Editor: Tab inserts 4 spaces (no TabError) - #13

LiaScript's code editor defaults to tabSize 2 and useSoftTabs false (src/elm/Lia/Markdown/Code/View.elm: Editor.tabSize (int "data-tabsize" 2), Editor.useSoftTabs False). So Tab inserts a real tab character, and in a block indented with 4 spaces Python stops with TabError: inconsistent use of tabs and spaces in indentation.

Change. attach() sets tabSize = 4 and useSoftTabs = true on each lia-editor of the block, through the element's own setters (src/typescript/webcomponents/editor.ts), which pass them on to Ace.

• attach() runs on every DOM change, so when LiaScript recreates the editors (e.g. a slide shown again), the new editors get the setting again. Elm only re-sets these properties when its own value changes, so it doesn't undo them on a re-render.
• A block's own data-tabsize, or a tabSize/useSoftTabs in its data-ace-options (LiaScript puts both on the lia-editor as attributes), still wins.
• An editor that isn't upgraded to LiaScript's element yet is left for the next attach(). Setting the property before the upgrade would hide the setter.
• The README has a short note for course authors.

Test (hosted LiaScript player, this branch's macro vs main's, headless Chrome). In a block indented with 4 spaces: Enter after total = 0, clear the auto-indent, press Tab, type a statement, then ▶ Run.

• A block with <!-- data-tabsize="8" data-ace-options="useSoftTabs=false" --> keeps tab size 8 and hard tabs.
• After going to the next slide and back (the editors are recreated), the first editor again has tab size 4 and soft tabs, both on the element and in Ace's own options.
• node scripts/check-macro.mjs passes.

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