Claude Code v2.1.77–78: Agent Frontmatter, StopFailure Hook, Plugin State Persistence
Releasebot·high signal
Released March 17–18, 2026. v2.1.78 adds `effort`, `maxTurns`, and `disallowedTools` frontmatter to agent definition files enabling per-agent behavior tuning without code changes. New `StopFailure` hook fires on API errors (rate limits, auth failures), and `${CLAUDE_PLUGIN_DATA}` variable persists plugin state across updates. v2.1.77 raised default output to 64k tokens and upper bound to 128k for Opus 4.6/Sonnet 4.6, plus `allowRead` sandbox setting for selective filesystem access restoration.