Restore automatic pipeline agent selection

[harupong]

Summary

• select the no-mistakes pipeline agent dynamically from runnable tools instead of inheriting a fixed machine-global agent
• document the availability-routing boundary and the verified agent, authentication, and quota inventory
• assert the parsed YAML contract for agent: auto
• make test-runner coverage comparisons use the same deterministic C locale as their sorted inputs

Validation

• bin/fm-test-run.sh tests/fm-nm-test-contract.test.sh (Ruby 3.3.8 made available locally in the isolated copy): passed, including both YAML assertions
• bin/fm-test-run.sh tests/fm-test-run.test.sh: passed
• bin/fm-test-run.sh --check-coverage: passed
• bin/fm-lint.sh: passed with ShellCheck 0.11.0 and actionlint 1.7.12
• bin/fm-doc-audience-check.sh: passed
• /bin/bash -n bin/fm-test-run.sh tests/fm-test-run.test.sh: passed

[kunchenguid]

Speaking as Kun's firstmate: first look on fork PR #4427 (harupong).

Head bc6b782dc2bb0d6982149bbcf61ee7ae2f254d9d (fm/firstmate-quota-dynamic-selection-direct-pr-r1 from harupong) vs main b182d0f908b78d08c7ccb8dce3775bdca8c5d657. MERGEABLE / UNSTABLE. Author not blocked. Commits carry kunchenguid author email but the PR author is harupong (fork); body is not a Last-resort port of #N — triage as ordinary fork PR. First-time fork workflows were action_required; after diff review they were approved (CI run 34821727976, Require no-mistakes 34821727975). Tip CI still in progress at stamp; tip NM FAILURE (attestation missing).

Attestation: MISSING (no <!-- no-mistakes-pipeline-attestation:v1 marker in body). Tip Require no-mistakes 34821727975 FAILURE — “PR was not raised through no-mistakes”.

Contract-class: new-default (title “Restore” is not proof of restore). Evidence: tracked .no-mistakes.yaml gains always-on agent: auto for every consumer of this repository’s default-branch yaml. History of .no-mistakes.yaml on main never contained an agent: key (scanned prior path commits including #3865 / #3778 / #518 era) — so this is introducing a new unconfigured default path (availability routing), not restoring a prior promised setting. Locale LC_ALL=C around comm in bin/fm-test-run.sh / tests is a restorative locale-correctness fix, but it does not pull the PR below new-default while agent: auto lands as the tracked default. Docs claim “availability-based fallback, not quota-aware model ranking” — still a new default agent-resolution contract. Never auto-merge.

VISION.md per-rule

• One captain, one interface — aligns (pipeline agent choice stays below-deck; docs disclose inventory).
• Authority is explicit and never inferred — tension: tracked agent: auto changes gate-agent selection for the shared surface without a captain opt-in file; acceptable only as intentional distro default, which is exactly why this is new-default (captain card when otherwise ready), not auto-merge.
• Scripts own the mechanics, agents own the judgment — aligns (selection delegated to no-mistakes availability; locale comm stays script-exact).
• A restart is a non-event — neutral.
• Delegation with a spine — aligns (test asserts parsed agent: auto contract).
• The fleet outlives any vendor — aligns (availability across runnable tools; OpenCode ineligibility under disable_project_settings disclosed).
• Scope — aligns (validation/config/docs/tests only; no workshop expansion).

CI/NM: Fork CI approved and running (34821727976). Tip NM FAIL. Merge-eligible N. Waiting-author for a no-mistakes pipeline attestation that binds tip bc6b782d… (and green tip CI). Firstmate flag: no (not otherwise-ready; NM blocks before any captain new-default card).

Security: Diff review clean for fork approval — no credential files, no auth bypass, no .github/** workflow changes. docs/verification/dispatch-auth.md adds public inventory/probe documentation (quota TOON shapes, auth source labels) without embedding secrets. No security captain gate. Security tip N/A while waiting-author / attestation missing (FYI only if later tips).

Overlaps: No linked issue found for “automatic pipeline agent selection”. Not overlapping #1692 / watcher-burn surface.