From 76f205d260f5b8680ed0103b700ca5cea45f5121 Mon Sep 17 00:00:00 2001
From: Kit Langton <kit.langton@gmail.com>
Date: Tue, 14 Jul 2026 11:35:12 -0400
Subject: [PATCH] fix(tui): restore compaction model marker

---
 .../client/src/promise/generated/types.ts     | 25 ++++++++++---------
 packages/core/src/session/compaction.ts       |  5 ++++
 packages/core/src/session/message-updater.ts  |  2 ++
 packages/core/src/session/runner/llm.ts       |  6 ++---
 packages/core/test/session-compaction.test.ts |  8 +++++-
 packages/schema/src/session-event.ts          |  1 +
 packages/schema/src/session-message.ts        |  1 +
 packages/schema/test/session-message.test.ts  | 21 ++++++++++++++++
 packages/tui/src/context/data.tsx             |  2 ++
 packages/tui/src/routes/session/index.tsx     | 16 +++++++++++-
 packages/tui/src/util/model.ts                | 12 +++++++++
 packages/tui/test/cli/tui/data.test.tsx       |  9 ++++++-
 packages/tui/test/util/model.test.ts          | 16 +++++++++++-
 13 files changed, 105 insertions(+), 19 deletions(-)
 create mode 100644 packages/schema/test/session-message.test.ts

diff --git a/packages/client/src/promise/generated/types.ts b/packages/client/src/promise/generated/types.ts
index 255beaa1bb..a4b1bd5ed8 100644
--- a/packages/client/src/promise/generated/types.ts
+++ b/packages/client/src/promise/generated/types.ts
@@ -117,17 +117,6 @@ export type SessionMessageCompactionRunning = {
   recent: string
 }
 
-export type SessionMessageCompactionCompleted = {
-  type: "compaction"
-  id: string
-  metadata?: { [x: string]: JsonValue }
-  time: { created: number }
-  status: "completed"
-  reason: "auto" | "manual"
-  summary: string
-  recent: string
-}
-
 export type InstructionEntryKey = string
 
 export type SessionPendingSyntheticData1 = { text: string; description?: string; metadata?: { [x: string]: any } }
@@ -507,6 +496,18 @@ export type SessionMessageModelSelected = {
   previous?: ModelRef
 }
 
+export type SessionMessageCompactionCompleted = {
+  type: "compaction"
+  id: string
+  metadata?: { [x: string]: JsonValue }
+  time: { created: number }
+  status: "completed"
+  reason: "auto" | "manual"
+  model?: ModelRef
+  summary: string
+  recent: string
+}
+
 export type CommandInfo = {
   name: string
   template: string
@@ -749,7 +750,7 @@ export type SessionCompactionEnded = {
   type: "session.compaction.ended"
   durable: { aggregateID: string; seq: number; version: 1 }
   location?: LocationRef
-  data: { sessionID: string; reason: "auto" | "manual"; text: string; recent: string }
+  data: { sessionID: string; reason: "auto" | "manual"; model?: ModelRef; text: string; recent: string }
 }
 
 export type SessionRevertCleared = {
diff --git a/packages/core/src/session/compaction.ts b/packages/core/src/session/compaction.ts
index 19ba3c9053..83106d3ec4 100644
--- a/packages/core/src/session/compaction.ts
+++ b/packages/core/src/session/compaction.ts
@@ -69,6 +69,7 @@ export type AutoInput = {
   readonly sessionID: SessionSchema.ID
   readonly messages: readonly SessionMessage.Info[]
   readonly model: Model
+  readonly ref: SessionMessage.Assistant["model"]
 }
 
 export type ManualInput = {
@@ -80,6 +81,7 @@ export type ManualInput = {
 type Plan = {
   readonly sessionID: SessionSchema.ID
   readonly model: Model
+  readonly ref: SessionMessage.Assistant["model"]
   readonly reason: SessionMessage.Compaction["reason"]
   readonly prompt: string
   readonly recent: string
@@ -291,6 +293,7 @@ const make = (dependencies: Dependencies) => {
     yield* dependencies.events.publish(SessionEvent.Compaction.Ended, {
       sessionID: plan.sessionID,
       reason: plan.reason,
+      model: plan.ref,
       text: summary,
       recent: plan.recent,
     })
@@ -302,6 +305,7 @@ const make = (dependencies: Dependencies) => {
       return yield* execute({
         sessionID: input.sessionID,
         model: input.model,
+        ref: input.ref,
         reason: "auto",
         ...content,
       })
@@ -350,6 +354,7 @@ const make = (dependencies: Dependencies) => {
     return yield* execute({
       sessionID: input.session.id,
       model: resolved.model,
+      ref: resolved.ref,
       reason: "manual",
       inputID: input.inputID,
       ...content,
diff --git a/packages/core/src/session/message-updater.ts b/packages/core/src/session/message-updater.ts
index 2f7f1d3d12..ba53c66c1c 100644
--- a/packages/core/src/session/message-updater.ts
+++ b/packages/core/src/session/message-updater.ts
@@ -470,6 +470,7 @@ export function update(adapter: Adapter, event: SessionEvent.Event) {
               ...current,
               status: "completed",
               reason: event.data.reason,
+              model: event.data.model,
               summary: event.data.text,
               recent: event.data.recent,
             })
@@ -482,6 +483,7 @@ export function update(adapter: Adapter, event: SessionEvent.Event) {
               status: "completed",
               metadata: event.metadata,
               reason: event.data.reason,
+              model: event.data.model,
               summary: event.data.text,
               recent: event.data.recent,
               time: { created: event.created },
diff --git a/packages/core/src/session/runner/llm.ts b/packages/core/src/session/runner/llm.ts
index 6a15137c07..56ed0e2f47 100644
--- a/packages/core/src/session/runner/llm.ts
+++ b/packages/core/src/session/runner/llm.ts
@@ -187,7 +187,7 @@ const layer = Layer.effect(
       const providerMetadataKey = model.route.providerMetadataKey ?? model.provider
       const history = yield* SessionHistory.entriesForRunner(db, session.id, instructions)
       const context = history.entries.map((entry) => entry.message)
-      const compactionInput = { sessionID: session.id, messages: context, model }
+      const compactionInput = { sessionID: session.id, messages: context, model, ref: resolved.ref }
       if (compaction.required(compactionInput) && !(yield* SessionPending.compaction(db, session.id))) {
         const compacted = yield* compaction.compact(compactionInput)
         if (compacted.status === "completed") return { _tag: "RestartAfterCompaction", step: currentStep } as const
@@ -331,8 +331,8 @@ const layer = Layer.effect(
             recoverOverflow &&
             !publisher.hasRetryEvidence() &&
             isContextOverflowFailure(overflowFailure ?? streamFailure) &&
-            (yield* restore(recoverOverflow({ sessionID: session.id, messages: context, model }))).status ===
-              "completed"
+            (yield* restore(recoverOverflow({ sessionID: session.id, messages: context, model, ref: resolved.ref })))
+              .status === "completed"
           )
             return { _tag: "RestartAfterOverflowCompaction", step: currentStep } as const
 
diff --git a/packages/core/test/session-compaction.test.ts b/packages/core/test/session-compaction.test.ts
index dc57b46f44..e3dc0770a1 100644
--- a/packages/core/test/session-compaction.test.ts
+++ b/packages/core/test/session-compaction.test.ts
@@ -154,7 +154,13 @@ it.effect("manual compaction summarizes short context instead of no-op", () =>
     expect(requests[0]?.generation).toBeUndefined()
     expect(JSON.stringify(requests[0]?.messages)).toContain("Manual compaction should include this short conversation.")
     expect(yield* store.context(sessionID)).toMatchObject([
-      { type: "compaction", reason: "manual", summary: "manual summary", recent: "" },
+      {
+        type: "compaction",
+        reason: "manual",
+        model: { id: "summary-model", providerID: "test" },
+        summary: "manual summary",
+        recent: "",
+      },
     ])
     expect(
       yield* db
diff --git a/packages/schema/src/session-event.ts b/packages/schema/src/session-event.ts
index 61341168ce..83caa2d7f7 100644
--- a/packages/schema/src/session-event.ts
+++ b/packages/schema/src/session-event.ts
@@ -488,6 +488,7 @@ export namespace Compaction {
     schema: {
       ...Base,
       reason: Started.data.fields.reason,
+      model: Model.Ref.pipe(optional),
       text: Schema.String,
       recent: Schema.String,
     },
diff --git a/packages/schema/src/session-message.ts b/packages/schema/src/session-message.ts
index 3d45e283e6..fe394f7a70 100644
--- a/packages/schema/src/session-message.ts
+++ b/packages/schema/src/session-message.ts
@@ -222,6 +222,7 @@ export const CompactionCompleted = Schema.Struct({
   ...CompactionBase,
   status: Schema.tag("completed"),
   reason: Schema.Literals(["auto", "manual"]),
+  model: Model.Ref.pipe(optional),
   summary: Schema.String,
   recent: Schema.String,
 }).annotate({ identifier: "Session.Message.Compaction.Completed" })
diff --git a/packages/schema/test/session-message.test.ts b/packages/schema/test/session-message.test.ts
new file mode 100644
index 0000000000..fb460a8e1c
--- /dev/null
+++ b/packages/schema/test/session-message.test.ts
@@ -0,0 +1,21 @@
+import { describe, expect, test } from "bun:test"
+import { Schema } from "effect"
+import { SessionMessage } from "../src/session-message.js"
+
+describe("session message", () => {
+  test("decodes completed compactions recorded before model attribution", () => {
+    const encoded = {
+      type: "compaction" as const,
+      id: "msg_compaction",
+      time: { created: 0 },
+      status: "completed" as const,
+      reason: "manual" as const,
+      summary: "summary",
+      recent: "",
+    }
+    const message = Schema.decodeUnknownSync(SessionMessage.CompactionCompleted)(encoded)
+
+    expect(message.model).toBeUndefined()
+    expect(Schema.encodeSync(SessionMessage.CompactionCompleted)(message)).toEqual(encoded)
+  })
+})
diff --git a/packages/tui/src/context/data.tsx b/packages/tui/src/context/data.tsx
index 114da13a1f..0e4c50b70a 100644
--- a/packages/tui/src/context/data.tsx
+++ b/packages/tui/src/context/data.tsx
@@ -732,6 +732,7 @@ export const { use: useData, provider: DataProvider } = createSimpleContext({
               Object.assign(current, {
                 status: "completed",
                 reason: event.data.reason,
+                model: event.data.model,
                 summary: event.data.text,
                 recent: event.data.recent,
               })
@@ -742,6 +743,7 @@ export const { use: useData, provider: DataProvider } = createSimpleContext({
               type: "compaction",
               status: "completed",
               reason: event.data.reason,
+              model: event.data.model,
               summary: event.data.text,
               recent: event.data.recent,
               time: { created: event.created },
diff --git a/packages/tui/src/routes/session/index.tsx b/packages/tui/src/routes/session/index.tsx
index f5dbb56408..3173d4f545 100644
--- a/packages/tui/src/routes/session/index.tsx
+++ b/packages/tui/src/routes/session/index.tsx
@@ -73,7 +73,7 @@ import { OPENCODE_BASE_MODE, useBindings, useCommandShortcut } from "../../keyma
 import { usePathFormatter } from "../../context/path-format"
 import { LocationProvider } from "../../context/location"
 import { createSessionRows, resolvePart, type PartRef, type SessionRow } from "./rows"
-import { switchLabel } from "../../util/model"
+import { compactionMarker, switchLabel } from "../../util/model"
 
 addDefaultParsers(parsers.parsers)
 
@@ -1306,10 +1306,14 @@ function SessionSkillMessage(props: { message: Extract<SessionMessageInfo, { typ
 
 function CompactionMessage(props: { message: Extract<SessionMessageInfo, { type: "compaction" }> }) {
   const ctx = use()
+  const local = useLocal()
   const { theme, syntax } = useTheme()
   const status = () => props.message.status
   const text = () => (props.message.status === "failed" ? props.message.error.message : props.message.summary)
   const content = createMemo(() => text().trim())
+  const marker = createMemo(() =>
+    compactionMarker(props.message.status === "completed" ? props.message.model : undefined, ctx.models()),
+  )
   const color = () => (status() === "failed" ? theme.error : theme.textMuted)
   return (
     <box>
@@ -1344,6 +1348,16 @@ function CompactionMessage(props: { message: Extract<SessionMessageInfo, { type:
           />
         </box>
       </Show>
+      <Show when={marker()}>
+        {(value) => (
+          <box paddingLeft={3} marginTop={1}>
+            <text>
+              <span style={{ fg: local.agent.color(value().agent) }}>{Locale.titlecase(value().agent)}</span>
+              <span style={{ fg: theme.textMuted }}> · {value().model}</span>
+            </text>
+          </box>
+        )}
+      </Show>
     </box>
   )
 }
diff --git a/packages/tui/src/util/model.ts b/packages/tui/src/util/model.ts
index 215602845f..6093cfccd6 100644
--- a/packages/tui/src/util/model.ts
+++ b/packages/tui/src/util/model.ts
@@ -7,6 +7,18 @@ export function formatRef(model: { providerID: string; id: string; variant?: str
   return [model.providerID, model.id, model.variant].filter((value) => value !== undefined).join("/")
 }
 
+export function compactionMarker(
+  model: { providerID: string; id: string; variant?: string } | undefined,
+  models?: readonly { providerID: string; id: string; name: string }[],
+) {
+  if (!model) return
+  return {
+    agent: "compaction",
+    model:
+      models?.find((item) => item.providerID === model.providerID && item.id === model.id)?.name ?? formatRef(model),
+  }
+}
+
 export function switchLabel(
   model: { providerID: string; id: string; variant?: string },
   models?: readonly { providerID: string; id: string; name: string }[],
diff --git a/packages/tui/test/cli/tui/data.test.tsx b/packages/tui/test/cli/tui/data.test.tsx
index 2671ba1e22..21317a0559 100644
--- a/packages/tui/test/cli/tui/data.test.tsx
+++ b/packages/tui/test/cli/tui/data.test.tsx
@@ -1126,7 +1126,13 @@ test("tracks session status from active sessions and execution events", async ()
       created: 0,
       type: "session.compaction.ended",
       durable: durable("session-live", 5),
-      data: { sessionID: "session-live", reason: "auto", text: "Live summary", recent: "recent" },
+      data: {
+        sessionID: "session-live",
+        reason: "auto",
+        model: { providerID: "anthropic", id: "claude-sonnet" },
+        text: "Live summary",
+        recent: "recent",
+      },
     })
     await wait(() => {
       const message = data.session.message.get("session-live", "msg_compaction_started")
@@ -1135,6 +1141,7 @@ test("tracks session status from active sessions and execution events", async ()
     expect(data.session.message.get("session-live", "msg_compaction_started")).toMatchObject({
       type: "compaction",
       status: "completed",
+      model: { providerID: "anthropic", id: "claude-sonnet" },
       summary: "Live summary",
     })
     expect(rows.find((row) => row.type === "message" && row.messageID === "msg_compaction_started")).toBe(
diff --git a/packages/tui/test/util/model.test.ts b/packages/tui/test/util/model.test.ts
index 888b102013..9e54d757ed 100644
--- a/packages/tui/test/util/model.test.ts
+++ b/packages/tui/test/util/model.test.ts
@@ -1,5 +1,5 @@
 import { describe, expect, test } from "bun:test"
-import { formatRef, parse, switchLabel } from "../../src/util/model"
+import { compactionMarker, formatRef, parse, switchLabel } from "../../src/util/model"
 
 describe("util.model", () => {
   test("splits provider from a nested model identifier", () => {
@@ -12,6 +12,20 @@ describe("util.model", () => {
     expect(formatRef({ providerID: "anthropic", id: "sonnet" })).toBe("anthropic/sonnet")
   })
 
+  test("labels completed compactions with their actual model", () => {
+    const models = [{ providerID: "anthropic", id: "sonnet", name: "Claude Sonnet" }]
+
+    expect(compactionMarker({ providerID: "anthropic", id: "sonnet" }, models)).toEqual({
+      agent: "compaction",
+      model: "Claude Sonnet",
+    })
+    expect(compactionMarker({ providerID: "removed", id: "gone", variant: "high" }, models)).toEqual({
+      agent: "compaction",
+      model: "removed/gone/high",
+    })
+    expect(compactionMarker(undefined, models)).toBeUndefined()
+  })
+
   test("includes the selected variant in model switch notices", () => {
     expect(switchLabel({ providerID: "anthropic", id: "sonnet", variant: "thinking" })).toBe(
       "Switched model to anthropic/sonnet/thinking",