[dnth]

Summary

Ports upstream 833a9a25 (kunchenguid#1925) behavior: bin/fm-lint.sh now picks its file set from git context instead of always sweeping the full canonical set, so a local branch and the No-Mistakes gate stop repeating the full ShellCheck run that CI already owns.

 fm-lint.sh (no explicit paths)
-  full canonical set + --external-sources, on every branch
+  CI (GITHUB_ACTIONS/CI) | main | no merge-base
+    full canonical set + --external-sources
+  local branch with a merge-base
+    changed canonical files only, including tracked uncommitted edits
+    no --external-sources; exclude SC1091,SC2034,SC2153,SC2329
+  local branch with zero changed targets
+    "no changed lint targets" + exit 0, before any dependency check
   explicit paths and --list-files keep their full posture

Changed files:

• bin/fm-lint.sh - context selection, conditional worker flags, zero-target return.
• tests/fm-lint.test.sh - fixture-repo cases for changed mode, CI/main/no-merge-base full mode, zero targets without lint dependencies, explicit-path bypass, and exclusion behavior.
• .no-mistakes.yaml, CONTRIBUTING.md, docs/configuration.md, .github/workflows/ci.yml - invoke the default context-selected mode and point at the header as the owner of the split.

Evidence

• Before: every local run and the No-Mistakes lint step swept the full canonical set - 444 roots, about 270k lines; the No-Mistakes lint step took 1,630,548 ms (run 01M796S134JFXVZXT5JVHEMWAY).
  After: on this branch the local lint selects 2 changed canonical roots, and exits 0 in about 1 s with local changed-file mode; source following disabled, excluding SC1091,SC2034,SC2153,SC2329.

• Before: no case proved zero changed targets exit cleanly when ShellCheck or Perl is absent, or when the ShellCheck version differs.
  After: test_zero_changed_files_prints_the_note_and_exits_zero proves all three dependency scenarios print no changed lint targets and exit 0, while the version-rejection test proves a wrong version still fails with a target present.

• bash tests/fm-lint.test.sh - 19/19 ok, including changed-mode selection, full-mode parity for CI/GITHUB_ACTIONS/main/no merge-base, zero targets, explicit-path bypass, and real-ShellCheck exclusion behavior.

• env -u CI -u GITHUB_ACTIONS bin/fm-lint.sh - changed mode, 2 roots, exit 0.
  bin/fm-lint.sh bin/fm-lint.sh tests/fm-lint.test.sh - full source-aware posture on the changed roots, exit 0.

• gh-axi pr checks 304 - 20/20 checks pass, including Lint shell scripts; CI owns the full canonical sweep.

• Source: upstream 833a9a25 (feat(bin): lint only the changed shard locally, full lint in CI kunchenguid/firstmate#1925, "lint only the changed shard locally, full lint in CI"), with the no---external-sources posture from follow-up a29cdcef (fix: reduce local ShellCheck source-analysis cost kunchenguid/firstmate#3778). Upstream partitions, --fast, and memory-bound machinery are not ported.

Merge Danger

Door: two-way - reverting restores the single full-sweep path; there is no data, schema, or state migration.

Blast Radius: firstmate lint gates only.

Local changed-file runs and the No-Mistakes lint step no longer report the four cross-file codes; CI still runs them over the full canonical set, so coverage is deferred, not dropped. --list-files stays the full inventory, so documented syntax sweeps do not narrow.

Pipeline

Updates from git push no-mistakes

✅ **Intent** - passed

✅ No issues found.

✅ **Rebase** - passed

✅ No issues found.

🔧 **Review** - 1 issue found → auto-fixed (2) ✅

• 🚨 bin/fm-lint.sh:264 - AC3 requires: “A branch with no changed canonical files prints a ‘no changed lint targets’ note and exits 0.” The new zero-target exit occurs after dependency checks, so a docs-only branch without ShellCheck exits 127, with another ShellCheck version exits 1, or without Perl exits 127, without printing the required note. The conflicting guards are bin/fm-lint.sh:241 (ShellCheck availability), :248 (Perl availability), and :254 (version). Move the zero-target return before these checks while retaining them whenever targets exist. The zero-target test at tests/fm-lint.test.sh:245 currently supplies all dependencies and misses these cases.

🔧 Fix applied.
2 issues (1 error, 1 warning) still open:

• 🚨 bin/fm-lint.sh:264 - AC3 requires: “A branch with no changed canonical files prints a ‘no changed lint targets’ note and exits 0.” The new zero-target exit occurs after dependency checks, so a docs-only branch without ShellCheck exits 127, with another ShellCheck version exits 1, or without Perl exits 127, without printing the required note. The conflicting guards are bin/fm-lint.sh:241 (ShellCheck availability), :248 (Perl availability), and :254 (version). Move the zero-target return before these checks while retaining them whenever targets exist. The zero-target test at tests/fm-lint.test.sh:245 currently supplies all dependencies and misses these cases.
• ⚠️ bin/fm-lint.sh:241 - Round 1 correctly moved the empty-target exit before dependency checks, but left a sibling test assumption behind at tests/fm-lint.test.sh:487–490. On a docs-only local branch with a merge-base, running tests/fm-lint.test.sh now fails: its version-rejection test invokes lint without targets, receives the required successful empty-target result, and labels that a version-check failure. Give that test an explicit fixture path so version rejection is checked whenever lint targets exist; retain the empty-target behavior at bin/fm-lint.sh:241–243.

🔧 Fix applied.
✅ Re-checked - no issues remain.

✅ **Test** - passed

✅ No issues found.

• Live validation: ✅ go - 5 of 5 scenarios driven live against the product

Scenario	Result	Live	Evidence
Local synthetic branches analyze only committed, staged, and unstaged canonical changes using either base reference	✅ pass	live	cli-transcript.log: local-origin and local-main-fallback
CI flags, main, and unrelated history retain full canonical source-aware analysis	✅ pass	live	cli-transcript.log: full-CI, full-GITHUB_ACTIONS, full-main, full-no-merge-base
A docs-only branch prints the empty-target note and succeeds despite unavailable lint dependencies	✅ pass	live	cli-transcript.log: empty-no-dependencies and empty-wrong-version-no-perl
Explicit paths bypass selection and retain full diagnostics while local mode suppresses cross-file findings	✅ pass	live	cli-transcript.log: explicit-unchanged, explicit-missing-perl, cross-file-local, cross-file-explicit
Inventory queries return the complete canonical set independently of selection mode	✅ pass	live	cli-transcript.log: inventory-local, inventory-CI, inventory-GITHUB_ACTIONS

• TMPDIR="$PWD/.local-lint-validation/tmp" bash tests/fm-lint.test.sh — exited 0.
• python3 .local-lint-validation/drive.py — exercised real CLI selection and fallback behavior with real ShellCheck 0.11.0.
• Executed staged cross-file fixtures through default and explicit-path modes; verified actual diagnostic differences.
• Removed disposable fixtures, confirmed clean Git status, and awaited every launched process.

✅ **Document** - passed

✅ No issues found.

✅ **Lint** - passed

✅ No issues found.

✅ **Push** - passed

✅ No issues found.