feat(adk): make AgentEx client HTTP timeouts configurable by env var

[chakrris]

Summary

The AgentEx client's HTTP timeout is fixed at the SDK default and cannot be changed from application code. This adds four environment variables to configure it, with defaults equal to today's values so nothing changes for an unconfigured process.

The problem

create_async_agentex_client() passes no timeout, so every client falls back to DEFAULT_TIMEOUT:

Timeout(connect=5.0, read=300, write=300, pool=300)

An application cannot override this. The ADK builds its own clients internally at 14 sites across messages, tasks, events and tracing, all through that factory, and none takes a timeout from the caller. No environment variable controlled it either, so wrapping the factory locally only covers the paths an app constructs itself, not the ADK's.

The connect timeout is the one that bites. An AgentEx backend accepts connections serially, so connect latency grows with the number of concurrent callers. Measured against a local backend with GET /readyz, a 10s client timeout, and no failures at any level:

Concurrent connects	p50	max
1	84 ms	84 ms
20	423 ms	452 ms
100	500 ms	537 ms
200	1,010 ms	1,075 ms

Latency is linear in concurrency, which is the signature of serialised accepts rather than slow request handling. An agent running 100 concurrent Temporal activities, each making ADK calls, crosses the 5s budget and fails with httpcore.ConnectTimeout. One run produced 197 such failures from a single activity type.

A 5s connect alongside a 300s read is also internally inconsistent: the client will wait five minutes for a response but only five seconds to open the socket.

What changed

The whole change is in src/agentex/lib/adk/utils/_modules/client.py. _timeout_from_env() reads four variables from os.environ, and create_async_agentex_client() applies the result when the caller passes no timeout:

AGENTEX_CLIENT_CONNECT_TIMEOUT_SECONDS   default 5.0
AGENTEX_CLIENT_READ_TIMEOUT_SECONDS      default 300.0
AGENTEX_CLIENT_WRITE_TIMEOUT_SECONDS     default 300.0
AGENTEX_CLIENT_POOL_TIMEOUT_SECONDS      default 300.0

Because all 14 internal construction sites route through that factory, one change covers messages, tasks, events and tracing.

Three properties worth checking in review:

• Defaults equal the current DEFAULT_TIMEOUT, so an unconfigured process behaves exactly as before.
• An explicit timeout= argument still wins over the environment.
• A malformed value raises a ValueError naming the variable, at the point the value is used.

Why not EnvironmentVariables

The first version of this PR declared the four values as fields on the shared EnvironmentVariables model, which is the repo's usual pattern. That turned out to be the wrong home for them, and the reasoning is worth recording because the failure was not obvious:

EnvironmentVariables.refresh() is called from about 20 places, none of which guard it, including AgentWorker startup and EnvAuth.auth_flow() on every authenticated request. A malformed timeout would therefore fail validation far from the client factory. The factory's try/except did not contain that; it only made the failure look handled at the one site that could have reported it clearly.

Removing that try/except exposed a second problem. agentex/lib/adk/utils/__init__.py constructs TemplatingModule() at module scope, and that constructor builds a client, so import agentex.lib.adk began requiring AGENT_NAME and ACP_URL to be set. The suppressed exception had been hiding an import-time dependency on a fully configured environment.

Reading os.environ directly avoids both. The shared model is untouched, so startup, authentication and import are unaffected, and a bad value affects only the timeout it describes.

Review guide

client.py is the entire behavioural change; it and its test are the only two files this PR touches. tests/lib/test_client_timeout_env.py covers the defaults, each override, the empty-string case, precedence of an explicit argument, that EnvAuth survives, the malformed-value error, and a regression test asserting the timeouts do not depend on the shared environment model.

Testing

uv sync requires uv >= 0.9 and this machine has 0.8.13, so I ran the suite through uvx with both packages installed editable. The 9 new tests pass, and tests/lib is 1028 passed / 3 skipped. pyright at the pinned 1.1.399 is clean on the touched files. The 12 errors in that run are all tests/lib/cli/test_agent_handlers.py raising on a Click DeprecationWarning under filterwarnings = error; they come from unpinned resolution in the ad-hoc environment rather than from uv.lock, and are unrelated to this change. ruff check and ruff format --check are clean on the touched files.

Greptile Summary

Adds environment-variable configuration for the AgentEx async client's connect, read, write, and pool timeouts.

• Preserves the SDK’s existing timeout values when variables are unset or blank.
• Gives explicit caller-provided timeout arguments precedence.
• Reads timeout settings independently of the shared environment model, containing malformed-value failures to client construction.
• Adds focused tests for defaults, overrides, precedence, malformed values, authentication attachment, and environment-model independence.

Confidence Score: 5/5

The PR appears safe to merge with no outstanding correctness, security, or repository-rule issues.

The previously reported shared-environment validation issue was fully addressed by reading timeout variables directly in the client factory, and that thread is resolved. The current implementation preserves existing defaults and explicit timeout precedence while limiting malformed configuration failures to client creation.

Important Files Changed

Filename	Overview
src/agentex/lib/adk/utils/_modules/client.py	Adds isolated environment parsing for all four HTTP timeout components while preserving explicit caller configuration.
tests/lib/test_client_timeout_env.py	Covers default and configured timeout behavior, malformed input, explicit precedence, authentication, and regression boundaries.

_{Reviews (4): Last reviewed commit: "Drop an unrelated file change from the b..." | Re-trigger Greptile}