feat(KB-093): add PR-first merge mode with configurable merge strategies

- Add mergeStrategy setting (fast-forward, squash, merge-commit) to config
- Implement PR-first auto-completion flow that monitors PR merge status
- Wire PR monitoring service to detect merge completion and trigger auto-close
- Add PR status UI to dashboard with merge progress indicator
- Update settings modal with merge strategy selector
- Add changeset for PR-first merge mode feature

packages/core/src/store.test.ts

@@ -384,6 +384,19 @@ describe("TaskStore", () => {
     });
   });
 
+  describe("mergeStrategy setting", () => {
+    it("defaults mergeStrategy to direct for backward compatibility", async () => {
+      const settings = await store.getSettings();
+      expect(settings.mergeStrategy).toBe("direct");
+    });
+
+    it("persists mergeStrategy and returns it via getSettings", async () => {
+      await store.updateSettings({ mergeStrategy: "pull-request" });
+      const settings = await store.getSettings();
+      expect(settings.mergeStrategy).toBe("pull-request");
+    });
+  });
+
   // ── Concurrent stress test ───────────────────────────────────────
 
   describe("concurrent stress", () => {

packages/core/src/types.ts

@@ -23,6 +23,7 @@ export const COLOR_THEMES = [
 export type ColorTheme = (typeof COLOR_THEMES)[number];
 
 export type PrStatus = "open" | "closed" | "merged";
+export type MergeStrategy = "direct" | "pull-request";
 
 export interface PrInfo {
   url: string;
@@ -195,6 +196,12 @@ export interface Settings {
   pollIntervalMs: number;
   groupOverlappingFiles: boolean;
   autoMerge: boolean;
+  /** How completed in-review tasks should be finalized when autoMerge is enabled.
+   *  - "direct": preserve the existing local squash-merge flow into the current branch
+   *  - "pull-request": create or reuse a GitHub PR and wait for GitHub-side checks/reviews
+   *    before merging through GitHub
+   *  Default: "direct" for backward compatibility. */
+  mergeStrategy?: MergeStrategy;
   /** Shell command to run inside each new worktree immediately after creation.
    *  Useful for project-specific setup (e.g. `pnpm install`, `cp .env.local .env`). */
   worktreeInitCommand?: string;
@@ -271,6 +278,7 @@ export const DEFAULT_SETTINGS: Settings = {
   pollIntervalMs: 15000,
   groupOverlappingFiles: false,
   autoMerge: true,
+  mergeStrategy: "direct",
   worktreeInitCommand: undefined,
   recycleWorktrees: false,
   worktreeNaming: "random",