Fix #526: the exports and the CLI write .ai as Save As does

file.saveAs and document.save wrote a PDF-compatible .ai, but
document.export (and with it the CLI's run --export x.ai and convert
in.svg out.ai, and MCP's export) refused it as a format that can only be
opened, and --help didn't list it as writable.

The .ai encoder is now shared: save.rs's ai_params and encode_ai (a PDF
of every artboard with the PDF options, carrying the native document,
blank pages with pdfCompatible: false) serve Save As and the exports
alike. The .ai format is writable, so document.formats, --help and the
MCP export tool list it; an export leaves the document's own path alone.
Export As and Export for Screens keep leaving .ai to Save As.

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

crates/engine/src/cmd/fileio/encode.rs

@@ -417,6 +417,12 @@ fn encode_files(doc: &Document, f: &Format, p: &Value) -> Result<Encoded> {
         "txt" => super::text::encode(doc, p)?,
         "svg" | "svgz" => return super::svg::encode(doc, p, f.id == "svgz").map_err(|e| bad(C, e)),
         "dxf" => return super::dxf::encode(doc, p, use_artboards),
+        // As Save As writes it (a PDF of every artboard carrying the native document).
+        "ai" => {
+            let mut q = p.clone();
+            super::save::ai_params(&mut q);
+            return super::save::encode_ai(C, f, doc, &q);
+        }
         // EPS reads its own `useArtboards` (the art's bounds unless asked).
         "eps" => return super::eps::encode(doc, p),
         "emf" => return super::metafile::encode(doc, p, use_artboards, vectorcraft_metafile::Kind::Emf),

crates/engine/src/cmd/fileio/mod.rs

@@ -465,8 +465,8 @@ pub const FORMATS: &[Format] = &[
         extensions: &["ai"],
         mime: "application/pdf",
         read: true,
-        // Saved (Save As), not exported.
-        write: false,
+        // Save As writes it; exports write the same file.
+        write: true,
         raster: false,
         options: native::AI_OPTIONS,
     },

crates/engine/src/cmd/fileio/save.rs

@@ -305,6 +305,35 @@ fn blank_pages(doc: &Document) -> Document {
 /// Why a `.ai` file saved without PDF content looks empty elsewhere.
 const NOT_PDF_COMPATIBLE: &str = "saved without PDF content: VectorCraft opens it as before, other apps show empty pages";
 
+/// The encoder's params for a `.ai` file, from a save's or an export's: a PDF of every artboard
+/// with the PDF options, always carrying the native document; Use Compression compresses the
+/// PDF's content.
+pub(super) fn ai_params(params: &mut Value) {
+    let Some(o) = params.as_object_mut() else { return };
+    o.extend([("preserveEditing".into(), json!(true)), ("range".into(), json!("all"))]);
+    if let Some(c) = o.get("compress").and_then(Value::as_bool) {
+        let compression = o.entry("compression").or_insert_with(|| json!({}));
+        if let Some(m) = compression.as_object_mut() {
+            m.insert("compressText".into(), json!(c));
+        }
+    }
+}
+
+/// Encode `doc` as a PDF-compatible `.ai` file (`params` as [`ai_params`] makes them) for command
+/// `cmd`: its pages (blank with `pdfCompatible: false`, which it then notes), carrying the native
+/// document. File › Save As writes it, and so do the exports (`document.export`, the CLI).
+pub(super) fn encode_ai(cmd: &str, f: &Format, doc: &Document, params: &Value) -> Result<Encoded> {
+    let compatible = bool_or(params, "pdfCompatible", true);
+    let pages = doc.without_edit_modes();
+    let pages = if compatible { pages } else { std::borrow::Cow::Owned(blank_pages(&pages)) };
+    let native = || super::native::ai_native(cmd, f, doc, params);
+    let (bytes, mut warnings) = super::pdf::encode_carrying(cmd, &pages, params, native)?;
+    if !compatible {
+        warnings.insert(0, NOT_PDF_COMPATIBLE.to_string());
+    }
+    Ok(Encoded { warnings, ..Encoded::one(bytes) })
+}
+
 /// Snapshot the active document for `plan` (stamping File Info's dates when the file becomes the
 /// document's own). Bad options fail here, before anything is encoded.
 pub fn save_job(s: &mut Session, plan: SavePlan) -> Result<SaveJob> {
@@ -339,16 +368,8 @@ pub(crate) fn job_for(s: &Session, st: &DocState, plan: SavePlan) -> Result<Save
     }
     let boards = separate_boards(cmd, plan.format, &doc, &params)?;
     let mut params = super::pdf::expand_preset(s, cmd, &params)?.into_owned();
-    if let (Some(o), "ai") = (params.as_object_mut(), plan.format.id) {
-        // A PDF of every artboard with the PDF options, always carrying the native document.
-        o.extend([("preserveEditing".into(), json!(true)), ("range".into(), json!("all"))]);
-        // Use Compression compresses the PDF's content.
-        if let Some(c) = o.get("compress").and_then(Value::as_bool) {
-            let compression = o.entry("compression").or_insert_with(|| json!({}));
-            if let Some(m) = compression.as_object_mut() {
-                m.insert("compressText".into(), json!(c));
-            }
-        }
+    if plan.format.id == "ai" {
+        ai_params(&mut params);
     }
     Ok(SaveJob { plan, doc, params, snapshot: st.doc.clone(), boards })
 }
@@ -372,25 +393,14 @@ impl SaveJob {
             let one = self.encode_one(&artboard_doc(&self.doc, b))?;
             enc.files.extend(one.files.into_iter().map(|(_, bytes)| (Some(b), bytes)));
         }
-        let pdf_less = self.plan.format.id == "ai" && !bool_or(&self.params, "pdfCompatible", true);
-        let notes = fidelity_warning(self.plan.format).into_iter().chain(pdf_less.then(|| NOT_PDF_COMPATIBLE.to_string()));
-        enc.warnings.splice(0..0, notes);
+        enc.warnings.splice(0..0, fidelity_warning(self.plan.format));
         Ok(enc)
     }
 
     /// Encode one file of `doc` in the job's format.
     fn encode_one(&self, doc: &Document) -> Result<Encoded> {
         let (cmd, f) = (self.plan.mode.command(), self.plan.format);
-        let enc = if f.id == "ai" {
-            // The pages (blank without PDF content), carrying the native document.
-            let pages = doc.without_edit_modes();
-            let pages = if bool_or(&self.params, "pdfCompatible", true) { pages } else { std::borrow::Cow::Owned(blank_pages(&pages)) };
-            let native = || super::native::ai_native(cmd, f, doc, &self.params);
-            let (bytes, warnings) = super::pdf::encode_carrying(cmd, &pages, &self.params, native)?;
-            Encoded { warnings, ..Encoded::one(bytes) }
-        } else {
-            encode_all(doc, f.id, &self.params)?
-        };
+        let enc = if f.id == "ai" { encode_ai(cmd, f, doc, &self.params)? } else { encode_all(doc, f.id, &self.params)? };
         if enc.files.len() != 1 {
             return Err(bad(cmd, "Save writes one artboard: name one, or export several with document.export"));
         }

crates/engine/src/cmd/fileio/screens.rs

@@ -161,7 +161,7 @@ impl Row {
             return Err(bad(C, "each format is an object {format, scale?, suffix?}"));
         }
         let format = writable(C, Some(str_param(row, "format").unwrap_or("png")), None)?;
-        if matches!(format.id, "vectorcraft" | "template" | "txt" | "dxf" | "eps" | "emf" | "wmf") {
+        if matches!(format.id, "vectorcraft" | "template" | "ai" | "txt" | "dxf" | "eps" | "emf" | "wmf") {
             return Err(bad(C, "Export for Screens writes png, png8, jpg, webp, gif, svg, svgz or pdf"));
         }
         // Vector formats have no pixel size: it doesn't apply and adds no @2x suffix (not even one

crates/engine/src/cmd/fileio/tests.rs

@@ -173,6 +173,7 @@ fn export_extensions_name_every_writable_format() {
             "svg",
             "svgz",
             "pdf",
+            "ai",
             "png",
             "jpg",
             "gif",
@@ -206,6 +207,7 @@ fn formats_query_lists_readers_writers_and_options() {
             "svg",
             "svgz",
             "pdf",
+            "ai",
             "png",
             "jpg",
             "gif",

crates/engine/src/cmd/fileio/tests_pdfedit.rs

@@ -118,6 +118,27 @@ fn ai_files_are_pdfs_that_save_and_reopen_editable() {
     assert_eq!(s.doc().unwrap().path, None);
 }
 
+/// #526: the exports (`document.export`, the CLI's `--export` and `convert`) write `.ai` as Save
+/// As does, leaving the document's own path alone.
+#[test]
+fn exports_write_ai_as_save_as_does() {
+    let mut s = rich();
+    let before = comparable(&s.doc().unwrap().doc);
+    let path = tmp("exported.ai");
+    let r = s.execute("document.export", &json!({"path": path})).unwrap();
+    assert_eq!(r["format"], "ai", "{r}");
+    let bytes = std::fs::read(&path).unwrap();
+    assert!(bytes.starts_with(b"%PDF") && vectorcraft_pdf::editing(&bytes).is_some_and(|e| e.intact), "PDF-compatible, carrying the document");
+    assert_eq!(s.doc().unwrap().path, None, "an export doesn't give the document a path");
+    let r = s.execute("document.open", &json!({"path": path})).unwrap();
+    assert_eq!((&r["format"], &r["restored"]), (&json!("ai"), &json!(true)), "{r}");
+    assert_eq!(comparable(&s.doc().unwrap().doc), before);
+    // Its options as Save As takes them; no path gives the bytes.
+    let r = s.execute("document.export", &json!({"format": "ai", "pdfCompatible": false})).unwrap();
+    assert!(r["warnings"].as_array().unwrap().iter().any(|w| w.as_str().is_some_and(|w| w.contains("without PDF content"))), "{r}");
+    assert!(b64(&r).starts_with(b"%PDF"));
+}
+
 #[test]
 fn ait_templates_open_their_document_untitled() {
     let mut s = rich();