feat: add active_view to StatePatch model and patch_state handler

- Add optional active_view field to StatePatch Pydantic model
- Add active_view handling in patch_state to persist the field
- Add test_patch_state_sets_active_view: verifies PATCH persists active_view
- Add test_patch_state_active_view_defaults_to_all: verifies GET returns 'all' by default

Closes task-1: Add active_view to StatePatch Model

muxplex/main.py

@@ -423,6 +423,7 @@ class StatePatch(BaseModel):
     session_order: list[str] | None = None
     active_session: str | None = None
     active_remote_id: str | None = None
+    active_view: str | None = None
 
 
 class HeartbeatPayload(BaseModel):
@@ -495,6 +496,8 @@ async def patch_state(patch: StatePatch) -> dict:
             state["active_session"] = patch.active_session
         if "active_remote_id" in changed:
             state["active_remote_id"] = patch.active_remote_id
+        if "active_view" in changed:
+            state["active_view"] = patch.active_view
         save_state(state)
         return state
 

muxplex/tests/test_api.py

@@ -227,6 +227,39 @@ def test_patch_state_ignores_unknown_fields(client):
     assert data["session_order"] == ["a", "b"]
 
 
+def test_patch_state_sets_active_view(client):
+    """PATCH /api/state with active_view persists the value.
+
+    Verifies response contains active_view and subsequent GET returns the value.
+    """
+    from muxplex.state import load_state
+
+    # PATCH with a specific active_view value
+    response = client.patch("/api/state", json={"active_view": "my-view"})
+    assert response.status_code == 200
+    data = response.json()
+    assert data["active_view"] == "my-view"
+
+    # Verify the value persists via GET
+    get_response = client.get("/api/state")
+    assert get_response.status_code == 200
+    get_data = get_response.json()
+    assert get_data["active_view"] == "my-view"
+
+    # Also verify it was persisted to disk
+    persisted = load_state()
+    assert persisted["active_view"] == "my-view"
+
+
+def test_patch_state_active_view_defaults_to_all(client):
+    """GET /api/state returns active_view='all' by default."""
+    response = client.get("/api/state")
+    assert response.status_code == 200
+    data = response.json()
+    assert "active_view" in data
+    assert data["active_view"] == "all"
+
+
 # ---------------------------------------------------------------------------
 # GET /api/sessions
 # ---------------------------------------------------------------------------