The session-start hook approach didn't work — Claude Code's TUI
overwrites stdout before the agent sees it, and the hook only fires
when the agent calls it as a tool.
Instead, inject mission context directly into the composed system
prompt via build_runtime_prompt(). When mission.json is active in
CWD, the agent gets mission name, ID, milestone progress, and
mandatory first-action instructions in its initial context.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Jason Woltje
221afe94d9