Code Review — act101 Agent Skill

Code Review with act

Tools

Parser-only, always available:

• skeleton(file): structure, signatures, nesting depth.
• symbols(file): every symbol with kind and location.
• unsafe_surface(file): unsafe blocks, eval, raw SQL, FFI, reflective invocation, unsafe deserialization. Run it on any file handling input, queries, or native interop. modeled_kinds says which categories the grammar models; an empty surface with an empty mask is unmodeled, not clean.
• definition(symbol, file, line, column): where a symbol is defined, AST-based.

Language-server backed (the server starts on first call; status reports LSP readiness; references and callers name the answering server in resolved_by):

• diagnostics(files=[…]): compiler and linter errors, warnings, hints. Call it once over the change with every edited path in files, not once per file.
• references(symbol, file): every binding of a symbol; zero external references on an export means possibly dead.
• callers(symbol, file): call sites, for coupling and blast radius.
• get_type(file, line, column): inferred type at a position.

Explore broad to narrow: directory skeletons, then file symbols, then reference chains.

Workflow

Single file: diagnostics, then skeleton for function sizes and nesting, then symbols for density and naming.

Directory or module: skeleton per file for the structural overview; one diagnostics call over the files; references on exports to find unused public API; callers on key functions for coupling.

PR (changed files):

1. One diagnostics call over the changed files.
2. skeleton on changed files for the new structure.
3. references on renamed or moved symbols to confirm every binding moved.
4. callers on modified functions for direct impact, and analyze_impact(target=<file>, symbol=<name>) (Architecture) for transitive callers without LSP. Confirm the symbol name with skeleton first and read confidence, modeled_kinds, and unresolved.
5. analyze_api_diff(base_ref=<base>) (Architecture; CLI act analyze api-diff --base-ref <base>) when the PR touches public API. It diffs the merge-base of the base branch against the working tree and returns per-symbol rows and summary counts. Cite Breaking (a parameter added, an export removed), PossiblyBreaking (other signature drift), and Additive rows, and surface every Unjudgeable row: it names a grammar whose visibility act does not model, so that change is unjudged, not safe.
6. scan(root=<repo>, base_ref=<base>) for the AI-code security pass over the change: hardcoded credentials, .cursorrules backdoors, MCP-config RCE, typosquat or hallucinated dependencies, Actions expression injection, LLM-output-to-exec flows, prompt-injection surfaces, and the AI-Code Health Score. With base_ref the scan computes the changed set itself (merge-base, rename-aware) and discloses it in the report's scope section. Without a git base, pass files=[<changed files>] instead (scope.mode: "paths"). Either way the score covers only the selected files and is never comparable to a full-repo score. With a committed .act/baseline.json, add baseline=".act/baseline.json": baseline.new_finding_ids is then exactly the set of findings this change introduces.
7. gate(base_ref=<base>) (CLI act gate --base-ref <base>) for the merge-safety verdict over the whole changed set. Cite its output directly; the gate owns the rules, and verify_diff_semantics, verify_test_impact, and verify_side_effects are its inputs. Verdict semantics, exit codes, and degradation rules are in the safe-to-merge skill. UNKNOWN means not verified, never a pass.

gate --receipts (MCP gate(receipts=true)) writes per-function receipts to .act/receipts/. On a later run, functions matching a valid receipt report pre-verified by receipt <id>, which reviewers may accept without re-running the trio. Receipt mechanics are in the refactor-receipt skill. A behavior change with no test reaching it blocks:

$ act gate act gate — working tree vs HEAD (1 changed function(s)) BLOCK auth.ts::validateAge — behavior, NO test reaches it (behavior change with no test reaching it) verdict: BLOCK $ echo $? 1

What to look for

References

• review-patterns.md: review checklists and multi-file strategies.
• error-recovery.md: LSP failures, file not found, ambiguous symbols.

Output format

## Review: src/auth/login.ts

### Errors (2)
- Line 45: Type 'string' is not assignable to type 'number' [diagnostics]
- Line 72: Cannot find name 'authConfig' [diagnostics]

### Warnings (3)
- Line 15-80: Function `handleLogin` is 65 lines (>50 threshold) [skeleton]
- Line 23: Unused import 'lodash' [diagnostics]
- Line 90: `validateToken` has 0 external references — possibly dead code [references]

### Info (1)
- `processAuth` called from 12 locations — high coupling [callers]