fix: revert progress to previous text when final matches last progress

When the final result text is identical to the last progress update,
edit the progress message back to the previous progress text to avoid
showing the same content twice in Discord.

src/message-turn-controller.ts

@@ -26,6 +26,7 @@ export class MessageTurnController {
   private hadError = false;
   private producedDeliverySucceeded = true;
   private latestProgressText: string | null = null;
+  private previousProgressText: string | null = null;
   private latestProgressRendered: string | null = null;
   private progressMessageId: string | null = null;
   private progressStartedAt: number | null = null;
@@ -115,7 +116,7 @@ export class MessageTurnController {
     }
 
     if (text) {
-      await this.finalizeProgressMessage();
+      await this.finalizeProgressMessage(text);
       await this.deliverFinalText(text);
     } else if (raw) {
       logger.info(
@@ -214,7 +215,8 @@ export class MessageTurnController {
 
     const suffix = `\n\n${elapsedParts.join(' ')}`;
     const maxText = 2000 - TASK_STATUS_MESSAGE_PREFIX.length - suffix.length;
-    const truncated = text.length > maxText ? text.slice(0, maxText - 1) + '…' : text;
+    const truncated =
+      text.length > maxText ? text.slice(0, maxText - 1) + '…' : text;
     return `${TASK_STATUS_MESSAGE_PREFIX}${truncated}${suffix}`;
   }
 
@@ -227,6 +229,7 @@ export class MessageTurnController {
   private resetProgressState(): void {
     this.clearProgressTicker();
     this.latestProgressText = null;
+    this.previousProgressText = null;
     this.latestProgressRendered = null;
     this.progressMessageId = null;
     this.progressStartedAt = null;
@@ -290,7 +293,7 @@ export class MessageTurnController {
     }, 10_000);
   }
 
-  private async finalizeProgressMessage(): Promise<void> {
+  private async finalizeProgressMessage(finalText?: string): Promise<void> {
     logger.info(
       {
         chatJid: this.options.chatJid,
@@ -302,7 +305,28 @@ export class MessageTurnController {
       },
       'Finalizing tracked progress message',
     );
-    await this.syncTrackedProgressMessage();
+    // If the last progress text matches the final result, revert to the
+    // previous progress so the same text doesn't appear twice in chat.
+    if (
+      finalText &&
+      this.latestProgressText === finalText &&
+      this.previousProgressText &&
+      this.progressMessageId &&
+      this.options.channel.editMessage
+    ) {
+      try {
+        const rendered = this.renderProgressMessage(this.previousProgressText);
+        await this.options.channel.editMessage(
+          this.options.chatJid,
+          this.progressMessageId,
+          rendered,
+        );
+      } catch {
+        // Best effort
+      }
+    } else {
+      await this.syncTrackedProgressMessage();
+    }
     this.resetProgressState();
   }
 
@@ -338,6 +362,7 @@ export class MessageTurnController {
       this.progressStartedAt = Date.now();
     }
     this.latestProgressTextForFinal = text;
+    this.previousProgressText = this.latestProgressText;
     this.latestProgressText = text;
     const rendered = this.renderProgressMessage(text);