fix(nightly): guards-nightly has been RED naming a step that runs every night

[noahgift]

Five scheduled lanes are red (guards-nightly, Coverage Nightly, Silicon Nightly,
examples-nightly, CUDA Nightly). This is the one whose cause is entirely inside the
guard rather than in the thing it guards.

FAIL: manifest names a step this workflow does not run:
      Test-tier decision case table (BSE-17): quick/full/reuse, drift is ENV

The step is there — guards-nightly.yml:158:

- name: "Test-tier decision case table (BSE-17): quick/full/reuse, drift is ENV"

The inline check matched the bare spelling:

grep -Fq -- "- name: $name" .github/workflows/guards-nightly.yml

A step name containing a colon-space must be quoted in YAML, and this one contains
(BSE-17): quick. So the matcher looked for - name: Test-tier… while the file said
- name: "Test-tier…, and the lane has been red since that name was quoted — reporting a step
that runs on every nightly as one the workflow does not run.

A guard that names a real step as missing is worse than no guard: it teaches the reader to skip
the lane.

Extracted, not patched in place

Logic inside a run: block cannot be unit-tested and cannot carry a case table — which is why
a one-character class of defect survived in it. scripts/check_guards_nightly_manifest.sh
matches on the parsed name, so all three YAML quotings of one string are one step.

bare name parsed                              ok
DOUBLE-quoted name unquoted (the defect)      ok
single-quoted name unquoted                   ok
trailing whitespace stripped                  ok
manifest fully covered            -> exit 0
a genuinely absent step           -> exit 1   <- still fails; not made permissive
vacuity floor, <5 entries parsed  -> exit 1

Against the real tree: ok 7 manifest entries, every one a step in this workflow. Mutation:
appending one bogus entry turns it red again, so the matcher was widened without being disarmed.

The self-test found a defect in its own harness first

Invoking step_names through bash -c 'source …' re-ran this file's own dispatch and returned
nothing, so four rows failed while the parser was correct. A broken harness reporting a
working parser as broken is the same error being fixed, in the other direction — worth
recording because the row that matters most is the one most easily faked, either way.

Also

check_roadmap_sorted.sh caught the roadmap entry at a stale slot: main gained PMAT-3228/3229
while this branch was being written, so "after 3222" was no longer sorted. Re-inserted among
its numeric peers.

guard_tree.sh --dry-run reports the new guard wired-elsewhere guards-nightly.yml;
check_guards_are_wired.sh exits 0. bashrs 7.4.1: 0 errors.

The other four red lanes are separate causes and are not touched here: Coverage Nightly
(llvm-cov), Silicon Nightly (the x86_64-cpu SIMD axis genuinely failing), examples-nightly
(an example failing), CUDA Nightly (PP-26 batch-invariance, a known divergence).

no-close: a CI lane fix with no filed issue; the four remaining red nightlies are separate
causes and need their own triage.

ont-delta: none — a CI guard fix; it adds no entity, shape, verdict reason or resolves target.

🤖 Generated with Claude Code

[github-actions]

§13.11 rung 1 — quorum shadow verdict

S13-SHADOW pr=3285 head=215c2865617b9d8c147923ac1f11f92e00aa1c83 verdict=REFUSE class=Q1 arm_rc=1

Shadow mode: this records a verdict and merges nothing. A refusal
to arm is not a block (§13 adds zero rows to §7) — the pull request is
exactly as green as it was.

[noahgift]

Superseded by #3295, which carries this change unmodified along with eight other
collision-free CI/guard PRs as a single merge-queue entry.

Not abandoned and not rejected: the commits are merged into
PMAT-3231-batch-1-ci-guards verbatim (clean=9 conflicted=0), and this branch is
retained — reopening is one click if #3295 does not land.

Why: a successful merge_group CI run is median 78 min with max_entries_to_merge = 1,
so nine entries is ~12 h of queue for 623 insertions. As one entry it is 78 minutes.
Root cause and the full five-whys: #3294.