review(5): note current V6 matrix frontier

machine-docs/REVIEW-5.md

@@ -299,3 +299,36 @@ rely on the older A5-4 snapshot alone.
 **Verdict:** A5-4 is no longer reproducible on the current live bridge flow. The stale-test/default path
 for `matrix-synapse` now exposes an in-flight status and a terminal failure status on the recipe PR head,
 and `testme-on-pr.sh` reads the verdict back correctly.
+
+---
+
+## Current-frontier review note — 2026-06-01T19:00:00Z
+
+No `Gate: <Mn> CLAIMED` was pending in `STATUS-5.md`. I re-oriented from the current live frontier rather
+than the older closed findings.
+
+### Matrix-synapse V5/V6 frontier: current live state
+- Builder `STATUS-5.md` has **not** yet been refreshed to reflect the later rerun/build `#63` or any V6
+  cc-ci-side branch/PR state, so I treated live Git/Gitea state as authoritative for this pass.
+- Live recipe PR state for `recipe-maintainers/matrix-synapse#1` remains:
+  - `state=open`, `merged=false`, head `21e5d84430bdc52f8fa8aa9a40fa5bda8adf06c0`
+  - latest result comment is the terminal failure card for build `#63`
+  - head commit status is `cc-ci/testme state=failure target_url=.../63`
+- There is **no** new open cc-ci PR yet for the V6 `--with-tests` path. The only visible cc-ci-side V6
+  artifact is remote branch `origin/v6-matrix-synapse-real-upgrade-state`.
+
+### Branch review: V6 test direction looks materially stronger, but is not yet cold-verified end-to-end
+- I inspected the current V6 branch diff against `origin/main`.
+- The branch replaces the previous synthetic upgrade assertion (`SELECT v FROM ci_marker`) with a real
+  Matrix application-data continuity probe:
+  - pre-upgrade: create two Matrix users via Synapse admin registration, create a room, send a message,
+    and persist only minimal metadata to `/data/ccci-upgrade-state.json`
+  - post-upgrade: log in as the second user and verify the pre-upgrade message is still readable from the
+    same room through the Matrix client API
+- This is directionally correct for V6 because it tests real app state instead of a cc-ci-only postgres
+  marker table.
+
+**Verdict:** no new live defect to file from this frontier check. But V6 is **not yet adversary-verified**:
+there is no cc-ci test PR, no paired cross-note evidence, and no cold `verify-pr.sh` result yet. The next
+useful adversary action is to verify that live `--with-tests` flow once the Builder exposes a real cc-ci
+test PR / branch-checkout run.