fix(router): repair main build breaks and deflake client timeout test

[pallasathena92]

Description

Problem

main currently fails cargo test compilation and cargo clippy -D warnings, which breaks the unit-tests lane on every PR merge build. Two concurrently merged changes raced: the owned-body dispatch refactor retyped the request body as Bytes and boxed PdSelectionFailure, while another branch merged code still wrapping the body in Bytes::from(...) and matching the selection failure unboxed. Each PR was green alone; their merge is not.

Separately, worker::http_client::tests::per_request_timeout_overrides_client_default is flaky: it races a zero-duration total timeout against a loopback echo response, and the fast local 200 wins often enough to fail roughly half of runs (reproduced locally at that rate; it also failed a PR lane today).

Solution

• Pass the already-Bytes body through directly at both dispatch sites and deref the boxed failure in the empty-fleet test — restores compile and clippy cleanliness.
• Deflake the timeout test: the client-default leg now targets a route that sleeps far past any deadline, so the zero timeout always fires; the per-request-override leg keeps the instant route. Same contract, no race.

Changes

• model_gateway/src/routers/http/pd_router.rs: drop redundant Bytes::from, deref boxed PdSelectionFailure in test_empty_worker_lists
• model_gateway/src/routers/http/router.rs: drop redundant Bytes::from
• model_gateway/src/worker/http_client.rs: add a hanging /hang route to the test echo server; aim the client-default timeout assertion at it

Test Plan

• cargo clippy -p smg --all-targets -- -D warnings passes (was 4 errors)
• cargo test -p smg --lib passes: 1789 passed, 0 failed (compilation was broken before)
• per_request_timeout_overrides_client_default passes 10/10 consecutive runs (previously ~half failed)
• cargo test -p smg --test inflight_tracker_test --test routing_tests passes (132 tests, closest integration coverage to the dispatch sites)
• cargo +nightly fmt clean

Checklist

• cargo +nightly fmt passes
• cargo clippy --all-targets -- -D warnings passes for the touched crate
• (Optional) Documentation updated
• (Optional) Please join us on Slack #sig-smg to discuss, review, and merge PRs

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 67b3a129-7957-4009-8f1d-2c5d861e9af9

📥 Commits

Reviewing files that changed from the base of the PR and between 4ff7d6e and 094527c.

📒 Files selected for processing (3)

• model_gateway/src/routers/http/pd_router.rs
• model_gateway/src/routers/http/router.rs
• model_gateway/src/worker/http_client.rs

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📝 Walkthrough

Summary by CodeRabbit

• Bug Fixes
  • Improved handling of HTTP request bodies for more reliable request processing.
  • Corrected empty-worker error handling in internal request selection.
  • Strengthened timeout behavior validation for requests with client-level and per-request timeout settings.

Walkthrough

The HTTP routers now forward existing Bytes bodies without conversion. The selection failure test matches the boxed value correctly. The HTTP client timeout test uses a hanging endpoint to verify client-level and per-request timeout behavior.

Changes

HTTP request handling

Layer / File(s)	Summary
Direct request body forwarding model_gateway/src/routers/http/pd_router.rs, model_gateway/src/routers/http/router.rs	The routers pass existing Bytes request bodies directly. The selection failure test dereferences the boxed failure before matching.
Timeout test behavior model_gateway/src/worker/http_client.rs	The test server adds a /hang endpoint. The timeout test uses /hang for the client default timeout and retains /probe for the per-request override.

Estimated code review effort: 2 (Simple) | ~10 minutes

Suggested reviewers: catherinesue, key4ng

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/pd-empty-fleet-test-deref

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_{Comment @coderabbitai help to get the list of available commands.}

[claude]

Clean post-merge fixup. All three changes are correct: redundant Bytes::from() removal matches the already-Bytes parameter types, the box deref aligns with the boxed PdSelectionFailure return type, and the hanging-route deflake soundly eliminates the timer race. No issues found.