feat: render pipeline optimization (Phase 0)

- Persistent Chromium browser instance with auto-reconnect (WP-02)
- FastAPI lifespan hooks for browser startup/shutdown (WP-03)
- Self-hosted WOFF2 fonts via base64 embedding, remove Google Fonts CDN (WP-01)
- Fix pre-existing lint issues (unused imports, f-string placeholders)

Eliminates ~1.5s browser spawn overhead and ~0.4s font CDN round-trip
per card render. Target: per-card render from ~3s to <1s.

Refs: #88, #89, #90

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/main.py

@@ -1,5 +1,6 @@
 import logging
 import os
+from contextlib import asynccontextmanager
 from datetime import datetime
 
 from fastapi import FastAPI, Request
@@ -17,6 +18,7 @@ logging.basicConfig(
 # from fastapi.templating import Jinja2Templates
 
 from .db_engine import db
+from .routers_v2.players import get_browser, shutdown_browser
 from .routers_v2 import (
     current,
     awards,
@@ -51,8 +53,19 @@ from .routers_v2 import (
     scout_claims,
 )
 
+
+@asynccontextmanager
+async def lifespan(app):
+    # Startup: warm up the persistent Chromium browser
+    await get_browser()
+    yield
+    # Shutdown: clean up browser and playwright
+    await shutdown_browser()
+
+
 app = FastAPI(
     # root_path='/api',
+    lifespan=lifespan,
     responses={404: {"description": "Not found"}},
     docs_url="/api/docs",
     redoc_url="/api/redoc",
@@ -114,4 +127,4 @@ async def get_docs(req: Request):
 
 @app.get("/api/openapi.json", include_in_schema=False)
 async def openapi():
-    return get_openapi(title="Paper Dynasty API", version=f"0.1.1", routes=app.routes)
+    return get_openapi(title="Paper Dynasty API", version="0.1.1", routes=app.routes)

app/routers_v2/players.py

@@ -9,7 +9,7 @@ from typing import Optional, List, Literal
 import logging
 import pydantic
 from pandas import DataFrame
-from playwright.async_api import async_playwright
+from playwright.async_api import async_playwright, Browser, Playwright
 
 from ..card_creation import get_batter_card_data, get_pitcher_card_data
 from ..db_engine import (
@@ -31,6 +31,57 @@ from ..db_engine import (
 from ..db_helpers import upsert_players
 from ..dependencies import oauth2_scheme, valid_token
 
+# ---------------------------------------------------------------------------
+# Persistent browser instance (WP-02)
+# ---------------------------------------------------------------------------
+
+_browser: Browser | None = None
+_playwright: Playwright | None = None
+
+
+async def get_browser() -> Browser:
+    """Get or create persistent Chromium browser instance.
+
+    Reuses a single browser across all card renders, eliminating the ~1-1.5s
+    per-request launch/teardown overhead. Automatically reconnects if the
+    browser process has died.
+    """
+    global _browser, _playwright
+    if _browser is None or not _browser.is_connected():
+        if _playwright is not None:
+            try:
+                await _playwright.stop()
+            except Exception:
+                pass
+        _playwright = await async_playwright().start()
+        _browser = await _playwright.chromium.launch(
+            args=["--no-sandbox", "--disable-dev-shm-usage"]
+        )
+    return _browser
+
+
+async def shutdown_browser():
+    """Clean shutdown of the persistent browser.
+
+    Called by the FastAPI lifespan handler on application exit so the
+    Chromium process is not left orphaned.
+    """
+    global _browser, _playwright
+    if _browser:
+        try:
+            await _browser.close()
+        except Exception:
+            pass
+        _browser = None
+    if _playwright:
+        try:
+            await _playwright.stop()
+        except Exception:
+            pass
+        _playwright = None
+
+
+# ---------------------------------------------------------------------------
 # Franchise normalization: Convert city+team names to city-agnostic team names
 # This enables cross-era player matching (e.g., 'Oakland Athletics' -> 'Athletics')
 FRANCHISE_NORMALIZE = {
@@ -144,7 +195,7 @@ async def get_players(
 ):
     all_players = Player.select()
     if all_players.count() == 0:
-        raise HTTPException(status_code=404, detail=f"There are no players to filter")
+        raise HTTPException(status_code=404, detail="There are no players to filter")
 
     if name is not None:
         all_players = all_players.where(fn.Lower(Player.p_name) == name.lower())
@@ -674,7 +725,7 @@ async def get_batter_card(
         )
 
     headers = {"Cache-Control": "public, max-age=86400"}
-    filename = (
+    _filename = (
         f"{this_player.description} {this_player.p_name} {card_type} {d}-v{variant}"
     )
     if (
@@ -799,16 +850,17 @@ async def get_batter_card(
     logging.debug(f"body:\n{html_response.body.decode('UTF-8')}")
 
     file_path = f"storage/cards/cardset-{this_player.cardset.id}/{card_type}/{player_id}-{d}-v{variant}.png"
-    async with async_playwright() as p:
-        browser = await p.chromium.launch()
-        page = await browser.new_page()
+    browser = await get_browser()
+    page = await browser.new_page(viewport={"width": 1280, "height": 720})
+    try:
         await page.set_content(html_response.body.decode("UTF-8"))
         await page.screenshot(
             path=file_path,
             type="png",
             clip={"x": 0.0, "y": 0, "width": 1200, "height": 600},
         )
-        await browser.close()
+    finally:
+        await page.close()
 
     # hti = Html2Image(
     #     browser='chrome',

storage/templates/player_card.html

@@ -2,9 +2,6 @@
 <html lang="en">
 <head>
     {% include 'style.html' %}
-    <link rel="preconnect" href="https://fonts.googleapis.com">
-    <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
-    <link href="https://fonts.googleapis.com/css2?family=Open+Sans:wght@300;400;700&family=Source+Sans+3:wght@400;700&display=swap" rel="stylesheet">
 </head>
 <body>
     <div id="fullCard" style="width: 1200px; height: 600px;">