When the agent's first run output fails frontmatter extraction, the
retry loop (via options.continue) would replace agentResult entirely,
causing the 1-turn continuation detail to overwrite the original
multi-turn detail containing all tool-call history.
Now we capture primaryDetailHash from the first run and always use it
for the persisted StepNode, regardless of how many retries occur.
Fixes#439
xiaoju
759c784267