Claude Code Headless: An Always-On Local Schedule

The Stack

Tested Against

Steps

1. 1

   Write the headless script and the cron line

   claude -p runs one prompt non-interactively. --permission-mode dontAsk auto-denies anything not pre-approved instead of hanging on a prompt no one will answer. Schedule it with OS cron.

   cat > overnight-summary.sh <<'EOF'
   #!/usr/bin/env bash
   cd ~/code/myrepo
   claude -p "Summarize the commits pushed since yesterday and flag anything risky." --permission-mode dontAsk
   EOF
   echo "wrote overnight-summary.sh; cron line: 0 7 * * 1-5 ~/bin/overnight-summary.sh"

2. 2

   What CI checks: the cron is well-formed and the call is non-interactive

   CI confirms the cron line is a valid 5-field expression and the script carries a `claude -p` call in a non-interactive permission mode (dontAsk, a real mode per code.claude.com/docs). No model runs.

   cat > checkheadless.mjs <<'EOF'
   import { readFileSync } from 'node:fs';
   const sh = readFileSync('overnight-summary.sh','utf8');
   const fields = (process.argv[2] || '').trim().split(' ').filter(Boolean);
   let ok = true;
   function check(label, cond){ console.log(label + ': ' + (cond ? 'yes' : 'NO')); if(!cond) ok=false; }
   check('script has claude -p', sh.includes('claude -p'));
   check('non-interactive (dontAsk)', sh.includes('--permission-mode dontAsk'));
   check('cron is 5-field', fields.length === 5);
   if(!ok){ console.log('headless schedule check FAILED'); process.exit(1); }
   console.log('headless schedule check OK');
   EOF
   node checkheadless.mjs "0 7 * * 1-5"

3. 3

   Let cron run it (the model step, not checked by CI)

   When cron fires the script, claude -p invokes the model to write the summary. That output is non-deterministic and fenced: CI verifies the schedule and the command shape, never the summary.