Log Epochs in Console and Loggers

[yutong-xiang-97]

What has changed and why?

As the title suggests.

How has it been tested?

Manually:

[2026-04-01 13:02:26,052][INFO] Train Step 200/200 | Epoch 1 | train_loss: 28.8206 | lr: 0.00005457 | Profiling [ GPU Util 52.3% | GPU Max Mem  9760.3 MB | Step Time 0.27s | Data Time 0.03s |  121 img/s ]
[2026-04-01 13:02:26,149][INFO] Saving the last checkpoint to '/home/yutong/benchmark_logs/debug/1808_log_epoch/checkpoints/last.ckpt'
[2026-04-01 13:02:26,602][INFO] Exporting the last model to '/home/yutong/benchmark_logs/debug/1808_log_epoch/exported_models/exported_last.pt'
[2026-04-01 13:02:26,694][INFO] Validating...
[2026-04-01 13:02:28,281][INFO] Val Step   1/157 | Epoch 1 | Profiling [ GPU Util 30.0% | GPU Max Mem   874.0 MB | Step Time 1.58s | Data Time 0.79s |   20 img/s ]

Did you update CHANGELOG.md?

• Yes
• Not needed (internal change)

Did you update the documentation?

• Yes
• Not needed (internal change without effects for user)

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[yutong-xiang-97]

/review

[Copilot]

Pull request overview

Adds 1-based epoch information to both console step logs and structured logger outputs during training/validation, derived from the training step count, train dataloader length, and gradient accumulation.

Changes:

• Compute a current_epoch during the training loop and pass it into console logging for train/val steps.
• Add get_training_epoch(...) helper to derive a 1-based epoch from step and batch counts.
• Include epoch as a logged scalar in log_fabric(...) and document the addition in CHANGELOG.md.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/lightly_train/_commands/train_task.py	Computes current_epoch each step and plumbs it into console + fabric logging for train/val.
src/lightly_train/_commands/train_task_helpers.py	Adds epoch derivation helper and extends log_step / log_fabric to emit epoch.
CHANGELOG.md	Notes the new 1-based epoch logging behavior.