Remove unused captured state and orphan helpers

docs/roadmap/implementation.md

@@ -779,6 +779,11 @@ tests and one-iteration checks of both benchmark paths pass on Go 1.27.3.
 discovery and identity/listing behavior remain covered. Optional public helpers,
 capability fallbacks, and embedded/release assets are not deletion candidates.
 
+Completion: unused backend presence and queue bookkeeping, the reachability
+endpoint echo, and the named orphan helpers were removed after caller checks.
+Queue, provenance, reachability, identity, discovery, and related public tests
+pass on Go 1.27.3. The remaining file-source caller uses its three results.
+
 ## Stage 31: Remove Redundant Captured Prompt Fields
 
 **Catalog:** 31. **Files:** domain prompt values, configuration capture, runner/fixtures.