Repomix + Fable 5: Pack a Repo for a Long-Context Review

The Stack

Tested Against

Prerequisites

• Node 20+ (npx repomix@latest)
• An Anthropic API key for claude-fable-5 (only for the fenced review)

Steps

1. 1

   Pack the repo into one file

   In your project: npx repomix@latest. It walks the repo, respects .gitignore, and writes repomix-output.xml with a file tree, contents, and token counts. Then send that file as the user message to claude-fable-5 and ask for, say, a dependency-risk audit.

2. 2

   What CI checks: repomix actually packs the repo into well-formed XML

   CI scaffolds a small fixture repo, runs npx repomix@latest --style xml, and confirms the output file exists, is non-empty well-formed XML, and contains the file manifest. Fully deterministic, no key, because packing never calls a model. Fable's review is fenced.

   mkdir -p sample/src
   cat > sample/src/index.js <<'EOF'
   export function add(a, b) { return a + b }
   EOF
   cat > sample/README.md <<'EOF'
   # Sample
   A tiny repo for packing.
   EOF
   ( cd sample && npx --yes repomix@latest --style xml >/dev/null 2>&1 )
   cat > checkrepomix.mjs <<'EOF'
   import { existsSync, readFileSync } from 'node:fs';
   const out = 'sample/repomix-output.xml';
   let ok = true;
   function check(label, cond){ console.log(label + ': ' + (cond ? 'yes' : 'NO')); if(!cond) ok=false; }
   check('packed output file exists', existsSync(out));
   const xml = existsSync(out) ? readFileSync(out, 'utf8') : '';
   check('output has repomix XML structure', xml.includes('<file_summary>') && xml.includes('<file path='));
   check('output contains the file manifest', xml.includes('src/index.js'));
   if(!ok){ console.log('repomix pack check FAILED'); process.exit(1); }
   console.log('repomix pack check OK: packed the repo into well-formed XML');
   EOF
   node checkrepomix.mjs

3. 3

   Send it to Fable for review (the model step, not checked by CI)

   Hand the packed file to claude-fable-5 and ask for a whole-system review. That runs the model and is non-deterministic, so CI never claims it. The badge covers the pack, not the review.