feat: read-only live view at /view?key=<LIVEVIEW_KEY>

Implements issue #5. Off by default; set LIVEVIEW_KEY in .env to enable.
No JWT required — key-based auth via ?key= query param.
Returns 403 when disabled or key is wrong.
Read-only ReactFlow canvas (pan/zoom, no editing).
Standalone mode loads from localStorage without a key.
Includes 8 backend tests and 9 frontend tests.

backend/app/api/routes/liveview.py

@@ -0,0 +1,40 @@
+from typing import Any
+
+from fastapi import APIRouter, Depends, HTTPException, Query
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.config import settings
+from app.db.database import get_db
+from app.db.models import CanvasState, Edge, Node
+from app.schemas.canvas import CanvasStateResponse
+from app.schemas.edges import EdgeResponse
+from app.schemas.nodes import NodeResponse
+
+router = APIRouter()
+
+
+@router.get("", response_model=CanvasStateResponse)
+async def liveview_canvas(
+    key: str | None = Query(default=None),
+    db: AsyncSession = Depends(get_db),
+) -> CanvasStateResponse:
+    """Read-only public canvas endpoint.
+
+    Disabled by default — requires LIVEVIEW_KEY to be set in .env.
+    Always returns 403 when disabled, regardless of the key provided.
+    """
+    if not settings.liveview_key:
+        raise HTTPException(status_code=403, detail="Live view is disabled")
+    if not key or key != settings.liveview_key:
+        raise HTTPException(status_code=403, detail="Invalid live view key")
+
+    nodes = (await db.execute(select(Node))).scalars().all()
+    edges = (await db.execute(select(Edge))).scalars().all()
+    state = await db.get(CanvasState, 1)
+    viewport: dict[str, Any] = state.viewport if state else {"x": 0, "y": 0, "zoom": 1}
+    return CanvasStateResponse(
+        nodes=[NodeResponse.model_validate(n) for n in nodes],
+        edges=[EdgeResponse.model_validate(e) for e in edges],
+        viewport=viewport,
+    )

backend/app/core/config.py

@@ -30,6 +30,11 @@ class Settings(BaseSettings):
     # Leave empty to disable MCP service key auth.
     mcp_service_key: str = ""
 
+    # Live view — optional read-only public canvas endpoint.
+    # Set to a random secret string to enable /api/v1/liveview?key=<value>.
+    # Leave unset (or empty) to keep the feature disabled (default).
+    liveview_key: str | None = None
+
     def _override_path(self) -> Path:
         return Path(self.sqlite_path).parent / "scan_config.json"
 

backend/app/main.py

@@ -5,7 +5,7 @@ from typing import Any
 from fastapi import FastAPI
 from fastapi.middleware.cors import CORSMiddleware
 
-from app.api.routes import auth, canvas, edges, nodes, scan, status
+from app.api.routes import auth, canvas, edges, liveview, nodes, scan, status
 from app.core.config import settings
 from app.core.scheduler import start_scheduler, stop_scheduler
 from app.db.database import init_db
@@ -40,6 +40,7 @@ app.include_router(edges.router, prefix="/api/v1/edges", tags=["edges"])
 app.include_router(canvas.router, prefix="/api/v1/canvas", tags=["canvas"])
 app.include_router(scan.router, prefix="/api/v1/scan", tags=["scan"])
 app.include_router(status.router, prefix="/api/v1/status", tags=["status"])
+app.include_router(liveview.router, prefix="/api/v1/liveview", tags=["liveview"])
 
 
 @app.get("/api/v1/health")

backend/tests/test_liveview.py

@@ -0,0 +1,126 @@
+"""
+Tests for the /api/v1/liveview read-only canvas endpoint.
+
+The endpoint is:
+  - Disabled by default (LIVEVIEW_KEY not set) → 403
+  - Returns 403 for missing or wrong key even when enabled
+  - Returns canvas data for a valid key (no JWT required)
+"""
+
+import pytest
+from httpx import AsyncClient
+
+from app.core.config import settings
+
+
+@pytest.fixture(autouse=True)
+def reset_liveview_key():
+    """Restore liveview_key after each test so tests are isolated."""
+    original = settings.liveview_key
+    yield
+    settings.liveview_key = original
+
+
+# ── Disabled (no key configured) ─────────────────────────────────────────────
+
+@pytest.mark.asyncio
+async def test_liveview_disabled_by_default(client: AsyncClient):
+    settings.liveview_key = None
+    res = await client.get("/api/v1/liveview?key=anything")
+    assert res.status_code == 403
+    assert res.json()["detail"] == "Live view is disabled"
+
+
+@pytest.mark.asyncio
+async def test_liveview_disabled_when_key_empty(client: AsyncClient):
+    settings.liveview_key = ""
+    res = await client.get("/api/v1/liveview?key=anything")
+    assert res.status_code == 403
+    assert res.json()["detail"] == "Live view is disabled"
+
+
+# ── Enabled but wrong / missing key ──────────────────────────────────────────
+
+@pytest.mark.asyncio
+async def test_liveview_wrong_key(client: AsyncClient):
+    settings.liveview_key = "correct-secret"
+    res = await client.get("/api/v1/liveview?key=wrong-key")
+    assert res.status_code == 403
+    assert res.json()["detail"] == "Invalid live view key"
+
+
+@pytest.mark.asyncio
+async def test_liveview_missing_key_param(client: AsyncClient):
+    settings.liveview_key = "correct-secret"
+    res = await client.get("/api/v1/liveview")
+    assert res.status_code == 403
+    assert res.json()["detail"] == "Invalid live view key"
+
+
+# ── Valid key — no JWT needed ────────────────────────────────────────────────
+
+@pytest.mark.asyncio
+async def test_liveview_valid_key_returns_canvas(client: AsyncClient):
+    settings.liveview_key = "my-secret-key"
+    res = await client.get("/api/v1/liveview?key=my-secret-key")
+    assert res.status_code == 200
+    data = res.json()
+    assert "nodes" in data
+    assert "edges" in data
+    assert "viewport" in data
+    assert isinstance(data["nodes"], list)
+    assert isinstance(data["edges"], list)
+
+
+@pytest.mark.asyncio
+async def test_liveview_does_not_require_jwt(client: AsyncClient):
+    """Accessing without Authorization header must work when key is correct."""
+    settings.liveview_key = "open-sesame"
+    # client has no auth headers set here
+    res = await client.get("/api/v1/liveview?key=open-sesame")
+    assert res.status_code == 200
+
+
+@pytest.mark.asyncio
+async def test_liveview_returns_saved_canvas(client: AsyncClient, auth_headers):
+    """Canvas saved via POST /canvas/save appears in liveview response."""
+    settings.liveview_key = "test-key"
+    headers = await auth_headers()
+
+    # Save a canvas with one node
+    payload = {
+        "nodes": [{
+            "id": "lv-node-1",
+            "type": "server",
+            "label": "Live Node",
+            "status": "online",
+            "services": [],
+            "pos_x": 10,
+            "pos_y": 20,
+        }],
+        "edges": [],
+        "viewport": {"x": 0, "y": 0, "zoom": 1},
+    }
+    await client.post("/api/v1/canvas/save", json=payload, headers=headers)
+
+    # Liveview should return the same node
+    res = await client.get("/api/v1/liveview?key=test-key")
+    assert res.status_code == 200
+    nodes = res.json()["nodes"]
+    assert len(nodes) == 1
+    assert nodes[0]["id"] == "lv-node-1"
+    assert nodes[0]["label"] == "Live Node"
+
+
+# ── Re-disable after enabling ─────────────────────────────────────────────────
+
+@pytest.mark.asyncio
+async def test_liveview_disabled_after_key_cleared(client: AsyncClient):
+    settings.liveview_key = "was-enabled"
+    res = await client.get("/api/v1/liveview?key=was-enabled")
+    assert res.status_code == 200
+
+    settings.liveview_key = None
+    res = await client.get("/api/v1/liveview?key=was-enabled")
+    assert res.status_code == 403
+    assert res.json()["detail"] == "Live view is disabled"