Gap 27: CPU-GPU equivalence verified on an AMD Radeon 8060S (Vulkan, Linux)

First non-Apple GPU verification: 16 tests / 135 cases pass, 124 at
max 1 LSB, 10 bit-identical, one at max 2 LSB (0.0002% of pixels), worst
mean 0.0003 LSB. Recorded in gpu-pipeline.md, hardware-parity.md and
gaps.md. Also as_chunks in spots.rs for the newer clippy lint.

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 27: GPU equivalence verified on an AMD Radeon on Linux) · **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
@@ -41,7 +41,7 @@ Hours are Opus 5.5 agent wall-clock hours (see [target-app-parity.md](target-app
 | 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) |
 | 26 | **Performance at scale**: 85k-photo library opens in 1.7–4.7 s; 100k grid test pending; colour NR at half resolution | ROADMAP log, gpu-pipeline.md | large-catalog users | 15–30 | [target-app-parity](target-app-parity.md#by-dimension) |
-| 27 | **Windows / Linux runtime coverage**: Windows installer UI unverified on Windows (#79); GPU path proven on Apple only; the Linux riscv64 tarball (new in 0.6.0, #844) is cross-compiled and never run beyond a QEMU smoke test | ROADMAP, issues, `release.yml` | non-Mac users find bugs first | 15–30 | [hardware-parity](hardware-parity.md) |
+| 27 | **Windows / Linux runtime coverage**: Windows installer UI unverified on Windows (#79); GPU path proven on Apple and on one AMD GPU on Linux (Radeon 8060S, Vulkan); NVIDIA, Intel and DX12 unverified; the Linux riscv64 tarball (new in 0.6.0, #844) is cross-compiled and never run beyond a QEMU smoke test | ROADMAP, issues, `release.yml` | non-Mac users find bugs first | 13–27 | [hardware-parity](hardware-parity.md) |
 | 28 | **Small Classic shortcuts and keys**: rating `[` `]`, flag cycling, filter-bar keys, F1 help, panel keys (Tab, F5–F8) | [ui-parity](ui-parity.md#shortcuts) | Classic muscle memory | 4–8 | [ui-parity](ui-parity.md) |
 
 Beta-blocking gaps (B) total **~230–430 h**; with the stability and platform work they need around them,
@@ -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 27: the CPU ↔ GPU equivalence suite passes on an AMD Radeon 8060S (Vulkan, Linux), the first non-Apple GPU verified; 15–30 h → 13–27 h; gap not closed |
 | 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 |