fix(tf): accept standard checkpoint inputs in change-bias

[wanghan-iapcm]

Problem

The TensorFlow change-bias dispatcher only accepts inputs ending in .pb, .pbtxt, .ckpt, .meta, .data, or .index, and rejects everything else with RuntimeError("The model provided must be a checkpoint file or frozen model file (.pb)").

However, the CLI examples and the frozen-model fallback message recommend passing a checkpoint directory, and real TensorFlow checkpoint prefixes commonly look like model.ckpt-1000. A checkpoint directory has no recognized suffix, and a model.ckpt-1000 prefix ends in -1000, so both are rejected before _change_bias_checkpoint_file() — which already resolves the checkpoint via the checkpoint state file — can run.

Fix

Route suffix-less inputs to the checkpoint handler when a TensorFlow checkpoint state file is present in the effective directory (the input itself if it is a directory, otherwise its parent). Inputs without such a state file still raise the original error. _change_bias_checkpoint_file() now also resolves checkpoint_dir correctly when the input is a directory.

Test

source/tests/tf/test_change_bias.py previously exercised only .pb, .ckpt, and bad-suffix inputs, never a bare directory or a ckpt-<step> prefix. Two new tests mock _change_bias_checkpoint_file and assert it is invoked for a model.ckpt-1000 prefix and for a checkpoint directory that contain a checkpoint state file. On the current dispatcher both raise the "checkpoint file or frozen model file" RuntimeError before reaching the handler; after the fix both route correctly. The existing rejection tests (e.g. a model.xyz file with no checkpoint state file) still raise.

Fix #5683

Summary by CodeRabbit

• Bug Fixes

  • Improved handling of checkpoint inputs so bias changes now work reliably for both checkpoint file prefixes and checkpoint directories.
  • Unrecognized input paths are now treated as checkpoint-based inputs only when a valid checkpoint state is present, reducing incorrect routing.

• Tests

  • Added coverage for checkpoint prefix and directory cases to verify the correct bias-change path is used.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: b40f37b4-02a1-4cc7-89aa-c93d0f65950d

📥 Commits

Reviewing files that changed from the base of the PR and between b22a3c3 and 4027229.

📒 Files selected for processing (2)

• deepmd/tf/entrypoints/change_bias.py
• source/tests/tf/test_change_bias.py

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📝 Walkthrough

Walkthrough

The change_bias() entrypoint now recognizes checkpoint directories and checkpoint prefixes with step suffixes (e.g., model.ckpt-1000) by checking for a TensorFlow checkpoint state file, routing such inputs to _change_bias_checkpoint_file(). That helper's checkpoint_dir derivation was also updated to handle directory inputs. Corresponding unit tests were added.

Changes

Checkpoint Input Handling

Layer / File(s)	Summary
Fallback routing for checkpoint directories and prefixes deepmd/tf/entrypoints/change_bias.py	Adds a fallback branch for unrecognized INPUT suffixes that checks for a checkpoint state file and routes to _change_bias_checkpoint_file(); updates checkpoint_dir derivation to support both directory and prefix inputs.
Tests for new checkpoint routing source/tests/tf/test_change_bias.py	Imports the module via importlib to patch internal helpers, and adds tests verifying checkpoint prefix and checkpoint directory inputs are routed to _change_bias_checkpoint_file.

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

Sequence Diagram(s)

sequenceDiagram
  participant User
  participant change_bias
  participant FileSystem
  participant ChangeBiasCheckpointFile as _change_bias_checkpoint_file

  User->>change_bias: INPUT (checkpoint dir or prefix)
  change_bias->>change_bias: check known file suffixes
  alt suffix unrecognized
    change_bias->>FileSystem: check checkpoint_dir/checkpoint exists
    FileSystem-->>change_bias: exists
    change_bias->>ChangeBiasCheckpointFile: forward INPUT and args
    ChangeBiasCheckpointFile->>ChangeBiasCheckpointFile: derive checkpoint_dir (dir or parent)
  else suffix recognized
    change_bias->>change_bias: existing dispatch logic
  end

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Suggested labels: Python

Suggested reviewers: njzjz, iProzd

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main fix: accepting standard TensorFlow checkpoint inputs in change-bias.
Linked Issues check	✅ Passed	The code now accepts checkpoint directories and prefixes when checkpoint state exists, matching the linked issue's requirements.
Out of Scope Changes check	✅ Passed	The changes stay focused on change-bias checkpoint handling and its tests, with no obvious unrelated additions.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.70%. Comparing base (0e5c170) to head (4027229).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5702      +/-   ##
==========================================
- Coverage   81.97%   81.70%   -0.27%     
==========================================
  Files         959      966       +7     
  Lines      105748   106151     +403     
  Branches     4102     4139      +37     
==========================================
+ Hits        86684    86731      +47     
- Misses      17573    17901     +328     
- Partials     1491     1519      +28     

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[njzjz-bot]

Looks good to me. The fallback dispatch now accepts both checkpoint directories and standard TensorFlow checkpoint prefixes when a checkpoint state file is present, while preserving the existing handling for explicit checkpoint component files. The added tests cover both newly accepted input forms. CI is green.

Reviewed by OpenClaw 2026.6.8 (844f405)
Authored by OpenClaw (model: custom-chat-jinzhezeng-group/gpt-5.5)

[njzjz]

LGTM