#10539: feat(hooks): add blocking capability to message_received hookFeat/message received blocking

## Summary This PR enhances the `message_received` hook to support **blocking incoming messages** before they reach the agent. This enables security plugins to intercept and reject malicious messages (e.g., prompt injection attempts). **Author:** ClawForge Team ## Changes ### 1. New Result Type (`src/plugins/types.ts`) - Added `PluginHookMessageReceivedResult` with `block`, `blockReason`, `notifyUser`, `notifyAgent`, `threatLevel`, and `auditMetadata` fields ### 2. Hook Implementation (`src/plugins/hooks.ts`) - Changed `runMessageReceived` from `runVoidHook` to `runModifyingHook` - Added result merging logic ### 3. Dispatch Logic (`src/auto-reply/reply/dispatch-from-config.ts`) - Now awaits hook result instead of fire-and-forget - Checks for `block: true` and returns early - Sends `notifyUser` message when blocking ## Backward Compatibility ✅ Fully backward compatible - Existing void handlers return `undefined` → message allowed - Only handlers explicitly returning `{ block: true }` cause blocking - Errors in hooks cause fail-open behavior ## Use Case Enables security plugins like prompt injection detection: ```typescript api.on("message_received", async (event) => { if (isPromptInjection(event.content)) { return { block: true, notifyUser: "Message blocked." }; } }); <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> - Extends the `message_received` plugin hook so handlers can return a structured result that can block inbound messages. - Updates the hook runner implementation to execute `message_received` via the modifying-hook path and merge results. - Updates `dispatchReplyFromConfig` to await `message_received` and short-circuit message processing (optionally notifying the user) when `block: true` is returned. - Adds the `PluginHookMessageReceivedResult` type and updates the hook handler map signature accordingly. <h3>Confidence Score: 3/5</h3> - This PR is close, but has a couple of type-level issues that should be fixed before merging. - Core behavior changes are localized and appear consistent with the goal (block on hook result), but `runMessageReceived` currently calls `runModifyingHook` with incorrect generic parameters and the new result type is not re-exported from `src/plugins/hooks.ts`, which can break compilation and/or consumer imports. - src/plugins/hooks.ts <!-- greptile_other_comments_section --> _{(2/5) Greptile learns from your feedback when you react with thumbs up/down!} <!-- /greptile_comment -->