fix(e2e): cloud auth via cookie, local port, Playwright WebSocket gotcha

E2E harness fixes to get all three modes (demo/cloud/local) passing:

- conftest.py: use ctx.add_cookies() for cloud auth instead of
  ctx.route() or set_extra_http_headers(). Playwright's route() only
  intercepts HTTP; set_extra_http_headers() explicitly excludes
  WebSocket handshakes. Streamlit reads st.context.headers from the
  WebSocket upgrade, so cookies are the only vehicle that reaches it
  without a reverse proxy.

- cloud_session.py: fall back to Cookie header when X-CF-Session is
  absent — supports direct access (E2E tests, dev without Caddy).
  In production Caddy sets X-CF-Session; in tests the cf_session cookie
  is set on the browser context and arrives in the Cookie header.

- modes/cloud.py: add /peregrine base URL path (STREAMLIT_SERVER_BASE_URL_PATH=peregrine)

- modes/local.py: correct port from 8502 → 8501 and add /peregrine path

All three modes now pass smoke + interaction tests clean.

app/cloud_session.py

@@ -151,7 +151,12 @@ def resolve_session(app: str = "peregrine") -> None:
     if st.session_state.get("user_id"):
         return
 
-    cookie_header = st.context.headers.get("x-cf-session", "")
+    # Primary: Caddy injects X-CF-Session header in production.
+    # Fallback: direct access (E2E tests, dev without Caddy) reads the cookie header.
+    cookie_header = (
+        st.context.headers.get("x-cf-session", "")
+        or st.context.headers.get("cookie", "")
+    )
     session_jwt = _extract_session_token(cookie_header)
     if not session_jwt:
         _render_auth_wall("Please sign in to access Peregrine.")

tests/e2e/conftest.py

@@ -93,11 +93,17 @@ def mode_contexts(active_modes, playwright) -> dict[str, BrowserContext]:
     for mode in active_modes:
         ctx = browser.new_context(viewport={"width": 1280, "height": 900})
         if mode.name == "cloud":
-            def _inject_jwt(route, request):
+            # Cookies are sent on WebSocket upgrade requests; set_extra_http_headers
+            # and ctx.route() are both HTTP-only and miss st.context.headers.
+            # cloud_session.py falls back to the Cookie header when X-CF-Session
+            # is absent (direct access without Caddy).
             jwt = _get_jwt()
-                headers = {**request.headers, "x-cf-session": f"cf_session={jwt}"}
-                route.continue_(headers=headers)
-            ctx.route(f"{mode.base_url}/**", _inject_jwt)
+            ctx.add_cookies([{
+                "name": "cf_session",
+                "value": jwt,
+                "domain": "localhost",
+                "path": "/",
+            }])
         else:
             mode.auth_setup(ctx)
         contexts[mode.name] = ctx

tests/e2e/modes/cloud.py

@@ -68,7 +68,7 @@ def _cloud_auth_setup(context: Any) -> None:
 
 CLOUD = ModeConfig(
     name="cloud",
-    base_url="http://localhost:8505",
+    base_url="http://localhost:8505/peregrine",
     auth_setup=_cloud_auth_setup,
     expected_failures=[],
     results_dir=Path("tests/e2e/results/cloud"),

tests/e2e/modes/local.py

@@ -9,7 +9,7 @@ _BASE_SETTINGS_TABS = [
 
 LOCAL = ModeConfig(
     name="local",
-    base_url="http://localhost:8502",
+    base_url="http://localhost:8501/peregrine",
     auth_setup=lambda ctx: None,
     expected_failures=[],
     results_dir=Path("tests/e2e/results/local"),