7 +540,7 @@
    },
    "packages/latex": {
      "name": "@opencode/latex",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@opencode/plugin": "workspace:*",
        "@opentui/core": "catalog:",
@@ -559,7 +554,7 @@
    },
    "packages/merman": {
      "name": "@opencode/merman",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@opencode/plugin": "workspace:*",
        "@opentui/core": "catalog:",
@@ -574,7 +569,7 @@
    },
    "packages/plugin": {
      "name": "@opencode/plugin",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@ai-sdk/provider": "3.0.8",
        "@opencode/ai": "workspace:*",
@@ -613,7 +608,7 @@
    },
    "packages/plugin-browser": {
      "name": "@opencode/plugin-browser",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@opencode/plugin": "workspace:*",
        "@opencode/schema": "workspace:*",
@@ -643,7 +638,7 @@
    },
    "packages/protocol": {
      "name": "@opencode/protocol",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@opencode/schema": "workspace:*",
        "effect": "catalog:",
@@ -658,7 +653,7 @@
    },
    "packages/schema": {
      "name": "@opencode/schema",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@standard-schema/spec": "catalog:",
        "effect": "catalog:",
@@ -682,7 +677,7 @@
    },
    "packages/sdk": {
      "name": "@opencode/sdk",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@opencode/client": "workspace:*",
        "@opencode/core": "workspace:*",
@@ -703,7 +698,7 @@
    },
    "packages/server": {
      "name": "@opencode/server",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@effect/platform-node": "catalog:",
        "@effect/platform-node-shared": "catalog:",
@@ -725,7 +720,7 @@
    },
    "packages/session-ui": {
      "name": "@opencode/session-ui",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@kobalte/core": "catalog:",
        "@opencode/client": "workspace:*",
@@ -760,7 +755,7 @@
    },
    "packages/simulation": {
      "name": "@opencode/simulation",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@opencode/ai": "workspace:*",
        "@opencode/core": "workspace:*",
@@ -780,7 +775,7 @@
    },
    "packages/stats/app": {
      "name": "@opencode/stats-app",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@ibm/plex": "6.4.1",
        "@kobalte/core": "catalog:",
@@ -814,7 +809,7 @@
    },
    "packages/stats/core": {
      "name": "@opencode/stats-core",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@aws-sdk/client-athena": "3.933.0",
        "@planetscale/database": "1.19.0",
@@ -833,7 +828,7 @@
    },
    "packages/stats/server": {
      "name": "@opencode/stats-server",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@aws-sdk/client-firehose": "3.933.0",
        "@effect/platform-node": "catalog:",
@@ -879,7 +874,7 @@
    },
    "packages/theme": {
      "name": "@opencode/theme",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@opentui/core": "catalog:",
        "effect": "catalog:",
@@ -893,7 +888,7 @@
    },
    "packages/tui": {
      "name": "@opencode/tui",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@opencode/client": "workspace:*",
        "@opencode/core": "workspace:*",
@@ -928,7 +923,7 @@
    },
    "packages/ui": {
      "name": "@opencode/ui",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@kobalte/core": "catalog:",
        "@pierre/diffs": "catalog:",
@@ -963,7 +958,7 @@
    },
    "packages/util": {
      "name": "@opencode/util",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@effect/opentelemetry": "catalog:",
        "@effect/platform-node": "catalog:",
@@ -996,7 +991,7 @@
    },
    "packages/web": {
      "name": "@opencode/web",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "@astrojs/cloudflare": "12.6.3",
        "@astrojs/markdown-remark": "6.3.1",
@@ -1037,7 +1032,7 @@
    },
    "services/update": {
      "name": "@opencode/update",
-      "version": "2.0.8",
+      "version": "2.0.11",
      "dependencies": {
        "jose": "6.0.11",
        "semver": "catalog:",
@@ -3343,8 +3338,6 @@

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@@ -3639,8 +3632,6 @@

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@@ -3779,8 +3770,6 @@

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@@ -4735,8 +4718,6 @@

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@@ -5491,8 +5472,6 @@

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-
    "tailwindcss": ["tailwindcss@4.3.3", "", {}, "sha512-gOhV3P7ufE62QDGg1zVaTgCR+EtPv92k2nIhVcVKcLmxT1sUBsQGhnZj175j+MqRt4zLF7ic+sCYjfhxMxj7YQ=="],

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@@ -5617,8 +5596,6 @@

    "ufo": ["ufo@1.6.4", "", {}, "sha512-JFNbkD1Svwe0KvGi8GOeLcP4kAWQ609twvCdcHxq1oSL8svv39ZuSvajcD8B+5D0eL4+s1Is2D/O6KN3qcTeRA=="],

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-
    "ulid": ["ulid@3.0.1", "", { "bin": { "ulid": "dist/cli.js" } }, "sha512-dPJyqPzx8preQhqq24bBG1YNkvigm87K8kVEHCD+ruZg24t6IFEFv00xMWfxcC4djmFtiTLdFuADn4+DOz6R7Q=="],

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@@ -6445,10 +6422,6 @@

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-    "conf/dot-prop": ["dot-prop@10.2.0", "", { "dependencies": { "type-fest": "^5.0.0" } }, "sha512-BTJ9aZYL3vCfZlZOBLy9v8TUqWGQ0pzFnygKwFZt5udj6viBoFIBviKPUoZLDCPn1FoXffv6McQFDenrm5Krfw=="],
-
-    "conf/env-paths": ["env-paths@3.0.0", "", {}, "sha512-dtJUTepzMW3Lm/NPxRf3wP4642UWhjL2sQxc+ym2YMj1m/H2zDNQOlezafzkHwn6sMstjHTwG6iQQsctDW/b1A=="],
-
    "config-chain/ini": ["ini@1.3.8", "", {}, "sha512-JV/yugV2uzW5iMRSiZAyDtQd+nxtUnjeLt0acNdw98kKLrvuRVyB80tsREOE7yvGVgalhZ6RNXCmEHkUKBKxew=="],

    "configstore/dot-prop": ["dot-prop@9.0.0", "", { "dependencies": { "type-fest": "^4.18.2" } }, "sha512-1gxPBJpI/pcjQhKgIU91II6Wkay+dLcN3M6rf2uwP8hRur3HtQXjVrdAK3sjC0piaEuxzMwjXChcETiJl47lAQ=="],
@@ -6489,8 +6462,6 @@

    "electron-publish/mime": ["mime@2.6.0", "", { "bin": { "mime": "cli.js" } }, "sha512-USPkMeET31rOMiarsBNIHZKLGgvKc/LrjofAnBlOttf5ajRvqiRA8QsenbcooctK6d6Ts6aqZXBA+XbkKthiQg=="],

-    "electron-store/type-fest": ["type-fest@5.8.0", "", { "dependencies": { "tagged-tag": "^1.0.0" } }, "sha512-YGYEVz3Fm5iy/AybuA0oyNFq7H4CgQNfRp/qfe8nurE1kuCeNm3/vfm9X4Mtl+qLyaKJUh5xrFZwogr41SMjYA=="],
-
    "electron-updater/js-yaml": ["js-yaml@4.3.1", "", { "dependencies": { "argparse": "^2.0.1" }, "bin": { "js-yaml": "bin/js-yaml.js" } }, "sha512-CY6crGq313MX8GkwvB7tzgp99vjQxY1++5y10/BKN/GUfHqWaOGQMNZkBvqSzsZKWk/ijwHlWzzkLulsGHhjWQ=="],

    "electron-updater/semver": ["semver@7.7.4", "", { "bin": { "semver": "bin/semver.js" } }, "sha512-vFKC2IEtQnVhpT78h1Yp8wzwrf8CM+MzKMHGJZfBtzhZNycRFnXsHk6E5TxIkkMsgNS7mdX3AGB7x2QM2di4lA=="],
@@ -6521,8 +6492,6 @@

    "form-data/mime-types": ["mime-types@2.1.35", "", { "dependencies": { "mime-db": "1.52.0" } }, "sha512-ZDY+bPm5zTTF+YpCrAU9nK0UgICYPT0QtT1NZWFv4s++TNkcgVaT0g6+4R2uI4MjQjzysHB1zxuWL50hzaeXiw=="],

-    "fs-extra/jsonfile": ["jsonfile@6.2.1", "", { "dependencies": { "universalify": "^2.0.0" }, "optionalDependencies": { "graceful-fs": "^4.1.6" } }, "sha512-zwOTdL3rFQ/lRdBnntKVOX6k5cKJwEc1HdilT71BWEu7J41gXIB2MRp+vxduPSwZJPWBxEzv4yH1wYLJGUHX4Q=="],
-
    "gaxios/node-fetch": ["node-fetch@3.3.2", "", { "dependencies": { "data-uri-to-buffer": "^4.0.0", "fetch-blob": "^3.1.4", "formdata-polyfill": "^4.0.10" } }, "sha512-dRB78srN/l6gqWulah9SrxeYnxeddIG30+GOqK/9OlLVyLg3HPnr6SqOWTWOXKRwC2eGYCkZ59NNuSgvSrpgOA=="],

    "gcp-metadata/gaxios": ["gaxios@7.1.3", "", { "dependencies": { "extend": "^3.0.2", "https-proxy-agent": "^7.0.1", "node-fetch": "^3.3.2", "rimraf": "^5.0.1" } }, "sha512-YGGyuEdVIjqxkxVH1pUTMY/XtmmsApXrCVv5EU25iX6inEPbV+VakJfLealkBtJN69AQmh1eGOdCl9Sm1UP6XQ=="],
@@ -6925,18 +6894,12 @@

    "@electron/asar/minimatch/brace-expansion": ["brace-expansion@1.1.18", "", { "dependencies": { "balanced-match": "^1.0.0", "concat-map": "0.0.1" } }, "sha512-Edep/X9fGqVNmzKBVsDYIOtD+z1tuezV70LBjdCst9Tqu76lsnvRiZ6oTic1n+/BIwX6QDGAO94PN4N2SADvtw=="],

-    "@electron/fuses/fs-extra/jsonfile": ["jsonfile@6.2.1", "", { "dependencies": { "universalify": "^2.0.0" }, "optionalDependencies": { "graceful-fs": "^4.1.6" } }, "sha512-zwOTdL3rFQ/lRdBnntKVOX6k5cKJwEc1HdilT71BWEu7J41gXIB2MRp+vxduPSwZJPWBxEzv4yH1wYLJGUHX4Q=="],
+    "@electron/get/fs-extra/jsonfile": ["jsonfile@4.0.0", "", { "optionalDependencies": { "graceful-fs": "^4.1.6" } }, "sha512-m6F1R3z8jjlf2imQHS2Qez5sjKWQzbuuhuJ/FKYFRZvPE3PuHcSMVZzfsLhGVOkfd20obL5SWEBew5ShlquNxg=="],

    "@electron/get/fs-extra/universalify": ["universalify@0.1.2", "", {}, "sha512-rBJeI5CXAlmy1pV+617WB9J63U6XcazHHF2f2dbJix4XzpUF0RS3Zbj0FGIOCAva5P/d/GBOYaACQ1w+0azUkg=="],

-    "@electron/notarize/fs-extra/jsonfile": ["jsonfile@6.2.1", "", { "dependencies": { "universalify": "^2.0.0" }, "optionalDependencies": { "graceful-fs": "^4.1.6" } }, "sha512-zwOTdL3rFQ/lRdBnntKVOX6k5cKJwEc1HdilT71BWEu7J41gXIB2MRp+vxduPSwZJPWBxEzv4yH1wYLJGUHX4Q=="],
-
-    "@electron/universal/fs-extra/jsonfile": ["jsonfile@6.2.1", "", { "dependencies": { "universalify": "^2.0.0" }, "optionalDependencies": { "graceful-fs": "^4.1.6" } }, "sha512-zwOTdL3rFQ/lRdBnntKVOX6k5cKJwEc1HdilT71BWEu7J41gXIB2MRp+vxduPSwZJPWBxEzv4yH1wYLJGUHX4Q=="],
-
    "@electron/universal/minimatch/brace-expansion": ["brace-expansion@2.1.4", "", { "dependencies": { "balanced-match": "^1.0.0" } }, "sha512-hGfVzPxthbf3+2yjg/RBs60cB0FhqBS/zvdV/4wn4/BmN0bNMMHPc4V/BbFieqf1TKAGGAHnY4eSjajCl0f2Xg=="],

-    "@electron/windows-sign/fs-extra/jsonfile": ["jsonfile@6.2.1", "", { "dependencies": { "universalify": "^2.0.0" }, "optionalDependencies": { "graceful-fs": "^4.1.6" } }, "sha512-zwOTdL3rFQ/lRdBnntKVOX6k5cKJwEc1HdilT71BWEu7J41gXIB2MRp+vxduPSwZJPWBxEzv4yH1wYLJGUHX4Q=="],
-
    "@expressive-code/plugin-shiki/shiki/@shikijs/core": ["@shikijs/core@3.23.0", "", { "dependencies": { "@shikijs/types": "3.23.0", "@shikijs/vscode-textmate": "^10.0.2", "@types/hast": "^3.0.4", "hast-util-to-html": "^9.0.5" } }, "sha512-NSWQz0riNb67xthdm5br6lAkvpDJRTgB36fxlo37ZzM2yq0PQFFzbd8psqC2XMPgCzo1fW6cVi18+ArJ44wqgA=="],

    "@expressive-code/plugin-shiki/shiki/@shikijs/engine-javascript": ["@shikijs/engine-javascript@3.23.0", "", { "dependencies": { "@shikijs/types": "3.23.0", "@shikijs/vscode-textmate": "^10.0.2", "oniguruma-to-es": "^4.3.4" } }, "sha512-aHt9eiGFobmWR5uqJUViySI1bHMqrAgamWE1TYSUoftkAeCCAiGawPMwM+VCadylQtF4V3VNOZ5LmfItH5f3yA=="],
@@ -7013,8 +6976,6 @@

    "@jsx-email/doiuse-email/htmlparser2/entities": ["entities@4.5.0", "", {}, "sha512-V0hjH4dGPh9Ao5p0MoRY6BVqtwCjhz6vI5LT8AJ55H+4g9/4vbHx1I54fS0XuclLhDHArPQCiMjDxjaL8fPxhw=="],

-    "@malept/flatpak-bundler/fs-extra/jsonfile": ["jsonfile@6.2.1", "", { "dependencies": { "universalify": "^2.0.0" }, "optionalDependencies": { "graceful-fs": "^4.1.6" } }, "sha512-zwOTdL3rFQ/lRdBnntKVOX6k5cKJwEc1HdilT71BWEu7J41gXIB2MRp+vxduPSwZJPWBxEzv4yH1wYLJGUHX4Q=="],
-
    "@octokit/auth-app/@octokit/request/@octokit/endpoint": ["@octokit/endpoint@11.0.4", "", { "dependencies": { "@octokit/types": "^17.0.0", "universal-user-agent": "^7.0.2" } }, "sha512-f1cOWoHPmxryJFknxbtDdjODWfV8A9tc8Aae6ermXPNgHFZ/x91AtHIz4gicEjL8hkJiip+u21QHJORfBv/qiA=="],

    "@octokit/auth-app/@octokit/request/@octokit/types": ["@octokit/types@17.0.0", "", { "dependencies": { "@octokit/openapi-types": "^28.0.0" } }, "sha512-ByP1v7YL5SMveFPP7+sj0/ZuWCOOg/Chs4NafOMpq6WNIM/hdGY0S7C0TCGDBWu1aGmOxmUIhMx3cO+IdwYZ1Q=="],
@@ -7393,8 +7354,6 @@

    "cliui/strip-ansi/ansi-regex": ["ansi-regex@5.0.1", "", {}, "sha512-quJQXlTSUGL2LH9SUXo8VwsY4soanhgo6LNSm84E1LBcE8s3O0wpdiRzyR9z/ZZJMlMWv37qOOb9pdJlMUEKFQ=="],

-    "conf/dot-prop/type-fest": ["type-fest@5.8.0", "", { "dependencies": { "tagged-tag": "^1.0.0" } }, "sha512-YGYEVz3Fm5iy/AybuA0oyNFq7H4CgQNfRp/qfe8nurE1kuCeNm3/vfm9X4Mtl+qLyaKJUh5xrFZwogr41SMjYA=="],
-
    "cross-spawn/which/isexe": ["isexe@2.0.0", "", {}, "sha512-RHxMLp9lnKHGHRng9QFhRCMbYAcVpn69smSGcq3f36xjgVVWThj4qqLbTLlq7Ssj8B+fIQ1EuCEGI2lKsyQeIw=="],

    "csso/css-tree/mdn-data": ["mdn-data@2.0.28", "", {}, "sha512-aylIc7Z9y4yzHYAJNuESG3hfhC+0Ibp/MAMiaOZgNv4pmEdFyfZhhhny4MNiAfWdBQ1RQ2mfDWmM1x8SvGyp8g=="],
@@ -7419,6 +7378,8 @@

    "electron-updater/js-yaml/argparse": ["argparse@2.0.1", "", {}, "sha512-8+9WqebbFzpX9OR+Wa6O29asIogeRMzcGtAINdpMHHyAg10f05aSFVBbcEqGf/PXw1EjAZ+q2/bEBg3DvurK3Q=="],

+    "electron-winstaller/fs-extra/jsonfile": ["jsonfile@4.0.0", "", { "optionalDependencies": { "graceful-fs": "^4.1.6" } }, "sha512-m6F1R3z8jjlf2imQHS2Qez5sjKWQzbuuhuJ/FKYFRZvPE3PuHcSMVZzfsLhGVOkfd20obL5SWEBew5ShlquNxg=="],
+
    "electron-winstaller/fs-extra/universalify": ["universalify@0.1.2", "", {}, "sha512-rBJeI5CXAlmy1pV+617WB9J63U6XcazHHF2f2dbJix4XzpUF0RS3Zbj0FGIOCAva5P/d/GBOYaACQ1w+0azUkg=="],

    "electron/@electron/get/env-paths": ["env-paths@3.0.0", "", {}, "sha512-dtJUTepzMW3Lm/NPxRf3wP4642UWhjL2sQxc+ym2YMj1m/H2zDNQOlezafzkHwn6sMstjHTwG6iQQsctDW/b1A=="],
@@ -7567,8 +7528,6 @@

    "tw-to-css/tailwindcss/postcss": ["postcss@8.5.26", "", { "dependencies": { "nanoid": "^3.3.17", "picocolors": "^1.1.1", "source-map-js": "^1.2.1" } }, "sha512-u82N74LFzG8ca+dD8puPnplTXoGH4fTPpVGuIbt36G3qvNlkvfD0lEAZSxaly3KX8TS/L1A1gsCEmvKmBcVbkQ=="],

-    "unzipper/fs-extra/jsonfile": ["jsonfile@6.2.1", "", { "dependencies": { "universalify": "^2.0.0" }, "optionalDependencies": { "graceful-fs": "^4.1.6" } }, "sha512-zwOTdL3rFQ/lRdBnntKVOX6k5cKJwEc1HdilT71BWEu7J41gXIB2MRp+vxduPSwZJPWBxEzv4yH1wYLJGUHX4Q=="],
-
    "venice-ai-sdk-provider/@ai-sdk/openai-compatible/@ai-sdk/provider": ["@ai-sdk/provider@3.0.15", "", { "dependencies": { "json-schema": "^0.4.0" } }, "sha512-XeZW1CcDF2GMbH4wejW6xBRI2QCOgnkVYUnxoeDadB1mf85riL2bMUeDoh+6gJ/r4mjNfzUPW8OjLjvwTP0u1Q=="],

    "venice-ai-sdk-provider/@ai-sdk/openai-compatible/@ai-sdk/provider-utils": ["@ai-sdk/provider-utils@4.0.46", "", { "dependencies": { "@ai-sdk/provider": "3.0.15", "@standard-schema/spec": "^1.1.0", "eventsource-parser": "^3.0.8", "undici": "^6.28.0" }, "peerDependencies": { "zod": "^3.25.76 || ^4.1.8" } }, "sha512-tEtld97plCFiYevsJuOkGkeuhQndeMWFBVrJS4AjnbD5AqrNSXRCe0p+BZ3Cju/sxDeeZ9ym3q9YUV8fASA7aQ=="],
@@ -7577,8 +7536,6 @@

    "vscode-languageserver/vscode-languageserver-protocol/vscode-jsonrpc": ["vscode-jsonrpc@8.2.0", "", {}, "sha512-C+r0eKJUIfiDIfwJhria30+TYWPtuHJXHtI7J0YlOmKAo7ogxP20T0zxB7HZQIFhIyvoBPwWskjxrvAtfjyZfA=="],

-    "workbox-build/fs-extra/jsonfile": ["jsonfile@6.2.1", "", { "dependencies": { "universalify": "^2.0.0" }, "optionalDependencies": { "graceful-fs": "^4.1.6" } }, "sha512-zwOTdL3rFQ/lRdBnntKVOX6k5cKJwEc1HdilT71BWEu7J41gXIB2MRp+vxduPSwZJPWBxEzv4yH1wYLJGUHX4Q=="],
-
    "wrangler/esbuild/@esbuild/aix-ppc64": ["@esbuild/aix-ppc64@0.25.4", "", { "os": "aix", "cpu": "ppc64" }, "sha512-1VCICWypeQKhVbE9oW/sJaAmjLxhVqacdkvPLEjwlttjfwENRSClS8EjBz0KzRyFSCPDIkuXW34Je/vk7zdB7Q=="],

    "wrangler/esbuild/@esbuild/android-arm": ["@esbuild/android-arm@0.25.4", "", { "os": "android", "cpu": "arm" }, "sha512-QNdQEps7DfFwE3hXiU4BZeOV68HHzYwGd0Nthhd3uCkkEKK7/R6MTgM0P7H7FAs5pU/DIWsviMmEGxEoxIZ+ZQ=="],
@@ -1,8 +1,8 @@
 {
  "nodeModules": {
-    "x86_64-linux": "sha256-TlCPtuIvTNF01fLI0yHCLzVkx53yF9xxvAObDMGeo8M=",
-    "aarch64-linux": "sha256-aEjyPIXHeA5w1iZXbPKJAOIJQBfXg+LAx/y7C5uFz4g=",
-    "aarch64-darwin": "sha256-lthMTio2qNy+H2tL9cAPmqC41O+wdSADI61cnW4dIb0=",
-    "x86_64-darwin": "sha256-ONFbRQnwzOYHo0Pyh327QfJG2uzqzNEn/SS2vbYYMdM="
+    "x86_64-linux": "sha256-8mOzCscBAuogG4tm8CroqjTX5E5yzCvTobbhKvxQP0U=",
+    "aarch64-linux": "sha256-drrRSpzxC8bfaTXBpOyaN0QAyBVV7WJzm0NstJ+8sAE=",
+    "aarch64-darwin": "sha256-YY5A/zxLPONvgnI+DZlzcD2K5Q9PIw4F2YbDxKbT4UU=",
+    "x86_64-darwin": "sha256-/c/Ew4onA+9+l6GRKXz3zWq3QFESM7j5RyGLCWRPQFw="
  }
 }
@@ -2,7 +2,7 @@
  "$schema": "https://json.schemastore.org/package.json",
  "name": "opencode",
  "description": "AI-powered development tool",
-  "version": "2.0.8",
+  "version": "2.0.11",
  "private": true,
  "type": "module",
  "packageManager": "bun@1.4.2",
@@ -12,7 +12,7 @@

 Per-type constructors live on the type, not as top-level re-exports. Use `Message.system(...)`, `Message.user(...)`, `Message.assistant(...)`, `Message.tool(...)`, `LanguageModel.make(...)`, `ToolDefinition.make(...)`, `ToolCallPart.make(...)`, `ToolResultPart.make(...)`, `ToolChoice.make(...)`, `ToolChoice.named(...)`, `SystemPart.make(...)`, and `GenerationOptions.make(...)` directly. The top-level `LLM` namespace is reserved for request-shaped call APIs: `LLM.request`, `LLM.generate`, `LLM.stream`, and `LLM.generateObject`. Use `LLMRequest.update(...)` when deriving canonical request data; do not add a duplicate `LLM.updateRequest(...)` path. Two ways to construct the same thing is one too many.

- Keep provider-defined string enums forward-compatible. Expose known values for autocomplete while accepting future values with `Known | (string & {})`; use `Schema.String` at runtime unless rejecting unknown values is required for correctness.
+- Prefer forward compatibility for provider-defined options that OpenCode only passes through. For pass-through string enums, expose known values for autocomplete while accepting future values with `Known | (string & {})`, and accept any string at runtime. Closed literals are appropriate when OpenCode branches on a value, transforms its associated structure, or otherwise cannot correctly handle an unknown variant. New options whose shape or behavior requires implementation remain unsupported until they are handled; do not blindly forward unknown structures.
 - Order reasoning-effort values from lowest to highest: `none`, `minimal`, `low`, `medium`, `high`, `xhigh`, `max`. Provider-specific subsets follow the same relative order in types, schemas, option lists, and tests.

 ## Tests
@@ -1,6 +1,6 @@
 {
  "$schema": "https://json.schemastore.org/package.json",
-  "version": "2.0.8",
+  "version": "2.0.11",
  "name": "@opencode/ai",
  "type": "module",
  "license": "MIT",
@@ -83,7 +83,7 @@ const AnthropicCacheControl = Schema.Struct({
  type: Schema.tag("ephemeral"),
  ttl: Schema.optional(Schema.Literals(["5m", "1h"])),
 })
-const AnthropicServiceTier = Schema.Literals(["auto", "standard_only"])
+const AnthropicServiceTier = knownString<"auto" | "standard_only">()

 const AnthropicTextBlock = Schema.Struct({
  type: Schema.tag("text"),
@@ -276,7 +276,7 @@ const AnthropicThinkingBlockBinding = Schema.Struct({
 })

 const AnthropicThinkingFields = {
-  display: Schema.optional(Schema.Literals(["summarized", "omitted"])),
+  display: Schema.optional(knownString<"summarized" | "omitted">()),
  block_binding: Schema.optional(AnthropicThinkingBlockBinding),
 }
 const AnthropicThinkingEnabled = Schema.Struct({
@@ -73,11 +73,6 @@ const driver = (options: Options, body: string): WebSocketChannelDriver => {
          )
        if (event.type === "error") {
          terminal = true
-          yield* OpenResponses.decodeKnownErrorEvent(event).pipe(
-            Effect.mapError((cause) =>
-              ProviderShared.eventError(options.id, `${options.name} returned a malformed error event`, frame, cause),
-            ),
-          )
          return {
            type: "provider-failure",
            error: OpenResponses.providerFailure(event, `${options.name} stream error`, frame),
@@ -108,7 +108,7 @@ const incremental = (
  return input.slice(baseline.length)
 }

-const code = (event: OpenResponses.Event) => event.code || event.error?.code || event.response?.error?.code || undefined
+const code = (event: OpenResponses.Event) => OpenResponses.errorDetail(event).code

 const rejected = (
  observation: Extract<ChannelObservation, { readonly type: "provider-failure" }>,
@@ -1,4 +1,4 @@
-import { Effect, Option, Schema, SchemaGetter } from "effect"
+import { Effect, Option, Schema } from "effect"
 import type { Content } from "@opencode/schema/tool"
 import { HttpTransport } from "../route/transport/index.js"
 import { Protocol } from "../route/protocol.js"
@@ -333,53 +333,13 @@ export const StreamItem = Schema.StructWithRest(
 export type StreamItem = Schema.Schema.Type<typeof StreamItem>
 export type OutputItem = StreamItem & { readonly id: string }

-// Responses-compatible providers put streaming error details at the top level or
-// under `error`, and response failures under `response.error`. Accept all three shapes.
+// Responses-compatible providers put error details at the top level, under `error`, or under
+// `response.error`, and gateways reshape them freely: strings, numeric codes, extra fields. Those
+// fields decode as opaque values and `errorDetail` reads them defensively, so an error frame can
+// only fail on invalid JSON and otherwise always classifies with the raw body as the fallback.
 // https://www.openresponses.org/specification
-const OpenResponsesErrorObject = Schema.Struct({
-  type: optionalNull(Schema.String),
-  code: optionalNull(Schema.String),
-  message: optionalNull(Schema.String),
-  param: optionalNull(Schema.String),
-})
-const OpenResponsesErrorPayload = Schema.Union([Schema.String, OpenResponsesErrorObject]).pipe(
-  Schema.decodeTo(OpenResponsesErrorObject, {
-    decode: SchemaGetter.transform((error) => (typeof error === "string" ? { message: error } : error)),
-    encode: SchemaGetter.passthrough(),
-  }),
-)
-type OpenResponsesErrorPayload = Schema.Schema.Type<typeof OpenResponsesErrorPayload>
-
-const WebSocketErrorHeader = Schema.Union([Schema.String, Schema.Number, Schema.Boolean])
-export const WebSocketErrorEvent = Schema.StructWithRest(
-  Schema.Struct({
-    type: Schema.tag("error"),
-    status: Schema.optional(Schema.Number),
-    status_code: Schema.optional(Schema.Number),
-    code: optionalNull(Schema.String),
-    message: Schema.optional(Schema.String),
-    param: optionalNull(Schema.String),
-    error: optionalNull(OpenResponsesErrorPayload),
-    headers: Schema.optional(Schema.Record(Schema.String, WebSocketErrorHeader)),
-  }),
-  [Schema.Record(Schema.String, Schema.Unknown)],
-)
-const decodeWebSocketErrorEvent = Schema.decodeUnknownEffect(WebSocketErrorEvent)
-
-export const decodeKnownErrorEvent = (event: Event) =>
-  decodeWebSocketErrorEvent({
-    ...event,
-    status: typeof event.status === "number" ? event.status : undefined,
-    status_code: typeof event.status_code === "number" ? event.status_code : undefined,
-    headers: ProviderShared.isRecord(event.headers)
-      ? Object.fromEntries(
-          Object.entries(event.headers).filter(
-            (entry): entry is [string, string | number | boolean] =>
-              typeof entry[1] === "string" || typeof entry[1] === "number" || typeof entry[1] === "boolean",
-          ),
-        )
-      : undefined,
-  })
+const asText = (value: unknown) =>
+  typeof value === "string" && value.length > 0 ? value : typeof value === "number" ? String(value) : undefined

 export const Event = Schema.StructWithRest(
  Schema.Struct({
@@ -400,31 +360,18 @@ export const Event = Schema.StructWithRest(
          incomplete_details: optionalNull(Schema.Struct({ reason: Schema.optional(Schema.String) })),
          output: Schema.optional(Schema.Array(StreamItem)),
          usage: optionalNull(OpenResponsesUsage),
-          error: optionalNull(OpenResponsesErrorPayload),
+          error: Schema.optional(Schema.Unknown),
        }),
        [Schema.Record(Schema.String, Schema.Unknown)],
      ),
    ),
-    code: optionalNull(Schema.String),
-    message: Schema.optional(Schema.String),
-    param: optionalNull(Schema.String),
-    error: optionalNull(OpenResponsesErrorPayload),
+    code: Schema.optional(Schema.Unknown),
+    message: Schema.optional(Schema.Unknown),
+    error: Schema.optional(Schema.Unknown),
    status: Schema.optional(Schema.Unknown),
    status_code: Schema.optional(Schema.Unknown),
-    headers: Schema.optional(Schema.Unknown),
  }),
  [Schema.Record(Schema.String, Schema.Unknown)],
-).pipe(
-  Schema.decode({
-    decode: SchemaGetter.transform((event) => {
-      if (event.type !== "error" || event.error != null) return event
-      const { code, message, param, ...rest } = event
-      if (code === undefined && message === undefined && param === undefined) return event
-      // Flat errors (for example, Meta's) can also arrive through generic Responses endpoints.
-      return { ...rest, error: { code, message, param } }
-    }),
-    encode: SchemaGetter.passthrough(),
-  }),
 )
 export type Event = Schema.Schema.Type<typeof Event>
 export type NormalizedEvent = Event & { readonly item?: OutputItem | null }
@@ -433,16 +380,15 @@ const decodeEventValue = Schema.decodeUnknownEffect(Event)
 const decodeFrame = Schema.decodeUnknownEffect(ProviderShared.Json)

 /**
- * Decodes one WebSocket frame. xAI answers a rejected `response.create` with `{ "error": { "message", "type" } }` and no
- * event type; that envelope reads as an error event so the failure classifies instead of failing decoding.
+ * Decodes one WebSocket frame. Some providers and gateways answer a rejected `response.create` with a bare
+ * `{ "error": ... }` envelope and no event type; that reads as an error event so it classifies instead of
+ * failing decoding.
 */
 export const decodeChannelEvent = (frame: string) =>
  decodeFrame(frame).pipe(
    Effect.flatMap((value) =>
      decodeEventValue(
-        ProviderShared.isRecord(value) &&
-          value.type === undefined &&
-          (typeof value.error === "string" || ProviderShared.isRecord(value.error))
+        ProviderShared.isRecord(value) && value.type === undefined && value.error != null
          ? { ...value, type: "error" }
          : value,
      ),
@@ -1422,22 +1368,21 @@ const onResponseFinish = Effect.fn("OpenResponses.onResponseFinish")(function* (
  return [{ ...current, lifecycle }, events] satisfies StepResult
 })

-// Build the prettiest summary available from whatever the provider supplied.
-// When both code and message are present, prefix the code so consumers see
-// the failure mode (e.g. `rate_limit_exceeded: Slow down`) instead of just
-// the bare message — production rate limits and context-length failures used
-// to be indistinguishable from generic stream drops. Returns undefined when
-// the payload carries no usable summary.
-const providerErrorMessage = (event: Event, nested: OpenResponsesErrorPayload | undefined): string | undefined => {
-  const message = event.message || nested?.message || undefined
-  const code = event.code || nested?.code || undefined
-  if (message && code) return `${code}: ${message}`
-  return message || code
+/** Error code and message from wherever the frame put them; top-level fields win over nested ones. */
+export const errorDetail = (event: Event) => {
+  const raw = event.error ?? event.response?.error
+  const nested = typeof raw === "string" ? { message: raw } : ProviderShared.isRecord(raw) ? raw : undefined
+  return {
+    message: asText(event.message) ?? asText(nested?.message),
+    code: asText(event.code) ?? asText(nested?.code),
+  }
 }

+// Prefix the code when both are present (`rate_limit_exceeded: Slow down`) so the failure mode is
+// visible; fall back to the raw frame rather than a generic message when neither decodes.
 export const providerFailure = (event: Event, fallback: string, body = ProviderShared.encodeJson(event)) => {
-  const nested = event.error ?? event.response?.error ?? undefined
-  const summary = providerErrorMessage(event, nested)
+  const detail = errorDetail(event)
+  const summary = detail.message && detail.code ? `${detail.code}: ${detail.message}` : (detail.message ?? detail.code)
  const message = summary ?? (body === "{}" ? fallback : body)
  const status =
    typeof event.status === "number"
@@ -1520,18 +1465,7 @@ export const step = (state: ParserState, event: NormalizedEvent) => {
  if (event.type === "response.output_item.done") return onOutputItemDone(state, event.item)
  if (event.type === "response.completed" || event.type === "response.incomplete") return onResponseFinish(state, event)
  if (event.type === "response.failed") return providerFailure(event, `${state.name} response failed`)
-  if (event.type === "error")
-    return decodeKnownErrorEvent(event).pipe(
-      Effect.mapError((cause) =>
-        ProviderShared.eventError(
-          state.id,
-          `${state.name} returned a malformed error event`,
-          ProviderShared.encodeJson(event),
-          cause,
-        ),
-      ),
-      Effect.flatMap(() => providerFailure(event, `${state.name} stream error`)),
-    )
+  if (event.type === "error") return providerFailure(event, `${state.name} stream error`)
  return Effect.succeed<StepResult>([state, NO_EVENTS])
 }

@@ -215,7 +215,9 @@ export const fromWebSocket = (
 ): Effect.Effect<WebSocketConnection, AIError> =>
  Effect.gen(function* () {
    yield* waitOpen(ws, input)
-    const messages = yield* Queue.bounded<string | Uint8Array, AIError | Cause.Done<void>>(128)
+    // The socket pushes frames synchronously and cannot be paused, so the hand-off to the consumer
+    // fiber must absorb whole read buffers. Bun delivers over a thousand small frames in one tick.
+    const messages = yield* Queue.unbounded<string | Uint8Array, AIError | Cause.Done<void>>()

    const oversized = (message: string | Uint8Array) =>
      typeof message === "string" ? new Blob([message]).size > MAX_FRAME_BYTES : message.byteLength > MAX_FRAME_BYTES
@@ -238,19 +240,7 @@ export const fromWebSocket = (
    }
    const offer = (message: string | Uint8Array) => {
      if (rejectOversized(message)) return
-      if (Queue.offerUnsafe(messages, message)) return
-      Queue.failCauseUnsafe(
-        messages,
-        Cause.fail(
-          transportError("WebSocket inbound queue overflow", {
-            body: typeof message === "string" ? message : new TextDecoder().decode(message),
-            url: input.url,
-            operation: "read",
-            code: "queue-overflow",
-            phase: "receive",
-          }),
-        ),
-      )
+      Queue.offerUnsafe(messages, message)
    }

    const onMessage = (event: MessageEvent) => {
@@ -4,6 +4,22 @@ import { Anthropic } from "../../src/providers.js"
 const model = Anthropic.provider.model("claude-sonnet-4-5")

 LLM.request({ model, prompt: "Hello", providerOptions: { thinking: { type: "adaptive" } } })
+LLM.request({
+  model,
+  prompt: "Hello",
+  providerOptions: {
+    serviceTier: "future-tier",
+    thinking: { type: "adaptive", display: "future-display" },
+  },
+})
+LLM.request({
+  model,
+  prompt: "Hello",
+  providerOptions: {
+    // @ts-expect-error Anthropic cache TTL values are protocol constraints.
+    cacheControl: { type: "ephemeral", ttl: "future-ttl" },
+  },
+})

 LLM.request({
  model,
@@ -215,13 +215,31 @@ describe("Anthropic Messages route", () => {
    }),
  )

+  it.effect("forwards unknown values for pass-through string enums", () =>
+    Effect.gen(function* () {
+      const prepared = yield* compileRequest(
+        LLMRequest.update(request, {
+          providerOptions: {
+            service_tier: "future-tier",
+            thinking: { type: "adaptive", display: "future-display" },
+          },
+        }),
+      )
+
+      expect(prepared.body).toMatchObject({
+        service_tier: "future-tier",
+        thinking: { type: "adaptive", display: "future-display" },
+      })
+    }),
+  )
+
  it.effect("ignores unknown provider options and rejects malformed known ones", () =>
    Effect.gen(function* () {
      const prepared = yield* compileRequest(LLMRequest.update(request, { providerOptions: { unknownOption: true } }))
      const malformed = [
-        { service_tier: "fast" },
+        { service_tier: 1 },
        { metadata: { user_id: 42 } },
-        { cache_control: { type: "ephemeral", ttl: "2h" } },
+        { cache_control: { type: "ephemeral", ttl: "future-ttl" } },
        { output_config: { format: { type: "text" } } },
        { thinking: { type: "automatic" } },
      ]
@@ -11,66 +11,78 @@ import { sseEvents } from "../lib/sse.js"

 const decodeEvent = Schema.decodeUnknownEffect(OpenResponses.protocol.stream.event)

-it.effect("normalizes flat errors in shared SSE and WebSocket decoding", () =>
+it.effect("decodes error frames verbatim in shared SSE and WebSocket decoding", () =>
  Effect.gen(function* () {
-    const frame = {
-      type: "error",
-      sequence_number: 4,
-      code: "server_shutting_down",
-      message: "Server is shutting down. Please retry your request.",
-      param: null,
-    }
    for (const decode of [decodeEvent, OpenResponses.decodeChannelEvent]) {
-      const event = yield* decode(JSON.stringify(frame))
-      expect(event).toEqual({
-        type: "error",
-        sequence_number: 4,
-        error: { code: frame.code, message: frame.message, param: null },
-      })
-
-      for (const unchanged of [
-        event,
+      for (const frame of [
+        { type: "error", sequence_number: 4, code: "server_shutting_down", message: "Shutting down", param: null },
        { type: "error" },
+        { type: "error", error: "Gateway failed" },
+        { type: "error", error: { code: 429, message: "slow down" } },
+        { type: "error", error: 42 },
+        { type: "error", code: 500, message: ["not", "a", "string"] },
+        { type: "response.failed", response: { id: "resp_failed", error: "Gateway failed" } },
+        { type: "response.failed", response: { id: "resp_failed", error: ["weird"] } },
        {
          type: "response.failed",
          response: { id: "resp_failed", error: { code: "server_error", message: "Internal server error" } },
        },
        { type: "response.output_text.delta", item_id: "msg_text", delta: "Hello" },
      ]) {
-        expect(yield* decode(JSON.stringify(unchanged))).toEqual(unchanged)
+        expect(yield* decode(JSON.stringify(frame))).toEqual(frame)
      }
    }
  }),
 )

-it.effect("continues to normalize untyped xAI WebSocket errors", () =>
+it.effect("reads bare WebSocket error envelopes as error events", () =>
  Effect.gen(function* () {
    const message = "gRPC error: Response with id=resp_missing not found"
-    for (const error of [{ type: "api_error", message }, message]) {
-      expect(yield* OpenResponses.decodeChannelEvent(JSON.stringify({ error }))).toEqual({
-        type: "error",
-        error: typeof error === "string" ? { message } : error,
-      })
+    for (const error of [{ type: "api_error", message }, message, 42]) {
+      expect(yield* OpenResponses.decodeChannelEvent(JSON.stringify({ error }))).toEqual({ type: "error", error })
+    }
+    for (const frame of [{ error: null }, { message }]) {
+      expect(yield* OpenResponses.decodeChannelEvent(JSON.stringify(frame)).pipe(Effect.flip)).toBeDefined()
    }
  }),
 )

-it.effect("normalizes string errors in shared SSE and WebSocket decoding", () =>
+it.effect("extracts error details from every shape and falls back to the raw frame", () =>
  Effect.gen(function* () {
-    for (const decode of [decodeEvent, OpenResponses.decodeChannelEvent]) {
-      expect(yield* decode(JSON.stringify({ type: "error", error: "Gateway failed" }))).toEqual({
-        type: "error",
-        error: { message: "Gateway failed" },
-      })
-      expect(
-        yield* decode(
-          JSON.stringify({ type: "response.failed", response: { id: "resp_failed", error: "Gateway failed" } }),
-        ),
-      ).toEqual({
-        type: "response.failed",
-        response: { id: "resp_failed", error: { message: "Gateway failed" } },
-      })
+    const cases: Array<[frame: Record<string, unknown>, message: string, tag: string]> = [
+      [
+        { type: "error", code: "server_shutting_down", message: "Shutting down" },
+        "server_shutting_down: Shutting down",
+        "UnknownProvider",
+      ],
+      [{ type: "error", error: "Gateway failed" }, "Gateway failed", "UnknownProvider"],
+      [{ type: "error", error: { code: 429, message: "slow down" } }, "429: slow down", "UnknownProvider"],
+      [{ type: "error", error: { message: "slow down" }, status: 429 }, "slow down", "RateLimit"],
+      [{ type: "error", code: 500, message: ["not", "a", "string"] }, "500", "UnknownProvider"],
+      [
+        { type: "response.failed", response: { id: "resp_failed", error: "Gateway failed" } },
+        "Gateway failed",
+        "UnknownProvider",
+      ],
+    ]
+    for (const [frame, message, tag] of cases) {
+      const event = yield* OpenResponses.decodeChannelEvent(JSON.stringify(frame))
+      const error = OpenResponses.providerFailure(event, "fallback", JSON.stringify(frame))
+      expect(error.message).toBe(message)
+      expect(error.reason._tag).toBe(tag)
+      expect(error.reason.body).toBe(JSON.stringify(frame))
    }
+    for (const frame of [
+      { type: "error", error: 42 },
+      { type: "response.failed", response: { id: "resp_failed", error: ["weird"] } },
+    ]) {
+      const event = yield* OpenResponses.decodeChannelEvent(JSON.stringify(frame))
+      const error = OpenResponses.providerFailure(event, "fallback", JSON.stringify(frame))
+      expect(error.message).toBe(JSON.stringify(frame))
+      expect(error.reason._tag).toBe("UnknownProvider")
+    }
+    expect(OpenResponses.providerFailure({ type: "error" }, "fallback", "{}").message).toBe("fallback")
+    expect(OpenResponses.providerFailure({ type: "error" }, "fallback", "{}").reason._tag).toBe("ProviderInternal")
  }),
 )

@@ -19,6 +19,13 @@ export function mountBrowserPane() {
      session: "Alpha",
      mounted: true,
      visible: true,
+      url: undefined as string | undefined,
+      loading: false,
+      generation: 0,
+      delayNavigation: false,
+      pendingURL: undefined as string | undefined,
+      loadErrors: {} as Record<string, string | undefined>,
+      error: undefined as string | undefined,
      layouts: {} as Record<string, BrowserPaneLayout | undefined>,
    })
    const tabs = ["Alpha", "Beta"].map((name) => ({
@@ -47,13 +54,33 @@ export function mountBrowserPane() {
      opened: () => !!registrations.get(store.session),
      state: () => ({ tabs: tabs.filter((tab) => tab.title === store.session), focusedTabID: null }),
      tabs: () => tabs.filter((tab) => tab.title === store.session),
-      active: () => tabs.find((tab) => tab.title === store.session) ?? tabs[0],
+      active: () => {
+        const tab = tabs.find((tab) => tab.title === store.session) ?? tabs[0]
+        return {
+          ...tab,
+          url: store.url ?? tab.url,
+          loading: store.loading,
+          generation: store.generation,
+          loadError: store.loadErrors[store.session],
+        }
+      },
      registration: () => registrations.get(store.session),
-      error: () => undefined,
+      error: () => store.error ?? (store.loadErrors[store.session] ? "Request failed" : undefined),
      suspended: () => false,
      close: () => undefined,
      open: () => undefined,
-      command: () => undefined,
+      command: (command) => {
+        setStore("error", undefined)
+        if (command.type === "navigate" || command.type === "reload") setStore("loadErrors", store.session, undefined)
+        if (command.type === "navigate") {
+          if (store.delayNavigation) {
+            setStore("pendingURL", command.url)
+            return
+          }
+          setStore({ url: command.url, loading: false, generation: store.generation + 1 })
+        }
+        if (command.type === "stop") setStore("loading", false)
+      },
    }
    return (
      <>
@@ -64,6 +91,32 @@ export function mountBrowserPane() {
            {(name) => <button onClick={() => setStore({ session: name, mounted: name !== "Empty" })}>{name}</button>}
          </For>
          <button onClick={() => setStore("mounted", false)}>Unmount pane</button>
+          <button onClick={() => setStore({ url: "about:blank", loading: false })}>Blank page</button>
+          <button onClick={() => setStore({ url: "about:blank", loading: true })}>Loading page</button>
+          <button
+            onClick={() =>
+              setStore({ loading: true, generation: store.generation + 1, loadErrors: { [store.session]: undefined } })
+            }
+          >
+            Load current page
+          </button>
+          <button onClick={() => setStore("loadErrors", store.session, "ERR_CONNECTION_REFUSED")}>Failed page</button>
+          <button onClick={() => setStore("delayNavigation", true)}>Delay navigation</button>
+          <button onClick={() => setStore({ error: "ERR_BLOCKED_BY_CLIENT", pendingURL: undefined })}>
+            Block navigation
+          </button>
+          <button
+            onClick={() =>
+              setStore({
+                url: store.pendingURL,
+                pendingURL: undefined,
+                loading: false,
+                generation: store.generation + 1,
+              })
+            }
+          >
+            Complete navigation
+          </button>
          <button onClick={() => setStore("visible", (visible) => !visible)}>Toggle Review tab</button>
        </nav>
        <div style={{ width: "640px", height: "360px", border: "1px solid #555" }}>
@@ -57,3 +57,153 @@ story("hides the native view immediately while the pane stays mounted", async ({
  await toggle.click()
  await expect(root.getByTestId("native-Alpha")).toHaveAttribute("data-visible", "true")
 })
+
+story("shows the empty state over a blank native page and restores navigation", async ({ page }) => {
+  const root = page.getByTestId("browser-pane-fixture")
+  await root.getByRole("button", { name: "Blank page", exact: true }).click()
+  await expect(root.getByText("Enter URL", { exact: true })).toBeVisible()
+  await expect(root.getByText('Or prompt "Open in the app browser"', { exact: true })).toBeVisible()
+  await expect(root.getByTestId("native-Alpha")).toHaveAttribute("data-visible", "false")
+  await expect(root.getByRole("button", { name: "Reload", exact: true })).toBeDisabled()
+
+  const address = root.getByRole("textbox", { name: "Browser address", exact: true })
+  await address.fill("https://example.com/")
+  await expect(root.getByText("Enter URL", { exact: true })).toBeVisible()
+  await address.press("Enter")
+  await expect(address).not.toBeFocused()
+  await expect(root.getByText("Enter URL", { exact: true })).toBeHidden()
+  await expect(root.getByTestId("native-Alpha")).toHaveAttribute("data-visible", "true")
+  await expect(root.getByRole("button", { name: "Reload", exact: true })).toBeEnabled()
+})
+
+story("keeps Stop available and hides the empty state while a blank page loads", async ({ page }) => {
+  const root = page.getByTestId("browser-pane-fixture")
+  await root.getByRole("button", { name: "Loading page", exact: true }).click()
+  await expect(root.getByText("Enter URL", { exact: true })).toBeHidden()
+  await root.getByRole("button", { name: "Stop", exact: true }).click()
+  await expect(root.getByText("Enter URL", { exact: true })).toBeVisible()
+  await expect(root.getByTestId("native-Alpha")).toHaveAttribute("data-visible", "false")
+})
+
+story("keeps the submitted URL visible until the browser reports navigation", async ({ page }) => {
+  const root = page.getByTestId("browser-pane-fixture")
+  await root.getByRole("button", { name: "Blank page", exact: true }).click()
+  await root.getByRole("button", { name: "Delay navigation", exact: true }).click()
+  const address = root.getByRole("textbox", { name: "Browser address", exact: true })
+  await address.fill("https://example.com/")
+  await address.press("Enter")
+  await expect(address).not.toBeFocused()
+  await expect(address).toHaveValue("https://example.com/")
+  await expect(root.getByText("Enter URL", { exact: true })).toBeHidden()
+
+  await root.getByRole("button", { name: "Complete navigation", exact: true }).click()
+  await expect(root.getByTestId("native-Alpha")).toHaveAttribute("data-visible", "true")
+  await expect(address).toHaveValue("https://example.com/")
+
+  await address.fill("https://unsubmitted.example/")
+  await root.getByRole("button", { name: "Delay navigation", exact: true }).click()
+  await expect(address).toHaveValue("https://example.com/")
+})
+
+story("restores the current URL when a submitted navigation is blocked", async ({ page }) => {
+  const root = page.getByTestId("browser-pane-fixture")
+  await root.getByRole("button", { name: "Delay navigation", exact: true }).click()
+  const address = root.getByRole("textbox", { name: "Browser address", exact: true })
+  await address.fill("https://blocked.example/")
+  await address.press("Enter")
+  await expect(address).toHaveValue("https://blocked.example/")
+  await root.getByRole("button", { name: "Block navigation", exact: true }).click()
+  await expect(root.getByText("ERR_BLOCKED_BY_CLIENT", { exact: true })).toBeVisible()
+  await expect(address).toHaveValue("https://alpha.example/")
+  await expect(root.getByTestId("native-Alpha")).toHaveAttribute("data-visible", "true")
+})
+
+story("shows a themed failure state for only the failed tab and allows retry", async ({ page }) => {
+  const root = page.getByTestId("browser-pane-fixture")
+  await root.getByRole("button", { name: "Failed page", exact: true }).click()
+  await expect(root.getByText("URL can't be reached", { exact: true })).toBeVisible()
+  await expect(root.getByText("Check the URL and your connection, then try again.", { exact: true })).toBeVisible()
+  await expect(root.getByText("Request failed", { exact: true })).toBeHidden()
+  await expect(root.getByTestId("native-Alpha")).toHaveAttribute("data-visible", "false")
+  await expect(root.getByRole("textbox", { name: "Browser address", exact: true })).toHaveValue(
+    "https://alpha.example/",
+  )
+
+  await root.getByRole("button", { name: "Beta", exact: true }).click()
+  await expect(root.getByText("URL can't be reached", { exact: true })).toBeHidden()
+  await expect(root.getByTestId("native-Beta")).toHaveAttribute("data-visible", "true")
+  await root.getByRole("button", { name: "Alpha", exact: true }).click()
+  await expect(root.getByText("URL can't be reached", { exact: true })).toBeVisible()
+
+  await root.getByRole("button", { name: "Reload", exact: true }).click()
+  await expect(root.getByText("URL can't be reached", { exact: true })).toBeHidden()
+  await expect(root.getByTestId("native-Alpha")).toHaveAttribute("data-visible", "true")
+})
+
+story("returns a failed tab to the empty state when an empty URL is submitted", async ({ page }) => {
+  const root = page.getByTestId("browser-pane-fixture")
+  await root.getByRole("button", { name: "Failed page", exact: true }).click()
+  await expect(root.getByText("URL can't be reached", { exact: true })).toBeVisible()
+  await root.getByRole("button", { name: "Delay navigation", exact: true }).click()
+
+  const address = root.getByRole("textbox", { name: "Browser address", exact: true })
+  await address.fill("")
+  await address.press("Enter")
+  await expect(address).not.toBeFocused()
+  await expect(address).toHaveValue("")
+  await root.getByRole("button", { name: "Load current page", exact: true }).click()
+  await expect(root.getByRole("button", { name: "Stop", exact: true })).toBeEnabled()
+  await root.getByRole("button", { name: "Complete navigation", exact: true }).click()
+  await expect(root.getByText("URL can't be reached", { exact: true })).toBeHidden()
+  await expect(root.getByText("Enter URL", { exact: true })).toBeVisible()
+  await expect(root.getByRole("button", { name: "Reload", exact: true })).toBeDisabled()
+  await expect(root.getByTestId("native-Alpha")).toHaveAttribute("data-visible", "false")
+})
+
+story("selects the full URL when the address field gains focus", async ({ page }) => {
+  const root = page.getByTestId("browser-pane-fixture")
+  const address = root.getByRole("textbox", { name: "Browser address", exact: true })
+  await address.click()
+  await expect(address).toHaveJSProperty("selectionStart", 0)
+  await expect(address).toHaveJSProperty("selectionEnd", "https://alpha.example/".length)
+  await address.pressSequentially("https://example.com/")
+  await expect(address).toHaveValue("https://example.com/")
+  await address.press("Enter")
+  await expect(address).not.toBeFocused()
+  await address.focus()
+  await expect(address).toHaveJSProperty("selectionStart", 0)
+  await expect(address).toHaveJSProperty("selectionEnd", "https://example.com/".length)
+  await address.press("ArrowRight")
+  await address.click()
+  await expect(address).toHaveJSProperty("selectionStart", 0)
+  await expect(address).toHaveJSProperty("selectionEnd", "https://example.com/".length)
+})
+
+story("keeps the current page visible while a submitted URL loads", async ({ page }) => {
+  const root = page.getByTestId("browser-pane-fixture")
+  await root.getByRole("button", { name: "Delay navigation", exact: true }).click()
+  const address = root.getByRole("textbox", { name: "Browser address", exact: true })
+  await address.fill("https://example.com/")
+  await address.press("Enter")
+  await expect(root.getByTestId("native-Alpha")).toHaveAttribute("data-visible", "true")
+  await expect(address).toHaveValue("https://example.com/")
+
+  await root.getByRole("button", { name: "Load current page", exact: true }).click()
+  await expect(root.getByRole("button", { name: "Stop", exact: true })).toBeEnabled()
+  await expect(root.getByTestId("native-Alpha")).toHaveAttribute("data-visible", "true")
+  await root.getByRole("button", { name: "Complete navigation", exact: true }).click()
+  await expect(root.getByTestId("native-Alpha")).toHaveAttribute("data-visible", "true")
+  await expect(address).toHaveValue("https://example.com/")
+})
+
+story("keeps the current page and restores its URL when an empty address is submitted", async ({ page }) => {
+  const root = page.getByTestId("browser-pane-fixture")
+  const address = root.getByRole("textbox", { name: "Browser address", exact: true })
+  await address.fill("")
+  await address.press("Enter")
+  await expect(address).not.toBeFocused()
+  await expect(address).toHaveValue("https://alpha.example/")
+  await expect(root.getByTestId("native-Alpha")).toHaveAttribute("data-visible", "true")
+  await expect(root.getByText("Enter URL", { exact: true })).toBeHidden()
+  await expect(root.getByRole("button", { name: "Reload", exact: true })).toBeEnabled()
+})
@@ -0,0 +1,110 @@
+import { expect, test, type Locator, type Page } from "@playwright/test"
+import { fixture, pageMessages } from "../smoke/session-timeline.fixture"
+import { mockOpenCodeServer } from "../utils/mock-server"
+
+test.use({ viewport: { width: 390, height: 844 }, hasTouch: true, isMobile: true })
+
+test.beforeEach(async ({ page }) => {
+  await mockOpenCodeServer(page, {
+    sessions: fixture.sessions,
+    provider: fixture.provider,
+    directory: fixture.directory,
+    project: fixture.project,
+    pageMessages,
+  })
+  await page.addInitScript(
+    ({ directory, server, sessions }) => {
+      localStorage.setItem(
+        "opencode.global.dat:server",
+        JSON.stringify({ projects: { local: [{ worktree: directory, expanded: true }] } }),
+      )
+      localStorage.setItem(
+        "opencode.window.browser.dat:tabs",
+        JSON.stringify(sessions.map((session) => ({ type: "session", server, sessionId: session.id }))),
+      )
+    },
+    { directory: fixture.directory, server: fixture.serverKey, sessions: fixture.sessions },
+  )
+  await page.goto("/")
+  await page.locator('[data-slot="mobile-tabs-trigger"]').click()
+  await expect(page.locator('[data-slot="mobile-tabs-drawer"]')).toBeVisible()
+  const drawer = page.locator('[data-slot="mobile-drawer-content"]')
+  await expect
+    .poll(() => drawer.evaluate((element) => new DOMMatrixReadOnly(getComputedStyle(element).transform).m42))
+    .toBe(0)
+  await expect(drawer).not.toHaveAttribute("data-transitioning")
+})
+
+test("reorders session tabs with touch", async ({ page }) => {
+  const tabs = page.locator('[data-slot="vertical-tabs"] a')
+  await expect(tabs).toContainText([fixture.expected.sourceTitle, fixture.expected.targetTitle])
+
+  const target = tabs.filter({ hasText: fixture.expected.targetTitle })
+  const source = tabs.filter({ hasText: fixture.expected.sourceTitle })
+  const targetBox = await target.boundingBox()
+  const sourceBox = await source.boundingBox()
+  expect(targetBox).not.toBeNull()
+  expect(sourceBox).not.toBeNull()
+
+  await touchDrag(page, source, {
+    from: { x: sourceBox!.x + sourceBox!.width / 2, y: sourceBox!.y + sourceBox!.height / 2 },
+    to: { x: targetBox!.x + targetBox!.width / 2, y: targetBox!.y + targetBox!.height / 2 },
+  })
+
+  await expect(tabs).toContainText([fixture.expected.targetTitle, fixture.expected.sourceTitle])
+})
+
+test("dismisses a touch context menu by tapping outside", async ({ page }) => {
+  const drawer = page.locator('[data-slot="mobile-tabs-drawer"]')
+  const tab = drawer.locator('[data-slot="tab-link"]').filter({ hasText: fixture.expected.sourceTitle })
+  const home = drawer.getByRole("button", { name: "Home", exact: true })
+  const homeBox = await home.boundingBox()
+  const box = await tab.boundingBox()
+  expect(homeBox).not.toBeNull()
+  expect(box).not.toBeNull()
+  const point = { x: box!.x + box!.width / 2, y: box!.y + box!.height / 2 }
+
+  await tab.dispatchEvent("pointerdown", {
+    pointerType: "touch",
+    pointerId: 1,
+    isPrimary: true,
+    clientX: point.x,
+    clientY: point.y,
+  })
+  const rename = page.getByRole("menuitem", { name: "Rename", exact: true })
+  await expect(rename).toBeVisible()
+  await expect(drawer).toBeVisible()
+  await tab.filter({ visible: true }).dispatchEvent("pointerup", {
+    pointerType: "touch",
+    pointerId: 1,
+    isPrimary: true,
+    clientX: point.x,
+    clientY: point.y,
+  })
+
+  await page.touchscreen.tap(homeBox!.x + homeBox!.width / 2, homeBox!.y + homeBox!.height / 2)
+  await expect(rename).toBeHidden()
+  await expect(drawer).toBeVisible()
+})
+
+async function touchDrag(
+  page: Page,
+  source: Locator,
+  input: { from: { x: number; y: number }; to: { x: number; y: number } },
+) {
+  const client = await page.context().newCDPSession(page)
+  await client.send("Input.dispatchTouchEvent", {
+    type: "touchStart",
+    touchPoints: [{ ...input.from, id: 1 }],
+  })
+  await client.send("Input.dispatchTouchEvent", {
+    type: "touchMove",
+    touchPoints: [{ x: (input.from.x + input.to.x) / 2, y: (input.from.y + input.to.y) / 2, id: 1 }],
+  })
+  await expect(source).toHaveCount(2)
+  await client.send("Input.dispatchTouchEvent", {
+    type: "touchMove",
+    touchPoints: [{ ...input.to, id: 1 }],
+  })
+  await client.send("Input.dispatchTouchEvent", { type: "touchEnd", touchPoints: [] })
+}
@@ -166,6 +166,45 @@ test.describe("session timeline projection", () => {
    await expect(longNotice.locator("[title]")).toHaveAttribute("title", `Switched to ${longName}`)
    await expect.poll(() => longNotice.evaluate((element) => element.scrollWidth <= element.clientWidth)).toBe(true)
  })
+
+  test("does not repeat a review comment file as an attachment", async ({ page }) => {
+    const message = userMessage([
+      userText("what's goin on here", { id: "prt_user_review_comment" }),
+      {
+        id: "prt_user_review_file",
+        type: "file",
+        mime: "text/plain",
+        filename: "LiveRuntime.ts",
+        url: "file:///repo/LiveRuntime.ts?start=14&end=32",
+      },
+      {
+        id: "prt_user_unrelated_file",
+        type: "file",
+        mime: "text/plain",
+        filename: "notes.txt",
+        url: "data:text/plain;base64,bm90ZXM=",
+      },
+    ])
+    message.metadata = {
+      displayText: "what's goin on here",
+      comments: [
+        {
+          path: "LiveRuntime.ts",
+          comment: "what's goin on here",
+          selection: { startLine: 14, startChar: 0, endLine: 32, endChar: 0 },
+          origin: "review",
+        },
+      ],
+    }
+
+    await setupTimeline(page, { messages: [message, assistantMessage()] })
+
+    const user = page.locator('[data-component="user-message"]')
+    await expect(user.getByText("LiveRuntime.ts:14-32", { exact: true })).toBeVisible()
+    const attachments = user.locator('[data-slot="user-message-attachments"]')
+    await expect(attachments.getByText("LiveRuntime.ts", { exact: true })).toHaveCount(0)
+    await expect(attachments.getByText("notes.txt", { exact: true })).toBeVisible()
+  })
 })

 function patchFile(file: string, status: "added" | "modified" | "deleted") {
@@ -1,6 +1,6 @@
 {
  "name": "@opencode/app",
-  "version": "2.0.8",
+  "version": "2.0.11",
  "description": "",
  "type": "module",
  "exports": {
@@ -46,7 +46,6 @@
    "@sentry/vite-plugin": "catalog:",
    "@tailwindcss/vite": "4.3.3",
    "@types/bun": "catalog:",
-    "@types/luxon": "catalog:",
    "@types/node": "catalog:",
    "@typescript/native-preview": "catalog:",
    "diff": "catalog:",
@@ -88,7 +87,6 @@
    "effect": "catalog:",
    "fuzzysort": "catalog:",
    "ghostty-web": "github:anomalyco/ghostty-web#83c0a07b8628b748aed073b232cb4b52a6ca11c1",
-    "luxon": "catalog:",
    "qr-scanner": "1.4.2",
    "remeda": "catalog:",
    "solid-js": "catalog:",
@@ -1,6 +1,6 @@
 import { describe, expect, test } from "bun:test"
 import type { Prompt } from "@/composer/state"
-import { prependHistoryEntry, type PromptHistoryComment } from "./entry"
+import { prependHistoryEntry, removeHistoryEntry, type PromptHistoryComment } from "./entry"
 import { Schema } from "effect"
 import { PromptHistoryState } from "../schema"
 import { Persistence } from "@/runtime/persistence/schema"
@@ -36,6 +36,24 @@ describe("Composer history", () => {
    expect(dedupedComments).toBe(commentsOnly)
  })

+  test("removeHistoryEntry drops the entry recorded for a prompt and leaves others alone", () => {
+    const image: Prompt = [
+      { type: "text", content: "look", start: 0, end: 4 },
+      { type: "image", id: "img", filename: "big.png", mime: "image/png", blob: { id: "hash", url: "" } },
+    ]
+    const entries = prependHistoryEntry(prependHistoryEntry([], text("earlier")), image, [comment("c1")])
+    expect(entries).toHaveLength(2)
+
+    const untouched = removeHistoryEntry(entries, text("never sent"))
+    expect(untouched).toBe(entries)
+
+    const withoutComments = removeHistoryEntry(entries, image)
+    expect(withoutComments).toBe(entries)
+
+    const removed = removeHistoryEntry(entries, image, [comment("c1")])
+    expect(removed).toEqual(prependHistoryEntry([], text("earlier")))
+  })
+
  test("insertion isolates canonical entries from source mutations", () => {
    const prompt: Prompt = [
      {
@@ -48,6 +48,18 @@ export function prependHistoryEntry(
  return [entry, ...entries].slice(0, max)
 }

+// A send that failed puts its prompt back in the composer, so the entry recorded for it would
+// only duplicate the draft and keep its attachments referenced for as long as history holds it.
+export function removeHistoryEntry(
+  entries: PromptHistoryStoredEntry[],
+  prompt: Prompt,
+  comments: PromptHistoryComment[] = [],
+) {
+  const entry = { prompt, comments } satisfies PromptHistoryEntry
+  const next = entries.filter((item) => !isPromptEqual(item, entry))
+  return next.length === entries.length ? entries : next
+}
+
 function isCommentEqual(commentA: PromptHistoryComment, commentB: PromptHistoryComment) {
  return (
    commentA.path === commentB.path &&
@@ -4,6 +4,7 @@ import { Persist, persisted } from "@/runtime/persistence/storage"
 import {
  clonePromptHistoryComments,
  prependHistoryEntry,
+  removeHistoryEntry,
  type PromptHistoryComment,
  type PromptHistoryStoredEntry,
 } from "./entry"
@@ -13,6 +14,7 @@ import { PromptHistoryState } from "../schema"
 export type ComposerHistoryStore = {
  entries: (mode: "normal" | "shell") => PromptHistoryStoredEntry[]
  add: (prompt: Prompt, mode: "normal" | "shell", comments: PromptHistoryComment[]) => void
+  remove: (prompt: Prompt, mode: "normal" | "shell", comments: PromptHistoryComment[]) => void
 }

 type PromptHistoryState = typeof PromptHistoryState.Type
@@ -32,6 +34,13 @@ function createComposerHistoryStore(
      if (next === current.entries) return
      setCurrent("entries", next)
    },
+    remove(prompt, mode, comments) {
+      const current = mode === "shell" ? shell : normal
+      const setCurrent = mode === "shell" ? setShell : setNormal
+      const next = removeHistoryEntry(current.entries, prompt, comments)
+      if (next === current.entries) return
+      setCurrent("entries", next)
+    },
  }
 }

@@ -56,5 +65,12 @@ export function createComposerHistory() {
      const metadata = clonePromptHistoryComments(comments)
      void ready.then(() => history.add(saved, mode, metadata))
    },
+    remove(prompt: Prompt, mode: "normal" | "shell", comments: PromptHistoryComment[]) {
+      const ready = mode === "shell" ? shellInit : normalInit
+      if (!(ready instanceof Promise)) return history.remove(prompt, mode, comments)
+      const saved = clonePrompt(prompt)
+      const metadata = clonePromptHistoryComments(comments)
+      void ready.then(() => history.remove(saved, mode, metadata))
+    },
  }
 }
@@ -264,6 +264,7 @@ export function createComposerModel(adapter: ComposerAdapter, options?: { queue?
    editor: () => editor,
    queueScroll: () => requestAnimationFrame(() => editor?.scrollIntoView({ block: "nearest" })),
    addToHistory: (value, mode) => controller.addHistory(value, mode),
+    removeFromHistory: (value, mode, comments) => history.remove(value, mode, mode === "shell" ? [] : comments),
    resetHistory: () => controller.resetHistory(),
    setMode: (next) => controller.dispatch({ type: next === "shell" ? "mode.shell" : "mode.normal" }),
    closePopover: () => controller.dispatch({ type: "popover.close" }),
@@ -53,6 +53,7 @@ function submitInput(
  notify = { missingSelection() {}, failed(_kind: "shell" | "command" | "prompt", _error: unknown) {} },
  mode: "normal" | "shell" = "normal",
  commands: () => readonly { name: string }[] | undefined = () => [],
+  history: string[] = [],
 ) {
  return createComposerSubmit({
    adapter,
@@ -60,7 +61,9 @@ function submitInput(
    commands,
    editor: () => undefined,
    queueScroll() {},
-    addToHistory() {},
+    addToHistory: (prompt) => history.push(`add:${prompt.map((part) => ("content" in part ? part.content : part.type)).join("")}`),
+    removeFromHistory: (prompt) =>
+      history.push(`remove:${prompt.map((part) => ("content" in part ? part.content : part.type)).join("")}`),
    resetHistory() {},
    setMode() {},
    closePopover() {},
@@ -533,12 +536,8 @@ describe("Composer submission", () => {
      missingSelection() {},
      failed: () => (attempts.length === 2 ? first.resolve() : second.resolve()),
    }
-    const submission = submitInput(
-      adapter,
-      notify,
-      "normal",
-      () => [],
-    )
+    const history: string[] = []
+    const submission = submitInput(adapter, notify, "normal", () => [], history)

    await submission.submit(new Event("submit"))
    await first.promise
@@ -549,6 +548,8 @@ describe("Composer submission", () => {
    expect(new Set(attempts).size).toBe(1)
    expect(statuses).toEqual(["running", "idle", "running", "idle"])
    expect(state.current()).toMatchObject([{ type: "text", content: text }])
+    // The restored prompt is the draft again, so history does not also keep it (and its attachments).
+    expect(history).toEqual([`add:${text}`, `remove:${text}`, `add:${text}`, `remove:${text}`])
  })

  test("forwards structured mentions to custom commands", async () => {
@@ -32,6 +32,7 @@ type ComposerSubmitInput = {
  editor: () => HTMLDivElement | undefined
  queueScroll: () => void
  addToHistory: (prompt: Prompt, mode: "normal" | "shell") => void
+  removeFromHistory: (prompt: Prompt, mode: "normal" | "shell", comments: PromptHistoryComment[]) => void
  resetHistory: () => void
  setMode: (mode: "normal" | "shell") => void
  closePopover: () => void
@@ -250,6 +251,8 @@ function restoreSubmission(
 ) {
  const restored = submission.restore()
  if (!restored) return false
+  // The prompt is back in the composer; its history entry would only keep attachments referenced.
+  input.removeFromHistory(value.prompt, value.mode, comments)
  restored.target.set(restored.prompt, promptLength(restored.prompt))
  restored.target.mode.set(value.mode)
  restored.target.context.replaceComments(
@@ -3,7 +3,6 @@ import { useDialog } from "@opencode/ui/context/dialog"
 import { Button } from "@opencode/ui/button"
 import { DialogFooter, DialogHeader, DialogTitleGroup, Dialog } from "@opencode/ui/dialog"
 import { skipToken, useQuery, useQueryClient } from "@tanstack/solid-query"
-import { DateTime } from "luxon"
 import { type Accessor, createEffect, createMemo, type JSX, startTransition, untrack } from "solid-js"
 import { notifySessionTabsRemoved } from "@/shell/titlebar/session-events"
 import { useCommand } from "@/shell/commands/command"
@@ -327,19 +326,19 @@ export function homeSessionSearchKey(record: HomeSessionRecord) {
  return `${pathKey(record.session.location.directory)}:${record.session.id}`
 }

+// Calendar day in the local time zone, comparable as a number.
+function localDay(date: Date) {
+  return date.getFullYear() * 10_000 + date.getMonth() * 100 + date.getDate()
+}
+
 function groupSessions(records: HomeSessionRecord[], language: ReturnType<typeof useLanguage>): HomeSessionGroup[] {
-  const now = DateTime.local()
-  const yesterday = now.minus({ days: 1 })
-  const todaySessions = records.filter((record) =>
-    DateTime.fromMillis(record.session.time.updated ?? record.session.time.created).hasSame(now, "day"),
-  )
-  const yesterdaySessions = records.filter((record) =>
-    DateTime.fromMillis(record.session.time.updated ?? record.session.time.created).hasSame(yesterday, "day"),
-  )
-  const olderSessions = records.filter((record) => {
-    const time = DateTime.fromMillis(record.session.time.updated ?? record.session.time.created)
-    return !time.hasSame(now, "day") && !time.hasSame(yesterday, "day")
-  })
+  const now = new Date()
+  const today = localDay(now)
+  const yesterday = localDay(new Date(now.getFullYear(), now.getMonth(), now.getDate() - 1))
+  const day = (record: HomeSessionRecord) => localDay(new Date(record.session.time.updated ?? record.session.time.created))
+  const todaySessions = records.filter((record) => day(record) === today)
+  const yesterdaySessions = records.filter((record) => day(record) === yesterday)
+  const olderSessions = records.filter((record) => day(record) !== today && day(record) !== yesterday)
  const olderTitle =
    todaySessions.length === 0 && yesterdaySessions.length === 0
      ? language.t("sidebar.project.recentSessions")
@@ -65,14 +65,14 @@
  }

  /* Keep the 1000px conversation intact, with 320px for the summary and its gutters.
-     Move only as far as needed; wider panels already have enough space in the margin. */
-  @container session-chat (min-width: 1320px) {
+     When they overlap, center the conversation in the space that remains beside the summary. */
+  @container session-chat (min-width: 1320px) and (width < 1640px) {
    [data-slot="session-chat-panel"][data-summary-open="true"]
      :is([data-timeline-virtual-content], [data-component="session-composer-dock"] > div) {
-      --session-summary-translate: min(0px, calc(50cqi - 820px));
+      --session-summary-translate: -160px;

      &:dir(rtl) {
-        --session-summary-translate: max(0px, calc(820px - 50cqi));
+        --session-summary-translate: 160px;
      }
    }
  }
@@ -1,5 +1,4 @@
 import { type Accessor, createMemo } from "solid-js"
-import { DateTime } from "luxon"
 import { filter, firstBy, flat, groupBy, mapValues, pipe, uniqueBy, values } from "remeda"
 import { createSimpleContext } from "@opencode/ui/context"
 import { useProviders } from "@/providers/catalog/providers"
@@ -9,6 +8,8 @@ export type ModelKey = { providerID: string; modelID: string }

 type Visibility = "show" | "hide"
 const RECENT_LIMIT = 5
+// luxon's diffNow().as("months") used an average month; keep the same window.
+const sixMonths = 6 * 30.436875 * 24 * 60 * 60 * 1000

 function modelKey(model: ModelKey) {
  return `${model.providerID}:${model.modelID}`
@@ -29,27 +30,23 @@ const createModelsController = (directory: Accessor<string | undefined>) => {
    ),
  )

+  // Release dates as epoch ms; an unparseable date is NaN and never counts as recent.
  const release = createMemo(
    () =>
      new Map(
-        available().map((model) => {
-          const parsed = DateTime.fromISO(model.release_date)
-          return [modelKey({ providerID: model.provider.id, modelID: model.id }), parsed] as const
-        }),
+        available().map(
+          (model) => [modelKey({ providerID: model.provider.id, modelID: model.id }), Date.parse(model.release_date)] as const,
+        ),
      ),
  )

  const latest = createMemo(() =>
    pipe(
      available(),
-      filter(
-        (x) =>
-          Math.abs(
-            (release().get(modelKey({ providerID: x.provider.id, modelID: x.id })) ?? DateTime.invalid("invalid"))
-              .diffNow()
-              .as("months"),
-          ) < 6,
-      ),
+      filter((x) => {
+        const released = release().get(modelKey({ providerID: x.provider.id, modelID: x.id })) ?? NaN
+        return Math.abs(Date.now() - released) < sixMonths
+      }),
      groupBy((x) => x.provider.id),
      mapValues((models) =>
        pipe(
@@ -101,9 +98,8 @@ const createModelsController = (directory: Accessor<string | undefined>) => {
    if (state === "hide") return false
    if (state === "show") return true
    if (latestSet().has(key)) return true
-    const date = release().get(key)
-    if (!date?.isValid) return true
-    return false
+    // Models without a parseable release date stay visible.
+    return !Number.isFinite(release().get(key) ?? NaN)
  }

  const setVisibility = (model: ModelKey, state: boolean) => {
@@ -906,6 +906,10 @@ export const dict = {
  "session.browser.replaced": "Browser control moved to another desktop window.",
  "session.browser.suspended": "Browser suspended. Interact with this session to reconnect.",
  "session.browser.address.placeholder": "Enter URL",
+  "session.browser.empty.title": "Enter URL",
+  "session.browser.empty.description": 'Or prompt "Open in the app browser"',
+  "session.browser.failed.title": "URL can't be reached",
+  "session.browser.failed.description": "Check the URL and your connection, then try again.",

  "titlebar.update": "Update",
  "titlebar.tabs": "Tabs",
@@ -20,13 +20,18 @@ export function SessionBrowserPane(props: { browser: ReturnType<typeof createSes
  const command = useCommand()
  const state = props.browser.active
  const address = () => (state()?.url === "about:blank" ? "" : (state()?.url ?? ""))
+  const failed = () => !!state()?.loadError
  const registration = props.browser.registration
  const button = { variant: "ghost", size: "large" } as const
  const [store, setStore] = createStore({
    address: "",
    editing: false,
+    submitted: false,
+    // A submitted navigation the browser has not reported yet; keeps the empty state hidden meanwhile.
+    navigating: false,
    visible: typeof document === "undefined" || document.visibilityState === "visible",
  })
+  const empty = () => !address() && !state()?.loading && !store.navigating
  let surface: HTMLDivElement | undefined
  let addressDisplay: HTMLDivElement | undefined
  let frame: number | undefined
@@ -43,7 +48,7 @@ export function SessionBrowserPane(props: { browser: ReturnType<typeof createSes
      title: language.t("command.browser.reload"),
      category: language.t("command.category.view"),
      keybind: "f5",
-      disabled: !props.visible || !state(),
+      disabled: !props.visible || !address(),
      onSelect: () => {
        const tab = state()
        if (tab) props.browser.command({ type: "reload", tabID: tab.id })
@@ -71,7 +76,9 @@ export function SessionBrowserPane(props: { browser: ReturnType<typeof createSes
    const top = Math.round(rect.top * zoom)
    const right = Math.round(rect.right * zoom)
    const bottom = Math.round(rect.bottom * zoom)
-    const visible = props.visible && store.visible && !dialog.active && !covered(rect)
+    // The desktop page hides blank and loading documents itself; only hide here
+    // while the pane shows its own empty or failed state over the surface.
+    const visible = props.visible && store.visible && !empty() && !failed() && !dialog.active && !covered(rect)
    // The cutout exposes the app backdrop outside the rounded Review card,
    // not the browser surface inside it.
    const color = getComputedStyle(
@@ -107,7 +114,25 @@ export function SessionBrowserPane(props: { browser: ReturnType<typeof createSes
    if (frame === undefined) frame = requestAnimationFrame(tick)
  }

-  createEffect(() => !store.editing && setStore("address", address()))
+  createEffect(on([() => state()?.id, address], () => !store.editing && setStore("address", address())))
+  // Any reported movement, including a rejected or blocked request, ends the submitted navigation.
+  createEffect(
+    on(
+      [() => state()?.id, () => state()?.generation, () => state()?.loading, () => props.browser.error()],
+      () => setStore("navigating", false),
+      { defer: true },
+    ),
+  )
+  // A blocked or rejected submission leaves the page where it was; show that page's URL again.
+  createEffect(
+    on(
+      () => props.browser.error(),
+      (error) => {
+        if (error && !store.editing) setStore("address", address())
+      },
+      { defer: true },
+    ),
+  )
  createEffect(
    on(registration, (current) => {
      // Session routes can change before this pane unmounts. Hide the registration
@@ -123,6 +148,8 @@ export function SessionBrowserPane(props: { browser: ReturnType<typeof createSes
        () => store.visible,
        () => props.visible,
        () => state()?.id,
+        empty,
+        failed,
        registration,
      ],
      () => {
@@ -157,7 +184,7 @@ export function SessionBrowserPane(props: { browser: ReturnType<typeof createSes

  return (
    <aside id="browser-panel" class="relative size-full min-w-0 overflow-hidden bg-v2-background-bg-base flex flex-col">
-      <div class="h-10 shrink-0 flex items-center gap-1 px-2 border-b border-v2-border-border-muted">
+      <div class="h-10 shrink-0 flex items-center gap-1 px-3 border-b border-v2-border-border-muted">
        <For each={["back", "forward"] as const}>
          {(direction) => (
            <Tooltip placement="top" value={language.t(direction === "back" ? "common.goBack" : "common.goForward")}>
@@ -193,7 +220,7 @@ export function SessionBrowserPane(props: { browser: ReturnType<typeof createSes
        >
          <IconButton
            {...button}
-            disabled={!state()}
+            disabled={!state()?.loading && !address()}
            aria-label={language.t(state()?.loading ? "prompt.action.stop" : "error.page.action.reload")}
            onClick={() => {
              const tab = state()
@@ -212,8 +239,13 @@ export function SessionBrowserPane(props: { browser: ReturnType<typeof createSes
          onSubmit={(event) => {
            event.preventDefault()
            const tab = state()
-            if (tab && store.address.trim())
-              props.browser.command({ type: "navigate", tabID: tab.id, url: store.address })
+            const url = store.address.trim()
+            if (!tab) return
+            if (url || failed()) {
+              setStore({ submitted: true, address: url, navigating: true })
+              props.browser.command({ type: "navigate", tabID: tab.id, url: url || "about:blank" })
+            }
+            event.currentTarget.querySelector("input")?.blur()
          }}
        >
          <input
@@ -224,8 +256,14 @@ export function SessionBrowserPane(props: { browser: ReturnType<typeof createSes
            disabled={!state()}
            placeholder={language.t("session.browser.address.placeholder")}
            aria-label={language.t("session.browser.address")}
-            onFocus={() => setStore("editing", true)}
-            onBlur={() => setStore({ editing: false, address: address() })}
+            onFocus={(event) => {
+              setStore("editing", true)
+              event.currentTarget.select()
+            }}
+            onClick={(event) => event.currentTarget.select()}
+            onBlur={() =>
+              setStore({ editing: false, address: store.submitted ? store.address : address(), submitted: false })
+            }
            onInput={(event) => setStore("address", event.currentTarget.value)}
            onScroll={(event) => {
              if (addressDisplay) addressDisplay.scrollLeft = event.currentTarget.scrollLeft
@@ -243,12 +281,27 @@ export function SessionBrowserPane(props: { browser: ReturnType<typeof createSes
          </div>
        </form>
      </div>
-      <Show when={props.browser.error()}>
+      <Show when={props.browser.error() && !failed()}>
        <div class="shrink-0 px-3 py-1.5 text-12-regular text-text-danger-base border-b border-v2-border-border-muted">
          {props.browser.error()}
        </div>
      </Show>
      <div ref={surface} class="min-h-0 flex-1 bg-v2-background-bg-base flex items-center justify-center">
+        <Show when={(empty() || failed()) && !props.browser.suspended()}>
+          {/* Add the 40px toolbar to the file empty state's 160px bottom padding to align their centers. */}
+          <div
+            dir="auto"
+            class="flex size-full flex-col items-center justify-center gap-2 p-6 pb-[200px] text-center text-text-weak"
+          >
+            <Icon name="globe" size="large" class="mb-2 shrink-0" />
+            <div class="text-[13px] font-medium leading-[var(--line-height-compact)] text-text-strong">
+              {language.t(failed() ? "session.browser.failed.title" : "session.browser.empty.title")}
+            </div>
+            <div class="text-13-regular leading-[var(--line-height-base)]">
+              {language.t(failed() ? "session.browser.failed.description" : "session.browser.empty.description")}
+            </div>
+          </div>
+        </Show>
        <Show when={props.browser.suspended()}>
          <p class="px-6 text-center text-13-regular text-v2-text-text-subtle" role="status">
            {language.t("session.browser.suspended")}
@@ -1,6 +1,12 @@
-import { DateTime } from "luxon"
-
 export function createSessionContextFormatter(locale: string) {
+  // The fields luxon's DATETIME_MED preset passed to Intl; output is identical.
+  const dateTime = new Intl.DateTimeFormat(locale, {
+    year: "numeric",
+    month: "short",
+    day: "numeric",
+    hour: "numeric",
+    minute: "numeric",
+  })
  return {
    number(value: number | null | undefined) {
      if (value === undefined) return "—"
@@ -14,7 +20,7 @@ export function createSessionContextFormatter(locale: string) {
    },
    time(value: number | undefined) {
      if (!value) return "—"
-      return DateTime.fromMillis(value).setLocale(locale).toLocaleString(DateTime.DATETIME_MED)
+      return dateTime.format(value)
    },
  }
 }
@@ -1,6 +1,8 @@
 import { children, createMemo, Show } from "solid-js"
 import type { JSX } from "solid-js"
 import { useSortable } from "@dnd-kit/solid/sortable"
+import { Icon } from "@opencode/ui/icon"
+import { IconButton } from "@opencode/ui/icon-button"
 import { Keybind } from "@opencode/ui/keybind"
 import { Tooltip } from "@opencode/ui/tooltip"
 import { Tabs } from "@opencode/ui/tabs"
@@ -69,9 +71,19 @@ export function SortableTab(props: {
              placement="bottom"
              gutter={10}
            >
-              <Tabs.CloseButton
-                class="h-5 w-5"
-                onClick={() => props.onTabClose(props.tab)}
+              <IconButton
+                size="small"
+                variant="ghost-muted"
+                onPointerDown={(event) => {
+                  event.preventDefault()
+                  event.stopPropagation()
+                }}
+                onClick={(event) => {
+                  event.preventDefault()
+                  event.stopPropagation()
+                  props.onTabClose(props.tab)
+                }}
+                icon={<Icon name="xmark-small" />}
                aria-label={language.t("common.closeTab")}
              />
            </Tooltip>
@@ -1,7 +1,8 @@
-import { For, Show, createEffect, createMemo, lazy, on, onCleanup } from "solid-js"
+import { For, Show, createEffect, createMemo, on, onCleanup } from "solid-js"
 import { createStore } from "solid-js/store"
 import { makeEventListener } from "@solid-primitives/event-listener"
 import { Button } from "@opencode/ui/button"
+import { Icon } from "@opencode/ui/icon"
 import { IconButton } from "@opencode/ui/icon-button"
 import { TextInput } from "@opencode/ui/text-input"
 import { showToast } from "@/shell/notifications/toast"
@@ -17,8 +18,6 @@ import { useLanguage } from "@/runtime/i18n/language"
 import { useSettings } from "@/settings/model"
 import { SettingsList } from "@/settings/list"

-const Icon = lazy(() => import("@opencode/ui/icon").then((module) => ({ default: module.Icon })))
-
 const IS_MAC = typeof navigator === "object" && /(Mac|iPod|iPhone|iPad)/.test(navigator.platform)
 const PALETTE_ID = "command.palette"

@@ -1,5 +1,5 @@
 import { describe, expect, test } from "bun:test"
-import { canOpenTabRename, canStartTabDrag, forwardTabRef, isTabCloseTarget } from "./tab-gesture"
+import { canOpenTabRename, forwardTabRef, isTabCloseTarget } from "./tab-gesture"

 describe("titlebar tab gestures", () => {
  test("excludes close controls from tab gestures", () => {
@@ -24,10 +24,4 @@ describe("titlebar tab gestures", () => {
    expect(canOpenTabRename(false, false, false)).toBe(true)
    expect(canOpenTabRename(false, false, true)).toBe(false)
  })
-
-  test("preserves native panning for touch pointers", () => {
-    expect(canStartTabDrag("mouse")).toBe(true)
-    expect(canStartTabDrag("pen")).toBe(true)
-    expect(canStartTabDrag("touch")).toBe(false)
-  })
 })
@@ -4,10 +4,6 @@ export function isTabCloseTarget(target: EventTarget | null) {
  return target instanceof Element && !!target.closest('[data-slot="tab-close"]')
 }

-export function canStartTabDrag(pointerType: string) {
-  return pointerType !== "touch"
-}
-
 export function forwardTabRef(ref: Ref<HTMLDivElement> | undefined, element: HTMLDivElement) {
  if (typeof ref === "function") ref(element)
 }
@@ -9,7 +9,8 @@
  justify-content: center;
 }

-[data-titlebar-tab] {
+[data-titlebar-tab],
+[data-titlebar-tab-action] {
  --tab-base: var(--v2-background-bg-deep);
  --tab-overlay: transparent;
  background: linear-gradient(var(--tab-overlay), var(--tab-overlay)), var(--tab-base);
@@ -68,6 +69,14 @@
  --tab-overlay: var(--v2-overlay-simple-overlay-pressed);
 }

+[data-titlebar-tab-action]:is(:hover, :focus-visible) {
+  --tab-overlay: var(--v2-overlay-simple-overlay-hover);
+}
+
+[data-titlebar-tab-action]:is(:active, [data-state="pressed"]) {
+  --tab-overlay: var(--v2-overlay-simple-overlay-pressed);
+}
+
 [data-titlebar-tab]:is(:hover, [data-state="pressed"]) [data-slot="tab-close"] {
  background: linear-gradient(var(--tab-overlay), var(--tab-overlay)), var(--tab-base);
 }
@@ -328,6 +328,7 @@ export function TabNavItem(props: {

  return (
    <Menu.Context
+      modal={false}
      onOpenChange={(open) => {
        setMenu("open", open)
        if (open) setPopoverOpen(false)
@@ -16,7 +16,7 @@ import { useTabs } from "@/shell/tabs/tabs"
 import { createTabComposerState } from "@/composer/persistence"
 import { base64Encode } from "@opencode/util/encode"
 import { showToast } from "@/shell/notifications/toast"
-import { canStartTabDrag, isTabCloseTarget } from "./tab-gesture"
+import { isTabCloseTarget } from "./tab-gesture"
 import { adjacentTabKey, mergeVisibleTabOrder } from "./tab-order"
 import type { SessionInfo } from "@opencode/client/promise"

@@ -292,9 +292,11 @@ export function TitlebarTabStrip(props: {
        <DragDropProvider
          sensors={[
            PointerSensor.configure({
-              activationConstraints: [new PointerActivationConstraints.Distance({ value: 4 })],
+              activationConstraints: (event) =>
+                event.pointerType === "touch"
+                  ? [new PointerActivationConstraints.Distance({ value: 8 })]
+                  : [new PointerActivationConstraints.Distance({ value: 4 })],
              preventActivation: (event) =>
-                !canStartTabDrag(event.pointerType) ||
                isTabCloseTarget(event.target) ||
                (event.target instanceof Element && !!event.target.closest('[contenteditable="true"]')),
            }),
@@ -313,6 +315,7 @@ export function TitlebarTabStrip(props: {
            if (!source) return
            const tab = props.tabs.find((item) => tabKey(item) === source.id.toString())
            if (!tab) return
+            if (vertical()) return
            const tabEl = source.element?.querySelector<HTMLDivElement>("[data-titlebar-tab]")
            props.onNavigate(tab, tabEl ?? undefined)
          }}
@@ -351,9 +351,10 @@ export function Titlebar(props: {
              >
                <button
                  type="button"
+                  data-titlebar-tab-action
                  data-action="vertical-tabs-home"
                  data-state={layout.route().type === "home" ? "pressed" : undefined}
-                  class="group mb-1 flex h-7 w-full shrink-0 items-center gap-1.5 rounded-[6px] ps-1.5 pe-2 text-[13px] leading-4 text-v2-text-text-faint hover:bg-v2-background-bg-layer-02 hover:text-v2-text-text-base data-[state=pressed]:bg-v2-background-bg-layer-02 data-[state=pressed]:text-v2-text-text-base"
+                  class="group mb-1 flex h-7 w-full shrink-0 items-center gap-1.5 rounded-[6px] ps-1.5 pe-2 text-[13px] leading-4 text-v2-text-text-faint hover:text-v2-text-text-base data-[state=pressed]:text-v2-text-text-base"
                  onClick={toggleHome}
                  aria-label={language.t("home.title")}
                  aria-pressed={layout.route().type === "home"}
@@ -650,8 +651,9 @@ export function Titlebar(props: {
                            {homeButton(true)}
                            <button
                              type="button"
+                              data-titlebar-tab-action
                              data-action="vertical-tabs-new-session"
-                              class="group flex h-7 w-full shrink-0 items-center gap-1.5 rounded-[6px] ps-1.5 pe-2 text-[13px] leading-4 text-v2-text-text-faint hover:bg-v2-background-bg-layer-02 hover:text-v2-text-text-base"
+                              class="group flex h-7 w-full shrink-0 items-center gap-1.5 rounded-[6px] ps-1.5 pe-2 text-[13px] leading-4 text-v2-text-text-faint hover:text-v2-text-text-base"
                              onClick={openNewTab}
                              aria-label={language.t("command.session.new")}
                            >
@@ -36,17 +36,17 @@ export function ErrorOverlay(props: { component: string; error: unknown; onClose
      <Dialog centered onClose={props.onClose}>
        <box maxHeight={Math.max(1, dimensions().height - 3)} paddingX={2} paddingBottom={1} gap={1}>
          <box flexDirection="row" justifyContent="space-between" flexShrink={0}>
-            <text fg={theme.text.feedback.error.default} attributes={TextAttributes.BOLD}>
+            <text fg={theme.text.feedback.error.base} attributes={TextAttributes.BOLD}>
              Error while hot reloading
            </text>
-            <text fg={theme.text.subdued} onMouseUp={props.onClose}>
+            <text fg={theme.text.muted} onMouseUp={props.onClose}>
              esc
            </text>
          </box>
-          <text maxHeight={Math.max(1, dimensions().height - 9)} fg={theme.text.default}>
+          <text maxHeight={Math.max(1, dimensions().height - 9)} fg={theme.text.base}>
            {props.error instanceof Error ? props.error.message : String(props.error)}
          </text>
-          <text flexShrink={0} fg={theme.text.subdued}>
+          <text flexShrink={0} fg={theme.text.muted}>
            {props.component} · Fix the component and save to retry.
          </text>
        </box>
@@ -1,7 +1,7 @@
 {
  "$schema": "https://json.schemastore.org/package.json",
  "name": "@opencode/cli",
-  "version": "2.0.8",
+  "version": "2.0.11",
  "type": "module",
  "license": "MIT",
  "bin": {
@@ -0,0 +1,120 @@
+#!/usr/bin/env bun
+import { Script } from "@opencode/script"
+import { $ } from "bun"
+import { mkdir, rm } from "node:fs/promises"
+import path from "node:path"
+import { fileURLToPath } from "node:url"
+import { UpdateArtifact } from "../../../script/update-artifact"
+
+if (Script.channel !== "beta" && Script.channel !== "latest") {
+  throw new Error("Homebrew publishing requires the beta or latest channel")
+}
+const valid =
+  Script.channel === "beta"
+    ? /^\d+\.\d+\.\d+-beta[.-]\d+(?:\.\d+)?$/.test(Script.version)
+    : /^\d+\.\d+\.\d+$/.test(Script.version)
+if (!valid) throw new Error(`Expected a ${Script.channel} release version`)
+
+const dir = fileURLToPath(new URL("..", import.meta.url))
+const root = path.resolve(process.env.OPENCODE_CLI_DIST ?? path.join(dir, "dist"))
+const outdir = path.join(root, "homebrew-tap")
+const dryRun = process.argv.includes("--dry-run")
+const name = Script.channel === "beta" ? "opencode-beta" : "opencode-v2"
+const formulaClass = Script.channel === "beta" ? "OpencodeBeta" : "OpencodeV2"
+
+const targets = await Promise.all(
+  [
+    { name: "darwin-arm64", archive: "zip" },
+    { name: "darwin-x64-baseline", archive: "zip" },
+    { name: "linux-arm64", archive: "tar.gz" },
+    { name: "linux-x64-baseline", archive: "tar.gz" },
+  ].map(async (target) => {
+    const filename = `opencode-${target.name}.${target.archive}`
+    const file = Bun.file(path.join(root, filename))
+    if (!(await file.exists()) || !file.size) throw new Error(`Missing Homebrew archive: ${filename}`)
+    const sha256 = new Bun.CryptoHasher("sha256")
+    for await (const chunk of file.stream()) sha256.update(chunk)
+    return {
+      ...target,
+      url: `https://opencode.ai/files/bin/${encodeURIComponent(Script.version)}/${filename}`,
+      sha256: sha256.digest("hex"),
+    }
+  }),
+)
+
+await rm(outdir, { recursive: true, force: true })
+if (dryRun) await mkdir(outdir, { recursive: true })
+if (!dryRun) {
+  const token = process.env.GITHUB_TOKEN
+  if (!token) throw new Error("GITHUB_TOKEN is required to update the Homebrew tap")
+  await $`git clone ${`https://x-access-token:${token}@github.com/anomalyco/homebrew-tap.git`} ${outdir}`
+  await $`git checkout -B master`.cwd(outdir)
+}
+
+const target = (name: string) => {
+  const result = targets.find((item) => item.name === name)
+  if (!result) throw new Error(`Missing Homebrew target: ${name}`)
+  return result
+}
+const macArm = target("darwin-arm64")
+const macIntel = target("darwin-x64-baseline")
+const linuxArm = target("linux-arm64")
+const linuxIntel = target("linux-x64-baseline")
+
+await Bun.write(
+  path.join(outdir, `${name}.rb`),
+  [
+    "# typed: false",
+    "# frozen_string_literal: true",
+    "",
+    `class ${formulaClass} < Formula`,
+    `  desc "OpenCode V2${Script.channel === "beta" ? " beta" : ""} - the AI coding agent for the terminal"`,
+    '  homepage "https://github.com/anomalyco/opencode"',
+    `  version "${Script.version}"`,
+    '  license "MIT"',
+    "",
+    '  depends_on "ripgrep"',
+    '  conflicts_with "opencode", because: "both install an opencode binary"',
+    "",
+    "  on_macos do",
+    "    if Hardware::CPU.arm?",
+    `      url "${macArm.url}"`,
+    `      sha256 "${macArm.sha256}"`,
+    "    else",
+    `      url "${macIntel.url}"`,
+    `      sha256 "${macIntel.sha256}"`,
+    "    end",
+    "  end",
+    "",
+    "  on_linux do",
+    "    if Hardware::CPU.arm?",
+    `      url "${linuxArm.url}"`,
+    `      sha256 "${linuxArm.sha256}"`,
+    "    else",
+    `      url "${linuxIntel.url}"`,
+    `      sha256 "${linuxIntel.sha256}"`,
+    "    end",
+    "  end",
+    "",
+    "  def install",
+    '    bin.install "opencode"',
+    "  end",
+    "end",
+    "",
+  ].join("\n"),
+)
+console.log(`Prepared ${name} ${Script.version} in ${outdir}`)
+if (dryRun) process.exit(0)
+
+await $`git add ${name + ".rb"}`.cwd(outdir)
+if ((await $`git diff --cached --quiet`.cwd(outdir).nothrow()).exitCode !== 0) {
+  await $`git commit -m ${`chore: update ${name} to ${Script.version}`}`.cwd(outdir)
+  await $`git push origin master`.cwd(outdir)
+}
+await UpdateArtifact.publish({
+  channel: Script.channel,
+  name: "cli",
+  distribution: "homebrew",
+  version: Script.version,
+  metadata: { package: `anomalyco/tap/${name}` },
+})
@@ -149,6 +149,10 @@ if (Script.channel === "latest" && Script.release && !dryRun) {

 if ((Script.channel === "beta" || Script.channel === "latest") && Script.release) {
  await $`bun ./script/publish-aur.ts ${dryRun ? ["--dry-run"] : []}`.env({ ...process.env, OPENCODE_CLI_DIST: root })
+  await $`bun ./script/publish-homebrew.ts ${dryRun ? ["--dry-run"] : []}`.env({
+    ...process.env,
+    OPENCODE_CLI_DIST: root,
+  })
 }

 async function archive(bin: string, target: string, binary: string, directory: string) {
@@ -1,7 +1,8 @@
 #!/usr/bin/env bun

 import { NodeRuntime, NodeServices } from "@effect/platform-node"
-import { Effect } from "effect"
+import { Cause, Effect } from "effect"
+import { getErrorReported } from "effect/Runtime"
 import { Commands } from "./commands/commands"
 import { Runtime } from "./framework/runtime"
 import { Observability } from "@opencode/util/observability"
@@ -130,5 +131,15 @@ Effect.gen(function* () {
  Effect.provide(NodeServices.layer),
  Effect.scoped,
  Effect.tap(() => Effect.sync(() => process.exit(process.exitCode ?? 0))),
-  NodeRuntime.runMain,
+  // runMain's default reporter logs the fatal cause to stdout. Write it to stderr instead: the
+  // desktop and `Service.ensure` only capture stderr from `serve --service`, so this is the only
+  // channel through which a startup failure's reason reaches the user.
+  Effect.tapCause((cause) =>
+    Effect.sync(() => {
+      if (Cause.hasInterruptsOnly(cause)) return
+      if (!getErrorReported(Cause.squash(cause))) return
+      process.stderr.write(Cause.pretty(cause) + "\n")
+    }),
+  ),
+  NodeRuntime.runMain({ disableErrorReporting: true }),
 )
@@ -1,17 +1,22 @@
 import { Global } from "@opencode/util/global"
 import { AppProcess } from "@opencode/util/process"
 import { OPENCODE_ARTIFACT, OPENCODE_CHANNEL, OPENCODE_LOCAL, OPENCODE_VERSION } from "../version"
-import { Context, Duration, Effect, FileSystem, Layer, Ref } from "effect"
+import { Context, Duration, Effect, FileSystem, Layer, Option, Ref, Schema } from "effect"
 import { ChildProcess } from "effect/unstable/process"
 import { parse, type ParseError } from "jsonc-parser"
 import path from "node:path"
 import { action, parseReleaseVersion, type Policy } from "./updater-action"

-export const methods = ["curl", "npm", "pnpm", "bun", "yarn"] as const
+export const methods = ["curl", "npm", "pnpm", "bun", "yarn", "vp", "brew"] as const
+
 export type Method = (typeof methods)[number]
 export type RunResult = { readonly type: "available" | "installed"; readonly version: string }
 export type CheckResult = RunResult | { readonly type: "unavailable"; readonly message: string }

+const decodeVpPackages = Schema.decodeUnknownOption(
+  Schema.fromJsonString(Schema.Array(Schema.Struct({ name: Schema.String }))),
+)
+
 export interface Interface {
  readonly run: (onInstall?: (version: string) => void) => Effect.Effect<RunResult | undefined>
  readonly check: () => Effect.Effect<CheckResult | undefined, Error>
@@ -96,6 +101,13 @@ const make = Effect.gen(function* () {
      process.platform === "win32" ? "opencode.exe" : "opencode",
    )
    if (path.resolve(process.execPath) === path.resolve(binary)) return "curl"
+    const executable = yield* fs.realPath(process.execPath).pipe(Effect.orElseSucceed(() => process.execPath))
+    if (
+      ["opencode-beta", "opencode-v2"].some((name) =>
+        executable.includes(`${path.sep}Cellar${path.sep}${name}${path.sep}`),
+      )
+    )
+      return "brew"
    if (!installedPackage) return

    const checks: ReadonlyArray<{ method: Method; command: string[] }> = [
@@ -103,22 +115,30 @@ const make = Effect.gen(function* () {
      { method: "pnpm", command: ["pnpm", "list", "-g", "--depth=0", installedPackage] },
      { method: "bun", command: ["bun", "pm", "ls", "-g"] },
      { method: "yarn", command: ["yarn", "global", "list"] },
+      { method: "vp", command: ["vp", "list", "-g", "--json", installedPackage] },
    ]
    const results = yield* Effect.forEach(
      checks,
      (check) => exec(check.command).pipe(Effect.map((result) => ({ check, result }))),
      { concurrency: "unbounded" },
    )
-    return results.find((result) => result.result.stdout.includes(installedPackage))?.check.method
+    return results.find((result) => {
+      if (result.check.method !== "vp") return result.result.stdout.includes(installedPackage)
+      // Vite+ repeats the filter in its successful no-match message, so substring detection would be a false positive.
+      return Option.exists(decodeVpPackages(result.result.stdout), (packages) =>
+        packages.some((item) => item.name === installedPackage),
+      )
+    })?.check.method
  })

  const removal = (method: Method) => {
-    if (method === "curl" || !installedPackage) return undefined
+    if (method === "curl" || method === "brew" || !installedPackage) return undefined
    const commands = {
      npm: ["npm", "uninstall", "--global", installedPackage],
      pnpm: ["pnpm", "remove", "--global", installedPackage],
      bun: ["bun", "remove", "--global", installedPackage],
      yarn: ["yarn", "global", "remove", installedPackage],
+      vp: ["vp", "uninstall", "-g", installedPackage],
    }
    const command = commands[method]
    return {
@@ -133,11 +153,12 @@ const make = Effect.gen(function* () {
    }
  }

-  const release = Effect.fnUntraced(function* () {
+  const release = Effect.fnUntraced(function* (method?: Method) {
+    const distribution = method === "brew" ? "homebrew" : "npm"
    const response = yield* Effect.tryPromise({
      try: (signal) =>
        fetch(
-          `https://opencode.ai/update/api/${encodeURIComponent(channel)}/${encodeURIComponent(OPENCODE_ARTIFACT)}/npm?current=${encodeURIComponent(OPENCODE_VERSION)}`,
+          `https://opencode.ai/update/api/${encodeURIComponent(channel)}/${encodeURIComponent(OPENCODE_ARTIFACT)}/${distribution}?current=${encodeURIComponent(OPENCODE_VERSION)}`,
          {
            signal: AbortSignal.any([signal, AbortSignal.timeout(10_000)]),
          },
@@ -153,7 +174,11 @@ const make = Effect.gen(function* () {
    return { package: data.metadata.package, version: data.version }
  })

-  const latest = () => release().pipe(Effect.map((data) => data.version))
+  const latest = () =>
+    method().pipe(
+      Effect.flatMap(release),
+      Effect.map((data) => data.version),
+    )

  const temporaryDirectory = (prefix: string) =>
    Effect.acquireRelease(fs.makeTempDirectory({ directory: global.cache, prefix }), (directory) =>
@@ -163,12 +188,12 @@ const make = Effect.gen(function* () {
  const upgrade = Effect.fnUntraced(function* (method: Method, input: string) {
    if (!parseReleaseVersion(input)) return yield* Effect.fail(new Error(`Invalid version: ${input}`))
    const version = input.trim().replace(/^v/, "")
-    const packageName = (yield* release()).package
+    const packageName = (yield* release(method)).package
    const target = `${packageName}@${version}`
    if (installedPackage && packageName !== installedPackage && (method === "pnpm" || method === "yarn")) {
      return yield* Effect.fail(new Error(`Reinstall ${target} with ${method} to migrate from ${installedPackage}.`))
    }
-    const commands: Record<Exclude<Method, "bun" | "curl">, string[]> = {
+    const commands: Record<Exclude<Method, "bun" | "curl" | "brew">, string[]> = {
      // Keep the old package: uninstalling it can unlink the replacement command.
      npm: [
        "npm",
@@ -182,6 +207,10 @@ const make = Effect.gen(function* () {
      ],
      pnpm: ["pnpm", "add", "--global", `--allow-build=${packageName}`, target],
      yarn: ["yarn", "global", "add", target],
+      vp:
+        installedPackage && packageName !== installedPackage
+          ? ["vp", "install", "-g", "--force", target]
+          : ["vp", "update", "-g", target],
    }
    const result = yield* Effect.scoped(
      Effect.gen(function* () {
@@ -202,6 +231,7 @@ const make = Effect.gen(function* () {
          if (download.code !== 0) return download
          return yield* exec(["bash", installer, "--version", version, "--no-modify-path"], "5 minutes")
        }
+        if (method === "brew") return yield* exec(["brew", "upgrade", packageName], "5 minutes")
        return yield* exec(commands[method], "5 minutes")
      }),
    ).pipe(Effect.mapError((cause) => new Error(`Failed to update with ${method}`, { cause })))
@@ -19,6 +19,7 @@ function fixture(
  } = () => ({}),
  name = "@opencode/cli",
  failCleanup = false,
+  releasePackage = name,
 ) {
  return Effect.gen(function* () {
    const fs = yield* FileSystem.FileSystem
@@ -34,7 +35,7 @@ function fixture(
    yield* Effect.acquireRelease(
      Effect.sync(() =>
        spyOn(globalThis, "fetch").mockImplementation(
-          Object.assign(async () => Response.json({ version: "2.3.4", metadata: { package: name } }), {
+          Object.assign(async () => Response.json({ version: "2.3.4", metadata: { package: releasePackage } }), {
            preconnect: fetch.preconnect,
          }),
        ),
@@ -106,6 +107,7 @@ const installs = [
    command: ["pnpm", "add", "--global", "--allow-build=@opencode/cli", "@opencode/cli@2.3.4-beta.1"],
  },
  { method: "yarn", command: ["yarn", "global", "add", "@opencode/cli@2.3.4-beta.1"] },
+  { method: "vp", command: ["vp", "update", "-g", "@opencode/cli@2.3.4-beta.1"] },
 ] as const

 installs.forEach(({ method, command }) => {
@@ -117,6 +119,25 @@ installs.forEach(({ method, command }) => {
    }),
  )
 })
+
+it.live("vp force-installs a renamed V2 package that replaces the existing binary owner", () =>
+  Effect.gen(function* () {
+    const test = yield* fixture(() => ({}), "@opencode/cli", false, "@opencode/cli-node")
+    yield* test.updater.upgrade("vp", "v2.3.4-beta.1")
+    expect(test.commands).toEqual([["vp", "install", "-g", "--force", "@opencode/cli-node@2.3.4-beta.1"]])
+  }),
+)
+
+it.live("vp removes the package from its managed global store", () =>
+  Effect.gen(function* () {
+    const test = yield* fixture()
+    const removal = test.updater.removal("vp")
+    if (!removal) return yield* Effect.die("Expected vp removal command")
+    expect(removal.command).toEqual(["vp", "uninstall", "-g", "@opencode/cli"])
+    yield* removal.run
+    expect(test.commands).toEqual([["vp", "uninstall", "-g", "@opencode/cli"]])
+  }),
+)
 ;[0, 1].forEach((exitCode) => {
  it.live(`bun isolates and removes its install cache after exit ${exitCode}`, () =>
    Effect.gen(function* () {
@@ -200,11 +221,19 @@ it.live("install failures expose stderr and process errors do not report success
    expect(missing.commands).toHaveLength(1)
  }),
 )
-;(["npm", "pnpm", "bun", "yarn", undefined] as const).forEach((method) => {
+;(["npm", "pnpm", "bun", "yarn", "vp", undefined] as const).forEach((method) => {
  it.live(`method detection identifies ${method ?? "an unknown installation"} using the V2 package`, () =>
    Effect.gen(function* () {
      const test = yield* fixture((command) => ({
-        stdout: Buffer.from(command.command === method ? "@opencode/cli@2.3.4" : "opencode-ai@1.0.0"),
+        stdout: Buffer.from(
+          command.command === method
+            ? method === "vp"
+              ? JSON.stringify([{ name: "@opencode/cli", version: "2.3.4" }])
+              : "@opencode/cli@2.3.4"
+            : command.command === "vp"
+              ? "[]"
+              : "opencode-ai@1.0.0",
+        ),
      }))
      expect(yield* test.updater.method()).toBe(method)
      expect(test.commands).toEqual([
@@ -212,6 +241,7 @@ it.live("install failures expose stderr and process errors do not report success
        ["pnpm", "list", "-g", "--depth=0", "@opencode/cli"],
        ["bun", "pm", "ls", "-g"],
        ["yarn", "global", "list"],
+        ["vp", "list", "-g", "--json", "@opencode/cli"],
      ])
    }),
  )
@@ -225,7 +255,16 @@ it.live("method detection tolerates unavailable package managers", () =>
        : { error: new AppProcess.AppProcessError({ command: command.command }) },
    )
    expect(yield* test.updater.method()).toBe("yarn")
-    expect(test.commands).toHaveLength(4)
+    expect(test.commands).toHaveLength(5)
+  }),
+)
+
+it.live("vp detection ignores no-match output that repeats the package name", () =>
+  Effect.gen(function* () {
+    const test = yield* fixture((command) => ({
+      stdout: Buffer.from(command.command === "vp" ? "No global packages matching '@opencode/cli'." : ""),
+    }))
+    expect(yield* test.updater.method()).toBeUndefined()
  }),
 )

@@ -265,13 +304,16 @@ if (typeof OPENCODE_CLI_NAME === "string" && OPENCODE_CLI_NAME === "opencode2-no
      expect(yield* test.updater.method()).toBe("npm")
      yield* test.updater.upgrade("npm", "v2.3.4")
      yield* test.updater.upgrade("pnpm", "v2.3.4")
+      yield* test.updater.upgrade("vp", "v2.3.4")
      expect(test.commands).toEqual([
        ["npm", "list", "-g", "--depth=0", "@opencode/cli-node"],
        ["pnpm", "list", "-g", "--depth=0", "@opencode/cli-node"],
        ["bun", "pm", "ls", "-g"],
        ["yarn", "global", "list"],
+        ["vp", "list", "-g", "--json", "@opencode/cli-node"],
        ["npm", "install", "--global", "@opencode/cli-node@2.3.4"],
        ["pnpm", "add", "--global", "--allow-build=@opencode/cli-node", "@opencode/cli-node@2.3.4"],
+        ["vp", "update", "-g", "@opencode/cli-node@2.3.4"],
      ])
    }),
  )
@@ -35,6 +35,12 @@ describe("upgrade command", () => {
    expect(result.events).toEqual([{ method: "bun", version: "2.0.0" }])
  })

+  test("accepts vp as an explicit installation method", async () => {
+    const result = await cli(["2.0.0", "--method", "vp"])
+    expect(result.exitCode).toBe(0)
+    expect(result.events).toEqual([{ method: "vp", version: "2.0.0" }])
+  })
+
  test("skips the already installed version", async () => {
    const result = await cli(["v0.0.0-beta-old"])
    expect(result.exitCode).toBe(0)
@@ -50,7 +56,7 @@ describe("upgrade command", () => {
  })

  test("rejects unsupported methods before attempting an upgrade", async () => {
-    const result = await cli(["--method", "brew"])
+    const result = await cli(["--method", "apt"])
    expect(result.exitCode).not.toBe(0)
    expect(result.events).toEqual([])
  })
@@ -1,7 +1,7 @@
 {
  "$schema": "https://json.schemastore.org/package.json",
  "name": "@opencode/client",
-  "version": "2.0.8",
+  "version": "2.0.11",
  "type": "module",
  "license": "MIT",
  "repository": {
@@ -1,9 +1,27 @@
 #!/usr/bin/env bun

 import { $ } from "bun"
+import path from "node:path"
 import { fileURLToPath } from "node:url"

 process.chdir(fileURLToPath(new URL("..", import.meta.url)))

 await $`rm -rf dist`
 await $`bun tsc -p tsconfig.build.json`
+const root = path.resolve("src")
+const result = await Bun.build({
+  entrypoints: await Array.fromAsync(new Bun.Glob("**/*.ts").scan({ cwd: root, absolute: true })).then((files) =>
+    files.filter((file) => !file.endsWith(".d.ts")),
+  ),
+  root,
+  outdir: "dist",
+  target: "node",
+  format: "esm",
+  packages: "external",
+  splitting: true,
+  naming: {
+    entry: "[dir]/[name].[ext]",
+    chunk: "chunks/[name]-[hash].[ext]",
+  },
+})
+if (!result.success) throw new AggregateError(result.logs, "Failed to build Client")
@@ -131,7 +131,9 @@ export const ensure = Effect.fn("service.ensure")(function* (options: EnsureOpti
  }).pipe(
    Effect.repeat({
      until: Option.isSome,
-      schedule: Schedule.max([Schedule.spaced(timing.pollInterval), Schedule.recurs(timing.attempts)]),
+      // Probes run sequentially, so a slow probe stretches each iteration; bound the loop by wall clock
+      // like the Promise variant rather than by attempt count.
+      schedule: Schedule.spaced(timing.pollInterval).pipe(Schedule.upTo({ duration: timing.promiseTimeout })),
    }),
    Effect.ensuring(Effect.sync(() => contenders.forEach((contender) => contender.release()))),
  )
@@ -456,6 +456,10 @@ export type V2EventServerConnected = {
  data: {}
 }

+export type ModelSettings = { compaction?: ProviderCompaction } & { [x: string]: any }
+
+export type ConfigModelSettings = { compaction?: ProviderCompaction } & { [x: string]: JsonValue | null }
+
 export type ProviderSettings = {
  timeout?: number | false
  chunkTimeout?: number
@@ -1656,19 +1660,19 @@ export type SessionInboxMove = {
  payload: SessionInboxMovePayload
 }

+export type ModelVariant = {
+  id: string
+  settings?: ModelSettings
+  headers?: { [x: string]: string }
+  body?: { [x: string]: any }
+}
+
 export type ProviderRequest = {
  settings: ProviderSettings
  headers: { [x: string]: string }
  body: { [x: string]: any }
 }

-export type ModelVariant = {
-  id: string
-  settings?: ProviderSettings
-  headers?: { [x: string]: string }
-  body?: { [x: string]: any }
-}
-
 export type ProviderInfo = {
  id: string
  canonical?: string
@@ -1898,7 +1902,7 @@ export type ModelInfo = {
  name: string
  compatibility?: ModelCompatibility
  package?: string
-  settings?: ProviderSettings
+  settings?: ModelSettings
  headers?: { [x: string]: string }
  body?: { [x: string]: any }
  capabilities: ModelCapabilities
@@ -2107,13 +2111,13 @@ export type ConfigEntry =
                name?: string
                compatibility?: ModelCompatibility
                package?: string
-                settings?: ConfigProviderSettings
+                settings?: ConfigModelSettings
                headers?: { [x: string]: string }
                body?: { [x: string]: JsonValue }
                capabilities?: ModelCapabilities
                variants?: Array<{
                  id: string
-                  settings?: ConfigProviderSettings
+                  settings?: ConfigModelSettings
                  headers?: { [x: string]: string }
                  body?: { [x: string]: JsonValue }
                }>
@@ -1,6 +1,5 @@
 export type EnsureTiming = {
  readonly pollInterval: number
-  readonly attempts: number
  readonly requestTimeout: number
  readonly spawnDelay: number
  readonly maxSpawnDelay: number
@@ -11,9 +10,11 @@ export type EnsureTiming = {

 const timings = new WeakMap<object, EnsureTiming>()

+// A freshly spawned service registers in ~250 ms, so the poll cadence is a large share of the
+// time a client waits for it. Probes are sequential, so the wait between them only matters while
+// the connection is refused; both variants give up after promiseTimeout of wall-clock time.
 export const defaultEnsureTiming: EnsureTiming = {
-  pollInterval: 100,
-  attempts: 1_200,
+  pollInterval: 25,
  requestTimeout: 2_000,
  spawnDelay: 5_000,
  maxSpawnDelay: 30_000,
@@ -2,7 +2,6 @@ import { withEnsureTiming } from "../../src/service-timing"

 const timing = {
  pollInterval: 20,
-  attempts: 120,
  requestTimeout: 100,
  spawnDelay: 200,
  maxSpawnDelay: 1_200,
@@ -6,6 +6,8 @@
 - Tool schemas are the model-facing Interface. Keep arguments minimal and natural to the operation; never add unrelated IDs as ambient capability tokens.
 - State model-visible diagnostics, logs, tool descriptions, and instructions directly. The execution context is already clear; do not repeat `Code Mode` or `CodeMode` unless the distinction is necessary.
 - When interpreter behavior or support changes, update `interpreter-support.md` and direct tests in the same PR.
+- Program values are `Value` (`src/interpreter/objects.ts`); host values are `unknown` and are copied in at the boundaries (`fromHost`, `fromJson`). Do not widen program-facing signatures back to `unknown`.
+- A built-in kind of object is one `Obj` subclass (`Wrapper` for host-backed data such as Date or Map, `Opaque` for machinery such as functions and promises) that overrides `tag`, `toString`, `toPrimitive`, `inspect`, `toHost`, and `iterator` as needed. Do not add `instanceof` ladders over the built-in classes elsewhere; ask the object.

 ## OpenAPI

@@ -13,8 +13,8 @@ The idea of code mode was originally introduced by Cloudflare. See

 ## How it differs from JavaScript

- **Only supported APIs are available.** Programs can use the provided tools and supported JavaScript built-ins. APIs
-  such as `fetch`, timers, `process`, filesystem access, imports, and modules are unavailable.
+- **Only supported APIs are available.** Programs can use the provided tools, supported JavaScript built-ins, and the
+  globals the host adds through extensions. Timers, `process`, filesystem access, imports, and modules are unavailable.
 - **Unfinished work is interrupted.** Tool calls and async functions start when called. When the program finishes,
  anything still running is interrupted. Unhandled rejections from un-awaited promises are returned as warnings.
 - **REPL-style results.** Without an explicit `return`, the final top-level expression becomes the result. `undefined`
@@ -94,11 +94,19 @@ receive `{ extension, name, args }`. An `after` hook also receives how the call
 `failure` with its error, or `interrupted`). A failing `before` hook denies the call, and the program catches the
 failure as a thrown error.

-### `Values`
+### `Extension.make`

-`Values` exports the runtime's non-JSON value classes: `Values.URL`, `Values.URLSearchParams`, `Values.Date`,
-`Values.RegExp`, `Values.Map`, `Values.Set`, and `Values.Promise`. The interpreter recognizes these by class; a
-program's `new URL(...)` is a `Values.URL` wrapping the host `URL`. `Values.isValue` narrows to the data-like kinds.
+Extensions are host functions a program calls directly as globals, such as `fetch`. Unlike tools they are not in the
+catalog, not counted against `maxToolCalls`, and not described to the model; the host decides what they mean.
+
+```ts
+const web = Extension.make({ name: "web", globals: { fetch: (url: string) => globalThis.fetch(url) } })
+const runtime = CodeMode.make({ tools, extensions: [web] })
+```
+
+Every value crossing in either direction is converted, never shared: arguments come in as copies, results go out as
+copies, and a function inside a result is callable the same way. A global that shadows a built-in or another
+extension throws at `CodeMode.make`.

 ### OpenAPI tools

@@ -15,8 +15,7 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 ## Source and execution model

 - [x] JavaScript parsed with the latest syntax accepted by Acorn, then restricted by the interpreter allowlist.
- [x] Erasable TypeScript syntax, including type annotations, type declarations, assertions, and non-null assertions.
-      TypeScript is transpiled first; the emitted JavaScript must still use the supported subset.
+      TypeScript-only syntax is rejected rather than stripped before execution.
 - [x] Top-level `await` and `return` through the program's implicit async-function scope.
 - [x] Explicit `return`, final top-level expression as a REPL-style result, and `null` when no value is produced.
 - [x] The host boundary is `JSON.stringify` plus a short table. The program result and tool arguments cross as
@@ -25,11 +24,11 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
      and Map, RegExp, and generators serialize as `{}`. A bare `undefined` result is `null`.
      Tool results come back the way `JSON.parse(JSON.stringify(result))` would. The table, where a value cannot
      be JSON but what the program meant is clear: a promise is awaited (a rejection fails the program), a Set
-      crosses as an array, a URLSearchParams as its query string, an Error as `{ name, message, ...own }`, a
+      crosses as an array, a URLSearchParams as its query string, an Error as `{ name, message, ...own enumerable }`, a
      Uint8Array is rejected with a hint to encode as text, and own `__proto__` keys are dropped so merging tool
      inputs or results cannot replace a prototype. In-program `JSON.stringify` keeps JS behavior except for the
      Error form and a promise, which is a `TypeError` with an await hint rather than a silent `{}`.
- [x] Live Date, RegExp, Map, Set, URL, URLSearchParams, and Uint8Array values inside CodeMode.
+- [x] Live Date, RegExp, Map, Set, URL, URLSearchParams, Headers, and Uint8Array values inside CodeMode.
 - [x] Tool calls through the host-provided `tools` tree only.
 - [x] The global `search(...)` built-in: synchronous tool discovery that counts as an admitted tool call and is
      shadowable by program declarations like other globals.
@@ -39,16 +38,17 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
      10,000,000 elements (`Array(n)`, `length =`, `Array.from`, `split`, `matchAll`, `concat`, `flat`; below the JS
      maximum of 2^32 - 1), and 10,000 pending promises at once. Exceeding one throws a `RangeError`. A single regular
      expression match can still run long on a pathological pattern; the host regex engine has no interrupt hook.
- [ ] Strict-mode early errors: duplicate parameter names, `yield` as an identifier, and a trailing comma after a
-      rest parameter are accepted unless the program itself begins with `"use strict"`.
- [ ] Valid JavaScript rejected by TypeScript transpilation before interpretation, such as `in` inside a destructuring
-      default in a `for...of` head and Unicode-escaped keywords.
+- [x] A trailing comma after a rest parameter is a syntax error, with or without `"use strict"`.
+- [x] A program that begins with `"use strict"` rejects `yield` as an identifier and duplicate parameter names at
+      parse time. Without it, `yield` is an ordinary binding.
+- [ ] Duplicate parameter names in non-strict code throw when the function is called, instead of binding the last
+      parameter as JavaScript does.

 ## Values and literals

 - [x] `null`, `undefined`, booleans, finite and non-finite numbers, and strings.
- [x] Array literals, including holes and spread from arrays, strings, Maps, Sets, URLSearchParams, custom synchronous
-      iterators, and synchronous generators.
+- [x] Array literals, including holes and spread from arrays, strings, Maps, Sets, URLSearchParams, Headers, custom
+      synchronous iterators, and synchronous generators.
 - [x] Object literals with shorthand, computed string/number keys, and spread following ToObject: data objects and
      arrays copy own enumerable keys, strings copy index keys, and other values contribute nothing.
 - [x] Template literals with interpolation.
@@ -56,7 +56,7 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 - [x] `NaN` and `Infinity` globals.
 - [ ] BigInt literals and in-interpreter BigInt arithmetic; BigInt remains invalid at JSON-like host boundaries.
 - [ ] Arbitrary Symbol primitive values and symbol-keyed properties. The confined `Symbol.iterator` and
-      `Symbol.asyncIterator` keys are available only for custom iterator protocols.
+      `Symbol.asyncIterator` keys are available only for the iterator protocols.
 - [ ] Tagged-template calls.
 - [ ] Getter and setter definitions in object literals.

@@ -95,9 +95,10 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 - [x] `if`/`else` and conditional expressions.
 - [x] `switch`, including default clauses and fallthrough.
 - [x] `for`, `while`, and `do...while`.
- [x] `for...of` over arrays, strings, Maps, Sets, URLSearchParams, custom synchronous iterators, and confined
-      synchronous generators. Abrupt completion invokes the iterator's optional `return()`.
- [x] `for...in` over own keys of plain objects, arrays, strings, and tool references; other values iterate nothing.
+- [x] `for...of` over arrays, strings, Maps, Sets, URLSearchParams, Headers, Uint8Arrays, built-in iterators, custom
+      synchronous iterators, and confined synchronous generators. Abrupt completion invokes the iterator's optional `return()`.
+- [x] `for...in` over own keys of plain objects, arrays, strings, and tool references. `null`, `undefined`, and other
+      non-objects iterate nothing. An un-awaited promise throws rather than iterating.
 - [x] Unlabeled `break` and `continue`.
 - [x] `try`, `catch`, optional catch bindings, and `finally`.
 - [x] `throw` with arbitrary values.
@@ -111,7 +112,8 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 ## Functions and callbacks

 - [x] Function declarations, function expressions, and arrow functions.
- [x] Synchronous and `async` functions.
+- [x] Synchronous and `async` functions. A line break between `function` and the name is allowed, as in JavaScript;
+      a line break between `async` and `function` is not an async function.
 - [x] Closures, recursion, default parameters, rest parameters, and destructured parameters.
 - [x] A call depth limit of 10000: deeper nesting throws a catchable `RangeError: Maximum call stack size exceeded`
      at the overflowing call instead of running until the timeout. Callbacks invoked by built-ins count below the
@@ -127,7 +129,7 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
      string). A detached method loses its receiver, as in JS: `values.filter("abc".includes)` is a `TypeError`
      because `includes` is called without a string `this`.
 - [x] Constructors work as callbacks with JS call semantics: `Error` types construct (`messages.map(Error)`),
-      and new-requiring constructors (`Map`, `Set`, `URL`, `URLSearchParams`, `Promise`) throw a `TypeError`,
+      and new-requiring constructors (`Map`, `Set`, `URL`, `URLSearchParams`, `Headers`, `Promise`) throw a `TypeError`,
      like JS.
 - [x] Tool references and detached `Promise` statics are rejected as callbacks with a hint to wrap them in an
      arrow function.
@@ -146,7 +148,6 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
      `Array.prototype.push.name === "push"`).
 - [ ] A named function expression's name is not bound inside its own body.
 - [ ] Redeclaring a function in the same scope is rejected; in JavaScript the last declaration wins.
- [ ] A line terminator between `async function` and the function name.
 - [ ] Generator and async generator functions evaluate parameter defaults and destructuring at the first `next()`
      rather than at the call, so their errors are not thrown synchronously.
 - [x] Synchronous and async generator declarations/expressions, `yield`, and `yield*`, including lazy bodies,
@@ -179,11 +180,12 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 - [x] Sequence expressions (the comma operator).
 - [x] `await` for CodeMode promises and callable thenables; a plain value passes through unchanged, though every
      `await` still defers its continuation one reaction turn.
- [x] `new` for Array, Object, Error types, Date, RegExp, Map, Set, URL, URLSearchParams, and Promise. `new` on any
-      other value throws a catchable `TypeError` naming the callee: other built-in functions such as `Number` say
-      `new` is unsupported and point at the plain call, user-defined functions report the constructor gap below, and
-      non-callable values are not constructors. Error constructors take the ES2022 options object, so
-      `new Error(message, { cause })` installs a non-enumerable `cause` when the option is present.
+- [x] `new` for Array, Object, Error types, Date, RegExp, Map, Set, URL, URLSearchParams, Headers, and Promise. `new`
+      on any other value throws a catchable `TypeError` naming the callee: other built-in functions such as `Number`
+      say `new` is unsupported and point at the plain call, user-defined functions report the constructor gap below,
+      and non-callable values are not constructors. Error constructors take the ES2022 options object, so
+      `new Error(message, { cause })` installs a non-enumerable `cause` when the option is present. `Error.isError`
+      is true for every Error value.
 - [x] Arithmetic operators: `+`, `-`, `*`, `/`, `%`, and `**`.
 - [x] Equality and ordering: `==`, `!=`, `===`, `!==`, `<`, `<=`, `>`, and `>=`.
 - [x] Bitwise operators: `&`, `|`, `^`, `~`, `<<`, `>>`, and `>>>`.
@@ -273,8 +275,9 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 - [x] `Object.is` for supported data values.
 - [x] `Object.groupBy` over finite collections and custom synchronous iterators/generators, with string-key coercion
      and plain-object results.
- [x] `Object.prototype` methods on values: `toString` (`"[object Array]"`), `toLocaleString`, `valueOf`,
-      `hasOwnProperty`, `isPrototypeOf`, and `propertyIsEnumerable`.
+- [x] `Object.prototype` methods on values: `toString` (`"[object Array]"`, `"[object Map]"`, `"[object Promise]"`, and so
+      on for every built-in kind, as JS reports through `Symbol.toStringTag`), `toLocaleString` (calls the value's
+      `toString`, as in JS), `valueOf`, `hasOwnProperty`, `isPrototypeOf`, and `propertyIsEnumerable`.

 ## Arrays

@@ -288,9 +291,14 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
      `lastIndexOf`.
 - [x] Aggregation: `reduce` and `reduceRight`.
 - [x] Ordering: `sort`, `toSorted`, `reverse`, and `toReversed`.
- [x] Access/copying: `at`, `slice`, `concat`, `flat`, `with`, and `join`.
+- [x] Access/copying: `at`, `slice`, `concat`, `flat`, `with`, `join`, and `toLocaleString` (each element's
+      `toLocaleString`, holes and nullish elements as empty strings).
 - [x] Mutation: `push`, `pop`, `shift`, `unshift`, `splice`, `fill`, and `copyWithin`.
- [x] Materialized iteration helpers: `keys`, `values`, and `entries` return arrays rather than iterators.
+- [x] `keys`, `values`, `entries`, and `[Symbol.iterator]` (the same function as `values`) return live iterator objects
+      with `next()` and `[Symbol.iterator]`, as in JS. Iterator objects are opaque references: they print as
+      `[opaque reference]`, serialize to `{}`, and cannot be passed to extensions. Every built-in collection iterator
+      shares one prototype. JavaScript gives each collection its own; the difference is not observable here because
+      `Object.getPrototypeOf` is not exposed.
 - [x] `length`, numeric indexing, index assignment, spread, and `for...of`.
 - [x] The `thisArg` argument of `Array.from` is accepted and ignored, like JS arrows.
 - [x] `Array.prototype.toSpliced`.
@@ -303,13 +311,13 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
      form, like `JSON.stringify`.
 - [ ] Argument coercion for `indexOf`, `lastIndexOf`, `includes`, `fill`, `flat`, `copyWithin`, and the `join`
      separator: JavaScript applies ToIntegerOrInfinity/ToString (including `valueOf`, strings, and `undefined`), the
-      interpreter requires numbers and strings; `includes()`/`indexOf()` with no argument should search for
-      `undefined`.
- [ ] Iterator objects from `keys`, `values`, and `entries` with a live `next()`.
+      interpreter requires numbers and strings. `indexOf()` and `lastIndexOf()` with no argument already search for
+      `undefined`; `includes()` still requires a value.

 ## Strings

- [x] Case/normalization: `toLowerCase`, `toUpperCase`, `normalize`.
+- [x] Case/normalization: `toLowerCase`, `toUpperCase`, `normalize`, and the `toLocaleLowerCase`/`toLocaleUpperCase`
+      aliases, which ignore their locale argument and apply the default Unicode casing.
 - [x] Trimming: `trim`, `trimStart`, and `trimEnd`, plus the Annex B `trimLeft` and `trimRight` aliases.
 - [x] Searching/tests: `includes`, `startsWith`, `endsWith`, `indexOf`, `lastIndexOf`, and `search`.
 - [x] Slicing/access: `slice`, `substring`, Annex B `substr`, `at`, `charAt`, `charCodeAt`, and `codePointAt`.
@@ -317,7 +325,7 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 - [x] Regular-expression integration: `match`, materialized `matchAll`, `replace`, `replaceAll`, `split`, and `search`.
 - [x] `localeCompare`; locale and options arguments are currently ignored.
 - [x] `isWellFormed` and `toWellFormed`.
- [x] `toString`, `length`, numeric indexing, spread, and `for...of` by Unicode code point.
+- [x] `toString`, `length`, numeric indexing, spread, `for...of`, and `[Symbol.iterator]` by Unicode code point.
 - [x] Static `String.fromCharCode` and `String.fromCodePoint`.
 - [x] Native argument coercion for supported String methods; for example, `includes(1)` and `slice("1")` coerce like
      native JS, `split(undefined)` returns the whole string, and `includes`/`startsWith`/`endsWith` reject regular
@@ -333,7 +341,8 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 - [x] Coercion functions: `Number`, `parseInt`, and `parseFloat`.
 - [x] Number predicates/parsers: `Number.isInteger`, `Number.isFinite`, `Number.isNaN`, `Number.isSafeInteger`,
      `Number.parseInt`, and `Number.parseFloat`.
- [x] Number formatting: `toFixed`, `toPrecision`, `toExponential`, `toString`, and `valueOf`.
+- [x] Number formatting: `toFixed`, `toPrecision`, `toExponential`, `toString`, `valueOf`, and `toLocaleString`, which
+      always formats as `en-US` (`"1,234.5"`) so output does not depend on the host.
 - [x] Number constants: `MAX_SAFE_INTEGER`, `MIN_SAFE_INTEGER`, `MAX_VALUE`, `MIN_VALUE`, `EPSILON`, `NaN`,
      `POSITIVE_INFINITY`, and `NEGATIVE_INFINITY`.
 - [x] Math constants: `PI`, `E`, `LN2`, `LN10`, `LOG2E`, `LOG10E`, `SQRT2`, and `SQRT1_2`.
@@ -346,7 +355,8 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
      use their epoch time) and reject opaque runtime references as data errors.
 - [x] Unknown static members on global namespaces and on `Number`/`String`/the coercion functions read as `undefined`
      for feature detection. Calling any undefined value reports a native-style `TypeError` naming the callee, for
-      example `Math.sum is not a function.` Unknown `Promise` statics keep their descriptive error.
+      example `Math.sum is not a function.` or `search(...).catch is not a function.` Unknown `Promise` statics keep
+      their descriptive error.
 - [x] `Math.sumPrecise` over finite collections and custom synchronous iterators/generators, rejecting non-number
      elements without coercion.
 - [x] Global coercing `isFinite` and `isNaN`; opaque runtime references reject as data errors, like `Number(...)`.
@@ -380,6 +390,8 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
      `TimeClip` behavior.
 - [x] `Date.prototype.toUTCString` and its `toGMTString` alias.
 - [x] `toDateString` and `toTimeString` in the host's local timezone.
+- [x] `toLocaleString`, `toLocaleDateString`, and `toLocaleTimeString` always format as `en-US` in UTC
+      (`"1/1/1970, 12:00:00 AM"`) so output does not depend on the host.
 - [x] Native one-argument Date coercion for supported values, including booleans, null, arrays, and plain objects.
 - [ ] Date setters and multi-argument construction coerce object arguments through `valueOf`/`toString` and surface
      their throws.
@@ -405,10 +417,11 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262

 - [x] Static `Map.groupBy` over finite collections and custom synchronous iterators/generators, preserving key identity.
 - [x] `new Map()` from synchronous iterables of entries.
- [x] Map `get`, `set`, `has`, `delete`, `clear`, `size`, and `forEach`.
+- [x] Map `get`, `set`, `has`, `delete`, `clear`, `size`, `forEach`, `getOrInsert`, and `getOrInsertComputed`.
 - [x] `new Set()` from synchronous iterables.
 - [x] Set `add`, `has`, `delete`, `clear`, `size`, and `forEach`.
- [x] Materialized `keys`, `values`, and `entries` arrays for Map and Set.
+- [x] Live `keys`, `values`, `entries`, and `[Symbol.iterator]` iterators for Map and Set; a Set-like operand's `keys()`
+      may return a built-in iterator or an array.
 - [x] Spread, `for...of`, `Array.from`, and `Object.fromEntries` integration.
 - [x] Map and Set values serialize to `{}` at host/JSON boundaries.
 - [x] Set composition and relation methods: `union`, `intersection`, `difference`, `symmetricDifference`, `isSubsetOf`,
@@ -424,8 +437,9 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 - [x] Writable URL fields except `origin`.
 - [x] `new URLSearchParams()` from query strings, data objects, synchronous iterables of pairs, and URLSearchParams.
 - [x] URLSearchParams `append`, `delete`, `get`, `getAll`, `has`, `set`, `sort`, `forEach`, `keys`, `values`,
-      `entries`, `toString`, and `size`.
- [x] URL values serialize to their href; URLSearchParams serialize to `{}`.
+      `entries`, `[Symbol.iterator]`, `toString`, and `size`.
+- [x] URL values are their href in `JSON.stringify` and at the host boundary. URLSearchParams are `{}` in
+      `JSON.stringify` and their query string at the host boundary.

 ## Uint8Array

@@ -437,7 +451,8 @@ with a hint to encode as text first (`TextDecoder`, `toBase64`, `toHex`).
 - [x] Index reads and writes with JS byte semantics: values wrap modulo 256, out-of-range writes are ignored, indexes
      cannot be deleted. `length` is a prototype accessor, so `Object.keys` lists only indexes.
 - [x] `at`, `slice`, `subarray` (a view on the same bytes), `set`, `fill`, `reverse`, `indexOf`, `lastIndexOf`,
-      `includes`, `join`, `toString`, `toBase64`, `toHex`, and materialized `keys`, `values`, and `entries` arrays.
+      `includes`, `join`, `toString`, `toBase64`, `toHex`, and live `keys`, `values`, `entries`, and `[Symbol.iterator]`
+      iterators.
 - [x] Spread, destructuring, `for...of`, `yield*`, `Array.from`, and `new Set(bytes)`. `Array.isArray` is false.
 - [x] String coercion joins with commas; `JSON.stringify` gives `{"0":1,...}`; `console.log` prints
      `Uint8Array(n) [...]`.
@@ -451,7 +466,13 @@ with a hint to encode as text first (`TextDecoder`, `toBase64`, `toHex`).
 - [x] `crypto.randomUUID()` and `crypto.getRandomValues(uint8Array)`.
 - [x] `TextEncoder` and `TextDecoder` for UTF-8 only: any other label is a `RangeError`. `TextDecoder` accepts the
      `fatal` and `ignoreBOM` options; `decode` takes a Uint8Array or nothing.
- [ ] `crypto.subtle`, `Blob`, and `TextDecoder` streaming or non-UTF-8 encodings.
+- [x] `new Headers()` from records, synchronous iterables of pairs, and Headers, wrapping the host's `Headers`: names
+      fold to lowercase, values are normalized and combined, and invalid names or values throw a `TypeError`.
+- [x] Headers `append`, `delete`, `get`, `getSetCookie`, `has`, `set`, `forEach`, `keys`, `values`, `entries`, and
+      `[Symbol.iterator]`; iteration is live and sorted by name, with `set-cookie` values kept apart.
+- [x] Headers serialize to a `{ name: value }` object in JSON, in results, and in tool arguments.
+- [ ] `Request`, `Response`, and `Blob`.
+- [ ] `crypto.subtle` and `TextDecoder` streaming or non-UTF-8 encodings.

 ## Extensions

@@ -461,9 +482,10 @@ Nothing is exposed unless a host provides it; extension calls are not tool calls
 - [x] Each global is a function, callable but not constructible, run with `this` undefined. A global that shadows
      a built-in or another extension throws at `make`.
 - [x] Every value crossing in either direction is converted, never shared: plain objects and arrays are copied,
-      `Date`, `RegExp`, `URL`, `URLSearchParams`, `Map`, `Set`, and `Uint8Array` become fresh copies with their
-      contents converted (a host `ArrayBuffer` comes in as a `Uint8Array`; other typed arrays cannot come out),
-      errors cross as errors with their name and message, and a `__proto__` key is dropped. Functions, generators,
+      `Date`, `RegExp`, `URL`, `URLSearchParams`, `Headers`, `Map`, `Set`, and `Uint8Array` become fresh copies with
+      their contents converted (a host `ArrayBuffer` comes in as a `Uint8Array`; other typed arrays cannot come out),
+      errors cross as errors with their name, message, `cause`, and own enumerable data, and a `__proto__` key is
+      dropped. Functions, generators,
      un-awaited promises, and symbols cannot be passed in; a class instance, a symbol, or a BigInt cannot come out.
 - [x] A host function inside a result becomes a program function whose calls cross the same way, so a result can
      carry methods (`res.json()`) whose host closures keep the host state. Diagnostics name it by its path
@@ -488,19 +510,21 @@ Nothing is exposed unless a host provides it; extension calls are not tool calls
 - [x] `AggregateError` with the `(errors, message?)` signature and an own `errors` array, constructed directly or by
      an all-rejected `Promise.any`; direct construction accepts custom synchronous iterators and generators.
 - [x] Error `name`/`message`, error inheritance through `instanceof`, and plain-data serialization. `message` is an own
-      non-enumerable property and `name` is inherited, as in JS, so `Object.keys(err)` is `[]` while the host still
-      receives `{ name, message }`. Errors have no `stack`; the diagnostic carries the source location instead.
+      non-enumerable property and `name` is inherited, as in JS, so `Object.keys(err)` is `[]` for a plain error. The
+      result boundary still emits `{ name, message, ...own enumerable }`, so a field such as `code` crosses. `cause` is
+      non-enumerable: an extension Error carries it, and this JSON form does not. Errors have no `stack`; the diagnostic
+      carries a 1-based line and column in the submitted source instead.
 - [x] `instanceof` against any constructor with a `prototype`, including every built-in and `Function`.
 - [x] Catchable user throws, runtime failures raised during interpreted evaluation, awaited tool failures, and awaited
      tool-call-limit failures; parse/compile failures, cooperative timeout, and output bounding remain outside program
      `catch`.
- [x] Source locations on unsupported-syntax diagnostics for JavaScript-shaped input; TypeScript transpilation may
-      shift them. The diagnostic names the rejected node type and attaches a short orientation to the supported
-      subset; this matrix is the full reference.
+- [x] Source locations on unsupported-syntax diagnostics. The diagnostic names the rejected node type and attaches a
+      short orientation to the supported subset; this matrix is the full reference.
 - [x] Model-visible host failure messages and underlying causes, including output-validation errors.
 - [x] Caught errors do not distinguish user throws, interpreter failures, and tool failures; a program sees one
-      Error-shaped value with `name` and `message` in `catch`, rejection handlers, and `Promise.allSettled` reasons.
-      This is deliberate: the program should handle a failure the same way regardless of where it originated.
+      Error-shaped value in `catch`, rejection handlers, and `Promise.allSettled` reasons. It always has `name` and
+      `message`, plus `cause` and own data when the failure carried them. This is deliberate: the program should
+      handle a failure the same way regardless of where it originated.
 - [x] Failures raised by the interpreter are `TypeError`s unless JavaScript names them otherwise (`RangeError`,
      `ReferenceError`, `SyntaxError`, `URIError`), so `e instanceof TypeError` and `e.constructor === TypeError`
      hold. Unsupported syntax reached at runtime is a `SyntaxError`; awaited tool failures stay plain `Error`.
@@ -1,7 +1,7 @@
 {
  "$schema": "https://json.schemastore.org/package.json",
  "name": "@opencode/codemode",
-  "version": "2.0.8",
+  "version": "2.0.11",
  "description": "Effect-native confined code execution over schema-described tools",
  "type": "module",
  "license": "MIT",
@@ -19,12 +19,6 @@
  "exports": {
    ".": "./src/index.ts"
  },
-  "imports": {
-    "#transpile": {
-      "workerd": "./src/interpreter/transpile.workerd.ts",
-      "default": "./src/interpreter/transpile.node.ts"
-    }
-  },
  "scripts": {
    "build": "bun run script/build.ts",
    "typecheck": "tsgo --noEmit",
@@ -32,8 +26,7 @@
  },
  "dependencies": {
    "acorn": "8.15.0",
-    "effect": "catalog:",
-    "typescript": "catalog:"
+    "effect": "catalog:"
  },
  "devDependencies": {
    "@tsconfig/bun": "catalog:",
@@ -15,7 +15,7 @@ const pkg = JSON.parse(originalText) as {
  name: string
  version: string
  exports: Record<string, string | { import: string; types: string }>
-  imports: Record<string, Record<string, string>>
+  imports?: Record<string, Record<string, string>>
 }
 const tarball = `${pkg.name.replace("@", "").replace("/", "-")}-${pkg.version}.tgz`
 const output = (value: string, types = false) =>
@@ -41,12 +41,14 @@ try {
      ]
    }),
  )
-  pkg.imports = Object.fromEntries(
-    Object.entries(pkg.imports).map(([key, conditions]) => [
-      key,
-      Object.fromEntries(Object.entries(conditions).map(([condition, value]) => [condition, output(value)])),
-    ]),
-  )
+  if (pkg.imports) {
+    pkg.imports = Object.fromEntries(
+      Object.entries(pkg.imports).map(([key, conditions]) => [
+        key,
+        Object.fromEntries(Object.entries(conditions).map(([condition, value]) => [condition, output(value)])),
+      ]),
+    )
+  }
  await Bun.write("package.json", JSON.stringify(pkg, null, 2) + "\n")
  await rm(tarball, { force: true })
  await $`bun pm pack`
@@ -15,21 +15,23 @@ import {
  Obj,
  PromiseObj,
  record,
+  type Value,
  SetObj,
  URLSearchParamsObj,
+  HeadersObj,
 } from "./interpreter/objects.js"
 import { typeofValue } from "./interpreter/references.js"

 export type Json = Schema.Json

-type Replacer<R> = (args: Array<unknown>) => Effect.Effect<unknown, unknown, R>
+type Replacer<R> = (args: Array<Value>) => Effect.Effect<Value, unknown, R>

 /**
 * What `JSON.stringify` would serialize for a program value, as host JSON: `toJSON` is honored, functions and
 * `undefined` vanish, non-finite numbers become null, and everything else is copied. Two departures from JS
 * so a mistake is not a silent `{}`: an Error serializes as `{ name, message, ...own }`, and a promise throws.
 */
-export const toJson = <R>(ctx: Interpreter<R>, value: unknown, replacer?: Replacer<R>) =>
+export const toJson = <R>(ctx: Interpreter<R>, value: Value, replacer?: Replacer<R>) =>
  walk(ctx, value, replacer, false)

 /**
@@ -37,11 +39,11 @@ export const toJson = <R>(ctx: Interpreter<R>, value: unknown, replacer?: Replac
 * awaited, a Set crosses as an array, a URLSearchParams as its query string, a Uint8Array asks to be encoded as
 * text first, and a `__proto__` key is dropped so host code can never receive one.
 */
-export const toBoundary = <R>(ctx: Interpreter<R>, value: unknown) => walk(ctx, value, undefined, true)
+export const toBoundary = <R>(ctx: Interpreter<R>, value: Value) => walk(ctx, value, undefined, true)

 const walk = <R>(
  ctx: Interpreter<R>,
-  value: unknown,
+  value: Value,
  replacer: Replacer<R> | undefined,
  boundary: boolean,
 ): Effect.Effect<Json | undefined, unknown, R> => {
@@ -69,6 +71,7 @@ const walk = <R>(
        )
      }
      if (boundary && value instanceof URLSearchParamsObj) return value.params.toString()
+      if (value instanceof HeadersObj) return Object.fromEntries(value.headers)
      const target = boundary && value instanceof SetObj ? new Arr(ctx.builtins.Array, [...value.set]) : value
      if (stack.has(target)) throw typeError("Converting circular structure to JSON.")
      stack.add(target)
@@ -102,7 +105,7 @@ const walk = <R>(
 }

 /** Host JSON as program values: objects and arrays are copied, primitives pass through. */
-export const fromJson = <R>(ctx: Interpreter<R>, value: unknown): unknown => {
+export const fromJson = <R>(ctx: Interpreter<R>, value: Json | undefined): Value => {
  if (value === null || typeof value !== "object") return value
  if (Array.isArray(value))
    return new Arr(
@@ -1,12 +1,12 @@
 import { Effect, Exit } from "effect"
-import { coerceToNumber, coerceToString } from "../stdlib/value.js"
 import type { Interpreter } from "./interpreter.js"
+import { primitivePrototype } from "./intrinsics.js"
 import { typeError } from "./model.js"
-import { Callable, get, Native, DateObj, Obj } from "./objects.js"
+import { Callable, get, Native, DateObj, Obj, coerceToNumber, coerceToString, type Value } from "./objects.js"
 import { typeofValue } from "./references.js"

 export type IteratorCursor<R> = {
-  readonly next: Effect.Effect<{ readonly done: boolean; readonly value: unknown }, unknown, R>
+  readonly next: Effect.Effect<{ readonly done: boolean; readonly value: Value }, unknown, R>
  readonly close: Effect.Effect<void, unknown, R>
 }

@@ -26,9 +26,9 @@ export const preserveConsumerError = <A, R>(
 */
 export const toPrimitive = <R>(
  ctx: Interpreter<R>,
-  value: unknown,
+  value: Value,
  hint: "number" | "string" | "default",
-): Effect.Effect<unknown, unknown, R> => {
+): Effect.Effect<Value, unknown, R> => {
  if (!(value instanceof Obj)) return Effect.succeed(value)
  const asString = hint === "string" || (hint === "default" && value instanceof DateObj)
  const order = asString ? ["toString", "valueOf"] : ["valueOf", "toString"]
@@ -43,24 +43,31 @@ export const toPrimitive = <R>(
  })
 }

-export const toPrimitiveString = <R>(ctx: Interpreter<R>, value: unknown) =>
+/** Invoke(value, name): calls the method the value would find through its prototype. */
+export const invoke = <R>(ctx: Interpreter<R>, value: Value, name: string, label: string) => {
+  const target = value instanceof Obj ? value : primitivePrototype(ctx.builtins, value)
+  if (target === undefined) throw typeError(`${label} called on null or undefined.`)
+  return ctx.call(get(target, name), value, [])
+}
+
+export const toPrimitiveString = <R>(ctx: Interpreter<R>, value: Value) =>
  Effect.map(toPrimitive(ctx, value, "string"), coerceToString)

-export const toPrimitiveNumber = <R>(ctx: Interpreter<R>, value: unknown) =>
+export const toPrimitiveNumber = <R>(ctx: Interpreter<R>, value: Value) =>
  Effect.map(toPrimitive(ctx, value, "number"), coerceToNumber)

 // The single acceptance list for callbacks: collections, sort, string replacers,
 // Array.from mappers, and promise reactions all admit exactly these callables.
 // Admission means dispatchable, not necessarily invocable: new-requiring
 // constructors pass the gate and throw a TypeError on call, like JS.
-export const isSupportedCallback = (value: unknown): value is Callable =>
+export const isSupportedCallback = (value: Value): value is Callable =>
  value instanceof Callable && !(value instanceof Native && !value.callback)

 export const applyCollectionCallback = <R>(
  ctx: Interpreter<R>,
-  callback: unknown,
+  callback: Value,
  name: string,
-): ((args: Array<unknown>) => Effect.Effect<unknown, unknown, R>) => {
+): ((args: Array<Value>) => Effect.Effect<Value, unknown, R>) => {
  if (!isSupportedCallback(callback)) {
    if (typeofValue(callback) === "function") {
      throw typeError(
@@ -6,10 +6,21 @@ import { type AstNode, formatLocation, PendingThrow, Throw, sourceLocation, type
 import { containsRuntimeReference } from "./references.js"
 import { createErrorValue, type ErrorType, isErrorType } from "./intrinsics.js"
 import { constructor, methods, prototypeFrom, receiver } from "./native.js"
-import { type Callable, define, get, has, hidden, type Native, Arr, ErrorObj, Obj } from "./objects.js"
+import {
+  type Callable,
+  define,
+  get,
+  has,
+  hidden,
+  type Native,
+  Arr,
+  ErrorObj,
+  Obj,
+  coerceToString,
+  type Value,
+} from "./objects.js"
 import type { Interpreter } from "./interpreter.js"
 import { formatValue } from "../stdlib/console.js"
-import { coerceToString } from "../stdlib/value.js"

 export const normalizeError = (error: unknown): Diagnostic => {
  if (error instanceof PendingThrow) {
@@ -86,7 +97,7 @@ export const locate = (error: unknown, node?: AstNode): unknown => {
 }

 /** The program value a handler receives for a failure; one failure always yields the same value. */
-export const materialize = <R>(ctx: Interpreter<R>, thrown: unknown): unknown => {
+export const materialize = <R>(ctx: Interpreter<R>, thrown: unknown): Value => {
  if (thrown instanceof Throw) return thrown.value
  const builtins = ctx.builtins
  if (thrown instanceof PendingThrow) {
@@ -113,7 +124,7 @@ const errorToString = (self: Obj): string => {

 export const createAggregateErrorValue = <R>(
  ctx: Interpreter<R>,
-  errors: Array<unknown>,
+  errors: Array<Value>,
  message: string,
  proto: Obj = ctx.builtins.AggregateError,
 ) => {
@@ -124,13 +135,13 @@ export const createAggregateErrorValue = <R>(

 const constructAggregateErrorValue = <R>(
  ctx: Interpreter<R>,
-  args: Array<unknown>,
+  args: Array<Value>,
  proto: Obj,
 ): Effect.Effect<ErrorObj, unknown, R> =>
  Effect.gen(function* () {
    const cursor = yield* ctx.iterate(args[0])
    if (cursor === undefined) throw typeError("new AggregateError(...) expects a synchronous iterable of errors.")
-    const errors: Array<unknown> = []
+    const errors: Array<Value> = []
    while (true) {
      const step = yield* cursor.next
      if (step.done) {
@@ -144,7 +155,7 @@ const constructAggregateErrorValue = <R>(
 export const errorGlobal = <R>(type: ErrorType, ctx: Interpreter<R>) => {
  const builtins = ctx.builtins
  const prototype = builtins[type]
-  const construct = (args: Array<unknown>, newTarget: Callable) => {
+  const construct = (args: Array<Value>, newTarget: Callable) => {
    const proto = prototypeFrom(newTarget, prototype)
    const created =
      type === "AggregateError"
@@ -168,6 +179,7 @@ export const errorGlobal = <R>(type: ErrorType, ctx: Interpreter<R>) => {
    methods(builtins, prototype, [
      ["toString", 0, (thisValue) => errorToString(receiver(Obj, thisValue, "Error.prototype.toString"))],
    ])
+    methods(builtins, ctor, [["isError", 1, (_, args) => args[0] instanceof ErrorObj]])
  }
  return ctor
 }
@@ -1,14 +1,11 @@
 import { parse, type Program } from "acorn"
 import { Cause, Effect, Scope } from "effect"
-// #transpile: conditional import — full typescript on node/bun, an identity
-// pass-through on workerd (the compiler is ~11 MiB and can't init there).
-import { transpile } from "#transpile"
 import type { DataValue, Diagnostic, ResolvedExecutionLimits, Result } from "../codemode.js"
 import { toBoundary } from "../data.js"
 import { ToolRuntime } from "../tool-runtime.js"
 import { normalizeError } from "./errors.js"
+import type { Value } from "./objects.js"
 import { createBuiltins } from "./intrinsics.js"
-import { PendingThrow } from "./model.js"
 import { Pending } from "./promises.js"
 import { Interpreter } from "./interpreter.js"

@@ -17,7 +14,7 @@ export const executeProgram = <R>(
  prepared: ToolRuntime.Prepared<R>,
  limits: ResolvedExecutionLimits,
  hooks: ToolRuntime.Hooks<R>,
-  globals?: (ctx: Interpreter<R>) => ReadonlyArray<readonly [string, unknown]>,
+  globals?: (ctx: Interpreter<R>) => ReadonlyArray<readonly [string, Value]>,
 ): Effect.Effect<Result, never, R> => {
  if (code.trim().length === 0) {
    return Effect.succeed({
@@ -110,16 +107,7 @@ export const executeProgram = <R>(
 }

 const parseProgram = (code: string): Program => {
-  const transpiled = transpile(`async function __codemode__() {\n${code}\n}`)
-
-  if (transpiled.error !== undefined) {
-    throw new PendingThrow("SyntaxError", `Failed to parse TypeScript: ${transpiled.error}`, undefined, "ParseError")
-  }
-
-  const bodyStart = transpiled.outputText.indexOf("{") + 1
-  const bodyEnd = transpiled.outputText.lastIndexOf("}")
-  const executableCode = transpiled.outputText.slice(bodyStart, bodyEnd)
-  return parse(executableCode, {
+  return parse(code, {
    ecmaVersion: "latest",
    sourceType: "script",
    allowReturnOutsideFunction: true,
@@ -1,6 +1,5 @@
 import { Effect } from "effect"
 import type { Extension } from "../extension.js"
-import { coerceToString } from "../stdlib/value.js"
 import { type ExtensionInvocation, hooked } from "../tool-runtime.js"
 import type { Interpreter } from "./interpreter.js"
 import { createErrorValue, isErrorType } from "./intrinsics.js"
@@ -8,9 +7,7 @@ import { MAX_VALUE_DEPTH } from "./limits.js"
 import { PendingThrow, Throw, typeError } from "./model.js"
 import { fn } from "./native.js"
 import {
-  Callable,
  define,
-  entries,
  get,
  has,
  hidden,
@@ -19,16 +16,17 @@ import {
  Bytes,
  DateObj,
  ErrorObj,
-  GeneratorObj,
+  HeadersObj,
  MapObj,
  Obj,
-  PromiseObj,
  RegExpObj,
  SetObj,
  URLObj,
  URLSearchParamsObj,
+  coerceToString,
+  type Value,
 } from "./objects.js"
-import { describeValue } from "./references.js"
+import { describeValue, isOpaque } from "./references.js"

 /**
 * The global bindings of one run's extensions. Everything crossing the boundary is converted: plain data and
@@ -38,33 +36,18 @@ import { describeValue } from "./references.js"
 export const extensionGlobals = <R>(
  ctx: Interpreter<R>,
  extensions: ReadonlyArray<Extension>,
-): ReadonlyArray<readonly [string, unknown]> => {
+): ReadonlyArray<readonly [string, Value]> => {
  const builtins = ctx.builtins

-  const toHost = (value: unknown, label: string, depth = 0, seen = new Set<object>()): unknown => {
+  const toHost = (value: Value, label: string, depth = 0, seen = new Set<object>()): unknown => {
    if (depth > MAX_VALUE_DEPTH) throw typeError(`${label} exceeds the maximum value depth of ${MAX_VALUE_DEPTH}.`)
-    if (value === null || typeof value !== "object") {
-      if (isPrimitive(value)) return value
-      throw typeError(`${label} contains ${describeValue(value)}, which cannot be passed to an extension.`)
-    }
-    if (value instanceof Bytes) return new Uint8Array(value.bytes)
-    if (value instanceof DateObj) return new Date(value.time)
-    if (value instanceof RegExpObj) return new RegExp(value.regex.source, value.regex.flags)
-    if (value instanceof URLObj) return new URL(value.url.href)
-    if (value instanceof URLSearchParamsObj) return new URLSearchParams(value.params)
-    const next = (item: unknown) => toHost(item, label, depth + 1, seen)
-    if (value instanceof MapObj) return new Map([...value.map].map(([key, item]) => [next(key), next(item)]))
-    if (value instanceof SetObj) return new Set([...value.set].map(next))
-    if (
-      !(value instanceof Obj) ||
-      value instanceof Callable ||
-      value instanceof GeneratorObj ||
-      value instanceof PromiseObj
-    ) {
+    if (isPrimitive(value)) return value
+    if (!(value instanceof Obj) || isOpaque(value)) {
      throw typeError(`${label} contains ${describeValue(value)}, which cannot be passed to an extension.`)
    }
    if (seen.has(value)) throw typeError(`${label} contains a circular value.`)
    seen.add(value)
+    const next = (item: Value) => toHost(item, label, depth + 1, seen)
    if (value instanceof ErrorObj) {
      const name = coerceToString(get(value, "name"))
      const message = get(value, "message")
@@ -85,19 +68,12 @@ export const extensionGlobals = <R>(
      seen.delete(value)
      return copied
    }
-    const copied =
-      value instanceof Arr
-        ? value.items.map(next)
-        : Object.fromEntries(
-            entries(value)
-              .filter(([key]) => key !== "__proto__")
-              .map(([key, item]) => [key, next(item)]),
-          )
+    const copied = value.toHost(next)
    seen.delete(value)
    return copied
  }

-  const fromHost = (value: unknown, label: string, depth = 0, seen = new Set<object>()): unknown => {
+  const fromHost = (value: unknown, label: string, depth = 0, seen = new Set<object>()): Value => {
    if (depth > MAX_VALUE_DEPTH) throw typeError(`${label} exceeds the maximum value depth of ${MAX_VALUE_DEPTH}.`)
    if (isPrimitive(value)) return value
    if (typeof value === "function") return wrap(value, label)
@@ -125,6 +101,7 @@ export const extensionGlobals = <R>(
      if (value instanceof URLSearchParams) {
        return new URLSearchParamsObj(builtins.URLSearchParams, new URLSearchParams(value))
      }
+      if (value instanceof Headers) return new HeadersObj(builtins.Headers, new Headers(value))
      if (value instanceof Map) {
        const wrapped = new MapObj(builtins.Map)
        for (const [key, item] of value) wrapped.map.set(next(key, label), next(item, label))
@@ -195,7 +172,7 @@ export const extensionGlobals = <R>(
 */
 const uncrossed = new Set(["stack", "constructor", "toString", "__proto__"])
 const left = Symbol("left behind")
-const crossing = (convert: () => unknown): unknown => {
+const crossing = <T>(convert: () => T): T | typeof left => {
  try {
    return convert()
  } catch (reason) {
@@ -214,7 +191,7 @@ const hostErrors = new Map<string, ErrorConstructor>([
 ])

 // The primitives the interpreter operates on; symbols and BigInts are not among them.
-const isPrimitive = (value: unknown): boolean =>
+const isPrimitive = (value: unknown): value is string | number | boolean | null | undefined =>
  value === null ||
  value === undefined ||
  typeof value === "string" ||
@@ -1,7 +1,7 @@
 import { Effect } from "effect"
 import { fn, type Method, methods, receiver } from "./native.js"
 import { AsyncIteratorSymbol, type GeneratorRequestKind, IteratorSymbol } from "./model.js"
-import { define, hidden, GeneratorObj } from "./objects.js"
+import { define, hidden, GeneratorObj, type Value } from "./objects.js"
 import type { Interpreter } from "./interpreter.js"

 /** `next`/`return`/`throw` on the generator prototypes; async generators answer with promises. */
@@ -13,9 +13,9 @@ export const generatorGlobals = <R>(ctx: Interpreter<R>): void => {
    const request = (kind: GeneratorRequestKind): Method => [
      kind,
      1,
-      (thisValue: unknown, args: Array<unknown>) => {
+      (thisValue: Value, args: Array<Value>) => {
        const generator = receiver(GeneratorObj, thisValue, `${label}.prototype.${kind}`)
-        const requested = generator.request(kind, args[0]) as Effect.Effect<unknown, unknown, R>
+        const requested = generator.request(kind, args[0]) as Effect.Effect<Value, unknown, R>
        return generator.asynchronous ? ctx.pending.create(requested) : requested
      },
    ]
@@ -1,4 +1,5 @@
 import { Effect } from "effect"
+import type { Value } from "./objects.js"
 import { arrayGlobal } from "../stdlib/array.js"
 import { textDecoderGlobal, textEncoderGlobal, uint8ArrayGlobal } from "../stdlib/bytes.js"
 import { mapGlobal, setGlobal } from "../stdlib/collections.js"
@@ -11,6 +12,8 @@ import { objectGlobal } from "../stdlib/object.js"
 import { regexpGlobal } from "../stdlib/regexp.js"
 import { stringGlobal } from "../stdlib/string.js"
 import { uriGlobal, urlGlobal, urlSearchParamsGlobal } from "../stdlib/url.js"
+import { headersGlobal } from "../stdlib/headers.js"
+import { iteratorGlobals } from "../stdlib/iterator.js"
 import { coercion } from "../stdlib/value.js"
 import { base64Global, cryptoGlobal } from "../stdlib/web.js"
 import { ToolReference } from "../tool-runtime.js"
@@ -49,7 +52,7 @@ const symbolGlobal = <R>(ctx: Interpreter<R>) => {
  return symbol
 }

-type Factory = <R>(ctx: Interpreter<R>) => unknown
+type Factory = <R>(ctx: Interpreter<R>) => Value

 // A table rather than a list so the names are known before any runtime exists.
 const table: Record<string, Factory> = {
@@ -80,6 +83,7 @@ const table: Record<string, Factory> = {
  Set: (ctx) => setGlobal(ctx),
  URL: (ctx) => urlGlobal(ctx),
  URLSearchParams: (ctx) => urlSearchParamsGlobal(ctx),
+  Headers: (ctx) => headersGlobal(ctx),
  Uint8Array: (ctx) => uint8ArrayGlobal(ctx),
  TextEncoder: (ctx) => textEncoderGlobal(ctx),
  TextDecoder: (ctx) => textDecoderGlobal(ctx),
@@ -97,7 +101,8 @@ const table: Record<string, Factory> = {
 export const globalNames: ReadonlySet<string> = new Set(Object.keys(table))

 /** The immutable global bindings of every program, in declaration order. */
-export const globals = <R>(ctx: Interpreter<R>): ReadonlyArray<readonly [string, unknown]> => {
+export const globals = <R>(ctx: Interpreter<R>): ReadonlyArray<readonly [string, Value]> => {
  generatorGlobals(ctx)
+  iteratorGlobals(ctx)
  return Object.entries(table).map(([name, factory]) => [name, factory(ctx)] as const)
 }
@@ -32,6 +32,7 @@ import type {
  Statement,
  Super,
  SwitchStatement,
+  Literal,
  TemplateLiteral,
  ThrowStatement,
  TryStatement,
@@ -62,7 +63,7 @@ import {
 } from "./model.js"
 import { checkStringLength } from "./limits.js"
 import { locate, materialize } from "./errors.js"
-import type { Builtins } from "./intrinsics.js"
+import { type Builtins, primitivePrototype } from "./intrinsics.js"
 import { globals } from "./globals.js"
 import {
  assign,
@@ -75,18 +76,16 @@ import {
  Native,
  parseArrayIndex,
  Arr,
-  Bytes,
-  DateObj,
  Fn,
  GeneratorObj,
-  MapObj,
  Obj,
  PromiseObj,
-  SetObj,
-  URLSearchParamsObj,
  record,
  remove,
  set,
+  coerceToNumber,
+  coerceToString,
+  type Value,
 } from "./objects.js"
 import { preserveConsumerError } from "./callback.js"
 import { Pending, resolvePromise, resolvePromiseValue } from "./promises.js"
@@ -94,7 +93,7 @@ import { containsOpaqueReference, describeValue, rejectCircularInsertion, typeof
 import { ScopeStack } from "./scope.js"
 import { constructRegExp } from "../stdlib/regexp.js"
 import { enumerableSource } from "../stdlib/object.js"
-import { coerceToNumber, coerceToString, compoundOperators } from "../stdlib/value.js"
+import { compoundOperators } from "../stdlib/value.js"

 // What a loop does with its body's result: exit with a StatementResult, or undefined to keep iterating.
 // Unlabelled break ends this loop; a label the loop does not carry propagates outward.
@@ -108,24 +107,36 @@ const loopExit = (result: StatementResult, labels: ReadonlySet<string> | undefin
  return undefined
 }

-const calleeDescription = (callee: Expression | Super | undefined): string => {
-  if (callee?.type === "Identifier") return callee.name
-  if (callee?.type === "MemberExpression") {
-    const object = callee.object
-    const property = callee.property
-    const key =
-      !callee.computed && property.type === "Identifier"
-        ? property.name
-        : property.type === "Literal" && typeof property.value === "string"
-          ? property.value
-          : undefined
-    if (object.type === "Identifier" && key !== undefined) return `${object.name}.${key}`
+// Native engines name the callee (`search(...).catch is not a function`), including call chains. Returns
+// undefined when a link cannot be named, so a chain is either named completely or not at all.
+const calleeDescription = (node: Expression | Super | undefined): string | undefined => {
+  if (node?.type === "Identifier") return node.name
+  if (node?.type === "CallExpression") {
+    const target = calleeDescription(node.callee)
+    return target === undefined ? undefined : `${target}(...)`
  }
-  return "The called value"
+  if (node?.type !== "MemberExpression") return undefined
+  const property = node.property
+  const key =
+    !node.computed && property.type === "Identifier"
+      ? property.name
+      : property.type === "Literal" && typeof property.value === "string"
+        ? property.value
+        : undefined
+  if (key === undefined) return undefined
+  const object = calleeDescription(node.object)
+  return object === undefined ? undefined : `${object}.${key}`
 }

 // OrdinaryHasInstance: walk the left operand's chain looking for the constructor's `prototype`.
-const instanceofValue = (lhs: unknown, rhs: unknown, node: AstNode): boolean => {
+// acorn types every literal as possibly a BigInt or RegExp; regex literals become RegExp objects before this is asked.
+const literal = (node: Literal): Value => {
+  if (typeof node.value === "bigint") throw typeError("BigInt literals are not supported.", node)
+  if (node.value instanceof RegExp) throw unsupportedSyntax("RegExpLiteral", node)
+  return node.value
+}
+
+const instanceofValue = (lhs: Value, rhs: Value, node: AstNode): boolean => {
  if (!(rhs instanceof Callable)) {
    throw typeError("The right-hand side of 'instanceof' is not callable.", node)
  }
@@ -222,7 +233,7 @@ const loopDeclaration = (left: VariableDeclaration | Pattern, statement: "for...

 type CustomIterator = {
  iterator: Obj
-  next: unknown
+  next: Value
  asynchronous: boolean
 }

@@ -230,13 +241,13 @@ type CustomIterator = {
 type MemberReference = {
  target: Obj
  key: PropertyKey
-  receiver: unknown
+  receiver: Value
 }

 type GeneratorRequest = {
  kind: GeneratorRequestKind
-  value: unknown
-  response: Deferred.Deferred<unknown, unknown>
+  value: Value
+  response: Deferred.Deferred<Value, unknown>
 }

 type GeneratorState = {
@@ -262,7 +273,7 @@ export class Interpreter<R> {
    readonly pending: Pending<R>
    readonly builtins: Builtins
    readonly logs?: Array<string>
-    readonly globals?: (ctx: Interpreter<R>) => ReadonlyArray<readonly [string, unknown]>
+    readonly globals?: (ctx: Interpreter<R>) => ReadonlyArray<readonly [string, Value]>
  }) {
    this.tools = options.tools
    this.pending = options.pending
@@ -276,27 +287,27 @@ export class Interpreter<R> {
    }
  }

-  run(program: Program): Effect.Effect<unknown, unknown, R> {
+  run(program: Program): Effect.Effect<Value, unknown, R> {
    return this.root.run(program)
  }

-  call(callable: unknown, thisValue: unknown, args: Array<unknown>): Effect.Effect<unknown, unknown, R> {
+  call(callable: Value, thisValue: Value, args: Array<Value>): Effect.Effect<Value, unknown, R> {
    return this.root.call(callable, thisValue, args)
  }

-  await(promise: PromiseObj): Effect.Effect<unknown, unknown, never> {
+  await(promise: PromiseObj): Effect.Effect<Value, unknown, never> {
    return this.root.await(promise)
  }

-  iterate(value: unknown) {
+  iterate(value: Value) {
    return this.root.iterate(value)
  }

  /** Runs one host tool: arguments cross as JSON and the result comes back as program values. */
  tool(
    run: (args: Array<Json | undefined>) => Effect.Effect<Json | undefined, unknown, R>,
-    args: Array<unknown>,
-  ): Effect.Effect<unknown, unknown, R> {
+    args: Array<Value>,
+  ): Effect.Effect<Value, unknown, R> {
    const ctx = this
    return Effect.gen(function* () {
      const json = yield* Effect.forEach(args, (arg) => toBoundary(ctx, arg))
@@ -319,7 +330,7 @@ class Frame<R> {
    private depth = 0,
  ) {}

-  run(program: Program): Effect.Effect<unknown, unknown, R> {
+  run(program: Program): Effect.Effect<Value, unknown, R> {
    const self = this
    // Keep top-level declarations separate so they can shadow builtins.
    this.scopes.push()
@@ -327,7 +338,7 @@ class Frame<R> {
      self.predeclareLexical(program.body)
      self.hoistFunctions(program.body)
      self.hoistVars(program.body)
-      let value: unknown = undefined
+      let value: Value = undefined
      for (const [index, statement] of program.body.entries()) {
        if (index === program.body.length - 1 && statement.type === "ExpressionStatement") {
          value = yield* self.evaluateExpression(statement.expression)
@@ -352,15 +363,12 @@ class Frame<R> {
  }

  // Fork at the call site so admission and hooks occur when the call is made.
-  private createToolCallPromise(
-    path: ReadonlyArray<string>,
-    args: Array<unknown>,
-  ): Effect.Effect<PromiseObj, never, R> {
+  private createToolCallPromise(path: ReadonlyArray<string>, args: Array<Value>): Effect.Effect<PromiseObj, never, R> {
    return this.ctx.pending.create(this.ctx.tool((json) => this.ctx.tools.execute(path, json), args))
  }

  // Fiber exits make settlement idempotent; yielding prevents inline continuation.
-  await(promise: PromiseObj): Effect.Effect<unknown, unknown, never> {
+  await(promise: PromiseObj): Effect.Effect<Value, unknown, never> {
    const pending = this.ctx.pending
    return Effect.suspend(() => {
      pending.markObserved(promise)
@@ -451,7 +459,7 @@ class Frame<R> {
  }

  // NamedEvaluation: an anonymous function definition takes the name of what it is assigned to.
-  private evaluateNamed(node: Expression, name: string): Effect.Effect<unknown, unknown, R> {
+  private evaluateNamed(node: Expression, name: string): Effect.Effect<Value, unknown, R> {
    if (node.type === "ArrowFunctionExpression" || (node.type === "FunctionExpression" && !node.id)) {
      return Effect.sync(() => this.createFunction(node, name))
    }
@@ -649,11 +657,11 @@ class Frame<R> {
      if (declared?.lexical) self.predeclarePattern(declared.pattern, declared.mutable, left)
      const right = yield* self.evaluateExpression(node.right)

-      const iterator = yield* self.customIterator(right, node, awaiting)
-      const cursor = iterator === undefined ? yield* self.iterate(right, node) : undefined
+      const cursor = self.hostCursor(right)
+      const iterator = cursor === undefined ? yield* self.customIterator(right, node, awaiting) : undefined
      if (iterator === undefined && cursor === undefined) {
        throw invalidData(
-          `${awaiting ? "for await...of" : "for...of"} requires an array, string, Map, Set, or URLSearchParams, or custom iterator value.`,
+          `${awaiting ? "for await...of" : "for...of"} requires an iterable value, received ${describeValue(right)}.`,
          node,
        )
      }
@@ -669,7 +677,7 @@ class Frame<R> {
      }
      const assignment = left.type === "VariableDeclaration" ? undefined : left

-      const evaluateBody = (value: unknown) =>
+      const evaluateBody = (value: Value) =>
        Effect.gen(function* () {
          if (declared?.lexical) {
            self.scopes.push()
@@ -718,7 +726,7 @@ class Frame<R> {
    )
  }

-  private awaitValue(value: unknown): Effect.Effect<unknown, unknown, R> {
+  private awaitValue(value: Value): Effect.Effect<Value, unknown, R> {
    return Effect.flatMap(resolvePromise(this.ctx, value), (promise) =>
      Effect.ensuring(
        this.await(promise),
@@ -729,10 +737,10 @@ class Frame<R> {

  private awaitAsyncFromSyncValue(
    iterator: CustomIterator,
-    value: unknown,
+    value: Value,
    node: AstNode | undefined,
    closeOnRejection: boolean,
-  ): Effect.Effect<unknown, unknown, R> {
+  ): Effect.Effect<Value, unknown, R> {
    const self = this
    return Effect.gen(function* () {
      const settled = yield* Effect.exit(self.awaitValue(value))
@@ -744,34 +752,9 @@ class Frame<R> {
    })
  }

-  iterate(value: unknown, node?: AstNode) {
-    const iterator =
-      value instanceof Arr
-        ? value.items[Symbol.iterator]()
-        : typeof value === "string"
-          ? value[Symbol.iterator]()
-          : value instanceof MapObj
-            ? value.map.entries()
-            : value instanceof SetObj
-              ? value.set.values()
-              : value instanceof URLSearchParamsObj
-                ? value.params.entries()
-                : value instanceof Bytes
-                  ? value.bytes.values()
-                  : undefined
-    if (iterator !== undefined) {
-      const proto = this.ctx.builtins.Array
-      return Effect.succeed({
-        next: Effect.sync(() => {
-          const step = iterator.next()
-          return {
-            done: Boolean(step.done),
-            value: Array.isArray(step.value) ? new Arr(proto, step.value) : step.value,
-          }
-        }),
-        close: Effect.void,
-      })
-    }
+  iterate(value: Value, node?: AstNode) {
+    const cursor = this.hostCursor(value)
+    if (cursor !== undefined) return Effect.succeed(cursor)
    const self = this
    return Effect.map(this.customIterator(value, node, false), (iterator) =>
      iterator === undefined
@@ -783,7 +766,24 @@ class Frame<R> {
    )
  }

-  private customIterator(value: unknown, node: AstNode | undefined, allowAsync = true) {
+  private hostCursor(value: Value) {
+    const iterator =
+      typeof value === "string"
+        ? value[Symbol.iterator]()
+        : value instanceof Obj
+          ? value.iterator(this.ctx.builtins)
+          : undefined
+    if (iterator === undefined) return undefined
+    return {
+      next: Effect.sync(() => {
+        const step = iterator.next()
+        return { done: Boolean(step.done), value: step.value }
+      }),
+      close: Effect.void,
+    }
+  }
+
+  private customIterator(value: Value, node: AstNode | undefined, allowAsync = true) {
    if (!(value instanceof Obj)) return Effect.undefined
    const asyncMethod = allowAsync ? get(value, AsyncIteratorSymbol) : undefined
    const method = asyncMethod ?? get(value, IteratorSymbol)
@@ -873,18 +873,18 @@ class Frame<R> {
    })
  }

-  private requireIteratorObject(value: unknown, context: string, node?: AstNode): Obj {
+  private requireIteratorObject(value: Value, context: string, node?: AstNode): Obj {
    if (value instanceof Obj) return value
    throw typeError(`${context} must be an object.`, node)
  }

-  private requireIteratorMethod(value: unknown, context: string, node?: AstNode): unknown {
+  private requireIteratorMethod(value: Value, context: string, node?: AstNode): Value {
    if (typeofValue(value) === "function") return value
    throw typeError(`${context} must be a function.`, node)
  }

  // for...in over null/undefined iterates nothing, like JS.
-  private enumerableKeys(value: unknown, node: AstNode): Array<string> {
+  private enumerableKeys(value: Value, node: AstNode): Array<string> {
    if (value instanceof ToolReference) return [...this.ctx.tools.keys(value.path)]
    if (value === null || value === undefined) return []
    return keys(enumerableSource(this.ctx, "for...in", value, node))
@@ -1048,7 +1048,7 @@ class Frame<R> {

  private declarePattern(
    pattern: Pattern,
-    value: unknown,
+    value: Value,
    mutable: boolean,
    node: AstNode,
    initialize = false,
@@ -1108,7 +1108,7 @@ class Frame<R> {
    })
  }

-  private assignPattern(pattern: Pattern, value: unknown, node: AstNode): Effect.Effect<void, unknown, R> {
+  private assignPattern(pattern: Pattern, value: Value, node: AstNode): Effect.Effect<void, unknown, R> {
    const self = this
    return Effect.gen(function* () {
      if (pattern.type === "Identifier") {
@@ -1160,7 +1160,7 @@ class Frame<R> {
    })
  }

-  private evaluateDefault(pattern: AssignmentPattern): Effect.Effect<unknown, unknown, R> {
+  private evaluateDefault(pattern: AssignmentPattern): Effect.Effect<Value, unknown, R> {
    return pattern.left.type === "Identifier"
      ? this.evaluateNamed(pattern.right, pattern.left.name)
      : this.evaluateExpression(pattern.right)
@@ -1168,8 +1168,8 @@ class Frame<R> {

  private destructureArrayPattern(
    pattern: ArrayPattern,
-    value: unknown,
-    consume: (target: Pattern, value: unknown, context: AstNode) => Effect.Effect<void, unknown, R>,
+    value: Value,
+    consume: (target: Pattern, value: Value, context: AstNode) => Effect.Effect<void, unknown, R>,
  ): Effect.Effect<void, unknown, R> {
    const self = this
    return Effect.gen(function* () {
@@ -1193,7 +1193,7 @@ class Frame<R> {
        done = step.done
        if (element === null) continue
        if (element.type === "RestElement") {
-          const rest: Array<unknown> = []
+          const rest: Array<Value> = []
          if (!step.done) rest.push(step.value)
          while (!done) {
            const next = yield* cursor.next
@@ -1223,13 +1223,12 @@ class Frame<R> {
    throw unsupportedSyntax(keyNode.type, keyNode)
  }

-  private evaluateExpression(node: Expression): Effect.Effect<unknown, unknown, R> {
+  private evaluateExpression(node: Expression): Effect.Effect<Value, unknown, R> {
    switch (node.type) {
      case "Literal": {
        const regex = node.regex
        if (regex) return Effect.sync(() => constructRegExp(this.ctx.builtins, [regex.pattern, regex.flags]))
-        if (typeof node.value === "bigint") throw typeError("BigInt literals are not supported.", node)
-        return Effect.succeed(node.value)
+        return Effect.succeed(literal(node))
      }
      case "Identifier":
        return Effect.sync(() => this.scopes.get(node.name, node))
@@ -1244,7 +1243,7 @@ class Frame<R> {
      case "SequenceExpression": {
        const self = this
        return Effect.gen(function* () {
-          let result: unknown
+          let result: Value
          for (const expression of node.expressions) {
            result = yield* self.evaluateExpression(expression)
          }
@@ -1285,7 +1284,7 @@ class Frame<R> {
    }
  }

-  private evaluateNewExpression(node: NewExpression): Effect.Effect<unknown, unknown, R> {
+  private evaluateNewExpression(node: NewExpression): Effect.Effect<Value, unknown, R> {
    const self = this
    return Effect.gen(function* () {
      const callee = yield* self.evaluateExpression(node.callee)
@@ -1295,7 +1294,7 @@ class Frame<R> {
        // `new` itself is supported, so a non-constructible callee is a TypeError like JS rather than
        // unsupported syntax. Built-ins like Number are real constructors in JS, so do not claim
        // otherwise; say `new` is unsupported for them and point at the plain call.
-        const name = calleeDescription(node.callee)
+        const name = calleeDescription(node.callee) ?? "The called value"
        const message =
          callee instanceof Fn
            ? `${name} cannot be constructed: user-defined constructors and classes are not supported. Call it as a function that returns a plain object instead.`
@@ -1309,7 +1308,7 @@ class Frame<R> {
    })
  }

-  private evaluateBinaryExpression(node: BinaryExpression): Effect.Effect<unknown, unknown, R> {
+  private evaluateBinaryExpression(node: BinaryExpression): Effect.Effect<Value, unknown, R> {
    const operator = node.operator
    const left = node.left
    if (left.type === "PrivateIdentifier") throw unsupportedSyntax(left.type, left)
@@ -1322,7 +1321,7 @@ class Frame<R> {
    })
  }

-  private applyBinaryOperator(operator: string, lhs: unknown, rhs: unknown, node: AstNode): unknown {
+  private applyBinaryOperator(operator: string, lhs: Value, rhs: Value, node: AstNode): Value {
    if (operator === "===") return lhs === rhs
    if (operator === "!==") return lhs !== rhs
    if (operator === "in" && rhs instanceof Obj && !containsOpaqueReference(lhs)) {
@@ -1331,14 +1330,9 @@ class Frame<R> {
    if (containsOpaqueReference(lhs) || containsOpaqueReference(rhs)) {
      throw invalidData("Binary operators require data values.", node)
    }
-    // Null-prototype data needs explicit primitive coercion; identity and `in` retain raw objects.
-    // Dates use their default string hint for addition and loose equality, and epoch time elsewhere.
-    const coerceOperand = (operand: unknown): unknown => {
-      if (operand instanceof DateObj) {
-        return operator === "+" || operator === "==" || operator === "!=" ? coerceToString(operand) : operand.time
-      }
-      return operand !== null && typeof operand === "object" ? coerceToString(operand) : operand
-    }
+    // Addition and loose equality use the default hint; every other operator asks for a number.
+    const hint = operator === "+" || operator === "==" || operator === "!=" ? "default" : "number"
+    const coerceOperand = (operand: Value) => (operand instanceof Obj ? operand.toPrimitive(hint) : operand)
    const bothObjects = lhs !== null && typeof lhs === "object" && rhs !== null && typeof rhs === "object"
    const l = coerceOperand(lhs)
    const r = coerceOperand(rhs)
@@ -1392,7 +1386,7 @@ class Frame<R> {
    }
  }

-  private evaluateLogicalExpression(node: LogicalExpression): Effect.Effect<unknown, unknown, R> {
+  private evaluateLogicalExpression(node: LogicalExpression): Effect.Effect<Value, unknown, R> {
    const operator = node.operator
    return Effect.flatMap(this.evaluateExpression(node.left), (left) => {
      if (operator === "&&") return left ? this.evaluateExpression(node.right) : Effect.succeed(left)
@@ -1403,7 +1397,7 @@ class Frame<R> {
    })
  }

-  private evaluateUnaryExpression(node: UnaryExpression): Effect.Effect<unknown, unknown, R> {
+  private evaluateUnaryExpression(node: UnaryExpression): Effect.Effect<Value, unknown, R> {
    const operator = node.operator
    const argument = node.argument
    if (operator === "delete") return this.evaluateDeleteExpression(argument)
@@ -1418,13 +1412,8 @@ class Frame<R> {
      if (containsOpaqueReference(value)) {
        throw invalidData("Unary operators require data values.", node)
      }
-      const operand =
-        value instanceof DateObj
-          ? value.time
-          : value !== null && typeof value === "object"
-            ? coerceToString(value)
-            : value
-      let result: unknown
+      const operand = value instanceof Obj ? value.toPrimitive("number") : value
+      let result: Value
      switch (operator) {
        case "+":
          result = +(operand as number)
@@ -1442,7 +1431,7 @@ class Frame<R> {
    })
  }

-  private evaluateAssignmentExpression(node: AssignmentExpression): Effect.Effect<unknown, unknown, R> {
+  private evaluateAssignmentExpression(node: AssignmentExpression): Effect.Effect<Value, unknown, R> {
    const left = node.left
    const operator = node.operator
    const self = this
@@ -1482,9 +1471,9 @@ class Frame<R> {
    node: AssignmentExpression,
    left: Pattern,
    operator: string,
-  ): Effect.Effect<unknown, unknown, R> {
+  ): Effect.Effect<Value, unknown, R> {
    const self = this
-    const shouldAssign = (current: unknown): boolean =>
+    const shouldAssign = (current: Value): boolean =>
      operator === "??=" ? current === null || current === undefined : operator === "||=" ? !current : Boolean(current)
    if (left.type === "Identifier") {
      const name = left.name
@@ -1509,7 +1498,7 @@ class Frame<R> {
    throw typeError("Assignment target must be an Identifier or MemberExpression.", left)
  }

-  private evaluateUpdateExpression(node: UpdateExpression): Effect.Effect<unknown, unknown, R> {
+  private evaluateUpdateExpression(node: UpdateExpression): Effect.Effect<Value, unknown, R> {
    const operator = node.operator
    const argument = node.argument
    const prefix = node.prefix
@@ -1522,7 +1511,7 @@ class Frame<R> {

    // CodeMode numeric coercion, not host Number(): null-prototype data objects would make
    // the host throw during ToPrimitive, and opaque runtime references must reject clearly.
-    const operand = (current: unknown): number => {
+    const operand = (current: Value): number => {
      if (containsOpaqueReference(current)) {
        throw invalidData(`'${operator}' requires a data value.`, argument)
      }
@@ -1551,7 +1540,7 @@ class Frame<R> {
  }

  // EvaluateCall: a member callee supplies its base object as `this`; anything else calls with undefined.
-  private evaluateCallExpression(node: CallExpression): Effect.Effect<unknown, unknown, R> {
+  private evaluateCallExpression(node: CallExpression): Effect.Effect<Value, unknown, R> {
    const callee = node.callee

    const self = this
@@ -1569,7 +1558,7 @@ class Frame<R> {
    })
  }

-  private readMethod(node: MemberExpression): Effect.Effect<{ callable: unknown; thisValue: unknown }, unknown, R> {
+  private readMethod(node: MemberExpression): Effect.Effect<{ callable: Value; thisValue: Value }, unknown, R> {
    return Effect.map(this.getMemberReference(node), (reference) => {
      if (reference === OptionalShortCircuit) return { callable: OptionalShortCircuit, thisValue: undefined }
      if (reference instanceof ToolReference) return { callable: reference, thisValue: undefined }
@@ -1580,12 +1569,12 @@ class Frame<R> {

  // The single dispatch for every invocation: call expressions and callbacks share it.
  call(
-    callable: unknown,
-    thisValue: unknown,
-    args: Array<unknown>,
+    callable: Value,
+    thisValue: Value,
+    args: Array<Value>,
    node?: AstNode,
    callee?: Expression,
-  ): Effect.Effect<unknown, unknown, R> {
+  ): Effect.Effect<Value, unknown, R> {
    const self = this
    return Effect.gen(function* () {
      if (callable instanceof ToolReference) {
@@ -1598,12 +1587,12 @@ class Frame<R> {
      if (callable instanceof Native) {
        return yield* self.native(() => (callable as Native<R>).call(thisValue, args), node)
      }
-      throw typeError(`${calleeDescription(callee)} is not a function.`, callee ?? node)
+      throw typeError(`${calleeDescription(callee) ?? "The called value"} is not a function.`, callee ?? node)
    })
  }

  // Built-ins throw without a location, synchronously or inside their Effect; the call site supplies it.
-  private native(body: () => Effect.Effect<unknown, unknown, R>, node?: AstNode): Effect.Effect<unknown, unknown, R> {
+  private native(body: () => Effect.Effect<Value, unknown, R>, node?: AstNode): Effect.Effect<Value, unknown, R> {
    return Effect.provideService(
      Effect.catchDefect(Effect.suspend(body), (defect) => Effect.die(locate(defect, node))),
      CallSite,
@@ -1613,10 +1602,10 @@ class Frame<R> {

  private evaluateCallArguments(
    argNodes: ReadonlyArray<Expression | SpreadElement>,
-  ): Effect.Effect<Array<unknown>, unknown, R> {
+  ): Effect.Effect<Array<Value>, unknown, R> {
    const self = this
    return Effect.gen(function* () {
-      const args: Array<unknown> = []
+      const args: Array<Value> = []
      for (const argNode of argNodes) {
        if (argNode.type === "SpreadElement") {
          const spread = yield* self.evaluateExpression(argNode.argument)
@@ -1636,7 +1625,7 @@ class Frame<R> {
  }

  // A callback invoked by a built-in runs below the call that invoked the built-in, so the deeper of the two counts.
-  invokeFunction(fn: Fn, args: Array<unknown>, node?: AstNode): Effect.Effect<unknown, unknown, R> {
+  invokeFunction(fn: Fn, args: Array<Value>, node?: AstNode): Effect.Effect<Value, unknown, R> {
    const self = this
    return Effect.flatMap(CallSite, (site) => {
      const depth = Math.max(self.depth, site.depth) + 1
@@ -1683,16 +1672,16 @@ class Frame<R> {

  private createGenerator(
    invocation: Frame<R>,
-    run: Effect.Effect<unknown, unknown, R>,
+    run: Effect.Effect<Value, unknown, R>,
    asynchronous: boolean,
  ): GeneratorObj {
    const state: GeneratorState = { started: false, completed: false, draining: false, pending: [], pendingIndex: 0 }
    invocation.generatorState = state
    invocation.generatorAsync = asynchronous
    const builtins = this.ctx.builtins
-    const result = (value: unknown, done: boolean) => record(builtins.Object, { value, done })
-    const request = (kind: GeneratorRequestKind, value: unknown) => {
-      const request = { kind, value, response: Deferred.makeUnsafe<unknown, unknown>() }
+    const result = (value: Value, done: boolean) => record(builtins.Object, { value, done })
+    const request = (kind: GeneratorRequestKind, value: Value) => {
+      const request = { kind, value, response: Deferred.makeUnsafe<Value, unknown>() }
      if (!asynchronous && state.active) return Effect.die(typeError("Generator is already running."))
      if (asynchronous && (state.completed || (!state.started && kind !== "next"))) {
        state.started = true
@@ -1763,7 +1752,7 @@ class Frame<R> {

  private completeGeneratorRequests(state: GeneratorState, asynchronous: boolean): Effect.Effect<void, never, R> {
    const self = this
-    const result = (value: unknown, done: boolean) => record(self.ctx.builtins.Object, { value, done })
+    const result = (value: Value, done: boolean) => record(self.ctx.builtins.Object, { value, done })
    return Effect.gen(function* () {
      while (true) {
        const pending = self.dequeueGeneratorRequest(state)
@@ -1809,7 +1798,7 @@ class Frame<R> {
    return request
  }

-  private evaluateYieldExpression(node: YieldExpression): Effect.Effect<unknown, unknown, R> {
+  private evaluateYieldExpression(node: YieldExpression): Effect.Effect<Value, unknown, R> {
    const argument = node.argument
    const self = this
    return Effect.gen(function* () {
@@ -1824,7 +1813,7 @@ class Frame<R> {
    })
  }

-  private suspendGenerator(value: unknown, node: AstNode): Effect.Effect<unknown, unknown, R> {
+  private suspendGenerator(value: Value, node: AstNode): Effect.Effect<Value, unknown, R> {
    const state = this.generatorState
    if (!state?.active) throw typeError("Generator has no active request.", node)
    Deferred.doneUnsafe(state.active.response, Exit.succeed(record(this.ctx.builtins.Object, { value, done: false })))
@@ -1839,19 +1828,11 @@ class Frame<R> {
    })
  }

-  private delegateYield(value: unknown, node: AstNode): Effect.Effect<unknown, unknown, R> {
+  private delegateYield(value: Value, node: AstNode): Effect.Effect<Value, unknown, R> {
    const self = this
    return Effect.gen(function* () {
-      if (
-        value instanceof Arr ||
-        typeof value === "string" ||
-        value instanceof MapObj ||
-        value instanceof SetObj ||
-        value instanceof URLSearchParamsObj ||
-        value instanceof Bytes
-      ) {
-        const cursor = yield* self.iterate(value, node)
-        if (!cursor) throw typeError("Built-in iterator is unavailable.", node)
+      const cursor = self.hostCursor(value)
+      if (cursor !== undefined) {
        while (true) {
          const step = yield* cursor.next
          if (step.done) return undefined
@@ -1875,7 +1856,7 @@ class Frame<R> {
      const iterator = yield* self.customIterator(value, node, self.generatorAsync)
      if (!iterator) throw typeError("yield* requires a compatible iterable value.", node)
      let kind: GeneratorRequestKind = "next"
-      let input: unknown = undefined
+      let input: Value = undefined
      while (true) {
        const method = kind === "next" ? iterator.next : get(iterator.iterator, kind)
        if (method === undefined || method === null) {
@@ -1895,7 +1876,7 @@ class Frame<R> {
          node,
        )
        const done = Boolean(get(result, "done"))
-        const resultValue: unknown =
+        const resultValue: Value =
          self.generatorAsync && !iterator.asynchronous
            ? yield* self.awaitAsyncFromSyncValue(iterator, get(result, "value"), node, kind !== "return" && !done)
            : get(result, "value")
@@ -1904,7 +1885,7 @@ class Frame<R> {
          return resultValue
        }

-        const resumed: Exit.Exit<unknown, unknown> = yield* Effect.exit(self.suspendGenerator(resultValue, node))
+        const resumed: Exit.Exit<Value, unknown> = yield* Effect.exit(self.suspendGenerator(resultValue, node))
        if (Exit.isSuccess(resumed)) {
          kind = "next"
          input = resumed.value
@@ -1945,7 +1926,7 @@ class Frame<R> {
        } else if (keyNode.type === "Identifier") {
          key = keyNode.name
        } else if (keyNode.type === "Literal") {
-          key = self.toPropertyKey(keyNode.value, keyNode)
+          key = self.toPropertyKey(literal(keyNode), keyNode)
        } else {
          throw typeError("Unsupported object property key shape.", keyNode)
        }
@@ -1964,7 +1945,7 @@ class Frame<R> {
  }

  private evaluateArrayExpression(node: ArrayExpression): Effect.Effect<Arr, unknown, R> {
-    const values: Array<unknown> = []
+    const values: Array<Value> = []

    const self = this
    return Effect.gen(function* () {
@@ -2019,13 +2000,13 @@ class Frame<R> {
    })
  }

-  private evaluateConditionalExpression(node: ConditionalExpression): Effect.Effect<unknown, unknown, R> {
+  private evaluateConditionalExpression(node: ConditionalExpression): Effect.Effect<Value, unknown, R> {
    return Effect.flatMap(this.evaluateExpression(node.test), (test) =>
      this.evaluateExpression(test ? node.consequent : node.alternate),
    )
  }

-  private applyCompoundAssignment(operator: string, current: unknown, incoming: unknown, node: AstNode): unknown {
+  private applyCompoundAssignment(operator: string, current: Value, incoming: Value, node: AstNode): Value {
    if (!compoundOperators.has(operator)) {
      throw typeError(`Unsupported assignment operator '${operator}'.`, node)
    }
@@ -2034,7 +2015,7 @@ class Frame<R> {

  private getMemberReference(
    node: MemberExpression,
-  ): Effect.Effect<MemberReference | ToolReference | { value: unknown } | typeof OptionalShortCircuit, unknown, R> {
+  ): Effect.Effect<MemberReference | ToolReference | { value: Value } | typeof OptionalShortCircuit, unknown, R> {
    const objectNode = node.object
    const propertyNode = node.property
    if (objectNode.type === "Super") throw unsupportedSyntax(objectNode.type, objectNode)
@@ -2060,16 +2041,14 @@ class Frame<R> {

      if (objectValue instanceof Obj) return { target: objectValue, key, receiver: objectValue }

-      // Primitives read through their wrapper prototype without being boxed; strings own length and indexes.
-      const builtins = self.ctx.builtins
+      // Strings own length and indexes; every other primitive property reads through the wrapper prototype.
      if (typeof objectValue === "string") {
        if (key === "length") return { value: objectValue.length }
        const index = typeof key === "symbol" ? undefined : parseArrayIndex(key)
        if (index !== undefined) return { value: objectValue[index] }
-        return { target: builtins.String, key, receiver: objectValue }
      }
-      if (typeof objectValue === "number") return { target: builtins.Number, key, receiver: objectValue }
-      if (typeof objectValue === "boolean") return { target: builtins.Boolean, key, receiver: objectValue }
+      const proto = primitivePrototype(self.ctx.builtins, objectValue)
+      if (proto !== undefined) return { target: proto, key, receiver: objectValue }

      if (objectValue === null || objectValue === undefined) {
        throw typeError(`Cannot read properties of ${objectValue} (reading '${String(key)}').`, objectNode)
@@ -2078,7 +2057,7 @@ class Frame<R> {
    })
  }

-  private readReference(reference: MemberReference, node: MemberExpression): unknown {
+  private readReference(reference: MemberReference, node: MemberExpression): Value {
    // Reject unknown promise properties so a missing await cannot hide.
    if (reference.target instanceof PromiseObj && !has(reference.target, reference.key)) {
      throw invalidData(
@@ -2090,7 +2069,7 @@ class Frame<R> {
  }

  // Accessors throw without a location; the member or pattern that read them supplies it.
-  private readProperty(target: Obj, key: PropertyKey, node: AstNode, receiver: unknown = target): unknown {
+  private readProperty(target: Obj, key: PropertyKey, node: AstNode, receiver: Value = target): Value {
    try {
      return get(target, key, receiver)
    } catch (error) {
@@ -2098,7 +2077,7 @@ class Frame<R> {
    }
  }

-  private readMember(node: MemberExpression): Effect.Effect<unknown, unknown, R> {
+  private readMember(node: MemberExpression): Effect.Effect<Value, unknown, R> {
    return Effect.map(this.getMemberReference(node), (reference) => {
      if (reference === OptionalShortCircuit) return OptionalShortCircuit
      if (reference instanceof ToolReference) return reference
@@ -2107,7 +2086,7 @@ class Frame<R> {
    })
  }

-  private writeMember(node: MemberExpression, value: unknown): Effect.Effect<unknown, unknown, R> {
+  private writeMember(node: MemberExpression, value: Value): Effect.Effect<Value, unknown, R> {
    return this.modifyMember(node, () => Effect.succeed({ write: true, next: value, result: value }))
  }

@@ -2129,8 +2108,8 @@ class Frame<R> {
  // Resolve side-effecting object and key expressions exactly once.
  private modifyMember(
    node: MemberExpression,
-    compute: (current: unknown) => Effect.Effect<{ write: boolean; next: unknown; result: unknown }, unknown, R>,
-  ): Effect.Effect<unknown, unknown, R> {
+    compute: (current: Value) => Effect.Effect<{ write: boolean; next: Value; result: Value }, unknown, R>,
+  ): Effect.Effect<Value, unknown, R> {
    const self = this
    return Effect.gen(function* () {
      const reference = yield* self.getMemberReference(node)
@@ -2150,7 +2129,7 @@ class Frame<R> {
    })
  }

-  private assignToReference(target: Obj, key: PropertyKey, next: unknown, node: AstNode): void {
+  private assignToReference(target: Obj, key: PropertyKey, next: Value, node: AstNode): void {
    const written = (() => {
      try {
        rejectCircularInsertion(
@@ -2168,7 +2147,7 @@ class Frame<R> {
    throw typeError(`Cannot assign to read only property '${String(key)}'.`, node)
  }

-  private toPropertyKey(value: unknown, node: AstNode): PropertyKey {
+  private toPropertyKey(value: Value, node: AstNode): PropertyKey {
    if (typeof value === "string" || typeof value === "number") {
      return value
    }
@@ -1,5 +1,5 @@
 import { Effect } from "effect"
-import { define, hidden, Native, Arr, ErrorObj, Obj } from "./objects.js"
+import { define, hidden, Native, Arr, ErrorObj, Obj, type Value } from "./objects.js"

 export const errorTypes = [
  "Error",
@@ -29,6 +29,7 @@ const builtins = [
  "Set",
  "URL",
  "URLSearchParams",
+  "Headers",
  "Uint8Array",
  "TextEncoder",
  "TextDecoder",
@@ -51,6 +52,14 @@ export const createErrorValue = (prototype: Obj, message: string | undefined): E
  return value
 }

+/** The prototype a primitive reads its methods from without being boxed; none for null, undefined, and symbols. */
+export const primitivePrototype = (builtins: Builtins, value: Value): Obj | undefined => {
+  if (typeof value === "string") return builtins.String
+  if (typeof value === "number") return builtins.Number
+  if (typeof value === "boolean") return builtins.Boolean
+  return undefined
+}
+
 export const createBuiltins = (): Builtins => {
  const object = new Obj(null)
  // Function.prototype is itself callable and returns undefined.
@@ -80,6 +89,7 @@ export const createBuiltins = (): Builtins => {
    Set: plain(),
    URL: plain(),
    URLSearchParams: plain(),
+    Headers: plain(),
    Uint8Array: plain(),
    TextEncoder: plain(),
    TextDecoder: plain(),
@@ -2,7 +2,7 @@ import type { Node } from "acorn"
 import { Context } from "effect"
 import type { ErrorType } from "./intrinsics.js"
 import type { DiagnosticKind } from "../codemode.js"
-import type { ErrorObj } from "./objects.js"
+import type { ErrorObj, Value } from "./objects.js"

 /** Any parsed node; the interpreter narrows on `type` and reads `loc` for diagnostics. */
 export type AstNode = Node
@@ -14,13 +14,13 @@ export const CallSite = Context.Reference<{ readonly node?: AstNode; readonly de

 export type Binding = {
  mutable: boolean
-  value: unknown
+  value: Value
  initialized?: boolean
 }

 export type StatementResult =
  | { kind: "none" }
-  | { kind: "return"; value: unknown }
+  | { kind: "return"; value: Value }
  | { kind: "break"; label?: string }
  | { kind: "continue"; label?: string }

@@ -31,11 +31,11 @@ export const IteratorSymbol: unique symbol = Symbol("codemode.iterator")
 export const IteratorSymbols = [AsyncIteratorSymbol, IteratorSymbol] as const

 export class Throw {
-  constructor(readonly value: unknown) {}
+  constructor(readonly value: Value) {}
 }

 export class GeneratorReturn {
-  constructor(readonly value: unknown) {}
+  constructor(readonly value: Value) {}
 }

 export const OptionalShortCircuit: unique symbol = Symbol("codemode.optional-short-circuit")
@@ -83,12 +83,10 @@ export const unsupportedSyntax = (kind: string, node: AstNode): PendingThrow =>
    [supportedSyntaxMessage],
  )

-export const isRecord = (value: unknown): value is Record<string, unknown> =>
-  typeof value === "object" && value !== null
-
+// Acorn lines are 1-based and its columns are 0-based. Diagnostics use 1-based columns of the submitted source.
 export const sourceLocation = (node: AstNode): { readonly line: number; readonly column: number } => ({
-  line: Math.max(1, (node.loc?.start.line ?? 2) - 1),
-  column: Math.max(1, (node.loc?.start.column ?? 4) - 3),
+  line: node.loc?.start.line ?? 1,
+  column: (node.loc?.start.column ?? 0) + 1,
 })

 export const formatLocation = (node?: AstNode): string => {
@@ -1,18 +1,18 @@
 import { Effect } from "effect"
 import type { Builtins } from "./intrinsics.js"
 import { typeError } from "./model.js"
-import { type Callable, define, frozen, hidden, Native, type NativeOptions, Obj } from "./objects.js"
+import { type Callable, define, frozen, hidden, Native, type NativeOptions, Obj, type Value } from "./objects.js"
 import { describeValue } from "./references.js"

-/** A native function body: a plain value, a thrown `PendingThrow`, or an Effect. */
-export type Impl = (thisValue: unknown, args: Array<unknown>) => unknown
+/** A native function body: a value, a thrown `PendingThrow`, or an Effect of a value. */
+export type Impl = (thisValue: Value, args: Array<Value>) => Value | Effect.Effect<Value, unknown, unknown>

 // The dispatch in `Frame.call` suspends every native call, so a synchronous throw here is a defect.
 const lift =
  <R>(impl: Impl) =>
-  (thisValue: unknown, args: Array<unknown>): Effect.Effect<unknown, unknown, R> => {
+  (thisValue: Value, args: Array<Value>): Effect.Effect<Value, unknown, R> => {
    const result = impl(thisValue, args)
-    return Effect.isEffect(result) ? (result as Effect.Effect<unknown, unknown, R>) : Effect.succeed(result)
+    return Effect.isEffect(result) ? (result as Effect.Effect<Value, unknown, R>) : Effect.succeed(result)
  }

 export const native = <R>(builtins: Builtins, options: NativeOptions<R>): Native<R> =>
@@ -27,7 +27,7 @@ export const methods = (builtins: Builtins, target: Obj, table: ReadonlyArray<Me
  for (const [name, length, impl] of table) define(target, name, fn(builtins, name, length, impl), hidden)
 }

-export const constants = (target: Obj, table: Record<string, unknown>): void => {
+export const constants = (target: Obj, table: Record<string, Value>): void => {
  for (const [name, value] of Object.entries(table)) define(target, name, value, frozen)
 }

@@ -54,7 +54,7 @@ export const prototypeFrom = (newTarget: Callable, fallback: Obj): Obj => {
 /** Narrows a method receiver to the built-in it belongs to, or throws the TypeError JS would. */
 export const receiver = <T extends Obj>(
  cls: abstract new (...args: never) => T,
-  thisValue: unknown,
+  thisValue: Value,
  method: string,
 ): T => {
  if (thisValue instanceof cls) return thisValue
@@ -1,5 +1,7 @@
 import type { BlockStatement, Expression, Pattern } from "acorn"
 import type { Effect, Fiber } from "effect"
+import { ToolReference } from "../tool-runtime.js"
+import type { Builtins } from "./intrinsics.js"
 import { checkArrayLength } from "./limits.js"
 import {
  AsyncIteratorSymbol,
@@ -16,12 +18,12 @@ export type Attributes = {
  readonly configurable: boolean
 }

-export type Getter = (receiver: unknown) => unknown
-export type Setter = (receiver: unknown, value: unknown) => void
+export type Getter = (receiver: Value) => Value
+export type Setter = (receiver: Value, value: Value) => void

 /** One own property: a data slot or a native accessor pair. */
 export type Slot =
-  | { value: unknown; writable: boolean; enumerable: boolean; configurable: boolean }
+  | { value: Value; writable: boolean; enumerable: boolean; configurable: boolean }
  | { get: Getter | undefined; set: Setter | undefined; enumerable: boolean; configurable: boolean }

 /** Ordinary assignment: writable, enumerable, configurable. */
@@ -33,33 +35,119 @@ export const readonly: Attributes = { writable: false, enumerable: false, config
 /** Constants such as `Math.PI` and a constructor's `prototype`. */
 export const frozen: Attributes = { writable: false, enumerable: false, configurable: false }

-/** An object owned by the program: own properties plus a prototype link. */
+/**
+ * An object owned by the program: own properties plus a prototype link. Subclasses answer, in one place, how a
+ * built-in kind of object prints, coerces, iterates, and crosses to the host.
+ */
 export class Obj {
  readonly props = new Map<string | symbol, Slot>()
  constructor(public proto: Obj | null) {}
+
+  /** The class name `Object.prototype.toString` reports: `[object Map]`. */
+  readonly tag: string = "Object"
+
+  /** How diagnostics refer to a value of this kind. */
+  get describe(): string {
+    if (this.tag === "Object") return "a data object"
+    return `${/^[AEIO]/.test(this.tag) ? "an" : "a"} ${this.tag}`
+  }
+
+  /** ToString without consulting program-defined methods. */
+  toString(): string {
+    return `[object ${this.tag}]`
+  }
+
+  /** ToPrimitive without consulting program-defined methods: only a Date answers a number hint differently. */
+  toPrimitive(hint: "default" | "number" | "string"): string | number {
+    return this.toString()
+  }
+
+  /** ToNumber without consulting program-defined methods. */
+  toNumber(): number {
+    return Number(this.toPrimitive("number"))
+  }
+
+  /** How `console.log` shows the value; `item` formats a child with cycle and depth tracking. */
+  inspect(item: (value: Value) => string): string {
+    return `{${entries(this)
+      .map(([key, value]) => `${JSON.stringify(key)}:${item(value)}`)
+      .join(",")}}`
+  }
+
+  /** A copy the host can hold; `item` converts a child. A `__proto__` key never reaches host code. */
+  toHost(item: (value: Value) => unknown): unknown {
+    return Object.fromEntries(
+      entries(this)
+        .filter(([key]) => key !== "__proto__")
+        .map(([key, value]) => [key, item(value)]),
+    )
+  }
+
+  /** The built-in iteration `for...of` and spread use, when this kind of object has one. */
+  iterator(builtins: Builtins): Iterator<Value, undefined> | undefined {
+    return undefined
+  }
 }

 export class Arr extends Obj {
+  override readonly tag = "Array"
  constructor(
    proto: Obj,
-    readonly items: Array<unknown> = [],
+    readonly items: Array<Value> = [],
  ) {
    super(proto)
  }
+  override get describe() {
+    return "an array"
+  }
+  override toString() {
+    return this.items.map((item) => (item === null || item === undefined ? "" : coerceToString(item))).join(",")
+  }
+  override inspect(item: (value: Value) => string) {
+    return `[${this.items.map(item).join(",")}]`
+  }
+  override toHost(item: (value: Value) => unknown) {
+    return this.items.map(item)
+  }
+  override iterator() {
+    return this.items.values()
+  }
 }

 /** An object with the [[ErrorData]] slot: what `Error.prototype.toString` and the host boundary recognize as an error. */
 export class ErrorObj extends Obj {
+  override readonly tag = "Error"
  /** The interpreter failure this error materialized from, so rethrowing it keeps the diagnostic kind and location. */
  host?: PendingThrow
+  /** Error.prototype.toString: "name: message", or just one when the other is empty. */
+  override toString() {
+    const name = get(this, "name")
+    const message = get(this, "message")
+    const shownName = typeof name === "string" ? name : "Error"
+    const shownMessage = typeof message === "string" ? message : ""
+    if (shownMessage === "") return shownName
+    if (shownName === "") return shownMessage
+    return `${shownName}: ${shownMessage}`
+  }
 }

-export abstract class Callable extends Obj {
+/** Interpreter machinery a program can hold but never inspect, serialize, or hand to the host. */
+export abstract class Opaque extends Obj {
+  override inspect() {
+    return "[opaque reference]"
+  }
+}
+
+export abstract class Callable extends Opaque {
+  override readonly tag = "Function"
  constructor(proto: Obj, name: string, length: number) {
    super(proto)
    define(this, "length", length, readonly)
    define(this, "name", name, readonly)
  }
+  override get describe() {
+    return "a function"
+  }
 }

 export class Fn extends Callable {
@@ -77,8 +165,8 @@ export class Fn extends Callable {
  }
 }

-export type NativeCall<R> = (thisValue: unknown, args: Array<unknown>) => Effect.Effect<unknown, unknown, R>
-export type NativeConstruct<R> = (args: Array<unknown>, newTarget: Callable) => Effect.Effect<unknown, unknown, R>
+export type NativeCall<R> = (thisValue: Value, args: Array<Value>) => Effect.Effect<Value, unknown, R>
+export type NativeConstruct<R> = (args: Array<Value>, newTarget: Callable) => Effect.Effect<Value, unknown, R>

 export type NativeOptions<R> = {
  readonly name: string
@@ -103,60 +191,163 @@ export class Native<R = never> extends Callable {
  }
 }

-export class PromiseObj extends Obj {
+export class PromiseObj extends Opaque {
+  override readonly tag = "Promise"
  constructor(
    proto: Obj,
-    readonly fiber: Fiber.Fiber<unknown, unknown>,
+    readonly fiber: Fiber.Fiber<Value, unknown>,
  ) {
    super(proto)
  }
+  override get describe() {
+    return "an un-awaited Promise"
+  }
+  override inspect() {
+    return "[Promise (await it to get its value)]"
+  }
 }

-export class GeneratorObj extends Obj {
+export class GeneratorObj extends Opaque {
+  override readonly tag = "Generator"
  constructor(
    proto: Obj,
    readonly asynchronous: boolean,
-    readonly request: (kind: GeneratorRequestKind, value: unknown) => Effect.Effect<unknown, unknown, unknown>,
+    readonly request: (kind: GeneratorRequestKind, value: Value) => Effect.Effect<Value, unknown, unknown>,
  ) {
    super(proto)
  }
+  override get describe() {
+    return "a generator"
+  }
 }

-export class DateObj extends Obj {
+/** A built-in collection iterator: live over the host collection, yielding program values. */
+export class IteratorObj extends Opaque {
+  override readonly tag = "Iterator"
+  constructor(
+    proto: Obj,
+    readonly source: IteratorObject<Value, undefined>,
+  ) {
+    super(proto)
+  }
+  override get describe() {
+    return "an iterator"
+  }
+  override iterator() {
+    return this.source
+  }
+}
+
+/** A built-in object around a host value: data-like, so it prints as itself and crosses to extensions as a copy. */
+export abstract class Wrapper extends Obj {
+  override inspect(item: (value: Value) => string) {
+    return this.toString()
+  }
+}
+
+export class DateObj extends Wrapper {
+  override readonly tag = "Date"
  constructor(
    proto: Obj,
    public time: number,
  ) {
    super(proto)
  }
+  override toString() {
+    return Number.isFinite(this.time) ? new Date(this.time).toISOString() : "Invalid Date"
+  }
+  override toPrimitive(hint: "default" | "number" | "string") {
+    return hint === "number" ? this.time : this.toString()
+  }
+  override toHost() {
+    return new Date(this.time)
+  }
 }

-export class RegExpObj extends Obj {
+export class RegExpObj extends Wrapper {
+  override readonly tag = "RegExp"
  readonly regex: RegExp
  constructor(proto: Obj, pattern: string, flags: string) {
    super(proto)
    this.regex = new RegExp(pattern, flags)
  }
+  override toString() {
+    return `/${this.regex.source}/${this.regex.flags}`
+  }
+  override toHost() {
+    return new RegExp(this.regex.source, this.regex.flags)
+  }
 }

-export class MapObj extends Obj {
-  readonly map = new Map<unknown, unknown>()
+export class MapObj extends Wrapper {
+  override readonly tag = "Map"
+  readonly map = new Map<Value, Value>()
+  override inspect(item: (value: Value) => string) {
+    return `Map(${this.map.size}) [${[...this.map].map(([key, value]) => `[${item(key)},${item(value)}]`).join(",")}]`
+  }
+  override toHost(item: (value: Value) => unknown) {
+    return new Map([...this.map].map(([key, value]) => [item(key), item(value)]))
+  }
+  override iterator(builtins: Builtins) {
+    return this.map.entries().map((entry) => new Arr(builtins.Array, entry))
+  }
 }

-export class SetObj extends Obj {
-  readonly set = new Set<unknown>()
+export class SetObj extends Wrapper {
+  override readonly tag = "Set"
+  readonly set = new Set<Value>()
+  override inspect(item: (value: Value) => string) {
+    return `Set(${this.set.size}) [${[...this.set].map(item).join(",")}]`
+  }
+  override toHost(item: (value: Value) => unknown) {
+    return new Set([...this.set].map(item))
+  }
+  override iterator() {
+    return this.set.values()
+  }
 }

-export class URLSearchParamsObj extends Obj {
+export class URLSearchParamsObj extends Wrapper {
+  override readonly tag = "URLSearchParams"
  constructor(
    proto: Obj,
    readonly params: URLSearchParams,
  ) {
    super(proto)
  }
+  override toString() {
+    return this.params.toString()
+  }
+  override toHost() {
+    return new URLSearchParams(this.params)
+  }
+  override iterator(builtins: Builtins) {
+    return this.params.entries().map((entry) => new Arr(builtins.Array, entry))
+  }
 }

-export class URLObj extends Obj {
+export class HeadersObj extends Wrapper {
+  override readonly tag = "Headers"
+  constructor(
+    proto: Obj,
+    readonly headers: Headers,
+  ) {
+    super(proto)
+  }
+  override inspect() {
+    return `Headers ${JSON.stringify(Object.fromEntries(this.headers))}`
+  }
+  override toHost() {
+    return new Headers(this.headers)
+  }
+  override iterator(builtins: Builtins) {
+    // Bun's Headers typings lack the iterator helpers, so the host iterator is lifted first.
+    return Iterator.from(this.headers.entries()).map((entry) => new Arr(builtins.Array, entry))
+  }
+}
+
+export class URLObj extends Wrapper {
+  override readonly tag = "URL"
  readonly searchParams: URLSearchParamsObj
  constructor(
    proto: Obj,
@@ -166,29 +357,52 @@ export class URLObj extends Obj {
    super(proto)
    this.searchParams = new URLSearchParamsObj(searchParamsProto, url.searchParams)
  }
+  override toString() {
+    return this.url.href
+  }
+  override toHost() {
+    return new URL(this.url.href)
+  }
 }

 /** A `Uint8Array`: the host array does the byte clamping and ignores out-of-range writes, as JS does. */
-export class Bytes extends Obj {
+export class Bytes extends Wrapper {
+  override readonly tag = "Uint8Array"
  constructor(
    proto: Obj,
    readonly bytes: Uint8Array,
  ) {
    super(proto)
  }
+  override toString() {
+    return this.bytes.join(",")
+  }
+  override inspect() {
+    return `Uint8Array(${this.bytes.length}) [${this.bytes.join(",")}]`
+  }
+  override toHost() {
+    return new Uint8Array(this.bytes)
+  }
+  override iterator() {
+    return this.bytes.values()
+  }
 }

-/** Built-in objects that wrap a host value; data-like, but never plain data. */
-export const isWrapper = (
-  value: unknown,
-): value is DateObj | RegExpObj | MapObj | SetObj | URLObj | URLSearchParamsObj | Bytes =>
-  value instanceof DateObj ||
-  value instanceof RegExpObj ||
-  value instanceof MapObj ||
-  value instanceof SetObj ||
-  value instanceof URLObj ||
-  value instanceof URLSearchParamsObj ||
-  value instanceof Bytes
+/** Every value a program can hold. Host values never appear here; they are copied in at the boundaries. */
+export type Value = string | number | boolean | null | undefined | symbol | Obj | ToolReference
+
+/** ToString without consulting program-defined methods. */
+export const coerceToString = (value: Value): string => (value instanceof Obj ? value.toString() : String(value))
+
+/** ToNumber without consulting program-defined methods; tool references are not numbers. */
+export const coerceToNumber = (value: Value): number => {
+  if (value instanceof Obj) return value.toNumber()
+  return value instanceof ToolReference ? Number.NaN : Number(value)
+}
+
+/** Values that cannot cross the data boundary: opaque machinery and host-backed wrappers. */
+export const isRuntimeReference = (value: Value): boolean =>
+  value instanceof Opaque || value instanceof Wrapper || value instanceof ToolReference

 const MAX_ARRAY_INDEX = 4_294_967_295

@@ -206,7 +420,7 @@ type Indexed = Arr | Bytes

 const isIndexed = (target: Obj): target is Indexed => target instanceof Arr || target instanceof Bytes

-const elements = (target: Indexed): Array<unknown> | Uint8Array => (target instanceof Arr ? target.items : target.bytes)
+const elements = (target: Indexed): Array<Value> | Uint8Array => (target instanceof Arr ? target.items : target.bytes)

 const index = (target: Obj, key: string | symbol): number | undefined =>
  isIndexed(target) && typeof key === "string" ? parseArrayIndex(key) : undefined
@@ -227,18 +441,18 @@ export const own = (target: Obj, key: PropertyKey): Slot | undefined => {
  return target.props.get(name)
 }

-const read = (slot: Slot, receiver: unknown): unknown =>
+const read = (slot: Slot, receiver: Value): Value =>
  "value" in slot ? slot.value : slot.get === undefined ? undefined : slot.get(receiver)

 export const hasOwn = (target: Obj, key: PropertyKey): boolean => own(target, key) !== undefined

-export const getOwn = (target: Obj, key: PropertyKey): unknown => {
+export const getOwn = (target: Obj, key: PropertyKey): Value => {
  const slot = own(target, key)
  return slot === undefined ? undefined : read(slot, target)
 }

 /** [[Get]]: walks the prototype chain; accessors see `receiver`, which is the primitive for wrapper prototypes. */
-export const get = (target: Obj, key: PropertyKey, receiver: unknown = target): unknown => {
+export const get = (target: Obj, key: PropertyKey, receiver: Value = target): Value => {
  for (let current: Obj | null = target; current !== null; current = current.proto) {
    const slot = own(current, key)
    if (slot !== undefined) return read(slot, receiver)
@@ -253,14 +467,14 @@ export const has = (target: Obj, key: PropertyKey): boolean => {
  return false
 }

-export const hasPrototype = (value: unknown, proto: Obj): boolean => {
+export const hasPrototype = (value: Value, proto: Obj): boolean => {
  for (let current = value instanceof Obj ? value.proto : null; current !== null; current = current.proto) {
    if (current === proto) return true
  }
  return false
 }

-const writeElement = (target: Indexed, name: string | symbol, value: unknown): boolean | undefined => {
+const writeElement = (target: Indexed, name: string | symbol, value: Value): boolean | undefined => {
  const at = index(target, name)
  if (at !== undefined) {
    if (target instanceof Bytes) target.bytes[at] = typeof value === "number" ? value : Number(value)
@@ -276,7 +490,7 @@ const writeElement = (target: Indexed, name: string | symbol, value: unknown): b
 }

 /** [[Set]]: an inherited setter or read-only property decides before an own data property is created. */
-export const set = (target: Obj, key: PropertyKey, value: unknown): boolean => {
+export const set = (target: Obj, key: PropertyKey, value: Value): boolean => {
  const name = canonical(key)
  for (let current: Obj | null = target; current !== null; current = current.proto) {
    const slot = own(current, name)
@@ -304,7 +518,7 @@ export const set = (target: Obj, key: PropertyKey, value: unknown): boolean => {
 }

 /** [[DefineOwnProperty]] for a data property, ignoring the chain. */
-export const define = (target: Obj, key: PropertyKey, value: unknown, attrs: Attributes = data): void => {
+export const define = (target: Obj, key: PropertyKey, value: Value, attrs: Attributes = data): void => {
  const name = canonical(key)
  if (isIndexed(target) && writeElement(target, name, value) !== undefined) return
  target.props.set(name, { value, ...attrs })
@@ -355,9 +569,9 @@ export const keys = (target: Obj): Array<string> =>
  ownKeys(target).filter((key): key is string => typeof key === "string" && enumerable(target, key))

 /** Own enumerable string entries: `Object.entries` and serialization. */
-export const entries = (target: Obj): Array<[string, unknown]> => keys(target).map((key) => [key, getOwn(target, key)])
+export const entries = (target: Obj): Array<[string, Value]> => keys(target).map((key) => [key, getOwn(target, key)])

-export const record = (proto: Obj, fields: Record<string, unknown>): Obj => {
+export const record = (proto: Obj, fields: Record<string, Value>): Obj => {
  const target = new Obj(proto)
  for (const [key, value] of Object.entries(fields)) define(target, key, value)
  return target
@@ -2,7 +2,7 @@ import { Cause, Deferred, Effect, Exit, Fiber, Scope } from "effect"
 import type { Diagnostic } from "../codemode.js"
 import { MAX_PENDING_PROMISES } from "./limits.js"
 import { CallSite, Throw, rangeError, typeError } from "./model.js"
-import { Callable, define, get, hidden, Arr, Fn, Obj, PromiseObj, record } from "./objects.js"
+import { Callable, define, get, hidden, Arr, Fn, Obj, PromiseObj, record, type Value } from "./objects.js"
 import { constructor, fn, methods, native, receiver, requiresNew } from "./native.js"
 import { createAggregateErrorValue, locate, materialize, normalizeError } from "./errors.js"
 import { typeofValue } from "./references.js"
@@ -10,7 +10,7 @@ import { applyCollectionCallback, isSupportedCallback } from "./callback.js"
 import type { Interpreter } from "./interpreter.js"

 // A `resolve`/`reject` handed to an executor or thenable: calling it settles the capability.
-const capability = <R>(ctx: Interpreter<R>, name: string, settle: (value: unknown) => void) =>
+const capability = <R>(ctx: Interpreter<R>, name: string, settle: (value: Value) => void) =>
  fn(ctx.builtins, name, 1, (_, args) => {
    settle(args[0])
    return undefined
@@ -31,7 +31,7 @@ export class Pending<R> {

  // Resolution bodies need the promise's own identity to reject `resolve(promise)` self-resolution.
  createWithSelf(
-    body: (self: { promise?: PromiseObj }) => Effect.Effect<unknown, unknown, R>,
+    body: (self: { promise?: PromiseObj }) => Effect.Effect<Value, unknown, R>,
  ): Effect.Effect<PromiseObj, never, R> {
    const self: { promise?: PromiseObj } = {}
    return Effect.map(this.create(body(self)), (promise) => {
@@ -40,7 +40,7 @@ export class Pending<R> {
    })
  }

-  create(effect: Effect.Effect<unknown, unknown, R>): Effect.Effect<PromiseObj, never, R> {
+  create(effect: Effect.Effect<Value, unknown, R>): Effect.Effect<PromiseObj, never, R> {
    return Effect.flatMap(CallSite, (site) => {
      if (this.active.size >= MAX_PENDING_PROMISES) {
        throw rangeError(
@@ -79,7 +79,7 @@ export class Pending<R> {
    if (id !== undefined) this.failures.delete(id)
  }

-  await(promise: PromiseObj): Effect.Effect<Exit.Exit<unknown, unknown>> {
+  await(promise: PromiseObj): Effect.Effect<Exit.Exit<Value, unknown>> {
    return Fiber.await(promise.fiber)
  }

@@ -105,9 +105,9 @@ export class Pending<R> {

 export const resolvePromiseValue = <R>(
  ctx: Interpreter<R>,
-  value: unknown,
+  value: Value,
  own?: { promise?: PromiseObj },
-): Effect.Effect<unknown, unknown, R> => {
+): Effect.Effect<Value, unknown, R> => {
  if (own?.promise !== undefined && value === own.promise) {
    return Effect.die(typeError("Chaining cycle detected: a promise cannot resolve with itself."))
  }
@@ -119,7 +119,7 @@ export const resolvePromiseValue = <R>(
  return Effect.gen(function* () {
    // Promise resolution invokes a thenable's method in a later job.
    yield* Effect.yieldNow
-    const deferred = Deferred.makeUnsafe<unknown, unknown>()
+    const deferred = Deferred.makeUnsafe<Value, unknown>()
    const resolve = capability(ctx, "resolve", (result) => Deferred.doneUnsafe(deferred, Exit.succeed(result)))
    const reject = capability(ctx, "reject", (reason) => Deferred.doneUnsafe(deferred, Exit.fail(new Throw(reason))))
    const executed = yield* Effect.exit(ctx.call(then, value, [resolve, reject]))
@@ -131,7 +131,7 @@ export const resolvePromiseValue = <R>(
  })
 }

-export const resolvePromise = <R>(ctx: Interpreter<R>, value: unknown): Effect.Effect<PromiseObj, never, R> => {
+export const resolvePromise = <R>(ctx: Interpreter<R>, value: Value): Effect.Effect<PromiseObj, never, R> => {
  if (value instanceof PromiseObj) return Effect.succeed(value)
  return ctx.pending.createWithSelf((self) => resolvePromiseValue(ctx, value, self))
 }
@@ -141,8 +141,8 @@ const promiseStatics = ["all", "allSettled", "race", "any", "resolve", "reject"]
 const invokePromiseMethod = <R>(
  ctx: Interpreter<R>,
  name: (typeof promiseStatics)[number],
-  args: Array<unknown>,
-): Effect.Effect<unknown, unknown, R> => {
+  args: Array<Value>,
+): Effect.Effect<Value, unknown, R> => {
  if (name === "resolve") {
    return resolvePromise(ctx, args[0])
  }
@@ -175,7 +175,7 @@ const invokePromiseMethod = <R>(
        )
      }
      if (name === "allSettled") {
-        const outcomes: Array<unknown> = []
+        const outcomes: Array<Value> = []
        for (const item of items) {
          const exit = yield* ctx.pending.await(item)
          if (Exit.isSuccess(exit)) {
@@ -223,8 +223,8 @@ const invokePromiseMethod = <R>(
 const instanceMethod = <R>(
  ctx: Interpreter<R>,
  name: "then" | "catch" | "finally",
-  thisValue: unknown,
-  args: Array<unknown>,
+  thisValue: Value,
+  args: Array<Value>,
 ): Effect.Effect<PromiseObj, unknown, R> => {
  const method = `Promise.prototype.${name}`
  const promise = receiver(PromiseObj, thisValue, method)
@@ -237,12 +237,12 @@ const instanceMethod = <R>(
  return chainReaction(ctx, promise, onFulfilled, onRejected, method)
 }

-const constructPromise = <R>(ctx: Interpreter<R>, executor: unknown): Effect.Effect<PromiseObj, unknown, R> => {
+const constructPromise = <R>(ctx: Interpreter<R>, executor: Value): Effect.Effect<PromiseObj, unknown, R> => {
  if (!(executor instanceof Fn)) {
    throw typeError("new Promise(...) expects an executor function (e.g. new Promise((resolve, reject) => { ... })).")
  }
  return Effect.gen(function* () {
-    const deferred = Deferred.makeUnsafe<unknown, unknown>()
+    const deferred = Deferred.makeUnsafe<Value, unknown>()
    const promise = yield* ctx.pending.createWithSelf((self) =>
      Effect.flatMap(Deferred.await(deferred), (value) => resolvePromiseValue(ctx, value, self)),
    )
@@ -262,10 +262,10 @@ const settleAfterTurn = <A, E, R>(body: Effect.Effect<A, E, R>): Effect.Effect<A
  Effect.flatMap(Effect.exit(body), (exit) => Effect.andThen(Effect.yieldNow, exit))

 class PromiseAnyFulfilled {
-  constructor(readonly value: unknown) {}
+  constructor(readonly value: Value) {}
 }

-const reactionHandler = (value: unknown, method: string): Callable | undefined => {
+const reactionHandler = (value: Value, method: string): Callable | undefined => {
  if (isSupportedCallback(value)) return value
  if (typeofValue(value) === "function") {
    throw typeError(
@@ -279,7 +279,7 @@ const reactionHandler = (value: unknown, method: string): Callable | undefined =
 const reactionExit = <R>(
  ctx: Interpreter<R>,
  source: PromiseObj,
-): Effect.Effect<Exit.Exit<unknown, unknown>, unknown, R> =>
+): Effect.Effect<Exit.Exit<Value, unknown>, unknown, R> =>
  Effect.gen(function* () {
    const exit = yield* ctx.pending.await(source)
    if (!Exit.isSuccess(exit) && Cause.hasInterruptsOnly(exit.cause)) return yield* Effect.failCause(exit.cause)
@@ -1,44 +1,18 @@
 import { ToolReference } from "../tool-runtime.js"
 import { invalidData } from "./model.js"
-import {
-  Callable,
-  getOwn,
-  isWrapper,
-  ownKeys,
-  Arr,
-  Bytes,
-  DateObj,
-  GeneratorObj,
-  MapObj,
-  Obj,
-  PromiseObj,
-  RegExpObj,
-  SetObj,
-  URLObj,
-  URLSearchParamsObj,
-} from "./objects.js"
+import { Callable, getOwn, isRuntimeReference, Obj, Opaque, ownKeys, type Value } from "./objects.js"

-/** Values that cannot cross the data boundary. */
-export const isRuntimeReference = (value: unknown): boolean =>
-  value instanceof Callable ||
-  value instanceof GeneratorObj ||
-  value instanceof ToolReference ||
-  value instanceof PromiseObj ||
-  isWrapper(value)
-
-function* childValues(value: object): Generator {
-  if (!(value instanceof Obj)) return
-  for (const key of ownKeys(value)) yield getOwn(value, key)
-}
+/** Interpreter machinery that is never data, unlike a Date or Map, which cross some boundaries as copies. */
+export const isOpaque = (value: Value): boolean => value instanceof Opaque || value instanceof ToolReference

 // Depth-first search over a value tree. `match` stops the walk; `skip` prunes a subtree without matching it.
 const find = (
-  value: unknown,
-  match: (current: unknown) => boolean,
-  skip: (current: unknown) => boolean,
+  value: Value,
+  match: (current: Value) => boolean,
+  skip: (current: Value) => boolean,
  seen: Set<object>,
 ): boolean => {
-  const pending: Array<Iterator<unknown>> = [[value].values()]
+  const pending: Array<Iterator<Value>> = [[value].values()]
  while (pending.length > 0) {
    const next = pending.at(-1)!.next()
    if (next.done) {
@@ -47,25 +21,28 @@ const find = (
    }
    const current = next.value
    if (match(current)) return true
-    if (current === null || typeof current !== "object" || skip(current) || seen.has(current)) continue
+    if (!(current instanceof Obj) || skip(current) || seen.has(current)) continue
    seen.add(current)
-    pending.push(childValues(current))
+    pending.push(
+      ownKeys(current)
+        .map((key) => getOwn(current, key))
+        .values(),
+    )
  }
  return false
 }

 const never = () => false

-export const containsRuntimeReference = (value: unknown): boolean => find(value, isRuntimeReference, never, new Set())
+export const containsRuntimeReference = (value: Value): boolean => find(value, isRuntimeReference, never, new Set())

-// Wrapper values are data here, not opaque interpreter references.
-export const containsOpaqueReference = (value: unknown): boolean =>
-  find(value, (current) => !isWrapper(current) && isRuntimeReference(current), isWrapper, new Set())
+export const containsOpaqueReference = (value: Value): boolean =>
+  find(value, isOpaque, (current) => isRuntimeReference(current) && !isOpaque(current), new Set())

 // Reject cycles before mutation so later boundary walks remain safe.
 export const rejectCircularInsertion = (
-  container: object,
-  value: unknown,
+  container: Obj,
+  value: Value,
  label: string,
  seen = new Set<object>(),
 ): void => {
@@ -74,25 +51,14 @@ export const rejectCircularInsertion = (
  }
 }

-export const describeValue = (value: unknown): string => {
+export const describeValue = (value: Value): string => {
  if (value === null || value === undefined) return String(value)
-  if (value instanceof Arr) return "an array"
-  if (value instanceof PromiseObj) return "an un-awaited Promise"
+  if (value instanceof Obj) return value.describe
  if (value instanceof ToolReference) return "a tool reference"
-  if (value instanceof DateObj) return "a Date"
-  if (value instanceof RegExpObj) return "a RegExp"
-  if (value instanceof MapObj) return "a Map"
-  if (value instanceof SetObj) return "a Set"
-  if (value instanceof URLObj) return "a URL"
-  if (value instanceof URLSearchParamsObj) return "a URLSearchParams"
-  if (value instanceof Bytes) return "a Uint8Array"
-  if (value instanceof GeneratorObj) return "a generator"
-  if (isRuntimeReference(value)) return "a function"
-  if (typeof value === "object") return "a data object"
  return `a ${typeof value}`
 }

-export const typeofValue = (value: unknown): string => {
+export const typeofValue = (value: Value): string => {
  if (value instanceof Callable) return "function"
  if (value instanceof ToolReference) return value.path.length > 0 ? "function" : "object"
  return typeof value
@@ -1,4 +1,5 @@
 import { type AstNode, type Binding, referenceError, typeError } from "./model.js"
+import type { Value } from "./objects.js"

 export class ScopeStack {
  private readonly scopes: Array<Map<string, Binding>>
@@ -15,7 +16,7 @@ export class ScopeStack {
    scope.set(name, { mutable, value: undefined, initialized: false })
  }

-  initialize(name: string, value: unknown, node: AstNode): void {
+  initialize(name: string, value: Value, node: AstNode): void {
    const binding = this.current().get(name)
    if (!binding || binding.initialized !== false) {
      throw typeError(`Identifier '${name}' has not been reserved for initialization.`, node)
@@ -24,7 +25,7 @@ export class ScopeStack {
    binding.initialized = true
  }

-  declare(name: string, value: unknown, mutable: boolean, node: AstNode): void {
+  declare(name: string, value: Value, mutable: boolean, node: AstNode): void {
    const scope = this.current()
    if (scope.has(name)) {
      throw typeError(`Identifier '${name}' has already been declared.`, node)
@@ -32,7 +33,7 @@ export class ScopeStack {
    scope.set(name, { mutable, value, initialized: true })
  }

-  get(name: string, node: AstNode): unknown {
+  get(name: string, node: AstNode): Value {
    const binding = this.resolve(name)

    if (!binding) {
@@ -46,7 +47,7 @@ export class ScopeStack {
    return binding.value
  }

-  set(name: string, value: unknown, node: AstNode): unknown {
+  set(name: string, value: Value, node: AstNode): Value {
    const binding = this.resolve(name)

    if (!binding) {
@@ -1,25 +0,0 @@
-import { DiagnosticCategory, ModuleKind, ScriptTarget, flattenDiagnosticMessageText, transpileModule } from "typescript"
-
-export interface TranspileResult {
-  readonly outputText: string
-  readonly error?: string
-}
-
-// Full TypeScript transpilation on node/bun runtimes.
-export const transpile = (source: string): TranspileResult => {
-  const transpiled = transpileModule(source, {
-    reportDiagnostics: true,
-    compilerOptions: {
-      target: ScriptTarget.ESNext,
-      module: ModuleKind.ESNext,
-    },
-  })
-  const diagnostic = transpiled.diagnostics?.find((item) => item.category === DiagnosticCategory.Error)
-  if (diagnostic) {
-    return {
-      outputText: transpiled.outputText,
-      error: flattenDiagnosticMessageText(diagnostic.messageText, "\n"),
-    }
-  }
-  return { outputText: transpiled.outputText }
-}
@@ -1,11 +0,0 @@
-export interface TranspileResult {
-  readonly outputText: string
-  readonly error?: string
-}
-
-// workerd profile: the typescript compiler is ~11 MiB and probes node
-// internals at module init, so codemode programs are passed through
-// untranspiled. Plain-JS programs (the overwhelmingly common case) parse
-// fine downstream via acorn; TypeScript-only syntax surfaces as a parse
-// error from the interpreter instead of a transpile diagnostic.
-export const transpile = (source: string): TranspileResult => ({ outputText: source })
@@ -1,15 +1,25 @@
 import { Effect } from "effect"
 import { constructor, type Method, methods, prototypeFrom, receiver } from "../interpreter/native.js"
 import { checkArrayLength, checkStringLength, MAX_ARRAY_LENGTH } from "../interpreter/limits.js"
-import { invalidData, rangeError, typeError } from "../interpreter/model.js"
-import { get, Arr, GeneratorObj, Obj } from "../interpreter/objects.js"
+import { invalidData, IteratorSymbol, rangeError, typeError } from "../interpreter/model.js"
+import {
+  define,
+  get,
+  hidden,
+  Arr,
+  GeneratorObj,
+  IteratorObj,
+  Obj,
+  coerceToNumber,
+  coerceToString,
+  type Value,
+} from "../interpreter/objects.js"
 import { describeValue, rejectCircularInsertion } from "../interpreter/references.js"
-import { applyCollectionCallback, preserveConsumerError } from "../interpreter/callback.js"
+import { applyCollectionCallback, invoke, preserveConsumerError } from "../interpreter/callback.js"
 import type { Interpreter } from "../interpreter/interpreter.js"
 import { compareText } from "../tool-runtime.js"
-import { coerceToNumber, coerceToString } from "./value.js"

-const arrayLikeSource = (source: unknown): { readonly length: number; readonly source: Obj } => {
+const arrayLikeSource = (source: Value): { readonly length: number; readonly source: Obj } => {
  if (source instanceof Obj && typeof get(source, "length") === "number") {
    const length = get(source, "length") as number
    const normalized = Number.isNaN(length) || length <= 0 ? 0 : Math.trunc(length)
@@ -21,7 +31,7 @@ const arrayLikeSource = (source: unknown): { readonly length: number; readonly s
  )
 }

-const arrayFrom = <R>(ctx: Interpreter<R>, args: Array<unknown>): Effect.Effect<unknown, unknown, R> => {
+const arrayFrom = <R>(ctx: Interpreter<R>, args: Array<Value>): Effect.Effect<Value, unknown, R> => {
  const source = args[0]
  const proto = ctx.builtins.Array
  const apply =
@@ -33,14 +43,14 @@ const arrayFrom = <R>(ctx: Interpreter<R>, args: Array<unknown>): Effect.Effect<
        throw typeError("Array.from expects a synchronous iterable or array-like value.")
      }
      const arrayLike = arrayLikeSource(source)
-      const values: Array<unknown> = []
+      const values: Array<Value> = []
      for (let index = 0; index < arrayLike.length; index += 1) {
        const item = get(arrayLike.source, index)
        values.push(apply === undefined ? item : yield* apply([item, index]))
      }
      return new Arr(proto, values)
    }
-    const values: Array<unknown> = []
+    const values: Array<Value> = []
    let index = 0
    while (true) {
      const step = yield* cursor.next
@@ -53,21 +63,21 @@ const arrayFrom = <R>(ctx: Interpreter<R>, args: Array<unknown>): Effect.Effect<

 export const sortArray = <R>(
  ctx: Interpreter<R>,
-  target: Array<unknown>,
-  comparator: unknown,
+  target: Array<Value>,
+  comparator: Value,
  name: string,
-): Effect.Effect<Array<unknown>, unknown, R> => {
+): Effect.Effect<Array<Value>, unknown, R> => {
  if (comparator === undefined) {
    return Effect.sync(() => [...target].sort((a, b) => compareText(coerceToString(a), coerceToString(b))))
  }
  const apply = applyCollectionCallback(ctx, comparator, name)
-  const mergeSort = (items: Array<unknown>): Effect.Effect<Array<unknown>, unknown, R> => {
+  const mergeSort = (items: Array<Value>): Effect.Effect<Array<Value>, unknown, R> => {
    if (items.length <= 1) return Effect.succeed(items)
    const midpoint = Math.floor(items.length / 2)
    return Effect.gen(function* () {
      const left = yield* mergeSort(items.slice(0, midpoint))
      const right = yield* mergeSort(items.slice(midpoint))
-      const merged: Array<unknown> = []
+      const merged: Array<Value> = []
      let leftIndex = 0
      let rightIndex = 0
      while (leftIndex < left.length && rightIndex < right.length) {
@@ -88,8 +98,8 @@ export const sortArray = <R>(
 export const arrayGlobal = <R>(ctx: Interpreter<R>) => {
  const builtins = ctx.builtins
  const proto = builtins.Array
-  const wrap = (items: Array<unknown>) => new Arr(proto, items)
-  const construct = (args: Array<unknown>, into: Obj): Arr => {
+  const wrap = (items: Array<Value>) => new Arr(proto, items)
+  const construct = (args: Array<Value>, into: Obj): Arr => {
    if (args.length !== 1) return new Arr(into, [...args])
    const first = args[0]
    if (typeof first !== "number") return new Arr(into, [first])
@@ -109,8 +119,8 @@ export const arrayGlobal = <R>(ctx: Interpreter<R>) => {
    ["from", 1, (_, args) => arrayFrom(ctx, args)],
  ])

-  const self = (thisValue: unknown, name: string) => receiver(Arr, thisValue, `Array.prototype.${name}`)
-  const optNumber = (name: string, value: unknown, label: string): number | undefined => {
+  const self = (thisValue: Value, name: string) => receiver(Arr, thisValue, `Array.prototype.${name}`)
+  const optNumber = (name: string, value: Value, label: string): number | undefined => {
    if (value === undefined) return undefined
    if (typeof value !== "number") {
      throw typeError(`Array.${name} expects ${label} to be a number.`)
@@ -122,11 +132,11 @@ export const arrayGlobal = <R>(ctx: Interpreter<R>) => {
    name: string,
    length: number,
    body: (
-      target: Array<unknown>,
+      target: Array<Value>,
      receiver: Arr,
-      apply: (args: Array<unknown>) => Effect.Effect<unknown, unknown, R>,
-      args: Array<unknown>,
-    ) => Effect.Effect<unknown, unknown, R>,
+      apply: (args: Array<Value>) => Effect.Effect<Value, unknown, R>,
+      args: Array<Value>,
+    ) => Effect.Effect<Value, unknown, R>,
  ): Method => [
    name,
    length,
@@ -214,7 +224,7 @@ export const arrayGlobal = <R>(ctx: Interpreter<R>) => {
      "flat",
      0,
      (thisValue, args) => {
-        const flatten = (items: Array<unknown>, depth: number): Array<unknown> =>
+        const flatten = (items: Array<Value>, depth: number): Array<Value> =>
          items.flatMap((item) => (item instanceof Arr && depth > 0 ? flatten(item.items, depth - 1) : [item]))
        const flattened = flatten(self(thisValue, "flat").items, optNumber("flat", args[0], "depth") ?? 1)
        checkArrayLength(flattened.length)
@@ -340,18 +350,36 @@ export const arrayGlobal = <R>(ctx: Interpreter<R>) => {
        return target
      },
    ],
-    ["keys", 0, (thisValue) => wrap(Array.from(self(thisValue, "keys").items.keys()))],
-    ["values", 0, (thisValue) => wrap([...self(thisValue, "values").items])],
+    [
+      "toLocaleString",
+      0,
+      (thisValue) =>
+        Effect.map(
+          Effect.forEach(self(thisValue, "toLocaleString").items, (item) =>
+            item === null || item === undefined
+              ? Effect.succeed("")
+              : Effect.map(invoke(ctx, item, "toLocaleString", "Array.prototype.toLocaleString"), coerceToString),
+          ),
+          (parts) => parts.join(","),
+        ),
+    ],
+    ["keys", 0, (thisValue) => new IteratorObj(builtins.Iterator, self(thisValue, "keys").items.keys())],
+    ["values", 0, (thisValue) => new IteratorObj(builtins.Iterator, self(thisValue, "values").items.values())],
    [
      "entries",
      0,
      (thisValue) =>
-        wrap(Array.from(self(thisValue, "entries").items.entries(), ([index, item]) => wrap([index, item]))),
+        new IteratorObj(
+          builtins.Iterator,
+          self(thisValue, "entries")
+            .items.entries()
+            .map(([index, item]) => wrap([index, item])),
+        ),
    ],
    iterate("map", 1, (target, receiver, apply) =>
      Effect.gen(function* () {
        const length = target.length
-        const values: Array<unknown> = []
+        const values: Array<Value> = []
        values.length = length
        for (let index = 0; index < length; index += 1) {
          if (!(index in target)) continue
@@ -363,7 +391,7 @@ export const arrayGlobal = <R>(ctx: Interpreter<R>) => {
    iterate("flatMap", 1, (target, receiver, apply) =>
      Effect.gen(function* () {
        const length = target.length
-        const values: Array<unknown> = []
+        const values: Array<Value> = []
        for (let index = 0; index < length; index += 1) {
          if (!(index in target)) continue
          const mapped = yield* apply([target[index], index, receiver])
@@ -376,7 +404,7 @@ export const arrayGlobal = <R>(ctx: Interpreter<R>) => {
    iterate("filter", 1, (target, receiver, apply) =>
      Effect.gen(function* () {
        const length = target.length
-        const values: Array<unknown> = []
+        const values: Array<Value> = []
        for (let index = 0; index < length; index += 1) {
          if (!(index in target)) continue
          const item = target[index]
@@ -490,5 +518,6 @@ export const arrayGlobal = <R>(ctx: Interpreter<R>) => {
      }),
    ),
  ])
+  define(proto, IteratorSymbol, get(proto, "values"), hidden)
  return array
 }
@@ -1,14 +1,25 @@
 import { Effect } from "effect"
 import { checkArrayLength, checkStringLength } from "../interpreter/limits.js"
 import { constructor, methods, prototypeFrom, receiver, requiresNew } from "../interpreter/native.js"
-import { rangeError, syntaxError, typeError } from "../interpreter/model.js"
-import { defineAccessor, get, Arr, Bytes, Obj } from "../interpreter/objects.js"
+import { IteratorSymbol, rangeError, syntaxError, typeError } from "../interpreter/model.js"
+import {
+  define,
+  defineAccessor,
+  get,
+  hidden,
+  Arr,
+  Bytes,
+  IteratorObj,
+  Obj,
+  coerceToNumber,
+  coerceToString,
+  type Value,
+} from "../interpreter/objects.js"
 import { describeValue } from "../interpreter/references.js"
 import type { Interpreter } from "../interpreter/interpreter.js"
-import { coerceToNumber, coerceToString } from "./value.js"

 /** The bytes a Uint8Array, array, or other iterable of numbers describes; the host array clamps each value. */
-const collectBytes = <R>(ctx: Interpreter<R>, source: unknown, name: string): Effect.Effect<Uint8Array, unknown, R> => {
+const collectBytes = <R>(ctx: Interpreter<R>, source: Value, name: string): Effect.Effect<Uint8Array, unknown, R> => {
  if (source instanceof Bytes) return Effect.succeed(new Uint8Array(source.bytes))
  return Effect.gen(function* () {
    const cursor = yield* ctx.iterate(source)
@@ -27,7 +38,7 @@ const collectBytes = <R>(ctx: Interpreter<R>, source: unknown, name: string): Ef
  })
 }

-const constructBytes = <R>(ctx: Interpreter<R>, args: Array<unknown>, proto: Obj) => {
+const constructBytes = <R>(ctx: Interpreter<R>, args: Array<Value>, proto: Obj) => {
  const source = args[0]
  if (source !== null && typeof source === "object") {
    return Effect.map(collectBytes(ctx, source, "new Uint8Array(...)"), (bytes) => new Bytes(proto, bytes))
@@ -48,7 +59,7 @@ export const uint8ArrayGlobal = <R>(ctx: Interpreter<R>) => {
    call: requiresNew("Uint8Array"),
    construct: (args, newTarget) => constructBytes(ctx, args, prototypeFrom(newTarget, proto)),
  })
-  const decode = (name: string, args: Array<unknown>, from: (text: string) => Uint8Array) => {
+  const decode = (name: string, args: Array<Value>, from: (text: string) => Uint8Array) => {
    if (typeof args[0] !== "string") throw typeError(`Uint8Array.${name} expects a string.`)
    try {
      return wrap(from(args[0]))
@@ -63,13 +74,13 @@ export const uint8ArrayGlobal = <R>(ctx: Interpreter<R>) => {
    ["fromHex", 1, (_, args) => decode("fromHex", args, (text) => Uint8Array.fromHex(text))],
  ])

-  const self = (thisValue: unknown, name: string) => receiver(Bytes, thisValue, `Uint8Array.prototype.${name}`)
-  const optNumber = (name: string, value: unknown, label: string): number | undefined => {
+  const self = (thisValue: Value, name: string) => receiver(Bytes, thisValue, `Uint8Array.prototype.${name}`)
+  const optNumber = (name: string, value: Value, label: string): number | undefined => {
    if (value === undefined) return undefined
    if (typeof value !== "number") throw typeError(`Uint8Array.${name} expects ${label} to be a number.`)
    return value
  }
-  const wrapAll = (items: Array<unknown>) => new Arr(builtins.Array, items)
+  const wrapAll = (items: Array<Value>) => new Arr(builtins.Array, items)
  defineAccessor(proto, "length", (thisValue) => self(thisValue, "length").bytes.length)
  methods(builtins, proto, [
    ["at", 1, (thisValue, args) => self(thisValue, "at").bytes.at(optNumber("at", args[0], "index") ?? 0)],
@@ -173,15 +184,21 @@ export const uint8ArrayGlobal = <R>(ctx: Interpreter<R>) => {
    ["toString", 0, (thisValue) => self(thisValue, "toString").bytes.join(",")],
    ["toBase64", 0, (thisValue) => self(thisValue, "toBase64").bytes.toBase64()],
    ["toHex", 0, (thisValue) => self(thisValue, "toHex").bytes.toHex()],
-    ["keys", 0, (thisValue) => wrapAll(Array.from(self(thisValue, "keys").bytes.keys()))],
-    ["values", 0, (thisValue) => wrapAll(Array.from(self(thisValue, "values").bytes.values()))],
+    ["keys", 0, (thisValue) => new IteratorObj(builtins.Iterator, self(thisValue, "keys").bytes.keys())],
+    ["values", 0, (thisValue) => new IteratorObj(builtins.Iterator, self(thisValue, "values").bytes.values())],
    [
      "entries",
      0,
      (thisValue) =>
-        wrapAll(Array.from(self(thisValue, "entries").bytes.entries(), ([index, byte]) => wrapAll([index, byte]))),
+        new IteratorObj(
+          builtins.Iterator,
+          self(thisValue, "entries")
+            .bytes.entries()
+            .map(([index, byte]) => wrapAll([index, byte])),
+        ),
    ],
  ])
+  define(proto, IteratorSymbol, get(proto, "values"), hidden)
  return uint8Array
 }

@@ -216,8 +233,7 @@ const utf8Labels = new Set(["unicode-1-1-utf-8", "unicode11utf8", "unicode20utf8
 export const textDecoderGlobal = <R>(ctx: Interpreter<R>) => {
  const builtins = ctx.builtins
  const proto = builtins.TextDecoder
-  const self = (thisValue: unknown, name: string) =>
-    receiver(TextDecoderObj, thisValue, `TextDecoder.prototype.${name}`)
+  const self = (thisValue: Value, name: string) => receiver(TextDecoderObj, thisValue, `TextDecoder.prototype.${name}`)
  defineAccessor(proto, "encoding", (thisValue) => self(thisValue, "encoding").decoder.encoding)
  defineAccessor(proto, "fatal", (thisValue) => self(thisValue, "fatal").decoder.fatal)
  defineAccessor(proto, "ignoreBOM", (thisValue) => self(thisValue, "ignoreBOM").decoder.ignoreBOM)
@@ -1,20 +1,22 @@
 import { Effect } from "effect"
 import { constructor, fn, type Method, methods, prototypeFrom, receiver, requiresNew } from "../interpreter/native.js"
-import { invalidData, typeError } from "../interpreter/model.js"
+import { invalidData, IteratorSymbol, typeError } from "../interpreter/model.js"
 import {
  define,
  defineAccessor,
  get,
  getOwn,
  hidden,
-  isWrapper,
  Arr,
+  coerceToString,
+  IteratorObj,
  MapObj,
  Obj,
  PromiseObj,
  SetObj,
+  type Value,
 } from "../interpreter/objects.js"
-import { describeValue, isRuntimeReference } from "../interpreter/references.js"
+import { describeValue, isOpaque } from "../interpreter/references.js"
 import {
  applyCollectionCallback,
  isSupportedCallback,
@@ -24,9 +26,9 @@ import {
 } from "../interpreter/callback.js"
 import type { Interpreter } from "../interpreter/interpreter.js"

-const coerceGroupByPropertyKey = <R>(ctx: Interpreter<R>, value: unknown): Effect.Effect<string, unknown, R> => {
-  if (value instanceof PromiseObj) return Effect.succeed("[object Promise]")
-  if (!isWrapper(value) && isRuntimeReference(value)) {
+const coerceGroupByPropertyKey = <R>(ctx: Interpreter<R>, value: Value): Effect.Effect<string, unknown, R> => {
+  if (value instanceof PromiseObj) return Effect.succeed(coerceToString(value))
+  if (isOpaque(value)) {
    throw invalidData(`Object.groupBy callback must return a data value, received ${describeValue(value)}.`)
  }
  return toPrimitiveString(ctx, value)
@@ -80,7 +82,7 @@ export const groupBy = <R>(ctx: Interpreter<R>, namespace: "Map" | "Object") =>
    })
  })

-const constructMap = <R>(ctx: Interpreter<R>, init: unknown, proto: Obj) => {
+const constructMap = <R>(ctx: Interpreter<R>, init: Value, proto: Obj) => {
  const target = new MapObj(proto)
  if (init === undefined || init === null) return Effect.succeed(target)
  return Effect.gen(function* () {
@@ -104,7 +106,7 @@ const constructMap = <R>(ctx: Interpreter<R>, init: unknown, proto: Obj) => {
  })
 }

-const constructSet = <R>(ctx: Interpreter<R>, init: unknown, proto: Obj) => {
+const constructSet = <R>(ctx: Interpreter<R>, init: Value, proto: Obj) => {
  const target = new SetObj(proto)
  if (init === undefined || init === null) return Effect.succeed(target)
  return Effect.gen(function* () {
@@ -129,8 +131,7 @@ export const mapGlobal = <R>(ctx: Interpreter<R>) => {
    construct: (args, newTarget) => constructMap(ctx, args[0], prototypeFrom(newTarget, proto)),
  })
  define(map, "groupBy", groupBy(ctx, "Map"), hidden)
-  const self = (thisValue: unknown, name: string) => receiver(MapObj, thisValue, `Map.prototype.${name}`)
-  const wrap = (items: Array<unknown>) => new Arr(builtins.Array, items)
+  const self = (thisValue: Value, name: string) => receiver(MapObj, thisValue, `Map.prototype.${name}`)
  defineAccessor(proto, "size", (thisValue) => receiver(MapObj, thisValue, "Map.prototype.size").map.size)
  methods(builtins, proto, [
    ["get", 1, (thisValue, args) => self(thisValue, "get").map.get(args[0])],
@@ -144,6 +145,29 @@ export const mapGlobal = <R>(ctx: Interpreter<R>) => {
        return target
      },
    ],
+    [
+      "getOrInsert",
+      2,
+      (thisValue, args) => {
+        const target = self(thisValue, "getOrInsert").map
+        if (!target.has(args[0])) target.set(args[0], args[1])
+        return target.get(args[0])
+      },
+    ],
+    [
+      "getOrInsertComputed",
+      2,
+      (thisValue, args) => {
+        const target = self(thisValue, "getOrInsertComputed").map
+        const apply = applyCollectionCallback(ctx, args[1], "Map.getOrInsertComputed")
+        if (target.has(args[0])) return target.get(args[0])
+        // The callback sees the stored key (-0 is +0) and its result wins over anything it inserted itself.
+        return Effect.map(apply([args[0] === 0 ? 0 : args[0]]), (value) => {
+          target.set(args[0], value)
+          return value
+        })
+      },
+    ],
    ["delete", 1, (thisValue, args) => self(thisValue, "delete").map.delete(args[0])],
    [
      "clear",
@@ -153,13 +177,9 @@ export const mapGlobal = <R>(ctx: Interpreter<R>) => {
        return undefined
      },
    ],
-    ["keys", 0, (thisValue) => wrap(Array.from(self(thisValue, "keys").map.keys()))],
-    ["values", 0, (thisValue) => wrap(Array.from(self(thisValue, "values").map.values()))],
-    [
-      "entries",
-      0,
-      (thisValue) => wrap(Array.from(self(thisValue, "entries").map.entries(), ([key, item]) => wrap([key, item]))),
-    ],
+    ["keys", 0, (thisValue) => new IteratorObj(builtins.Iterator, self(thisValue, "keys").map.keys())],
+    ["values", 0, (thisValue) => new IteratorObj(builtins.Iterator, self(thisValue, "values").map.values())],
+    ["entries", 0, (thisValue) => new IteratorObj(builtins.Iterator, self(thisValue, "entries").iterator(builtins))],
    [
      "forEach",
      1,
@@ -173,31 +193,32 @@ export const mapGlobal = <R>(ctx: Interpreter<R>) => {
      },
    ],
  ])
+  define(proto, IteratorSymbol, get(proto, "entries"), hidden)
  return map
 }

 type SetRecord<R> = {
  readonly size: number
-  readonly has: (item: unknown) => Effect.Effect<boolean, unknown, R>
-  readonly keys: () => Effect.Effect<Iterable<unknown>, unknown, R>
+  readonly has: (item: Value) => Effect.Effect<boolean, unknown, R>
+  readonly keys: () => Effect.Effect<Iterable<Value>, unknown, R>
 }

 const loadSetRecord = <R>(
  ctx: Interpreter<R>,
-  source: unknown,
+  source: Value,
  name: string,
 ): Effect.Effect<SetRecord<R>, unknown, R> => {
  if (source instanceof SetObj) {
    return Effect.succeed({
      size: source.set.size,
-      has: (item: unknown) => Effect.succeed(source.set.has(item)),
+      has: (item: Value) => Effect.succeed(source.set.has(item)),
      keys: () => Effect.succeed(source.set.values()),
    })
  }
  if (source instanceof MapObj) {
    return Effect.succeed({
      size: source.map.size,
-      has: (item: unknown) => Effect.succeed(source.map.has(item)),
+      has: (item: Value) => Effect.succeed(source.map.has(item)),
      keys: () => Effect.succeed(source.map.keys()),
    })
  }
@@ -216,9 +237,10 @@ const loadSetRecord = <R>(
    }
    return {
      size: Math.max(Math.trunc(size), 0),
-      has: (item: unknown) => Effect.map(ctx.call(has, source, [item]), Boolean),
+      has: (item: Value) => Effect.map(ctx.call(has, source, [item]), Boolean),
      keys: () =>
-        Effect.flatMap(ctx.call(keys, source, []), (result) => {
+        Effect.flatMap(ctx.call(keys, source, []), (result): Effect.Effect<Iterable<Value>> => {
+          if (result instanceof IteratorObj) return Effect.succeed(result.source)
          if (result instanceof Arr) return Effect.succeed(result.items)
          throw typeError(`Set.${name} expected 'keys' to return an iterator.`)
        }),
@@ -230,8 +252,8 @@ const setOperation = <R>(
  ctx: Interpreter<R>,
  target: SetObj,
  name: string,
-  source: unknown,
-): Effect.Effect<unknown, unknown, R> =>
+  source: Value,
+): Effect.Effect<Value, unknown, R> =>
  Effect.gen(function* () {
    const other = yield* loadSetRecord(ctx, source, name)
    const copy = () => {
@@ -310,8 +332,8 @@ export const setGlobal = <R>(ctx: Interpreter<R>) => {
    call: requiresNew("Set"),
    construct: (args, newTarget) => constructSet(ctx, args[0], prototypeFrom(newTarget, proto)),
  })
-  const self = (thisValue: unknown, name: string) => receiver(SetObj, thisValue, `Set.prototype.${name}`)
-  const wrap = (items: Array<unknown>) => new Arr(builtins.Array, items)
+  const self = (thisValue: Value, name: string) => receiver(SetObj, thisValue, `Set.prototype.${name}`)
+  const wrap = (items: Array<Value>) => new Arr(builtins.Array, items)
  const operation = (name: string): Method => [
    name,
    1,
@@ -338,12 +360,18 @@ export const setGlobal = <R>(ctx: Interpreter<R>) => {
        return undefined
      },
    ],
-    ["keys", 0, (thisValue) => wrap(Array.from(self(thisValue, "keys").set.values()))],
-    ["values", 0, (thisValue) => wrap(Array.from(self(thisValue, "values").set.values()))],
+    ["keys", 0, (thisValue) => new IteratorObj(builtins.Iterator, self(thisValue, "keys").set.values())],
+    ["values", 0, (thisValue) => new IteratorObj(builtins.Iterator, self(thisValue, "values").set.values())],
    [
      "entries",
      0,
-      (thisValue) => wrap(Array.from(self(thisValue, "entries").set.values(), (item) => wrap([item, item]))),
+      (thisValue) =>
+        new IteratorObj(
+          builtins.Iterator,
+          self(thisValue, "entries")
+            .set.values()
+            .map((item) => wrap([item, item])),
+        ),
    ],
    [
      "forEach",
@@ -365,5 +393,6 @@ export const setGlobal = <R>(ctx: Interpreter<R>) => {
    operation("isSupersetOf"),
    operation("isDisjointFrom"),
  ])
+  define(proto, IteratorSymbol, get(proto, "values"), hidden)
  return set
 }
@@ -1,21 +1,8 @@
 import { type Method, methods } from "../interpreter/native.js"
-import {
-  entries,
-  get,
-  Arr,
-  Bytes,
-  DateObj,
-  MapObj,
-  Obj,
-  PromiseObj,
-  RegExpObj,
-  SetObj,
-  URLObj,
-  URLSearchParamsObj,
-} from "../interpreter/objects.js"
-import { containsOpaqueReference, isRuntimeReference } from "../interpreter/references.js"
+import { entries, get, Arr, Obj, type Value } from "../interpreter/objects.js"
+import { ToolReference } from "../tool-runtime.js"
+import { containsOpaqueReference } from "../interpreter/references.js"
 import type { Interpreter } from "../interpreter/interpreter.js"
-import { coerceToString } from "./value.js"

 const consoleMethods = ["log", "info", "debug", "warn", "error", "dir", "table"]

@@ -42,7 +29,7 @@ export const consoleGlobal = <R>(ctx: Interpreter<R>) => {

 const MAX_CONSOLE_DEPTH = 32

-const formatConsoleMessage = (name: string, args: Array<unknown>): string => {
+const formatConsoleMessage = (name: string, args: Array<Value>): string => {
  if (name === "dir") return args.length === 0 ? "undefined" : formatValue(args[0])
  if (name === "table") return formatConsoleTable(args[0], args[1])
  const prefix = name === "warn" ? "[warn] " : name === "error" ? "[error] " : name === "debug" ? "[debug] " : ""
@@ -50,59 +37,27 @@ const formatConsoleMessage = (name: string, args: Array<unknown>): string => {
 }

 /** One value as `console.log` shows it. */
-export const formatValue = (value: unknown): string => {
+export const formatValue = (value: Value): string => {
  if (value === undefined) return "undefined"
  if (typeof value === "string") return value
  return formatConsoleValue(value, new Set(), 0)
 }

-const formatConsoleValue = (value: unknown, seen: Set<object>, depth: number): string => {
+const formatConsoleValue = (value: Value, seen: Set<object>, depth: number): string => {
  if (value === null || value === undefined) return "null"
  if (typeof value === "string") return JSON.stringify(value)
-  if (typeof value === "number" || typeof value === "boolean") return String(value)
-  if (typeof value !== "object") return String(value)
-  if (value instanceof PromiseObj) return "[Promise (await it to get its value)]"
-  if (value instanceof DateObj) return coerceToString(value)
-  if (value instanceof RegExpObj) return coerceToString(value)
-  if (value instanceof URLObj) return coerceToString(value)
-  if (value instanceof URLSearchParamsObj) return coerceToString(value)
-  if (value instanceof Bytes) return `Uint8Array(${value.bytes.length}) [${value.bytes.join(",")}]`
+  if (!(value instanceof Obj)) return value instanceof ToolReference ? "[opaque reference]" : String(value)
  if (depth > MAX_CONSOLE_DEPTH) return "..."
  if (seen.has(value)) return "[Circular]"
-  if (value instanceof MapObj) {
-    seen.add(value)
-    try {
-      const items = Array.from(value.map.entries(), ([key, item]) => `[${formatItems([key, item], seen, depth + 1)}]`)
-      return `Map(${value.map.size}) [${items.join(",")}]`
-    } finally {
-      seen.delete(value)
-    }
-  }
-  if (value instanceof SetObj) {
-    seen.add(value)
-    try {
-      return `Set(${value.set.size}) [${formatItems([...value.set.values()], seen, depth + 1)}]`
-    } finally {
-      seen.delete(value)
-    }
-  }
-  if (isRuntimeReference(value)) return "[opaque reference]"
  seen.add(value)
  try {
-    if (value instanceof Arr) return `[${formatItems(value.items, seen, depth + 1)}]`
-    if (!(value instanceof Obj)) return "[object Object]"
-    return `{${entries(value)
-      .map(([key, item]) => `${JSON.stringify(key)}:${formatConsoleValue(item, seen, depth + 1)}`)
-      .join(",")}}`
+    return value.inspect((item) => formatConsoleValue(item, seen, depth + 1))
  } finally {
    seen.delete(value)
  }
 }

-const formatItems = (items: Array<unknown>, seen: Set<object>, depth: number): string =>
-  items.map((item) => formatConsoleValue(item, seen, depth)).join(",")
-
-const formatConsoleTable = (value: unknown, columnsArgument: unknown): string => {
+const formatConsoleTable = (value: Value, columnsArgument: Value): string => {
  if (value === undefined) return "undefined"
  if (containsOpaqueReference(value)) return "[opaque reference]"
  const columns = columnsArgument instanceof Arr ? columnsArgument.items.map(String) : undefined
@@ -116,9 +71,9 @@ const formatConsoleTable = (value: unknown, columnsArgument: unknown): string =>
 }

 const consoleTableRows = (
-  data: unknown,
+  data: Value,
  columns: ReadonlyArray<string> | undefined,
-): Array<{ readonly index: string; readonly values: Record<string, unknown> }> => {
+): Array<{ readonly index: string; readonly values: Record<string, Value> }> => {
  if (data instanceof Arr) {
    return data.items.map((item, index) => ({ index: String(index), values: consoleTableValues(item, columns) }))
  }
@@ -128,7 +83,7 @@ const consoleTableRows = (
  return [{ index: "0", values: { Value: data } }]
 }

-const consoleTableValues = (value: unknown, columns: ReadonlyArray<string> | undefined): Record<string, unknown> => {
+const consoleTableValues = (value: Value, columns: ReadonlyArray<string> | undefined): Record<string, Value> => {
  if (value instanceof Obj && !(value instanceof Arr)) {
    if (columns !== undefined) return Object.fromEntries(columns.map((column) => [column, get(value, column)]))
    return Object.fromEntries(entries(value))
@@ -136,7 +91,7 @@ const consoleTableValues = (value: unknown, columns: ReadonlyArray<string> | und
  return { Value: value }
 }

-const formatConsoleTableCell = (value: unknown): string => {
+const formatConsoleTableCell = (value: Value): string => {
  if (value === undefined) return ""
  if (typeof value === "string") return value
  return formatConsoleValue(value, new Set(), 0)
@@ -1,12 +1,11 @@
 import { Effect } from "effect"
 import { constructor, type Method, methods, prototypeFrom, receiver } from "../interpreter/native.js"
 import { rangeError } from "../interpreter/model.js"
-import { DateObj, Obj } from "../interpreter/objects.js"
+import { DateObj, Obj, coerceToNumber, coerceToString, type Value } from "../interpreter/objects.js"
 import { toPrimitive, toPrimitiveNumber } from "../interpreter/callback.js"
 import type { Interpreter } from "../interpreter/interpreter.js"
-import { coerceToNumber, coerceToString } from "./value.js"

-const constructDate = <R>(ctx: Interpreter<R>, args: Array<unknown>, proto: Obj) => {
+const constructDate = <R>(ctx: Interpreter<R>, args: Array<Value>, proto: Obj) => {
  if (args.length === 0) return Effect.succeed(new DateObj(proto, Date.now()))
  if (args.length === 1) {
    const arg = args[0]
@@ -83,7 +82,7 @@ export const dateGlobal = <R>(ctx: Interpreter<R>) => {
    ["UTC", 7, (_, args) => Date.UTC(...(args.map((arg) => coerceToNumber(arg)) as Parameters<typeof Date.UTC>))],
  ])

-  const self = (thisValue: unknown, name: string) => receiver(DateObj, thisValue, `Date.prototype.${name}`)
+  const self = (thisValue: Value, name: string) => receiver(DateObj, thisValue, `Date.prototype.${name}`)
  const iso = (value: DateObj) => {
    if (!Number.isFinite(value.time)) throw rangeError("Invalid time value.")
    return new Date(value.time).toISOString()
@@ -105,6 +104,13 @@ export const dateGlobal = <R>(ctx: Interpreter<R>) => {
    ["toTimeString", 0, (thisValue) => new Date(self(thisValue, "toTimeString").time).toTimeString()],
    ["toUTCString", 0, (thisValue) => new Date(self(thisValue, "toUTCString").time).toUTCString()],
    ["toGMTString", 0, (thisValue) => new Date(self(thisValue, "toGMTString").time).toUTCString()],
+    ...(["toLocaleString", "toLocaleDateString", "toLocaleTimeString"] as const).map(
+      (name): Method => [
+        name,
+        0,
+        (thisValue) => new Date(self(thisValue, name).time)[name]("en-US", { timeZone: "UTC" }),
+      ],
+    ),
    ...getters.map((name): Method => [name, 0, (thisValue) => new Date(self(thisValue, name).time)[name]()]),
    ...setters.map(
      ([name, length]): Method => [
@@ -0,0 +1,137 @@
+import { Effect } from "effect"
+import { constructor, methods, prototypeFrom, receiver, requiresNew } from "../interpreter/native.js"
+import { IteratorSymbol, typeError } from "../interpreter/model.js"
+import {
+  define,
+  entries,
+  get,
+  hidden,
+  Arr,
+  HeadersObj,
+  IteratorObj,
+  Obj,
+  coerceToString,
+  isRuntimeReference,
+  type Value,
+} from "../interpreter/objects.js"
+import { applyCollectionCallback } from "../interpreter/callback.js"
+import type { Interpreter } from "../interpreter/interpreter.js"
+import { readPairs } from "./url.js"
+
+// The host validates header names and values and throws its own TypeError; the program gets one of its own.
+const attempt = <T>(run: () => T): T => {
+  try {
+    return run()
+  } catch (error) {
+    throw typeError(error instanceof Error ? error.message : String(error))
+  }
+}
+
+const constructHeaders = <R>(ctx: Interpreter<R>, init: Value, proto: Obj): Effect.Effect<HeadersObj, unknown, R> => {
+  const wrap = (headers: Headers) => new HeadersObj(proto, headers)
+  if (init === undefined) return Effect.succeed(wrap(new Headers()))
+  return Effect.gen(function* () {
+    const pairs = init instanceof Obj ? yield* readPairs(ctx, init, "new Headers(...)") : undefined
+    if (pairs !== undefined) return wrap(attempt(() => new Headers(pairs)))
+    if (!(init instanceof Obj) || isRuntimeReference(init)) {
+      throw typeError("new Headers(...) expects a record of names to values, iterable [name, value] pairs, or Headers.")
+    }
+    return wrap(
+      attempt(() => new Headers(Object.fromEntries(entries(init).map(([key, value]) => [key, coerceToString(value)])))),
+    )
+  })
+}
+
+export const headersGlobal = <R>(ctx: Interpreter<R>) => {
+  const builtins = ctx.builtins
+  const proto = builtins.Headers
+  const headers = constructor<R>(builtins, proto, {
+    name: "Headers",
+    call: requiresNew("Headers"),
+    construct: (args, newTarget) => constructHeaders(ctx, args[0], prototypeFrom(newTarget, proto)),
+  })
+  const self = (thisValue: Value, name: string) => receiver(HeadersObj, thisValue, `Headers.prototype.${name}`)
+  const wrap = (items: Array<Value>) => new Arr(builtins.Array, items)
+  const arg = (args: Array<Value>, index: number): string => coerceToString(args[index])
+  const requireArgs = (name: string, args: Array<Value>, count: number): void => {
+    if (args.length < count) throw typeError(`Headers.${name} requires ${count} argument${count === 1 ? "" : "s"}.`)
+  }
+  methods(builtins, proto, [
+    [
+      "append",
+      2,
+      (thisValue, args) => {
+        requireArgs("append", args, 2)
+        const target = self(thisValue, "append").headers
+        attempt(() => target.append(arg(args, 0), arg(args, 1)))
+        return undefined
+      },
+    ],
+    [
+      "delete",
+      1,
+      (thisValue, args) => {
+        requireArgs("delete", args, 1)
+        const target = self(thisValue, "delete").headers
+        attempt(() => target.delete(arg(args, 0)))
+        return undefined
+      },
+    ],
+    [
+      "get",
+      1,
+      (thisValue, args) => {
+        requireArgs("get", args, 1)
+        const target = self(thisValue, "get").headers
+        return attempt(() => target.get(arg(args, 0)))
+      },
+    ],
+    ["getSetCookie", 0, (thisValue) => wrap(self(thisValue, "getSetCookie").headers.getSetCookie())],
+    [
+      "has",
+      1,
+      (thisValue, args) => {
+        requireArgs("has", args, 1)
+        const target = self(thisValue, "has").headers
+        return attempt(() => target.has(arg(args, 0)))
+      },
+    ],
+    [
+      "set",
+      2,
+      (thisValue, args) => {
+        requireArgs("set", args, 2)
+        const target = self(thisValue, "set").headers
+        attempt(() => target.set(arg(args, 0), arg(args, 1)))
+        return undefined
+      },
+    ],
+    // Iterator.from because Bun's Headers typings predate iterator helpers; the runtime iterators already have them.
+    [
+      "keys",
+      0,
+      (thisValue) => new IteratorObj(builtins.Iterator, Iterator.from(self(thisValue, "keys").headers.keys())),
+    ],
+    [
+      "values",
+      0,
+      (thisValue) => new IteratorObj(builtins.Iterator, Iterator.from(self(thisValue, "values").headers.values())),
+    ],
+    ["entries", 0, (thisValue) => new IteratorObj(builtins.Iterator, self(thisValue, "entries").iterator(builtins))],
+    [
+      "forEach",
+      1,
+      (thisValue, args) => {
+        requireArgs("forEach", args, 1)
+        const target = self(thisValue, "forEach")
+        const apply = applyCollectionCallback(ctx, args[0], "Headers.forEach")
+        return Effect.gen(function* () {
+          for (const [key, value] of Array.from(target.headers.entries())) yield* apply([value, key, target])
+          return undefined
+        })
+      },
+    ],
+  ])
+  define(proto, IteratorSymbol, get(proto, "entries"), hidden)
+  return headers
+}
@@ -0,0 +1,19 @@
+import { methods, receiver } from "../interpreter/native.js"
+import { IteratorObj, record } from "../interpreter/objects.js"
+import type { Interpreter } from "../interpreter/interpreter.js"
+
+// Every built-in collection iterator shares the Iterator prototype; JS gives each collection its own, which is only
+// observable through getPrototypeOf.
+export const iteratorGlobals = <R>(ctx: Interpreter<R>): void => {
+  const builtins = ctx.builtins
+  methods(builtins, builtins.Iterator, [
+    [
+      "next",
+      0,
+      (thisValue) => {
+        const step = receiver(IteratorObj, thisValue, "Iterator.prototype.next").source.next()
+        return record(builtins.Object, { value: step.value, done: Boolean(step.done) })
+      },
+    ],
+  ])
+}
@@ -6,7 +6,7 @@ import { checkStringLength } from "../interpreter/limits.js"
 import { syntaxError, typeError } from "../interpreter/model.js"
 import { typeofValue } from "../interpreter/references.js"
 import { fromJson, toJson } from "../data.js"
-import { get, keys, Arr, Obj, record, remove, set } from "../interpreter/objects.js"
+import { get, keys, Arr, Obj, record, remove, set, type Value } from "../interpreter/objects.js"

 export const jsonGlobal = <R>(ctx: Interpreter<R>) => {
  const json = new Obj(ctx.builtins.Object)
@@ -17,7 +17,7 @@ export const jsonGlobal = <R>(ctx: Interpreter<R>) => {
  return json
 }

-const parse = <R>(ctx: Interpreter<R>, args: Array<unknown>): Effect.Effect<unknown, unknown, R> => {
+const parse = <R>(ctx: Interpreter<R>, args: Array<Value>): Effect.Effect<Value, unknown, R> => {
  const text = args[0]
  if (typeof text !== "string") throw typeError("JSON.parse expects a string.")

@@ -31,7 +31,7 @@ const parse = <R>(ctx: Interpreter<R>, args: Array<unknown>): Effect.Effect<unkn
  if (typeofValue(args[1]) !== "function") return Effect.succeed(parsed)

  const apply = applyCollectionCallback(ctx, args[1], "JSON.parse")
-  const visit = (holder: Obj, key: string): Effect.Effect<unknown, unknown, R> =>
+  const visit = (holder: Obj, key: string): Effect.Effect<Value, unknown, R> =>
    Effect.gen(function* () {
      const value = get(holder, key)
      if (value instanceof Obj) {
@@ -46,7 +46,7 @@ const parse = <R>(ctx: Interpreter<R>, args: Array<unknown>): Effect.Effect<unkn
  return visit(record(ctx.builtins.Object, { "": parsed }), "")
 }

-const stringify = <R>(ctx: Interpreter<R>, args: Array<unknown>): Effect.Effect<unknown, unknown, R> => {
+const stringify = <R>(ctx: Interpreter<R>, args: Array<Value>): Effect.Effect<Value, unknown, R> => {
  const space = args[2]
  const indent = typeof space === "number" || typeof space === "string" ? space : undefined
  const replacer = args[1]
@@ -1,7 +1,7 @@
 import { Effect } from "effect"
 import { constants, type Method, methods } from "../interpreter/native.js"
 import { typeError } from "../interpreter/model.js"
-import { Obj } from "../interpreter/objects.js"
+import { Obj, type Value } from "../interpreter/objects.js"
 import { preserveConsumerError } from "../interpreter/callback.js"
 import type { Interpreter } from "../interpreter/interpreter.js"

@@ -14,7 +14,7 @@ declare global {

 // Validate only the arguments a method consumes; like JS, extras are ignored
 // (so built-ins work as callbacks receiving (element, index, array)).
-const number = (name: string, args: Array<unknown>, index: number): number => {
+const number = (name: string, args: Array<Value>, index: number): number => {
  if (index >= args.length) return Number.NaN
  const arg = args[index]
  if (typeof arg !== "number") throw typeError(`Math.${name} expects number arguments.`)
@@ -1,7 +1,8 @@
 import { constructor, constants, methods } from "../interpreter/native.js"
+import { coerceToString, type Value } from "../interpreter/objects.js"
 import { rangeError, typeError } from "../interpreter/model.js"
 import type { Interpreter } from "../interpreter/interpreter.js"
-import { coercion, coerceToString } from "./value.js"
+import { coercion } from "./value.js"

 export const numberGlobal = <R>(ctx: Interpreter<R>) => {
  const builtins = ctx.builtins
@@ -39,17 +40,18 @@ export const numberGlobal = <R>(ctx: Interpreter<R>) => {
    ["parseFloat", 1, (_, args) => parseFloat(coerceToString(args[0]))],
  ])

-  const self = (thisValue: unknown, name: string): number => {
+  const self = (thisValue: Value, name: string): number => {
    if (typeof thisValue === "number") return thisValue
    throw typeError(`Number.prototype.${name} requires that 'this' be a Number.`)
  }
-  const optNum = (name: string, arg: unknown): number | undefined => {
+  const optNum = (name: string, arg: Value): number | undefined => {
    if (arg === undefined) return undefined
    if (typeof arg !== "number") throw typeError(`Number.${name} expects a number argument.`)
    return arg
  }
  methods(builtins, builtins.Number, [
    ["toFixed", 1, (thisValue, args) => self(thisValue, "toFixed").toFixed(optNum("toFixed", args[0]))],
+    ["toLocaleString", 0, (thisValue) => self(thisValue, "toLocaleString").toLocaleString("en-US")],
    [
      "toExponential",
      1,
@@ -88,7 +90,7 @@ export const booleanGlobal = <R>(ctx: Interpreter<R>) => {
    length: 1,
    call: coercion(ctx, "Boolean").call,
  })
-  const self = (thisValue: unknown, name: string): boolean => {
+  const self = (thisValue: Value, name: string): boolean => {
    if (typeof thisValue === "boolean") return thisValue
    throw typeError(`Boolean.prototype.${name} requires that 'this' be a Boolean.`)
  }
@@ -9,7 +9,6 @@ import {
  typeError,
 } from "../interpreter/model.js"
 import {
-  Callable,
  define,
  entries,
  enumerableKeys,
@@ -20,23 +19,20 @@ import {
  keys,
  own,
  Arr,
-  Bytes,
-  DateObj,
-  ErrorObj,
  Obj,
  PromiseObj,
-  RegExpObj,
  set,
+  coerceToString,
+  type Value,
 } from "../interpreter/objects.js"
 import { containsOpaqueReference, describeValue, rejectCircularInsertion } from "../interpreter/references.js"
-import { preserveConsumerError } from "../interpreter/callback.js"
+import { invoke, preserveConsumerError } from "../interpreter/callback.js"
 import type { Interpreter } from "../interpreter/interpreter.js"
 import { ToolReference } from "../tool-runtime.js"
 import { groupBy } from "./collections.js"
-import { coerceToString } from "./value.js"

 // ToObject for enumeration.
-export const enumerableSource = <R>(ctx: Interpreter<R>, label: string, value: unknown, node?: AstNode): Obj => {
+export const enumerableSource = <R>(ctx: Interpreter<R>, label: string, value: Value, node?: AstNode): Obj => {
  if (value === null || value === undefined) {
    throw typeError(`${label} cannot convert ${describeValue(value)} to an object.`, node)
  }
@@ -54,7 +50,7 @@ export const enumerableSource = <R>(ctx: Interpreter<R>, label: string, value: u
  return new Obj(ctx.builtins.Object)
 }

-export const objectAssign = <R>(ctx: Interpreter<R>, args: Array<unknown>): unknown => {
+export const objectAssign = <R>(ctx: Interpreter<R>, args: Array<Value>): Value => {
  const target = args[0]
  // JS would box a primitive target; wrappers and primitives cannot hold fields here.
  if (!(target instanceof Obj)) {
@@ -75,7 +71,7 @@ export const objectAssign = <R>(ctx: Interpreter<R>, args: Array<unknown>): unkn
  return target
 }

-const objectFromEntries = <R>(ctx: Interpreter<R>, source: unknown): Effect.Effect<Obj, unknown, R> => {
+const objectFromEntries = <R>(ctx: Interpreter<R>, source: Value): Effect.Effect<Obj, unknown, R> => {
  const out = new Obj(ctx.builtins.Object)
  return Effect.gen(function* () {
    const cursor = yield* ctx.iterate(source)
@@ -98,29 +94,24 @@ const objectFromEntries = <R>(ctx: Interpreter<R>, source: unknown): Effect.Effe
  })
 }

-export const classTag = (value: unknown): string => {
+const classTag = (value: Value): string => {
  if (value === null) return "Null"
  if (value === undefined) return "Undefined"
-  if (value instanceof Arr) return "Array"
-  if (value instanceof Callable) return "Function"
-  if (value instanceof ErrorObj) return "Error"
-  if (value instanceof DateObj) return "Date"
-  if (value instanceof RegExpObj) return "RegExp"
-  if (value instanceof Bytes) return "Uint8Array"
+  if (value instanceof Obj) return value.tag
  if (typeof value === "string") return "String"
  if (typeof value === "number") return "Number"
  if (typeof value === "boolean") return "Boolean"
  return "Object"
 }

-const propertyKey = (value: unknown): PropertyKey =>
+const propertyKey = (value: Value): PropertyKey =>
  value === AsyncIteratorSymbol || value === IteratorSymbol ? value : coerceToString(value)

 // Object constructs identically with or without new, like JS. Only `keys` copies its result into the
 // program; `values`, `entries`, `assign`, and `fromEntries` hand back the program's own values.
 export const objectGlobal = <R>(ctx: Interpreter<R>) => {
  const builtins = ctx.builtins
-  const construct = (args: Array<unknown>): unknown => {
+  const construct = (args: Array<Value>): Value => {
    const first = args[0]
    if (first === null || first === undefined) return new Obj(builtins.Object)
    if (first instanceof Obj) return first
@@ -196,7 +187,7 @@ export const objectGlobal = <R>(ctx: Interpreter<R>) => {
        true,
    ],
    ["toString", 0, (thisValue) => `[object ${classTag(thisValue)}]`],
-    ["toLocaleString", 0, (thisValue) => `[object ${classTag(thisValue)}]`],
+    ["toLocaleString", 0, (thisValue) => invoke(ctx, thisValue, "toString", "Object.prototype.toLocaleString")],
    [
      "valueOf",
      0,
@@ -2,9 +2,18 @@ import { Effect } from "effect"
 import type { Builtins } from "../interpreter/intrinsics.js"
 import { constructor, type Method, methods, prototypeFrom, receiver } from "../interpreter/native.js"
 import { syntaxError, typeError } from "../interpreter/model.js"
-import { define, defineAccessor, Arr, Obj, RegExpObj, record } from "../interpreter/objects.js"
+import {
+  define,
+  defineAccessor,
+  Arr,
+  Obj,
+  RegExpObj,
+  record,
+  coerceToNumber,
+  coerceToString,
+  type Value,
+} from "../interpreter/objects.js"
 import type { Interpreter } from "../interpreter/interpreter.js"
-import { coerceToNumber, coerceToString } from "./value.js"

 const flagProperties = [
  "hasIndices",
@@ -23,7 +32,7 @@ const regexFailureReason = (error: unknown): string =>
 const escapeRegexHint =
  'To match special characters like ( ) [ ] { } + * ? . literally, escape them with a backslash (e.g. "\\\\(") or test for them with String.includes instead.'

-export const toHostRegex = (arg: unknown, method: string, extraFlags = ""): RegExp => {
+export const toHostRegex = (arg: Value, method: string, extraFlags = ""): RegExp => {
  // Native parity: an undefined pattern behaves as an empty pattern.
  if (arg === undefined) return new RegExp("", extraFlags)
  if (arg instanceof RegExpObj) return arg.regex
@@ -53,7 +62,7 @@ export const matchToValue = (builtins: Builtins, match: RegExpMatchArray): Arr =
  return result
 }

-export const constructRegExp = (builtins: Builtins, args: Array<unknown>, proto: Obj = builtins.RegExp): RegExpObj => {
+export const constructRegExp = (builtins: Builtins, args: Array<Value>, proto: Obj = builtins.RegExp): RegExpObj => {
  const first = args[0]
  const pattern = first instanceof RegExpObj ? first.regex.source : first === undefined ? "" : coerceToString(first)
  const flagsArg = args[1]
@@ -96,7 +105,7 @@ export const regexpGlobal = <R>(ctx: Interpreter<R>) => {
    ],
  ])

-  const self = (thisValue: unknown, name: string) => receiver(RegExpObj, thisValue, `RegExp.prototype.${name}`)
+  const self = (thisValue: Value, name: string) => receiver(RegExpObj, thisValue, `RegExp.prototype.${name}`)
  defineAccessor(proto, "source", (thisValue) => self(thisValue, "source").regex.source)
  defineAccessor(proto, "flags", (thisValue) => self(thisValue, "flags").regex.flags)
  // The host regex holds the only lastIndex, so exec/test and the String methods share one counter.
@@ -1,16 +1,26 @@
 import { Effect } from "effect"
-import { constructor, type Method, methods } from "../interpreter/native.js"
+import { constructor, fn, type Impl, type Method, methods } from "../interpreter/native.js"
 import { checkArrayLength, checkStringLength } from "../interpreter/limits.js"
-import { invalidData, rangeError, typeError } from "../interpreter/model.js"
-import { Arr, PromiseObj, RegExpObj, record } from "../interpreter/objects.js"
+import { invalidData, IteratorSymbol, rangeError, typeError } from "../interpreter/model.js"
+import {
+  define,
+  hidden,
+  Arr,
+  IteratorObj,
+  RegExpObj,
+  record,
+  coerceToNumber,
+  coerceToString,
+  type Value,
+} from "../interpreter/objects.js"
 import { containsOpaqueReference, typeofValue } from "../interpreter/references.js"
 import { applyCollectionCallback, isSupportedCallback } from "../interpreter/callback.js"
 import type { Interpreter } from "../interpreter/interpreter.js"
 import { matchToValue, toHostRegex } from "./regexp.js"
-import { coerceToNumber, coerceToString, coercion } from "./value.js"
+import { coercion } from "./value.js"

 // console is intercepted by the interpreter before reaching here.
-const requireDataArgument = (name: string, index: number, arg: unknown): unknown => {
+const requireDataArgument = (name: string, index: number, arg: Value): Value => {
  if (containsOpaqueReference(arg)) {
    throw invalidData(`String.${name} expects argument ${index + 1} to be a data value.`)
  }
@@ -29,21 +39,23 @@ const replaceWithCallback = <R>(
  ctx: Interpreter<R>,
  value: string,
  name: "replace" | "replaceAll",
-  args: Array<unknown>,
-): Effect.Effect<unknown, unknown, R> => {
+  args: Array<Value>,
+): Effect.Effect<Value, unknown, R> => {
  const builtins = ctx.builtins
  const apply = applyCollectionCallback(ctx, args[1], `String.${name}`)
-  const matches: Array<{ readonly match: string; readonly offset: number; readonly args: Array<unknown> }> = []
-  const collect = (...callbackArgs: Array<unknown>): string => {
+  const matches: Array<{ readonly match: string; readonly offset: number; readonly args: Array<Value> }> = []
+  // The host calls back with (match, ...captures, offset, string, groups?); only groups is not already a Value.
+  const collect = (
+    ...callbackArgs: Array<string | number | undefined | Record<string, string | undefined>>
+  ): string => {
    const match = callbackArgs[0]
-    const groups = callbackArgs[callbackArgs.length - 1]
-    const hasGroups = groups !== null && typeof groups === "object"
+    const hasGroups = typeof callbackArgs.at(-1) === "object"
    const offset = callbackArgs[callbackArgs.length - (hasGroups ? 3 : 2)]
    if (typeof match !== "string" || typeof offset !== "number") {
      throw typeError(`String.${name} produced an invalid replacement match.`)
    }
-    if (hasGroups) callbackArgs[callbackArgs.length - 1] = record(builtins.Object, groups as Record<string, unknown>)
-    matches.push({ match, offset, args: callbackArgs })
+    const args = callbackArgs.map((arg) => (typeof arg === "object" ? record(builtins.Object, arg) : arg))
+    matches.push({ match, offset, args })
    return match
  }

@@ -63,10 +75,7 @@ const replaceWithCallback = <R>(
    let end = 0
    for (const match of matches) {
      const replacement = yield* apply(match.args)
-      output.push(
-        value.slice(end, match.offset),
-        replacement instanceof PromiseObj ? "[object Promise]" : coerceToString(replacement),
-      )
+      output.push(value.slice(end, match.offset), coerceToString(replacement))
      end = match.offset + match.match.length
    }
    output.push(value.slice(end))
@@ -99,7 +108,7 @@ export const stringGlobal = <R>(ctx: Interpreter<R>) => {
    codeUnits("fromCodePoint", String.fromCodePoint),
  ])

-  const self = (thisValue: unknown, name: string): string => {
+  const self = (thisValue: Value, name: string): string => {
    if (typeof thisValue === "string") return thisValue
    if (thisValue === null || thisValue === undefined) {
      throw typeError(`String.prototype.${name} called on null or undefined.`)
@@ -107,26 +116,26 @@ export const stringGlobal = <R>(ctx: Interpreter<R>) => {
    return coerceToString(thisValue)
  }
  // Coerce arguments like native JS; opaque runtime references still reject.
-  const str = (name: string, args: Array<unknown>, index: number): string =>
+  const str = (name: string, args: Array<Value>, index: number): string =>
    coerceToString(requireDataArgument(name, index, args[index]))
-  const num = (name: string, args: Array<unknown>, index: number): number =>
+  const num = (name: string, args: Array<Value>, index: number): number =>
    coerceToNumber(requireDataArgument(name, index, args[index]))
-  const optNum = (name: string, args: Array<unknown>, index: number): number | undefined =>
+  const optNum = (name: string, args: Array<Value>, index: number): number | undefined =>
    args[index] === undefined ? undefined : num(name, args, index)
-  const optStr = (name: string, args: Array<unknown>, index: number): string | undefined =>
+  const optStr = (name: string, args: Array<Value>, index: number): string | undefined =>
    args[index] === undefined ? undefined : str(name, args, index)
-  const rejectRegex = (name: string, args: Array<unknown>): void => {
+  const rejectRegex = (name: string, args: Array<Value>): void => {
    if (args[0] instanceof RegExpObj) {
      throw typeError(
        `String.${name} cannot take a regular expression; use regex.test(string) or String.search instead.`,
      )
    }
  }
-  const simple = (name: string, length: number, op: (value: string, args: Array<unknown>) => unknown): Method => [
-    name,
-    length,
-    (thisValue, args) => op(self(thisValue, name), args),
-  ]
+  const simple = (
+    name: string,
+    length: number,
+    op: (value: string, args: Array<Value>) => ReturnType<Impl>,
+  ): Method => [name, length, (thisValue, args) => op(self(thisValue, name), args)]
  const replace = (name: "replace" | "replaceAll") =>
    simple(name, 2, (value, args) => {
      if (isSupportedCallback(args[1])) return replaceWithCallback(ctx, value, name, args)
@@ -150,6 +159,8 @@ export const stringGlobal = <R>(ctx: Interpreter<R>) => {
    simple("valueOf", 0, (value) => value),
    simple("toLowerCase", 0, (value) => value.toLowerCase()),
    simple("toUpperCase", 0, (value) => value.toUpperCase()),
+    simple("toLocaleLowerCase", 0, (value) => value.toLowerCase()),
+    simple("toLocaleUpperCase", 0, (value) => value.toUpperCase()),
    simple("trim", 0, (value) => value.trim()),
    simple("trimStart", 0, (value) => value.trimStart()),
    simple("trimLeft", 0, (value) => value.trimStart()),
@@ -216,7 +227,7 @@ export const stringGlobal = <R>(ctx: Interpreter<R>) => {
          `String.matchAll requires a regular expression with the global (g) flag: write /${pattern.source}/${pattern.flags}g, or use String.match for a single match.`,
        )
      }
-      const matches: Array<unknown> = []
+      const matches: Array<Value> = []
      for (const match of value.matchAll(pattern)) {
        checkArrayLength(matches.length + 1)
        matches.push(matchToValue(builtins, match))
@@ -258,5 +269,16 @@ export const stringGlobal = <R>(ctx: Interpreter<R>) => {
      return joined
    }),
  ])
+  define(
+    builtins.String,
+    IteratorSymbol,
+    fn(
+      builtins,
+      "[Symbol.iterator]",
+      0,
+      (thisValue) => new IteratorObj(builtins.Iterator, self(thisValue, "[Symbol.iterator]")[Symbol.iterator]()),
+    ),
+    hidden,
+  )
  return string
 }
@@ -1,11 +1,23 @@
 import { Effect } from "effect"
 import { constructor, fn, type Method, methods, prototypeFrom, receiver, requiresNew } from "../interpreter/native.js"
-import { PendingThrow, typeError, uriError } from "../interpreter/model.js"
-import { defineAccessor, entries, isWrapper, Arr, Obj, URLObj, URLSearchParamsObj } from "../interpreter/objects.js"
-import { isRuntimeReference } from "../interpreter/references.js"
+import { IteratorSymbol, PendingThrow, typeError, uriError } from "../interpreter/model.js"
+import {
+  define,
+  defineAccessor,
+  entries,
+  get,
+  hidden,
+  Arr,
+  IteratorObj,
+  Obj,
+  URLObj,
+  URLSearchParamsObj,
+  coerceToString,
+  isRuntimeReference,
+  type Value,
+} from "../interpreter/objects.js"
 import { applyCollectionCallback, preserveConsumerError } from "../interpreter/callback.js"
 import type { Interpreter } from "../interpreter/interpreter.js"
-import { coerceToString } from "./value.js"

 const urlProperties = [
  "href",
@@ -40,12 +52,12 @@ export const uriGlobal = <R>(ctx: Interpreter<R>, name: UriFunction) =>
    }
  })

-const urlArgument = (value: unknown): string => (value instanceof URLObj ? value.url.href : coerceToString(value))
+const urlArgument = (value: Value): string => (value instanceof URLObj ? value.url.href : coerceToString(value))

 export const urlGlobal = <R>(ctx: Interpreter<R>) => {
  const builtins = ctx.builtins
  const proto = builtins.URL
-  const construct = (args: Array<unknown>, into: Obj): URLObj => {
+  const construct = (args: Array<Value>, into: Obj): URLObj => {
    if (args.length === 0) {
      throw typeError("new URL(...) requires a URL string and an optional base URL.")
    }
@@ -80,7 +92,7 @@ export const urlGlobal = <R>(ctx: Interpreter<R>) => {
  ]
  methods(builtins, url, [parse("canParse"), parse("parse")])

-  const self = (thisValue: unknown, name: string) => receiver(URLObj, thisValue, `URL.prototype.${name}`)
+  const self = (thisValue: Value, name: string) => receiver(URLObj, thisValue, `URL.prototype.${name}`)
  for (const name of urlProperties) {
    defineAccessor(
      proto,
@@ -107,12 +119,10 @@ export const urlGlobal = <R>(ctx: Interpreter<R>) => {
  return url
 }

-const readPair = <R>(ctx: Interpreter<R>, value: unknown): Effect.Effect<Array<string>, unknown, R> =>
+const readPair = <R>(ctx: Interpreter<R>, value: Value, label: string): Effect.Effect<Array<string>, unknown, R> =>
  Effect.gen(function* () {
    const cursor = yield* ctx.iterate(value)
-    if (cursor === undefined) {
-      throw typeError("new URLSearchParams(...) expects iterable [name, value] pairs.")
-    }
+    if (cursor === undefined) throw typeError(`${label} expects iterable [name, value] pairs.`)
    const items: Array<string> = []
    while (true) {
      const step = yield* cursor.next
@@ -126,9 +136,32 @@ const readPair = <R>(ctx: Interpreter<R>, value: unknown): Effect.Effect<Array<s
    }
  })

+/**
+ * Reads a synchronous iterable of `[name, value]` pairs as strings; `undefined` when `init` is not iterable. As in
+ * WebIDL, the whole sequence is converted before any pair's length is checked.
+ */
+export const readPairs = <R>(
+  ctx: Interpreter<R>,
+  init: Value,
+  label: string,
+): Effect.Effect<Array<[string, string]> | undefined, unknown, R> =>
+  Effect.gen(function* () {
+    const cursor = yield* ctx.iterate(init)
+    if (cursor === undefined) return undefined
+    const pairs: Array<Array<string>> = []
+    while (true) {
+      const step = yield* cursor.next
+      if (step.done) {
+        if (pairs.some((entry) => entry.length !== 2)) throw typeError(`${label} expects iterable [name, value] pairs.`)
+        return pairs as Array<[string, string]>
+      }
+      pairs.push(yield* preserveConsumerError(cursor, readPair(ctx, step.value, label)))
+    }
+  })
+
 const constructURLSearchParams = <R>(
  ctx: Interpreter<R>,
-  init: unknown,
+  init: Value,
  proto: Obj,
 ): Effect.Effect<URLSearchParamsObj, unknown, R> => {
  const wrap = (params: URLSearchParams) => new URLSearchParamsObj(proto, params)
@@ -139,24 +172,11 @@ const constructURLSearchParams = <R>(
    return Effect.succeed(wrap(new URLSearchParams(coerceToString(init))))
  }
  return Effect.gen(function* () {
-    const cursor = yield* ctx.iterate(init)
-    if (cursor !== undefined) {
-      const pairs: Array<Array<string>> = []
-      while (true) {
-        const step = yield* cursor.next
-        if (step.done) {
-          if (pairs.some((entry) => entry.length !== 2)) {
-            throw typeError("new URLSearchParams(...) expects iterable [name, value] pairs.")
-          }
-          return wrap(new URLSearchParams(pairs.map((entry): [string, string] => [entry[0] ?? "", entry[1] ?? ""])))
-        }
-        pairs.push(yield* preserveConsumerError(cursor, readPair(ctx, step.value)))
-      }
-    }
+    const pairs = yield* readPairs(ctx, init, "new URLSearchParams(...)")
+    if (pairs !== undefined) return wrap(new URLSearchParams(pairs))
    if (isRuntimeReference(init)) {
      throw typeError("new URLSearchParams(...) expects a query string, data object, or synchronous iterable pairs.")
    }
-    if (isWrapper(init)) return wrap(new URLSearchParams())
    if (!(init instanceof Obj)) {
      throw typeError(
        "new URLSearchParams(...) expects a query string, data object, iterable pairs, or URLSearchParams.",
@@ -176,11 +196,11 @@ export const urlSearchParamsGlobal = <R>(ctx: Interpreter<R>) => {
    call: requiresNew("URLSearchParams"),
    construct: (args, newTarget) => constructURLSearchParams(ctx, args[0], prototypeFrom(newTarget, proto)),
  })
-  const self = (thisValue: unknown, name: string) =>
+  const self = (thisValue: Value, name: string) =>
    receiver(URLSearchParamsObj, thisValue, `URLSearchParams.prototype.${name}`)
-  const wrap = (items: Array<unknown>) => new Arr(builtins.Array, items)
-  const arg = (args: Array<unknown>, index: number): string => coerceToString(args[index])
-  const requireArgs = (name: string, args: Array<unknown>, count: number): void => {
+  const wrap = (items: Array<Value>) => new Arr(builtins.Array, items)
+  const arg = (args: Array<Value>, index: number): string => coerceToString(args[index])
+  const requireArgs = (name: string, args: Array<Value>, count: number): void => {
    if (args.length < count) {
      throw typeError(`URLSearchParams.${name} requires ${count} argument${count === 1 ? "" : "s"}.`)
    }
@@ -249,14 +269,9 @@ export const urlSearchParamsGlobal = <R>(ctx: Interpreter<R>) => {
        return undefined
      },
    ],
-    ["keys", 0, (thisValue) => wrap(Array.from(self(thisValue, "keys").params.keys()))],
-    ["values", 0, (thisValue) => wrap(Array.from(self(thisValue, "values").params.values()))],
-    [
-      "entries",
-      0,
-      (thisValue) =>
-        wrap(Array.from(self(thisValue, "entries").params.entries(), ([key, value]) => wrap([key, value]))),
-    ],
+    ["keys", 0, (thisValue) => new IteratorObj(builtins.Iterator, self(thisValue, "keys").params.keys())],
+    ["values", 0, (thisValue) => new IteratorObj(builtins.Iterator, self(thisValue, "values").params.values())],
+    ["entries", 0, (thisValue) => new IteratorObj(builtins.Iterator, self(thisValue, "entries").iterator(builtins))],
    ["toString", 0, (thisValue) => self(thisValue, "toString").params.toString()],
    [
      "forEach",
@@ -272,5 +287,6 @@ export const urlSearchParamsGlobal = <R>(ctx: Interpreter<R>) => {
      },
    ],
  ])
+  define(proto, IteratorSymbol, get(proto, "entries"), hidden)
  return searchParams
 }
@@ -1,62 +1,13 @@
 import { fn } from "../interpreter/native.js"
 import { typeError } from "../interpreter/model.js"
-import {
-  get,
-  isWrapper,
-  type Native,
-  Arr,
-  Bytes,
-  DateObj,
-  ErrorObj,
-  MapObj,
-  RegExpObj,
-  SetObj,
-  URLObj,
-  URLSearchParamsObj,
-} from "../interpreter/objects.js"
+import { coerceToNumber, coerceToString, type Native, type Value } from "../interpreter/objects.js"
 import type { Interpreter } from "../interpreter/interpreter.js"

 export const compoundOperators = new Set(["+=", "-=", "*=", "/=", "%=", "**=", "&=", "|=", "^=", "<<=", ">>=", ">>>="])

-/** The built-in string form of a value, without consulting program-defined `toString` methods. */
-export const coerceToString = (value: unknown): string => {
-  if (value === null) return "null"
-  if (value === undefined) return "undefined"
-  if (value instanceof DateObj) return Number.isFinite(value.time) ? new Date(value.time).toISOString() : "Invalid Date"
-  if (value instanceof RegExpObj) return `/${value.regex.source}/${value.regex.flags}`
-  if (value instanceof MapObj) return "[object Map]"
-  if (value instanceof SetObj) return "[object Set]"
-  if (value instanceof URLObj) return value.url.href
-  if (value instanceof URLSearchParamsObj) return value.params.toString()
-  if (value instanceof Bytes) return value.bytes.join(",")
-  if (value instanceof ErrorObj) {
-    // Match Error.prototype.toString: "name: message", or just one when the other is empty.
-    const name = get(value, "name")
-    const message = get(value, "message")
-    const shownName = typeof name === "string" ? name : "Error"
-    const shownMessage = typeof message === "string" ? message : ""
-    if (shownMessage === "") return shownName
-    if (shownName === "") return shownMessage
-    return `${shownName}: ${shownMessage}`
-  }
-  if (value instanceof Arr) {
-    return value.items.map((item) => (item === null || item === undefined ? "" : coerceToString(item))).join(",")
-  }
-  if (typeof value === "object") return "[object Object]"
-  return String(value)
-}
-
-export const coerceToNumber = (value: unknown): number => {
-  if (value instanceof DateObj) return value.time
-  if (value instanceof Bytes) return Number(coerceToString(value))
-  if (isWrapper(value)) return Number.NaN
-  if (value instanceof Arr) return Number(coerceToString(value))
-  return value !== null && typeof value === "object" ? Number.NaN : Number(value)
-}
-
 export type Coercion = "Number" | "String" | "Boolean" | "parseInt" | "parseFloat" | "isFinite" | "isNaN"

-const coerce = <R>(ctx: Interpreter<R>, name: Coercion, args: Array<unknown>): unknown => {
+const coerce = <R>(ctx: Interpreter<R>, name: Coercion, args: Array<Value>): Value => {
  // Native: Number() is 0 and String() is "", unlike their undefined-argument forms; the
  // other coercers match native through the undefined-argument path below.
  if (args.length === 0) {
@@ -64,15 +15,6 @@ const coerce = <R>(ctx: Interpreter<R>, name: Coercion, args: Array<unknown>): u
    if (name === "String") return ""
  }
  const raw = args[0]
-  if (isWrapper(raw)) {
-    if (name === "Boolean") return true
-    if (name === "Number") return coerceToNumber(raw)
-    if (name === "String") return coerceToString(raw)
-    if (name === "isFinite") return Number.isFinite(coerceToNumber(raw))
-    if (name === "isNaN") return Number.isNaN(coerceToNumber(raw))
-    if (name === "parseInt") return parseInt(coerceToString(raw))
-    return parseFloat(coerceToString(raw))
-  }
  if (name === "Number") return coerceToNumber(raw)
  if (name === "Boolean") return Boolean(raw)
  if (name === "isFinite") return Number.isFinite(coerceToNumber(raw))
@@ -1,9 +1,8 @@
 import { fn, methods } from "../interpreter/native.js"
 import { typeError } from "../interpreter/model.js"
-import { Bytes, Obj } from "../interpreter/objects.js"
+import { Bytes, Obj, coerceToString } from "../interpreter/objects.js"
 import { describeValue } from "../interpreter/references.js"
 import type { Interpreter } from "../interpreter/interpreter.js"
-import { coerceToString } from "./value.js"

 // WebIDL DOMString conversion: a missing argument is a TypeError, anything else stringifies. Invalid input is a
 // TypeError as well; browsers throw a DOMException named InvalidCharacterError, which CodeMode does not have.
@@ -298,21 +298,18 @@ const cases = [
  },
  {
    path: "test/built-ins/Array/prototype/keys/iteration.js",
-    code: `return ["a", "b", "c"].keys()`,
-    expected: [0, 1, 2],
+    code: `const it = ["a", "b", "c"].keys(); return [it.next(), it.next(), it.next(), it.next()]`,
+    expected: [{ value: 0, done: false }, { value: 1, done: false }, { value: 2, done: false }, { done: true }],
  },
  {
    path: "test/built-ins/Array/prototype/values/iteration.js",
-    code: `return ["a", "b", "c"].values()`,
-    expected: ["a", "b", "c"],
+    code: `const it = ["a", "b", "c"].values(); return [it.next(), it.next(), it.next(), it.next()]`,
+    expected: [{ value: "a", done: false }, { value: "b", done: false }, { value: "c", done: false }, { done: true }],
  },
  {
    path: "test/built-ins/Array/prototype/entries/iteration.js",
-    code: `return ["a", "b"].entries()`,
-    expected: [
-      [0, "a"],
-      [1, "b"],
-    ],
+    code: `const it = ["a", "b"].entries(); return [it.next(), it.next(), it.next()]`,
+    expected: [{ value: [0, "a"], done: false }, { value: [1, "b"], done: false }, { done: true }],
  },
  {
    path: "test/built-ins/Array/isArray/15.4.3.2-0-3.js",
@@ -15,7 +15,23 @@ const error = async (code: string) => {
  return result.error
 }

+describe("source syntax", () => {
+  test("rejects TypeScript-only syntax", async () => {
+    expect((await error(`const value: number = 1; return value`)).kind).toBe("ParseError")
+  })
+})
+
 describe("error identity", () => {
+  test("Error.isError is true for every Error value and nothing else", async () => {
+    expect(
+      await value(`
+        const caught = (() => { try { null.foo } catch (error) { return error } })()
+        return [Error.isError(new Error("x")), Error.isError(new RangeError("x")), Error.isError(caught),
+          Error.isError({ name: "Error", message: "x" }), Error.isError("Error"), Error.isError(null)]
+      `),
+    ).toEqual([true, true, true, false, false, false])
+  })
+
  test("awaiting the same rejected promise twice yields the same error object", async () => {
    expect(
      await value(`
@@ -89,6 +105,24 @@ describe("uncaught program throws", () => {
  })
 })

+describe("source locations", () => {
+  test("uses the submitted line and 1-based column", async () => {
+    const failure = await error("const value = 1\nreturn value()")
+    expect(failure.location).toEqual({ line: 2, column: 8 })
+    expect(failure.message).toBe("TypeError: value is not a function. (line 2, col 8)")
+  })
+
+  test("names a missing method on a call instead of the previous line", async () => {
+    const failure = await error(`// Try search with different namespaces
+for (const ns of ["github", "tools.github", "tools", ""]) {
+  const s = await search({query: "star", namespace: ns, limit: 100}).catch(e=>({items:[],error:String(e)}));
+  return s
+}`)
+    expect(failure.location).toEqual({ line: 3, column: 19 })
+    expect(failure.message).toBe("TypeError: search(...).catch is not a function. (line 3, col 19)")
+  })
+})
+
 describe("host errors escaping built-ins", () => {
  test("become the same-named program error", async () => {
    expect(
@@ -115,7 +149,7 @@ describe("host errors escaping built-ins", () => {
      "(line 1, col 14)",
    )
    expect((await error(`let p; p = Promise.resolve().then(() => p); return await p`)).message).toEndWith(
-      "(line 2, col 5)",
+      "(line 1, col 12)",
    )
  })

@@ -128,6 +128,34 @@ describe("values are converted at the boundary, never shared", () => {
    expect([...(held[0] as Set<{ z: number }>)][0]).toEqual({ z: 1 })
  })

+  test("Headers cross as copies in both directions", async () => {
+    const stored = new Headers({ "X-A": "1" })
+    const target = CodeMode.make({
+      extensions: [
+        Extension.make({
+          name: "http",
+          globals: {
+            headers: () => stored,
+            keep: (value: Headers) => {
+              held.push(value)
+              return value
+            },
+          },
+        }),
+      ],
+    })
+    held.length = 0
+    expect(
+      await value(
+        `const h = headers(); h.set("x-a", "2"); const back = keep(h); back.set("x-a", "3"); return [h instanceof Headers, h.get("x-a"), back === h, back.get("x-a"), [...back]]`,
+        target,
+      ),
+    ).toEqual([true, "2", false, "3", [["x-a", "3"]]])
+    expect(stored.get("x-a")).toBe("1")
+    expect(held[0]).toBeInstanceOf(Headers)
+    expect((held[0] as Headers).get("x-a")).toBe("2")
+  })
+
  test("bytes cross as copies in both directions; ArrayBuffer comes in as Uint8Array", async () => {
    const stored = new Uint8Array([1, 2, 3])
    const target = CodeMode.make({
@@ -192,8 +220,9 @@ describe("values are converted at the boundary, never shared", () => {
    expect(held[1]).toBeInstanceOf(Error)
  })

-  test("functions, promises, and symbols cannot be passed in", async () => {
+  test("functions, promises, iterators, and symbols cannot be passed in", async () => {
    expect((await failure(`keep(() => 1)`)).message).toContain("Argument 1 to keep contains a function")
+    expect((await failure(`keep([1].keys())`)).message).toContain("Argument 1 to keep contains an iterator")
    expect((await failure(`keep(later(1))`)).message).toContain("un-awaited Promise")
    expect((await failure(`keep(Symbol.iterator)`)).message).toContain("Argument 1 to keep contains a symbol")
  })
@@ -529,6 +529,6 @@ describe("Test262 for-await-of adaptations", () => {
    const result = await execute(`for await (const item of { values: [1, 2] }) {}`)
    expect(result.ok).toBe(false)
    if (result.ok) return
-    expect(result.error.message).toContain("or custom iterator value")
+    expect(result.error.message).toContain("requires an iterable value, received a data object")
  })
 })
@@ -1030,7 +1030,7 @@ describe("confined generators", () => {
        const params = new URLSearchParams(entries())
        return [events, params.toString()]
      `),
-    ).toEqual([["first", "second", "pair close", "outer close"], "%5Bobject+Object%5D=2"])
+    ).toEqual([["first", "second", "pair close", "outer close"], "%5Bobject+Promise%5D=2"])
  })

  test("validates URLSearchParams pair lengths after converting the outer sequence", async () => {
@@ -122,10 +122,10 @@ describe("Map.groupBy Test262 parity", () => {
          grouped.get(1),
          grouped.get("1"),
          grouped.has(stringable),
-          grouped.keys().length,
+          [...grouped.keys()].length,
          parity.get("even"),
          parity.get("odd"),
-          lengths.keys(),
+          [...lengths.keys()],
          lengths.get(5),
          lengths.get(4),
        ]
@@ -162,7 +162,7 @@ describe("Map.groupBy Test262 parity", () => {
      await value(`
        const grouped = Map.groupBy("🥰💩🙏😈", (char) => char < "🙏" ? "before" : "after")
        const empty = Map.groupBy([], () => { throw new Error("not called") })
-        return [grouped.keys(), grouped.get("before"), grouped.get("after"), empty.size]
+        return [[...grouped.keys()], grouped.get("before"), grouped.get("after"), empty.size]
      `),
    ).toEqual([["after", "before"], ["💩", "😈"], ["🥰", "🙏"], 0])
  })
@@ -502,9 +502,15 @@ describe("CodeMode-specific array behavior", () => {
    expect(err.message).toContain("circular")
  })

-  test("keys/values/entries return arrays usable with for...of and spread", async () => {
+  test("indexOf and lastIndexOf with no argument search for undefined", async () => {
+    expect(await value(`return [1, undefined, 3].indexOf()`)).toBe(1)
+    expect(await value(`return [1, undefined, 3].lastIndexOf()`)).toBe(1)
+    expect(await value(`return [1, 2, 3].indexOf()`)).toBe(-1)
+  })
+
+  test("keys/values/entries return iterators usable with for...of and spread", async () => {
    expect(await value(`return [...["x","y","z"].keys()]`)).toEqual([0, 1, 2])
-    expect(await value(`return ["x","y"].values()`)).toEqual(["x", "y"])
+    expect(await value(`return [...["x","y"].values()]`)).toEqual(["x", "y"])
    expect(
      await value(`
      const out = []
@@ -940,6 +946,12 @@ describe("coercion parity: unknown static members read as undefined", () => {
    expect(await value(`try { JSON.rawJSON("1") } catch (e) { return e.message }`)).toBe(
      "JSON.rawJSON is not a function.",
    )
+    expect(await value(`try { search({ query: "star" }).catch(() => 1) } catch (e) { return e.message }`)).toBe(
+      "search(...).catch is not a function.",
+    )
+    expect(
+      await value(`const foo = () => ({ bar: () => ({}) }); try { foo().bar().baz() } catch (e) { return e.message }`),
+    ).toBe("foo(...).bar(...).baz is not a function.")
  })

  test("built-ins are objects on a real prototype chain", async () => {
@@ -961,6 +973,17 @@ describe("coercion parity: unknown static members read as undefined", () => {
  })
 })

+describe("async function line breaks", () => {
+  test("a line break between function and the name is an async function", async () => {
+    expect(await value(`async function\nfoo() { return 1 }\nreturn await foo()`)).toBe(1)
+  })
+
+  test("a line break between async and function is not an async function", async () => {
+    const failure = await error(`async\nfunction foo() { return 1 }\nreturn foo()`)
+    expect(failure.message).toContain("Unknown identifier 'async'")
+  })
+})
+
 describe("functions are objects", () => {
  test("name follows NamedEvaluation and length counts required parameters", async () => {
    expect(
@@ -198,10 +198,10 @@ describe("Set composition Test262 parity", () => {
          keys: () => [-0],
        }
        return [
-          1 / new Set([1]).union(setlike).values()[1] === Infinity,
-          1 / new Set([0, 1, 2]).intersection(setlike).values()[0] === Infinity,
+          1 / [...new Set([1]).union(setlike)][1] === Infinity,
+          1 / [...new Set([0, 1, 2]).intersection(setlike)][0] === Infinity,
          [...new Set([0, 1]).difference(setlike)],
-          1 / new Set([1, 2]).symmetricDifference(setlike).values()[2] === Infinity,
+          1 / [...new Set([1, 2]).symmetricDifference(setlike)][2] === Infinity,
        ]
      `),
    ).toEqual([true, true, [1], true])
@@ -20,9 +20,9 @@ import { CodeMode, Tool } from "../src/index.js"

 // Standard-library value types: Date, RegExp, Map, Set. Programs use them as ordinary JS;
 // intra-CodeMode checkpoints (Object.* helpers, spread, coercion inputs) preserve the live
-// values, while at the host boundary (final result, tool arguments, JSON.stringify) they
-// serialize exactly as JSON.stringify would: Date -> ISO string (invalid -> null),
-// URL -> href, and RegExp/Map/Set/URLSearchParams -> {}.
+// values. JSON.stringify keeps Date -> ISO string (invalid -> null), URL -> href, and
+// RegExp/Map/Set/URLSearchParams -> {}. The host boundary matches that except URLSearchParams,
+// which cross as their query string, and Set, which crosses as an array.
 const run = (code: string) => Effect.runPromise(CodeMode.execute({ code, tools: {} }))
 const value = async (code: string) => {
  const result = await run(code)
@@ -635,6 +635,154 @@ describe("URL and URI helpers", () => {
  })
 })

+describe("Headers", () => {
+  test("constructs from records, pairs, Maps, and Headers; names fold to lowercase and values combine", async () => {
+    expect(
+      await value(`
+        const headers = new Headers({ "Content-Type": "text/plain", "X-Count": 1, "X-Null": null })
+        headers.append("Accept", "text/html")
+        headers.append("accept", "application/json")
+        headers.set("x-count", "2")
+        headers.delete("x-null")
+        const copy = new Headers(headers)
+        copy.set("content-type", "text/html")
+        return {
+          get: headers.get("content-type"),
+          missing: headers.get("x-missing"),
+          combined: headers.get("ACCEPT"),
+          has: [headers.has("Accept"), headers.has("x-null")],
+          count: headers.get("x-count"),
+          copied: [headers.get("content-type"), copy.get("content-type")],
+          pairs: [...new Headers([["b", "2"], ["A", "1"]])],
+          map: [...new Headers(new Map([["k", "v"]]))],
+          keys: [...headers.keys()],
+          values: [...headers.values()],
+          entries: [...headers.entries()],
+        }
+      `),
+    ).toEqual({
+      get: "text/plain",
+      missing: null,
+      combined: "text/html, application/json",
+      has: [true, false],
+      count: "2",
+      copied: ["text/plain", "text/html"],
+      pairs: [
+        ["a", "1"],
+        ["b", "2"],
+      ],
+      map: [["k", "v"]],
+      keys: ["accept", "content-type", "x-count"],
+      values: ["text/html, application/json", "text/plain", "2"],
+      entries: [
+        ["accept", "text/html, application/json"],
+        ["content-type", "text/plain"],
+        ["x-count", "2"],
+      ],
+    })
+  })
+
+  test("iterates in sorted order everywhere iteration is allowed, and getSetCookie keeps cookies apart", async () => {
+    expect(
+      await value(`
+        const headers = new Headers({ b: "2", a: "1" })
+        headers.append("Set-Cookie", "x=1")
+        headers.append("set-cookie", "y=2")
+        const seen = []
+        headers.forEach((value, name, self) => seen.push(name + "=" + value + ":" + (self === headers)))
+        const [first] = headers
+        function* pairs() { yield* headers }
+        return {
+          seen,
+          first,
+          spread: [...headers],
+          from: Array.from(headers).length,
+          generator: [...pairs()].length,
+          object: Object.fromEntries(headers),
+          cookies: headers.getSetCookie(),
+        }
+      `),
+    ).toEqual({
+      seen: ["a=1:true", "b=2:true", "set-cookie=x=1:true", "set-cookie=y=2:true"],
+      first: ["a", "1"],
+      spread: [
+        ["a", "1"],
+        ["b", "2"],
+        ["set-cookie", "x=1"],
+        ["set-cookie", "y=2"],
+      ],
+      from: 4,
+      generator: 4,
+      object: { a: "1", b: "2", "set-cookie": "y=2" },
+      cookies: ["x=1", "y=2"],
+    })
+  })
+
+  test("serializes as a name-to-value object at the boundary and in JSON; prints for console", async () => {
+    const result = await run(`
+      const headers = new Headers({ "X-A": "1", b: "2" })
+      console.log(headers)
+      return { headers, json: JSON.stringify({ headers }), text: String(headers), type: typeof headers, is: headers instanceof Headers }
+    `)
+    expect(result.ok && result.value).toEqual({
+      headers: { b: "2", "x-a": "1" },
+      json: '{"headers":{"b":"2","x-a":"1"}}',
+      text: "[object Headers]",
+      type: "object",
+      is: true,
+    })
+    expect(result.ok && result.logs?.[0]).toBe('Headers {"b":"2","x-a":"1"}')
+  })
+
+  test("rejects what it cannot build from, and invalid names and values, with TypeErrors the program can catch", async () => {
+    expect(
+      await value(`
+        function message(run) {
+          try { run(); return null } catch (error) { return error instanceof TypeError ? error.message : error }
+        }
+        const headers = new Headers()
+        return [
+          message(() => Headers()),
+          message(() => new Headers(null)),
+          message(() => new Headers(1)),
+          message(() => new Headers("a=1")),
+          message(() => new Headers(new Date())),
+          message(() => new Headers(() => 1)),
+          message(() => new Headers([["name"]])),
+          message(() => new Headers([["a", "b", "c"]])),
+          message(() => new Headers({ "bad name": "x" })),
+          message(() => new Headers({ name: "bad\u0000value" })),
+          message(() => headers.get("invalid\u0100")),
+          message(() => headers.has({})),
+          message(() => headers.set("a", "invalid\u0100")),
+          message(() => headers.append("a")),
+          message(() => headers.forEach()),
+          message(() => headers.forEach(1)),
+          message(() => { const get = headers.get; return get("a") }),
+        ]
+      `),
+    ).toEqual([
+      "Constructor Headers requires 'new'.",
+      "new Headers(...) expects a record of names to values, iterable [name, value] pairs, or Headers.",
+      "new Headers(...) expects a record of names to values, iterable [name, value] pairs, or Headers.",
+      "new Headers(...) expects a record of names to values, iterable [name, value] pairs, or Headers.",
+      "new Headers(...) expects a record of names to values, iterable [name, value] pairs, or Headers.",
+      "new Headers(...) expects a record of names to values, iterable [name, value] pairs, or Headers.",
+      "new Headers(...) expects iterable [name, value] pairs.",
+      "new Headers(...) expects iterable [name, value] pairs.",
+      expect.stringContaining("bad name"),
+      expect.stringContaining("invalid value"),
+      expect.stringContaining("Invalid header name"),
+      expect.stringContaining("[object Object]"),
+      expect.stringContaining("invalid value"),
+      "Headers.append requires 2 arguments.",
+      "Headers.forEach requires 1 argument.",
+      "Headers.forEach expects a function callback.",
+      "Headers.prototype.get called on incompatible receiver undefined.",
+    ])
+  })
+})
+
 describe("Map", () => {
  test("get/set/has/size with chaining", async () => {
    expect(
@@ -668,18 +816,28 @@ describe("Map", () => {
    expect((await error(`return new Map(["flat"])`)).message).toMatch(/\[key, value\] pairs/)
  })

-  test("keys/values/entries return arrays", async () => {
+  test("keys/values/entries return live iterators", async () => {
    expect(
      await value(`
      const m = new Map([["a", 1], ["b", 2]])
-      return { keys: m.keys(), values: m.values(), entries: m.entries() }
+      const keys = m.keys()
+      const first = keys.next()
+      m.set("c", 3)
+      return { first, rest: [...keys], values: [...m.values()], entries: [...m.entries()], same: [...m[Symbol.iterator]()] }
    `),
    ).toEqual({
-      keys: ["a", "b"],
-      values: [1, 2],
+      first: { value: "a", done: false },
+      rest: ["b", "c"],
+      values: [1, 2, 3],
      entries: [
        ["a", 1],
        ["b", 2],
+        ["c", 3],
+      ],
+      same: [
+        ["a", 1],
+        ["b", 2],
+        ["c", 3],
      ],
    })
  })
@@ -740,6 +898,42 @@ describe("Map", () => {
    ).toEqual({ a: 3, b: 1, c: 1 })
  })

+  test("getOrInsert and getOrInsertComputed insert only when the key is missing", async () => {
+    expect(
+      await value(`
+      const groups = new Map()
+      groups.getOrInsert("a", []).push(1)
+      groups.getOrInsert("a", []).push(2)
+      let calls = 0
+      const computed = (key) => { calls++; return key + "!" }
+      const first = groups.getOrInsertComputed("b", computed)
+      const second = groups.getOrInsertComputed("b", computed)
+      const zero = groups.getOrInsertComputed(-0, (key) => 1 / key === Infinity)
+      return [[...groups], first, second, calls, zero]
+    `),
+    ).toEqual([
+      [
+        ["a", [1, 2]],
+        ["b", "b!"],
+        [0, true],
+      ],
+      "b!",
+      "b!",
+      1,
+      true,
+    ])
+    expect(
+      await value(`
+      const m = new Map()
+      const outer = m.getOrInsertComputed("k", () => { m.set("k", "inner"); return "outer" })
+      let thrown
+      try { m.getOrInsertComputed("j", () => { throw new Error("boom") }) } catch (error) { thrown = error.message }
+      return [outer, m.get("k"), thrown, m.has("j")]
+    `),
+    ).toEqual(["outer", "outer", "boom", false])
+    expect((await error(`new Map().getOrInsertComputed("k", 5)`)).message).toContain("expects a function callback")
+  })
+
  test("maps serialize to {} at the boundary, like JSON", async () => {
    expect(await value(`return new Map([["a", 1]])`)).toEqual({})
    expect(await value(`return JSON.stringify(new Map([["a", 1]]))`)).toBe("{}")
@@ -903,7 +1097,7 @@ describe("Uint8Array", () => {
      console.log(b, new Uint8Array())
      return [String(b), b + "", +new Uint8Array([5]), Number.isNaN(Number(b)), b == "1,2", JSON.stringify(b), b.toLocaleString(), typeof b, b instanceof Uint8Array]
    `),
-    ).toEqual(["1,2", "1,2", 5, true, true, '{"0":1,"1":2}', "[object Uint8Array]", "object", true])
+    ).toEqual(["1,2", "1,2", 5, true, true, '{"0":1,"1":2}', "1,2", "object", true])
    expect((await run(`console.log(new Uint8Array([1, 2]), new Uint8Array())`)).logs).toEqual([
      "Uint8Array(2) [1,2] Uint8Array(0) []",
    ])
@@ -971,6 +1165,177 @@ describe("TextEncoder and TextDecoder", () => {
  })
 })

+describe("built-in iterators", () => {
+  test("keys/values/entries and [Symbol.iterator] step with next() and stay live", async () => {
+    expect(
+      await value(`
+        const items = ["a"]
+        const it = items.entries()
+        items.push("b")
+        const steps = [it.next(), it.next(), it.next()]
+        items.push("c")
+        return { steps, after: it.next(), same: items[Symbol.iterator] === items.values }
+      `),
+    ).toEqual({
+      steps: [{ value: [0, "a"], done: false }, { value: [1, "b"], done: false }, { done: true }],
+      after: { done: true },
+      same: true,
+    })
+    expect(
+      await value(`
+        const s = new Set([1, 2])
+        const u = new URLSearchParams("a=1&b=2")
+        const h = new Headers({ b: "2", a: "1" })
+        const bytes = new Uint8Array([7, 8])
+        return [
+          [...s.entries()], [...s[Symbol.iterator]()], s[Symbol.iterator] === s.values,
+          [...u.keys()], [...u[Symbol.iterator]()], u[Symbol.iterator] === u.entries,
+          [...h.values()], [...h[Symbol.iterator]()], h[Symbol.iterator] === h.entries,
+          [...bytes.entries()], [...bytes[Symbol.iterator]()], bytes[Symbol.iterator] === bytes.values,
+          [..."ab"[Symbol.iterator]()],
+        ]
+      `),
+    ).toEqual([
+      [
+        [1, 1],
+        [2, 2],
+      ],
+      [1, 2],
+      true,
+      ["a", "b"],
+      [
+        ["a", "1"],
+        ["b", "2"],
+      ],
+      true,
+      ["1", "2"],
+      [
+        ["a", "1"],
+        ["b", "2"],
+      ],
+      true,
+      [
+        [0, 7],
+        [1, 8],
+      ],
+      [7, 8],
+      true,
+      ["a", "b"],
+    ])
+  })
+
+  test("iterators are consumed once by every iteration site", async () => {
+    expect(
+      await value(`
+        const it = [1, 2, 3, 4].values()
+        const picked = []
+        for (const item of it) { picked.push(item); if (item === 2) break }
+        const [third] = it
+        return { picked, third, rest: [...it], spent: Array.from(it), again: it[Symbol.iterator]() === it }
+      `),
+    ).toEqual({ picked: [1, 2], third: 3, rest: [4], spent: [], again: true })
+    expect(
+      await value(`
+        const m = new Map([["a", 1], ["b", 2]])
+        return [
+          Object.fromEntries(m.entries()), Array.from(m.keys(), (k) => k + "!"), new Set(m.values()).size,
+          await Promise.all([Promise.resolve(1), 2].values()),
+        ]
+      `),
+    ).toEqual([{ a: 1, b: 2 }, ["a!", "b!"], 2, [1, 2]])
+    expect(await value(`let s = 0; for await (const v of [Promise.resolve(1), 2].values()) s += v; return s`)).toBe(3)
+    expect(
+      await value(`return new Set([1, 2]).union({ size: 1, has: () => false, keys: () => new Set([3]).keys() })`),
+    ).toEqual([1, 2, 3])
+  })
+
+  test("iterators are opaque references", async () => {
+    expect(await value(`return [1].keys()`)).toEqual({})
+    expect(await value(`return JSON.stringify({ it: [1].keys() })`)).toBe('{"it":{}}')
+    expect(await value(`return [typeof [1].keys(), Array.isArray([1].keys()), Object.keys([1].keys())]`)).toEqual([
+      "object",
+      false,
+      [],
+    ])
+    const logged = await run(`console.log([1].keys()); return null`)
+    expect(logged.logs?.[0]).toBe("[opaque reference]")
+    expect((await error(`return [1].keys() + ""`)).message).toContain("Binary operators require data values")
+    expect((await error(`return [1].keys().next.call({})`)).message).toContain("is not a function")
+    expect((await error(`const it = [1].keys(); const next = it.next; return next()`)).message).toContain(
+      "Iterator.prototype.next called on incompatible receiver undefined",
+    )
+  })
+})
+
+describe("Object.prototype.toString", () => {
+  test("reports the built-in kind it is inherited by, as JS does through Symbol.toStringTag", async () => {
+    expect(
+      await value(`
+      return [
+        new Map().toString(), new Set().toString(), new Headers().toString(), Promise.resolve(1).toString(),
+        [1].values().toString(), ({}).toString(), String(new Map()), String(Promise.resolve(1)),
+        \`\${new Set([1])}\`, [new Map()] + "", new Map() == "[object Map]",
+      ]
+    `),
+    ).toEqual([
+      "[object Map]",
+      "[object Set]",
+      "[object Headers]",
+      "[object Promise]",
+      "[object Iterator]",
+      "[object Object]",
+      "[object Map]",
+      "[object Promise]",
+      "[object Set]",
+      "[object Map]",
+      true,
+    ])
+  })
+})
+
+describe("toLocaleString", () => {
+  test("numbers and dates format as en-US in UTC; everything else falls back to toString", async () => {
+    expect(
+      await value(`
+      return [
+        (1234567.891).toLocaleString(), new Date(0).toLocaleString(), new Date(0).toLocaleDateString(),
+        new Date(0).toLocaleTimeString(), "a".toLocaleString(), true.toLocaleString(), ({}).toLocaleString(),
+        ({ toString: () => "custom" }).toLocaleString(), new Uint8Array([1, 2]).toLocaleString(),
+      ]
+    `),
+    ).toEqual([
+      "1,234,567.891",
+      "1/1/1970, 12:00:00 AM",
+      "1/1/1970",
+      "12:00:00 AM",
+      "a",
+      "true",
+      "[object Object]",
+      "custom",
+      "1,2",
+    ])
+  })
+
+  test("arrays join each element's toLocaleString, skipping holes and nullish elements", async () => {
+    expect(
+      await value(`
+      let calls = 0
+      const item = { toLocaleString() { calls++; return "o" } }
+      return [[1234.5, "x", null, undefined, item, new Date(0)].toLocaleString(), [, item, , item].toLocaleString(), calls]
+    `),
+    ).toEqual(["1,234.5,x,,,o,1/1/1970, 12:00:00 AM", ",o,,o", 3])
+    expect((await error(`const f = ({}).toLocaleString; f()`)).message).toContain(
+      "Object.prototype.toLocaleString called on null or undefined",
+    )
+  })
+
+  test("toLocaleLowerCase and toLocaleUpperCase ignore the locale argument", async () => {
+    expect(
+      await value(`return ["ABC".toLocaleLowerCase("tr"), "abc".toLocaleUpperCase(), "İ".toLocaleLowerCase()]`),
+    ).toEqual(["abc", "ABC", "i̇"])
+  })
+})
+
 describe("stdlib integration", () => {
  test("constructor follows own keys, shadowing, writes, and new", async () => {
    expect(
@@ -9,7 +9,7 @@ import type { Interpreter } from "../../src/interpreter/interpreter.js"
 import { Throw } from "../../src/interpreter/model.js"
 import { createErrorValue } from "../../src/interpreter/intrinsics.js"
 import { constructor, fn, methods } from "../../src/interpreter/native.js"
-import { Callable, define, get, hidden, Arr, Fn, Obj } from "../../src/interpreter/objects.js"
+import { Callable, define, get, hidden, Arr, Fn, Obj, type Value } from "../../src/interpreter/objects.js"
 import { ToolRuntime } from "../../src/tool-runtime.js"

 export const root = import.meta.dir
@@ -64,10 +64,7 @@ export const run = async (file: string): Promise<Outcome> => {
  return { status: "pass" }
 }

-const harness = <R>(
-  ctx: Interpreter<R>,
-  onDone: (error: unknown) => void,
-): ReadonlyArray<readonly [string, unknown]> => {
+const harness = <R>(ctx: Interpreter<R>, onDone: (error: Value) => void): ReadonlyArray<readonly [string, Value]> => {
  const builtins = ctx.builtins
  const test262Prototype = new Obj(builtins.Object)
  define(test262Prototype, "name", "Test262Error", hidden)
@@ -90,7 +87,7 @@ const harness = <R>(
  methods(builtins, compareArray, [["format", 1, (_, args) => show(args[0])]])
  const assert = fn<R>(builtins, "assert", 2, (_, args) =>
    args[0] === true
-      ? Effect.void
+      ? Effect.undefined
      : fail(args[1] === undefined ? `Expected true but got ${show(args[0])}` : String(args[1])),
  )
  methods(builtins, assert, [
@@ -99,7 +96,7 @@ const harness = <R>(
      3,
      (_, args) =>
        Object.is(args[0], args[1])
-          ? Effect.void
+          ? Effect.undefined
          : fail(`${prefix(args[2])}Expected SameValue(«${show(args[0])}», «${show(args[1])}») to be true`),
    ],
    [
@@ -108,14 +105,14 @@ const harness = <R>(
      (_, args) =>
        Object.is(args[0], args[1])
          ? fail(`${prefix(args[2])}Expected SameValue(«${show(args[0])}», «${show(args[1])}») to be false`)
-          : Effect.void,
+          : Effect.undefined,
    ],
    [
      "compareArray",
      3,
      (_, args) =>
        compare(args[0], args[1])
-          ? Effect.void
+          ? Effect.undefined
          : fail(
              `Actual ${show(args[0])} and expected ${show(args[1])} should have the same contents. ${prefix(args[2])}`,
            ),
@@ -132,7 +129,7 @@ const harness = <R>(
              const thrown = materialize(ctx, Cause.squash(cause))
              if (!(thrown instanceof Obj)) return fail(`${prefix(args[2])}Thrown value was not an object!`)
              const actual = get(thrown, "constructor")
-              if (actual === args[0]) return Effect.void
+              if (actual === args[0]) return Effect.undefined
              return fail(`${prefix(args[2])}Expected a ${expected} but got a ${show(actual)}`)
            },
            onSuccess: () =>
@@ -146,7 +143,13 @@ const harness = <R>(
    ["assert", assert],
    ["compareArray", compareArray],
    ["Test262Error", test262Error],
-    ["$DONE", fn<R>(builtins, "$DONE", 1, (_, args) => onDone(args[0]))],
+    [
+      "$DONE",
+      fn<R>(builtins, "$DONE", 1, (_, args) => {
+        onDone(args[0])
+        return undefined
+      }),
+    ],
    [
      "$DONOTEVALUATE",
      fn<R>(builtins, "$DONOTEVALUATE", 0, () =>
--- a/Show More
+++ b/Show More
Author	SHA1	Message	Date
Aiden Cline	fd7d831d21	refactor(codemode): type program values as Value	2026-09-20 21:06:11 -05:00
Aiden Cline	1233a112d2	refactor(codemode): let each built-in object answer for itself	2026-09-20 21:05:45 -05:00
Aiden Cline	cbdd1f66da	fix(codemode): locate failures in the submitted source (#50197 )	2026-09-20 20:47:54 -05:00
Luke Parker	788eb0fa29	fix(cli): report fatal startup causes on stderr (#50240 )	2026-09-20 22:57:20 +00:00
opencode-agent[bot]andkitlangton	58fcad77a8	feat(tui): copy session ID from tab menu (#50181 ) Co-authored-by: kitlangton <7587245+kitlangton@users.noreply.github.com>	2026-09-20 19:15:37 +00:00
Aiden Cline	c555559ac1	refactor(plugin): name tool execution context (#50195 )	2026-09-20 11:36:19 -05:00
Aiden Cline	e3a3fa7108	fix(plugin): forward Promise tool cancellation (#50190 )	2026-09-20 11:22:49 -05:00
opencode-agent[bot]	6238af397e	chore(core): refresh bundled models.dev snapshot	2026-09-20 16:17:29 +00:00
Aiden Cline	7ffd75faf6	fix(core): restore anthropic budget variants (#50182 )	2026-09-20 10:50:21 -05:00
opencode-agent[bot]	1f8ab95695	chore(core): refresh bundled models.dev snapshot	2026-09-20 15:37:06 +00:00
Aiden Cline	62dc1f7696	feat(codemode): add toLocaleString, Error.isError, and Map.getOrInsert (#50098 )	2026-09-20 10:23:23 -05:00
opencode-agent[bot]	66f10ab7bf	chore(core): refresh bundled models.dev snapshot	2026-09-20 14:37:06 +00:00
opencode-agent[bot]	1ca8f63a79	chore(core): refresh bundled models.dev snapshot	2026-09-20 13:36:51 +00:00
opencode-agent[bot]	03bcdd580d	chore(core): refresh bundled models.dev snapshot	2026-09-20 12:43:39 +00:00
opencode-agent[bot]	cc502f7e5f	chore(core): refresh bundled models.dev snapshot	2026-09-20 11:37:37 +00:00
opencode-agent[bot]	64ce8771c0	chore(core): refresh bundled models.dev snapshot	2026-09-20 10:37:01 +00:00
opencode-agent[bot]	702a73d91a	chore(core): refresh bundled models.dev snapshot	2026-09-20 09:37:50 +00:00
opencode	991b727eb8	sync release versions for v2.0.11	2026-09-20 08:57:41 +00:00
opencode-agent[bot]	ba342ce227	chore(core): refresh bundled models.dev snapshot	2026-09-20 08:42:13 +00:00
David Hill	1464545665	fix(app): center timeline beside summary (#49620 )	2026-09-20 18:06:32 +10:00
David Hill	fecacc9e68	fix(app): match vertical nav tab states (#49619 )	2026-09-20 18:03:49 +10:00
David HillandLukeParkerDev	1f73b4806b	fix(desktop): polish browser panel states and navigation (#49432 ) Co-authored-by: LukeParkerDev <10430890+Hona@users.noreply.github.com>	2026-09-20 07:54:25 +00:00
opencode-agent[bot]	da2ce02596	chore(core): refresh bundled models.dev snapshot	2026-09-20 07:38:48 +00:00
opencode-agent[bot]	25f35dcfb8	chore(core): refresh bundled models.dev snapshot	2026-09-20 06:49:40 +00:00
Luke Parker	717f81ce08	chore(desktop): attribute renderer CPU profiles to source files (#50114 )	2026-09-20 16:30:35 +10:00
Luke Parker	5fdfcc7a80	perf(desktop): hand the window its persisted stores before the first render (#50113 )	2026-09-20 16:29:02 +10:00
Luke Parker	0530c8e512	perf(desktop): talk to the main process without the Effect runtime in the renderer (#50112 )	2026-09-20 16:26:08 +10:00
Luke Parker	1d8cf4564b	perf(desktop): move startup work that the first window does not need off its path (#50111 )	2026-09-20 16:23:37 +10:00
Luke Parker	7e88f6bb18	perf(desktop): bundle the renderer's initial module graph as one chunk (#50110 )	2026-09-20 16:19:28 +10:00
Luke Parker	af592fb779	perf(desktop): serve the renderer's first assets before evaluating the main bundle (#50109 )	2026-09-20 16:18:50 +10:00
Luke Parker	7fc3f68007	perf(desktop): boot the renderer alongside the main bundle (#50108 )	2026-09-20 16:15:58 +10:00
opencode-agent[bot]	cdcbb0047e	chore(core): refresh bundled models.dev snapshot	2026-09-20 05:38:29 +00:00
opencode-agent[bot]	a1956a7522	chore(core): refresh bundled models.dev snapshot	2026-09-20 04:42:05 +00:00
opencode-agent[bot]	55bc7fd403	chore(core): refresh bundled models.dev snapshot	2026-09-20 03:43:32 +00:00
opencode-agent[bot]	3049b1e684	chore(core): refresh bundled models.dev snapshot	2026-09-20 02:45:23 +00:00
opencode-agent[bot]	1f36a7aff8	chore(core): refresh bundled models.dev snapshot	2026-09-20 01:31:11 +00:00
Aiden Cline	eb0e26b974	feat(codemode): return live iterators from keys, values, and entries (#50061 )	2026-09-19 18:46:35 -05:00
opencode-agent[bot]	6f2b0e7833	chore(core): refresh bundled models.dev snapshot	2026-09-19 23:38:19 +00:00
opencode-agent[bot]	f153255942	chore(core): refresh bundled models.dev snapshot	2026-09-19 22:37:11 +00:00
opencode-agent[bot]	fef2fad76f	chore(core): refresh bundled models.dev snapshot	2026-09-19 22:15:20 +00:00
Aiden Cline	f30d06ea34	fix(core): pin the session to http after repeated websocket stream losses (#50031 )	2026-09-19 16:45:54 -05:00
Kit Langton	dfa44e94e8	fix(tui): use focused action token for question form border (#50037 )	2026-09-19 19:07:10 +00:00
Aiden Cline	b81e10a461	fix(core): re-read models.dev catalog after subscribing to Refreshed (#50012 )	2026-09-19 13:31:38 -05:00
Aiden Cline	65c93b69ed	fix(ai): never fail decoding on Responses error frames (#49402 )	2026-09-19 13:27:05 -05:00
Aiden Cline	b073b052d3	fix(ai): remove bounded websocket inbound queues (#50026 )	2026-09-19 13:26:37 -05:00
Aiden Cline	728b2b6052	fix(core): honor session permissions in skill and MCP discovery (#50015 )	2026-09-19 12:59:09 -05:00
Aiden Cline	cc3ce20ab4	feat(codemode): add the Headers built-in (#49280 )	2026-09-19 12:35:14 -05:00
Aiden Cline	4ad5001be2	chore(core): refresh bundled models.dev snapshot (#50009 )	2026-09-19 12:24:10 -05:00
Matt SimpsonandAiden Cline	14b3c2ea4b	feat(cli): support Vite+ installations (#49624 ) Co-authored-by: Aiden Cline <63023139+rekram1-node@users.noreply.github.com>	2026-09-19 12:16:47 -05:00
opencode-agent[bot]andrekram1-node	558bd54c9b	fix(tui): use muted autocomplete label text (#50008 ) Co-authored-by: rekram1-node <rekram1-node@users.noreply.github.com>	2026-09-19 12:16:41 -05:00
Filip	7e70f7e1ab	feat(tui): label mention autocomplete options (#48551 )	2026-09-19 16:05:03 +02:00
opencode	cb6d95b7ef	sync release versions for v2.0.10	2026-09-19 13:40:59 +00:00
opencode-agent[bot]andBrendonovich	7020944359	fix(app): restore mobile tab interactions (#49964 ) Co-authored-by: Brendonovich <14191578+Brendonovich@users.noreply.github.com>	2026-09-19 21:00:45 +08:00
Shoubhit Dash	4b00dd2713	feat(tui): session-scoped plugin toasts (#49962 )	2026-09-19 18:24:38 +05:30
Chris YangandBrendan Allan	b447627f5f	fix(app): keep shortcuts search field focused while typing (#49779 ) Co-authored-by: Brendan Allan <14191578+Brendonovich@users.noreply.github.com>	2026-09-19 20:43:58 +08:00
opencode-agent[bot]andBrendonovich	5848ee0d24	fix(app): restore attachment classification (#49932 ) Co-authored-by: Brendonovich <14191578+Brendonovich@users.noreply.github.com>	2026-09-19 09:13:29 +00:00
Dax Raad	839aa25c3e	feat(cli): publish Homebrew formula	2026-09-19 04:37:36 -04:00
Dax Raad	c42f1c9232	Revert "feat(web): add v2 announcement banner to legacy docs" This reverts commit `7b7a67080e`.	2026-09-19 03:24:40 -04:00
Kit Langton	417f6d234d	fix(tui): restore running and unread status hue aliases (#49907 )	2026-09-19 02:05:53 -04:00
opencode	45a13af0ee	sync release versions for v2.0.9	2026-09-19 05:13:01 +00:00
Luke Parker	e50d845451	fix(desktop): run WSL commands with --exec so inline scripts are not pre-expanded (#49902 )	2026-09-19 14:36:04 +10:00
Kit Langton	56816621f8	fix(tui): restore foreground hue step for tab status colors (#49899 )	2026-09-19 04:33:23 +00:00
Luke Parker	7125f5f8b5	chore(desktop): measure the startup bench from the screen (#49894 )	2026-09-19 14:06:58 +10:00
opencode-agent[bot]	01a6ed8d97	chore: update nix node_modules hashes	2026-09-19 02:49:44 +00:00
opencode-agent[bot]rekram1-node Aiden Cline	004583d598	refactor(codemode): remove TypeScript stripping (#49870 ) Co-authored-by: rekram1-node <rekram1-node@users.noreply.github.com> Co-authored-by: Aiden Cline <aidenpcline@gmail.com>	2026-09-18 21:24:11 -05:00
Aiden Cline	cbd911368e	refactor(schema): separate provider and model settings (#49850 )	2026-09-18 21:20:08 -05:00
opencode-agent[bot]	8bfb247854	chore: update nix node_modules hashes	2026-09-19 02:20:04 +00:00
Luke Parker	dd71cdbd84	fix(app): stop retaining failed sends in history and oversized toast text (#49717 )	2026-09-19 12:00:55 +10:00
Luke Parker	1c90e8f01c	perf(app): drop luxon for the three date operations that used it (#49876 )	2026-09-19 12:00:32 +10:00
Luke Parker	9843d13c29	chore(desktop): record startup marks for the benchmark (#49872 )	2026-09-19 12:00:03 +10:00
Luke Parker	871db0025e	fix(browser): describe tabs.open focus as an explicit opt-out (#49877 )	2026-09-19 11:55:49 +10:00
Dax Raad	7b7a67080e	feat(web): add v2 announcement banner to legacy docs	2026-09-18 21:35:13 -04:00
Aiden Cline	3361953fe1	fix(core): explain user-invoked skills in skill guidance (#49871 )	2026-09-18 20:32:36 -05:00
opencode-agent[bot]andrekram1-node	e9201ce933	fix(core): retain console config after refresh errors (#49873 ) Co-authored-by: rekram1-node <rekram1-node@users.noreply.github.com>	2026-09-18 20:22:23 -05:00
Dax Raad	b38d72e174	docs: link v1 docs from header	2026-09-18 20:54:48 -04:00
Luke Parker	e1e2efe8ec	perf(desktop): show the first window the moment Electron is ready (#49869 )	2026-09-19 10:41:27 +10:00
Luke Parker	c2b171d7c4	perf(client): poll for a starting service every 25 ms (#49780 )	2026-09-19 10:40:32 +10:00
Luke Parker	c3bf8864b9	perf(ui): let the resize observer take the first scrollbar measurement (#49778 )	2026-09-19 10:38:33 +10:00
Luke Parker	3693f56374	perf(desktop): enable the V8 code cache for the renderer scheme (#49767 )	2026-09-19 10:35:07 +10:00
Luke Parker	971f4e558e	perf(desktop): load node-pty when an interactive WSL install starts (#49789 )	2026-09-19 10:34:44 +10:00
Luke Parker	dd95e3f2ed	perf(desktop): collect orphaned draft blobs after the window is up (#49797 )	2026-09-19 10:34:25 +10:00
Luke Parker	dfde4628e3	perf(desktop): only persist the background colour when it changes (#49770 )	2026-09-19 10:34:04 +10:00
Luke Parker	e755fce13d	perf(desktop): leave declarations and source maps out of the asar (#49772 )	2026-09-19 10:33:48 +10:00
Luke Parker	5b565e8923	perf(desktop): create windows before the background service connects (#49763 )	2026-09-19 10:33:39 +10:00
Kit Langton	ec8d95f1f2	fix(simulation): include images in UI captures (#49868 )	2026-09-18 17:21:44 -07:00
opencode-agent[bot]	ea52d18ec5	chore: update nix node_modules hashes	2026-09-18 23:57:47 +00:00
Aiden Clineandrekram1-node	0f9504d6c5	feat(plugin): add list to the tool domain (#49838 ) Co-authored-by: rekram1-node <rekram1-node@users.noreply.github.com>	2026-09-18 18:51:37 -05:00
Luke Parker	f6353a48b5	perf(desktop): replace electron-store with a plain JSON settings store (#49791 )	2026-09-19 09:41:44 +10:00
Luke Parker	4facc03371	perf(desktop): remember window bounds without electron-window-state (#49792 )	2026-09-19 09:41:15 +10:00
Luke Parker	485a027c1a	perf(desktop): load the browser pane on first use (#49774 )	2026-09-19 09:39:36 +10:00
Luke Parker	988a66ca4f	perf(desktop): ship the bundled CLI version instead of spawning for it (#49762 )	2026-09-19 09:36:55 +10:00
Luke Parker	98c6b41573	chore(desktop): add a packaged startup benchmark (#49758 )	2026-09-19 09:23:09 +10:00
opencode-agent[bot]andthdxr	4ee9bf0213	revert(core): remove autonomous goal command (#49866 ) Co-authored-by: thdxr <826656+thdxr@users.noreply.github.com>	2026-09-18 23:14:36 +00:00
James Long	681338c533	refactor(theme): detect theme format by fields (#49853 )	2026-09-18 17:19:21 -04:00
Dax	5464aa4a74	feat(core): add autonomous goal command (#45379 )	2026-09-18 20:59:08 +00:00
James Long	36083c9520	docs(www): document theme format and workflow (#49855 )	2026-09-18 16:46:32 -04:00
James Long	168aba6183	feat(theme): register native V2 opencode theme (#49846 )	2026-09-18 16:33:59 -04:00
Kit Langton	ec19dc09c7	fix(sdk): support Node package imports (#49810 )	2026-09-18 13:10:59 -07:00
Aiden Cline	fca4701688	fix(ai): allow future Anthropic option values (#49835 )	2026-09-18 14:24:11 -05:00
James Long	c720ca20ed	refactor(theme): rename default tokens to base (#49837 )	2026-09-18 15:20:15 -04:00
James Long	dae1e8abbd	docs(www): finalize background color (#49203 )	2026-09-18 15:07:49 -04:00
James Long	ffe4d1522c	refactor(theme): derive V1 hue angles from swatches (#49839 )	2026-09-18 15:00:09 -04:00
James Long	b1860465cd	refactor(theme): split base and mode overrides (#49826 )	2026-09-18 14:48:27 -04:00
CestercianandAiden Cline	cab11795e5	fix(tui): pass markdown renderer into /btw answer dialog (#49804 ) Co-authored-by: Aiden Cline <63023139+rekram1-node@users.noreply.github.com>	2026-09-18 13:32:11 -05:00
James Long	810e79a6d4	refactor(theme): align hue direction with mode (#49820 )	2026-09-18 13:29:19 -04:00