fix: guard anthropic refusal trigger

src/agents/pi-embedded-runner/run.ts

@@ -51,6 +51,18 @@ import { describeUnknownError } from "./utils.js";
 
 type ApiKeyInfo = ResolvedProviderAuth;
 
+// Avoid Anthropic's refusal test token poisoning session transcripts.
+const ANTHROPIC_MAGIC_STRING_TRIGGER_REFUSAL = "ANTHROPIC_MAGIC_STRING_TRIGGER_REFUSAL";
+const ANTHROPIC_MAGIC_STRING_REPLACEMENT = "ANTHROPIC MAGIC STRING TRIGGER REFUSAL (redacted)";
+
+function scrubAnthropicRefusalMagic(prompt: string): string {
+  if (!prompt.includes(ANTHROPIC_MAGIC_STRING_TRIGGER_REFUSAL)) return prompt;
+  return prompt.replaceAll(
+    ANTHROPIC_MAGIC_STRING_TRIGGER_REFUSAL,
+    ANTHROPIC_MAGIC_STRING_REPLACEMENT,
+  );
+}
+
 export async function runEmbeddedPiAgent(
   params: RunEmbeddedPiAgentParams,
 ): Promise<EmbeddedPiRunResult> {
@@ -211,6 +223,9 @@ export async function runEmbeddedPiAgent(
           attemptedThinking.add(thinkLevel);
           await fs.mkdir(resolvedWorkspace, { recursive: true });
 
+          const prompt =
+            provider === "anthropic" ? scrubAnthropicRefusalMagic(params.prompt) : params.prompt;
+
           const attempt = await runEmbeddedAttempt({
             sessionId: params.sessionId,
             sessionKey: params.sessionKey,
@@ -228,7 +243,7 @@ export async function runEmbeddedPiAgent(
             agentDir,
             config: params.config,
             skillsSnapshot: params.skillsSnapshot,
-            prompt: params.prompt,
+            prompt,
             images: params.images,
             provider,
             modelId,