(gauntlet): Gate once per round; run the title preflight with prefixes

[evanharmon1]

Problem

Two pieces of friction hit while running the gauntlet skill end to end on a real change (harmon-init PR #1043, 2026-08-23), both cheap to fix in the skill text:

1. The per-round gate runs the definition-of-done suite twice. The round recipe has the author run task verify (plus the secret scan) into the gate file, and the natural way to sequence "fix, verify, commit, push" ends up running task verify once to decide the commit and again to mint the gate marker for push-round.sh. On a repo whose verify takes minutes, that doubling pushed one round past a 10-minute command timeout. The skill should say plainly: run the gate suite once per round, into the gate file, and let that single run be both the done-check and the marker source — commit first, then gate, exactly once.

2. The release-title preflight is documented argless, which can be inert. The PR-open ritual shows PR_TITLE=… BASE_SHA=… task guard:release-title, but in repos where the Taskfile passes configured path prefixes (harmon-init runs require-release-title.sh template), invoking the script argless reports "no release-worthy path prefixes configured — nothing to guard" and exits 0. That false pass cost a failed guard check on the PR and a shepherd round. The skill should direct the preflight through the repo task (which carries the prefixes) and treat the "nothing to guard" message as "the guard is inert here", not as a pass.

Acceptance criteria

• [HUMAN] The gauntlet SKILL.md round recipe states the gate suite runs once per round (commit, then gate into the gate file, then push) and warns against a second pre-commit verify of the same tree.
• [HUMAN] The PR-open ritual's release-title step invokes the repo's own task (or the script with the repo's configured prefixes) and tells the reader that a "no prefixes configured" result means the guard did not evaluate the title.
• [CI] Skill lint/docs gates pass on the updated skill.

Verify

Read the shipped gauntlet SKILL.md sections for the round push and the PR-open ritual: the single-gate wording and the prefix-aware preflight wording are present; grep -n "nothing to guard" (or equivalent phrasing) appears in the preflight caveat.

Out of scope

Changing push-round.sh's marker protocol or the guard script itself; both behaved correctly.

Provenance

Found while doing evanharmon1/harmon-init#1043 — moved here because this repo owns the gauntlet skill.