api.on("message_received", async (event) => {
  if (isPromptInjection(event.content)) {
    return { block: true, notifyUser: "Message blocked." };
  }
});

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<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

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<sub>(2/5) Greptile learns from your feedback when you react with thumbs up/down!</sub>

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