Allow Capacitor WebView origins in CORS/CSRF (#22) (#19)

## Summary
- Supports [chat_web_app#22](ai_ml_operations/chat_web_app#22)
- Always merge Capacitor WebView origins (`https://localhost`, `capacitor://localhost`, `http://localhost`) into `CORS_ALLOWED_ORIGINS` and `CSRF_TRUSTED_ORIGINS`
- Keep `CORS_ALLOW_CREDENTIALS = False` (JWT header-only; no cookie credentials)

## Test plan
- [x] `uv run python manage.py test chat_backend.tests.test_settings_cors`
- [ ] OPTIONS preflight from `https://localhost` / `capacitor://localhost` against prod/beta with `CORS_ORIGIN_ALLOW_ALL=false`
- [ ] Authenticated JWT GET/POST from Capacitor shell after FE #22 landsReviewed-on: #19

.env.prod.example

@@ -18,6 +18,7 @@ DJANGO_DEBUG=false
 DJANGO_SECRET_KEY=replace-with-a-long-random-secret
 DJANGO_ALLOWED_HOSTS=chatbackend.aimloperations.com
 # Optional override; when unset, https:// origins are derived from DJANGO_ALLOWED_HOSTS.
+# Capacitor WebView origins (https://localhost, capacitor://localhost) are always merged in code.
 # DJANGO_CSRF_TRUSTED_ORIGINS=https://chatbackend.aimloperations.com,https://chat.aimloperations.com
 CORS_ALLOWED_ORIGINS=https://chat.aimloperations.com
 CORS_ORIGIN_ALLOW_ALL=false

llm_be/chat_backend/tests/test_settings_cors.py

@@ -0,0 +1,61 @@
+from django.test import SimpleTestCase
+
+from llm_be.settings import (
+    CAPACITOR_WEBVIEW_ORIGINS,
+    build_csrf_trusted_origins,
+    with_capacitor_webview_origins,
+)
+
+
+class BuildCsrfTrustedOriginsTests(SimpleTestCase):
+    def test_derives_https_for_public_hosts(self):
+        origins = build_csrf_trusted_origins(
+            ["chat.aimloperations.com", "chatbackend.aimloperations.com"]
+        )
+        self.assertEqual(
+            origins,
+            [
+                "https://chat.aimloperations.com",
+                "https://chatbackend.aimloperations.com",
+            ],
+        )
+
+    def test_derives_http_for_localhost(self):
+        origins = build_csrf_trusted_origins(["localhost:8003", "127.0.0.1"])
+        self.assertEqual(
+            origins,
+            ["http://localhost:8003", "http://127.0.0.1"],
+        )
+
+    def test_explicit_list_wins(self):
+        origins = build_csrf_trusted_origins(
+            ["ignored.example"],
+            ["https://chat.aimloperations.com"],
+        )
+        self.assertEqual(origins, ["https://chat.aimloperations.com"])
+
+
+class CapacitorWebviewOriginTests(SimpleTestCase):
+    def test_appends_capacitor_origins(self):
+        merged = with_capacitor_webview_origins(["https://chat.aimloperations.com"])
+        self.assertEqual(merged[0], "https://chat.aimloperations.com")
+        for origin in CAPACITOR_WEBVIEW_ORIGINS:
+            self.assertIn(origin, merged)
+
+    def test_does_not_duplicate_existing(self):
+        seed = ["https://localhost", "https://chat.aimloperations.com"]
+        merged = with_capacitor_webview_origins(seed)
+        self.assertEqual(merged.count("https://localhost"), 1)
+        self.assertIn("capacitor://localhost", merged)
+
+    def test_settings_include_capacitor_origins(self):
+        from django.conf import settings
+
+        for origin in CAPACITOR_WEBVIEW_ORIGINS:
+            self.assertIn(origin, settings.CORS_ALLOWED_ORIGINS)
+            self.assertIn(origin, settings.CSRF_TRUSTED_ORIGINS)
+
+    def test_cors_credentials_disabled_for_jwt_only(self):
+        from django.conf import settings
+
+        self.assertFalse(settings.CORS_ALLOW_CREDENTIALS)

llm_be/llm_be/settings.py

@@ -74,11 +74,20 @@ def database_config() -> dict:
     }
 
 
+# Capacitor WebView origins (Android https://localhost, iOS capacitor://localhost).
+# Required so JWT API calls from native shells pass CORS/CSRF origin checks (#22).
+CAPACITOR_WEBVIEW_ORIGINS = (
+    "https://localhost",
+    "capacitor://localhost",
+    "http://localhost",
+)
+
+
 def build_csrf_trusted_origins(
     allowed_hosts: list[str], explicit: list[str] | None = None
 ) -> list[str]:
     if explicit:
-        return explicit
+        return list(explicit)
 
     local_hosts = {"localhost", "127.0.0.1", "0.0.0.0"}
     origins: list[str] = []
@@ -91,6 +100,17 @@ def build_csrf_trusted_origins(
     return origins
 
 
+def with_capacitor_webview_origins(origins: list[str]) -> list[str]:
+    """Append Capacitor WebView origins without duplicates (order preserved)."""
+    seen = set(origins)
+    merged = list(origins)
+    for origin in CAPACITOR_WEBVIEW_ORIGINS:
+        if origin not in seen:
+            merged.append(origin)
+            seen.add(origin)
+    return merged
+
+
 DJANGO_ENV = (env("DJANGO_ENV", "dev") or "dev").lower()
 
 SECRET_KEY = env(
@@ -106,16 +126,21 @@ allowed_hosts = env_list(
 )
 ALLOWED_HOSTS = allowed_hosts if allowed_hosts else ["*"]
 
-CSRF_TRUSTED_ORIGINS = build_csrf_trusted_origins(
+CSRF_TRUSTED_ORIGINS = with_capacitor_webview_origins(
+    build_csrf_trusted_origins(
         ALLOWED_HOSTS,
         env_list("DJANGO_CSRF_TRUSTED_ORIGINS"),
+    )
 )
 
+# JWT Authorization header only — no cookie credentials from the SPA/Capacitor shell.
 CORS_ALLOW_CREDENTIALS = False
 CORS_ORIGIN_ALLOW_ALL = env_bool("CORS_ORIGIN_ALLOW_ALL", True)
-CORS_ALLOWED_ORIGINS = env_list(
+CORS_ALLOWED_ORIGINS = with_capacitor_webview_origins(
+    env_list(
         "CORS_ALLOWED_ORIGINS",
         "http://localhost:3000,http://127.0.0.1:3000,https://chat.aimloperations.com",
+    )
 )
 
 # Ollama — GPU host on LAN for deployed envs; loopback for local Ollama.