M11.4: Lottie export/import

New crate effectcraft-lottie (L3): export a comp to Lottie JSON / dotLottie
(precomp and base64 image assets; shape, solid, null, precomp, image and text
layers or glyph shapes; transforms with parenting, separated position,
anchor; keyframes with speed/influence converted to normalised i/o tangents,
hold keys, spatial ti/to; all shape items incl. gradients, dashes, trim,
repeater and path operators; masks, track mattes, blend modes, time remap,
timing, markers, optional expressions, a few Lottie effects) with a warnings
list for what Lottie cannot express, and the inverse import. Commands
file.exportLottie / file.importLottie with File > Export / Import entries.
Round-trip tests (values and rendered frames) and hand-written fixtures.

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

crates/engine/src/commands/lottie.rs

@@ -0,0 +1,67 @@
+//! File ▸ Export ▸ Lottie JSON… and File ▸ Import ▸ Lottie… (`effectcraft-lottie`).
+
+use effectcraft_lottie::{ExportOptions, ImportedImage};
+use serde_json::{Value, json};
+
+use super::{CommandSpec, always, b_p, bad, comp_id, has_comp, str_p};
+use crate::{EngineError, Result, Session, cmd};
+
+fn export_lottie(s: &mut Session, p: &Value) -> Result<Value> {
+    let path = str_p(p, "path").ok_or_else(|| bad("file.exportLottie", "missing `path`"))?.to_string();
+    let cid = comp_id(s, p)?;
+    let opts = ExportOptions { include_expressions: b_p(p, "includeExpressions").unwrap_or(false), text_as_shapes: b_p(p, "textAsShapes").unwrap_or(false) };
+    let services = s.services.clone();
+    let read = move |f: &str| services.read_file(f).ok();
+    let res = effectcraft_lottie::export_comp(&s.project, cid, &opts, &read).map_err(|e| EngineError::Other(e.to_string()))?;
+    let dot = path.to_ascii_lowercase().ends_with(".lottie");
+    let bytes = if dot {
+        let stem = std::path::Path::new(&path).file_stem().map(|n| n.to_string_lossy().to_string()).unwrap_or_default();
+        effectcraft_lottie::to_dotlottie(&res, &stem)
+    } else {
+        res.to_string_compact().into_bytes()
+    };
+    s.services.write_file(&path, &bytes).map_err(|e| EngineError::Other(format!("cannot write {path}: {e}")))?;
+    let n = res.warnings.len();
+    s.toast(if n == 0 { format!("Exported Lottie to {path}") } else { format!("Exported Lottie to {path} ({n} warning{})", if n == 1 { "" } else { "s" }) });
+    Ok(json!({"path": path, "bytes": bytes.len(), "warnings": res.warnings}))
+}
+
+fn import_lottie(s: &mut Session, p: &Value) -> Result<Value> {
+    let path = str_p(p, "path").ok_or_else(|| bad("file.importLottie", "missing `path`"))?.to_string();
+    let bytes = s.services.read_file(&path).map_err(|e| EngineError::Other(format!("cannot read {path}: {e}")))?;
+    let fp = std::path::Path::new(&path);
+    let dir = fp.parent().map(|d| d.to_string_lossy().to_string()).unwrap_or_default();
+    let stem = fp.file_stem().map(|n| n.to_string_lossy().to_string()).unwrap_or_else(|| "Lottie".into());
+    let services = s.services.clone();
+    // Embedded images are written next to the Lottie file (`<name>_<asset id>.<ext>`).
+    let mut store = |img: &ImportedImage| -> Option<String> {
+        let safe: String = img.id.chars().map(|c| if c.is_ascii_alphanumeric() || c == '_' || c == '-' { c } else { '_' }).collect();
+        let file = std::path::Path::new(&dir).join(format!("{stem}_{safe}.{}", img.ext)).to_string_lossy().to_string();
+        services.write_file(&file, &img.bytes).ok().map(|_| file)
+    };
+    let res = s.edit("Import Lottie", None, |proj, st| {
+        let r = effectcraft_lottie::import(proj, &bytes, &stem, &dir, &mut store).map_err(|e| EngineError::Other(e.to_string()))?;
+        st.project_selection = vec![r.comp];
+        Ok(r)
+    })?;
+    s.open_comp(res.comp);
+    if !res.warnings.is_empty() {
+        s.toast(format!("Imported {path} ({} warnings)", res.warnings.len()));
+    }
+    Ok(json!({"comp": res.comp.0, "items": res.items.iter().map(|i| i.0).collect::<Vec<_>>(), "warnings": res.warnings}))
+}
+
+pub fn specs() -> Vec<CommandSpec> {
+    vec![
+        cmd!(
+            "file.exportLottie",
+            "Lottie JSON...",
+            ["File", "Export"],
+            None,
+            "{comp?, path (.json or .lottie), includeExpressions?: bool, textAsShapes?: bool}",
+            has_comp,
+            export_lottie
+        ),
+        cmd!("file.importLottie", "Lottie...", ["File", "Import"], None, "{path (.json or .lottie)}", always, import_lottie),
+    ]
+}

crates/engine/src/commands/mod.rs

@@ -15,6 +15,7 @@ mod layer;
 mod layer_menu;
 mod layer_time;
 mod link;
+mod lottie;
 mod mask;
 mod prop;
 mod query;
@@ -100,6 +101,7 @@ pub fn command_specs() -> &'static [CommandSpec] {
         v.extend(animation::specs());
         v.extend(view::specs());
         v.extend(file_more::specs());
+        v.extend(lottie::specs());
         v.extend(comp_more::specs());
         v.extend(frontend::specs());
         v.extend(stubs::specs());