Show the OIDC profile picture with an identicon fallback

GET /api/me now carries the profile picture URL when the provider
supplies an absolute http(s) one; the SPA shows it in the lobby navbar
and draws a deterministic identicon from the sub otherwise, falling back
to the identicon when the image fails to load.

The identicon is a 5x5 mirrored grid seeded by an inline FNV-1a hash so
it stays stable across Rust versions and is unit-testable on the host.
The dev mock IdP hands alice and bob a picture claim.

server/dev/mockoauth/config.json

@@ -11,7 +11,8 @@
           "claims": {
             "sub": "alice",
             "preferred_username": "alice",
-            "name": "Alice"
+            "name": "Alice",
+            "picture": "https://i.pravatar.cc/128?u=alice"
           }
         },
         {
@@ -20,7 +21,8 @@
           "claims": {
             "sub": "bob",
             "preferred_username": "bob",
-            "name": "Bob"
+            "name": "Bob",
+            "picture": "https://i.pravatar.cc/128?u=bob"
           }
         },
         {

server/packages/tavolo-platform/src/tavolo/platform/auth.py

@@ -60,6 +60,19 @@ def display_name(user: OIDCUser) -> str:
     return user.sub
 
 
+def picture(user: OIDCUser) -> Optional[str]:
+    """The user's avatar URL, when the provider supplies a usable one.
+
+    Only absolute ``http(s)`` URLs are exported: the claim ends up in an
+    ``<img src>`` in the SPA, where relative or script-ish schemes have no
+    business.
+    """
+    value = user.picture
+    if isinstance(value, str) and value.startswith(("http://", "https://")):
+        return value
+    return None
+
+
 def current_user(oidc: OIDCProviders, ctx: HttpContext) -> Optional[OIDCUser]:
     """Return the authenticated user of an HTTP request, if any.
 

server/packages/tavolo-platform/src/tavolo/platform/openapi.py

@@ -126,8 +126,9 @@ ME_SCHEMA = _object(
     {
         "sub": {"type": "string"},
         "name": {"type": "string"},
+        "picture": _nullable({"type": "string"}),
     },
-    ("sub", "name"),
+    ("sub", "name", "picture"),
 )
 
 AUTH_PROVIDER_SCHEMA = _object(

server/packages/tavolo-platform/src/tavolo/platform/routes/me.py

@@ -6,7 +6,7 @@ from typing import TYPE_CHECKING
 from kaya.core import HttpContext, KayaApp
 from kaya.openapi import operation, schema_ref
 
-from ..auth import current_user, display_name, require_auth
+from ..auth import current_user, display_name, picture, require_auth
 from ..http import send_json
 from ..openapi import error_response, json_response
 
@@ -18,7 +18,9 @@ def register(app: KayaApp, platform: "Platform") -> None:
     @app.GET("/api/me")
     @operation(summary="Current user",
                description="Returns the authenticated user's identity from the "
-                           "session; 401 when not logged in.",
+                           "session, including the profile picture URL when "
+                           "the provider supplies one; 401 when not logged "
+                           "in.",
                tags=["auth"],
                responses={
                    200: json_response("The current user", schema_ref("Me")),
@@ -28,4 +30,12 @@ def register(app: KayaApp, platform: "Platform") -> None:
     async def me(ctx: HttpContext) -> None:
         user = current_user(platform.oidc, ctx)
         assert user is not None  # enforced by @require_auth
-        await send_json(ctx, 200, {"sub": user.sub, "name": display_name(user)})
+        await send_json(
+            ctx,
+            200,
+            {
+                "sub": user.sub,
+                "name": display_name(user),
+                "picture": picture(user),
+            },
+        )

server/packages/tavolo-platform/tests/test_auth.py

@@ -19,6 +19,7 @@ from tavolo.platform.auth import (
     current_user,
     display_name,
     get_ws_user,
+    picture,
     require_auth,
     session_user,
 )
@@ -121,6 +122,23 @@ class DisplayNameTest(unittest.TestCase):
         self.assertEqual("alice", display_name(user))
 
 
+class PictureTest(unittest.TestCase):
+    """Only absolute http(s) picture claims are exported to the SPA."""
+
+    def test_uses_an_absolute_http_url(self) -> None:
+        user = OIDCUser({"sub": "alice", "picture": "https://cdn.example.com/a.png"})
+        self.assertEqual("https://cdn.example.com/a.png", picture(user))
+
+    def test_rejects_relative_and_script_schemes(self) -> None:
+        for value in ("/relative.png", "javascript:alert(1)", "data:image/png;base64,x"):
+            with self.subTest(picture=value):
+                user = OIDCUser({"sub": "alice", "picture": value})
+                self.assertIsNone(picture(user))
+
+    def test_missing_claim_is_none(self) -> None:
+        self.assertIsNone(picture(OIDCUser({"sub": "alice"})))
+
+
 class CurrentUserTest(unittest.TestCase):
     def test_anonymous_session_has_no_user(self) -> None:
         self.assertIsNone(current_user(_providers("default"), _ctx({})))

server/packages/tavolo-platform/tests/test_routes.py

@@ -310,7 +310,10 @@ class MeRouteTest(unittest.TestCase):
             with oidc_user(platform.oidc, "alice"):
                 response = await client.get("/api/me")
             self.assertEqual(200, response.status_code)
-            self.assertEqual({"sub": "alice", "name": "alice"}, response.json())
+            self.assertEqual(
+                {"sub": "alice", "name": "alice", "picture": None},
+                response.json(),
+            )
 
     @async_test
     async def test_me_unauthenticated(self) -> None:

server/tests/helpers/oidc.py

@@ -24,25 +24,34 @@ _PROVIDER = next(iter(oidc.providers))
 
 
 def make_user(
-    sub: str, name: Optional[str] = None, email: Optional[str] = None
+    sub: str,
+    name: Optional[str] = None,
+    email: Optional[str] = None,
+    picture: Optional[str] = None,
 ) -> OIDCUser:
     claims = {"sub": sub, "preferred_username": name or sub}
     if email:
         claims["email"] = email
+    if picture:
+        claims["picture"] = picture
     return OIDCUser(claims)
 
 
 @contextlib.contextmanager
 def oidc_user(
-    sub: str, name: Optional[str] = None, email: Optional[str] = None
+    sub: str,
+    name: Optional[str] = None,
+    email: Optional[str] = None,
+    picture: Optional[str] = None,
 ) -> Iterator[OIDCUser]:
     """Context manager: make ``oidc.get_users`` return this user.
 
     ``email`` is optional so tests can simulate an IdP that still returns
     the claim: the app requests only the ``openid`` and ``profile`` scopes
-    and ignores email where present.
+    and ignores email where present. ``picture`` simulates the profile
+    scope's avatar claim.
     """
-    user = make_user(sub, name, email)
+    user = make_user(sub, name, email, picture)
     patcher = _mock.patch.object(oidc, "get_users", return_value={_PROVIDER: user})
     patcher.start()
     try:

server/tests/test_routes_me.py

@@ -22,8 +22,33 @@ class MeRouteTest(unittest.TestCase):
             with oidc_user("alice", email="alice@example.com"):
                 response = await client.get("/api/me")
             self.assertEqual(200, response.status_code)
-            # The email claim the IdP returns is neither stored nor exposed.
-            self.assertEqual({"sub": "alice", "name": "alice"}, response.json())
+            # The email claim the IdP returns is neither stored nor exposed;
+            # no picture claim in this request.
+            self.assertEqual(
+                {"sub": "alice", "name": "alice", "picture": None},
+                response.json(),
+            )
+
+    @async_test
+    async def test_me_includes_the_profile_picture(self) -> None:
+        transport = ASGITransport(app=app)
+        async with AsyncClient(transport=transport, base_url="http://127.0.0.1") as client:
+            with oidc_user("alice", picture="https://cdn.example.com/alice.png"):
+                response = await client.get("/api/me")
+        self.assertEqual(200, response.status_code)
+        self.assertEqual(
+            "https://cdn.example.com/alice.png",
+            response.json()["picture"],
+        )
+
+    @async_test
+    async def test_me_rejects_non_http_picture_claims(self) -> None:
+        transport = ASGITransport(app=app)
+        async with AsyncClient(transport=transport, base_url="http://127.0.0.1") as client:
+            with oidc_user("alice", picture="javascript:alert(1)"):
+                response = await client.get("/api/me")
+        self.assertEqual(200, response.status_code)
+        self.assertIsNone(response.json()["picture"])
 
     @async_test
     async def test_me_unauthenticated(self) -> None: