diff --git a/packages/engine/src/__tests__/group-merge-coordinator.test.ts b/packages/engine/src/__tests__/group-merge-coordinator.test.ts
index 8889e630db..35bd67d7d2 100644
--- a/packages/engine/src/__tests__/group-merge-coordinator.test.ts
+++ b/packages/engine/src/__tests__/group-merge-coordinator.test.ts
@@ -9,6 +9,7 @@ import {
   evaluateBranchGroupCompletion,
   evaluateBranchGroupPromotion,
   promoteBranchGroup,
+  reconcileBranchGroupPr,
   resolveBranchGroupMergeRouting,
 } from "../group-merge-coordinator.js";
 import { ProjectEngine } from "../project-engine.js";
@@ -639,6 +640,310 @@ describe("ProjectEngine.promoteBranchGroup (U4 bridge method)", () => {
   });
 });
 
+describe("promoteBranchGroup concurrency lock (Fix #10)", () => {
+  function makeGroup(overrides?: Partial<any>): any {
+    return {
+      id: "BG-LOCK-1",
+      sourceType: "planning",
+      sourceId: "planning:x",
+      branchName: "fusion/groups/planning-x",
+      autoMerge: true,
+      prState: "none",
+      status: "open",
+      createdAt: Date.now(),
+      updatedAt: Date.now(),
+      ...overrides,
+    };
+  }
+
+  const landedMember = (id: string, branchName: string) => ({
+    id,
+    title: `${id} title`,
+    column: "done" as const,
+    mergeDetails: {
+      mergeConfirmed: true,
+      mergeTargetSource: "branch-group-integration",
+      mergeTargetBranch: branchName,
+    },
+  });
+
+  function makePrRepo(): string {
+    const rootDir = makeRepo();
+    execSync("git checkout -b fusion/groups/planning-x", { cwd: rootDir });
+    execSync("echo promoted > group.txt", { cwd: rootDir, shell: "/bin/bash" });
+    execSync("git add group.txt && git commit -m group", { cwd: rootDir, shell: "/bin/bash" });
+    execSync("git checkout main", { cwd: rootDir });
+    return rootDir;
+  }
+
+  const prSettings = {
+    autoMerge: true,
+    globalPause: false,
+    enginePaused: false,
+    mergeStrategy: "pull-request" as const,
+    baseBranch: "main",
+  };
+
+  it("serializes two concurrent promotions: createGroupPr runs exactly once, one PR persisted", async () => {
+    const rootDir = makePrRepo();
+    let group = makeGroup();
+    let createCalls = 0;
+    const store = {
+      getBranchGroup: () => group,
+      getBranchGroupByBranchName: () => null,
+      listTasksByBranchGroup: async () => [landedMember("FN-A", group.branchName)],
+      updateBranchGroup: (_id: string, patch: Record<string, unknown>) => {
+        group = { ...group, ...patch };
+        return group;
+      },
+    } as any;
+
+    // The injected creator yields (await a macrotask) so that, WITHOUT the lock,
+    // a second concurrent call would slip past the prState/status gate (which is
+    // read at the top, before the first call has persisted "open") and create a
+    // second PR. With the per-group lock the second call only begins after the
+    // first persisted its result and short-circuits as already-finalized.
+    const createGroupPr = async () => {
+      createCalls += 1;
+      const n = createCalls;
+      await new Promise((resolve) => setTimeout(resolve, 25));
+      return { prNumber: 40 + n, prUrl: `https://github.com/x/y/pull/${40 + n}`, prState: "open" as const };
+    };
+
+    const [a, b] = await Promise.all([
+      promoteBranchGroup({ rootDir, groupId: group.id, settings: prSettings, store, createGroupPr }),
+      promoteBranchGroup({ rootDir, groupId: group.id, settings: prSettings, store, createGroupPr }),
+    ]);
+
+    expect(createCalls).toBe(1);
+    expect(group.prNumber).toBe(41);
+    expect(group.prState).toBe("open");
+    expect(group.status).toBe("finalized");
+
+    // Exactly one call reports a fresh promotion; the other sees already-finalized.
+    const reasons = [a.reason, b.reason].sort();
+    expect(reasons).toEqual(["already-finalized", "promoted"]);
+    const promoted = [a, b].filter((r) => r.reason === "promoted");
+    expect(promoted).toHaveLength(1);
+    expect(promoted[0].prNumber).toBe(41);
+  });
+});
+
+describe("promoteBranchGroup finalized-but-PR-less repair (Fix #4 part 2)", () => {
+  function makeGroup(overrides?: Partial<any>): any {
+    return {
+      id: "BG-REPAIR-1",
+      sourceType: "planning",
+      sourceId: "planning:x",
+      branchName: "fusion/groups/planning-x",
+      autoMerge: true,
+      prState: "none",
+      status: "open",
+      createdAt: Date.now(),
+      updatedAt: Date.now(),
+      ...overrides,
+    };
+  }
+
+  const landedMember = (id: string, branchName: string) => ({
+    id,
+    title: `${id} title`,
+    column: "done" as const,
+    mergeDetails: {
+      mergeConfirmed: true,
+      mergeTargetSource: "branch-group-integration",
+      mergeTargetBranch: branchName,
+    },
+  });
+
+  function makePrRepo(): string {
+    const rootDir = makeRepo();
+    execSync("git checkout -b fusion/groups/planning-x", { cwd: rootDir });
+    execSync("echo promoted > group.txt", { cwd: rootDir, shell: "/bin/bash" });
+    execSync("git add group.txt && git commit -m group", { cwd: rootDir, shell: "/bin/bash" });
+    execSync("git checkout main", { cwd: rootDir });
+    return rootDir;
+  }
+
+  const prSettings = {
+    autoMerge: true,
+    globalPause: false,
+    enginePaused: false,
+    mergeStrategy: "pull-request" as const,
+    baseBranch: "main",
+  };
+
+  it("re-promotion creates the PR for a finalized PR-less group WITHOUT re-running the integration merge", async () => {
+    const rootDir = makePrRepo();
+    // Simulate a crash AFTER the integration merge + finalize but BEFORE the PR
+    // was created: group is finalized, prState none, prNumber null.
+    let group = makeGroup({ status: "finalized", prState: "none", prNumber: null, prUrl: null });
+    let createCalls = 0;
+    let mergeCalls = 0;
+    const store = {
+      getBranchGroup: () => group,
+      getBranchGroupByBranchName: () => null,
+      listTasksByBranchGroup: async () => [landedMember("FN-A", group.branchName)],
+      updateBranchGroup: (_id: string, patch: Record<string, unknown>) => {
+        group = { ...group, ...patch };
+        return group;
+      },
+    } as any;
+
+    // Detect whether the integration merge ran by recording the merge commit on
+    // main before re-promotion. The repair path must NOT advance main again.
+    const mainBefore = execSync("git rev-parse main", { cwd: rootDir, encoding: "utf8" }).trim();
+    void mergeCalls;
+
+    const result = await promoteBranchGroup({
+      rootDir,
+      groupId: group.id,
+      settings: prSettings,
+      store,
+      createGroupPr: async ({ members }) => {
+        createCalls += 1;
+        expect(members.map((m: any) => m.id)).toEqual(["FN-A"]);
+        return { prNumber: 77, prUrl: "https://github.com/x/y/pull/77", prState: "open" as const };
+      },
+    });
+
+    expect(result.reason).toBe("promoted");
+    expect(createCalls).toBe(1);
+    expect(group.prNumber).toBe(77);
+    expect(group.prState).toBe("open");
+    expect(group.status).toBe("finalized");
+
+    // The merge step was skipped: main is unchanged from before the repair.
+    const mainAfter = execSync("git rev-parse main", { cwd: rootDir, encoding: "utf8" }).trim();
+    expect(mainAfter).toBe(mainBefore);
+  });
+
+  it("a finalized group that already has a prNumber is still short-circuited (no repair, no PR re-create)", async () => {
+    const rootDir = makePrRepo();
+    let group = makeGroup({ status: "finalized", prState: "open", prNumber: 5, prUrl: "https://github.com/x/y/pull/5" });
+    let createCalls = 0;
+    const store = {
+      getBranchGroup: () => group,
+      getBranchGroupByBranchName: () => null,
+      listTasksByBranchGroup: async () => [landedMember("FN-A", group.branchName)],
+      updateBranchGroup: () => {
+        throw new Error("should not update an already-PR'd finalized group");
+      },
+    } as any;
+
+    const result = await promoteBranchGroup({
+      rootDir,
+      groupId: group.id,
+      settings: prSettings,
+      store,
+      createGroupPr: async () => {
+        createCalls += 1;
+        return { prNumber: 1, prUrl: "x", prState: "open" as const };
+      },
+    });
+
+    expect(result.reason).toBe("already-finalized");
+    expect(createCalls).toBe(0);
+  });
+});
+
+describe("reconcileBranchGroupPr (Fix #3 engine primitive)", () => {
+  function makeGroup(overrides?: Partial<any>): any {
+    return {
+      id: "BG-RECON-1",
+      sourceType: "planning",
+      sourceId: "planning:x",
+      branchName: "fusion/groups/planning-x",
+      autoMerge: true,
+      prState: "open",
+      prNumber: 12,
+      prUrl: "https://github.com/x/y/pull/12",
+      status: "finalized",
+      createdAt: Date.now(),
+      updatedAt: Date.now(),
+      ...overrides,
+    };
+  }
+
+  it("persists merged state when syncGroupPr reports the PR merged", async () => {
+    let group = makeGroup();
+    const updates: Array<Record<string, unknown>> = [];
+    const store = {
+      listTasksByBranchGroup: async () => [{ id: "FN-A" }],
+      updateBranchGroup: (_id: string, patch: Record<string, unknown>) => {
+        updates.push(patch);
+        group = { ...group, ...patch };
+        return group;
+      },
+    } as any;
+
+    const result = await reconcileBranchGroupPr({
+      store,
+      group,
+      syncGroupPr: async () => ({
+        prNumber: 12,
+        prUrl: "https://github.com/x/y/pull/12",
+        prState: "merged",
+      }),
+    });
+
+    expect(result.reconciled).toBe(true);
+    expect(result.prState).toBe("merged");
+    expect(group.prState).toBe("merged");
+    expect(updates).toHaveLength(1);
+    expect(updates[0]).toMatchObject({ prState: "merged", prNumber: 12 });
+  });
+
+  it("is a no-op (no persist) when the PR is still open", async () => {
+    const group = makeGroup();
+    let updateCalls = 0;
+    const store = {
+      listTasksByBranchGroup: async () => [{ id: "FN-A" }],
+      updateBranchGroup: () => {
+        updateCalls += 1;
+        return group;
+      },
+    } as any;
+
+    const result = await reconcileBranchGroupPr({
+      store,
+      group,
+      syncGroupPr: async () => ({
+        prNumber: 12,
+        prUrl: "https://github.com/x/y/pull/12",
+        prState: "open",
+      }),
+    });
+
+    expect(result.reconciled).toBe(false);
+    expect(result.prState).toBe("open");
+    expect(updateCalls).toBe(0);
+  });
+
+  it("is a no-op when the group has no persisted prNumber", async () => {
+    const group = makeGroup({ prNumber: null, prState: "none" });
+    let syncCalls = 0;
+    const store = {
+      listTasksByBranchGroup: async () => [{ id: "FN-A" }],
+      updateBranchGroup: () => {
+        throw new Error("should not update");
+      },
+    } as any;
+
+    const result = await reconcileBranchGroupPr({
+      store,
+      group,
+      syncGroupPr: async () => {
+        syncCalls += 1;
+        return { prNumber: 0, prUrl: "", prState: "open" as const };
+      },
+    });
+
+    expect(result.reconciled).toBe(false);
+    expect(syncCalls).toBe(0);
+  });
+});
+
 describe("resolveBranchGroupMergeRouting", () => {
   it("returns null for non-shared tasks", async () => {
     const routing = await resolveBranchGroupMergeRouting({
diff --git a/packages/engine/src/__tests__/project-engine.test.ts b/packages/engine/src/__tests__/project-engine.test.ts
index 4d9774959a..e7b7a98de1 100644
--- a/packages/engine/src/__tests__/project-engine.test.ts
+++ b/packages/engine/src/__tests__/project-engine.test.ts
@@ -1782,6 +1782,73 @@ describe("ProjectEngine paused in-review auto-merge behavior", () => {
     await engine.stop();
   });
 
+  it("records an audit event (not silent) when auto-promotion of a branch-group member fails (Fix #4)", async () => {
+    const mockStore = createMockStore({ ...baseSettings, autoMerge: true });
+    // The dequeued + merged task is a shared branch-group member, so the engine
+    // attempts branch-group promotion after the PR merges.
+    const mergedMember = {
+      id: "FN-bgfail",
+      column: "done",
+      paused: false,
+      mergeRetries: 0,
+      status: null,
+      branch: "fusion/fn-bgfail",
+      branchContext: { groupId: "BG-FAIL-1", source: "planning", assignmentMode: "shared" },
+      mergeDetails: { mergeConfirmed: true, mergedAt: "2026-06-03T00:00:00.000Z", mergeTargetBranch: "fusion/groups/x" },
+    };
+    mockStore.store.getTask
+      .mockResolvedValueOnce({
+        id: "FN-bgfail",
+        column: "in-review",
+        paused: false,
+        mergeRetries: 0,
+        status: null,
+        branch: "fusion/fn-bgfail",
+        branchContext: { groupId: "BG-FAIL-1", source: "planning", assignmentMode: "shared" },
+      })
+      .mockResolvedValue(mergedMember);
+
+    const recordRunAuditEvent = vi.fn(async () => undefined);
+    // Drive promoteBranchGroup into throwing: getBranchGroup returns a complete-
+    // looking group, but listTasksByBranchGroup rejects, so promotion throws and
+    // the engine's catch must record the failure audit instead of swallowing it.
+    (mockStore.store as any).getBranchGroup = vi.fn(() => ({
+      id: "BG-FAIL-1",
+      sourceType: "planning",
+      sourceId: "planning:x",
+      branchName: "fusion/groups/x",
+      autoMerge: true,
+      prState: "none",
+      status: "open",
+      createdAt: Date.now(),
+      updatedAt: Date.now(),
+    }));
+    (mockStore.store as any).getBranchGroupByBranchName = vi.fn(() => null);
+    (mockStore.store as any).listTasksByBranchGroup = vi.fn(async () => {
+      throw new Error("boom: store unavailable");
+    });
+    (mockStore.store as any).updateBranchGroup = vi.fn();
+    (mockStore.store as any).recordRunAuditEvent = recordRunAuditEvent;
+    mocks.currentStore = mockStore.store;
+
+    const processPullRequestMerge = vi.fn(async () => "merged" as const);
+    const engine = createEngine({ processPullRequestMerge, getMergeStrategy: () => "pull-request" });
+    await engine.start();
+    engine.enqueueMerge("FN-bgfail");
+
+    await vi.waitFor(() => {
+      expect(recordRunAuditEvent).toHaveBeenCalledWith(
+        expect.objectContaining({
+          mutationType: "merge:branch-group-promotion-failed",
+          target: "BG-FAIL-1",
+          metadata: expect.objectContaining({ groupId: "BG-FAIL-1", taskId: "FN-bgfail" }),
+        }),
+      );
+    });
+
+    await engine.stop();
+  });
+
   it("logs and skips paused tasks dequeued for auto-merge", async () => {
     const mockStore = createMockStore({ ...baseSettings, autoMerge: true });
     mockStore.store.getTask.mockResolvedValueOnce({
diff --git a/packages/engine/src/group-merge-coordinator.ts b/packages/engine/src/group-merge-coordinator.ts
index f0a9452e85..a77adbda3d 100644
--- a/packages/engine/src/group-merge-coordinator.ts
+++ b/packages/engine/src/group-merge-coordinator.ts
@@ -173,11 +173,30 @@ async function ensureGroupBranchExists(rootDir: string, branchName: string, star
   }
 }
 
+/**
+ * Per-`groupId` in-process promotion lock (Fix #10). `promoteBranchGroup` can be
+ * invoked concurrently — e.g. the dashboard route bridge and the auto-promotion
+ * hook firing on the final member landing — and its body runs a long await chain
+ * (git checkout/merge on the shared working tree + PR creation) with no atomicity.
+ * Interleaving two runs can double-create the managed PR and corrupt HEAD.
+ *
+ * We serialize per group by chaining each call onto a promise stored in this map;
+ * each call only begins after the previous one for the same group settles, and it
+ * RE-READS the group state inside the lock (the inner function's first action is
+ * `store.getBranchGroup`), so a second waiter observes the first's persisted
+ * `prState`/`status` and short-circuits instead of re-doing the work.
+ *
+ * In-process only: a cross-node lease (FN-4820) is explicitly deferred.
+ */
+const promotionLocks = new Map<string, Promise<unknown>>();
+
 /**
  * The only entrypoint allowed to perform shared-branch-group → default-branch promotion.
  * Promotion is intentionally idempotent and must never run inline in aiMergeTask.
+ *
+ * Serialized per `groupId` via {@link promotionLocks}; see that comment for why.
  */
-export async function promoteBranchGroup(input: {
+export interface PromoteBranchGroupInput {
   store: Pick<TaskStore, "getBranchGroup" | "getBranchGroupByBranchName" | "listTasksByBranchGroup" | "updateBranchGroup">;
   rootDir: string;
   groupId: string;
@@ -194,7 +213,32 @@ export async function promoteBranchGroup(input: {
     target: string;
     metadata?: Record<string, unknown>;
   }) => Promise<void> | void;
-}): Promise<BranchGroupPromotionResult> {
+}
+
+export async function promoteBranchGroup(input: PromoteBranchGroupInput): Promise<BranchGroupPromotionResult> {
+  // Chain onto any in-flight promotion for this group so two concurrent callers
+  // (route bridge + auto-promotion on final landing) never run the merge/PR-create
+  // sequence at the same time. The continuation re-reads group state inside the
+  // lock, so the second caller observes the first's persisted result.
+  const prior = promotionLocks.get(input.groupId) ?? Promise.resolve();
+  const run = prior
+    .catch(() => {
+      // A failed prior promotion must not poison the chain; the next caller still
+      // gets a fresh, serialized attempt (re-merge is a no-op; PR-create idempotent).
+    })
+    .then(() => promoteBranchGroupInner(input));
+  promotionLocks.set(input.groupId, run);
+  try {
+    return await run;
+  } finally {
+    // Only clear if no newer call has chained on top of us.
+    if (promotionLocks.get(input.groupId) === run) {
+      promotionLocks.delete(input.groupId);
+    }
+  }
+}
+
+async function promoteBranchGroupInner(input: PromoteBranchGroupInput): Promise<BranchGroupPromotionResult> {
   const group = input.store.getBranchGroup(input.groupId);
   if (!group) {
     return {
@@ -207,7 +251,21 @@ export async function promoteBranchGroup(input: {
     };
   }
 
-  if (group.status === "finalized" || group.prState === "merged") {
+  const isPrMode = input.settings.mergeStrategy === "pull-request";
+
+  // Fix #4 (2): a group that finalized but never gained its PR — e.g. a crash
+  // between the local integration merge and a successful createGroupPr — would be
+  // permanently stranded by the already-finalized short-circuit below. When in PR
+  // mode and the finalized group has no persisted PR number, fall through to the
+  // PR-creation step ONLY (the integration merge already happened, so we skip it)
+  // so a re-promotion can repair it.
+  const needsPrRepair =
+    isPrMode &&
+    group.status === "finalized" &&
+    group.prState !== "merged" &&
+    (group.prNumber === null || group.prNumber === undefined);
+
+  if (!needsPrRepair && (group.status === "finalized" || group.prState === "merged")) {
     return {
       groupId: group.id,
       promoted: false,
@@ -234,58 +292,64 @@ export async function promoteBranchGroup(input: {
   }
 
   const members = await input.store.listTasksByBranchGroup(group.id);
-  const completion = evaluateBranchGroupCompletion({ members, group });
-  if (!completion.complete) {
-    return {
-      groupId: group.id,
-      promoted: false,
-      alreadyFinalized: false,
-      reason: "incomplete",
-      status: group.status,
-      prState: group.prState,
-      prNumber: group.prNumber,
-      prUrl: group.prUrl,
-    };
-  }
 
-  const eligibility = evaluateBranchGroupPromotion({ group, settings: input.settings });
-  if (!eligibility.eligible) {
-    await input.recordAudit?.({
-      domain: "git",
-      mutationType: "merge:branch-group-promotion-gated",
-      target: group.id,
-      metadata: {
+  // On the PR-repair path the group is already finalized — completion and
+  // eligibility were satisfied at finalization, and the integration merge already
+  // landed. Re-gating/re-merging would be wrong, so we skip straight to PR-create.
+  if (!needsPrRepair) {
+    const completion = evaluateBranchGroupCompletion({ members, group });
+    if (!completion.complete) {
+      return {
         groupId: group.id,
-        branchName: group.branchName,
-        groupAutoMerge: eligibility.groupAutoMerge,
-        effectiveEligible: false,
-        reason: eligibility.reason,
-      },
-    });
-    return {
-      groupId: group.id,
-      promoted: false,
-      alreadyFinalized: false,
-      reason: "gated",
-      status: group.status,
-      prState: group.prState,
-      prNumber: group.prNumber,
-      prUrl: group.prUrl,
-    };
+        promoted: false,
+        alreadyFinalized: false,
+        reason: "incomplete",
+        status: group.status,
+        prState: group.prState,
+        prNumber: group.prNumber,
+        prUrl: group.prUrl,
+      };
+    }
+
+    const eligibility = evaluateBranchGroupPromotion({ group, settings: input.settings });
+    if (!eligibility.eligible) {
+      await input.recordAudit?.({
+        domain: "git",
+        mutationType: "merge:branch-group-promotion-gated",
+        target: group.id,
+        metadata: {
+          groupId: group.id,
+          branchName: group.branchName,
+          groupAutoMerge: eligibility.groupAutoMerge,
+          effectiveEligible: false,
+          reason: eligibility.reason,
+        },
+      });
+      return {
+        groupId: group.id,
+        promoted: false,
+        alreadyFinalized: false,
+        reason: "gated",
+        status: group.status,
+        prState: group.prState,
+        prNumber: group.prNumber,
+        prUrl: group.prUrl,
+      };
+    }
   }
 
   const integrationBranch = await resolveIntegrationBranch(input.rootDir, input.settings);
-  await ensureGroupBranchExists(input.rootDir, group.branchName, integrationBranch);
-  const currentBranch = (await execAsync("git rev-parse --abbrev-ref HEAD", { cwd: input.rootDir })).stdout.trim();
-  try {
-    await execAsync(`git checkout ${JSON.stringify(integrationBranch)}`, { cwd: input.rootDir });
-    await execAsync(`git merge --no-ff --no-edit ${JSON.stringify(group.branchName)}`, { cwd: input.rootDir });
-  } finally {
-    await execAsync(`git checkout ${JSON.stringify(currentBranch)}`, { cwd: input.rootDir });
+  if (!needsPrRepair) {
+    await ensureGroupBranchExists(input.rootDir, group.branchName, integrationBranch);
+    const currentBranch = (await execAsync("git rev-parse --abbrev-ref HEAD", { cwd: input.rootDir })).stdout.trim();
+    try {
+      await execAsync(`git checkout ${JSON.stringify(integrationBranch)}`, { cwd: input.rootDir });
+      await execAsync(`git merge --no-ff --no-edit ${JSON.stringify(group.branchName)}`, { cwd: input.rootDir });
+    } finally {
+      await execAsync(`git checkout ${JSON.stringify(currentBranch)}`, { cwd: input.rootDir });
+    }
   }
 
-  const isPrMode = input.settings.mergeStrategy === "pull-request";
-
   let prNumber: number | undefined = group.prNumber;
   let prUrl: string | undefined = group.prUrl;
   let prState: BranchGroupPrState = isPrMode ? "open" : "merged";
@@ -342,7 +406,7 @@ export async function promoteBranchGroup(input: {
       groupId: group.id,
       branchName: group.branchName,
       integrationBranch,
-      memberIds: completion.landedMemberIds,
+      memberIds: evaluateBranchGroupCompletion({ members, group }).landedMemberIds,
       ...(updatedGroup.prNumber ? { prNumber: updatedGroup.prNumber } : {}),
       ...(updatedGroup.prUrl ? { prUrl: updatedGroup.prUrl } : {}),
     },
@@ -360,6 +424,68 @@ export async function promoteBranchGroup(input: {
   };
 }
 
+export interface ReconcileBranchGroupPrResult {
+  reconciled: boolean;
+  prState: BranchGroupPrState;
+  prNumber: number | null;
+  prUrl: string | null;
+}
+
+/**
+ * Fix #3 (engine side): out-of-band PR reconciliation primitive.
+ *
+ * Once a branch group finalizes, the member-landing sync stops firing, so nothing
+ * flips `prState` → "merged" after the managed GitHub PR is merged out-of-band.
+ * This helper, given a group carrying a persisted `prNumber` and `prState` "open",
+ * invokes the injected {@link SyncGroupPrFn} (which reconciles against GitHub via
+ * `getPrStatus`) and persists `prState`/`prUrl`/`prNumber` when GitHub reports a
+ * changed state. It mirrors the merger's U6 reconcile block.
+ *
+ * No-op (no write) when the group has no `prNumber`, is not "open", or GitHub still
+ * reports it open. The dashboard route that calls this on a schedule/refresh is
+ * wired in a separate batch; this is just the cleanly exported engine primitive.
+ */
+export async function reconcileBranchGroupPr(input: {
+  store: Pick<TaskStore, "listTasksByBranchGroup" | "updateBranchGroup">;
+  group: BranchGroup;
+  syncGroupPr: SyncGroupPrFn;
+}): Promise<ReconcileBranchGroupPrResult> {
+  const { group } = input;
+  if (group.prNumber == null || group.prState !== "open") {
+    return {
+      reconciled: false,
+      prState: group.prState,
+      prNumber: group.prNumber ?? null,
+      prUrl: group.prUrl ?? null,
+    };
+  }
+
+  const members = await input.store.listTasksByBranchGroup(group.id);
+  const reconciled = await input.syncGroupPr({ group, members });
+
+  if (reconciled.prState === group.prState) {
+    return {
+      reconciled: false,
+      prState: group.prState,
+      prNumber: group.prNumber ?? null,
+      prUrl: group.prUrl ?? null,
+    };
+  }
+
+  const updated = input.store.updateBranchGroup(group.id, {
+    prState: reconciled.prState,
+    prNumber: reconciled.prNumber,
+    prUrl: reconciled.prUrl,
+  });
+
+  return {
+    reconciled: true,
+    prState: updated.prState,
+    prNumber: updated.prNumber ?? null,
+    prUrl: updated.prUrl ?? null,
+  };
+}
+
 export async function resolveBranchGroupMergeRouting(input: {
   task: Pick<Task, "branchContext" | "baseBranch">;
   store: Pick<TaskStore, "getBranchGroup">;
diff --git a/packages/engine/src/index.ts b/packages/engine/src/index.ts
index 7e19eaf2cc..fa187576c7 100644
--- a/packages/engine/src/index.ts
+++ b/packages/engine/src/index.ts
@@ -61,10 +61,13 @@ export {
   evaluateBranchGroupPromotion,
   evaluateBranchGroupCompletion,
   promoteBranchGroup,
+  reconcileBranchGroupPr,
   type BranchGroupMergeRouting,
   type BranchGroupPromotionDecision,
   type BranchGroupCompletionStatus,
   type BranchGroupPromotionResult,
+  type PromoteBranchGroupInput,
+  type ReconcileBranchGroupPrResult,
   type CreateGroupPrFn,
   type SyncGroupPrFn,
   type CloseGroupPrFn,
diff --git a/packages/engine/src/merger.ts b/packages/engine/src/merger.ts
index c5e9613d24..20beb9d7f9 100644
--- a/packages/engine/src/merger.ts
+++ b/packages/engine/src/merger.ts
@@ -82,7 +82,6 @@ import {
   type PostMergeAuditMode,
   type TaskSourceIssue,
   type Task,
-  type BranchGroup,
   type AutostashOrphanRecord,
   normalizeMergeAdvanceAutoSyncMode,
   isMergeRequestContractShadowEnabled,
@@ -7529,34 +7528,28 @@ export async function aiMergeTask(
     // non-fatal and retryable on the next landing / explicit refresh.
     if (options.syncGroupPr) {
       try {
-        const latestGroup = await Promise.resolve(
-          (store as any).getBranchGroup?.(groupRouting.branchGroup.id),
-        ) as BranchGroup | null | undefined;
+        const latestGroup = store.getBranchGroup(groupRouting.branchGroup.id);
         if (latestGroup && latestGroup.prNumber != null && latestGroup.prState === "open") {
-          const members = (await Promise.resolve(
-            (store as any).listTasksByBranchGroup?.(latestGroup.id),
-          )) as Task[] | undefined;
+          const members = await store.listTasksByBranchGroup(latestGroup.id);
           const reconciled = await options.syncGroupPr({
             group: latestGroup,
-            members: members ?? [],
+            members,
           });
           // Out-of-band reconciliation: if GitHub reports the PR is no longer
           // open (closed/merged), persist the corrected prState rather than
           // leaving a stale "open".
           if (reconciled.prState !== latestGroup.prState) {
-            await Promise.resolve(
-              (store as any).updateBranchGroup?.(latestGroup.id, {
-                prState: reconciled.prState,
-                prNumber: reconciled.prNumber,
-                prUrl: reconciled.prUrl,
-              }),
-            );
+            store.updateBranchGroup(latestGroup.id, {
+              prState: reconciled.prState,
+              prNumber: reconciled.prNumber,
+              prUrl: reconciled.prUrl,
+            });
           }
         }
       } catch (err) {
         // Non-fatal: never fail the merge/landing because PR sync failed.
         try {
-          await (store as any).recordRunAuditEvent?.({
+          store.recordRunAuditEvent({
             taskId,
             agentId: "merger",
             runId: `merge-${taskId}`,
diff --git a/packages/engine/src/project-engine.ts b/packages/engine/src/project-engine.ts
index 1f1d3a5365..3918bd19e0 100644
--- a/packages/engine/src/project-engine.ts
+++ b/packages/engine/src/project-engine.ts
@@ -1921,9 +1921,33 @@ export class ProjectEngine {
                 },
               });
             } catch (promotionError) {
+              const message =
+                promotionError instanceof Error ? promotionError.message : String(promotionError);
               runtimeLog.warn(
-                `Branch-group promotion evaluation failed for ${taskId}: ${promotionError instanceof Error ? promotionError.message : String(promotionError)}`,
+                `Branch-group promotion evaluation failed for ${taskId}: ${message}`,
               );
+              // Fix #4 (1): a promotion failure here (e.g. createGroupPr throwing
+              // after the local integration merge) must NOT be swallowed silently —
+              // the group stays active/prState:none and is only recoverable via an
+              // explicit re-promote. Record an audit event so the failure is
+              // observable and operators/the dashboard can drive recovery.
+              try {
+                await store.recordRunAuditEvent({
+                  taskId,
+                  agentId: "merger",
+                  runId: `merge-${taskId}`,
+                  domain: "git",
+                  mutationType: "merge:branch-group-promotion-failed",
+                  target: taskForPromotion.branchContext!.groupId,
+                  metadata: {
+                    groupId: taskForPromotion.branchContext!.groupId,
+                    taskId,
+                    error: message,
+                  },
+                });
+              } catch {
+                // best-effort audit
+              }
             }
           };