M4.90: Save for Web (Legacy) previews and saves optimised GIF, JPEG, PNG-8 and PNG-24 images, slices and HTML

File > Export > Save for Web (Legacy) (Ctrl/Cmd+Alt+Shift+S) opens a dialog with Original,
Optimized, 2-Up and 4-Up views showing each file's size and download time, and settings for
colour reduction, colours, dither, transparency and matte, interlacing, web snap, lossy GIF,
JPEG quality, the colour table (lock, map to transparent, web shift, sort), image size and
anti-aliasing, Clip to Artboard, sRGB, metadata, slices (all or selected), HTML output and
presets. Preview in Browser opens the HTML page.

Engine: document.exportForWeb, document.exportForWeb.preview (its byte count is the size of
the file Save writes), webExport.settings and webExport.presets.list/save/delete. Saved presets
and the remembered settings are stored in Prefs. Render: quantize_locked, and encode::web for
web snap, colour table edits, lossy GIF and GIF/JPEG comments. PNG files get an sRGB chunk.

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

docs/control-protocol.md

@@ -374,3 +374,12 @@ the save dialog) opens `tiffOptions`, `bmpOptions` or `tgaOptions`: the raster r
 (16, 24, 32). The BMP dialog keeps its choices writable together (OS/2 falls back to 24 bits and turns RLE and flipped
 rows off; RLE turns flipped rows off). `ui.dialog.set` the fields and `ui.dialog.confirm` writes the file(s) with
 `document.export`.
+
+Save for Web: File → Export → Save for Web (Legacy)… (`file.saveForWeb`, Ctrl/Cmd+Alt+Shift+S) opens the `saveForWeb`
+dialog on the remembered settings (`webExport.settings`). Its fields are the `document.exportForWeb` settings
+(`format`, `colors`, `reduction`, `dither`, `quality`, `colorTable`, `width`, `percent`, `output`…; set `preset` to load
+a preset) plus `__view` (`original`, `optimized`, `2up`, `4up`), `__zoom` (`fit` or a percentage), `__kbps` and
+`__color` (the colour table's selected colour). `ui.dialog.confirm` remembers the settings and saves (a save panel for
+the image, or the page with HTML output; the web downloads the files); with `discard: true` it is Done: it remembers
+the settings and closes. `file.saveForWeb` with settings saves without the dialog, and `file.saveForWeb.browser`
+writes the HTML page to a temporary folder and opens it in the default browser (desktop).

docs/mcp.md

@@ -1382,3 +1382,33 @@ on white. TIFF and BMP files open again; `document.formats` lists every option.
 {"name":"run_command","arguments":{"command":"document.export","params":{"format":"bmp","depth":8,"rle":true}}}
 {"name":"export","arguments":{"path":"/tmp/sprite.tga","options":{"depth":32}}}
 ```
+
+## Save for Web
+
+File → Export → Save for Web (Legacy) writes optimised web images: `document.exportForWeb {format: gif|jpg|png8|png24,
+…}` renders the artboard (`clipToArtboard`, the default; `artboard` picks one) or the visible art and the slices, at
+`width`, `height` or `percent`, and encodes it with the format's settings: for GIF and PNG-8 `reduction`, `colors`,
+`dither`, `ditherAmount`, `transparency`, `matte`, `interlaced`, `webSnap`, `lossy` (GIF) and `colorTable {locked,
+transparent, webShift, sort}`; for JPEG `quality`, `progressive`, `optimized`, `embedProfile` and `matte`; for PNG-24
+`transparency`, `matte` and `interlaced`. `metadata` (none, copyright, contact, all) writes File Info as PNG text or a
+GIF/JPEG comment; `convertToSrgb` marks PNGs as sRGB. With slices (`slice.list`) each image slice becomes
+`images/<slice name>.<ext>` (`slices: selected` writes the selected ones, `none` one image); `output: html` adds
+`<stem>.html` placing them, with each slice's URL, target, alt text and status message, and No Image / HTML Text cells.
+Without `path` the files come back as `{name, dataBase64}`.
+
+`document.exportForWeb.preview` returns what Save writes for the same settings without writing it: `bytes` (the exact
+file size), `seconds` to download at `kbps` (default 56.6), the size, and for palette formats the colour table
+(`colors: [{color, source, transparent, locked, webShifted, webSafe}]`). The colour table's lists name colours by
+`source` (the colour the reduction made), so a colour keeps its edits when it is web-shifted or snapped. `slice: n`
+previews one slice; `image: true` adds the file.
+
+Presets: `webExport.presets.list` (built-in ones, then saved ones), `webExport.presets.save {name, newName?, …settings}`,
+`webExport.presets.delete {name}`; any name works as `preset` in the other commands (its settings, then the keys
+given). `webExport.settings {…}` remembers the settings the dialog opens on (`{}` reads them, `reset: true` restores the
+defaults); presets and remembered settings are preferences.
+
+```json
+{"name":"run_command","arguments":{"command":"document.exportForWeb.preview","params":{"format":"gif","colors":32,"dither":"none"}}}
+{"name":"run_command","arguments":{"command":"document.exportForWeb","params":{"path":"/tmp/web/page.html","format":"png8","output":"html"}}}
+{"name":"run_command","arguments":{"command":"webExport.presets.save","params":{"name":"Banner","format":"jpg","quality":70}}}
+```