From ba779d836736426c93d7608ebcee0b05fed6b8fd Mon Sep 17 00:00:00 2001
From: Vincent Koc <vincentkoc@ieee.org>
Date: Thu, 18 Jun 2026 23:45:47 +0800
Subject: [PATCH] refactor(agents): remove unused thinking recovery sanitizer

---
 .../embedded-agent-runner/thinking.test.ts    | 46 +------------------
 src/agents/embedded-agent-runner/thinking.ts  | 33 -------------
 2 files changed, 1 insertion(+), 78 deletions(-)

diff --git a/src/agents/embedded-agent-runner/thinking.test.ts b/src/agents/embedded-agent-runner/thinking.test.ts
index 794a182ec0ae..688772014c01 100644
--- a/src/agents/embedded-agent-runner/thinking.test.ts
+++ b/src/agents/embedded-agent-runner/thinking.test.ts
@@ -10,7 +10,6 @@ import {
   dropReasoningFromHistory,
   dropThinkingBlocks,
   isAssistantMessageWithContent,
-  sanitizeThinkingForRecovery,
   stripInvalidThinkingSignatures,
   stripStaleThinkingSignaturesForCompactionReplay,
   wrapAnthropicStreamWithRecovery,
@@ -406,50 +405,7 @@ describe("stripInvalidThinkingSignatures", () => {
   });
 });
 
-describe("sanitizeThinkingForRecovery", () => {
-  it("drops the latest assistant message when the thinking block is unsigned", () => {
-    const messages = castAgentMessages([
-      { role: "user", content: "hello" },
-      {
-        role: "assistant",
-        content: [{ type: "thinking", thinking: "partial" }],
-      },
-    ]);
-
-    const result = sanitizeThinkingForRecovery(messages);
-    expect(result.messages).toEqual([messages[0]]);
-    expect(result.prefill).toBe(false);
-  });
-
-  it("preserves later turns when dropping an incomplete assistant message", () => {
-    const messages = castAgentMessages([
-      { role: "user", content: "hello" },
-      {
-        role: "assistant",
-        content: [{ type: "thinking", thinking: "partial" }],
-      },
-      { role: "user", content: "follow up" },
-    ]);
-
-    const result = sanitizeThinkingForRecovery(messages);
-    expect(result.messages).toEqual([messages[0], messages[2]]);
-    expect(result.prefill).toBe(false);
-  });
-
-  it("marks signed thinking without text as a prefill recovery case", () => {
-    const messages = castAgentMessages([
-      { role: "user", content: "hello" },
-      {
-        role: "assistant",
-        content: [{ type: "thinking", thinking: "complete", thinkingSignature: "sig" }],
-      },
-    ]);
-
-    const result = sanitizeThinkingForRecovery(messages);
-    expect(result.messages).toBe(messages);
-    expect(result.prefill).toBe(true);
-  });
-
+describe("assessLastAssistantMessage", () => {
   it("marks signed thinking with an empty text block as incomplete text", () => {
     const message = castAgentMessage({
       role: "assistant",
diff --git a/src/agents/embedded-agent-runner/thinking.ts b/src/agents/embedded-agent-runner/thinking.ts
index 2a97bd09ce9e..210c508d6c72 100644
--- a/src/agents/embedded-agent-runner/thinking.ts
+++ b/src/agents/embedded-agent-runner/thinking.ts
@@ -534,39 +534,6 @@ export function assessLastAssistantMessage(message: AgentMessage): RecoveryAsses
   return "valid";
 }
 
-export function sanitizeThinkingForRecovery(messages: AgentMessage[]): {
-  messages: AgentMessage[];
-  prefill: boolean;
-} {
-  if (messages.length === 0) {
-    return { messages, prefill: false };
-  }
-
-  let lastAssistantIndex = -1;
-  for (let index = messages.length - 1; index >= 0; index -= 1) {
-    if ((messages[index] as { role?: unknown }).role === "assistant") {
-      lastAssistantIndex = index;
-      break;
-    }
-  }
-  if (lastAssistantIndex === -1) {
-    return { messages, prefill: false };
-  }
-
-  const assessment = assessLastAssistantMessage(messages[lastAssistantIndex]);
-  if (assessment === "valid") {
-    return { messages, prefill: false };
-  }
-  if (assessment === "incomplete-text") {
-    return { messages, prefill: true };
-  }
-
-  return {
-    messages: [...messages.slice(0, lastAssistantIndex), ...messages.slice(lastAssistantIndex + 1)],
-    prefill: false,
-  };
-}
-
 function shouldRecoverAnthropicThinkingError(
   error: unknown,
   sessionMeta: RecoverySessionMeta,