### Added

- `docs/RUNNER-PROBES.md` documents the standing runner-probe venue,
  `heavy-duty/ceremony-runner-probe` — the place runner-only facts are measured
  on demand, ruled as option A by the operator (#202).

- `drills/README.md` cross-links it beside the disposal rule, so the exception
  is visible where the dangerous habit lives (#202).

- The runbook states that the drill disposal rule does **not** apply to it.
  Archiving it defeats its purpose, and that is exactly how the three existing
  drill repos each became unavailable (#202).

- It records that a probe must run as an Actions job under the workflow token:
  the same call answers 500 there and 204 under a PAT, so a probe run any other
  way produces a confident wrong answer (#202).

- Creating the repo is recorded as the operator's step, measured rather than
  assumed: a fleet identity gets 403 on org repo creation and 201 in its own
  namespace (#202).

- It carries an executable two-layer arming procedure: an immutable candidate
  code SHA and an armed workflow commit on top of it. A single layer is
  self-referential — rewriting a workflow makes a new commit, and a commit
  cannot contain its own object ID (#202).

- Callers are pinned by layer: composite actions to the candidate code SHA,
  reusable workflows to the armed SHA, which is the only revision whose inner
  checkout points at the fork (#202).

- The arming gate asserts what each carrier IS, not only that the old literal
  is gone: every `repository:` equals the fork, both `CEREMONY_SELF_REF` values
  equal the candidate code SHA, and callers match the layer they belong to
  (#202).

- It enumerates the carriers from the tree rather than encoding a count, and
  distinguishes ceremony's internal self-checkouts from the consumer checkouts
  that must stay `${{ github.repository }}` (#202).

- The published snippet parses, lints clean and runs: driven against an unarmed
  tree it refuses, naming the carrier (#202).

- Probe results are written to an issue in the probe repo and carried to the
  ceremony issue by a human, so the probe holds no path that can write to the
  live board (#202).