fix: resolve /api/lab/result 500 and /api/lab/precons/install-batch 400

- GET /api/lab/result: Starlette's JSONResponse uses allow_nan=False,
  so NaN/Infinity floats from simulation output cause a ValueError crash.
  Add _sanitize_floats() to replace non-finite floats with null before
  returning. Also wrap json.load in try/except for better error reporting.

- POST /api/lab/precons/install-batch: Frontend sends {"names": [...]}
  but backend expected {"fileNames": [...]}. Accept both field names.

- POST /api/lab/precons/install: Same mismatch — frontend sends {"name"}
  but backend expected {"fileName"}. Accept both field names.

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

routes/lab.py

@@ -19,6 +19,7 @@ from __future__ import annotations
 
 import glob
 import json
+import math
 import os
 import re
 import threading
@@ -52,6 +53,19 @@ from routes.shared import (
 router = APIRouter(tags=["lab"])
 
 
+def _sanitize_floats(obj):
+    """Replace NaN/Infinity with None so JSONResponse (allow_nan=False) won't crash."""
+    if isinstance(obj, float):
+        if math.isnan(obj) or math.isinf(obj):
+            return None
+        return obj
+    if isinstance(obj, dict):
+        return {k: _sanitize_floats(v) for k, v in obj.items()}
+    if isinstance(obj, list):
+        return [_sanitize_floats(v) for v in obj]
+    return obj
+
+
 @router.post("/api/lab/start", response_model=StartResponse)
 async def start_batch(req: StartRequest, background_tasks: BackgroundTasks):
     """Start a new batch simulation run."""
@@ -162,8 +176,12 @@ async def get_result(batchId: Optional[str] = None):
         raise HTTPException(500, state.error)
     if not state.result_path or not os.path.exists(state.result_path):
         raise HTTPException(500, "Result file not found")
-    with open(state.result_path, "r", encoding="utf-8") as f:
-        data = json.load(f)
+    try:
+        with open(state.result_path, "r", encoding="utf-8") as f:
+            data = json.load(f)
+    except (json.JSONDecodeError, OSError) as e:
+        raise HTTPException(500, f"Failed to read result file: {e}")
+    data = _sanitize_floats(data)
     return JSONResponse(content=data)
 
 

routes/precon.py

@@ -31,9 +31,9 @@ async def list_precons():
 @router.post("/api/lab/precons/install")
 async def install_precon(req: dict):
     """Install a precon deck to the Forge decks directory.
-    Body: {"fileName": "Elven_Empire.dck"}
+    Body: {"fileName": "Elven_Empire.dck"} or {"name": "Elven_Empire.dck"}
     """
-    file_name = req.get("fileName", "")
+    file_name = req.get("fileName", "") or req.get("name", "")
     if not file_name:
         raise HTTPException(400, "fileName is required")
 
@@ -60,9 +60,9 @@ async def install_precon(req: dict):
 @router.post("/api/lab/precons/install-batch")
 async def install_precons_batch(req: dict):
     """Install multiple precon decks at once.
-    Body: {"fileNames": ["Elven_Empire.dck", "Necron_Dynasties.dck"]}
+    Body: {"fileNames": ["Elven_Empire.dck", ...]} or {"names": ["Elven_Empire.dck", ...]}
     """
-    file_names = req.get("fileNames", [])
+    file_names = req.get("fileNames", []) or req.get("names", [])
     if not file_names:
         raise HTTPException(400, "fileNames list is required")