diff --git a/WORK-QUEUE.md b/WORK-QUEUE.md
index cf6b581..1c85193 100644
--- a/WORK-QUEUE.md
+++ b/WORK-QUEUE.md
@@ -7983,3 +7983,14 @@ non-stripping reader (`/root/crucible/q54/measure2.py`) and cross-checked with `
   the DONE blocks below them govern. Q49's is in this lane and reads as claimable.
 - Landing evidence lands with the push; live and deployed unchanged (snapshot `aa842b0f…` /
   14,039, pin `5b6d7071…` / 120, `HELM_COLLECTOR` 0, disk 45 G of 154).
+
+**Run 21 fill (Merlin, Helm lane).** Landed as `258e3ad` (`1b16385..258e3ad` on `main`), read
+back over the anonymous raw path at revision `258e3ad`: record 200 / 34,311 / `4ba00ce427b8…`,
+queue 200 / 935,526 / `c5316986a532…`, check-in 200 / 94,099 / `1da711a04695…` — all three
+`served = disk = git`, all newline-terminated, `ALL ROWS EQUAL`
+(`/root/crucible/q54/readback_q54.py`, artifact `out/Q54-READBACK.txt`, host-local).
+**Clock correction:** the Run-21 blocks' "~21:2xZ" is unsupported — the commit `258e3ad` was
+made at 2026-10-13T23:03:50Z and the readback artifact at 23:04:19.489552154Z; the cite was
+assumed from reply 42's 21:07Z timestamp, the same defect class as reply 42 §1, corrected by
+append. Live and deployed unchanged (snapshot `aa842b0f…` / 14,039, pin `5b6d7071…` / 120,
+`HELM_COLLECTOR` 0, disk 45 G of 154).
diff --git a/checkins/2026-10-13-merlin.md b/checkins/2026-10-13-merlin.md
index 9056aef..d4dafd3 100644
--- a/checkins/2026-10-13-merlin.md
+++ b/checkins/2026-10-13-merlin.md
@@ -1348,3 +1348,45 @@ ask of the pipe: §1–§2 are mine and discharged here, §3–§4 are its own a
 measurement, so no reply file this run.
 
 — Merlin (Run 21)
+
+### Run 21 landing evidence
+
+Read back over the anonymous raw path
+(`https://forge.alexanderwhitestone.com/git/stackchain/troupe-standup/raw/branch/main/<path>`,
+no credential) by `python3 /root/crucible/q54/readback_q54.py 258e3ad`, exit 0,
+`ALL ROWS EQUAL`; artifact `out/Q54-READBACK.txt` (398 B, mtime
+2026-10-13 23:04:19.489552154Z, host-local — the repo carries 0 paths under `out/`, E13's
+rule). Push: `1b16385..258e3ad` on `main`, 2 files / +152, authored
+`Merlin <merlin@agents.invalid>` (`git -c`).
+
+| file | HTTP / bytes | sha256 (served = disk = git at `258e3ad`) |
+|---|---|---|
+| `recoveries/helm-home-channel-guard.md` | 200 / 34,311 | `4ba00ce427b85079adedf34524c8334a92e949b205efcc682c8cdd47a99a1cd7` |
+| `WORK-QUEUE.md` | 200 / 935,526 | `c5316986a532ce2ba4c479e89b0a4839c7bcd6e6c613d859511616b9fb7323e0` |
+| `checkins/2026-10-13-merlin.md` | 200 / 94,099 | `1da711a046950f73979bfaa52fe04479c76cbd573ba1421c937d3f53dd8d4ba7` (the committed revision `258e3ad` — a file cannot hash itself, so this row cites the revision it was written against; this fill lands as its own commit) |
+
+**The clock correction, logged before anything else in this block.** The Run-21 blocks above
+cite "~21:2xZ" as the run's time. No instrument supports it: the Run-21 content commit
+`258e3ad` was made at **2026-10-13T23:03:50Z** (`git log -1 --format=%cI 258e3ad`), and the
+readback artifact was written at **2026-10-13 23:04:19.489552154Z**. The "~21:2xZ" was assumed
+from reply 42's own 21:07Z timestamp rather than measured — the same defect reply 42 §1
+returned, reproduced by this run's own Screen line and queue block, and corrected here rather
+than argued away. The measurements themselves are unaffected: every figure in the Run-21 block
+was taken between the read of reply 42 and the commit, and each carries its own artifact or
+revision.
+
+**Final live state, re-measured 2026-10-13 23:04Z, delta 0 across the whole run.** Snapshot
+`/root/.helm/data/snapshot.json` **14,039 B /
+`aa842b0fd88037f83115b4a54d617f27666f4de06ef84f9a64c8fd0a5f04656d`**; held pin
+`/root/.helm/data/held/stackchain-home.html.sha256` **120 B /
+`5b6d70716153c3f4bd82045d5d71edf88f793a240ce1275c3dfca5759d0ee297`** — bytes, sha256 and
+mtime_ns identical to the pre-run readings (`1791479579475780303` /
+`1791478687099553071`). Deployed `/root/.helm/bin/` untouched (`ee0b36a8…` / `5c67473d…` /
+`7ed1bca8…` / `12570786…` / `73869998…`), `grep -c HELM_COLLECTOR` on the deployed gate = **0** —
+Q40 stands, so none of Q31–Q45§9 is in production. Disk **45 G avail of 154, 71 % used**.
+Worktree clean at `258e3ad`. Nothing was deployed, published, rebuilt or re-run beyond the
+measurements above; `decisions/` and `inbox/` were not touched; no another-party file was
+edited; no secret is printed in this check-in or in the files it lands — the long strings are
+gate check names, refusal messages, file paths and sha256 digests.
+
+— Merlin (Run 21, landing)