feat(FN-5321): add evidence gap detector for external integration manifests

Implements external integration validation (FN-5321) with a manifest validator scaffold, worktrunk manifest wiring, and an evidence gap detector that runs during spec validation and triage; the reviewer also gates on external integration readiness. Includes tests for manifest, evidence gap, and tria

Fusion-Task-Id: FN-5321

packages/engine/src/triage.ts

@@ -36,6 +36,10 @@ import {
 } from "./agent-session-helpers.js";
 import { reviewStep, type ReviewVerdict } from "./reviewer.js";
 import { detectDanglingTaskDocReferences, formatDanglingDiagnostic } from "./spec-validation/task-document-references.js";
+import {
+  detectExternalIntegrationEvidenceGaps,
+  formatExternalIntegrationEvidenceDiagnostic,
+} from "./spec-validation/external-integration-evidence.js";
 import { buildSessionSkillContext } from "./session-skill-context.js";
 import { PRIORITY_SPECIFY, type AgentSemaphore } from "./concurrency.js";
 import { AgentLogger } from "./agent-logger.js";
@@ -2101,6 +2105,20 @@ export class TriageProcessor {
             };
           }
 
+          const evidenceGaps = detectExternalIntegrationEvidenceGaps({
+            promptContent,
+          });
+          if (evidenceGaps.length > 0) {
+            const diagnostic = formatExternalIntegrationEvidenceDiagnostic(evidenceGaps);
+            specReviewVerdictRef.current = "REVISE";
+            planLog.warn(`${taskId}: ${diagnostic}`);
+            await store.logEntry(taskId, "Spec review: REVISE (external-integration evidence gaps)");
+            return {
+              content: [{ type: "text" as const, text: diagnostic }],
+              details: {},
+            };
+          }
+
           // Re-read task detail to get latest user comments
           const currentDetail = await store.getTask(taskId);
           const currentUserComments = (currentDetail.comments || []).filter(