docs(release-process): add post-fix repro verification policy

Race-condition and concurrency fixes must include reporter-verified repro confirmation before the originating issue is closed. Adds the checklist and rationale grounded in recent incident examples.

Closes MEDIUM-12

docs/reference/release-process.md

@@ -12,33 +12,19 @@ Before publishing a release, maintainers verify:
 - User-facing documentation covers new public behavior.
 - Known issues are documented before the release notes are finalized.
 
-CI green is required for release readiness, but CI does not replace manual
+CI green is required for release readiness, but CI does not replace manual verification for bugs whose reproducer depends on timing, providers, models, or external OpenCode behavior.
-verification for bugs whose reproducer depends on timing, providers, models, or
-external OpenCode behavior.
 
 ## Post-Fix Repro Verification
 
-### Policy
+Race-condition and concurrency fixes must include reporter-verified repro confirmation before the originating issue is closed. CI green is necessary but not sufficient for this class of fix.
-
-For race-condition and concurrency fixes, the original issue reporter, or a
-maintainer if the reporter is unavailable, must re-run the documented
-reproducer against the fix commit before the issue is closed. CI green is
-necessary but not sufficient.
 
 ### Checklist
 
-- [ ] Reproducer documented in the issue thread with steps, expected result,
+- [ ] Original issue reporter (or maintainer if reporter unavailable) re-runs the documented reproducer against the fix commit.
-  and actual result.
+- [ ] Re-run result documented in the issue thread as "Repro retested: PASS/FAIL on commit <SHA>".
-- [ ] Fix commit identified.
+- [ ] If repro is environmental (specific OS, model, provider), repro is attempted in matching environment.
-- [ ] Reproducer re-run on the fix commit.
+- [ ] If repro cannot be obtained, this is explicitly noted in the issue close comment AND recorded in release notes as "Fix unverified end-to-end".
-- [ ] Result documented in the issue thread as
-  "Repro retested: PASS on <commit-sha>".
-- [ ] If the repro is environmental, such as a specific OS, model, or provider,
-  the re-run is attempted in matching conditions.
 
-### Escalation
+### Rationale
 
-If the repro cannot be obtained, such as a transient race that does not
+Race-condition fixes that pass CI but were never retested against the original reproducer have historically regressed in production. Issues #4006, #3996, #3962 are recent examples where reporter confirmation was sparse. Issue #4012 (the prompt-async-gate motivating bug) had detailed reporter analysis that drove the eventual fix, and that level of post-fix verification should be the norm for this class.
-reproduce locally, the limitation must be noted in the issue close comment and
-added to release notes as "Fix unverified end-to-end". Do not close the issue
-as fully verified without that disclosure.