docs(remediation): bank D-8 — a pre-registered check that was not runnable as written

PR #1025's AC2 fixture (mkdir -p apps/*/venv/lib) does not do what it claims when the
glob is unmatched. rev-974 ran it exactly as written, caught the defect, re-ran the
intended assertion at an explicit path, and DISCLOSED the substitution rather than
silently reporting PASS.

Pre-registration protects a check from being retrofitted to the implementation. It
does not make the check correct. An unverified gate appeared inside the mechanism
built to catch unverified gates.

Requirement added to RM-02: the registry must self-verify that every registered case
actually runs and can actually fail — presence in the registry is not evidence.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

docs/remediation/TASKS.md

@@ -93,6 +93,32 @@ and must not be cited as merge evidence. Rely on reviewer clearance + real CI.
 Three independent live instances in a single session — format gate, agent context reset, queue guard —
 is the class confirmed, not anecdote.
 
+### D-8 — a PRE-REGISTERED acceptance check that was not runnable as written
+
+On PR #1025 the author (me) pre-registered AC2 with the fixture snippet `mkdir -p apps/*/venv/lib`.
+In bash, when no `venv` exists the glob is unmatched and passes through literally, creating a
+directory named `apps/*/venv/lib` rather than one per workspace. The check as written did not test
+what it claimed to test.
+
+`rev-974` ran it **exactly as written**, observed the wrong behaviour, then re-ran the intended
+assertion at an explicit path — **and said so in the review** rather than silently substituting a
+working fixture and reporting PASS.
+
+Two things this establishes:
+
+1. **The instruction "do not adjust a check to fit the diff; if it is unrunnable, say so explicitly"
+   worked.** A silent substitution here would have produced a green AC2 that proved nothing, on the
+   exact task whose subject is gates that appear to work. The disclosure is what made the PASS
+   meaningful.
+2. **Pre-registration does not confer correctness.** A pre-registered check is protected from being
+   retrofitted to the implementation; it is not protected from being _wrong when written_. This is a
+   small instance of the mission's own class — an unverified gate — occurring inside the mechanism
+   built to catch unverified gates.
+
+**Requirement on RM-02:** the gate registry must itself be exercised. A registered case that cannot
+fail (or cannot run) is as inert as an unregistered one, and the registry check must detect that —
+`--dry-run`-style self-verification of every registered case, not merely its presence.
+
 ### D-7 — shared-tmpfs contention → cascading ENOSPC (live incident, 2026-07-31)
 
 The shared 30 G `/tmp` hit **100% ENOSPC** mid-session. It broke tool calls in **two different seats**