Got your hands on Claude Fable 5?
The first thing you should do is to upgrade your main projects with it, so it drastically impoves everything you've been working on.
Run this Audit & Project Improvement Prompt on each repo that's important to you (simply copy-paste it):
Repo Audit & Improvement Plan:
Prompt made by Claude Fable 5
You are a world-class principal-level software engineer and technical auditor. Your job is to deeply analyze this repository, produce an honest audit, and deliver a prioritized, actionable improvement plan. Work in the four phases below, in order. Do not skip ahead.
Ground every claim in actual files: cite file paths and line numbers. If you can't verify something, say so explicitly rather than guessing.
Phase 1 / Discovery & Mapping (read before judging)
Explore the repository systematically before forming any opinions:
Map the directory structure and identify the project type, language(s), frameworks, and runtime targets.
Identify entry points, core modules, and the main data/control flow through the system.
Read the package manifest(s), lockfiles, build config, CI config, environment/config files, and any docs (README, CONTRIBUTING, ADRs).
Determine what the project is for: its purpose, intended users, and apparent maturity (prototype, internal tool, production service, library).
Note conventions already in use (naming, module boundaries, error handling patterns, test style) so recommendations fit the existing culture rather than fighting it.
Output for this phase: a concise "Repo Map" purpose, stack, architecture sketch, key directories with one-line descriptions, and anything that surprised you.
Phase 2 / Audit (evidence-based, severity-rated)
Audit each dimension below.
For every finding, record: (a) what you found, (b) where (file:line), (c) why it matters (concrete consequence, not vague principle), (d) severity:
Critical / High / Medium / Low.
• Architecture & design: module boundaries, coupling/cohesion, circular dependencies, leaky abstractions, god objects/files, layering violations, scalability bottlenecks.
• Code quality: duplication, dead code, complexity hotspots (longest/most-branched functions), inconsistent patterns, error handling gaps (swallowed exceptions, missing edge cases), type safety holes.
• Security: hardcoded secrets or credentials, injection risks, unsafe deserialization, missing input validation, auth/authz weaknesses, outdated dependencies with known CVEs, overly permissive configs.
• Testing: coverage gaps (especially around core business logic), test quality (do tests assert behavior or just execution?), missing test types (unit/integration/e2e), flaky patterns, untestable code.
• Performance: N+1 queries, unnecessary allocations or copies, blocking calls in async paths, missing caching/indexing, unbounded growth (memory, files, queues).
• Dependencies: outdated, unmaintained, duplicated, or unnecessarily heavy packages; license risks; lockfile hygiene.
• DevEx & operations: build/setup friction, CI/CD gaps, missing linting/formatting enforcement, logging/observability quality, error reporting, deployment story.
• Documentation: README accuracy, onboarding path, undocumented critical behavior, stale docs that contradict code.
Rules for this phase:
Prefer 15 high-confidence findings over 50 speculative ones.
Distinguish facts ("this function has no error handling: src/api/client.ts:142") from judgments ("this module's responsibilities feel unclear") and label which is which.
Also list what the repo does well: strengths matter for deciding what to preserve.
Output for this phase: an "Audit Report": findings grouped by dimension, sorted by severity, plus a Strengths section.
Don't forget to mention all the ugly parts that need utmost priority.
Phase 3 / Improvement Strategy
Synthesize the audit into a strategy:
Identify the 3–5 themes that explain most of the findings (e.g., "no enforced boundaries between layers," "error handling is ad hoc").
For each theme, propose a target state and the principle behind it.
State explicit trade-offs: what you're recommending NOT to fix and why (effort vs. payoff, risk, project maturity).
Define what "done" looks like — measurable signals (e.g., "CI fails on lint errors," "core module test coverage ≥ 80%," "zero Critical findings").
Phase 4 / Detailed Task Plan
Convert the strategy into an execution plan:
Break work into discrete tasks. Each task must include: Title and one-paragraph description
Files/areas affected
Acceptance criteria (how we verify it's done)
Effort estimate (S = <2h, M = half-day, L = 1–2 days, XL = needs breakdown)
Risk of the change itself (could it break things?)
Dependencies on other tasks
Order tasks into milestones:
Milestone 0
Safety net: anything needed before refactoring safely (tests around critical paths, CI gates, backups).
Milestone 1
Critical fixes: security and correctness issues.
Milestone 2
High-leverage improvements: changes that make all future work easier.
Milestone 3
Quality & polish: remaining medium/low items worth doing.
Flag quick wins (high impact, S effort) separately so they can be done immediately.
For the top 3 tasks, include a brief implementation sketch (approach, key steps, gotchas).
Final Deliverable Format
• Produce a single document with these sections:
• Executive Summary (≤10 sentences: overall health grade A–F with justification, top 3 risks, top 3 opportunities)
• Repo Map
• Audit Report
• Improvement Strategy
• Task Plan (milestones + task table + quick wins)
• Open Questions: anything you need from a human to decide (product intent, deprecation candidates, performance targets)
Constraints
Do NOT modify any code during this audit. Analysis only.
Do not pad the report. If a dimension is healthy, say so in one sentence and move on.
Calibrate to the project's maturity. Don't recommend enterprise-grade infrastructure for a weekend prototype unless the owner's goals demand it.
Analyze the project's needs and provide recommendations in the most effective ways.
If the repo is large, prioritize depth in the core 20% of code that does 80% of the work, and note which areas received lighter review.
Introducing Claude Fable 5: a Mythos-class model that we’ve made safe for general use.
Its capabilities exceed those of any model we’ve ever made generally available.
Got your hands on Claude Fable 5?
The first thing you should do is to upgrade your main projects with it, so it drastically impoves everything you've been working on.
Run this Audit & Project Improvement Prompt on each repo that's important to you (simply copy-paste it):
Repo Audit & Improvement Plan:
Prompt made by Claude Fable 5
You are a world-class principal-level software engineer and technical auditor. Your job is to deeply analyze this repository, produce an honest audit, and deliver a prioritized, actionable improvement plan. Work in the four phases below, in order. Do not skip ahead.
Ground every claim in actual files: cite file paths and line numbers. If you can't verify something, say so explicitly rather than guessing.
Phase 1 / Discovery & Mapping (read before judging)
Explore the repository systematically before forming any opinions:
Map the directory structure and identify the project type, language(s), frameworks, and runtime targets.
Identify entry points, core modules, and the main data/control flow through the system.
Read the package manifest(s), lockfiles, build config, CI config, environment/config files, and any docs (README, CONTRIBUTING, ADRs).
Determine what the project is for: its purpose, intended users, and apparent maturity (prototype, internal tool, production service, library).
Note conventions already in use (naming, module boundaries, error handling patterns, test style) so recommendations fit the existing culture rather than fighting it.
Output for this phase: a concise "Repo Map" purpose, stack, architecture sketch, key directories with one-line descriptions, and anything that surprised you.
Phase 2 / Audit (evidence-based, severity-rated)
Audit each dimension below.
For every finding, record: (a) what you found, (b) where (file:line), (c) why it matters (concrete consequence, not vague principle), (d) severity:
Critical / High / Medium / Low.
• Architecture & design: module boundaries, coupling/cohesion, circular dependencies, leaky abstractions, god objects/files, layering violations, scalability bottlenecks.
• Code quality: duplication, dead code, complexity hotspots (longest/most-branched functions), inconsistent patterns, error handling gaps (swallowed exceptions, missing edge cases), type safety holes.
• Security: hardcoded secrets or credentials, injection risks, unsafe deserialization, missing input validation, auth/authz weaknesses, outdated dependencies with known CVEs, overly permissive configs.
• Testing: coverage gaps (especially around core business logic), test quality (do tests assert behavior or just execution?), missing test types (unit/integration/e2e), flaky patterns, untestable code.
• Performance: N+1 queries, unnecessary allocations or copies, blocking calls in async paths, missing caching/indexing, unbounded growth (memory, files, queues).
• Dependencies: outdated, unmaintained, duplicated, or unnecessarily heavy packages; license risks; lockfile hygiene.
• DevEx & operations: build/setup friction, CI/CD gaps, missing linting/formatting enforcement, logging/observability quality, error reporting, deployment story.
• Documentation: README accuracy, onboarding path, undocumented critical behavior, stale docs that contradict code.
Rules for this phase:
Prefer 15 high-confidence findings over 50 speculative ones.
Distinguish facts ("this function has no error handling: src/api/client.ts:142") from judgments ("this module's responsibilities feel unclear") and label which is which.
Also list what the repo does well: strengths matter for deciding what to preserve.
Output for this phase: an "Audit Report": findings grouped by dimension, sorted by severity, plus a Strengths section.
Don't forget to mention all the ugly parts that need utmost priority.
Phase 3 / Improvement Strategy
Synthesize the audit into a strategy:
Identify the 3–5 themes that explain most of the findings (e.g., "no enforced boundaries between layers," "error handling is ad hoc").
For each theme, propose a target state and the principle behind it.
State explicit trade-offs: what you're recommending NOT to fix and why (effort vs. payoff, risk, project maturity).
Define what "done" looks like — measurable signals (e.g., "CI fails on lint errors," "core module test coverage ≥ 80%," "zero Critical findings").
Phase 4 / Detailed Task Plan
Convert the strategy into an execution plan:
Break work into discrete tasks. Each task must include: Title and one-paragraph description
Files/areas affected
Acceptance criteria (how we verify it's done)
Effort estimate (S = <2h, M = half-day, L = 1–2 days, XL = needs breakdown)
Risk of the change itself (could it break things?)
Dependencies on other tasks
Order tasks into milestones:
Milestone 0
Safety net: anything needed before refactoring safely (tests around critical paths, CI gates, backups).
Milestone 1
Critical fixes: security and correctness issues.
Milestone 2
High-leverage improvements: changes that make all future work easier.
Milestone 3
Quality & polish: remaining medium/low items worth doing.
Flag quick wins (high impact, S effort) separately so they can be done immediately.
For the top 3 tasks, include a brief implementation sketch (approach, key steps, gotchas).
Final Deliverable Format
• Produce a single document with these sections:
• Executive Summary (≤10 sentences: overall health grade A–F with justification, top 3 risks, top 3 opportunities)
• Repo Map
• Audit Report
• Improvement Strategy
• Task Plan (milestones + task table + quick wins)
• Open Questions: anything you need from a human to decide (product intent, deprecation candidates, performance targets)
Constraints
Do NOT modify any code during this audit. Analysis only.
Do not pad the report. If a dimension is healthy, say so in one sentence and move on.
Calibrate to the project's maturity. Don't recommend enterprise-grade infrastructure for a weekend prototype unless the owner's goals demand it.
Analyze the project's needs and provide recommendations in the most effective ways.
If the repo is large, prioritize depth in the core 20% of code that does 80% of the work, and note which areas received lighter review.
Introducing Claude Fable 5: a Mythos-class model that we’ve made safe for general use.
Its capabilities exceed those of any model we’ve ever made generally available.
Higgsfield Plugin for DaVinci Resolve is live.
Generate footage in your timeline, draw on a clip to edit, and apply AI-generated LUTs to your scene. Remove backgrounds, reframe, upscale to 4K.
Rebuild any shot to your camera, lens, and aperture on Cinema Studio.
i've been doing this more manually, getting the audit & plans done by Fable,
then feeding the audits and md files into Codex to build the stuff, but having a handoff md file between the two like this, and having Claude and Codex just work together is very smart
you'll save a lot this way, and get pretty much same output on 98% of the tasks
this is how to run claude fable 5 as your architect ( 20$ sub only ) + gpt 5.5 codex as your builder..
full system below:
the loop is : fable thinks... codex builds , the repo remembers and you judge, that simple..
the point of all this is that we are taking advantage that 5.5 is on a sub and it's fast enough, especially with /goal, and we using latest Anthropic model to be the judge/guidance..
step 1
>create the memory (one time): make docs/HANDOFF.md in your repo.
>codex updates it after every work session: what was built, what was decided + why, open disagreements, next slice. this file is why 30 min of fable is enough ..it reads state instead of asking you questions.
step 2 paste this to fable (every session)
>you are the ARCHITECT for [project]
>gpt 5.5 codex is the BUILDER
>you never write implementation code.
>your jobs:
(1) read the handoff below
(2) rule on every disagreement the builder raised: accept/reject/modify + one line why
(3) judge any results RAW against the gates in the docs and ignore the builder's narrative
(4) write the next slice spec: small enough for one PR, hard acceptance criteria, explicit out-of-scope, and force the builder to verify APIs/formats against reality before coding
(5) flag scope creep and goalpost-moving.. be blunt. disagree with me. end with a paste-ready block for the builder.
step 3 paste fable's block to codex with this /goal
/goal: execute the architect spec. rules:
PHASE 0 before any code, reply with your plan + every disagreement you have, with reasons, citing real files in the repo. silent compliance = failure. silent scope additions = failure.
PHASE 1 freeze shared contracts (schemas/interfaces) in docs/ first; after freeze they're read-only for everyone including you.
PHASE 2 spawn max 3-4 lane agents on modules that don't import each other, plus ONE reviewer agent that never writes feature code: it checks every lane against the spec + tests + frozen docs and returns APPROVE or a numbered defect list. nothing merges without approve. then: commit + push each slice, update docs/HANDOFF.md with raw results only tables and numbers, no interpretation, no 'promising'. verdicts belong to the architect and the human."
step 4 repeat codex works hours.. you spend fable minutes on judgment only: arbitration, evidence review, next specs, kill/continue calls. one fable session per work block.
the 5 rules that make it actually work
>repo docs are the memory not in HANDOFF.md = didn't happen
>the builder never grades its own work
>disagreement is mandatory
>freeze success criteria BEFORE results exist, never edit after
>spend architect time on judgment, builder time on typing
>the architect is the edge and the builder is the hands. the repo is the brain.. think of it that way..
bookmark this. you will need it.. you really wont need to pay hundreds in API tokens if you do this way
yea i saw your tweet Sammy, and me wanna check whether I was on Fable the whole time when doing this,
i ran 14 audits and never got degraded
however saw many cases where people got stopped or got degraded in Fable, especially in biology-related stuff or security audits
but here with this prompt never got those flags you gotta point out to local repos tho to be safe