Export: a .ait export names file.saveAsTemplate, and the CLI's convert writes the template

document.export, document.serialize, document.exportSelection and
Export for Screens rows answered "PDF-compatible .ait template files
can be opened but not written" for a .ait, although
file.saveAsTemplate writes them. The CLI's convert and run --export
call document.export, so vectorcraft-cli convert in.pdf out.ait
failed with that error.

The error now reads "PDF-compatible .ait template files are written
by file.saveAsTemplate", with a row in the 17 catalogs that translate
status messages and in bg, da, id and nl. convert and run --export
write a .ait with file.saveAsTemplate, which writes every artboard
with the .ai options. convert passes --replace-lossy and its .ai flags
on, and refuses --artboard and --range for a .ait.

Docs: docs/mcp.md, docs/target-app-parity.md.

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

@@ -115,7 +115,7 @@ pub fn specs() -> Vec<CommandSpec> {
             "Serialize Document",
             [],
             None,
-            "{format?: vectorcraft (default)|template|svg|svgz|pdf|ai|png|jpg|webp|gif|png8|txt|dxf|eps|emf|wmf|tiff|bmp|tga|psd, …the format's options (see document.formats; SVG ones also as svg: {…}), selectedOnly?: false (the selected objects alone, in their layers)} → {text, warnings} for svg (plus dataBase64, the file, when its encoding isn't UTF-8), else {dataBase64, warnings}; an SVG of several artboards also gives files: [{name, text}], linked images linked: [{name, dataBase64}]",
+            "{format?: vectorcraft (default)|template|svg|svgz|pdf|ai|png|jpg|webp|gif|png8|txt|dxf|eps|emf|wmf|tiff|bmp|tga|psd (ait, a .ait template, is written by file.saveAsTemplate), …the format's options (see document.formats; SVG ones also as svg: {…}), selectedOnly?: false (the selected objects alone, in their layers)} → {text, warnings} for svg (plus dataBase64, the file, when its encoding isn't UTF-8), else {dataBase64, warnings}; an SVG of several artboards also gives files: [{name, text}], linked images linked: [{name, dataBase64}]",
             has_doc,
             export::serialize
         ),
@@ -124,7 +124,7 @@ pub fn specs() -> Vec<CommandSpec> {
             "Export Document",
             [],
             None,
-            "{path?, format?: svg|svgz|pdf|ai|png|jpg|webp|gif|png8|txt|dxf|eps|emf|wmf|tiff|bmp|tga|psd|vectorcraft|template (default: from the path's extension, else png; png8 writes an indexed .png), selectedOnly?: false (the selected objects alone, in their layers), artboard?: 0, artboards?: [i…], rect?: [x, y, width, height] (raster formats: that area of the page in points, y down, instead of an artboard; not with artboard, artboards, range or useArtboards), range?: \"1-3, 5\" | \"all\" (1-based; PDF and .ai write one page per artboard, default all; SVG writes one file per artboard, {stem}-{artboard}.svg; raster formats write one artboard), useArtboards?: true (raster: one file per chosen artboard, default all, {stem}-{artboard}.{ext}; pdf/ai: every page) | false (pdf/ai/raster: the bounds of the visible art; SVG has it as an SVG option), ppi?: 72 (raster formats: pixels per inch, stored in the file; wins over scale), scale?: 1 (pixels per point), background?: transparent|white|black|\"#rrggbb\" (jpg: white when transparent), antiAlias?: none|art (default)|type (text snapped to pixels), interlaced?: false (png, Adam7), embedIcc?: true (png: an sRGB chunk marks the colours as sRGB), quality?: 90 (jpg: 0–100), colorModel?: rgb|cmyk|gray (jpg), method?: baseline|optimized|progressive, scans?: 3 (3–5, progressive), embedIcc?: true, imageMap?: none|client|server (an HTML or NCSA map of the objects with a URL, written as <stem>.html / <stem>.map), colors?: 256 (gif/png8: 2–256), reduction?: perceptual|selective (default)|adaptive|web|blackWhite|gray, dither?: none|diffusion (default)|pattern|noise, ditherAmount?: 100, transparency?: true, matte?: white|\"#rrggbb\"|none, interlaced?, lossless?: true (webp: lossy WebP isn't available yet: written lossless, with a warning), encoding?: utf8|utf16 (txt: the stories in stacking order, back to front, a thread once; utf16 with a byte order mark), lineEndings?: lf|crlf, selectionOnly?: false, svg?: {styling, outlineText, images, objectIds, decimals, minify, responsive, useArtboards, preserveEditing, metadata, fewerTspans, hiddenLayers, encoding, profile, embedFonts} (see document.formats), …the SVG options given flat instead, …the PDF options of document.exportPdf, …the DXF options of document.exportDxf (useArtboards: one drawing per artboard), …the EPS options of document.exportEps (useArtboards: one file per artboard, {stem}_{artboard}.eps; else the visible art), …emf and wmf write one picture of the artboard (useArtboards: true one file per chosen artboard, false the bounds of the visible art; EMF keeps curves, clipping, transparent images and gradients as images clipped to their shape; WMF flattens curves into polygons behind a placeable header; what a format leaves out comes back in warnings), colorModel?: rgb|cmyk|gray (tiff: rgb keeps transparency as an alpha channel), lzw?: true, byteOrder?: little|big, embedIcc?: true, colorModel?: rgb|gray (bmp), depth?: 24 (bmp: 1 black and white, 4|8 a palette by reduction and dither, 16, 24, 32 with alpha), fileFormat?: windows|os2 (1, 4, 8 or 24 bits), rle?: false (4 and 8 bits, windows), flipRows?: false (top-down rows), depth?: 24 (tga: 16 one-bit alpha, 24, 32 with alpha), colorModel?: rgb|cmyk|gray (psd), layers?: true (each top-level layer a pixel layer with its opacity and blend mode; a background colour is a Background layer; false: one flat image, on white), maxEditability?: false (layers and sublayers become groups, each object a layer named as in the Layers panel, text by its text; clipping, masked or knockout layers stay one layer), hiddenLayers?: false (hidden layers and objects written hidden instead of left out), embedIcc?: true (at most 30000 pixels a side; formats without alpha are flattened on white)} → {path, format, bytes, warnings, files?: [path…] (several), linked?: [path…] (linked images, image maps)}; no path → {dataBase64, format, bytes, warnings, files?: [{name, dataBase64}], linked?: [{name, dataBase64}]}. Never changes the document's path",
+            "{path?, format?: svg|svgz|pdf|ai|png|jpg|webp|gif|png8|txt|dxf|eps|emf|wmf|tiff|bmp|tga|psd|vectorcraft|template (default: from the path's extension, else png; png8 writes an indexed .png; ait, a .ait template, is written by file.saveAsTemplate), selectedOnly?: false (the selected objects alone, in their layers), artboard?: 0, artboards?: [i…], rect?: [x, y, width, height] (raster formats: that area of the page in points, y down, instead of an artboard; not with artboard, artboards, range or useArtboards), range?: \"1-3, 5\" | \"all\" (1-based; PDF and .ai write one page per artboard, default all; SVG writes one file per artboard, {stem}-{artboard}.svg; raster formats write one artboard), useArtboards?: true (raster: one file per chosen artboard, default all, {stem}-{artboard}.{ext}; pdf/ai: every page) | false (pdf/ai/raster: the bounds of the visible art; SVG has it as an SVG option), ppi?: 72 (raster formats: pixels per inch, stored in the file; wins over scale), scale?: 1 (pixels per point), background?: transparent|white|black|\"#rrggbb\" (jpg: white when transparent), antiAlias?: none|art (default)|type (text snapped to pixels), interlaced?: false (png, Adam7), embedIcc?: true (png: an sRGB chunk marks the colours as sRGB), quality?: 90 (jpg: 0–100), colorModel?: rgb|cmyk|gray (jpg), method?: baseline|optimized|progressive, scans?: 3 (3–5, progressive), embedIcc?: true, imageMap?: none|client|server (an HTML or NCSA map of the objects with a URL, written as <stem>.html / <stem>.map), colors?: 256 (gif/png8: 2–256), reduction?: perceptual|selective (default)|adaptive|web|blackWhite|gray, dither?: none|diffusion (default)|pattern|noise, ditherAmount?: 100, transparency?: true, matte?: white|\"#rrggbb\"|none, interlaced?, lossless?: true (webp: lossy WebP isn't available yet: written lossless, with a warning), encoding?: utf8|utf16 (txt: the stories in stacking order, back to front, a thread once; utf16 with a byte order mark), lineEndings?: lf|crlf, selectionOnly?: false, svg?: {styling, outlineText, images, objectIds, decimals, minify, responsive, useArtboards, preserveEditing, metadata, fewerTspans, hiddenLayers, encoding, profile, embedFonts} (see document.formats), …the SVG options given flat instead, …the PDF options of document.exportPdf, …the DXF options of document.exportDxf (useArtboards: one drawing per artboard), …the EPS options of document.exportEps (useArtboards: one file per artboard, {stem}_{artboard}.eps; else the visible art), …emf and wmf write one picture of the artboard (useArtboards: true one file per chosen artboard, false the bounds of the visible art; EMF keeps curves, clipping, transparent images and gradients as images clipped to their shape; WMF flattens curves into polygons behind a placeable header; what a format leaves out comes back in warnings), colorModel?: rgb|cmyk|gray (tiff: rgb keeps transparency as an alpha channel), lzw?: true, byteOrder?: little|big, embedIcc?: true, colorModel?: rgb|gray (bmp), depth?: 24 (bmp: 1 black and white, 4|8 a palette by reduction and dither, 16, 24, 32 with alpha), fileFormat?: windows|os2 (1, 4, 8 or 24 bits), rle?: false (4 and 8 bits, windows), flipRows?: false (top-down rows), depth?: 24 (tga: 16 one-bit alpha, 24, 32 with alpha), colorModel?: rgb|cmyk|gray (psd), layers?: true (each top-level layer a pixel layer with its opacity and blend mode; a background colour is a Background layer; false: one flat image, on white), maxEditability?: false (layers and sublayers become groups, each object a layer named as in the Layers panel, text by its text; clipping, masked or knockout layers stay one layer), hiddenLayers?: false (hidden layers and objects written hidden instead of left out), embedIcc?: true (at most 30000 pixels a side; formats without alpha are flattened on white)} → {path, format, bytes, warnings, files?: [path…] (several), linked?: [path…] (linked images, image maps)}; no path → {dataBase64, format, bytes, warnings, files?: [{name, dataBase64}], linked?: [{name, dataBase64}]}. Never changes the document's path",
             has_doc,
             export::export
         ),
@@ -813,7 +813,8 @@ pub fn format_for_name(name: &str) -> Option<&'static Format> {
     Some(extension(name)).filter(|e| !e.is_empty()).and_then(|e| format(&e))
 }
 
-/// The format to write: `format` (an id or extension), else the path's extension, else PNG.
+/// The format to write: `format` (an id or extension), else the path's extension, else PNG. For a
+/// `.ait` template it returns an error that names `file.saveAsTemplate`, which writes it.
 pub fn writable_format(format_param: Option<&str>, path: Option<&str>) -> std::result::Result<&'static Format, String> {
     // Formats that can't be written say what to use instead.
     let unknown = |what: String, key: &str| unsupported(key).map_or(what, |u| u.hint.to_string());
@@ -822,7 +823,13 @@ pub fn writable_format(format_param: Option<&str>, path: Option<&str>) -> std::r
         (None, Some(e)) => format(&e).ok_or_else(|| unknown(format!("unknown extension `.{e}`: pass `format` (see document.formats)"), &e))?,
         (None, None) => format("png").ok_or("no PNG encoder")?,
     };
-    if f.write { Ok(f) } else { Err(format!("{} files can be opened but not written (see document.formats)", f.label)) }
+    if f.write {
+        Ok(f)
+    } else if TEMPLATE_FORMATS.contains(&f.id) {
+        Err(format!("{} files are written by file.saveAsTemplate", f.label))
+    } else {
+        Err(format!("{} files can be opened but not written (see document.formats)", f.label))
+    }
 }
 
 /// [`writable_format`] for command `cmd`.

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

@@ -232,6 +232,28 @@ fn save_as_template_names_its_file_after_the_template_format() {
     }
 }
 
+/// Exports don't write a `.ait`: each export asked for one, by its path or `format`, answers an
+/// error that names `file.saveAsTemplate`, which writes it, and writes nothing. A format that
+/// nothing writes keeps its own error.
+#[test]
+fn exports_of_an_ait_name_save_as_template() {
+    let mut s = rich();
+    let path = tmp("exported.ait");
+    let _ = std::fs::remove_file(&path);
+    for (cmd, p) in [
+        ("document.export", json!({"path": path})),
+        ("document.export", json!({"format": "ait"})),
+        ("document.serialize", json!({"format": "ait"})),
+        ("document.exportSelection", json!({"path": path})),
+        ("document.exportForScreens", json!({"formats": [{"format": "ait"}]})),
+    ] {
+        let e = s.execute(cmd, &p).unwrap_err().to_string();
+        assert!(e.contains("PDF-compatible .ait template files are written by file.saveAsTemplate"), "{cmd} {p}: {e}");
+    }
+    assert!(!std::path::Path::new(&path).exists(), "nothing written");
+    assert_eq!(writable_format(Some("ps"), None).unwrap_err(), "PostScript files can be opened but not written (see document.formats)");
+}
+
 #[test]
 fn standards_and_screens_leave_the_editing_data_out() {
     let mut s = rich();