docs: add USER_GUIDE.md, tighten comments, fix CLI needing a DSN

The comment pass is prose-only: every distinct "why" is kept, the
narration around it is not. Verified by AST-comparing each changed file
against HEAD with docstrings stripped — only the two files below differ
in executable code.

Two real fixes fell out of the read-through:

* The CLI documented itself as never touching the database, then called
  load_settings(), which requires SVCFORGE_PG_DSN. It refused to start
  without a Postgres URL it never opens. It now has its own two-field
  ClientSettings; the orphaned api_url/api_token are dropped from
  Settings, where nothing else read them.
* repo/db.py had the DictRow alias comment and the ERROR_MAX_CHARS
  comment run together above the wrong symbol.

USER_GUIDE.md is the caller-facing guide the README only gestured at:
auth, catalog, every endpoint with curl, the lifecycle, the error table,
rate limiting, the CLI, client generation, an end-to-end poll loop.

It records two facts about the live deployment rather than documenting a
flow nobody can run. SVCFORGE_JWKS_URL points at a realm with no IdP
behind it, so the API logs "JWKS warm-up failed" at startup and every
/v1 request is a 401. And `helm repo list` in the worker returns no
repositories, so the three bitnamilegacy/ catalog entries cannot resolve
at provision time; only the oci:// entries can.

make lint clean, 76 unit + 111 integration tests pass.

services/api/deps.py

@@ -1,8 +1,8 @@
 """Dependency injection: how a handler gets a pool, a repo, a catalog, and a team.
 
 Everything expensive — the pool, the JWKS client, the parsed catalog — is built once in
-`lifespan` and parked on `app.state`. These functions only hand it out. A `Depends` that
-does I/O per request is a `Depends` that does that I/O on every request forever.
+`lifespan` and parked on `app.state`; these functions only hand it out. A `Depends` that
+does I/O per request does that I/O on every request forever.
 """
 
 from __future__ import annotations
@@ -22,10 +22,9 @@ from svcforge_core.repo.instances import InstanceRepo
 from svcforge_core.repo.tasks import TaskRepo
 from svcforge_core.settings import Settings
 
-# The algorithm allow-list is the whole point of naming algorithms explicitly.
-# `jwt.decode(..., algorithms=...)` without it accepts whatever the *token* claims in its
-# own header — including `none`, and including HS256 verified with the RSA public key as
-# an HMAC secret. Both are forgery. The list is not configuration.
+# The algorithm allow-list is not configuration. Without it, `jwt.decode` accepts whatever
+# the *token* claims in its own header — including `none`, and including HS256 verified
+# with the RSA public key as an HMAC secret. Both are forgery.
 ALLOWED_ALGORITHMS = ["RS256"]
 
 # What `auth_disabled` returns. Settings.check_production() refuses that flag in prod.
@@ -42,9 +41,9 @@ _bearer = HTTPBearer(auto_error=False)
 def _unauthorized() -> HTTPException:
     """One shape for every auth failure.
 
-    Expired, wrong issuer, wrong audience, bad signature, malformed, no header: all the
-    same 401 with the same body. Telling a caller *which* one turns the endpoint into an
-    oracle they can tune a forgery against.
+    Expired, wrong issuer, wrong audience, bad signature, malformed, no header: the same 401
+    with the same body. Naming which one turns the endpoint into an oracle a forger can tune
+    against.
     """
     return HTTPException(
         status_code=status.HTTP_401_UNAUTHORIZED,
@@ -68,8 +67,8 @@ async def get_pool(request: Request) -> DictPool:
 def get_catalog(request: Request) -> dict[str, CatalogEntry]:
     """The catalog, parsed once at startup.
 
-    Read from disk per request and a mid-flight edit to catalog.yaml changes the answer
-    between two requests of the same deploy. Load it at startup; a change is a restart.
+    Read per request, a mid-flight edit to catalog.yaml would change the answer between two
+    requests of the same deploy. A catalog change is a restart.
     """
     catalog: dict[str, CatalogEntry] = request.app.state.catalog
     return catalog
@@ -102,16 +101,14 @@ async def get_current_team(
 
     jwks_client: PyJWKClient | None = getattr(request.app.state, "jwks_client", None)
     if jwks_client is None:
-        # Auth is on but there is no key source. Fail closed. Answering 500 here would be
-        # honest about the cause and would also let a misconfigured deploy be told apart
-        # from a bad token; 401 is the same answer a forger gets.
+        # Auth is on but there is no key source. Fail closed. A 500 would be honest about
+        # the cause and would also let a forger tell a misconfigured deploy from a bad token.
         raise _unauthorized()
 
     try:
-        # PyJWKClient keeps its own TTL cache, so this is a dict lookup on the hot path.
-        # It is only blocking on a cache MISS (key rotation) — hence to_thread, which
-        # costs a thread hop we take a handful of times a day rather than an event loop
-        # stalled on someone else's HTTP call once per rotation.
+        # PyJWKClient keeps a TTL cache, so this is a dict lookup on the hot path and only
+        # blocks on a miss (key rotation) — hence to_thread, a thread hop a few times a day
+        # rather than an event loop stalled on someone else's HTTP call.
         signing_key = await _signing_key(jwks_client, creds.credentials)
         claims: dict[str, Any] = jwt.decode(
             creds.credentials,
@@ -139,10 +136,9 @@ async def get_current_team(
 async def _signing_key(client: PyJWKClient, token: str) -> jwt.PyJWK:
     """Fetch the signing key off the event loop.
 
-    PyJWKClient.get_signing_key_from_jwt() does a synchronous urlopen on a cache miss.
-    Called directly from `async def`, that blocks the loop — every other in-flight request
-    on this worker stops until the identity provider answers, and if it hangs, so does the
-    pod, and /readyz keeps saying it is fine.
+    `get_signing_key_from_jwt()` does a synchronous urlopen on a cache miss. Called directly
+    from `async def` it blocks the loop: every other in-flight request stops until the IdP
+    answers, and if the IdP hangs so does the pod, with /readyz still saying it is fine.
     """
     return await asyncio.to_thread(client.get_signing_key_from_jwt, token)
 
@@ -159,11 +155,10 @@ async def rate_limit(
 ) -> None:
     """Per-team rate limiting. One Redis command per check, and it fails OPEN.
 
-    Failing open is the entire policy. Redis holds derived state; losing it must degrade
-    the platform, never stop it. A limiter that fails closed converts a cache outage into
-    a total outage, which is a strictly worse incident than the burst it was protecting
-    against — so `RateLimiter.check` swallows its own errors and returns `allowed=True`.
-    The 429 below therefore only ever comes from a real, counted overage.
+    Redis holds derived state, so losing it must degrade the platform rather than stop it: a
+    limiter that fails closed turns a cache outage into a total outage, a worse incident
+    than the burst it was guarding against. `RateLimiter.check` swallows its own errors and
+    returns `allowed=True`, so the 429 below only comes from a real, counted overage.
     """
     limiter = get_rate_limiter(request)
     if limiter is None:

services/api/main.py

@@ -1,7 +1,7 @@
 """The app factory and its lifespan.
 
-`create_app(settings)` is a factory, not a module-level `app = FastAPI()`, for one reason:
-a test needs an app pointed at a throwaway Postgres, and an import-time app reads the real
+`create_app(settings)` is a factory rather than a module-level `app = FastAPI()` because a
+test needs an app pointed at a throwaway Postgres, and an import-time app reads the real
 environment at import time — before any fixture can say otherwise.
 """
 
@@ -32,23 +32,21 @@ log = obs.get_logger("svcforge.api")
 async def lifespan(app: FastAPI) -> AsyncIterator[None]:
     """Open the pool, yield, close the pool.
 
-    A lifespan context, not the deprecated startup/shutdown event decorators: those cannot
-    express "this resource lives for exactly as long as the app", and give you no place to
-    put the teardown next to the setup. Closing the pool matters — an unclosed pool means
-    connections linger server-side after SIGTERM, and on a pooled Postgres with a small
-    connection budget a few rolling deploys exhaust it.
+    A lifespan context, not the deprecated startup/shutdown decorators: those cannot express
+    "this resource lives exactly as long as the app" and leave no place to put teardown next
+    to setup. Closing matters — an unclosed pool leaves connections open server-side after
+    SIGTERM, and on a pooled Postgres with a small budget a few rolling deploys exhaust it.
 
-    (The old decorator's name is spelled nowhere in this package on purpose: CI greps for
-    the literal string, and a comment quoting it fails the gate just as loudly as a call.)
+    (The old decorator's name is spelled nowhere here on purpose: CI greps for the literal
+    string, so a comment quoting it fails the gate as loudly as a call would.)
     """
     settings: Settings = app.state.settings
 
     app.state.catalog = load_catalog(settings.catalog_path)
 
-    # Redis is optional by construction. `make_redis` returns None when no DSN is set, and
-    # every consumer treats None as "skip" — so a deployment without Redis loses rate
-    # limiting and keeps everything else. Built here rather than per request because a
-    # connection pool per request is a connection pool per request.
+    # Redis is optional by construction: `make_redis` returns None when no DSN is set and
+    # every consumer treats None as "skip", so a deployment without Redis loses rate
+    # limiting and keeps everything else. Built once here, not per request.
     redis = make_redis(settings)
     app.state.redis = redis
     app.state.rate_limiter = (
@@ -61,16 +59,16 @@ async def lifespan(app: FastAPI) -> AsyncIterator[None]:
     await pool.open(wait=True)
     app.state.pool = pool
 
-    # The pool is open from here on, so everything below is inside the try: an exception
-    # in JWKS setup must still close it, or a crash-looping pod leaks a connection per
-    # restart until the database refuses new ones.
+    # The pool is open from here, so everything below is inside the try: an exception in
+    # JWKS setup must still close it, or a crash-looping pod leaks a connection per restart
+    # until the database refuses new ones.
     try:
         if settings.jwks_url and not settings.auth_disabled:
             client = PyJWKClient(settings.jwks_url, cache_keys=True, lifespan=300)
             app.state.jwks_client = client
-            # Warm the cache off the loop so the first authenticated request does not pay
-            # a blocking urlopen. Best-effort: a slow identity provider must not stop the
-            # pod from starting — a cache miss later just costs one to_thread hop.
+            # Warm the cache off the loop so the first authenticated request does not pay a
+            # blocking urlopen. Best-effort: a slow IdP must not stop the pod from starting,
+            # and a miss later costs one to_thread hop.
             try:
                 await asyncio.to_thread(client.get_signing_keys)
             except Exception:  # deliberate catch-all: startup must not hinge on the IdP being up
@@ -87,9 +85,8 @@ async def lifespan(app: FastAPI) -> AsyncIterator[None]:
 
 # --------------------------------------------------------------------------- API docs
 
-# Everything a caller needs that the generated schema cannot express on its own. Kept next
-# to create_app rather than in a README because /docs is what someone integrating actually
-# reads, and a README in this repo is not something they have.
+# What the generated schema cannot express. Kept next to create_app because /docs is what
+# someone integrating reads, and they do not have this repo. USER_GUIDE.md is the longer form.
 API_DESCRIPTION = """
 Provision managed service instances into Kubernetes. The catalog offers Elasticsearch,
 Redis and Postgres, plus two deliberately tiny entries — `podinfo` and `nginx` — for
@@ -144,21 +141,19 @@ OPENAPI_TAGS = [
 async def _http_exception_handler(request: Request, exc: Exception) -> JSONResponse:
     """Render HTTPException bodies as ErrorBody, so every error has one shape.
 
-    Handlers raise `detail={"code": ..., "message": ...}`; FastAPI's default would nest
-    that under `{"detail": {...}}`. Plain-string details (raised by FastAPI itself, e.g.
-    a 405) are wrapped so clients never have to branch on the body's type.
+    Handlers raise `detail={"code": ..., "message": ...}`, which FastAPI's default would
+    nest under `{"detail": {...}}`. Plain-string details (a framework 405, say) are wrapped
+    so clients never branch on the body's type.
 
-    Registered on starlette's HTTPException, not fastapi's. fastapi.HTTPException is a
-    subclass, and Starlette matches handlers by walking type(exc).__mro__, so a handler
-    keyed on the subclass never fires for a framework-raised 404 or 405 — which are
-    starlette.HTTPException instances. Keying on the parent catches both: app handlers
-    raise the FastAPI subclass with a dict detail, the framework raises the parent with a
-    str detail, and the branch below renders each into ErrorBody.
+    Registered on starlette's HTTPException, not fastapi's. The FastAPI class is a subclass
+    and Starlette matches handlers by walking `type(exc).__mro__`, so a handler keyed on the
+    subclass never fires for a framework-raised 404 or 405. Keying on the parent catches
+    both, and the branch below renders each into ErrorBody.
     """
     assert isinstance(exc, HTTPException)  # noqa: S101 - registered only for HTTPException
-    # Widened to object deliberately. Starlette types `detail` as str, but FastAPI passes
-    # through whatever a handler raised — our handlers raise dicts. Narrowing off the
-    # declared type would make mypy call the dict branch unreachable and delete it.
+    # Widened to object deliberately: Starlette types `detail` as str, but FastAPI passes
+    # through whatever a handler raised, and ours raise dicts. Narrowing off the declared
+    # type would let mypy call the dict branch unreachable and delete it.
     detail: object = exc.detail
     if isinstance(detail, dict) and "code" in detail and "message" in detail:
         body = ErrorBody(code=str(detail["code"]), message=str(detail["message"]))
@@ -170,10 +165,9 @@ async def _http_exception_handler(request: Request, exc: Exception) -> JSONRespo
 async def _validation_exception_handler(request: Request, exc: Exception) -> JSONResponse:
     """Render request-validation failures as ErrorBody too.
 
-    A body that fails validation (a forbidden extra field, a bad type, an out-of-range
-    ttl_days) raises RequestValidationError, which the HTTPException handler above never
-    sees. Without this it returns FastAPI's default `{"detail": [...]}` — a second 422 shape
-    alongside the ErrorBody 422s the handlers raise. This gives every 422 one shape.
+    A forbidden extra field, a bad type or an out-of-range ttl_days raises
+    RequestValidationError, which the handler above never sees. Without this, FastAPI's
+    default `{"detail": [...]}` is a second 422 shape alongside the handlers' ErrorBody.
     """
     assert isinstance(exc, RequestValidationError)  # noqa: S101 - registered only for this
     return JSONResponse(
@@ -186,22 +180,20 @@ def create_app(settings: Settings | None = None) -> FastAPI:
     """App factory: lifespan, routers, exception handler, /metrics."""
     settings = settings or load_settings()
 
-    # FIRST, before any router is built and before any logger is bound. Without this the
-    # API is the one service of three that never configures structlog: its lines go out
-    # through logging.lastResort as bare text on stderr with no service, no trace_id and
-    # no JSON envelope — a parse failure in the collector, and unattributable in Loki.
+    # FIRST, before any router is built and any logger is bound. Without it the API is the
+    # one service of three that never configures structlog, and its lines go out through
+    # logging.lastResort as bare text on stderr — no service, no trace_id, no JSON envelope.
     # `settings.log_json` was silently inert here for the same reason.
     obs.setup("svcforge-api", settings)
 
     # Refuse the dev escape hatches when SVCFORGE_ENVIRONMENT says this is not a laptop.
-    # Called unconditionally and early: a check that only runs from a branch someone
-    # remembered to write is a check that does not run.
+    # Unconditional and early: a check that runs only from a branch someone remembered to
+    # write is a check that does not run.
     settings.check_production()
 
-    # The description is the API's documentation. FastAPI renders it as markdown at /docs,
-    # and it is the only place a caller who does not have this repo can learn the two things
-    # that are not obvious from the schema: every write is asynchronous, and the instance
-    # lifecycle is a state machine they have to poll.
+    # The description is the API's documentation, rendered as markdown at /docs. It is the
+    # only place a caller without this repo learns the two things the schema cannot say:
+    # every write is asynchronous, and the lifecycle is a state machine they have to poll.
     app = FastAPI(
         title="svcforge",
         version="0.1.0",
@@ -227,7 +219,6 @@ def app() -> FastAPI:
     return create_app()
 
 
-# There is deliberately no `if __name__ == "__main__"` here. `services/api/__main__.py` is
-# the single entrypoint, and the image's ENTRYPOINT uses it. A second one in this module
-# drifted from it — different log_level, different access_log — so `python -m services.api`
-# and `python services/api/main.py` started the same app two different ways.
+# No `if __name__ == "__main__"` here on purpose. `services/api/__main__.py` is the single
+# entrypoint and the image's ENTRYPOINT uses it. A second one in this module drifted from
+# it — different log_level, different access_log — so the same app started two ways.

services/api/models.py

@@ -1,9 +1,8 @@
-"""Wire types.
+"""Wire types, deliberately not the domain models.
 
-These are deliberately NOT the domain models. `Instance` carries `team`, `namespace` and
-`release_name` — placement details a tenant has no business seeing and no business
-setting. The response model is the allow-list that keeps them off the wire, which is why
-it is written out by hand instead of derived from `Instance`.
+`Instance` carries `team`, `namespace` and `release_name` — placement details a tenant has
+no business seeing or setting. The response model is the allow-list that keeps them off the
+wire, which is why it is written by hand instead of derived from `Instance`.
 """
 
 from __future__ import annotations
@@ -19,9 +18,8 @@ class CreateInstanceRequest(BaseModel):
     """What a tenant may ask for.
 
     `service_type` and `size` are plain strings, not enums: the catalog is data loaded at
-    runtime, so baking its keys into a type would mean a redeploy to add a service type,
-    and a 422 (schema) where the spec wants a 404 (unknown resource). They are validated
-    against the catalog in the handler.
+    runtime, so baking its keys into a type would mean a redeploy to add a service type and
+    a 422 where the spec wants a 404. The handler validates them against the catalog.
     """
 
     model_config = ConfigDict(

services/api/routes/health.py

@@ -3,11 +3,11 @@
 The distinction between the first two is the difference between a 30-second blip and a
 fleet-wide outage:
 
-* `/healthz` (liveness) answers "is this process wedged?" A failure here gets the
-  container KILLED. It must therefore touch NOTHING external. Wire it to the DB and a
-  20-second Postgres failover restarts every pod at once; they come back, find the DB
-  still down, and CrashLoopBackOff with exponential restart delays — so the fleet is now
-  down for minutes after the database recovered.
+* `/healthz` (liveness) answers "is this process wedged?" A failure here KILLS the
+  container, so it must touch nothing external. Wired to the DB, a 20-second Postgres
+  failover restarts every pod at once; they come back, find the DB still down, and
+  CrashLoopBackOff with exponential delays — the fleet stays down for minutes after the
+  database recovered.
 * `/readyz` (readiness) answers "should this pod get traffic?" A failure here only removes
   it from the Service endpoints. It is allowed to check dependencies, and it recovers by
   itself the moment the check passes.
@@ -26,10 +26,10 @@ from services.api.models import ErrorBody
 
 router = APIRouter(tags=["ops"])
 
-# No PROMETHEUS_MULTIPROC_DIR here, deliberately: it exists for prefork servers where each
-# worker process holds a slice of the counters. One uvicorn process per container means
-# the default in-process registry is already correct, and multiproc mode would add a
-# shared temp dir, a cleanup obligation, and a class of stale-file bugs for nothing.
+# No PROMETHEUS_MULTIPROC_DIR, deliberately: it exists for prefork servers where each
+# process holds a slice of the counters. One uvicorn process per container makes the
+# in-process registry correct, and multiproc mode would add a shared temp dir, a cleanup
+# obligation, and a class of stale-file bugs for nothing.
 
 
 @router.get("/healthz", status_code=status.HTTP_200_OK)
@@ -45,10 +45,9 @@ async def healthz() -> dict[str, str]:
 async def readyz(pool: PoolDep) -> dict[str, str]:
     """Readiness. Postgres only.
 
-    Postgres-only is the rule, and Redis is the temptation. Redis holds derived state —
-    rate-limit buckets, caches — and everything degrades gracefully without it. Put it in
-    this check and an Upstash hiccup marks every pod unready, Kubernetes empties the
-    Service, and a cache outage becomes a total API outage.
+    Redis is the temptation and stays out: it holds derived state that degrades gracefully,
+    so checking it here would let an Upstash hiccup mark every pod unready, empty the
+    Service, and turn a cache outage into a total API outage.
     """
     try:
         async with pool.connection() as conn, conn.cursor() as cur:
@@ -68,14 +67,13 @@ async def readyz(pool: PoolDep) -> dict[str, str]:
 async def metrics(request: Request) -> Response:
     """The Prometheus scrape endpoint.
 
-    A route rather than `app.mount("/metrics", make_asgi_app())`, for two reasons. A
-    Starlette `Mount` compiles to `^/metrics(?P<path>/.*)$`, which does not match a bare
-    `/metrics` — the exact URL every scrape config uses — and a `Mount` is invisible to
-    OpenAPI, while the deliverable asks for `/metrics` in `openapi.json`.
+    A route rather than `app.mount("/metrics", make_asgi_app())`: a Starlette `Mount`
+    compiles to `^/metrics(?P<path>/.*)$`, which does not match the bare `/metrics` every
+    scrape config uses, and a Mount is invisible to OpenAPI.
 
-    The encoding is still prometheus_client's: `choose_encoder` reads the Accept header and
-    picks the exposition format (Prometheus text vs OpenMetrics) with its matching content
-    type. Hand-rolling either is how you end up serving text/plain that a scraper rejects.
+    The encoding stays prometheus_client's — `choose_encoder` reads Accept and picks the
+    exposition format with its matching content type. Hand-rolling it serves text/plain a
+    scraper rejects.
     """
     encoder, content_type = choose_encoder(request.headers.get("Accept", ""))
     return Response(content=encoder(REGISTRY), media_type=content_type)

services/api/routes/instances.py

@@ -1,12 +1,12 @@
 """The tenant-facing API.
 
-Two rules run through every handler here:
+Two rules run through every handler:
 
-* **AuthZ is the WHERE clause.** No handler ever compares `inst.team` to the caller's
-  team, because the repo never returns another team's row to compare. A wrong-team id is
-  a 404. 403 would confirm the id exists, which is the leak.
-* **The instance and its task commit together.** A committed instance with no task is an
-  instance that never provisions and that nothing will ever retry.
+* **AuthZ is the WHERE clause.** No handler compares `inst.team` to the caller's team,
+  because the repo never returns another team's row to compare. A wrong-team id is a 404;
+  403 would confirm the id exists.
+* **The instance and its task commit together.** A committed instance with no task never
+  provisions and nothing retries it.
 """
 
 from __future__ import annotations
@@ -30,9 +30,9 @@ from services.api.models import CreateInstanceRequest, ErrorBody, InstanceRespon
 from svcforge_core.domain.models import CatalogEntry, Instance, TaskKind
 from svcforge_core.domain.states import IllegalTransition, InstanceState, transition
 
-# Declared on the router so every error shape lands in openapi.json under ErrorBody.
-# The exception handler already renders this at runtime; without declaring it, generated
-# clients see the contract for 2xx only and invent their own guess for the rest.
+# Declared on the router so every error shape lands in openapi.json under ErrorBody. The
+# exception handler already renders these at runtime; undeclared, a generated client sees
+# the contract for 2xx only and guesses the rest.
 ERROR_RESPONSES: dict[int | str, dict[str, Any]] = {
     401: {"model": ErrorBody, "description": "Missing or invalid credentials"},
     404: {"model": ErrorBody, "description": "No such instance, or not this team's"},
@@ -46,14 +46,12 @@ router = APIRouter(prefix="/v1/instances", tags=["instances"], responses=ERROR_R
 def release_name_for(team: str, service_type: str, instance_id: UUID) -> str:
     """The helm release name. Deterministic, and `unique` in the schema.
 
-    This is the idempotency anchor. A worker that dies after `helm install` but before it
-    marks the task done will retry, compute the same name, and `helm upgrade --install`
-    onto the same release instead of creating a second one. Derive it from anything that
-    is not already durable — a timestamp, a random suffix, the retry count — and a retry
-    provisions a duplicate.
+    The idempotency anchor: a worker that dies after `helm install` but before marking the
+    task done retries, computes the same name, and upgrades the same release instead of
+    creating a second one. Derive it from anything not already durable — a timestamp, a
+    random suffix, the retry count — and a retry provisions a duplicate.
 
-    Truncated to the uuid's first 8 chars to stay inside the 53-char limit helm imposes
-    on release names (Kubernetes label values, minus room for chart-generated suffixes).
+    Truncated to the uuid's first 8 chars to stay inside helm's 53-char release-name limit.
     """
     return f"{team}-{service_type}-{str(instance_id)[:8]}"
 
@@ -66,9 +64,8 @@ def namespace_for(team: str) -> str:
 def _resolve(catalog: dict[str, CatalogEntry], service_type: str, size: str) -> CatalogEntry:
     """Look up service_type + size, or raise the right 4xx.
 
-    The two failures are different HTTP problems and the spec asks for different codes:
-    an unknown service_type is a resource that does not exist (404); an unknown size for a
-    real service_type is a body the server understood and cannot process (422).
+    Two different HTTP problems: an unknown service_type is a resource that does not exist
+    (404), an unknown size for a real one is a body understood and unprocessable (422).
     """
     entry = catalog.get(service_type)
     if entry is None:
@@ -107,9 +104,9 @@ async def create_instance(
 ) -> Instance:
     """Accept a provisioning request. 202, never 201.
 
-    Nothing is provisioned when this returns. The row exists and a task is queued; a
-    worker will do the work seconds or minutes from now. 201 Created would be a lie about
-    a resource that does not exist yet, and clients would stop polling.
+    Nothing is provisioned when this returns: the row exists and a task is queued, and a
+    worker does the work seconds or minutes later. 201 Created would be a lie about a
+    resource that does not exist yet, and clients would stop polling.
     """
     entry = _resolve(catalog, body.service_type, body.size)
 
@@ -123,9 +120,9 @@ async def create_instance(
         state=InstanceState.REQUESTED,
         namespace=namespace_for(team),
         release_name=release_name_for(team, body.service_type, instance_id),
-        # Pinned from the catalog AT CREATION TIME, not read from the catalog later.
-        # This column records what is actually deployed; bumping catalog.yaml must show up
-        # as drift the reconciler can see, not silently rewrite history.
+        # Pinned at creation time, not read from the catalog later. The column records what
+        # is deployed, so bumping catalog.yaml shows up as drift the reconciler can see
+        # rather than silently rewriting history.
         chart_version=entry.chart_version,
         expires_at=now + timedelta(days=body.ttl_days) if body.ttl_days is not None else None,
         created_at=now,
@@ -181,12 +178,11 @@ async def delete_instance(
 ) -> Instance:
     """state -> deleting, enqueue deprovision. 202: the helm uninstall has not happened yet.
 
-    Ordering note. `InstanceRepo.update_state` owns its own connection, so the CAS and the
-    enqueue cannot share one transaction without reaching around the repo. Given two
-    statements, the order is chosen for its failure mode: CAS first, enqueue second. A
-    crash in between leaves an instance in `deleting` with no task, which the reconciler's
-    sweep re-enqueues. The other order leaves a deprovision task pointing at a `ready`
-    instance, and a worker would tear down a live service nobody asked to delete.
+    `InstanceRepo.update_state` owns its own connection, so the CAS and the enqueue cannot
+    share a transaction without reaching around the repo. Given two statements, the order is
+    chosen for its failure mode: a crash between CAS and enqueue leaves an instance in
+    `deleting` with no task, which the reconciler's sweep re-enqueues. The reverse would
+    leave a deprovision task on a `ready` instance and tear down a live service.
     """
     inst = await instances.get(instance_id, team)
     if inst is None: