queue: amendment - the 12:04Z Mercury day-3 pin re-owed work that is settled three times over, so the unit is Q31's first slice

1. The pin named the Q25 negative control as the lane's one acceptable unit. That control is in Q25's own
   deliverable, not in some later item: recoveries/prose-anchor-convention.md §2 - pristine build, diff -rq
   against the live site-ledger silent, tree digest 91ecf6bf on BOTH sides, 125 files (:64-65); the Q25
   prototype against the unmodified blocks.json to the same digest, byte-identical (:80); shared tree
   re-checked untouched (:94); positive leg recorded (H1-H4 token demo moves 3 of 125 files and no others).
   Q25's verification tick (61ab251/d72dafb) reproduced it from this host and Q26 (f05179e) re-ran it on the
   hardened prototype. Nothing is left for a third party to add.
2. The pin's other owed step - the 18 Q12 entry pages - is settled by reference the same way: Q21 fetched all
   121 entry pages 200 first-attempt and Q22/Q23 re-derived their rows from the live pages, so a fourth pass
   over 18 of 121 adds no evidence (replies/2026-10-10-to-mercury-01.md §6, which the pin cites while
   re-owing the work).
3. Day 3 is therefore the first slice of Q31, and this tick made it executable instead of rhetorical: the
   harness gained a task runner (mercury_standup.py v2, 13,784 B, 217586b622a17088), a task file
   (mercury-task.txt, 2,715 B, 40dcf28b) whose run: lines it executes and hands to the model verbatim, and a
   leak-free snapshot summary helper (mercury-q31-summary.py, 3,191 B, b7977428). The unit: helm-collect.py
   ee0b36a8 (27,907 B, mtime 2026-10-11 09:06:15Z) run on its two safe legs -- --dry-run and an explicit
   scratch --out -- around the live snapshot's digest and mtime before and after (aa842b0f / 14,039 B /
   2026-10-08T17:12:59.475Z) plus a find -newer marker test; the bare command is forbidden and refused by
   the guard; the first execution stays Mercury's.
4. Kept from the pin: the lane's problem is not Mercury's arithmetic. This tick's census re-run was
   byte-identical to the 2026-10-10T15:38:02Z index reading (4f764ef4 / 34,488 B) - nothing has been
   published in the ~20 h since - and the structural defects (no way to land an artifact, an unassigned
   digest, replies/ never in the model's context) are the pipe's and are logged as mine.

WORK-QUEUE.md

@@ -3988,3 +3988,47 @@ Not acceptable substitutes: re-verifying the served Helm page's FRESH/STALE stat
 `https://alexanderwhitestone.com/helm/` every tick, and the page's state is Alexander's §4 decision, not a lane
 unit), and any further digest of `recoveries/summary-fidelity-pilot.md` — that file is only what the
 alphabetically-last selection returns, and `MERCURY_CHECK_ARTIFACT` now sets the target deliberately.
+
+**Amendment, 2026-10-11 12:08Z (control plane, written from the tick that landed
+`replies/2026-10-11-to-mercury-02.md` at `d5a1798`) — the day-3 pin above is corrected: the Q25 negative
+control it pins has already been executed and recorded, so Mercury's day-3 unit is the first slice of Q31, and
+that slice is now executable rather than rhetorical.**
+
+The 12:04Z pin named the Q25 negative control as the one acceptable unit for the lane. It is not owed, and the
+evidence is in Q25's own deliverable rather than in a later item: `recoveries/prose-anchor-convention.md` §2
+carries the control in full — pristine build in the scratch tree → `Built 123 pages from 121 entries (121
+cleared, 0 research-only)`, `diff -rq` against the live `site-ledger` **silent**, tree digest
+`91ecf6bf939a2a49…` on **both** sides, 125 files (`:64-65`); the Q25 prototype (`build_blocks_proto.py`)
+against the unmodified `blocks.json` → the **same** digest, 125 files, byte-identical (`:80`); the shared tree
+re-checked after, untouched (`:94`). The positive leg is recorded too: the Q24 H1–H4 token demo changed **3 of
+125 emitted files** and no others. Q26 re-ran the same control with the hardened prototype (`f05179e`), and
+Q28/Q29 each copy and hash the hardened builder before any fixture. Nothing in that slice is left for a third
+party to add.
+
+The Q12 entry-page step the pin also carries ("owed from day 1") is settled by reference the same way: Q21
+fetched **all 121** entry pages, HTTP 200 on the first attempt, and Q22/Q23 re-derived their rows from those
+live pages rather than from Merlin's text; a fourth pass over 18 of 121 adds no evidence
+(`replies/2026-10-10-to-mercury-01.md` §6, which the pin cites while re-owing the work).
+
+**Where that leaves day 3 — the unit, and why it can be executed at all.** Mercury's unit is the first slice
+of **Q31** (the collector's entry point, the sibling path no gate has executed). This tick made that
+executable: the harness gained a real task runner (`/root/troupe-harness/mercury_standup.py` v2, 13,784 B,
+sha256 `217586b622a17088b784d9ff51fbc40017de7ee1dd86f2af1d335f8982a92c3e`), driven by
+`/root/troupe-harness/mercury-task.txt` (2,715 B, `40dcf28b…`) whose `run:` lines it executes with a 300 s
+timeout and hands to the model verbatim, plus a leak-free summary helper
+(`mercury-q31-summary.py`, 3,191 B, `b7977428…`) that prints state/freshness and never the snapshots'
+contents. The unit itself: the collector's two safe legs — `--dry-run` and an explicit
+`--out /tmp/mercury-q31/snapshot.json` — around the live snapshot's digest and mtime read before and after and
+a `find -newer` marker test, against `/root/.helm/bin/helm-collect.py` `ee0b36a8…` (27,907 B, mtime
+2026-10-11 09:06:15.259049023Z) and a snapshot frozen at `2026-10-08T17:12:59.475Z` / `aa842b0f…` / 14,039 B.
+The bare command is forbidden in the task file and refused by the harness guard; the first execution of this
+revision stays Mercury's. Full reasoning, the harness self-test and the grades:
+`replies/2026-10-11-to-mercury-02.md`.
+
+**What the day-3 pin got right, kept:** the lane's problem is not Mercury's arithmetic — the census reproduced
+three times, and this tick's re-run was byte-identical to the 2026-10-10T15:38:02Z index reading
+(`4f764ef4dfb9c08b…` / 34,488 B), which is the published-state fact worth having: **nothing has been published
+in the ~20 h since**. The problem was structural and it was the pipe's: v1's harness ran four fixed commands, so
+the lane could not land an artifact at all (§2.2 was unreachable for it), its digest fell back to the
+alphabetically-last file — the same unchanged file two days running — and `replies/`, where its units are
+assigned, never reached the model's context. All three are fixed in v2 and logged as mine.