From 0031bf7a11ed5ebe37b500a71d572a1b5e0f2062 Mon Sep 17 00:00:00 2001
From: justsisyphus <justsisyphus@users.noreply.github.com>
Date: Wed, 21 Jan 2026 11:00:30 +0900
Subject: [PATCH] fix(session-recovery): reorder error detection to prevent
 false tool_result_missing match

Anthropic's extended thinking error messages contain 'tool_use' and 'tool_result'
in the documentation URL text, causing incorrect detection as tool_result_missing
instead of thinking_block_order.

Fix: Check thinking_block_order BEFORE tool_result_missing.
---
 src/hooks/session-recovery/index.test.ts | 20 ++++++++++++++++++++
 src/hooks/session-recovery/index.ts      | 11 +++++++----
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/src/hooks/session-recovery/index.test.ts b/src/hooks/session-recovery/index.test.ts
index 15b9e17d..97edc18f 100644
--- a/src/hooks/session-recovery/index.test.ts
+++ b/src/hooks/session-recovery/index.test.ts
@@ -199,5 +199,25 @@ describe("detectErrorType", () => {
       // #then should return thinking_block_order
       expect(result).toBe("thinking_block_order")
     })
+
+    it("should detect thinking_block_order even when error message contains tool_use/tool_result in docs URL", () => {
+      // #given Anthropic's extended thinking error with tool_use/tool_result in the documentation text
+      const error = {
+        error: {
+          type: "invalid_request_error",
+          message:
+            "messages.1.content.0.type: Expected `thinking` or `redacted_thinking`, but found `text`. " +
+            "When `thinking` is enabled, a final `assistant` message must start with a thinking block " +
+            "(preceeding the lastmost set of `tool_use` and `tool_result` blocks). " +
+            "We recommend you include thinking blocks from previous turns.",
+        },
+      }
+
+      // #when detectErrorType is called
+      const result = detectErrorType(error)
+
+      // #then should return thinking_block_order (NOT tool_result_missing)
+      expect(result).toBe("thinking_block_order")
+    })
   })
 })
diff --git a/src/hooks/session-recovery/index.ts b/src/hooks/session-recovery/index.ts
index 68ddb3fd..79f31fc5 100644
--- a/src/hooks/session-recovery/index.ts
+++ b/src/hooks/session-recovery/index.ts
@@ -125,10 +125,9 @@ function extractMessageIndex(error: unknown): number | null {
 export function detectErrorType(error: unknown): RecoveryErrorType {
   const message = getErrorMessage(error)
 
-  if (message.includes("tool_use") && message.includes("tool_result")) {
-    return "tool_result_missing"
-  }
-
+  // IMPORTANT: Check thinking_block_order BEFORE tool_result_missing
+  // because Anthropic's extended thinking error messages contain "tool_use" and "tool_result"
+  // in the documentation URL, which would incorrectly match tool_result_missing
   if (
     message.includes("thinking") &&
     (message.includes("first block") ||
@@ -145,6 +144,10 @@ export function detectErrorType(error: unknown): RecoveryErrorType {
     return "thinking_disabled_violation"
   }
 
+  if (message.includes("tool_use") && message.includes("tool_result")) {
+    return "tool_result_missing"
+  }
+
   return null
 }