fix(coding-agent): replaced JSON string equality checks with deep equality

- Changed provider delta input comparisons in `buildResponsesDeltaInput` to use `Bun.deepEquals` instead of stringified JSON checks.
- Updated session message diffing to return early on length changes and compare normalized entries with deep equality.
- Replaced JSON-string assertions in the issue-966 repro test with `Bun.deepEquals` for stable equality checks.

packages/ai/src/providers/openai-responses-shared.ts

@@ -1240,13 +1240,13 @@ export function buildResponsesDeltaInput<TItem>(
 	if (!Array.isArray(previous.input) || !Array.isArray(current.input)) return null;
 	const previousWithoutInput = { ...previous, input: undefined, client_metadata: undefined };
 	const currentWithoutInput = { ...current, input: undefined, client_metadata: undefined };
-	if (JSON.stringify(previousWithoutInput) !== JSON.stringify(currentWithoutInput)) {
+	if (!Bun.deepEquals(previousWithoutInput, currentWithoutInput)) {
 		return null;
 	}
 	const baseline = [...previous.input, ...(previousResponseItems ?? [])];
 	if (current.input.length <= baseline.length) return null;
 	for (let index = 0; index < baseline.length; index += 1) {
-		if (JSON.stringify(baseline[index]) !== JSON.stringify(current.input[index])) {
+		if (!Bun.deepEquals(baseline[index], current.input[index])) {
 			return null;
 		}
 	}

packages/coding-agent/src/session/agent-session.ts

@@ -8709,9 +8709,13 @@ export class AgentSession {
 	}
 
 	#didSessionMessagesChange(previousMessages: AgentMessage[], nextMessages: AgentMessage[]): boolean {
-		return (
-			JSON.stringify(previousMessages.map(message => this.#normalizeSessionMessageForProviderReplay(message))) !==
-			JSON.stringify(nextMessages.map(message => this.#normalizeSessionMessageForProviderReplay(message)))
+		if (previousMessages.length !== nextMessages.length) return true;
+		return previousMessages.some(
+			(message, i) =>
+				!Bun.deepEquals(
+					this.#normalizeSessionMessageForProviderReplay(message),
+					this.#normalizeSessionMessageForProviderReplay(nextMessages[i]),
+				),
 		);
 	}
 

packages/coding-agent/src/session/session-loader.ts

@@ -56,9 +56,7 @@ async function resolvePersistedBlobRefs(value: unknown, blobStore: BlobStore, ke
 	}
 
 	if (Array.isArray(value)) {
-		await Promise.all(
-			value.map(item => resolvePersistedBlobRefs(item, blobStore, key)),
-		);
+		await Promise.all(value.map(item => resolvePersistedBlobRefs(item, blobStore, key)));
 		return;
 	}
 

packages/coding-agent/test/issue-966-repro.test.ts

@@ -30,7 +30,7 @@ try {
 		diffCached: true,
 	});
 	const firstStage = await git.diff.changedFiles(dir, { cached: true });
-	if (JSON.stringify(firstStage) !== JSON.stringify(["new-file.txt"])) {
+	if (!Bun.deepEquals(firstStage, ["new-file.txt"])) {
 		throw new Error("unexpected first stage: " + JSON.stringify(firstStage));
 	}
 	await git.commit(dir, "feat: add new file");
@@ -39,16 +39,16 @@ try {
 		diffCached: true,
 	});
 	const secondStage = await git.diff.changedFiles(dir, { cached: true });
-	if (JSON.stringify(secondStage) !== JSON.stringify(["tracked.txt"])) {
+	if (!Bun.deepEquals(secondStage, ["tracked.txt"])) {
 		throw new Error("unexpected second stage: " + JSON.stringify(secondStage));
 	}
 	await git.commit(dir, "fix: update tracked file");
 	const log = (await $\`git log --format=%s -2\`.cwd(dir).text()).trim().split("\\n");
-	if (JSON.stringify(log) !== JSON.stringify(["fix: update tracked file", "feat: add new file"])) {
+	if (!Bun.deepEquals(log, ["fix: update tracked file", "feat: add new file"])) {
 		throw new Error("unexpected log: " + JSON.stringify(log));
 	}
 	const summary = await git.status.summary(dir);
-	if (JSON.stringify(summary) !== JSON.stringify({ staged: 0, unstaged: 0, untracked: 0 })) {
+	if (!Bun.deepEquals(summary, { staged: 0, unstaged: 0, untracked: 0 })) {
 		throw new Error("unexpected status: " + JSON.stringify(summary));
 	}
 } finally {