fable-deep-review

fable-deep-review is a skill for Claude Code, Codex from rhein1/fable5-codex. It costs 54 tokens per session (741 once invoked), scanned A, original, MIT.

A deep code-review skill for pull requests, branches, diffs, commits, or proposed patches. It checks whether a change is correct and whether it may introduce regressions.

In plain words
What is it for?
Use it to review code before merging, investigate changes across a branch or commit range, find regressions, and produce review comments or verification results.
Why use it?
It provides an independent engineering review instead of merely summarizing the changes. It also defines different review approaches for large or high-risk work.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions subagents; mentions Codex.

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/rhein1/fable5-codex/fable-deep-review
Any agent
npx skills add rhein1/fable5-codex --skill fable-deep-review
Clone the repo
git clone --depth 1 https://github.com/rhein1/fable5-codex

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for fable-deep-review

README.md
[![agentmods](https://agentmods.dev/badge/skills/rhein1/fable5-codex/fable-deep-review.svg)](https://agentmods.dev/skills/rhein1/fable5-codex/fable-deep-review)
Your own site
<a href="https://agentmods.dev/skills/rhein1/fable5-codex/fable-deep-review"><img src="https://agentmods.dev/badge/skills/rhein1/fable5-codex/fable-deep-review.svg" alt="Measured on agentmods" height="20"></a>
Per session 54 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 741 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00054 $0.00741
Opus 5 $0.00027 $0.00370
Sonnet 5 $0.00011 $0.00148
Haiku 4.5 $0.00005 $0.00074

Measured 6d ago against content hash 2d3082127c1e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

fable-deep-review scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

plugins/fable5-codex/skills/fable-deep-review/SKILL.md · 54 lines

How it starts

The opening of the file, as written. The whole thing — 54 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Fable Deep Review

Review like a senior engineer validating a change, not like a summarizer. Default to no edits unless the user asks to address findings.

For ECF-style governed runs, use ../../references/ecf-run-contract.md. For large or high-risk reviews, use real Codex subagents when the runtime exposes a subagent tool and the user has not opted out; treat repo-wide, cross-package, security/privacy/money/data/API, migration, release, or deep-review requests as large by default. Otherwise run single-agent multi-lens and say why no subagents were used. For bot-parseable PR review output, use ../../templates/fable-review-contract.md.

For large or high-risk Fable tasks, recommend running the parent task on gpt-5.6-sol with Ultra (model_reasoning_effort = "ultra") when available. Ultra may delegate proactively, but still explicitly request parallel delegation for disjoint Fable lenses when the runtime supports subagents; otherwise use single-agent multi-lens and report the reason.

Workflow

  1. Identify the review target: PR, branch, diff, commit range, or files.
  2. Restate authority boundaries and declare the ECF run mode: multi-agent only with real spawned subagents, otherwise single-agent multi-lens.
  3. Read repo instructions and changed files completely before judging them.
  4. Inspect callers, importers, tests, docs, migrations, and generated/runtime surfaces touched by the change.
  5. Build a change map: intent, modified behavior, affected contracts, and risk areas.
  6. Generate candidate regressions from multiple lenses:
    • API/contract compatibility
    • data/schema and migration safety
    • concurrency/idempotency/retry behavior
    • auth, privacy, and permission checks
    • user-facing/runtime behavior
    • test adequacy and missing cases
  7. Verify each candidate. Prefer a small command or source trace that proves the issue.
  8. Report only actionable findings. Put open questions after findings.

Subagent Authority

Subagents may map changed files, inspect a review lens, draft candidate findings, or verify candidates. The main agent owns final severity, final findings, edits, commits, pushes, GitHub comments, and PR state changes. If a delegated review pass returns unsupported claims, report them as refuted or unknown rather than treating them as independent agreement.

Read the full file on GitHub · 54 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 6d ago First seen · 54 lines · 54 tokens per session scan A 2d3082127c1e

Subscribe to this mod's changes

fable-deep-review is a skill published in the GitHub repository rhein1/fable5-codex (4 stars, last pushed 16d ago), licensed MIT. It adds 54 tokens to every session and 741 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.