Support prompt text via stdin. e.g. LLMs can generate prompts that directly feed into mflux. (#204 )

Co-authored-by: Anthony Wu <pls-file-gh-issue@users.noreply.github.com>

2025-06-11 07:31:46 +02:00

2.6 KiB

Raw Blame History

Add stdin support for prompt input

Summary

This PR adds support for reading prompts from stdin when --prompt - is specified, following Unix/Linux conventions. This enables piping prompts from other commands, making mflux more composable in shell scripts and workflows.

Changes

Feature Implementation

Added stdin support in prompt_utils.py: When --prompt - is provided, the prompt is read from stdin
Follows Unix conventions: Uses - as the special marker for stdin input, consistent with tools like cat, grep, etc.
Proper error handling: Raises PromptFileReadError with clear message when stdin is empty
Preserves existing behavior: Regular prompts and --prompt-file continue to work as before

Code Improvements

Converted print statements to logging: Changed print() calls to logger.info() for better control over output
Improved type annotations: Changed get_effective_prompt(args: t.Any) to use proper argparse.Namespace type
Added comprehensive tests: Both unit tests and integration tests verify the functionality

Usage Examples

# Pipe prompt from echo
echo "A beautiful sunset over mountains" | mflux-generate --prompt - --model dev --steps 20

# Pipe prompt from a file
cat prompt.txt | mflux-generate --prompt - --model dev --output result.png

# Use in a pipeline
generate-prompt-script.py | mflux-generate --prompt - --model dev --metadata

Testing

Unit Tests (`tests/arg_parser/test_stdin_prompt.py`)

✅ Basic stdin parsing (--prompt - returns "-")
✅ Regular prompt still works unchanged
✅ Whitespace trimming from stdin
✅ --prompt-file takes precedence over stdin

Integration Tests (`tests/image_generation/test_stdin_prompt_integration.py`)

✅ Single-line stdin prompt generates image with correct metadata
✅ Multi-line stdin prompt is preserved correctly
✅ Empty stdin shows appropriate error message
✅ Shell piping with echo command works correctly

All tests verify that the stdin prompt is correctly captured in the output metadata when --metadata flag is used.

Technical Details

Stdin reading happens in get_effective_prompt() when args.prompt == "-"
Uses sys.stdin.read().strip() to read and clean the input
Logging messages indicate when prompt is read from stdin vs file
Error handling for IOError, OSError, and KeyboardInterrupt

Breaking Changes

None. This is a purely additive feature that doesn't affect existing functionality.

Future Considerations

This implementation could be extended to other input arguments if needed, following the same - convention for stdin input.

2.6 KiB Raw Blame History