diff --git a/scripts/check-rank-feedback.mjs b/scripts/check-rank-feedback.mjs
index 6d75c6b..68ae05d 100644
--- a/scripts/check-rank-feedback.mjs
+++ b/scripts/check-rank-feedback.mjs
@@ -177,6 +177,32 @@ try {
   assert.equal(hardRail.brief.quickGlance.topPick, 'Manual source-traced build order preview');
   assert.equal(hardRail.handoff.readiness.status, 'ready');
 
+  const duplicateTraceResponse = await fetch(`${base}/api/rank-feedback`, {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify({
+      schema: 'prioritix-feature-set-v1',
+      sourceName: 'Scattermind',
+      artifactId: 'concept_map_duplicate_trace',
+      snapshotTitle: 'Duplicate source trace handoff',
+      originalPrompt: 'Clarify a bridge handoff while preserving source trace identity.',
+      idea: 'Scattermind clarified two different continuation moves from one Concept Map source block.',
+      mode: 'mvp',
+      featureSet: {
+        features: [
+          { id: 'active-copy-slice', title: 'Active copyable build slice', description: 'Show one defended action with source trace.', evidenceNeeded: 'Can a tired builder act on the copied slice?', sourceSection: 'concept-map.nextActions', sourceItemId: 'next-actions#1', rankerHints: { value: 8, effort: 2, confidence: 7, urgency: 7, risk: 2 } },
+          { id: 'manual-proof-script', title: 'Manual proof script', description: 'Turn the active slice into one script for a real proof conversation.', evidenceNeeded: 'Does the script produce a yes/no signal?', sourceSection: 'concept-map.nextActions', sourceItemId: 'next-actions#1', rankerHints: { value: 7, effort: 2, confidence: 7, urgency: 6, risk: 2 } },
+          { id: 'later-dashboard', title: 'Saved result dashboard', description: 'Accounts and saved workspaces for every result.', recommendedLane: 'defer', sourceSection: 'concept-map.deferred', sourceItemId: 'deferred#1' },
+        ],
+      },
+    }),
+  });
+  assert.equal(duplicateTraceResponse.status, 200);
+  const duplicateTrace = await duplicateTraceResponse.json();
+  assert.ok(duplicateTrace.handoff.warnings.some(item => /duplicate source id next-actions#1 used by active-copy-slice and manual-proof-script/.test(item)), 'duplicate source trace IDs should be surfaced for bridge consumers');
+  assert.equal(duplicateTrace.handoff.readiness.status, 'usable-with-warnings');
+  assert.ok(duplicateTrace.handoff.readiness.nextChecks.some(item => /duplicate IDs/i.test(item)));
+
   const softGuardrailResponse = await fetch(`${base}/api/rank-feedback`, {
     method: 'POST',
     headers: { 'Content-Type': 'application/json' },
diff --git a/server.js b/server.js
index 143bf36..f10a051 100644
--- a/server.js
+++ b/server.js
@@ -2049,12 +2049,21 @@ function copyableHandoffText({ ranked = [], provenance = {}, decisionContext = {
 function createHandoffContract({ ranked, provenance, decisionContext }) {
   const warnings = [];
   const expectsSourceTrace = Boolean(provenance?.artifactId || provenance?.conceptMapId || provenance?.snapshotTitle);
+  const seenSourceIds = new Map();
   if (!provenance?.artifactId && provenance?.originalPrompt) warnings.push('missing source artifact id');
   if (expectsSourceTrace && !provenance?.originalPrompt && !provenance?.sourceSummary) warnings.push('missing source context provenance');
 
   const itemTrace = ranked.map(item => {
-    if (expectsSourceTrace && !item.provenance?.sourceSection) warnings.push(`missing source section for ${item.id}`);
+    const sourceId = cleanText(item.provenance?.sourceId || '', 120);
+    const sourceSection = cleanText(item.provenance?.sourceSection || '', 80);
+    const traceKey = sourceId && sourceSection ? `${sourceSection}::${sourceId}` : sourceId;
+    if (expectsSourceTrace && !sourceSection) warnings.push(`missing source section for ${item.id}`);
     if (item.provenance?.idNormalized) warnings.push(`duplicate source id ${item.provenance.originalId} normalized to ${item.id}`);
+    if (expectsSourceTrace && traceKey) {
+      const firstItemId = seenSourceIds.get(traceKey);
+      if (firstItemId && firstItemId !== item.id) warnings.push(`duplicate source id ${sourceId} used by ${firstItemId} and ${item.id}`);
+      else seenSourceIds.set(traceKey, item.id);
+    }
     if (expectsSourceTrace && !item.factors?.evidenceNeeded && ['do', 'test'].includes(item.lane?.id)) warnings.push(`missing evidence needed for active item ${item.id}`);
     if (item.metrics?.nonGoalConflicts?.length && ['do', 'test'].includes(item.lane?.id)) warnings.push(`active item ${item.id} conflicts with source non-goals: ${item.metrics.nonGoalConflicts.join('; ')}`);
     return {