drill 0.6.0: probes 1, 3 and 4 recorded from their runs

drills/0.6.0.md

@@ -81,13 +81,86 @@ One row per probe, written from its run. Runs are in
 
 | # | probe | run | result |
 |---|---|---|---|
-| 1 | merge-door ceremony | — | — |
+| 1 | merge-door ceremony | 30992108742 (attempt 1) | ✅ exactly one `0.6.0` release; tag equals the merge commit; main re-armed to `0.6.1-dev` |
 | 2 | mislabeled ordinary PR | 30991634654 | ✅ green NOTICE no-op; no tag, no release |
-| 3 | bare-version PR without `release` | — | — |
-| 4 | re-run completed ceremony | — | — |
+| 3 | bare-version PR without `release` | 30991832001 | ✅ refused at decide; no tag, no release |
+| 4 | re-run completed ceremony | 30992108742 (attempt 2) | ✅ refused at the nothing-exists assert; the release count stayed one |
 | 5 | manual matching tag | — | — |
 | 6 | mismatched tag | — | — |
 
+### Probe 1 — the merge-door ceremony
+
+PR #4 (`probe1-ceremony`) bumped `0.6.0-dev` to bare `0.6.0` and stamped
+`## 0.6.0 — 2026-08-05`, assembled from the three fixture fragments by the
+candidate's own `bin/changelog-assemble` and committed with the deletions
+in one commit. The `release` label was applied and confirmed before the
+merge. Facts and verdict:
+
+```text
+  VER: 0.6.0
+  BASE_VER: 0.6.0-dev
+  RELEASED:
+  LABELED: yes
+ceremony=yes
+```
+
+Observed after the run:
+
+- **Exactly one** release: `GET /releases` returned `0.6.0` alone, not a
+  draft, not a pre-release, zero assets (no artifact hook in the fixture —
+  the hook step skipped).
+- `GET /tags` returned `0.6.0` alone, pointing at
+  `64d02539f4a20286afc08b9997f0f8a7d1dbfccd`, which is PR #4's merge commit
+  — the tag names the tree that was reviewed.
+- The release body was byte-for-byte the assembled section's bullets:
+
+  ```text
+  - A second ordinary fragment, written by probe 2 of the 0.6.0 drill (#249).
+  - An ordinary behavior change, landing under the release label (#249).
+  - Fragment mode is exercised by the ceremony 0.6.0 drill (#249).
+  ```
+
+- Main re-armed itself: commit `2d0e19a` ("bump main to 0.6.1-dev — a dev
+  install must not impersonate 0.6.0"), pushed by the job's own token. Main
+  reads `0.6.1-dev` and `changelog.d/` holds only `README.md`.
+- **The anti-recursion property held.** Neither the tag create nor the bump
+  push started a workflow run — the run list after the ceremony ends at
+  30992108742. That is what makes the merge door the release's only chance
+  to publish, and it is the reason probe 4 below is the door's own guard
+  rather than a second run's.
+
+### Probe 4 — a re-run of the completed ceremony
+
+Re-running 30992108742 as attempt 2 re-decided `ceremony=yes` — the facts
+at that merge commit have not changed — and then died at the assert:
+
+```text
+tag '0.6.0' already exists — this release already happened, or a manual tag won the race; refusing to re-release, creating nothing.
+```
+
+Tag, publish and bump all skipped. `GET /releases` still returned exactly
+one `0.6.0`. The refusal is loud (the job is red) and creates nothing, which
+is the required shape: the assert is what covers a manual tag racing the
+merge, not only an operator's stray re-run.
+
+### Probe 3 — a bare-version PR without the `release` label
+
+PR #3 (`probe3-bare`) bumped `VERSION` to bare `0.6.0` and carried no label;
+the label list was read as empty before merging. The merge run refused at
+decide, row 5 of the table:
+
+```text
+  VER: 0.6.0
+  BASE_VER: 0.6.0-dev
+  RELEASED:
+  LABELED: no
+the version transitioned ('0.6.0-dev' -> '0.6.0') but no merged, release-labeled PR is behind this commit — a release is a labeled ceremony PR, not a bare push — creating nothing.
+```
+
+Notes, the assert, tag, hook, publish and bump all skipped; tags and
+releases were both still empty afterwards. The merge was then undone and
+main re-armed to `0.6.0-dev` before the ceremony probe ran (see Setup).
+
 ### Probe 2 — a mislabeled ordinary PR
 
 PR #2 (`probe2b-mislabeled`) added one changelog fragment and touched no