Add 5 new rules to the agent spawn prompt: read-before-write, verify-after-write, no-partial-work, message-when-blocked, and backward-compatibility. Adds verification checklist before marking tasks done. Addresses recurring issues with agents skipping call site updates, leaving partial implementations, and not escalating blockers. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>