perf: avoid duplicate transcript idempotency scans

extensions/codex/src/app-server/transcript-mirror.ts

@@ -186,6 +186,7 @@ export async function mirrorCodexAppServerTranscript(params: {
       const { messageId, message: appendedMessage } = await appendSessionTranscriptMessage({
         transcriptPath: params.sessionFile,
         message: messageToAppend,
+        idempotencyLookup: idempotencyKey ? "caller-checked" : "scan",
         config: params.config,
       });
       if (appendedMessage.role === "user") {

src/config/sessions/transcript-append.ts

@@ -241,6 +241,8 @@ type AppendSessionTranscriptMessageParams<TMessage = unknown> = {
   sessionId?: string;
   cwd?: string;
   useRawWhenLinear?: boolean;
+  /** Use only when the caller already checked this idempotency key under the session write lock. */
+  idempotencyLookup?: "scan" | "caller-checked";
   config?: OpenClawConfig;
 };
 
@@ -305,9 +307,10 @@ async function appendSessionTranscriptMessageLocked<TMessage>(
     ...(params.cwd ? { cwd: params.cwd } : {}),
   });
   const idempotencyKey = readMessageIdempotencyKey(params.message);
-  const existing = idempotencyKey
-    ? await findTranscriptMessageByIdempotencyKey<TMessage>(params.transcriptPath, idempotencyKey)
-    : undefined;
+  const existing =
+    idempotencyKey && params.idempotencyLookup !== "caller-checked"
+      ? await findTranscriptMessageByIdempotencyKey<TMessage>(params.transcriptPath, idempotencyKey)
+      : undefined;
   if (existing) {
     return { ...existing, appended: false };
   }

src/config/sessions/transcript.ts

@@ -353,6 +353,7 @@ export async function appendExactAssistantMessageToSessionTranscript(params: {
             return await appendSessionTranscriptMessage({
               transcriptPath: sessionFile,
               message,
+              idempotencyLookup: explicitIdempotencyKey ? "caller-checked" : "scan",
               config: params.config,
             });
           },