fix(tui): restore compaction model marker

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(

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",