feat(pair-corpus-honesty): add vibe-py, vfc-js and agent-vfc slices with mechanism vocabulary

Tasks 1.1, 5.1, 5.2, 5.4 and the data half of 5.3.

- mechanisms.toml: closed vocabulary v1 (20 ids) every expected row cites.
- vibe-py: 35 Real-Vuln-Benchmark pairs (Apache-2.0), human provenance only
  because the LLM-generated repositories carry no license (escalated).
- vfc-js: 17 Node fix-commit pairs harvested upstream (MIT/Apache-2.0),
  SecBench.js itself is not vendored (no license); sinks derived on 13/17.
- agent-vfc: 29 agent-trailer fixes as catalog-candidates.toml plus
  REVIEW.md; the loaded catalog stays empty until a human reviews them.
- datasets.toml and README document every slice and its review status.

Co-Authored-By: Claude Fable 5.1 <[email protected]>
Claude-Session: https://claude.ai/code/session_01T7XD7x5KonMdmGRkp63EQG

benchmarks/pairs/agent-vfc/popmark-editorconfig-e5ac40/fixed.ts

@@ -0,0 +1,33 @@
+// Provenance: dayflower/popmark  (fixed).
+// repo: dayflower/popmark
+// commit: e5ac407cef37c37178d440541ede301c838640fb
+// parent: 31d1ac79b4cfa3118597348e79800a6561115149
+// commit_url: https://github.com/dayflower/popmark/commit/e5ac407cef37c37178d440541ede301c838640fb
+// cve: 
+// license: MIT
+// function: deepMergeInto
+// relpath: src/lexical-markdown/config/editorConfig.ts
+// provenance: agent
+// mechanism: prototype_pollution
+
+function deepMergeInto(
+  target: Record<string, unknown>,
+  source: Record<string, unknown>,
+): Record<string, unknown> {
+  for (const key of Object.keys(source)) {
+    // popmark patch: guard against prototype pollution (CodeQL).
+    if (key === "__proto__" || key === "constructor" || key === "prototype") {
+      continue;
+    }
+    const sourceValue = source[key];
+    if (sourceValue === undefined) continue;
+    if (isPlainObject(sourceValue)) {
+      const targetValue = target[key];
+      const nested = isPlainObject(targetValue) ? targetValue : {};
+      target[key] = deepMergeInto(nested, sourceValue);
+    } else {
+      target[key] = sourceValue;
+    }
+  }
+  return target;
+}

benchmarks/pairs/agent-vfc/popmark-editorconfig-e5ac40/vuln.ts

@@ -0,0 +1,29 @@
+// Provenance: dayflower/popmark  (vuln).
+// repo: dayflower/popmark
+// commit: 31d1ac79b4cfa3118597348e79800a6561115149
+// parent: 31d1ac79b4cfa3118597348e79800a6561115149
+// commit_url: https://github.com/dayflower/popmark/commit/e5ac407cef37c37178d440541ede301c838640fb
+// cve: 
+// license: MIT
+// function: deepMergeInto
+// relpath: src/lexical-markdown/config/editorConfig.ts
+// provenance: agent
+// mechanism: prototype_pollution
+
+function deepMergeInto(
+  target: Record<string, unknown>,
+  source: Record<string, unknown>,
+): Record<string, unknown> {
+  for (const key of Object.keys(source)) {
+    const sourceValue = source[key];
+    if (sourceValue === undefined) continue;
+    if (isPlainObject(sourceValue)) {
+      const targetValue = target[key];
+      const nested = isPlainObject(targetValue) ? targetValue : {};
+      target[key] = deepMergeInto(nested, sourceValue);
+    } else {
+      target[key] = sourceValue;
+    }
+  }
+  return target;
+}