FN-5764: expose mission assertion backfill through API and CLI

Expose mission assertion backfill controls and run paths across engine, API, and CLI surfaces.

- add mission assertion backfill gating classification and reliability coverage for assertion-linked validation recovery
- add dashboard mission routes plus legacy API coverage and e2e checks for running assertion backfill
- expose new extension tool support and update Fusion skill docs/capability references
- add a changeset for @runfusion/fusion and refresh mission documentation

Files changed:
 .changeset/fn-5764-mission-backfill-assertions.md  |   9 ++
 docs/missions-completion-contract.md               |   7 +-
 docs/missions.md                                   |   7 +-
 packages/cli/skill/fusion/SKILL.md                 |   2 +-
 .../cli/skill/fusion/references/extension-tools.md |   9 ++
 .../skill/fusion/references/fusion-capabilities.md |   1 +
 packages/cli/src/__tests__/extension.test.ts       |  41 +++++++
 packages/cli/src/extension.ts                      |  43 +++++++
 .../dashboard/app/__tests__/api-missions.test.ts   |  44 +++++++
 packages/dashboard/app/api/legacy.ts               |  34 ++++++
 .../dashboard/src/__tests__/mission-e2e.test.ts    | 127 +++++++++++++++++++++
 packages/dashboard/src/mission-routes.ts           |  29 +++++
 .../mission-validation-trigger-gap.test.ts         |  66 +++++++++++
 .../workflow-step-readonly-allowlist.test.ts       |   1 +
 packages/engine/src/gating-classifications.ts      |   1 +
 15 files changed, 418 insertions(+), 3 deletions(-)

Fusion-Task-Id: FN-5764

Fusion-Task-Lineage: b16123c2-7cfe-4b17-a899-4e30044a7a49

packages/engine/src/__tests__/reliability-interactions/mission-validation-trigger-gap.test.ts

@@ -237,4 +237,70 @@ describe("FN-5715 reliability: mission validation trigger gap", () => {
     expect(noAssertionEvents).toHaveLength(1);
     loop.stop();
   });
+
+  it("routes through validator after assertion backfill instead of no-assertion auto-pass", async () => {
+    const feature = makeFeature({ status: "done", acceptanceCriteria: "must pass", loopState: "implementing" });
+    const currentFeature = { ...feature };
+    const linkedAssertions: Array<{ id: string }> = [];
+
+    const missionStore = {
+      listMissions: vi.fn(() => [{ id: "M-001", status: "active" }]),
+      getMissionWithHierarchy: vi.fn(() => ({
+        id: "M-001",
+        status: "active",
+        milestones: [{ status: "active", slices: [{ status: "active", features: [feature] }] }],
+      })),
+      getFeatureByTaskId: vi.fn(() => currentFeature),
+      getFeature: vi.fn(() => currentFeature),
+      updateFeatureStatus: vi.fn((_featureId: string, status: "done") => ({ ...currentFeature, status })),
+      updateFeature: vi.fn((_featureId: string, patch: Partial<MissionFeature>) => {
+        Object.assign(currentFeature, patch);
+        return { ...currentFeature };
+      }),
+      listAssertionsForFeature: vi.fn(() => linkedAssertions),
+      startValidatorRun: vi.fn(() => ({ id: "VR-001", featureId: "F-001" })),
+      completeValidatorRun: vi.fn(),
+      getSlice: vi.fn(() => ({ id: "SL-001", milestoneId: "MS-001", status: "active" })),
+      getMilestone: vi.fn(() => ({ id: "MS-001", missionId: "M-001" })),
+      logMissionEvent: vi.fn(),
+      transitionLoopState: vi.fn(),
+      setFeatureCurrentTaskRunId: vi.fn(),
+      getFailuresForRun: vi.fn(() => []),
+    };
+    const taskStore = {
+      getTask: vi.fn(async () => ({ id: "FN-001", column: "done", status: "done" })),
+      on: vi.fn(),
+      off: vi.fn(),
+    };
+
+    const loop = new MissionExecutionLoop({ missionStore: missionStore as any, taskStore: taskStore as any, rootDir: process.cwd() });
+    vi.spyOn(loop as any, "runValidation").mockResolvedValue({ status: "pass", summary: "ok" });
+    loop.start();
+
+    await loop.recoverActiveMissions();
+
+    const noAssertionEventsBefore = missionStore.logMissionEvent.mock.calls.filter(
+      ([, type, , payload]) => type === "warning" && payload?.code === "validation_auto_passed_no_assertions",
+    );
+    expect(noAssertionEventsBefore).toHaveLength(1);
+    expect(missionStore.startValidatorRun).not.toHaveBeenCalled();
+
+    linkedAssertions.push({ id: "CA-001" });
+    currentFeature.loopState = "implementing";
+    currentFeature.lastValidatorStatus = undefined;
+
+    await loop.processTaskOutcome("FN-001");
+
+    expect(missionStore.startValidatorRun).toHaveBeenCalledWith("F-001", "task_completion");
+    const noAssertionEventsAfter = missionStore.logMissionEvent.mock.calls.filter(
+      ([, type, , payload]) => type === "warning" && payload?.code === "validation_auto_passed_no_assertions",
+    );
+    expect(noAssertionEventsAfter).toHaveLength(1);
+    expect(missionStore.updateFeature).toHaveBeenCalledWith(
+      "F-001",
+      expect.objectContaining({ loopState: "passed", lastValidatorStatus: "passed" }),
+    );
+
+    loop.stop();
+  });
 });

packages/engine/src/__tests__/workflow-step-readonly-allowlist.test.ts

@@ -43,6 +43,7 @@ describe("workflow-step readonly allowlist policy", () => {
       "fn_mission_create",
       "fn_mission_delete",
       "fn_mission_update",
+      "fn_mission_backfill_assertions",
       "fn_milestone_add",
       "fn_slice_add",
       "fn_feature_add",

packages/engine/src/gating-classifications.ts

@@ -30,6 +30,7 @@ const PERMANENT_TASK_AGENT_ONLY_TOOLS = [
   "fn_mission_create",
   "fn_mission_delete",
   "fn_mission_update",
+  "fn_mission_backfill_assertions",
   "fn_milestone_add",
   "fn_slice_add",
   "fn_feature_add",