| name | preview |
| description | Expose a dev server running in this session at a public preview URL. Use when the user asks to run, preview, or share the project's web app/dev server. |
brigade preview
This session runs inside brigade. Any HTTP server you start here can be reached
from the user's browser at a deterministic preview URL — no port forwarding needed.
How to expose a dev server
-
Start the server on any free port. If this session runs in Docker, bind to
0.0.0.0, not localhost (the proxy connects over the container network):
- vite:
vite --host 0.0.0.0; also allow the preview host via
server.allowedHosts: true (or list the host) in vite config;
- next:
next dev -H 0.0.0.0;
- python:
python3 -m http.server 8000 --bind 0.0.0.0.
-
Build the preview URL: take $BRIGADE_PREVIEW_URL_TEMPLATE and replace {port}
with the actual port. The template is already the full, correct URL for this
deployment (subdomain or single-host cookie form) — just substitute the port,
do not assemble it yourself. Examples:
http://abc-{port}.localhost:10000 → http://abc-3000.localhost:10000https://preview.example.com/?id=abc-{port} → https://preview.example.com/?id=abc-3000
-
Register the port so the link shows up in the brigade UI. This calls the
brigade.v1.AgentBridgeService/RegisterPreview ConnectRPC method — plain
POST with a JSON body, no client library needed:
curl -sf -X POST "$BRIGADE_API_URL/brigade.v1.AgentBridgeService/RegisterPreview" \
-H "Authorization: Bearer $BRIGADE_PREVIEW_TOKEN" \
-H "Content-Type: application/json" \
-d "{\"sessionId\": \"$BRIGADE_SESSION_ID\", \"port\": 3000, \"name\": \"vite\"}"
The response contains the final URL: {"url": "..."}.
-
Tell the user the preview URL.
Notes:
- The URL works as soon as the server is listening; registration only adds the
link to the UI.
- Re-register after restarting brigade if the link disappeared from the UI.
