Merge pull request #3470 from omer-koren/fix/thinking-block-modified-recovery

fix(session-recovery): add thinking_block_modified error detection and recovery

src/hooks/session-recovery/detect-error-type.test.ts

@@ -36,6 +36,31 @@ describe("detectErrorType", () => {
     expect(result).toBe("thinking_disabled_violation")
   })
 
+  it("#given a Bedrock thinking block modified error #when detecting #then returns thinking_block_modified", () => {
+    //#given
+    const error = {
+      message:
+        "undefined: The model returned the following errors: messages.17.content.28: `thinking` or `redacted_thinking` blocks in the latest assistant message cannot be modified. These blocks must remain as they were in the original response.",
+    }
+
+    //#when
+    const result = detectErrorType(error)
+
+    //#then
+    expect(result).toBe("thinking_block_modified")
+  })
+
+  it("#given a simple thinking block modified error #when detecting #then returns thinking_block_modified", () => {
+    //#given
+    const error = { message: "thinking blocks cannot be modified" }
+
+    //#when
+    const result = detectErrorType(error)
+
+    //#then
+    expect(result).toBe("thinking_block_modified")
+  })
+
   it("#given an unrecognized error #when detecting #then returns null", () => {
     //#given
     const error = { message: "some random error" }

src/hooks/session-recovery/detect-error-type.ts

@@ -2,6 +2,7 @@ export type RecoveryErrorType =
   | "tool_result_missing"
   | "thinking_block_order"
   | "thinking_disabled_violation"
+  | "thinking_block_modified"
   | "assistant_prefill_unsupported"
   | "unavailable_tool"
   | null
@@ -77,6 +78,11 @@ export function detectErrorType(error: unknown): RecoveryErrorType {
       return "thinking_block_order"
     }
 
+    // Thinking block signature corruption (Bedrock compaction)
+    if (message.includes("thinking") && message.includes("cannot be modified")) {
+      return "thinking_block_modified"
+    }
+
     if (message.includes("thinking is disabled") && message.includes("cannot contain")) {
       return "thinking_disabled_violation"
     }

src/hooks/session-recovery/hook.ts

@@ -99,6 +99,7 @@ export function createSessionRecoveryHook(ctx: PluginInput, options?: SessionRec
         unavailable_tool: "Tool Recovery",
         thinking_block_order: "Thinking Block Recovery",
         thinking_disabled_violation: "Thinking Strip Recovery",
+        thinking_block_modified: "Thinking Block Recovery",
         "assistant_prefill_unsupported": "Prefill Unsupported",
       }
       const toastMessages: Record<RecoveryErrorType & string, string> = {
@@ -106,6 +107,7 @@ export function createSessionRecoveryHook(ctx: PluginInput, options?: SessionRec
         unavailable_tool: "Recovering from unavailable tool call...",
         thinking_block_order: "Fixing message structure...",
         thinking_disabled_violation: "Stripping thinking blocks...",
+        thinking_block_modified: "Stripping corrupted thinking blocks...",
         "assistant_prefill_unsupported": "Prefill not supported; continuing without recovery.",
       }
 
@@ -142,6 +144,13 @@ export function createSessionRecoveryHook(ctx: PluginInput, options?: SessionRec
           const resumeConfig = extractResumeConfig(lastUser, sessionID)
           await resumeSession(ctx.client, resumeConfig)
         }
+      } else if (errorType === "thinking_block_modified") {
+        success = await recoverThinkingDisabledViolation(ctx.client, sessionID, failedMsg)
+        if (success && experimental?.auto_resume) {
+          const lastUser = findLastUserMessage(msgs ?? [])
+          const resumeConfig = extractResumeConfig(lastUser, sessionID)
+          await resumeSession(ctx.client, resumeConfig)
+        }
       } else if (errorType === "assistant_prefill_unsupported") {
         success = false
       }