Faces: resize a face box with eight drag handles

Hovering a box shows handles at its corners and edge midpoints; dragging one
previews the new box live and commits once on release, as one undo step, through
the new `photo.setRegion {id?, index, rect}`: catalog-only like removal, never
rewriting the sidecar, with the rectangle validated (finite numbers only,
clamped to the photo, at least 0.5 % each way) and a test with a real sidecar.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

crates/engine/src/cmd/library.rs

@@ -472,6 +472,40 @@ pub fn specs() -> Vec<CommandSpec> {
                 Ok(json!({"removed": gone.name}))
             }
         ),
+        cmd!(
+            "photo.setRegion",
+            "Resize Face Box",
+            [],
+            None,
+            "{id?, index, rect: {x0, y0, x1, y1}} — set one face / pet region's box (normalized, in the photo's upright frame; clamped to the photo, at least 0.5 % each way) in the catalog; undoable. Like photo.removeRegion it never rewrites the XMP sidecar",
+            always,
+            |s, p| {
+                const C: &str = "photo.setRegion";
+                // a drag is one undo step however many frames it took: the caller commits once, on release
+                let id = p.get("id").and_then(Value::as_u64).map(PhotoId).or_else(|| s.active()).ok_or_else(|| bad(C, "no photo"))?;
+                let index = p
+                    .get("index")
+                    .and_then(Value::as_u64)
+                    .and_then(|i| usize::try_from(i).ok())
+                    .ok_or_else(|| bad(C, "missing or invalid `index`"))?;
+                let r = p.get("rect").ok_or_else(|| bad(C, "missing `rect`"))?;
+                let num = |k: &str| {
+                    r.get(k).and_then(Value::as_f64).filter(|v| v.is_finite()).ok_or_else(|| bad(C, format!("`rect.{k}` must be a finite number")))
+                };
+                let (a, b, c, d) = (num("x0")?, num("y0")?, num("x1")?, num("y1")?);
+                let (x0, x1) = (a.min(c).clamp(0.0, 1.0), a.max(c).clamp(0.0, 1.0));
+                let (y0, y1) = (b.min(d).clamp(0.0, 1.0), b.max(d).clamp(0.0, 1.0));
+                if x1 - x0 < 0.005 || y1 - y0 < 0.005 {
+                    return Err(bad(C, "the box would be too small"));
+                }
+                let mut meta = s.catalog.photo(id).ok_or_else(|| bad(C, "no such photo"))?.meta.clone();
+                let region = meta.regions.get_mut(index).ok_or_else(|| bad(C, "no such region"))?;
+                region.rect = lightcraft_geom::Rect { x0, y0, x1, y1 };
+                s.commit("Resize Face Box", Op::SetMeta { id, meta: Box::new(meta) })?;
+                s.skip_auto_write = true;
+                Ok(json!({"rect": {"x0": x0, "y0": y0, "x1": x1, "y1": y1}}))
+            }
+        ),
         // ---- delete / restore
         cmd!("photo.delete", "Delete Photo", ["Photo"], Some("Delete"), "{ids?} — moves to Recently Deleted", has_selection, |s, p| {
             let v = for_targets(s, p, "Delete", |id| Some(Op::SetDeleted { id, deleted: true }))?;

crates/engine/src/tests_xmp.rs

@@ -248,6 +248,44 @@ fn removing_a_region_is_undoable_and_leaves_the_sidecar_alone() {
     let _ = std::fs::remove_dir_all(&src);
 }
 
+/// Resizing a face box is a catalog-only, undoable edit with strict input handling; it leaves the
+/// sidecar alone like removal does.
+#[test]
+fn resizing_a_region_validates_clamps_undoes_and_leaves_the_sidecar_alone() {
+    let src = temp_dir("region-resize");
+    write_png(&src.join("portrait.png"), 9);
+    std::fs::write(src.join("portrait.xmp"), MWG_REGIONS).unwrap();
+    let mut s = Session::new().with_fs();
+    s.execute("library.import", &json!({"paths": [src.to_string_lossy()]})).unwrap();
+    let id = s.active().unwrap();
+    s.execute("library.xmpPreferences", &json!({"autoWrite": true})).unwrap();
+    let before = std::fs::read(src.join("portrait.xmp")).unwrap();
+    let original = s.catalog.photo(id).unwrap().meta.regions[0].rect;
+    let set = |s: &mut Session, rect: serde_json::Value| s.execute("photo.setRegion", &json!({"index": 0, "rect": rect}));
+    // hostile input is an error and changes nothing
+    for bad in [
+        json!({"x0": 0.1, "y0": 0.1, "x1": 0.1, "y1": 0.5}),
+        json!({"x0": 0.1, "y0": 0.1, "x1": 0.1001, "y1": 0.5}),
+        json!({"x0": 0.1, "y0": 0.1, "x1": 0.5}),
+        json!({"x0": "a", "y0": 0.1, "x1": 0.5, "y1": 0.5}),
+        json!({"x0": null, "y0": 0.1, "x1": 0.5, "y1": 0.5}),
+    ] {
+        assert!(set(&mut s, bad.clone()).is_err(), "{bad}");
+    }
+    assert!(s.execute("photo.setRegion", &json!({"index": 9, "rect": {"x0": 0.1, "y0": 0.1, "x1": 0.5, "y1": 0.5}})).is_err(), "no such region");
+    assert!(s.execute("photo.setRegion", &json!({"index": 0})).is_err(), "no rect");
+    assert_eq!(s.catalog.photo(id).unwrap().meta.regions[0].rect, original);
+    // corners given in any order and outside the photo are clamped into it
+    let r = set(&mut s, json!({"x0": 0.6, "y0": 1.5, "x1": -0.2, "y1": 0.2})).unwrap();
+    assert_eq!(r["rect"], json!({"x0": 0.0, "y0": 0.2, "x1": 0.6, "y1": 1.0}));
+    let now = s.catalog.photo(id).unwrap().meta.regions[0].rect;
+    assert_eq!((now.x0, now.y0, now.x1, now.y1), (0.0, 0.2, 0.6, 1.0));
+    assert_eq!(std::fs::read(src.join("portrait.xmp")).unwrap(), before, "the sidecar is untouched");
+    s.execute("edit.undo", &json!({})).unwrap();
+    assert_eq!(s.catalog.photo(id).unwrap().meta.regions[0].rect, original);
+    let _ = std::fs::remove_dir_all(&src);
+}
+
 fn synthetic_dng(xmp: &str) -> Vec<u8> {
     synthetic_dng_with(Some(xmp), lightcraft_meta::Metadata::default())
 }