Implements Phase 6.6.2 atomic file write infrastructure with temp-file-and-rename
pattern. File-backed outputs now write to a temporary file and only rename to the
target path on successful commit. If the writer is dropped without committing, the
temporary file is automatically removed.
Key changes:
- New AtomicFileWriter module with temp file generation (pid + random suffix)
- CLI extract command gains --output option (default: "-" for stdout)
- All formats (json, text, markdown) write through AtomicFileWriter
- Drop safety: temp files cleaned up on panic or early return
- Unit tests verify commit, drop cleanup, and concurrent write scenarios
Acceptance criteria:
- ✓ Critical test: panic mid-extraction → no partial output files
- ✓ Successful extraction: temp file renamed to target
- ✓ Concurrent extractions: no collision (random suffix)
- ✓ Drop cleanup: orphaned temp files removed
Closes: pdftract-68wfa
2b94f4b675