fix(desktop): show merge results as automatic notices

apps/desktop/src/state/host.test.ts

@@ -1,5 +1,23 @@
 import { expect, test } from "bun:test";
-import { noProviderPullList } from "./host";
+import { type JsonObject, obj, str } from "../acp/jsonrpc";
+import { mergeResultNotice, noProviderPullList } from "./host";
+import { isContinueMessage, noticeLine } from "./thread";
+
+test("background merge results are durable notices with the complete outcome for the agent", () => {
+  const results: JsonObject[] = [
+    { state: "merged", merged: true, detail: "Squash-merged and the remote branch was deleted" },
+    { state: "failing", merged: false, failing: ["Desktop"], detail: "Checks failed" },
+    { error: { code: "failed", message: "The engine did not answer" } },
+  ];
+  for (const result of results) {
+    const text = mergeResultNotice(3792, result);
+    expect(isContinueMessage(text)).toBe(true);
+    expect(noticeLine(text)).toBe(
+      `Pull request #3792: ${str(result.detail) || str(obj(result.error)?.message)}`,
+    );
+    expect(text).toContain(JSON.stringify(result));
+  }
+});
 
 test("unsupported remote returns an empty pull request list with a note", () => {
   expect(noProviderPullList({ code: "no_provider" }, {})).toEqual({

apps/desktop/src/state/host.ts

@@ -258,6 +258,7 @@ import {
   type QueuedPrompt,
   type TranscriptItem,
   turnCompletion,
+  withPullMark,
 } from "./thread";
 import { isRemoteThread, LOCAL_HOST, splitThreadKey, threadKey } from "./threadKeys";
 import { orchestrationTool } from "./toolNames";
@@ -3221,9 +3222,7 @@ async function mergeTracked(
     };
   };
   if (call.number) {
-    void finishMerge().then((result) =>
-      deliver(caller.id, `Pull request #${pull.number}: ${JSON.stringify(result)}`, "", ""),
-    );
+    void finishMerge().then((result) => deliver(caller.id, mergeResultNotice(pull.number, result), "", ""));
     return {
       number: pull.number,
       state: "watching",
@@ -3233,6 +3232,13 @@ async function mergeTracked(
   return finishMerge();
 }
 
+/** Keep the full result for the agent beneath the persistent, human-readable notice line. */
+export function mergeResultNotice(number: number, result: JsonObject): string {
+  const summary =
+    str(result.detail) || str(obj(result.error)?.message) || str(result.state) || "Merge failed";
+  return withPullMark(`Pull request #${number}: ${summary}\n\n${JSON.stringify(result)}`);
+}
+
 /**
  * `cleanup_worktree`: removes a merged delegate's worktree and branch, then
  * settles it, after the engine confirms nothing unique is lost (git cherry,