LOC Guard

Use this skill whenever source files are created, edited, reviewed, or refactored.

The purpose of this skill is not to force tiny files. The purpose is to prevent oversized, hard-to-review, multi-responsibility files.

Thresholds

• 400 counted LOC is a review trigger, not an automatic refactor command.
• 600 counted LOC is a hard cap unless the user explicitly approves an exception.

Interpretation

When a changed or new file triggers the 400 LOC warning:

1. Inspect whether the file is still cohesive.
2. Check whether it has a clear single responsibility.
3. Decide whether the extra size is justified by necessary orchestration or simple linear structure.
4. Check whether the file is mixing separable responsibilities.
5. Consider likely near-term growth from upcoming slices before accepting the warning.
6. Split only when the split improves responsibility boundaries or reduces meaningful complexity.
7. Do not split purely to satisfy the number if the split adds indirection without design benefit.

Required behavior after editing

Run the LOC checker after source edits.

Preferred project-local command:

python3 .agent-tools/loc_guard.py . --config .agent-tools/loc-guard.config.json

If the project has not copied the checker into .agent-tools/, run the bundled checker from this skill instead:

python3 skills/loc-guard/scripts/loc_guard.py .

In Claude Code, when the skill is installed under ~/.claude/skills/ or .claude/skills/, use Claude's skill-directory variable for the bundled checker:

python3 "${CLAUDE_SKILL_DIR}/scripts/loc_guard.py" .

If no warning or failure occurs, no special report is needed.

If a file exceeds 400 counted LOC but stays at or below 600 counted LOC, report one of:

warning accepted with justification: ...

or:

split performed because: ...

If a file exceeds 600 counted LOC, do not continue as if the task is complete. Either:

1. split/refactor the file below the hard cap, or
2. ask the user for explicit approval for an exception.

Good warning justifications

Accepting a 400 LOC warning may be reasonable when:

• the file is cohesive and has one clear responsibility;
• most of the size is straightforward orchestration;
• splitting would create artificial indirection;
• the file is unlikely to grow much in the next slices;
• the file is a focused test suite with grouped cases;
• the change reduced complexity even if the file remains large.

Bad warning justifications

Do not accept a warning merely because:

• it was faster;
• refactoring was not requested;
• the file already existed;
• the agent wanted to avoid touching more files;
• the new code is "only temporary";
• the split would be slightly inconvenient.

Hard cap rule

A file over 600 counted LOC is a failed state for normal handwritten source files.

The user must explicitly approve any exception. Do not infer approval.

Generated, vendored, minified, designer, lock, snapshot, migration, and machine-produced files may be excluded by configuration.

Checker

The bundled checker is at:

scripts/loc_guard.py

Recommended project-local copy:

.agent-tools/loc_guard.py

Policy reference

For the full reusable policy text to copy into AGENTS.md, CLAUDE.md, or another agent instruction file, see:

references/loc-policy.md