typst: distinguish function calls from value identifiers; fix math outline

Named value identifiers like 'left', 'center', 'right' were being
highlighted as tok-function (blue) because codeValue used CallExpr
(callSuffix*), which styled any identifier in value position as a
function.  Fix: add FuncExpr { CodeIdent callSuffix+ } (requires at
least one argument list or method suffix) and use it in codeValue
instead of CallExpr.  Plain identifiers in value position now fall
through to CodeIdent → tok-variableName.  CallExpr (callSuffix*) is
kept for codeExprBody and KeywordExpr where zero-suffix idents are
valid.

Tokenizer safety: only acceptToken(CodeIdent) when canShift(CodeIdent)
is true, preventing emission in LALR-merged states where neither
CodeArgKey nor CodeIdent is expected.

Outline: track '$'-parity across lines so that lines inside a display
math block (e.g. '= b+c$') are not incorrectly reported as headings.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

services/web/frontend/js/features/source-editor/languages/typst/document-outline.ts

@@ -23,16 +23,33 @@ const LEVELS: NestingLevel[] = [
 // after it, so this stays clear of code.
 const HEADING_REGEX = /^(=+)[ \t]+(.*\S)[ \t]*$/
 
+// Count unescaped '$' signs on a line to track math-mode parity.
+function countDollars(text: string): number {
+  let count = 0
+  for (let i = 0; i < text.length; i++) {
+    if (text[i] === '\\') { i++; continue }
+    if (text[i] === '$') count++
+  }
+  return count
+}
+
 function computeOutline(
   state: EditorState
 ): ProjectionResult<FlatOutlineItem> {
   const items: FlatOutlineItem[] = []
+  // Track whether we are inside a multi-line display math block.
+  // Each line with an odd number of unescaped '$' toggles the flag.
+  let inMath = false
 
   for (let n = 1; n <= state.doc.lines; n++) {
     const line = state.doc.line(n)
-    const match = HEADING_REGEX.exec(line.text)
-    if (!match) continue
+    const text = line.text
 
+    // Only attempt heading detection when not inside a math block.
+    // (e.g. '= b+c$' on the second line of '$ a \n= b+c$' must be skipped.)
+    if (!inMath) {
+      const match = HEADING_REGEX.exec(text)
+      if (match) {
         const depth = match[1].length
         const level = LEVELS[Math.min(depth, LEVELS.length) - 1]
         // Strip a trailing line comment, then a trailing label.
@@ -50,6 +67,10 @@ function computeOutline(
           level,
         } as FlatOutlineItem)
       }
+    }
+
+    if (countDollars(text) % 2 === 1) inMath = !inMath
+  }
 
   return { items, status: ProjectionStatus.Complete }
 }

services/web/frontend/js/features/source-editor/languages/typst/index.ts

@@ -49,10 +49,12 @@ export const TypstLanguage = LRLanguage.define({
         CodeBool: t.atom,
 
         // Identifiers:
-        //   - direct child of CallExpr → function/method name
-        //   - CodeArgKey (named arg key, emitted by tokenizer before ':') → attributeName
-        //   - everywhere else → plain variable
+        //   CallExpr/CodeIdent  — top-level #func or after keywords (#set text) → function style
+        //   FuncExpr/CodeIdent  — func call inside a value expr (has args/method) → function style
+        //   CodeArgKey          — named arg key (tokenizer pre-disambiguates on ':') → attributeName
+        //   CodeIdent           — plain variable/constant reference (e.g. 'left', 'center') → variable
         'CallExpr/CodeIdent': t.function(t.variableName),
+        'FuncExpr/CodeIdent': t.function(t.variableName),
         CodeArgKey: t.attributeName,
         CodeIdent: t.variableName,
 

services/web/frontend/js/features/source-editor/lezer-typst/tokens.mjs

@@ -370,7 +370,12 @@ export const codeIdentTokenizer = new ExternalTokenizer(
     }
 
     for (let i = 0; i < len; i++) input.advance()
-    input.acceptToken(isArgKey ? CodeArgKey : CodeIdent)
+    if (isArgKey && couldBeKey) {
+      input.acceptToken(CodeArgKey)
+    } else if (couldBeIdent) {
+      input.acceptToken(CodeIdent)
+    }
+    // else: neither token is valid in this state — don't emit
   },
   { contextual: true }
 )

services/web/frontend/js/features/source-editor/lezer-typst/typst.grammar

@@ -74,7 +74,13 @@ codeExprBody {
 KeywordExpr { CodeKeyword CallExpr? }
 AtomExpr    { CodeBool    }
 
+// CallExpr allows zero suffixes — used at top level (#x) and after keywords
+// (#set text(...)) where even a bare identifier is valid as a named reference.
 CallExpr { CodeIdent callSuffix* }
+// FuncExpr requires at least one suffix — used inside codeValue so that
+// 'table(...)' gets tok-function while plain identifiers like 'left'/'center'
+// get tok-variableName instead of being false-positively styled as functions.
+FuncExpr { CodeIdent callSuffix+ }
 callSuffix {
   CodeArgs |
   "." CodeIdent
@@ -91,7 +97,8 @@ codeValue {
   CodeString |
   CodeNumber |
   CodeBool   |
-  CallExpr   |
+  FuncExpr   |
+  CodeIdent  |
   ContentBlock |
   CodeBlock  |
   InlineMath