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Superseded by #1276. Its complete registered-callback metadata-before-meter behavior, once-only dispatch and unchanged step-end ordering are retained in the current-main channel-loss lifecycle implementation. Both unique lifecycle tests are covered there with stronger keyword-forwarding checks. Independent immutable-source comparison and five lifecycle checks passed. Review #1276, then #1006 for compact source metrics.

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⚙️ Run configuration

Configuration used: Repository: ByteDance-Seed/VeOmni/.coderabbit.yaml

Review profile: CHILL

Plan: Advanced

Run ID: 5221ae75-62cc-4d51-a2a9-8c2acc3c133e

📥 Commits

Reviewing files that changed from the base of the PR and between 49cc654 and 46a4331.

📒 Files selected for processing (2)

• tests/trainer/test_channel_loss_callback.py
• veomni/trainer/base.py

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📝 Walkthrough

Walkthrough

BaseTrainer.on_step_begin now dispatches a registered channel-loss callback before other callbacks. Tests cover metadata visibility, step-end ordering, and unregistered callbacks.

Changes

Channel-loss callback ordering

Layer / File(s)	Summary
Ordered step-begin dispatch veomni/trainer/base.py	BaseTrainer calls the registered channel-loss callback before the generic callback loop and skips it during that loop. The callback ordering comment now documents the metadata and step-end sequence.
Callback lifecycle tests tests/trainer/test_channel_loss_callback.py	Tests verify metadata visibility, registered callback ordering, and omission of an unregistered channel-loss callback.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~15 minutes

Change: Bug fix

Sequence Diagram(s)

sequenceDiagram
  participant BaseTrainer
  participant channel_loss_callback
  participant self_callbacks
  BaseTrainer->>channel_loss_callback: on_step_begin(state, micro_batches, kwargs)
  BaseTrainer->>self_callbacks: iterate registered callbacks
  BaseTrainer->>self_callbacks: skip channel_loss_callback

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Suggested reviewers: coach257

Merge Risk: ⚪ Minimal · up to 46a43

The trainer preserves channel metadata visibility and avoids duplicate callback invocation; no concrete correctness or availability risk currently blocks merge.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 8.33% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 12 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the main change: capturing channel metadata before accounting in the trainer.

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✨ Finishing Touches

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