fix(chat): stop the transcript settle effect from looping

src/features/workspaces/components/ai-chat/ai-chat-transcript-recovery.ts

@@ -1,5 +1,10 @@
 import type { AiChatMessage } from "#/features/workspaces/components/ai-chat/types";
 
+/** Whether a store snapshot already matches the local transcript exactly. */
+export function transcriptsEqual(local: AiChatMessage[], stored: AiChatMessage[]) {
+	return JSON.stringify(local) === JSON.stringify(stored);
+}
+
 /** Whether a settled store snapshot proves an uncertain transport kept running. */
 export function serverTranscriptAdvanced(local: AiChatMessage[], stored: AiChatMessage[]) {
 	const localTail = local.at(-1);

src/features/workspaces/components/ai-chat/useWorkspaceAiChat.test.ts

@@ -1,7 +1,24 @@
 import { describe, expect, it } from "vitest";
 
 import type { AiChatMessage } from "#/features/workspaces/components/ai-chat/types";
-import { serverTranscriptAdvanced } from "#/features/workspaces/components/ai-chat/ai-chat-transcript-recovery";
+import {
+	serverTranscriptAdvanced,
+	transcriptsEqual,
+} from "#/features/workspaces/components/ai-chat/ai-chat-transcript-recovery";
+
+describe("transcript equality", () => {
+	it("treats a fresh copy of the same transcript as equal", () => {
+		const messages = [userMessage("user-1", "hello"), assistantMessage("reply-1", "hi")];
+		// The settle effect stops here: it never re-copies an unchanged snapshot.
+		expect(transcriptsEqual(messages, [...messages])).toBe(true);
+	});
+
+	it("sees durable metadata missing from the local row as a difference", () => {
+		const local = assistantMessage("reply-1", "partial");
+		const stored = { ...local, metadata: { turnStatus: "interrupted" } };
+		expect(transcriptsEqual([local], [stored])).toBe(false);
+	});
+});
 
 describe("server transcript recovery", () => {
 	it("keeps an unpersisted user tail after a refused request", () => {

src/features/workspaces/components/ai-chat/useWorkspaceAiChat.ts

@@ -13,7 +13,10 @@ import {
 import type { SerializedAiChatThreadTranscript } from "#/features/workspaces/ai/chat/functions";
 import { deriveAiChatPresentation } from "#/features/workspaces/components/ai-chat/ai-chat-display-state";
 import { isAiChatUsageLimitResponse } from "#/features/workspaces/components/ai-chat/ai-chat-error-state";
-import { serverTranscriptAdvanced } from "#/features/workspaces/components/ai-chat/ai-chat-transcript-recovery";
+import {
+	serverTranscriptAdvanced,
+	transcriptsEqual,
+} from "#/features/workspaces/components/ai-chat/ai-chat-transcript-recovery";
 import {
 	parseCodemodeActivityEvent,
 	type AiChatLiveCodemodeActivity,
@@ -175,6 +178,14 @@ export function useWorkspaceAiChat({
 		// Once Postgres says the turn is settled, its complete snapshot wins. IDs
 		// and lengths are insufficient: the SDK's local row can share an id with
 		// the durable row while lacking its interrupted/error metadata.
+		//
+		// Compare before setting. The SDK copies the array on every set, so an
+		// unconditional set here changes `messages` identity, re-fires this effect
+		// (which lists `messages`), and the two feed each other until React throws
+		// error #185.
+		if (transcriptsEqual(messages, transcriptData)) {
+			return;
+		}
 		setMessages(transcriptData);
 		if (recoveredAfterError) {
 			clearError();