fix(pawnio): cap broker SMBus batch delay

[hyperb1iss]

Motivation

• The broker accepted unbounded Delay { duration_ms } operations in SmBusXferBatch and executed thread::sleep while holding the global buses mutex, allowing a local interactive process to block broker worker threads and cause an availability DoS.

Description

• Add a broker-side cap MAX_BATCH_DELAY_MS = 1_000 and validate incoming batch delays with a new validate_batch_delay_ms helper.
• Reject oversized delays early by returning PawnIoError::InvalidInput instead of sleeping for the supplied duration inside BrokerState::smbus_xfer_batch.
• Preserve existing behavior for valid delays by still performing thread::sleep for values at-or-below the cap.
• Add a unit test batch_delay_rejects_values_above_maximum to assert that values above the cap are rejected.

Testing

• Ran cargo test -p hypercolor-windows-pawnio --lib and the crate built and tested successfully in this environment (test runner completed with no failing tests).
• The added unit test validates the delay validation helper and was exercised by the test run (no test failures).

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Codex Task

Summary by CodeRabbit

Release Notes

• Bug Fixes

  • Batch operations with delays exceeding the maximum allowed duration are now rejected with an error.

• Tests

  • Added validation test for batch delay constraints.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 88ee50a5-8f35-4656-9d14-0a127fb5f966

📥 Commits

Reviewing files that changed from the base of the PR and between 7547799 and c55bcb0.

📒 Files selected for processing (1)

• crates/hypercolor-windows-pawnio/src/windows/broker.rs

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📝 Walkthrough

Walkthrough

This PR adds input validation to SMBus batch delay operations by introducing a maximum delay duration constant and validation function. The validation is integrated into batch execution to reject oversized delays, and unit tests verify the rejection behavior.

Changes

Batch Delay Validation

Layer / File(s)	Summary
Batch delay validation constant and function crates/hypercolor-windows-pawnio/src/windows/broker.rs	MAX_BATCH_DELAY_MS constant defines the upper bound, and validate_batch_delay_ms returns PawnIoError::InvalidInput when duration_ms exceeds the maximum.
Batch execution integration crates/hypercolor-windows-pawnio/src/windows/broker.rs	Batch Delay operation handler calls validate_batch_delay_ms before performing thread::sleep, enforcing the constraint at the execution point.
Delay validation tests crates/hypercolor-windows-pawnio/src/windows/broker.rs	Test module imports MAX_BATCH_DELAY_MS and new unit test batch_delay_rejects_values_above_maximum verifies validation rejects delays above the maximum.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Poem

🐰 A bunny checks batch delays with care,
Setting a maximum duration bound fair,
When sleeps run too long, we say "nay!"—
Validation ensures they obey the way! 🕐

✨ 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 codex/fix-unbounded-delays-in-smbus-broker

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