API cost tracking: capture per-job spend from Claude Code output

[FrederikHandberg]

Problem

Zero instrumentation on Anthropic API spend. No cost per job in YAML, no daily total on dashboard, no threshold alert. A single autoresearch job could cost $5 or $50 — currently no way to know.

Fix

Claude Code prints a cost summary at the end of each session:

Total cost: $0.47

1. In worker.py, after job completion, grep the tmux pane output for the cost pattern:

   import re
   cost_match = re.search(r'Total cost: \$([0-9.]+)', pane_output)
   if cost_match:
       yq -i f'.cost_usd = {cost_match.group(1)}' job_yaml

2. Add cost_usd field to job YAML schema
3. Aggregate daily/weekly totals in morning report
4. Dashboard shows per-job cost and running total
5. Alert (ntfy) if daily spend > threshold (configurable, start with $10)

Acceptance Criteria

• cost_usd field in every completed job YAML
• Morning report shows yesterday's total API spend
• Dashboard job list shows cost per job
• Alert fires if daily cost exceeds threshold
• Threshold configurable via env var or config file

Context

From Jensen limitation audit (2026-03-22). Workstream: WS-001.