fix(core): keep shell preview config out of session

packages/core/src/session.ts

@@ -48,6 +48,7 @@ import { Skill } from "./skill.js"
 import { Job } from "./job.js"
 import { Command } from "./command.js"
 import { Shell } from "./shell.js"
+import { ShellOutput } from "./shell/output.js"
 import { Global } from "@opencode-ai/util/global"
 import { Shell as ShellSchema } from "@opencode-ai/schema/shell"
 import { KeyedMutex } from "./effect/keyed-mutex.js"
@@ -694,9 +695,9 @@ const layer = Layer.effect(
                 ),
               )
               const output = terminal.retained
-                ? yield* shell
-                    .output(started.id, { limit: SHELL_MAX_CAPTURE_BYTES })
-                    .pipe(Effect.catchTag("Shell.NotFoundError", () => Effect.succeed(missingShellOutput())))
+                ? yield* ShellOutput.preview(started, shell).pipe(
+                    Effect.catchTag("Shell.NotFoundError", () => Effect.succeed(missingShellOutput())),
+                  )
                 : missingShellOutput()
               return { shell: terminal.info, output }
             }).pipe(Effect.provide(locations.get(session.location)))
@@ -1120,9 +1121,6 @@ function positiveInt(value: string | null) {
   return Number.isInteger(parsed) && parsed > 0 ? parsed : undefined
 }
 
-// Mirrors the shell tool's in-memory preview safety limit.
-const SHELL_MAX_CAPTURE_BYTES = 1024 * 1024
-
 export const node = makeGlobalNode({
   service: Service,
   layer: layer.pipe(Layer.orDie),

packages/core/src/shell/output.ts

@@ -0,0 +1,25 @@
+export * as ShellOutput from "./output.js"
+
+import { Effect } from "effect"
+import type { Info } from "@opencode-ai/schema/shell"
+import { Config } from "../config.js"
+import { Shell } from "../shell.js"
+import { ToolOutput } from "../tool-output.js"
+
+export const preview = Effect.fn("ShellOutput.preview")(function* (info: Info, shell: Shell.Interface) {
+  const config = yield* Config.Service
+  const configured = Config.latest(yield* config.entries(), "tool_output")
+  const maxLines = configured?.max_lines ?? ToolOutput.MAX_LINES
+  const maxBytes = configured?.max_bytes ?? ToolOutput.MAX_BYTES
+  const latest = yield* shell.output(info.id, { cursor: Number.MAX_SAFE_INTEGER })
+  const page = yield* shell.output(info.id, {
+    cursor: Math.max(0, latest.size - maxBytes),
+    limit: maxBytes,
+  })
+  const lines = page.output.split("\n")
+  if (page.output.endsWith("\n")) lines.pop()
+  const truncated = latest.size > maxBytes || lines.length > maxLines
+  const output = lines.length > maxLines ? lines.slice(-maxLines).join("\n") : page.output
+  const notice = truncated ? `\n\n[output truncated; full output saved to: ${info.file}]` : ""
+  return { ...page, output: `${output || "(no output)"}${notice}`, truncated }
+})

packages/core/src/tool/plugin/shell.ts

@@ -12,9 +12,9 @@ import { PluginRuntime } from "../../plugin/runtime.js"
 import { NonNegativeInt } from "../../schema.js"
 import { SessionSchema } from "../../session/schema.js"
 import { Shell } from "../../shell.js"
+import { ShellOutput } from "../../shell/output.js"
 import { ShellParse } from "../../shell/parse.js"
 import { ShellSelect } from "../../shell/select.js"
-import { ToolOutput } from "../../tool-output.js"
 
 export const name = "shell"
 export const DEFAULT_TIMEOUT_MS = 2 * 60 * 1_000
@@ -239,29 +239,11 @@ export const Plugin = {
               )
               yield* context.progress({ shellID: info.id })
 
-              const captureShell = Effect.fnUntraced(function* () {
-                const configured = Config.latest(yield* config.entries(), "tool_output")
-                const maxLines = configured?.max_lines ?? ToolOutput.MAX_LINES
-                const maxBytes = configured?.max_bytes ?? ToolOutput.MAX_BYTES
-                const latest = yield* shell.output(info.id, { cursor: Number.MAX_SAFE_INTEGER })
-                const page = yield* shell.output(info.id, {
-                  cursor: Math.max(0, latest.size - maxBytes),
-                  limit: maxBytes,
-                })
-                const lines = page.output.split("\n")
-                if (page.output.endsWith("\n")) lines.pop()
-                const truncated = latest.size > maxBytes || lines.length > maxLines
-                const output = lines.length > maxLines ? lines.slice(-maxLines).join("\n") : page.output
-                const notice = truncated ? `\n\n[output truncated; full output saved to: ${info.file}]` : ""
-                return {
-                  output: `${output || "(no output)"}${notice}`,
-                  truncated,
-                }
-              })
-
               const settleShell = Effect.fnUntraced(function* () {
                 const final = yield* shell.wait(info.id)
-                const capture = yield* captureShell()
+                const capture = yield* ShellOutput.preview(info, shell).pipe(
+                  Effect.provideService(Config.Service, config),
+                )
 
                 // `exit` is optionalKey in the Output schema; a present-but-undefined key
                 // fails output encoding, so omit it when the process has no exit code.

packages/core/test/session-create.test.ts

@@ -30,6 +30,7 @@ import { SessionEvent } from "@opencode-ai/core/session/event"
 import { SessionTable } from "@opencode-ai/core/session/sql"
 import { SessionStore } from "@opencode-ai/core/session/store"
 import { SessionTransfer } from "@opencode-ai/core/session/transfer"
+import { ToolOutput } from "@opencode-ai/core/tool-output"
 import { Workspace } from "@opencode-ai/core/workspace"
 import { testEffect } from "./lib/effect"
 import { globalProjectLayer } from "./lib/project"
@@ -888,6 +889,61 @@ describe("Session.create", () => {
     ),
   )
 
+  it.live("truncates direct shell output using the shared shell preview policy", () =>
+    withTmp((directory) =>
+      Effect.gen(function* () {
+        const session = yield* Session.Service
+        const created = yield* session.create({
+          location: Location.Ref.make({ directory: AbsolutePath.make(directory) }),
+        })
+        const bytes = ToolOutput.MAX_BYTES + 1024
+        const command =
+          process.platform === "win32"
+            ? `[Console]::Out.Write('output-start' + ('x' * ${bytes}) + 'output-end')`
+            : `printf output-start; head -c ${bytes} /dev/zero | tr '\\0' 'x'; printf output-end`
+
+        yield* session.shell({ sessionID: created.id, command })
+
+        const messages = yield* session.messages({ sessionID: created.id, order: "asc" })
+        const shell = messages.find((message): message is SessionMessage.Shell => message.type === "shell")
+        expect(shell?.output?.truncated).toBe(true)
+        expect(shell?.output?.output).not.toContain("output-start")
+        expect(shell?.output?.output).toContain("output-end")
+        expect(shell?.output?.output).toContain("output truncated; full output saved to:")
+      }),
+    ),
+  )
+
+  it.live("applies configured output limits to direct shell commands", () =>
+    withTmp((directory) =>
+      Effect.gen(function* () {
+        yield* Effect.promise(() =>
+          Bun.write(
+            path.join(directory, "opencode.json"),
+            JSON.stringify({ tool_output: { max_lines: 2, max_bytes: 1_000 } }),
+          ),
+        )
+        const session = yield* Session.Service
+        const created = yield* session.create({
+          location: Location.Ref.make({ directory: AbsolutePath.make(directory) }),
+        })
+        const command =
+          process.platform === "win32"
+            ? "[Console]::Out.Write('one' + [Environment]::NewLine + 'two' + [Environment]::NewLine + 'three')"
+            : "printf 'one\\ntwo\\nthree'"
+
+        yield* session.shell({ sessionID: created.id, command })
+
+        const messages = yield* session.messages({ sessionID: created.id, order: "asc" })
+        const shell = messages.find((message): message is SessionMessage.Shell => message.type === "shell")
+        expect(shell?.output?.truncated).toBe(true)
+        expect(shell?.output?.output).not.toContain("one")
+        expect(shell?.output?.output.replaceAll("\r\n", "\n")).toStartWith("two\nthree")
+        expect(shell?.output?.output).toContain("output truncated; full output saved to:")
+      }),
+    ),
+  )
+
   it.live("still emits shell ended for a failing command", () =>
     withTmp((directory) =>
       Effect.gen(function* () {