From e5814b12c6253d952c9cb9ebaf4671a56656d650 Mon Sep 17 00:00:00 2001
From: Jeff Emmett <jeffemmett@gmail.com>
Date: Mon, 16 Mar 2026 20:51:05 -0700
Subject: [PATCH] fix(rsplat): use fal.ai response_url for result fetch, add
 poll logging

The result fetch was constructing its own URL instead of using the
response_url returned by fal.ai's status poll. This caused 422 errors.
Now captures response_url from poll and uses it for result retrieval.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 server/index.ts | 23 +++++++++++------------
 1 file changed, 11 insertions(+), 12 deletions(-)

diff --git a/server/index.ts b/server/index.ts
index 1c7f369..4da1324 100644
--- a/server/index.ts
+++ b/server/index.ts
@@ -790,6 +790,7 @@ async function process3DGenJob(job: Gen3DJob) {
 
 		// 3. Poll for completion (up to 8 min — Hunyuan3D with textures can take 3-5 min)
 		const deadline = Date.now() + 480_000;
+		let responseUrl = "";
 		let completed = false;
 		while (Date.now() < deadline) {
 			await new Promise((r) => setTimeout(r, 3000));
@@ -798,9 +799,11 @@ async function process3DGenJob(job: Gen3DJob) {
 				{ headers: falHeaders },
 			);
 			if (!statusRes.ok) continue;
-			const status = await statusRes.json() as { status: string };
-			if (status.status === "COMPLETED") { completed = true; break; }
-			if (status.status === "FAILED") {
+			const statusData = await statusRes.json() as { status: string; response_url?: string };
+			console.log(`[3d-gen] Poll ${job.id}: status=${statusData.status}`);
+			if (statusData.response_url) responseUrl = statusData.response_url;
+			if (statusData.status === "COMPLETED") { completed = true; break; }
+			if (statusData.status === "FAILED") {
 				job.status = "failed";
 				job.error = "3D generation failed on fal.ai";
 				job.completedAt = Date.now();
@@ -814,20 +817,16 @@ async function process3DGenJob(job: Gen3DJob) {
 			return;
 		}
 
-		// 4. Fetch result (retry once after 3s on transient failure)
-		let resultRes = await fetch(
-			`https://queue.fal.run/${MODEL}/requests/${request_id}`,
-			{ headers: falHeaders },
-		);
+		// 4. Fetch result using response_url from status (with fallback)
+		const resultUrl = responseUrl || `https://queue.fal.run/${MODEL}/requests/${request_id}`;
+		console.log(`[3d-gen] Fetching result from: ${resultUrl}`);
+		let resultRes = await fetch(resultUrl, { headers: falHeaders });
 		if (!resultRes.ok) {
 			console.warn(`[3d-gen] Result fetch failed (status=${resultRes.status}), retrying in 3s...`);
 			const errBody = await resultRes.text().catch(() => "");
 			console.warn(`[3d-gen] Result error body:`, errBody);
 			await new Promise((r) => setTimeout(r, 3000));
-			resultRes = await fetch(
-				`https://queue.fal.run/${MODEL}/requests/${request_id}`,
-				{ headers: falHeaders },
-			);
+			resultRes = await fetch(resultUrl, { headers: falHeaders });
 		}
 		if (!resultRes.ok) {
 			const errBody = await resultRes.text().catch(() => "");