feat: implement PostHog analytics for canvas events and user identification

Author: atyrode

src/backend/main.py

@@ -6,7 +6,18 @@
 from fastapi.responses import FileResponse
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.staticfiles import StaticFiles
-from fastapi.templating import Jinja2Templates
+from api_analytics.fastapi import Analytics
+from dotenv import load_dotenv
+import posthog
+
+load_dotenv()
+
+POSTHOG_API_KEY = os.environ.get("VITE_PUBLIC_POSTHOG_KEY")
+POSTHOG_HOST = os.environ.get("VITE_PUBLIC_POSTHOG_HOST")
+
+if POSTHOG_API_KEY:
+    posthog.project_api_key = POSTHOG_API_KEY
+    posthog.host = POSTHOG_HOST
 
 from db import init_db
 from config import STATIC_DIR, ASSETS_DIR
@@ -24,6 +35,9 @@ async def lifespan(_: FastAPI):
 
 app = FastAPI(lifespan=lifespan)
 
+# Add analytics middleware
+app.add_middleware(Analytics, api_key="ea6d92e3-51d7-48f0-a327-8a38869ade13")
+
 # CORS middleware setup
 app.add_middleware(
     CORSMiddleware,
@@ -33,7 +47,6 @@ async def lifespan(_: FastAPI):
     allow_headers=["*"],
 )
 
-print("ASSETS_DIR", ASSETS_DIR)
 app.mount("/assets", StaticFiles(directory=ASSETS_DIR), name="assets")
 
 @app.get("/")

src/backend/requirements.txt

@@ -6,4 +6,6 @@ asyncpg
 python-dotenv
 PyJWT
 requests
-sqlalchemy
+api-analytics[fastapi]
+sqlalchemy
+posthog

src/backend/routers/canvas.py

@@ -1,11 +1,12 @@
 import json
 import jwt
 from typing import Dict, Any
-from fastapi import APIRouter, HTTPException, Depends
+from fastapi import APIRouter, HTTPException, Depends, Request
 from fastapi.responses import JSONResponse
 
 from dependencies import SessionData, require_auth
 from db import store_canvas_data, get_canvas_data
+import posthog
 
 canvas_router = APIRouter()
 
@@ -19,14 +20,49 @@ def get_default_canvas_data():
             detail=f"Failed to load default canvas: {str(e)}"
         )
 
+@canvas_router.get("/default")
+async def get_default_canvas(auth: SessionData = Depends(require_auth)):
+    try:
+        with open("default_canvas.json", "r") as f:
+            canvas_data = json.load(f)
+        return canvas_data
+    except Exception as e:
+        return JSONResponse(
+            status_code=500,
+            content={"error": f"Failed to load default canvas: {str(e)}"}
+        )
+
 @canvas_router.post("")
-async def save_canvas(data: Dict[str, Any], auth: SessionData = Depends(require_auth)):
+async def save_canvas(data: Dict[str, Any], auth: SessionData = Depends(require_auth), request: Request = None):
     access_token = auth.token_data.get("access_token")
     decoded = jwt.decode(access_token, options={"verify_signature": False})
     user_id = decoded["sub"]
     success = await store_canvas_data(user_id, data)
     if not success:
         raise HTTPException(status_code=500, detail="Failed to save canvas data")
+    # PostHog analytics: capture canvas_saved event
+    try:
+        app_state = data.get("appState", {})
+        width = app_state.get("width")
+        height = app_state.get("height")
+        zoom = app_state.get("zoom", {}).get("value")
+        api_path = str(request.url.path) if request else None
+        full_url = None
+        if request:
+            full_url = str(request.base_url).rstrip("/") + str(request.url.path)
+        posthog.capture(
+            distinct_id=user_id,
+            event="canvas_saved",
+            properties={
+                "pad_width": width,
+                "pad_height": height,
+                "pad_zoom": zoom,
+                "$current_url": full_url,
+            }
+        )
+    except Exception as e:
+        print(f"Error capturing canvas_saved event: {str(e)}")
+        pass
     return {"status": "success"}
 
 @canvas_router.get("")

src/backend/routers/user.py

@@ -1,5 +1,6 @@
 import jwt
 from fastapi import APIRouter, Depends
+import posthog
 
 from dependencies import SessionData, require_auth
 
@@ -11,6 +12,19 @@ async def get_user_info(auth: SessionData = Depends(require_auth)):
     access_token = token_data.get("access_token")
 
     decoded = jwt.decode(access_token, options={"verify_signature": False})
+
+    # Identify user in PostHog (mirrors frontend identify)
+    posthog.identify(
+        distinct_id=decoded["sub"],
+        properties={
+            "email": decoded.get("email", ""),
+            "username": decoded.get("preferred_username", ""),
+            "name": decoded.get("name", ""),
+            "given_name": decoded.get("given_name", ""),
+            "family_name": decoded.get("family_name", ""),
+            "email_verified": decoded.get("email_verified", False)
+        }
+    )
 
     return {
         "id": decoded["sub"],  # Unique user ID
@@ -20,4 +34,4 @@ async def get_user_info(auth: SessionData = Depends(require_auth)):
         "given_name": decoded.get("given_name", ""),
         "family_name": decoded.get("family_name", ""),
         "email_verified": decoded.get("email_verified", False)
-    }
+    }