From 84a309d669f69ca7c9a43e997fc694d192459f31 Mon Sep 17 00:00:00 2001
From: David Luzar <5153846+dwelle@users.noreply.github.com>
Date: Wed, 21 Jan 2026 14:07:23 +0100
Subject: [PATCH] fix: ttd 429 error handling (#10680)

---
 .../components/TTDDialog/TTDDialogOutput.tsx  |   4 +-
 .../TTDDialog/hooks/useTextGeneration.ts      | 128 +++++++-----------
 packages/excalidraw/locales/en.json           |   6 +-
 3 files changed, 57 insertions(+), 81 deletions(-)

diff --git a/packages/excalidraw/components/TTDDialog/TTDDialogOutput.tsx b/packages/excalidraw/components/TTDDialog/TTDDialogOutput.tsx
index f19d459633..443ccc4d3e 100644
--- a/packages/excalidraw/components/TTDDialog/TTDDialogOutput.tsx
+++ b/packages/excalidraw/components/TTDDialog/TTDDialogOutput.tsx
@@ -37,7 +37,9 @@ export const TTDDialogOutput = ({
               {t("ttd.error")}
             </div>
             <div className="ttd-dialog-output-error-message">
-              {hideErrorDetails ? t("ttd.errorMermaidSyntax") : error.message}
+              {hideErrorDetails
+                ? t("chat.errors.mermaidParseError")
+                : error.message}
             </div>
           </div>
         </div>
diff --git a/packages/excalidraw/components/TTDDialog/hooks/useTextGeneration.ts b/packages/excalidraw/components/TTDDialog/hooks/useTextGeneration.ts
index 47c91584e8..e31847ae0c 100644
--- a/packages/excalidraw/components/TTDDialog/hooks/useTextGeneration.ts
+++ b/packages/excalidraw/components/TTDDialog/hooks/useTextGeneration.ts
@@ -63,31 +63,6 @@ export const useTextGeneration = ({
     return true;
   };
 
-  const getReadableErrorMsg = (msg: string) => {
-    try {
-      const content = JSON.parse(msg);
-
-      const innerMessages = JSON.parse(content.message);
-
-      return innerMessages
-        .map((oneMsg: { message: string }) => oneMsg.message)
-        .join("\n");
-    } catch (err) {
-      return msg;
-    }
-  };
-
-  const handleError = (error: Error, errorType: "parse" | "network") => {
-    if (errorType === "parse") {
-      trackEvent("ai", "mermaid parse failed", "ttd");
-    }
-
-    const msg = getReadableErrorMsg(error.message);
-
-    setAssistantError(msg, errorType);
-    setError(error);
-  };
-
   const onGenerate: TTTDDialog.OnGenerate = async ({
     prompt,
     isRepairFlow = false,
@@ -165,6 +140,34 @@ export const useTextGeneration = ({
         setRateLimits({ rateLimit, rateLimitRemaining });
       }
 
+      if (error?.status === 429 || rateLimitRemaining === 0) {
+        setChatHistory((chatHistory) => {
+          if (error?.status === 429) {
+            chatHistory = removeLastAssistantMessage(chatHistory);
+          }
+
+          chatHistory = {
+            ...chatHistory,
+            messages: chatHistory.messages.filter(
+              (msg) =>
+                msg.type !== "warning" ||
+                msg.warningType === "rateLimitExceeded" ||
+                msg.warningType === "messageLimitExceeded",
+            ),
+          };
+          const messages = addMessages(chatHistory, [
+            {
+              type: "warning",
+              warningType:
+                rateLimitRemaining === 0
+                  ? "messageLimitExceeded"
+                  : "rateLimitExceeded",
+            },
+          ]);
+          return messages;
+        });
+      }
+
       if (error) {
         const isAborted =
           error.name === "AbortError" ||
@@ -176,63 +179,34 @@ export const useTextGeneration = ({
           return;
         }
 
-        if (error.status === 429) {
-          setChatHistory((prev) => {
-            const chatHistory = removeLastAssistantMessage(prev);
-
-            return {
-              ...chatHistory,
-              messages: chatHistory.messages.filter(
-                (msg) =>
-                  msg.type !== "warning" ||
-                  msg.warningType === "rateLimitExceeded" ||
-                  msg.warningType === "messageLimitExceeded",
-              ),
-            };
-          });
-
-          setChatHistory((chatHistory) => {
-            return addMessages(chatHistory, [
-              {
-                type: "warning",
-                warningType:
-                  rateLimitRemaining === 0
-                    ? "messageLimitExceeded"
-                    : "rateLimitExceeded",
-              },
-            ]);
-          });
-
-          return;
-        } else if (rateLimitRemaining === 0) {
-          setChatHistory((chatHistory) => {
-            chatHistory = {
-              ...chatHistory,
-              messages: chatHistory.messages.filter(
-                (msg) =>
-                  msg.type !== "warning" ||
-                  msg.warningType === "rateLimitExceeded" ||
-                  msg.warningType === "messageLimitExceeded",
-              ),
-            };
-            return addMessages(chatHistory, [
-              {
-                type: "warning",
-                warningType: "messageLimitExceeded",
-              },
-            ]);
-          });
+        const _error = new Error(
+          error.message || t("chat.errors.requestFailed"),
+        );
+        if (error.status !== 429) {
+          setAssistantError(_error.message, "network");
         }
+        setError(_error);
 
-        handleError(error as Error, "network");
         return;
       }
 
-      await parseMermaidToExcalidraw(generatedResponse ?? "");
-
-      trackEvent("ai", "mermaid parse success", "ttd");
-    } catch (error: unknown) {
-      handleError(error as Error, "parse");
+      try {
+        await parseMermaidToExcalidraw(generatedResponse ?? "");
+        trackEvent("ai", "mermaid parse success", "ttd");
+      } catch (error: any) {
+        trackEvent("ai", "mermaid parse failed", "ttd");
+        const _error = new Error(
+          error.message || t("chat.errors.mermaidParseError"),
+        );
+        setAssistantError(_error.message, "parse");
+        setError(_error);
+      }
+    } catch (error: any) {
+      const _error = new Error(
+        error.message || t("chat.errors.generationFailed"),
+      );
+      setAssistantError(_error.message, "other");
+      setError(_error);
     } finally {
       streamingAbortControllerRef.current = null;
     }
diff --git a/packages/excalidraw/locales/en.json b/packages/excalidraw/locales/en.json
index dd69162c3f..b66485c73d 100644
--- a/packages/excalidraw/locales/en.json
+++ b/packages/excalidraw/locales/en.json
@@ -617,8 +617,7 @@
     "inputPlaceholder": "Write Mermaid diagram defintion here..."
   },
   "ttd": {
-    "error": "Error!",
-    "errorMermaidSyntax": "Mermaid syntax error"
+    "error": "Error!"
   },
   "chat": {
     "inputPlaceholder": "Start typing your diagram idea here... ({{shortcut}} for new line)",
@@ -653,7 +652,8 @@
       "fixInMermaid": "Edit Mermaid manually →",
       "aiRepair": "Regenerate (auto-fix) →",
       "requestAborted": "Request aborted",
-      "requestFailed": "Request failed"
+      "requestFailed": "Request failed",
+      "mermaidParseError": "Mermaid syntax error"
     },
     "rateLimit": {
       "messageLimit": "You've hit your AI limit on the free plan. Try out Excalidraw+ for more or come back tomorrow.",