journal: gc.1 — append cadence-flow notes 3+4 from first real grounding-check run

Note 3: agent output format leaked internal-thinking preamble before
the structured report block — Iron Law should forbid preamble.
Note 4: Boss-requested behaviour change for impending-BLOCK paths —
on miss, agent attempts to write missing GREEN test (test code only,
never src/) before falling to BLOCK; requires tool + Iron Law update.
Both notes are for the future skillsystem-postmortem entry; out of
gc.1 scope.

docs/journals/2026-05-11-iter-gc.1.md

@@ -89,6 +89,26 @@ for gc.1 itself:
    here so it is not misread, in retrospect, as evidence that the
    phases are too lenient.
 
+3. **First real run of grounding-check (2026-05-11 same-day, on
+   the revised Spec-23): PASS, 15 assumptions ratified.** The
+   agent's output format leaked an internal-thinking preamble
+   before the structured `GROUNDING-CHECK REPORT` block — the
+   Iron Law should be tightened to forbid any preamble before the
+   structured report. Substantively unproblematic (the judgement
+   and test pins were clear) but a real prompt-discipline gap.
+
+4. **Behaviour change requested for impending-BLOCK paths.** On a
+   miss (assumption with no green test), the agent should attempt
+   to write the missing GREEN test itself — strictly test code,
+   never `src/`-side app code — and only BLOCK if test creation
+   fails. This is two changes: (a) tools — add `Write` (or `Edit`)
+   to the agent frontmatter, today `Read, Glob, Grep, Bash` only;
+   (b) discipline — Iron Law gains "you may write tests under
+   `crates/*/tests/` or `#[cfg(test)] mod tests`; you may NOT touch
+   any file outside test scope." The first real PASS run did not
+   exercise this path, so the constraint surfaces here as a future
+   tightening rather than as a tested behaviour.
+
 ## Known debt
 
 None.