Merge PR #1235

# Conflicts:
#	docs/whats-new.md

docs/gpu-pipeline.md

@@ -273,7 +273,7 @@ the device on their first GPU render. `lightcraft_gpu::ready()` asks without blo
   developed image in ~50 ms.
 
 ## Memory (M5.6)
-A view's stages keep an uploaded source only up to 96 MB (a Preview-level source); a bigger one (the original a zoom window is cut from) is kept once, outside the views' stages, for all views of the photo (the Before and After windows and every pan share it; the Before window of a Before/After waits at first open until the After's job has handed the original over, or each would decode and upload its own copy) and given back when the app idles (issue #323: kept per view it counted against the stage budget on every tick of a drag, and not kept every new window uploaded 288 MB again).
+A view's stages keep an uploaded source only up to 96 MB (a Preview-level source); a bigger one (the original a zoom window is cut from) is kept once, outside the views' stages, for all views of the photo (the Before and After windows and every pan share it; the Before window of a Before/After waits at first open until the After's job has handed the original over, or each would decode and upload its own copy) and given back when the app idles with no zoom window on screen (a zoomed view keeps it for its next pan: a 64 MP original is 800 MB to upload again; issue #323: kept per view it counted against the stage budget on every tick of a drag, and not kept every new window uploaded 288 MB again).
 - `library.memory` reports what the engine's caches hold (decoded thumbnail / preview / full-size
   sources, rendered previews) and the GPU renderer's device buffers (allocated, of which pooled
   and retired); `ui.inspect` → `memory` adds the loupe's stage caches (CPU images, GPU buffers)

docs/whats-new.md

@@ -65,6 +65,22 @@
   instead of opening as their embedded preview. Photos imported earlier switch over with Photo ▸ Reload from Disk.
 - An uncompressed Leaf Aptus 22 MOS no longer opens as a dark, colourless picture of its sensor mosaic: it imports
   as a raw and shows its embedded preview (preview only, with the reason), as the compressed MOS files do.
+## 2026-10-12
+
+### Zoomed 64 MP raws stay decoded
+- Panning a photo zoomed to 1:1, or moving a slider while zoomed, no longer decodes the whole raw again each time on
+  high-resolution cameras such as the Sony A7R VI (64 MP). Their decoded original (~800 MB) is bigger than the
+  default cache share (768 MB), so it was evicted as soon as it was stored. The original of the photo shown in Detail
+  now stays, like its preview, until another photo or view is shown.
+- Zooming in with Before/After side by side decodes the original once: the Before side used to decode its own copy
+  beside the After's, and a window asked for again while the first was still decoding (a pan, the layout settling)
+  started yet another decode.
+- A zoomed view keeps the GPU copy of the original while it is on screen: pausing for a few seconds between pans no
+  longer frees it, which cost a re-upload of about a second on the next pan (800 MB for a 64 MP raw). It is freed
+  once you zoom out or move on.
+- The kept original no longer pushes everything else out of the cache: on a 64 MP raw it filled the cache share
+  alone, so the photo's preview and thumbnail sources and its neighbours' were decoded from the raw again on every
+  edit at 1:1, every zoom out and every step to the next photo.
 
 ## 2026-10-11