sectr.server

sectr.server mounts an AgentApp as the runner invoke contract (schema/invocation.schema.json): POST /invocations with {session_id, invocation_id, route, transcript, reason}, answered by an SSE stream of runner events. You almost never touch this module — sectr dev and the production sidecar do:

• sectr dev spawns uv run python -m sectr.server <entry> — the module form of main() below.
• The production sidecar imports your app and calls run(app) directly.

create_asgi(app)

Builds the FastAPI app implementing the contract:

1. structurally validates the request body (missing/wrongly-typed fields → 422);
2. dispatches by route to the registered handler;
3. constructs the SessionContext (transcript envelopes + the polymorphic reason);
4. streams the handler through sectr.drive as SSE — data: = one runner event JSON per frame.

sectr.drive enforces finality: exactly one terminal event — NO_MORE_ACTIONS appended on generator exhaustion (turn over) or ToolApprovalRequired last (turn suspended). Handlers can’t end a turn wrongly; the adapter makes the contract impossible to violate by accident.

run(app) / python -m sectr.server <entry>

run(app) serves on 127.0.0.1:$SECTR_PORT (default 8080) — the sidecar sets the port. The CLI form resolves module:attribute, imports it, and serves — that’s the entry sectr dev uses for the subprocess runner.

Why localhost-only

The runner is a pure function: (transcript, reason) → event stream. It holds no platform credentials and no journal access — the only caller is the sidecar, on localhost, with the invocation’s events forwarded over the sidecar’s own connection. That’s the trust boundary: user-code compromise can’t touch other sessions or the platform.