[Bugfix] Fix mismatched logger format args and enable ruff PLE1205/PLE1206

[rajathpi]

Purpose

Three logger call sites in vllm/ pass arguments that do not match their
format string placeholders. Python's logging module formats lazily, so each
one raises TypeError inside emit(), prints a --- Logging error ---
traceback to stderr, and drops the intended diagnostic message entirely.

Site	Defect
vllm/v1/engine/tensor_ipc.py:151	Format string takes %d and %s, only sender_id is passed. The stale tensor count was never computed at all.
vllm/distributed/device_communicators/quick_all_reduce.py:175	Message has no placeholders; an f-string is passed as a second positional argument.
vllm/distributed/kv_transfer/kv_connector/v1/moriio/moriio_connector.py:1503	Same shape, at debug level.

The quick_all_reduce one is user-visible: setting an invalid
VLLM_ROCM_QUICK_REDUCE_QUANTIZATION prints a logging traceback instead of
the warning that names the supported levels.

The tensor_ipc one is not purely a formatting fix — %d had no
corresponding value, so the fix computes the count from the buffer being
discarded (if stale := sender.tensors.pop(mid) / len(stale)).

To stop the class of defect recurring, this also enables ruff's PLE1205
and PLE1206 in pyproject.toml. Both report zero violations across the
tree once these three sites are fixed, and reverting any of the three makes
ruff flag exactly that line.

Relationship to #39127

#39127 (open since April)
fixes the quick_all_reduce site with an identical rewrite, plus two
unrelated typos in that file. I am not able to drop that hunk here: enabling
PLE1205 requires all three sites to be clean, or CI fails on the rule
itself. The scope differs — that PR is one file, this one fixes the two
other occurrences and adds the lint gate that prevents new ones.

Happy to rebase and drop the overlapping hunk if #39127 lands first, or to
close this in its favour if maintainers would rather take the narrower
change and add the lint rule separately.

Test Plan

# Regression test for the tensor_ipc path, added to the existing suite
pytest tests/v1/test_tensor_ipc_queue.py tests/v1/test_serial_utils.py

# Lint, at the versions pinned in .pre-commit-config.yaml
uvx ruff@0.14.0 check --no-cache .
uvx ruff@0.14.0 format --check --no-cache .

# mypy, matching the pre-commit hook's isolated environment
python tools/pre_commit/mypy.py 3.12 \
  vllm/v1/engine/tensor_ipc.py \
  vllm/distributed/device_communicators/quick_all_reduce.py \
  vllm/distributed/kv_transfer/kv_connector/v1/moriio/moriio_connector.py \
  tests/v1/test_tensor_ipc_queue.py

Run on a CPU build (macOS/arm64, per .github/workflows/macos-smoke-test.yml).

Test Result

$ pytest tests/v1/test_tensor_ipc_queue.py tests/v1/test_serial_utils.py
22 passed, 3 skipped, 1 warning in 29.09s

The 3 skips are CUDA-only cases.

test_stale_message_discard_reports_tensor_count was verified to fail
without the tensor_ipc.py fix and pass with it. It asserts on
record.getMessage(), which raises if the placeholders and args disagree,
alongside the behavioural assertions (stale message dropped from the buffer,
current_message_id advanced, correct tensor returned):

$ git stash push vllm/v1/engine/tensor_ipc.py && pytest -k stale_message_discard
    result = receiver(
  File "vllm/v1/engine/tensor_ipc.py", line 151, in __call__
    logger.warning(
Message: 'Discarding %d stale tensors from sender %s'
Arguments: ('stale_sender',)
FAILED tests/v1/test_tensor_ipc_queue.py::test_stale_message_discard_reports_tensor_count
1 failed, 12 deselected

Lint and types:

$ uvx ruff@0.14.0 check --no-cache .
All checks passed!

$ uvx ruff@0.14.0 format --check --no-cache <changed files>
3 files already formatted

$ python tools/pre_commit/mypy.py 3.12 <changed files>
Success: no issues found in 3 source files
Success: no issues found in 1 source file

Confirming the lint gate has teeth — with the fixes reverted:

$ uvx ruff@0.14.0 check --no-cache vllm/
quick_all_reduce.py:175:13: PLE1205 Too many arguments for `logging` format string
moriio_connector.py:1503:21: PLE1205 Too many arguments for `logging` format string
tensor_ipc.py:151:33: PLE1206 Not enough arguments for `logging` format string

Not run: the ROCm (quick_all_reduce) and MoRIIO KV-transfer paths need
hardware I do not have. Both of those changes are message-rendering only,
with no behavioural change beyond the log line formatting correctly.

Model evaluation: not applicable — no change to model output, accuracy, or
serving behaviour.

Notes

This change was developed with AI assistance. I reviewed every changed line
and ran the tests listed above myself.

[claude]

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