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/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"