Merge PR #1193

# Conflicts:
#	docs/parity-checklist.md

crates/engine/src/cmd/xmp.rs

@@ -49,6 +49,10 @@ fn read(s: &mut Session, p: &Value) -> Result<Value> {
     }
     if !ops.is_empty() {
         s.commit("Read Metadata from File", Op::Batch { ops })?;
+        // Don't auto-write the sidecars just read: that would add our `lc:settings` to one that had
+        // only another app's `crs:` settings, and later reads prefer `lc:settings`, so that app's
+        // next edits would be ignored (issue #934). The next edit, or Save Metadata, writes them.
+        s.skip_auto_write = true;
     }
     let mut result = json!({"read": read, "failed": failed});
     if !warnings.is_empty() {
@@ -90,7 +94,7 @@ pub fn specs() -> Vec<CommandSpec> {
             "Read Metadata from File",
             ["Photo"],
             None,
-            "{ids?} — reads each photo's XMP sidecar (or a raw/DNG's embedded XMP): metadata and develop settings, one undo step → {read, failed, warnings?: [{path, code, profile?, mode?, fields?}]}",
+            "{ids?} — reads each photo's XMP sidecar (or a raw/DNG's embedded XMP): metadata and develop settings, one undo step; never writes the sidecar, even with auto-write on → {read, failed, warnings?: [{path, code, profile?, mode?, fields?}]}",
             has_selection,
             read
         ),

crates/engine/src/tests_xmp.rs

@@ -195,6 +195,71 @@ fn foreign_crs_sidecar_on_import_and_read_from_file() {
     let _ = std::fs::remove_dir_all(&src);
 }
 
+/// A sidecar with only `crs:` develop settings, as LRTimelapse writes them (issue #934).
+fn crs_exposure_sidecar(exposure: &str) -> String {
+    format!(
+        r#"<x:xmpmeta xmlns:x="adobe:ns:meta/"><rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"><rdf:Description rdf:about="" xmlns:crs="http://ns.adobe.com/camera-raw-settings/1.0/" crs:Version="15.0" crs:Exposure2012="{exposure}"/></rdf:RDF></x:xmpmeta>"#
+    )
+}
+
+/// Issue #934: with auto-write on, Read Metadata from File wrote what it had just read straight back
+/// into the sidecar, adding our `lc:settings`. Reading leaves the file byte for byte; an edit made
+/// after it is still written.
+#[test]
+fn reading_metadata_leaves_the_sidecar_alone_with_auto_write_on() {
+    let src = temp_dir("read-no-autowrite");
+    write_png(&src.join("frame.png"), 6);
+    let sidecar = src.join("frame.xmp");
+    std::fs::write(&sidecar, crs_exposure_sidecar("0.5")).unwrap();
+    let mut s = Session::new().with_fs();
+    s.execute("library.import", &json!({"paths": [src.to_string_lossy()]})).unwrap();
+    let id = only(&s);
+    assert_eq!(s.catalog.photo(id).unwrap().develop.light.exposure, 0.5);
+    // something for the read to change back (auto-write is still off, so the file stays as it is)
+    s.execute("develop.reset", &json!({"ids": [id.0]})).unwrap();
+    s.execute("library.xmpPreferences", &json!({"autoWrite": true})).unwrap();
+    let before = std::fs::read(&sidecar).unwrap();
+    let r = s.execute("photo.readMetadataFromFile", &json!({"ids": [id.0]})).unwrap();
+    assert_eq!(r["read"].as_array().unwrap().len(), 1, "{r}");
+    assert_eq!(s.catalog.photo(id).unwrap().develop.light.exposure, 0.5, "the sidecar was read");
+    let now = std::fs::read(&sidecar).unwrap();
+    assert!(now == before, "reading leaves the sidecar byte for byte, but it is now:\n{}", String::from_utf8_lossy(&now));
+    // a develop edit afterwards is still written (only the read is exempt)
+    s.execute("develop.set", &json!({"ids": [id.0], "control": "light.exposure", "value": 0.9})).unwrap();
+    let after = std::fs::read_to_string(&sidecar).unwrap();
+    match crate::sidecar::parse_sidecar(&after, crate::crs::Target::Rendered).unwrap().develop {
+        Some(crate::sidecar::DevelopPatch::Full(d)) => assert_eq!(d.light.exposure, 0.9),
+        other => panic!("the edit wasn't auto-written: {other:?}\n{after}"),
+    }
+    assert!(after.contains(r#"crs:Exposure2012="0.5""#), "the other app's settings are kept: {after}");
+    let _ = std::fs::remove_dir_all(&src);
+}
+
+/// Issue #934, the round trip the write-back broke: after a read with auto-write on, another app
+/// changes `crs:Exposure2012` from 0.5 to 1.2 (keeping the rest of the file), and the next read
+/// takes 1.2.
+#[test]
+fn a_crs_change_after_a_read_is_taken_with_auto_write_on() {
+    let src = temp_dir("read-then-crs-change");
+    write_png(&src.join("frame.png"), 7);
+    let sidecar = src.join("frame.xmp");
+    std::fs::write(&sidecar, crs_exposure_sidecar("0.5")).unwrap();
+    let mut s = Session::new().with_fs();
+    s.execute("library.import", &json!({"paths": [src.to_string_lossy()]})).unwrap();
+    let id = only(&s);
+    s.execute("library.xmpPreferences", &json!({"autoWrite": true})).unwrap();
+    s.execute("photo.readMetadataFromFile", &json!({"ids": [id.0]})).unwrap();
+    assert_eq!(s.catalog.photo(id).unwrap().develop.light.exposure, 0.5);
+    // the other app edits the file as it is now
+    let text = std::fs::read_to_string(&sidecar).unwrap();
+    let changed = text.replace(r#"crs:Exposure2012="0.5""#, r#"crs:Exposure2012="1.2""#);
+    assert_ne!(changed, text);
+    std::fs::write(&sidecar, changed).unwrap();
+    s.execute("photo.readMetadataFromFile", &json!({"ids": [id.0]})).unwrap();
+    assert_eq!(s.catalog.photo(id).unwrap().develop.light.exposure, 1.2, "the second read takes the other app's exposure");
+    let _ = std::fs::remove_dir_all(&src);
+}
+
 /// Lightroom's default profiles (`Adobe Standard`, `Adobe Color`) are named by nearly every sidecar
 /// and our own starting look stands in for them: importing one gives no camera-profile warning.
 #[test]

docs/parity-checklist.md

@@ -167,7 +167,7 @@ differences and missing bindings are in [ui-parity.md](ui-parity.md#shortcuts).
 | LR-META-COPYRIGHT-DEFAULT | Default copyright on import | P1 | ✅ | `cmd:library.preferences` (`import.copyright`, `import.creator`), `crates/ui-egui/src/panels/settings.rs` | Settings → Import → Metadata; fills only photos without their own |
 | LR-META-LOCATION | Location editing | P2 | 🟡 | `cmd:photo.setMeta` (`location`, `city`, `state`, `country`, `gps`), `cmd:metadata.reverseGeocode` | place fields and GPS (decimal or degrees / minutes / seconds) edited in Info, read/written as IPTC Core / Photoshop / EXIF XMP; Show on Map opens OpenStreetMap; Fill Location fills empty City / State / Country from GPS offline (GeoNames, downloaded on request: `cmd:metadata.downloadPlaceNames`); no embedded map |
 | LR-META-COPYPASTE | Copy / paste metadata | P2 | ✅ | `cmd:photo.copyMetadata`, `cmd:photo.pasteMetadata` | title, caption, alt text, extended description, copyright (notice, status, usage terms, info URL), creator, place fields, keywords; `fields` picks a subset |
-| LR-META-XMP | XMP read/write | P0 | ✅ | `cmd:photo.saveMetadataToFile`, `cmd:photo.readMetadataFromFile`, `cmd:library.xmpPreferences`, `crates/engine/src/sidecar.rs`, `docs/xmp-interop.md` | sidecar wins for metadata; a sidecar capture time (`exif:DateTimeOriginal` / `photoshop:DateCreated` / `xmp:CreateDate`) fills in only when the file has none; saving merges into an existing sidecar (`crates/meta/src/xmp_merge.rs`): another app's `crs:`, `xmpMM:History` and unknown namespaces are kept byte for byte, an unreadable sidecar is backed up first; with stem naming, files sharing a stem (raw + JPEG) get separate sidecars (`<file>.xmp` for all but the raw); a `crs:` custom white balance on a relative-WB raw is shifted from `crs:AsShotTemperature` rather than read as Kelvin, or kept As Shot and reported when the packet has no as-shot white (issue #510); heal and clone spots (`crs:RetouchAreas`, legacy `crs:RetouchInfo`) are read into our spots (`crates/engine/src/crs_masks.rs`, see `docs/xmp-interop.md` → Spot removal) |
+| LR-META-XMP | XMP read/write | P0 | ✅ | `cmd:photo.saveMetadataToFile`, `cmd:photo.readMetadataFromFile`, `cmd:library.xmpPreferences`, `crates/engine/src/sidecar.rs`, `docs/xmp-interop.md` | sidecar wins for metadata; a sidecar capture time (`exif:DateTimeOriginal` / `photoshop:DateCreated` / `xmp:CreateDate`) fills in only when the file has none; saving merges into an existing sidecar (`crates/meta/src/xmp_merge.rs`): another app's `crs:`, `xmpMM:History` and unknown namespaces are kept byte for byte, an unreadable sidecar is backed up first; with stem naming, files sharing a stem (raw + JPEG) get separate sidecars (`<file>.xmp` for all but the raw); a `crs:` custom white balance on a relative-WB raw is shifted from `crs:AsShotTemperature` rather than read as Kelvin, or kept As Shot and reported when the packet has no as-shot white (issue #510); heal and clone spots (`crs:RetouchAreas`, legacy `crs:RetouchInfo`) are read into our spots (`crates/engine/src/crs_masks.rs`, see `docs/xmp-interop.md` → Spot removal); Read Metadata from File never writes the sidecar back, even with auto-write on, so another app's later `crs:` edits are still read (issue #934) |
 | LR-META-EXIF-FULL | Full EXIF/IPTC [Classic] | P1 | ✅ | `cmd:photo.allMetadata`, `cmd:dialog.allMetadata`, `crates/meta/src/tags.rs`, `crates/meta/src/exif.rs`, `crates/meta/src/iptc.rs` | read and written on export; Info ▸ All Metadata…: every TIFF / EXIF / GPS / interop tag (named, common values spelled out) and the XMP fields, searchable; metadata presets |
 
 ## F. Edit panel — global adjustments (EDIT)
@@ -788,6 +788,7 @@ Latin stays upright. Advanced Japanese composition remains open. Regression cove
 | Date | Change | Summary |
 |---|---|---|
 | 2026-10-11 | minor | LR-MERGE-HDR: HDR and panorama merges of raws without colour matrices (CR2, NEF, ARW…) write the colour they open with as DNG tags (issue #965); status unchanged |
+| 2026-10-12 | minor | LR-META-XMP: Read Metadata from File no longer auto-writes the sidecar it has just read, which added `lc:settings` and hid another app's later `crs:` edits (#934); status unchanged (✅) |
 | 2026-10-11 | minor | KEY-SLIDER-TYPE: honor immediate Return/Escape and keep typed keys in the value editor; add regression references |
 | 2026-10-11 | minor | LR-PROF-CAMERACOLOR: raws with a black-and-white camera JPEG take its tone curve (issue #577) |
 | 2026-10-11 | minor | LR-VIEW-ZOOM and LR-VIEW-COMPARE: Compare and Reference are sharp at 1:1 (zoom windows per pane, two originals kept decoded while they are open); statuses unchanged |

docs/xmp-interop.md

@@ -10,7 +10,7 @@ other tools), and let LightCraft pick up edits made elsewhere.
 |---|---|
 | Name | `<stem>.xmp` by default (`IMG_0001.CR3` → `IMG_0001.xmp`); `<file>.xmp` (`IMG_0001.CR3.xmp`) with `naming: "full"`. Reading accepts either (preferred first) and `.XMP`. With stem naming, files sharing a stem don't share a sidecar: see *Shared names* below. |
 | Write | `photo.saveMetadataToFile {ids?}` (Photo ▸ Save Metadata to File, ⌘S), or automatically after every change with `library.xmpPreferences {autoWrite: true}` (File ▸ Automatically Write Changes into XMP). Slider drags are written once, when the drag ends; undo/redo rewrite the sidecar. An existing sidecar is **merged into, never replaced** (see *Saving into an existing sidecar*). Written atomically (temp file, fsync, rename). The result lists `written`, `merged` and `backups`. |
-| Read | On import (`library.import`, the report counts `sidecars`), and `photo.readMetadataFromFile {ids?}` (one undo step). For raw/DNG files without a sidecar, the XMP embedded in the file is used. |
+| Read | On import (`library.import`, the report counts `sidecars`), and `photo.readMetadataFromFile {ids?}` (one undo step). For raw/DNG files without a sidecar, the XMP embedded in the file is used. `photo.readMetadataFromFile` never writes the sidecar, even with auto-write on: writing back what it has just read would add `lc:settings`, which later reads prefer over another app's `crs:` edits (issue #934). |
 | Preferences | `library.xmpPreferences {autoWrite?, naming?: stem\|full}`, stored in the library's `prefs.json`. |
 
 What we write (standard namespaces, so other tools can read the metadata):