---
name: fable-5-code-review
description: "Deep multi-file code review powered by Fable 5's long-context reasoning — whole-PR understanding. Leverages Fable 5's 1M-token context and deeper reasoning for whole-repository code review: cross-file invariant checking, architectural drift detection, security analysis that follows data flow across modules, and review summaries that explain WHY a change is risky, not just where."
license: MIT
---

# Fable 5 Code Review

Fable 5 Code Review brings whole-PR understanding to your review workflow by loading the entire changeset — plus the surrounding files it touches — into Fable 5's 1M-token context window. Instead of flagging line-level nits in isolation, it reasons across modules: tracing how a renamed function ripples through callers, whether a new code path violates an invariant established three files away, and where a refactor has quietly drifted from the codebase's existing architecture. It's built for engineers reviewing large or cross-cutting PRs where the hard bugs live in the seams between files.

## When to use it

- Reviewing a PR that spans many files or touches shared interfaces, schemas, or state machines.
- Auditing changes to authentication, authorization, input handling, or anything where a vulnerability follows data across function and module boundaries.
- Catching architectural drift — a feature that bypasses the repository layer, a direct DB call in a controller, an abstraction leak.
- Onboarding to an unfamiliar codebase where you need the *why* behind a change, not just a list of diffs.

## How it works

The skill collects the diff (via `git diff` against your base branch) and resolves the dependency neighborhood of every changed symbol, then submits the assembled context to Fable 5 for a single coherent reasoning pass. Output is grouped by concern — correctness, security, architecture — and each finding cites the specific files and lines involved along with an explanation of the failure mode and blast radius.

```bash
curl -fsSL --create-dirs -o ~/.claude/skills/fable-5-code-review/SKILL.md https://claudeskil.com/skills/fable-5-code-review/SKILL.md

# Review the current branch against main
claude review --skill fable-5-code-review --base main

# Focus on security data-flow analysis, post inline on the PR
claude review --skill fable-5-code-review --focus security --comment
```

You can scope a review with `--base <ref>` and narrow attention with `--focus correctness|security|architecture`. Add `--comment` to publish findings as inline PR comments.

## Tips & gotchas

- Large context is a budget, not free lunch. If a diff plus its neighborhood exceeds ~1M tokens, the skill prioritizes changed files and their direct dependents — pull vendored or generated directories out of scope with a `.reviewignore` to keep signal high.
- Run it against a meaningful `--base`. Reviewing against `HEAD~1` only sees the last commit; use the actual branch point for whole-PR reasoning.
- Architecture findings reflect patterns it infers from your repo. If you have explicit conventions, reference a CONTRIBUTING or ADR file so drift detection anchors to your intent rather than the statistical majority.

## FAQ

**Does it modify my code?** No. Review is read-only and emits findings. Use a separate fix workflow if you want patches applied.

**Will it replace my linter or test suite?** No — it complements them. It targets semantic and cross-file issues that static linters and unit tests structurally cannot see, like invariant violations spanning modules.

**Can it review private repos without sending the whole repo?** It sends only the diff and the dependency neighborhood of changed code, not the entire repository, and respects `.reviewignore` exclusions.