LR-PREF-DISPLAY: on Linux, previews use the display profile from colord

While no monitor profile is chosen, the Linux app reads the profile the
desktop assigns to the display in colord (org.freedesktop.ColorManager,
system bus, via zbus) on a background thread every 3 s, and shows
previews through it. With several displays it is used only when they all
share one profile; without colord the view stays sRGB. Windows' WCS
needs FFI and stays manual. Also satisfies clippy 1.99's
chunks_exact_to_as_chunks in spots.rs.

Sources: the colord D-Bus API documentation; own design.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

docs/gaps.md

@@ -1,6 +1,6 @@
 # Gaps: where LightCraft falls short of Lightroom
 
-> **Last reviewed:** 2026-10-11 · **Last updated:** 2026-10-11 · **Change:** minor (CR3 entry names the EOS R7 C-RAW fix and the refused CRX variants; CI and Windows / Linux entries note the 0.6.0 riscv64 build; camera colour: tone curve from black-and-white camera JPEGs; Compare and Reference get sharp zoom windows; gap 4 shrinks; gap 14: the HDR switch is read from crs XMP; gaps 2 and 10: EOS R5 Mark II CR3 verified) · **Target:** Adobe Lightroom Classic 15.5 / Lightroom 9.6
+> **Last reviewed:** 2026-10-11 · **Last updated:** 2026-10-12 · **Change:** minor (gap 22: Linux reads the colord display profile); previously minor (CR3 entry names the EOS R7 C-RAW fix and the refused CRX variants; CI and Windows / Linux entries note the 0.6.0 riscv64 build; camera colour: tone curve from black-and-white camera JPEGs; Compare and Reference get sharp zoom windows; gap 4 shrinks; gap 14: the HDR switch is read from crs XMP; gaps 2 and 10: EOS R5 Mark II CR3 verified) · **Target:** Adobe Lightroom Classic 15.5 / Lightroom 9.6
 
 Every known shortfall, one entry each, ranked by user impact (how many Lightroom users hit it, and
 how hard it blocks them), then by effort. **Agents pick work from the top** (the first entry nobody is
@@ -36,7 +36,7 @@ Hours are Opus 5.5 agent wall-clock hours (see [target-app-parity.md](target-app
 | 19 | **Plug-in ecosystem**: no Lightroom SDK equivalent (export / publish plug-ins, metadata plug-ins) | ⬜ | pro workflows built on plug-ins (LR/Enfuse, Jeffrey's exporters, Negative Lab Pro) | 40–80 + owner decision | [target-app-parity](target-app-parity.md#by-dimension) |
 | 20 | **Long-tail raw formats**: compressed SRW, ARQ pixel shift, IIQ, Hasselblad compression, X3F, CRW, MRW, ERF, KDC, DCR, MEF, GPR, old FinePix | raw-parity.md | small user share each | 45–85 | [raw-parity](raw-parity.md) |
 | 21 | **Localization**: 9 of 15 shipped languages partial (74–99% of catalog messages), lower-layer errors English; Hindi, Arabic, Indonesian, Korean, Vietnamese absent; no RTL or complex shaping | measured from catalogs | non-English users see mixed English | 55–90 (shipped to full); 145–255 (five new) | [localization-parity](localization-parity.md) |
-| 22 | **Pen pressure**, OS monitor profiles, follow-window colour | hardware-parity.md | brush users with tablets; multi-monitor setups | 11–22 | [hardware-parity](hardware-parity.md) |
+| 22 | **Pen pressure**, OS monitor profiles on Windows (Linux reads colord's, macOS the screen's), follow-window colour on Linux / Windows | hardware-parity.md | brush users with tablets; multi-monitor setups | 11–22 | [hardware-parity](hardware-parity.md) |
 | 23 | **Accessibility** audit with screen readers; canvas tools keyboard-reachable | LR-BEHAV-ACCESS 🟡 | blind and low-vision users | 10–20 | [ui-parity](ui-parity.md) |
 | 24 | **Brush live preview and masking feel** (#517, #518); Feather / Edge mask refinement (15.5) | issues | masking feels slower than Lightroom | 8–12 | [ui-parity](ui-parity.md) |
 | 25 | **File writes**: lossy DNG, Render to DNG; AVIF import (PSD export landed with Edit in PhotoCraft, #953) | file-format-parity.md | interchange edge cases | 21–37 | [file-format-parity](file-format-parity.md) |
@@ -72,6 +72,7 @@ Beta-blocking gaps (B) total **~230–430 h**; with the stability and platform w
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-10-12 | minor | Gap 22: Linux previews use the display profile from colord |
 | 2026-10-11 | minor | Reviewed against main after 0.6.0: CR3 entry names the CRX variants `crx.rs` still refuses and the R7 / R6 Mark II C-RAW state (decoding, not verified, so the measured numbers don't move); CI and Windows / Linux entries note the riscv64 release build (#844); R7 fix added to Closed recently. Panel docking (UI.9, #869) closes no listed gap |
 | 2026-10-11 | minor | Camera colour entry: raws with a black-and-white camera JPEG take its tone curve (#577); gap not closed |
 | 2026-10-11 | minor | Gap 4: Compare and Reference views get zoom windows per pane (1:1 was a 2,560 px render magnified); overlays and soft proofing remain, 8–15 h → 4–8 h |