Append video name to output path when video_index is specified

[gitttt-1234]

Summary

Fixes an issue where running inference with video_index on multiple videos from the same .slp file would overwrite the output file. The output path now includes the video name to create unique filenames for each video.

Problem

When running predictions on a multi-video .slp file using the video_index parameter:

• All predictions would save to the same output path (e.g., labels.predictions.slp)
• Running inference on different videos would overwrite previous results
• Users had to manually specify unique output_path for each video

Solution

When video_index is provided and output_path is None:

• Extract the video filename from output.videos[video_index]
• Append the video name (stem) to the output path
• Format: <labels_file>.<video_name>.predictions.slp
• Falls back to video_{index} if filename is not a simple string

Example

Before:

run_inference(data_path="labels.slp", video_index=0)  # → labels.predictions.slp
run_inference(data_path="labels.slp", video_index=1)  # → labels.predictions.slp (overwrites!)

After:

run_inference(data_path="labels.slp", video_index=0)  # video1.mp4 → labels.video1.predictions.slp
run_inference(data_path="labels.slp", video_index=1)  # video2.mp4 → labels.video2.predictions.slp

Changes

• Modified run_inference() in sleap_nn/predict.py to append video name when video_index is specified
• Added test_video_index_output_path() test to verify the behavior

Testing

• New test verifies video name is included in output path when using video_index
• Existing tests continue to pass (no breaking changes)
• Behavior unchanged when video_index is None or output_path is explicitly provided

🤖 Generated with Claude Code

Co-Authored-By: Claude [email protected]

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.83%. Comparing base (ff91433) to head (d4a8e26).
⚠️ Report is 68 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #378      +/-   ##
==========================================
- Coverage   95.28%   93.83%   -1.46%     
==========================================
  Files          49       49              
  Lines        6765     7185     +420     
==========================================
+ Hits         6446     6742     +296     
- Misses        319      443     +124     

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