PostToolUse hook that flags two review hazards as Claude writes files: edits to generated or vendored artifacts (lockfiles, minified bundles, source maps, dist/build output, snapshots, protobuf output) and oversized diffs that change more lines than a configurable threshold versus the committed version.
Open the source and read safety notes before installing.
Source-backed facts for citing this resource, derived directly from the registry — also available as plain text for AI assistants.
Decision playbook
Signals are present but mixed. Use the checklist below to confirm the source and operational safety for your environment.
0
78
—
No baseline selected
No major trust-signal divergence detected in the current selection.
Confirm ownership and provenance before trusting install instructions.
Source link availableRequired
Open the canonical repository and verify ownership.
Source provenance statusRequired
Marked as source-backed.
Metadata reviewed
Registry metadata indicates a reviewed listing.
Validate risk disclosures before installation or API wiring.
Safety notes presentRequired
Review the listed safety guidance before running commands.
Privacy notes presentRequired
Review data handling notes before connecting accounts or secrets.
Trust level risk gateRequired
Trust level does not block evaluation.
Check package metadata and artifact integrity signals.
Install payload available
Install or copy payload is available for review.
Package verification flag
No package verification flag provided.
Checksum metadata
No checksum provided for downloaded artifact.
Use compare context to validate trade-offs before adoption.
Compare tray has multiple entries
Add at least one more entry to compare trust differences.
Baseline comparison available
No baseline peer selected yet.
Diverging trust signals identified
No major trust-signal divergence found.
Setup at a glance
Copy-ready — paste the snippet to get started.
Adoption plan
Current risk score 16/100. Use staged verification before broader rollout.
Validate source and review signals before any execution.
Confirm source provenanceRequired
Source URL/provenance metadata is present.
Confirm metadata review state
Listing has review metadata.
Verify install payload
Install/config payload exists and can be inspected.
Confirm safety, privacy, and package integrity signals.
Review safety notesRequired
Safety notes are present.
Review privacy notesRequired
Privacy notes are present.
Verify package integrity metadata
No package verification/checksum metadata.
Adopt in controlled steps based on the selected plan.
Run in isolated sandbox firstRequired
Use a constrained sandbox and observe behavior across multiple tasks.
Roll out graduallyRequired
Roll out to a small cohort before wider usage.
Set monitoring and fallback
Define rollback path and monitor errors after adoption.
Evidence readiness
Required evidence gates are covered (5/6 signals complete).
Source repository/provenance is listed.
Required in this preset
Review metadata is present.
Required in this preset
Safety notes are present.
Required in this preset
Privacy notes are present.
Optional in this preset
Package integrity metadata is missing.
Optional in this preset
Install payload is available.
Required in this preset
Required evidence gates are covered for this preset.
Decision timeline
5/6 steps complete with no blocking gaps for this preset.
triage
Source/provenance metadata is available.
triage
Review metadata is available.
verify
Safety notes are available.
verify
Privacy notes are available.
verify
Package integrity metadata is missing.
rollout
Install payload is available.
No required blockers for this timeline preset.
Prerequisite readiness
3 prerequisites to line up before setup.
Safety & privacy surface
4 safety and 3 privacy notes across 3 risk areas. Review closely: network access.
#!/usr/bin/env bash
set -u
# Claude Code PostToolUse hook. Flags two review hazards after a write/edit:
# (1) the target is a generated or vendored artifact, and (2) the diff versus
# the committed version exceeds a line threshold. Advisory only - it always
# exits 0 and never blocks - and fails open if jq is unavailable.
command -v jq >/dev/null 2>&1 || exit 0
INPUT=$(cat)
FILE=$(printf '%s' "$INPUT" | jq -r '.tool_input.file_path // .tool_input.path // ""')
[ -z "$FILE" ] && exit 0
LINE_THRESHOLD=${GENERATED_DIFF_LINE_THRESHOLD:-500}
# 1) Generated / vendored artifact paths that are usually regenerated, not
# hand-edited (mirrors common linguist-generated / linguist-vendored sets).
case "$FILE" in
*package-lock.json|*pnpm-lock.yaml|*yarn.lock|*.min.js|*.min.css|*.map|*/dist/*|*/build/*|*/out/*|*/vendor/*|*.snap|*/__snapshots__/*|*.generated.*|*_pb2.py|*.pb.go)
echo "Generated artifact - $FILE looks generated or vendored; prefer regenerating it or marking it linguist-generated in .gitattributes instead of hand-editing." >&2
;;
esac
# 2) Oversized diff against the committed version (only when git-tracked).
if command -v git >/dev/null 2>&1 && git rev-parse --is-inside-work-tree >/dev/null 2>&1; then
changed=$(git diff --numstat HEAD -- "$FILE" 2>/dev/null | awk '{sum += $1 + $2} END {print sum + 0}')
case "$changed" in
''|*[!0-9]*) changed=0 ;;
esac
if [ "$changed" -ge "$LINE_THRESHOLD" ]; then
echo "Large diff - $FILE changes $changed lines vs HEAD (threshold $LINE_THRESHOLD); consider splitting into smaller, reviewable commits." >&2
fi
fi
exit 0{
"hooks": {
"PostToolUse": [
{
"matcher": "Write|Edit|MultiEdit",
"hooks": [
{
"type": "command",
"command": "$CLAUDE_PROJECT_DIR/.claude/hooks/large-generated-diff-detector.sh"
}
]
}
]
}
}dist//build//out//vendor/ trees, snapshots, and protobuf output.HEAD and warns past a configurable threshold (GENERATED_DIFF_LINE_THRESHOLD, default 500).0, so it surfaces churn without blocking the edit.On PostToolUse, the hook reads the edited file path from the tool input. It matches that path against a set of generated/vendored patterns and, when inside a git work tree, runs git diff --numstat HEAD -- <file> to total the changed lines. Either signal prints an advisory message to stderr; neither blocks the write.
package-lock.json or minified bundle from being hand-edited or buried in a review.linguist-generated so diffs collapse in review.mkdir -p .claude/hookstouch .claude/hooks/large-generated-diff-detector.shchmod +x .claude/hooks/large-generated-diff-detector.sh.claude/settings.json (project) or ~/.claude/settings.json (user).{
"hooks": {
"PostToolUse": [
{
"matcher": "Write|Edit|MultiEdit",
"hooks": [
{
"type": "command",
"command": "$CLAUDE_PROJECT_DIR/.claude/hooks/large-generated-diff-detector.sh"
}
]
}
]
}
}
GENERATED_DIFF_LINE_THRESHOLD — changed-line count (added + removed) above which a diff is flagged. Defaults to 500.case patterns for your stack (for example Go *.pb.go, Python *_pb2.py, or framework-specific build dirs).Show that Large Generated Diff Detector - Claude Code Hook is listed on HeyClaude. Paste this Markdown into your README — it renders the badge and links back to this page.
[](https://heyclau.de/entry/hooks/large-generated-diff-detector)Large Generated Diff Detector - Claude Code Hook side by side with 3 alternatives on trust, install, platform support, and disclosed safety notes — all from reviewed registry metadata.
2 trust signals differ across this comparison (Source provenance, Submitter).
| Field | PostToolUse hook that flags two review hazards as Claude writes files: edits to generated or vendored artifacts (lockfiles, minified bundles, source maps, dist/build output, snapshots, protobuf output) and oversized diffs that change more lines than a configurable threshold versus the committed version. Open dossier | PostToolUse hook that flags risky package-lock.json, yarn.lock, and pnpm-lock.yaml edits: missing lockfile updates, unexpected registry hosts, and dependency count spikes before merge. Open dossier | PostToolUse hook that compares a just-edited OpenAPI or JSON Schema document against the version committed in git and warns about backward-incompatible drift — removed OpenAPI paths and removed required properties — so breaking API changes are surfaced before they ship. Advisory only; it never blocks the edit. Open dossier | Detects unused CSS selectors when stylesheets are modified to keep CSS lean using PurgeCSS, PostCSS, and content analysis. This hook runs on CSS/SCSS file write/edit operations and analyzes stylesheets to identify unused selectors, generate optimized output, and report before/after size metrics. Open dossier |
|---|---|---|---|---|
| Next steps | ||||
| Trust | ||||
| Review status | ReviewedMaintainer reviewed | ReviewedMaintainer reviewed | ReviewedMaintainer reviewed | ReviewedMaintainer reviewed |
| Package trust | Package not verified | Package not verified | Package not verified | Package not verified |
| Source provenanceDiffers | Source-backed | Submission linkedSource submission | Source-backed | Source-backed |
| SubmitterDiffers | jony376 | kiannidev | jony376 | — |
| Install risk | Review first | Review first | Review first | Review first |
| Notes | Safety ✓ Privacy ✓ | Safety ✓ Privacy ✓ | Safety ✓ Privacy ✓ | Safety ✓ Privacy ✓ |
| Brand | — | — | — | — |
| Category | hooks | hooks | hooks | hooks |
| Source | Source-backed | Source-backed | Source-backed | Source-backed |
| Author | jony376 | kiannidev | jony376 | JSONbored |
| Added | 2026-06-04 | 2026-06-17 | 2026-06-04 | 2025-09-19 |
| Platforms | ||||
| Harness | ||||
| Source repo | — | — | — | — |
| Safety notes | ✓Runs after every Write, Edit, and MultiEdit and inspects only the edited file path and its line-change count. Stays read-only and uses git diff --numstat to count changed lines; it never edits, stages, or commits anything. Advisory by design and always exits 0, so it never blocks a write even when it flags a large or generated diff. The line threshold defaults to 500 and is configurable through the GENERATED_DIFF_LINE_THRESHOLD environment variable. | ✓Read-only advisory hook; it does not block writes unless you wrap it with strict exit handling. Does not substitute for npm audit, OSV scans, or CI dependency review. | ✓Runs after every Write, Edit, and MultiEdit and only inspects JSON files that declare openapi, swagger, a $schema key, or paths. Stays read-only and runs git show to read the committed version; it never edits, stages, or commits anything. Advisory by design and always exits 0, so it never blocks a write even when drift is detected. Uses key-set comparison heuristics for removed paths and required fields, so it catches common breaking changes but is not a full OpenAPI diff. | ✓Runs automatically on its configured Claude Code hook event and executes shell logic that can read, modify, or delete files in your project (and may run builds, installs, or network calls); review the script and scope it to expected paths before enabling. |
| Privacy notes | ✓Reads only the edited file path from the tool input and the git numstat for that path; it does not read or transmit file contents. Prints the file path and a changed-line count to local hook stderr; it makes no network calls and writes no logs. The file path shown in output may reveal local directory structure in your terminal. | ✓Lockfile paths and registry hostnames are printed locally to stderr for the active session. | ✓Reads the edited schema file and its committed HEAD version from the local repository only. Prints removed path and required-field names to local hook stderr; it makes no network calls and writes no logs. Path and field names shown in output may reveal internal API surface in your terminal. | ✓Receives Claude Code hook input (session metadata, file paths, and tool output) and reads local project files; review what the script logs or forwards to external services and keep credentials out of its output. |
| Prerequisites |
|
|
| — none listed |
| Install | | | | |
| Config | | | | |
| Citations | ||||
| Claim | Unclaimed | Unclaimed | Unclaimed | Unclaimed |
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