fix(insta-render): fonts.ready 대기 + PNG 비어있음 검증 (렌더 known-issue 해결)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

services/insta-render/card_renderer.py

@@ -151,8 +151,11 @@ async def _render_slate_locked(slate: dict, slate_id: int, template: str) -> Lis
                 html_path = f.name
             try:
                 await page.goto(f"file://{html_path}", wait_until="networkidle")
+                await page.evaluate("document.fonts.ready")   # 웹폰트 로딩 완료까지 대기
                 out_path = os.path.join(out_dir, f"{spec['page_no']:02d}.png")
                 await page.screenshot(path=out_path, full_page=False, omit_background=False)
+                if os.path.getsize(out_path) < 1000:          # 빈/깨진 PNG 방어
+                    raise RuntimeError(f"rendered PNG too small: {out_path}")
                 paths.append(out_path)
             finally:
                 try:

services/insta-render/tests/test_worker.py

@@ -1,10 +1,13 @@
 """worker.py — Redis BLPOP + webhook 단위 테스트."""
 import json
+import os
+from pathlib import Path
 import pytest
 import httpx
 from unittest.mock import AsyncMock, patch
 
 import worker
+from card_renderer import render_slate, init_browser, shutdown_browser
 
 
 @pytest.fixture
@@ -179,6 +182,28 @@ async def test_poll_once_calls_fail_on_exception(monkeypatch):
     fake_queue.ack.assert_not_awaited()
 
 
+@pytest.mark.asyncio
+async def test_render_produces_nonempty_1080x1350(tmp_path, monkeypatch):
+    """Phase 2 — fonts.ready 대기 + PNG 비어있음 검증: 10장 모두 > 1000 bytes."""
+    import card_renderer as _cr
+    templates_dir = str(Path(__file__).resolve().parent.parent / "templates")
+    monkeypatch.setattr(_cr, "CARD_TEMPLATE_DIR", templates_dir)
+    monkeypatch.setattr(_cr, "INSTA_MEDIA_ROOT", str(tmp_path))
+    await init_browser()
+    try:
+        slate = {
+            "cover_copy": {"headline": "헤드라인", "body": "서브", "accent_color": "#0F62FE"},
+            "body_copies": [{"headline": f"포인트{i}", "body": "본문"} for i in range(8)],
+            "cta_copy": {"headline": "요약", "body": "마무리", "cta": "팔로우"},
+        }
+        paths = await render_slate(slate, slate_id=99999)
+        assert len(paths) == 10
+        for p in paths:
+            assert os.path.getsize(p) > 1000          # 비어있지 않음
+    finally:
+        await shutdown_browser()
+
+
 @pytest.mark.asyncio
 async def test_poll_once_returns_false_on_timeout(monkeypatch):
     """F6 — dequeue가 None 반환(타임아웃)이면 False 리턴, ack/fail 안 부름."""