Deploy the agent behind the Gateway
Mount the conversational operator agent behind the Gateway as a chat API, and drive a session through an approval-gated write
Overview
@tetherto/mdk-app-agent mounts @tetherto/mdk-agent behind the Gateway as a chat API.
Enable the app for session, message, and approval routes: every write the agent proposes pauses for an operator's
decision. The agent itself still reaches fleet data the way any AI agent does, over an MCP server reachable at agent.mcp.url
— the standalone @tetherto/mdk-mcp process; this app gives a human operator a chat surface to talk to it through.
This is one of two ways to run the agent. If you've already run it standalone, it's the same agent with HTTP on it, not a second product: the same provider, the same MCP client, the same approval gate, just reached over sessions instead of a REPL.
Prerequisites
- The Gateway is running
- A model is served on this machine, or reachable on another, because the app dials the provider rather than starting one
- An MCP tool server is reachable, so the agent has fleet tools to call
The Gateway never starts a model. config.agent.provider is a URL it dials, so a first session against a baseURL with nothing
behind it fails with ERR_AGENT_UNAVAILABLE. Serving a model locally with QVAC covers the install, the first-run
download, and the flags a lazily loaded model needs.
Mount the app
Either:
A Select it during onboarding
Run mdk onboard and select mdk-app-agent from its app catalog.
mdk onboard's wizard supports creating a compliant mdk.yaml from scratch, interactively.
It installs @tetherto/mdk-app-agent by package name and writes its spec.apps entry with mount: /.
The catalog entry installs the package by name from npm, where it is not published, so that install fails. Install it from
its public repository instead, with mdk add app github:tetherto/mdk-app-agent, which writes the same
spec.apps entry, mount: / included. That entry carries serviceAccount: app:agent and a permissionsDigest, and the
install also writes a credential under .mdk/credentials/apps/. The dependency it records in package.json is the
github: specifier, carrying no version or ref, so the commit is pinned by your lockfile rather than by the manifest.
Commit the lockfile: without one, a later install resolves whatever that repository's default branch points at.
B Add it to an existing mdk.yaml
Already have one from a previous onboarding run? Add the app under spec.apps by hand, with mount: / and the model
provider, the MCP url, and the approval timeout under agent. The app resolves from
node_modules/@tetherto/mdk-app-agent. For example, a standalone gateway carrying just this app, reaching across
to the MVP site example's MCP tool server:
apiVersion: mdk/v1
kind: Stack
metadata:
name: agent-gateway
spec:
workers: []
gateway:
port: 3847
apps:
- name: agent
package: "@tetherto/mdk-app-agent"
mount: /
config:
agent:
provider: { kind: qvac, model: qwen3-4b, baseURL: http://127.0.0.1:11500/v1 }
mcp: { url: http://127.0.0.1:3101/mcp }
approvalTimeoutMs: 120000Keep mount: /. The agent UI calls /agent/sessions… at the Gateway root; without it the routes live
under /apps/agent/agent/sessions… and the UI gets 404.
1.2 Run it
Once the mdk.yaml names the app, either way, write the access policy before the first run:
mdk rbac initmdk run refuses a stack whose spec.rbac binds nobody, because the Kernel would boot with nobody able to administer it.
mdk rbac init writes the starter policy: an admin role, the CLI bound to it, and the Gateway and MCP server bound to
read policy. Step 4 of the security blueprint covers what it writes and how to change it.
Then run mdk run. It starts the app in its own runtime process and the Gateway forwards the agent routes to it.
A stack built for just this app declares no Workers, so mdk run boots a Kernel it never actually uses
(it only proxies chat to the MVP site's separate MCP server) alongside the app and the Gateway.
The agent routes are auth: true, so each one is checked against spec.rbac and needs an access token. A call without one
answers 401 ERR_AUTH_UNAUTHORIZED. Create the first operator with mdk user add <name> --admin while
the stack is running, then sign in at POST /auth/login and send the accessToken it returns as
Authorization: Bearer <token> (Gateway security model).
A missing config.agent block
answers 503 ERR_AGENT_UNAVAILABLE instead of failing to load.
This app requests no Kernel access of its own, so mdk run warns that app agent has no binding in spec.rbac on every
start, even once mdk rbac init has run and reports the grant already in place. There is nothing to bind for an app with
no permissions, and the warning does not stop the app serving. Running mdk rbac init again changes nothing.
Create a session and send a message
Use the port your mdk.yaml gave the gateway: 3847 in the example above. Note that
the MVP site's own gateway (3000) never carries the agent app; this is a separate gateway, reaching
across to the MVP site's MCP tool server on 3101.
Sign in first. The access token comes back in the response body; every call below carries it.
TOKEN=$(curl -s -X POST http://localhost:<port>/auth/login \
-H 'Content-Type: application/json' \
-d '{"username":"<name>","password":"<password>"}' | jq -r .accessToken)
curl -X POST http://localhost:<port>/agent/sessions \
-H "Authorization: Bearer $TOKEN"
# {"sessionId":"..."}
curl -N -X POST http://localhost:<port>/agent/sessions/<id>/messages \
-H "Authorization: Bearer $TOKEN" \
-H 'Content-Type: application/json' \
-d '{"text":"how many miners are on the site?"}'The response streams as text/event-stream. A read-only question ends in tool_call, tool_result, token, and done
events, each stamped with the turn's turnId and a monotonic seq.
Approve a write
A write action pauses the turn instead of running it:
event: pending_approval
data: {"type":"pending_approval","name":"act_device","args":{"ref":"whatsminer-0","action":"reboot"},"approvalId":"..."}Decide it from the paused stream's approvalId:
curl -X POST http://localhost:<port>/agent/sessions/<id>/approvals/<approvalId> \
-H "Authorization: Bearer $TOKEN" \
-H 'Content-Type: application/json' \
-d '{"approved":true}'Approving resumes the same stream: the tool runs for real, and the turn continues to its token and done events. Rejecting,
or letting the approval window expire, resolves to false, and the write never runs.
Troubleshooting
- Sessions and messages work, but the agent never calls a tool.
agent.mcp(or itsurl) is missing from the config — how to fix it is in the app's troubleshooting entry - Every agent route answers
401. No access token on the call, or an expired one. Sign in again atPOST /auth/loginand resend withAuthorization: Bearer <token> - The agent routes answer
404. The app entry has nomount: /, so its routes are served under/apps/<name>. Addmount: /to itsspec.appsentry - Every other failure (
503,404,409,400) maps to a specific cause and fix in the app's error reference npm cifails to resolve a stack that mounts only this app.@tetherto/mdk-app-agentdeclares@tetherto/mdk-agentas a required dependency, not an optional peer, so the agent package must be installed alongside it fornpm cito resolve.
Next steps
- Read the agent app's route reference: session, message, and approval routes, plus the manifest's
setupfields - Get the agent app: its public repository, and why the onboarding catalog cannot install it yet
- Understand the underlying agent: the model and its fleet tools
- Submit and approve write actions from a React app, for the UI-driven shape of this same approval gate