kelp/plugins/tiger-style/skills/tiger-check

/tiger-check [file]

Audit Zig source files for mechanical Tiger Style violations. If a file path is given, check that file. Otherwise check all *.zig files that were modified in the current git diff (staged and unstaged).

Only mechanical, statically-detectable rules are covered. Subjective rules (naming quality, prose, "simplicity") are not. For those, lean on the patterns in ${CLAUDE_PLUGIN_ROOT}/docs/TIGER_STYLE_REFERENCE.md.

Procedure

1. Determine target files

If argument provided:

• Check only that file.

If no argument:

• Run git diff --name-only and git diff --cached --name-only.
• Filter to *.zig files (include any path, not just src/*.zig).
• If no modified Zig files, report "No modified Zig files to check" and exit.

2. Read each target file

Use the Read tool to read the full contents.

3. Check for violations

Apply each check below to each file. Report every violation with file path, line number (or line range for function-length), and a one-line fix suggestion.

Check 1: Function length > 70 lines

For each function definition (fn name(...) or pub fn name(...)), measure from the opening { line through the matching closing }. If the body spans more than 70 lines (closing line minus opening line

70), flag it.

Report: WARN: <start>-<end>: function '<name>' is <N> lines (limit 70).

Fix: "Split into helper functions. Push fors down into helpers; keep branching in the parent."

Check 2: Line length > 100 columns

For each line whose character length exceeds 100, flag it.

Caveats:

• Skip lines that are entirely a single string literal (e.g. a long URL in a comment or const), since wrapping would change semantics. Flag with a note rather than as a violation.

Report: WARN: <line>: line is <N> columns (limit 100).

Fix: "Wrap with zig fmt (add trailing comma to the preceding signature/call) or extract the long expression into a named const."

Check 3: usize usage

Grep each file for the token usize. For each occurrence, flag it.

Caveats:

• usize is required when interfacing with stdlib APIs that return it (.len, allocator sizes, etc.). The rule is "avoid where you control the type," not "ban outright." Include a note encouraging the user to verify whether the use site is constrained by an external API.

Report: WARN: <line>: 'usize' used; prefer explicitly- sized type (u32, u64) unless required by stdlib API.

Fix: "Use u32 or u64 if you control the type; keep usize only when bound by an external API signature."

Check 4: Direct recursion

For each function definition, scan its body for calls to the function's own name. Flag any match.

Caveats:

• inline fn recursion bounded at comptime is sometimes acceptable; flag with a note rather than bare violation when the function is inline fn.
• Mutual recursion (A calls B, B calls A) is not caught by this check; document the limitation in the report footer.

Report: WARN: <line>: function '<name>' recurses directly; Tiger Style requires iteration with an explicit stack.

Fix: "Convert to iteration with a bounded stack (std.ArrayListUnmanaged of frames, sized at init)."

Check 5: Compound assertions

Grep for assert( calls whose argument contains a top-level and or or (outside nested parentheses or string literals). Flag each.

Report: WARN: <line>: compound assertion -- split into separate asserts for clearer failure messages.

Fix: "Replace assert(a and b); with assert(a); and assert(b); on separate lines."

Check 6: Bare while (true) without adjacent assert

For each while (true) (and equivalent like while (true) : ()), read the loop body. If the body does not contain at least one assert( call within the loop's direct scope (not inside a deeply nested function), flag it.

Report: WARN: <line>: 'while (true)' without an assertion in the loop body; non-terminating loops must assert their invariant.

Fix: "Add assert(<invariant>); near the top of the loop body to document why the loop is allowed to never terminate."

4. Report results

Format output as:

## /tiger-check Results

### <file_path>

WARN: <line>: <description>
  Fix: <suggestion>
WARN: <line>: <description>
  Fix: <suggestion>

### <file_path>

No violations found.

---
Summary: X warnings across Z files

If no violations across all files:

## /tiger-check Results

All files pass. No Tiger Style violations found.

5. Caveats footer

Always append:

---
Note: /tiger-check covers mechanical rules only. It
does not check naming quality, comment prose, scope
minimization, mutual recursion, or dynamic allocator
usage after init. Review against
`${CLAUDE_PLUGIN_ROOT}/docs/TIGER_STYLE_REFERENCE.md`
for those.