Add shared-engine calibration-only relevance diagnostics

docs/ROADMAP.md

@@ -235,6 +235,12 @@ Completion requires recorded evidence; targets are not measured results.
     returned candidates. See [mixed quality](MIXED-QUALITY.md).
   - [ ] Measure task fusion and cache cost against independently reviewed
     held-out data, preserving the frozen diagnostic for regression comparison.
+    - [x] Freeze disjoint bilingual text/code calibration and held-out labels
+      after independent AI review; verify exact Git-preserved source/label bytes.
+    - [x] Add a shared-engine calibration-only runner retaining raw cosine,
+      lexical provenance, hybrid ranks and atomic incomplete evidence.
+    - [ ] Execute calibration, freeze the proposed relevance policy, then
+      evaluate held-out queries without tuning against their results.
   - [x] Explicit English/German code intent vetoes exclusive audio routing;
     actual Google CPU regression preserves code among qualifying audio candidates.
 - [ ] Validate code search UI interaction on native Windows/macOS/Linux and