fix(blender): send a real User-Agent so Cloudflare stops blocking the add-on

Submitting failed with a 403 before the request reached the server:
Cloudflare error 1010, a browser-signature ban. Python's urllib
identifies itself as "Python-urllib/3.x", which is exactly the scripted
signature that rule targets. The AE panel was unaffected because curl
sends curl/8.x, and the worker because .NET sends its own.

Verified against the live zone, same request and token, only the agent
changed: Python-urllib/3.11 gets 403 while VFXReviewBlender/1.0.1 gets
200 — as do curl and a browser agent.

Naming the tool is also the honest thing: the studio's logs should say
what is calling them, and the version travels with it.

A Cloudflare block is also no longer reported to the artist as a wall of
JSON about browser signatures — it says the firewall stopped the request
before it reached the server, and to ask the pipeline TD.

Add-on 1.0.1.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

BlenderPanel/README.md

@@ -86,3 +86,11 @@ nothing in the UI sets them today — one place for render settings is the point
 **Exit code 0 with no frames is treated as a failure.** Blender exits cleanly
 when a frame range is empty or an output path is unwritable, so the worker
 checks that frames were actually saved before reporting success.
+
+**The add-on sends its own User-Agent** (`VFXReviewBlender/<version>`). Python's
+`urllib` otherwise identifies itself as `Python-urllib/3.x`, which Cloudflare
+blocks outright as a scripted signature — a 403 with error 1010 before the
+request ever reaches the server. Verified against the live zone: `Python-urllib`
+gets 403, the add-on's own agent gets 200. If a future Cloudflare rule blocks it
+anyway, the add-on says so in plain language rather than showing the raw JSON,
+and the fix is a WAF allow rule on the agent or on `/api/ext/*`.

BlenderPanel/vfxreview_submit.py

@@ -1,7 +1,7 @@
 bl_info = {
     "name": "VFXReview — Submit Render",
     "author": "Two Tales",
-    "version": (1, 0, 0),
+    "version": (1, 0, 1),
     "blender": (3, 6, 0),
     "location": "Properties > Output > VFXReview",
     "description": "Queue this .blend on the studio render farm instead of rendering locally",
@@ -48,6 +48,10 @@ def prefs():
     return bpy.context.preferences.addons[__name__].preferences
 
 
+ADDON_VERSION = ".".join(str(n) for n in bl_info["version"])
+USER_AGENT = "VFXReviewBlender/%s (Blender %s)" % (ADDON_VERSION, bpy.app.version_string)
+
+
 # ── API ───────────────────────────────────────────────────────────────────────
 
 def api_request(path, payload=None, method="GET"):
@@ -61,6 +65,11 @@ def api_request(path, payload=None, method="GET"):
     req = urllib.request.Request(url, data=data, method=method)
     req.add_header("Authorization", "Bearer " + p.api_key)
     req.add_header("Accept", "application/json")
+    # urllib identifies itself as "Python-urllib/3.x" by default, which
+    # Cloudflare blocks outright as a scripted signature (error 1010). Sending a
+    # real name for this tool is also the honest thing: the studio's logs should
+    # say what is calling them.
+    req.add_header("User-Agent", USER_AGENT)
     if data:
         req.add_header("Content-Type", "application/json")
 
@@ -70,9 +79,21 @@ def api_request(path, payload=None, method="GET"):
     except urllib.error.HTTPError as e:
         body = e.read().decode("utf-8", "replace")
         try:
-            message = json.loads(body).get("error", body)
+            parsed = json.loads(body)
         except Exception:
-            message = body
+            parsed = {}
+
+        # A Cloudflare block is not a pipeline error and reads nothing like one,
+        # so say what it actually is rather than showing the artist a wall of
+        # JSON about browser signatures.
+        if parsed.get("cloudflare_error") or parsed.get("error_code") == 1010:
+            raise RuntimeError(
+                "Blocked by Cloudflare before reaching the server (error %s). "
+                "The studio's firewall needs to allow this add-on — ask the pipeline TD."
+                % parsed.get("error_code", e.code)
+            )
+
+        message = parsed.get("error", body) if parsed else body
         raise RuntimeError("Server said %s: %s" % (e.code, message))
     except urllib.error.URLError as e:
         raise RuntimeError("Could not reach %s (%s)" % (url, e.reason))