feat(FN-5047): emit task:merged across merge finalize paths

Fusion-Task-Id: FN-5047
Fusion-Task-Lineage: 9b03f2de-1b4a-45ad-b1ce-0a6217d6da77

packages/cli/src/commands/__tests__/task-lifecycle.test.ts

@@ -52,7 +52,7 @@ function makeStore(task: MockTask, settings: Record<string, unknown> = {}) {
       updates.push({ id, patch });
     }),
     updatePrInfo: vi.fn().mockResolvedValue(undefined),
-    moveTask: vi.fn().mockResolvedValue(undefined),
+    moveTask: vi.fn(async (_id: string, column: string) => ({ ...task, column })),
     logEntry: vi.fn().mockResolvedValue(undefined),
     getActiveMergingTask: vi.fn().mockReturnValue(null),
     _updates: updates,
@@ -74,6 +74,7 @@ function makeStatefulStore(task: MockTask, settings: Record<string, unknown> = {
     }),
     moveTask: vi.fn(async (_id: string, column: string) => {
       state = { ...state, column };
+      return structuredClone(state);
     }),
     logEntry: vi.fn().mockResolvedValue(undefined),
     getActiveMergingTask: vi.fn().mockReturnValue(null),
@@ -732,6 +733,11 @@ describe("processPullRequestMergeTask", () => {
       mergePr: vi.fn(async () => mergedPr),
     };
 
+    const mergedEvents: unknown[] = [];
+    store.on("task:merged", (result) => {
+      mergedEvents.push(result);
+    });
+
     const result = await processPullRequestMergeTask(
       store as never,
       "/repo",
@@ -746,6 +752,13 @@ describe("processPullRequestMergeTask", () => {
     expect(persisted.prInfo?.number).toBe(123);
     expect(persisted.prInfo?.url).toBe("https://github.com/x/y/pull/123");
     expect(store.updatePrInfo).toHaveBeenCalledTimes(3);
+    expect(mergedEvents).toHaveLength(1);
+    expect(mergedEvents[0]).toEqual(
+      expect.objectContaining({
+        merged: true,
+        task: expect.objectContaining({ id: task.id, column: "done" }),
+      }),
+    );
   });
 
   describe("requirePrApproval", () => {

packages/cli/src/commands/task-lifecycle.ts

@@ -18,7 +18,7 @@ import { promisify } from "node:util";
 const execAsync = promisify(exec);
 import type { TaskStore } from "@fusion/core";
 import { resolveTaskMergeTarget } from "@fusion/core";
-import type { Settings, TaskDetail, PrInfo } from "@fusion/core";
+import type { Settings, TaskDetail, PrInfo, MergeResult } from "@fusion/core";
 
 /**
  * Minimal interface for GitHub operations needed by the PR merge workflow.
@@ -179,8 +179,23 @@ async function finalizePullRequestMerge(
 ): Promise<void> {
   await cleanupMergedTaskArtifacts(cwd, task);
   await store.updateTask(task.id, { status: null, mergeRetries: 0 });
-  await store.moveTask(task.id, "done");
+  const movedTask = await store.moveTask(task.id, "done");
+  const mergedTask = movedTask ?? (await store.getTask(task.id));
   await store.logEntry(task.id, message, `PR #${prInfo.number}: ${prInfo.url}`);
+  const settings = await store.getSettings();
+  const mergeTargetBranch = resolveTaskMergeTarget(mergedTask, {
+    projectDefaultBranch: typeof settings.baseBranch === "string" ? settings.baseBranch : undefined,
+  });
+  store.emit("task:merged", {
+    task: mergedTask,
+    branch: mergedTask.branch ?? getTaskBranchName(task.id),
+    merged: true,
+    worktreeRemoved: false,
+    branchDeleted: false,
+    mergeConfirmed: mergedTask.mergeDetails?.mergeConfirmed ?? true,
+    mergedAt: mergedTask.mergeDetails?.mergedAt,
+    mergeTargetBranch,
+  } as MergeResult);
 }
 
 /**