Drop underscore prefix — the helper is part of confidence.py's effective
public API since spell_check.py imports and calls it directly.
Fixes reviewer concern: importing a _-prefixed name across module boundaries
contradicts Python's private-by-convention signal.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
New confidence.py module with two functions:
- apply_confidence_markers(): replaces words below threshold with
[unleserlich], collapses adjacent markers into one
- words_from_characters(): reconstructs word-level confidence from
Kraken's character-level data
Surya 0.17 provides native word-level confidence via line.words.
Kraken 7.0 provides per-character confidences via record.confidences.
Both engines now pass word+confidence data through main.py, which
applies the marker post-processing before returning the API response.
Threshold configurable via OCR_CONFIDENCE_THRESHOLD env var (default 0.3).
Frontend already renders [unleserlich] markers via transcriptionMarkers.ts.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
