Film negative conversion: non-destructive & in-library (replaces the modal/TIFF flow)

[SandeepSubba]

Summary

Reworks the Film Negative Converter from a modal that bakes a separate _Positive.tiff into a non-destructive, in-library conversion that fits RapidRAW's sidecar model.

You right-click a negative → Convert Negative. It inverts to a neutral positive in place (no new file, no duplicate library entry), and you do all the tuning — exposure, white balance, contrast, curves, masks — in the normal Develop module on top. Right-click → Revert to Negative turns it back off.

Why

The old flow was self-contained because it was destructive: once you exported the TIFF there was no going back, so the modal carried its own exposure / contrast / white-balance sliders. Those duplicate what Develop already does. The only genuinely negative-specific step is the density inversion + per-channel auto-bounds — everything else belongs in Develop. Making it non-destructive removes the duplication and the duplicate files, and makes the conversion re-tunable and reversible.

What changed

Behaviour

• Right-click Convert Negative / Revert to Negative in both the editor and the library/filmstrip context menus. The label toggles based on whether the image(s) are already converted; batch selection works.
• The conversion (density inversion + per-channel auto-bounds) is stored in the image's .rrdata sidecar as negativeConversion: { enabled, bounds } and applied on load, so the editor, thumbnails and export all render the positive. The original raw is never touched.
• The Convert Negative modal is removed.

Backend

• Replaces preview_negative_conversion / convert_negatives with a single set_negative_conversion(paths, enabled).
• maybe_apply_negative inverts a flagged negative at the single decode chokepoint (load_base_image_from_bytes), so every consumer agrees.
• Auto-bounds are still computed at convert time (same NegPy-derived analysis) for a good neutral starting point.
• Adjustment saves preserve the backend-owned negativeConversion block, so a normal edit or navigation can't strip it; thumbnails regenerate on convert/revert.

Notes

• Backward compatible — existing sidecar conversions still render.
• The inversion math is unchanged (still the NegPy-derived pipeline, GPL-3.0, credited as before).

🤖 Generated with Claude Code

[CyberTimon]

Great PR!

My notes from a quick testing:

• Batch negative conversion works but batch reverting doesn't do anything
• Too many AI generated code comments. Please remove these code comments.

Thanks a lot, looks good otherwise :)