feat(#17): web Bifrost-bind — server side (slice 3c, INV-008 lockstep complete)

Slice 3c of issue #17 — the web surface of the bind trigger, server side. Closes
the INV-008 lockstep (CLI + TUI + web all carry the bind now). Implements the
contract's "web bind split": the browser selects only the PLANE; the consumer key
and the Worldtree-visible host are SERVER-HELD config and never reach the browser.

- create_app gains bifrost_consumer_key + bifrost_visible_host (server-held,
  from env via the entrypoint: RATATOSKR_BIFROST_CONSUMER_KEY /
  RATATOSKR_PROVIDER_VISIBLE_HOST).
- _create_session_endpoint reads an optional `bifrost_plane` from the browser
  body, builds the BifrostBinding SERVER-SIDE via endpoint_for_plane(plane,
  visible_host), and calls create_session(bifrost=, consumer_key=). The 201
  response echoes bound-state {plane, endpoint, status: bound} for the UI
  indicator — never the key (INV-008/INV-009).
- Error routing: invalid plane / unconfigured server -> 400; BifrostHandshakeFailed
  -> 502 {bifrost_error}; BifrostConsumerKeyMissing (server misconfig) -> 400.

5 new web bind tests (server constructs binding + key-never-leaks + upstream
carries bifrost body + consumer-key bearer; unconfigured -> 400; invalid plane;
handshake 502; no-plane unbound regression). Full suite 470 green; added lines
ruff + mypy clean (pre-existing web-file backlog untouched).

Follow-on: the index.html plane selector (UI trigger) — the server capability is
complete and TDD'd; the browser-side dropdown is a thin separate change.

LIVE-SMOKE PROVEN (this session): the CLI bind drove a bound sindra session
against personal Worldtree :8081 -> handshake 200 -> the op-feed captured 2
recall searches correlated to the EXACT bound session_id (2c0c7482), with the
real #297/#298 union-recall scopes. Bind + observe proven end-to-end live.

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "ratatoskr"
-version = "0.17.11"
+version = "0.17.12"
 description = "Worldtree Conversation API debug TUI — multi-pane observability dashboard"
 readme = "README.md"
 requires-python = ">=3.12"

src/ratatoskr/web/entrypoint.py

@@ -59,6 +59,10 @@ def main(argv: list[str] | None = None) -> int:
         return 11
     server_url = os.environ.get("WORLDTREE_API_URL", "http://localhost:8000")
     end_user_id = os.environ.get("RATATOSKR_END_USER_ID")
+    # Issue #17 (web bind split): server-held Bifrost binding config. The browser
+    # selects the plane; the consumer key + visible host live server-side only.
+    bifrost_consumer_key = os.environ.get("RATATOSKR_BIFROST_CONSUMER_KEY")
+    bifrost_visible_host = os.environ.get("RATATOSKR_PROVIDER_VISIBLE_HOST")
 
     # INV-001: lazy import. Users without [web] extras get a clean hint
     # instead of a raw ImportError. Scoped narrowly to the OPTIONAL
@@ -93,7 +97,12 @@ def main(argv: list[str] | None = None) -> int:
             timeout=httpx.Timeout(connect=10.0, read=None, write=10.0, pool=10.0),
         )
 
-    app = create_app(client_factory, end_user_id=end_user_id)
+    app = create_app(
+        client_factory,
+        end_user_id=end_user_id,
+        bifrost_consumer_key=bifrost_consumer_key,
+        bifrost_visible_host=bifrost_visible_host,
+    )
 
     # Boot banner to stderr (so stdout stays clean for piping).
     version = _pkg_version("ratatoskr")

src/ratatoskr/web/server.py

@@ -27,9 +27,13 @@ from ratatoskr.sessions import (
     AgentNotAvailable,
     AgentNotFound,
     AuthScopeDenied,
+    BifrostBinding,
+    BifrostConsumerKeyMissing,
+    BifrostHandshakeFailed,
     PersonaNotConfigured,
     SessionApiFailed,
     create_session,
+    endpoint_for_plane,
     get_persona_state,
     list_agents,
 )
@@ -125,17 +129,65 @@ async def _create_session_endpoint(request: Request) -> JSONResponse:
         return JSONResponse({"error_code": "missing_agent_id"}, status_code=400)
     end_user_id = request.app.state.end_user_id
     client_factory = request.app.state.client_factory
+
+    # Issue #17 (web bind split): the browser may select a PLANE; the server holds
+    # the consumer key + visible host and constructs the binding. The consumer key
+    # NEVER reaches the browser (INV-008/INV-009).
+    bifrost: BifrostBinding | None = None
+    bifrost_plane = body.get("bifrost_plane") if isinstance(body, dict) else None
+    consumer_key = request.app.state.bifrost_consumer_key
+    visible_host = request.app.state.bifrost_visible_host
+    if bifrost_plane:
+        if bifrost_plane not in ("memory", "affect"):
+            return JSONResponse(
+                {"error_code": "invalid_bifrost_plane"}, status_code=400
+            )
+        if not (consumer_key and visible_host):
+            return JSONResponse(
+                {"error_code": "bifrost_not_configured"}, status_code=400
+            )
+        bifrost = BifrostBinding(
+            endpoint_url=endpoint_for_plane(bifrost_plane, visible_host)
+        )
+
     try:
         async with client_factory() as client:
-            info = await create_session(client, agent_id, end_user_id=end_user_id)
+            info = await create_session(
+                client,
+                agent_id,
+                end_user_id=end_user_id,
+                bifrost=bifrost,
+                consumer_key=consumer_key if bifrost else None,
+            )
     except AgentNotFound:
         return JSONResponse({"error_code": "agent_not_found"}, status_code=404)
+    except BifrostConsumerKeyMissing:
+        # Server misconfiguration: a plane was requested but no consumer key.
+        return JSONResponse(
+            {"error_code": "bifrost_not_configured"}, status_code=400
+        )
+    except BifrostHandshakeFailed as exc:
+        return JSONResponse(
+            {
+                "error_code": "bifrost_handshake_failed",
+                "bifrost_error": exc.bifrost_error,
+            },
+            status_code=502,
+        )
     except SessionApiFailed as exc:
         return JSONResponse(
             {"error_code": "session_api_failed", "status": exc.status},
             status_code=exc.status,
         )
-    return JSONResponse(_as_dict(info), status_code=201)
+    payload = _as_dict(info)
+    if bifrost is not None:
+        # Bound-state for the UI indicator — plane + endpoint only, never the key.
+        payload["bifrost"] = {
+            "plane": bifrost_plane,
+            "endpoint": bifrost.endpoint_url,
+            "status": "bound",
+        }
+    return JSONResponse(payload, status_code=201)
 
 
 @dataclass
@@ -345,6 +397,8 @@ def create_app(
     client_factory: Callable[[], httpx.AsyncClient],
     *,
     end_user_id: str | None = None,
+    bifrost_consumer_key: str | None = None,
+    bifrost_visible_host: str | None = None,
 ) -> Starlette:
     """Construct the Starlette app — wire routes + state per FN create_app.
 
@@ -411,6 +465,11 @@ def create_app(
     app = Starlette(routes=routes, lifespan=lifespan)
     app.state.client_factory = client_factory
     app.state.end_user_id = end_user_id
+    # Issue #17 (web bind split): the consumer key + Worldtree-visible provider
+    # host are SERVER-HELD config (env), never sent from the browser. The browser
+    # selects only the PLANE; the server constructs the bound session (INV-008).
+    app.state.bifrost_consumer_key = bifrost_consumer_key
+    app.state.bifrost_visible_host = bifrost_visible_host
     # INV-002: turn registry is in-process memory, keyed (session_id, turn_id)
     app.state.turn_registry = {}
     return app

tests/test_web_server.py

@@ -792,3 +792,113 @@ class TestDisconnectCancel:
             await asyncio.sleep(0.02)
         gate.set()
         assert cancel_route.called, "browser disconnect must cancel the UPSTREAM turn (42)"
+
+
+class TestWebBifrostBind:
+    """Issue #17 slice 3c — web bind split: the browser selects the PLANE; the
+    consumer key + visible host are SERVER-HELD and never reach the browser
+    (INV-008/INV-009)."""
+
+    @respx.mock
+    def test_bound_create_server_constructs_binding_key_never_leaks(self) -> None:
+        """tracer: a plane from the browser → the server builds the binding with
+        its OWN consumer key + host, sends the bifrost body + consumer-key bearer
+        upstream, and returns bound-state WITHOUT the key."""
+        import json as _json
+
+        from ratatoskr.web.server import create_app
+
+        route = respx.post("https://w.example/sessions").mock(
+            return_value=httpx.Response(201, json=_CREATE_OK)
+        )
+        app = create_app(
+            _mock_client_factory(),
+            bifrost_consumer_key="server-ck",
+            bifrost_visible_host="10.100.10.50",
+        )
+        resp = TestClient(app).post(
+            "/api/sessions", json={"agent_id": "ratatoskr:sindra", "bifrost_plane": "memory"}
+        )
+        assert resp.status_code == 201
+        # bound-state echoed for the UI indicator — plane + endpoint, NO key
+        assert resp.json()["bifrost"] == {
+            "plane": "memory",
+            "endpoint": "http://10.100.10.50:8391",
+            "status": "bound",
+        }
+        assert "server-ck" not in resp.text  # the key never reaches the browser
+        # upstream got the bifrost body + the consumer-key bearer override
+        upstream = route.calls[0].request
+        body = _json.loads(upstream.content)
+        assert body["bifrost"] == {
+            "endpoint_url": "http://10.100.10.50:8391", "scope": None
+        }
+        assert upstream.headers["Authorization"] == "Bearer server-ck"
+
+    @respx.mock
+    def test_plane_without_server_config_is_400(self) -> None:
+        """A plane requested but no server-held key/host → bifrost_not_configured."""
+        from ratatoskr.web.server import create_app
+
+        app = create_app(_mock_client_factory())  # no bifrost config
+        resp = TestClient(app).post(
+            "/api/sessions", json={"agent_id": "a", "bifrost_plane": "memory"}
+        )
+        assert resp.status_code == 400
+        assert resp.json()["error_code"] == "bifrost_not_configured"
+
+    def test_invalid_plane_is_400(self) -> None:
+        from ratatoskr.web.server import create_app
+
+        app = create_app(
+            _mock_client_factory(),
+            bifrost_consumer_key="ck",
+            bifrost_visible_host="h",
+        )
+        resp = TestClient(app).post(
+            "/api/sessions", json={"agent_id": "a", "bifrost_plane": "persona"}
+        )
+        assert resp.status_code == 400
+        assert resp.json()["error_code"] == "invalid_bifrost_plane"
+
+    @respx.mock
+    def test_handshake_failure_is_502(self) -> None:
+        from ratatoskr.web.server import create_app
+
+        respx.post("https://w.example/sessions").mock(
+            return_value=httpx.Response(
+                502,
+                json={
+                    "error_code": "bifrost_handshake_failed",
+                    "detail": {"bifrost_error": "bifrost.auth_rejected"},
+                },
+            )
+        )
+        app = create_app(
+            _mock_client_factory(),
+            bifrost_consumer_key="ck",
+            bifrost_visible_host="h",
+        )
+        resp = TestClient(app).post(
+            "/api/sessions", json={"agent_id": "a", "bifrost_plane": "memory"}
+        )
+        assert resp.status_code == 502
+        assert resp.json()["error_code"] == "bifrost_handshake_failed"
+        assert resp.json()["bifrost_error"] == "bifrost.auth_rejected"
+
+    @respx.mock
+    def test_no_plane_is_unbound_no_bifrost_in_response(self) -> None:
+        """regression: no bifrost_plane → pre-#17 unbound create, no bifrost key."""
+        from ratatoskr.web.server import create_app
+
+        respx.post("https://w.example/sessions").mock(
+            return_value=httpx.Response(201, json=_CREATE_OK)
+        )
+        app = create_app(
+            _mock_client_factory(),
+            bifrost_consumer_key="ck",
+            bifrost_visible_host="h",
+        )
+        resp = TestClient(app).post("/api/sessions", json={"agent_id": "mimir"})
+        assert resp.status_code == 201
+        assert "bifrost" not in resp.json()

uv.lock

@@ -1052,7 +1052,7 @@ wheels = [
 
 [[package]]
 name = "ratatoskr"
-version = "0.17.11"
+version = "0.17.12"
 source = { editable = "." }
 dependencies = [
     { name = "httpx" },