The typed lifecycle hook registrars and the decision semantics core applies to each hook result. Part of the Plugin SDK overview.

Events and lifecycle

See Plugin hooks for examples, common hook names, and guard semantics.

Hook decision semantics

before_install is a plugin-runtime lifecycle hook, not the operator install policy surface. Use security.installPolicy when an allow/warn/block decision must cover CLI and Gateway-backed install or update paths.

• before_tool_call: returning { block: true } is terminal. Once any handler sets it, lower-priority handlers are skipped.
• before_tool_call: returning { block: false } is treated as no decision (same as omitting block), not as an override.
• before_install: returning { block: true } is terminal. Once any handler sets it, lower-priority handlers are skipped.
• before_install: returning { block: false } is treated as no decision (same as omitting block), not as an override.
• reply_dispatch: returning { handled: true, ... } is terminal. Once any handler claims dispatch, lower-priority handlers and the default model dispatch path are skipped.
• message_sending: returning { cancel: true } is terminal. Once any handler sets it, lower-priority handlers are skipped.
• message_sending: returning { cancel: false } is treated as no decision (same as omitting cancel), not as an override.
• message_received: use the typed threadId field when you need inbound thread/topic routing. Keep metadata for channel-specific extras.
• message_sending: use typed replyToId / threadId routing fields before falling back to channel-specific metadata.
• gateway_start: use ctx.config, ctx.workspaceDir, and ctx.getCron?.() for gateway-owned startup state instead of relying on internal gateway:startup hooks. Cron may still be loading at this point.
• cron_reconciled: rebuild a full external cron projection after startup or scheduler reload. It includes reason and the effective enabled state, including enabled: false, while ctx.getCron?.() returns the exact reconciled scheduler. Pass ctx.abortSignal into durable projection work; it aborts when that scheduler snapshot is superseded or the Gateway closes.
• cron_changed: observe gateway-owned cron lifecycle changes. scheduled and removed events are post-commit reconciliation hints, not an ordered delta log. A scheduled event's event.nextRunAtMs is absent when the job has no next wake; a removed event still carries the deleted job snapshot.

External wake schedulers should debounce or coalesce cron_changed events, then reread the full durable view from the scheduler last captured by cron_reconciled. Do not adopt the scheduler from a cron_changed context: a detached hint from an older scheduler can overlap a later reload.

Use cron_reconciled as the full-snapshot trigger for durable state loaded at Gateway startup or scheduler replacement. It is not replayed for a plugin-only hot reload. Observation handlers run in parallel, and fire-and-forget dispatches can overlap, so consumers must not depend on event completion order. Keep Apus as the source of truth for due checks and execution.

For a single-flight adapter with durable replacement, retry/backoff, and clean shutdown, see Safe external cron projection.