What
Return values from a hook are validated per event rather than trusted. A subagent spawn hook may only rewrite the model. A pre-tool-use hook must keep the tool envelope's keys intact. A prompt submission hook may return replacement text or a drop string. The question component is refused as a render target outright, because its answer authorises an action; a plugin can add context around it with a notice instead.
Details
- The full event list a module may hook is PreToolUse, tool.call, tool.describe, ui.render, ui.resolve, agent.spawn, prompt.submit, prompt.section, turn.start, turn.step, turn.complete and engine.create.
- Validation is structural to the hooks engine, not tied to a separate flag.
Evidence
is drawn by the engine alone; its answer authorises an action. A plugin adds context with $.ui.notice
Strings lifted out of the shipped bundle, so the claim above can be checked against them.