Interface: MessageDeniedContext

Defined in: src/core/agent/middleware/errors.ts:38

MessageDeniedError — typed error thrown by Agent.run() when a messageMiddleware returns deny(reason).

Pattern: Typed Error (the PolicyHaltError shape, for the same reason). Role: Surface layer for the message boundary. The stage writes the refusal to scope; Agent.finalizeResult translates it here, so a caller can instanceof it and route on .phase / .middleware. Emits: N/A — agentfootprint.middleware.decision fires from the stage at the moment the refusal is decided.

Why a refusal is not returned as an answer

At the 'input' phase there is no model to tell: the message never reached one, so there is nothing in the run for a denial to become. At the 'output' phase there IS an answer, and the middleware has just refused to release it — handing the caller a string in its place is the one substitution a caller must never be able to make silently. Both phases therefore raise, exactly the way a policy halt does.

What it deliberately does not carry

Never the refused content. A middleware that suppressed an answer would be undone by an error object that carried the answer out anyway. The content stays where the run put it — in the commit log, under whatever redaction the run configured.

Example

try {
    await agent.run({ message: userText });
  } catch (e) {
    if (e instanceof MessageDeniedError) {
      console.log(`${e.middleware} refused this ${e.phase}: ${e.reason}`);
    } else throw e;
  }

Properties

middleware

readonly middleware: string

Defined in: src/core/agent/middleware/errors.ts:44

name of the middleware that returned deny.

phase

readonly phase: "input" | "output"

Defined in: src/core/agent/middleware/errors.ts:42

Which boundary refused.

reason

readonly reason: string

Defined in: src/core/agent/middleware/errors.ts:40

The refusal text the middleware returned.