Topology, root cause and blast radius

The floor of the city shows who talks to whom as lines of light. Pulses flow from the user to the used: a web server's link to its database flows toward the database.

Where links come from

Links are never guessed from names or districts. There are three sources:

Kind	Source	Looks like
declared	dependsOn: [ids] on a server or resource (you wrote it)	faint, slow
observed	a TCP connection really seen on a server, to another building's address and port	brighter, bows aside
balances	a target an AWS load balancer reports	bright, bows the other way
probes	dependsOn on an HTTP/TCP probe: what it really hits	faint

Observed connections come from service discovery. They fade out after four discovery rounds without the connection. Links touching the focused building turn cyan.

hosts.yaml

hosts:
  - id: lekhix-api
    address: 10.0.1.12
    user: ops
    dependsOn: [orders-db, rate-limit-cache]

Blast radius

Every building's panel shows Blast radius: N depend on it: everything that uses it, directly or through others, nearest first. Before you restart a database, you see what goes down with it.

Root cause

When two or more things fail at once, a banner at the top names the likely root cause: a failing building whose own dependencies are healthy, with how many other failures it explains. The Doctor panel lists every root cause with a Diagnose button.

Here orders-db explains the four failures upstream of it: fix it first.

For AI agents

incident_report returns the same analysis in one call (root causes, what each explains, what is still up but at risk), and get_topology the links and blast radius of any building. See MCP tools.