When frontmatter validation fails, the step is never written to CAS, so
isFirstVisit remains true on the next run. Both agent-claude-code and
agent-hermes gated session cache lookup behind !isFirstVisit, which
caused them to start a fresh session (and a new worktree) instead of
resuming the one that already has all the work done.
Changes:
- Remove the isFirstVisit guard from both adapters so they always check
the session cache.
- When isFirstVisit + cache hit (frontmatter-only failure), send a
minimal correction prompt via buildFrontmatterRetryPrompt() instead
of re-sending the full initial prompt — the session already has full
context, we just need the agent to re-output correctly formatted
frontmatter.
- Add buildFrontmatterRetryPrompt to util-agent with tests.
Fixes#139
