Replace Statsig with GrowthBook for experimentation

app/backend.dev.env

@@ -87,8 +87,8 @@ ACTIVENESS_PROBES_ENABLED=1
 # Experimentation (feature flags)
 EXPERIMENTATION_ENABLED=0
 EXPERIMENTATION_PASS_ALL_GATES=1
-STATSIG_SERVER_SECRET_KEY=secret-...
-STATSIG_ENVIRONMENT=development
+GROWTHBOOK_API_HOST=https://gbapi.couchershq.org
+GROWTHBOOK_CLIENT_KEY=sdk-cGmljeXu1BCzHffE
 
 # Moderation auto-approval deadline in seconds (0 to disable)
 MODERATION_AUTO_APPROVE_DEADLINE_SECONDS=10

app/backend/pyproject.toml

@@ -41,7 +41,7 @@ dependencies = [
     "stripe>=13.1.0",
     "ua-parser>=1.0.1",
     "user-agents>=2.2.0",
-    "statsig-python-core>=0.8.0",
+    "growthbook>=1.2.0",
 ]
 
 [project.scripts]
@@ -136,7 +136,7 @@ module = ["couchers.migrations.versions.*"]
 ignore_errors = true
 
 [[tool.mypy.overrides]]
-module = ["http_ece", "py_vapid", "luhn", "sqlalchemy_utils.*", "statsig_python_core", "user_agents"]
+module = ["http_ece", "py_vapid", "luhn", "sqlalchemy_utils.*", "growthbook", "user_agents"]
 # These libraries don't have type stubs or py.typed markers
 ignore_missing_imports = true
 

app/backend/src/app.py

@@ -96,8 +96,6 @@ def main() -> None:
     setup_tracing()
 
     # Initialize the experimentation framework for feature flags in the main process.
-    # IMPORTANT: This MUST be called AFTER worker processes are spawned (above).
-    # The underlying SDK uses internal threading that doesn't survive fork().
     # Worker processes initialize their own instance in _run_forever().
     setup_experimentation()
 

app/backend/src/couchers/config.py

@@ -115,13 +115,13 @@
     ("RECAPTHCA_SITE_KEY", str),
     # Whether we're in test
     ("IN_TEST", bool, "0"),
-    # Experimentation (feature flags via Statsig)
+    # Experimentation (feature flags via GrowthBook)
     ("EXPERIMENTATION_ENABLED", bool, "0"),
     # When enabled, all feature gates return True (useful for development/testing)
     ("EXPERIMENTATION_PASS_ALL_GATES", bool, "0"),
-    # Statsig SDK configuration
-    ("STATSIG_SERVER_SECRET_KEY", str, ""),
-    ("STATSIG_ENVIRONMENT", str, "development"),
+    # GrowthBook SDK configuration
+    ("GROWTHBOOK_API_HOST", str, "https://cdn.growthbook.io"),
+    ("GROWTHBOOK_CLIENT_KEY", str, ""),
     # Moderation auto-approval deadline in seconds (0 to disable auto-approval)
     ("MODERATION_AUTO_APPROVE_DEADLINE_SECONDS", int),
     # User ID of the bot user for automated moderation actions
@@ -171,8 +171,8 @@ def check_config(cfg: dict[str, Any]) -> None:
             raise Exception("MyPostcard API credentials not configured but postal verification enabled")
 
     if cfg["EXPERIMENTATION_ENABLED"]:
-        if not cfg["STATSIG_SERVER_SECRET_KEY"]:
-            raise Exception("No Statsig server secret key but experimentation enabled")
+        if not cfg["GROWTHBOOK_CLIENT_KEY"]:
+            raise Exception("No GrowthBook client key but experimentation enabled")
 
 
 def make_config() -> dict[str, Any]:

app/backend/src/couchers/context.py

@@ -1,9 +1,12 @@
-from typing import NoReturn, cast
+from typing import TYPE_CHECKING, NoReturn, cast
 
 import grpc
 
 from couchers.i18n import LocalizationContext
 
+if TYPE_CHECKING:
+    from growthbook import GrowthBook
+
 
 class NonInteractiveContextException(Exception):
     """If this exception is raised, it is a programming error"""
@@ -79,6 +82,7 @@ def __init__(
         self.__is_interactive = is_interactive
         self.__logged_in = self._user_id is not None
         self.__cookies: list[str] = []
+        self._growthbook: GrowthBook | None = None
 
         if self.__is_interactive:
             if not self._grpc_context: