SerenSinew

The connective tissue of the Seren stack.

If SerenMeninges is the membrane - the UI shell, auth, config, credentials every service wears - then Sinew is the tendon: the cross-cutting runtime plumbing every Seren web service repeats. One copy, so a fix lands everywhere at once.

What's in it (today)

Request logging. Drop-in middleware that logs every HTTP request as <client> <METHOD> <path> -> <status> (<ms>ms) [rid=<id>] - INFO for 2xx/3xx, WARNING for 4xx (and slow 2xx), ERROR for 5xx, with the full traceback when an exception escaped the route. Goes to both stderr (so journalctl catches it) and a rotating file the running user owns at ~/seren-logs/<service>-requests.log, so anyone debugging can tail it without sudo. If there is no home directory to put the file in, it logs to stderr only and says so, rather than refusing to start.

Request ids. Every request gets one: an inbound X-Request-Id is kept, so one string follows a call from Lodestar through Observatory into a service; otherwise a short random one is minted. It is on the log line and echoed back as X-Request-Id on the response, and routes can read it from request.state.request_id to pass along to the next hop.

It's parameterized, not hardcoded - service_name picks the logger name and log filename, env_prefix picks the env-var namespace:

from seren_meninges.auth import bearer_auth_middleware
from seren_sinew.request_log import RequestLoggingMiddleware

# Mount OUTERMOST - before auth - so 401s get logged too.
app.add_middleware(bearer_auth_middleware(token))                # inner
app.add_middleware(                                              # outer
    RequestLoggingMiddleware,
    service_name="seren-observatory",
    env_prefix="SEREN_AGENT",   # -> SEREN_AGENT_LOG_LEVEL / SEREN_AGENT_LOG_QUERY
)

Knobs (per env_prefix):

Running apps as needed (seren_sinew.orchestration, seren_sinew.ondemand). "I need this up" and "I'm done with it", said the same way by every Seren app: ensure / release messages, and a lease book that knows who holds what, for how long (a lease runs out unless it is renewed), and how long an app has sat with nobody holding it. A run policy per app says which apps run all the time and which run as needed:

decide() turns the book, what's running and the policies into "start this, stop that"; Lodestar runs it on a timer (its orchestration: block). For the caller, OnDemandTransport wraps an app's own httpx client: a refused connection asks Lodestar to start the other app and retries, and the lease is renewed while the calls keep coming.

from seren_sinew.ondemand import OnDemand, OnDemandTransport

probe = OnDemand(lodestar_url, "probe", holder="seren-workbench", token=lodestar_token)
client = httpx.AsyncClient(base_url=probe_url, transport=OnDemandTransport(probe))

What's coming

The cluster client, discovery and the DTOs that Lodestar and Observatory currently spell separately. Sinew is where the connective runtime code goes; Meninges stays the membrane.

Install

pip install seren-sinew

Light by design - depends only on starlette (already in every leaf via FastAPI), so it stays FastAPI-agnostic and adds nothing to a real install.

AGPL-3.0-or-later.