diff --git a/packages/tui/test/message-trailer.view.test.tsx b/packages/tui/test/message-trailer.view.test.tsx
new file mode 100644
index 0000000000..48e720d17d
--- /dev/null
+++ b/packages/tui/test/message-trailer.view.test.tsx
@@ -0,0 +1,154 @@
+import { expect, mock, test } from "bun:test"
+import type { TuiPluginApi } from "@opencode-ai/plugin/tui"
+import { createTestRenderer } from "@opentui/core/testing"
+import { Effect } from "effect"
+import { AppNodeBuilder } from "@opencode-ai/core/effect/app-node-builder"
+import { Global } from "@opencode-ai/core/global"
+import { createTuiResolvedConfig } from "./fixture/tui-runtime"
+import { createEventSource, createFetch, directory, json } from "./fixture/tui-sdk"
+
+async function waitForFrame(setup: Awaited<ReturnType<typeof createTestRenderer>>, fn: (frame: string) => boolean) {
+  const start = Date.now()
+  while (true) {
+    await setup.renderOnce()
+    const frame = setup.captureCharFrame()
+    if (fn(frame)) return frame
+    if (Date.now() - start > 15_000) throw new Error("timed out waiting for frame:\n" + frame)
+    await Bun.sleep(25)
+  }
+}
+
+// The last assistant message's trailer normally repeats the agent and model the
+// prompt footer already shows; when they match the current selection the fork
+// collapses it to "Baked for <duration>", and cycling to another agent brings
+// the full trailer back (see DIVERGENCES.md).
+test("last-message trailer collapses to Baked for and reappears on agent switch", async () => {
+  // Wide enough that the footer keeps agent · model on one line.
+  const setup = await createTestRenderer({ width: 120, height: 30, useThread: false })
+  const core = await import("@opentui/core")
+  mock.module("@opentui/core", () => ({ ...core, createCliRenderer: async () => setup.renderer }))
+  const events = createEventSource()
+  const session = {
+    id: "ses_test",
+    title: "Demo session",
+    slug: "test",
+    projectID: "proj_test",
+    directory,
+    version: "0.0.0-test",
+    time: { created: 1, updated: 1 },
+  }
+  const calls = createFetch((url) => {
+    if (url.pathname === "/session") return json([session])
+    if (url.pathname === "/session/ses_test") return json(session)
+    // Two primary agents so agent.cycle has somewhere to go.
+    if (url.pathname === "/agent")
+      return json([
+        { name: "build", mode: "primary" },
+        { name: "plan", mode: "primary" },
+      ])
+    if (url.pathname === "/session/ses_test/message")
+      return json([
+        {
+          info: {
+            id: "msg_1",
+            sessionID: "ses_test",
+            role: "user",
+            agent: "build",
+            model: { providerID: "test", modelID: "m1" },
+            time: { created: 1000 },
+          },
+          parts: [{ id: "prt_1", sessionID: "ses_test", messageID: "msg_1", type: "text", text: "hello there" }],
+        },
+        {
+          // Completed turn by the currently selected agent and model, so the
+          // trailer's agent · model would duplicate the footer.
+          info: {
+            id: "msg_2",
+            sessionID: "ses_test",
+            role: "assistant",
+            agent: "build",
+            mode: "build",
+            parentID: "msg_1",
+            modelID: "m1",
+            providerID: "test",
+            finish: "stop",
+            path: { cwd: directory, root: directory },
+            cost: 0,
+            tokens: { input: 1, output: 1, reasoning: 0, cache: { read: 0, write: 0 } },
+            time: { created: 2000, completed: 2600 },
+          },
+          parts: [{ id: "prt_2", sessionID: "ses_test", messageID: "msg_2", type: "text", text: "All good." }],
+        },
+      ])
+    if (url.pathname === "/session/ses_test/todo") return json([])
+    if (url.pathname === "/session/ses_test/diff") return json([])
+    if (url.pathname === "/project/proj_test/directories") return json([])
+    // A paid model keeps the fork's first-run configure dialog closed; it is
+    // also the fallback selection every agent resolves to.
+    if (url.pathname === "/config/providers")
+      return json({
+        providers: [
+          {
+            id: "test",
+            name: "Test",
+            models: { m1: { name: "M1", cost: { input: 1 }, limit: { context: 200_000, output: 8_192 } } },
+          },
+        ],
+        default: { test: "m1" },
+      })
+    return undefined
+  })
+  let api: TuiPluginApi | undefined
+  let started!: () => void
+  const ready = new Promise<void>((resolve) => {
+    started = resolve
+  })
+
+  try {
+    const { run } = await import("../src/app")
+    const task = Effect.runPromise(
+      run({
+        url: "http://test",
+        directory,
+        config: createTuiResolvedConfig({ plugin_enabled: {} }),
+        fetch: calls.fetch,
+        events: events.source,
+        args: { continue: true },
+        pluginHost: {
+          // The session prompt is a slot default; the slot view renders
+          // nothing until the slot registry is set up.
+          async start(input) {
+            input.runtime.setupSlots(input.api)
+            api = input.api
+            started()
+          },
+          async dispose() {},
+        },
+      }).pipe(Effect.provide(AppNodeBuilder.build(Global.node))),
+    )
+    await ready
+
+    // Suppressed: duration only, no marker, no agent · model copy.
+    const suppressed = await waitForFrame(setup, (frame) => frame.includes("Baked for 1.6s"))
+    expect(suppressed).not.toContain("▣")
+    expect(suppressed).not.toContain("Build · M1")
+
+    // Switching agents breaks the match, so the full trailer comes back.
+    api?.keymap.dispatchCommand("agent.cycle")
+    const full = await waitForFrame(setup, (frame) => frame.includes("Build · M1"))
+    expect(full).toContain("▣")
+    expect(full).toContain("Build · M1 · 1.6s")
+    expect(full).not.toContain("Baked for")
+
+    // And cycling back restores the suppression.
+    api?.keymap.dispatchCommand("agent.cycle")
+    const again = await waitForFrame(setup, (frame) => frame.includes("Baked for 1.6s"))
+    expect(again).not.toContain("▣")
+
+    process.emit("SIGHUP")
+    await task
+  } finally {
+    if (!setup.renderer.isDestroyed) setup.renderer.destroy()
+    mock.restore()
+  }
+}, 30_000)