add error handling to render pipeline, graceful portrait fallback

blue_archive/gacha.py

@@ -267,16 +267,29 @@ class BlueArchiveGacha(commands.Cog):
 
         # Render result image
         spark = user_state["spark"]
+        try:
             async with ctx.typing():
                 img_bytes = await render_pull(pulls, banner_name, spark)
+        except Exception as e:
+            log.exception("Render failed")
+            try:
+                await teaser.delete()
+            except (discord.NotFound, discord.Forbidden):
+                pass
+            await ctx.reply(f"Render failed: {e}")
+            return
 
-        # Send image only — the picture says it all
+        # Send image only
+        try:
             file = discord.File(img_bytes, filename="gacha_result.png")
             try:
                 await teaser.delete()
             except (discord.NotFound, discord.Forbidden):
                 pass
             await ctx.reply(file=file)
+        except Exception as e:
+            log.exception("Failed to send result image")
+            await ctx.reply(f"Failed to send result: {e}")
 
     @commands.command(name="spark")
     async def spark(self, ctx: commands.Context, *, character_name: str = "") -> None:

blue_archive/gacha_renderer.py

@@ -201,9 +201,15 @@ async def render_pull(
     _draw_footer(draw, spark_count)
 
     # ── Fetch all portraits ─────────────────────────────────────────────
-    async with aiohttp.ClientSession() as session:
+    timeout = aiohttp.ClientTimeout(total=60, connect=10)
+    async with aiohttp.ClientSession(timeout=timeout) as session:
         portrait_tasks = [_fetch_portrait(session, p) for p in pulls]
-        portraits = await asyncio.gather(*portrait_tasks)
+        portraits = await asyncio.gather(*portrait_tasks, return_exceptions=True)
+        # Unwrap exceptions: failed fetches become None
+        for i, result in enumerate(portraits):
+            if isinstance(result, Exception):
+                log.warning("Portrait %d (%s) failed: %s", pulls[i]["Id"], pulls[i]["Name"], result)
+                portraits[i] = None
 
     # ── Draw cards in grid ──────────────────────────────────────────────
     for idx, (student, portrait) in enumerate(zip(pulls, portraits)):