- Create BudgetWarning primitive payload (75%, 90%, 95% thresholds)
- Add threshold tracking to ThreadBudget with triggered_thresholds set
- Change consume() to return (budget, crossed_thresholds) tuple
- Wire warning injection in LLM router when thresholds crossed
- Add 15 new tests for threshold detection and warning injection
Agents now receive BudgetWarning messages when approaching their token limit,
allowing them to design contingencies (summarize, escalate, save state).
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
