holocron/plugins/git/skills/pc-run/references/failure-patterns.md

source_keys

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context7-pre-commit-com pre-commit-com

Hook Failure Patterns

Common hook failure causes and concrete next-step suggestions.

Hook modified files — commit blocked

Cause: A fixer hook (e.g. trailing-whitespace, end-of-file-fixer, pretty-format-json) modified staged files. The commit is blocked because the staged version is now stale.

Fix: Re-stage and recommit.

git add -u
git commit -m "same message"

Do NOT reach for pre-commit install -f here. That flag overwrites existing hook files in .git/hooks/; it has nothing to do with re-staging.

Secret detected (gitleaks)

Not sourced from the pre-commit research corpus (context7-pre-commit-com/pre-commit-com cover pre-commit itself, not gitleaks) — general tool knowledge, verify against gitleaks' own docs if precision matters.

Cause: gitleaks found a high-entropy string or known secret pattern in a staged file.

Suggestions:

• If it's a false positive: add a # gitleaks:allow inline comment, or add the path to .gitleaksignore.
• If it's a real secret: remove it from the file, rotate the credential, then commit.

Shellcheck warning

Not sourced from the pre-commit research corpus — general tool knowledge, verify against shellcheck's own docs if precision matters.

Cause: shellcheck found a shell script issue. The output includes the file path, line number, and SC-code.

Fix: Look up the SC-code on shellcheck.net or pass --explain SCxxxx to shellcheck for a detailed explanation. The most common fixes:

• SC2086 (unquoted variable): wrap in double quotes.
• SC2046 (unquoted command substitution): wrap in double quotes.
• SC2181 (check exit code of $?): use if command; then directly.

check-hooks-apply fails

Cause: A hook's files/types filter matches zero files in the repo — the hook is dead weight.

Fix: Broaden the filter, or remove the hook if it no longer applies to this repo.

check-useless-excludes fails

Cause: An exclude pattern matches no files.

Fix: Remove or fix the pattern.

SSH cloning fails in CI

Cause: The CI environment lacks SSH credentials to clone hook repos over SSH.

Fix: Export SSH_AUTH_SOCK in the CI environment, or switch hook repo URLs to HTTPS.

HTTP proxy needed

Cause: The CI/sandbox network requires a proxy to reach hook repos.

Fix:

export http_proxy=http://proxy.example.com:3128
export https_proxy=http://proxy.example.com:3128
export no_proxy=localhost,127.0.0.1

rev is a branch name — autoupdate broke it

Cause: Branch refs are mutable and drift over time; pre-commit resolves them once at install time, so pinning to a branch name (instead of a tag or commit SHA) leads to silent version drift.

Fix:

pre-commit autoupdate     # finds the latest tag and rewrites rev in place

pretty-format-json fails but doesn't fix

Cause: pretty-format-json requires args: [--autofix] to modify files. Without it, the hook only fails.

Fix: The user (or pc-author) must add args: [--autofix] to the hook override in .pre-commit-config.yaml.

Environment stale or broken

Cause: A hook's cached environment is corrupted or out of date.

Fix: pre-commit clean is gated. It wipes the machine-wide cache at ~/.cache/pre-commit, shared by every repo on the box, so get explicit confirmation before running it — "This will wipe the entire pre-commit cache. All hook environments will be re-downloaded on next run. Proceed?"

pre-commit clean          # gated — confirm with the user first
pre-commit install-hooks  # rebuild everything

Or less destructively, needing no confirmation:

pre-commit gc             # remove only unused environments

Hooks don't run on git commit

Cause: pre-commit install was never run in this clone.

Fix: pre-commit install. Git hooks are per-clone — they are not committed to the repo.

Hook runs but matches wrong files (or no files)

Cause: The files: pattern uses re.search() not full-string match. A pattern that looks correct may match unexpectedly.

Diagnosis: identify-cli <filename> shows the type tags for a file. Verify types: filters against these.

stages mismatch — hook never fires

Cause: Hook is defined for a stage (e.g. pre-push) but pre-commit install was not run with -t pre-push.

Fix:

pre-commit install -t pre-commit -t pre-push -t commit-msg

Or add default_install_hook_types to .pre-commit-config.yaml and re-run pre-commit install.

validate-config schema error

Common causes:

• Missing id under a hook block
• Missing rev under a non-local repo block
• repo: local hook missing language or entry
• Indentation error (valid YAML but invalid pre-commit schema)