refactor phase 7: asyncio.timeout, ASYNC109 noqa for public API

Replace 3x asyncio.wait_for(future, timeout=t) with
async with asyncio.timeout(t): await future
in runtime.job (request_human_input/choice timeout paths) and
client.request (3.11+ structured-cancellation primitive). Fan-out is
already TaskGroup throughout the runtime; no gather sites.

ASYNC109 ("async function with a timeout parameter") fires on
client.request because the timeout is part of the public API. Add a
per-line noqa with reason on the parameter. For test helpers that use
'timeout' as a polling-budget wall-clock value rather than as an
asyncio.timeout argument, add ASYNC109 to the tests/** per-file
ignore.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: nficano

pyproject.toml

@@ -84,7 +84,9 @@ ignore = [
 [tool.ruff.lint.per-file-ignores]
 # Tools (`async def f(ctx, args)`) and inbound handlers (`async def h(env)`)
 # have protocol-mandated signatures; unused-arg lints are noise here.
-"tests/**" = ["B011", "ARG001", "ARG002"]
+# ASYNC109 in tests fires on test-helper polling deadlines that use a
+# `timeout=` parameter as a wall-clock budget rather than asyncio.timeout().
+"tests/**" = ["B011", "ARG001", "ARG002", "ASYNC109"]
 "examples/**" = ["ARG001", "ARG002"]
 
 [tool.ruff.lint.pydocstyle]

src/arcp/client/client.py

@@ -129,7 +129,12 @@ async def send(self, envelope: Envelope) -> None:
             raise RuntimeError("client is not open")
         await self.transport.send(envelope.to_wire())
 
-    async def request(self, envelope: Envelope, *, timeout: float | None = None) -> Envelope:
+    async def request(
+        self,
+        envelope: Envelope,
+        *,
+        timeout: float | None = None,  # noqa: ASYNC109 — public API; pass-through to asyncio.timeout below.
+    ) -> Envelope:
         """Send a command and await the envelope whose ``correlation_id`` matches.
 
         ``correlation_id`` matching is keyed on the outbound envelope's ``id``.
@@ -142,7 +147,8 @@ async def request(self, envelope: Envelope, *, timeout: float | None = None) ->
         self._waiters[envelope.id] = future
         try:
             await self.transport.send(envelope.to_wire())
-            return await asyncio.wait_for(future, timeout=timeout)
+            async with asyncio.timeout(timeout):
+                return await future
         finally:
             self._waiters.pop(envelope.id, None)
 

src/arcp/runtime/job.py

@@ -259,7 +259,8 @@ async def request_human_input(
         await self.sink(envelope)
         timeout = max(0.0, _seconds_until(expires_at))
         try:
-            response = await asyncio.wait_for(future, timeout=timeout)
+            async with asyncio.timeout(timeout):
+                response = await future
         except TimeoutError as exc:
             self.pending.cancel(request_id)
             if default is not None:
@@ -327,7 +328,8 @@ async def request_human_choice(
         await self.sink(envelope)
         timeout = max(0.0, _seconds_until(expires_at))
         try:
-            response = await asyncio.wait_for(future, timeout=timeout)
+            async with asyncio.timeout(timeout):
+                response = await future
         except TimeoutError as exc:
             self.pending.cancel(request_id)
             self.job.state = prior_state