Answer stability round 1: the escape flags flow through return values, and V8's failed typed-array allocation is refused as its memory running short

README.md

@@ -410,9 +410,9 @@ typed on `ConvertError` takes both.
 
 A call reports the first refusal in document order and stops, so a document with several surfaces
 them one per call. Every refusal is deterministic — there is no I/O anywhere — so a retry returns
-the identical error: fix the input, or set the document aside. On JavaScriptCore (Bun, Safari),
-retry once any call that returns `unsupported-node-shape` at the empty path: that engine reports a
-heap running short the same way as a string too long to build.
+the identical error: fix the input, or set the document aside. The exception is memory running
+short, which an engine may report as `unsupported-node-shape` at the empty path, and JavaScriptCore
+(Bun, Safari) reports the same way as a string too long to build: retry such a call once.
 
 ### Parsing
 

src/markdown/emit/line-escaping.ts

@@ -95,8 +95,7 @@ function escape(segments: readonly InlineSegment[], container: LineContainer, cl
     const code = codes[index]
     return code === undefined ? undefined : escapingCodes[code]
   }
-  const escaped = escapeClaims(scan, escapings, container, claims)
-  escapeClosedRuns(scan, escapings, escaped)
+  const escaped = escapeClosedRuns(scan, escapings, escapeClaims(scan, escapings, container, claims))
   const { output, placements } = backslashed(segments, scan, escaped)
   if (container === 'paragraph' && opensLinkDefinition(output)) {
     if (segments[0]?.nodes !== undefined) return { line: output, openingLinkAsDirective: true, unspellableRuns: [] }
@@ -227,7 +226,7 @@ function claimsCharacter({ container, escapings, headingCloser, linkClose, scan
 
 // CommonMark reads no escape inside a code span, so a backtick string left beside an escape still closes a span that an earlier bare run of its length opens.
 // The walk runs backwards and escapes only the run it just read, so every index it reads still holds the claims alone.
-function escapeClosedRuns(scan: string, escapings: Escapings, escaped: Uint8Array): void {
+function escapeClosedRuns(scan: string, escapings: Escapings, escaped: Uint8Array): Uint8Array {
   // The lengths of the backtick strings escapes leave: a bare run of one of these lengths would open a span one of them closes, so it is escaped too.
   const formed = new Set<number>()
   let end = scan.length - 1
@@ -252,6 +251,7 @@ function escapeClosedRuns(scan: string, escapings: Escapings, escaped: Uint8Arra
     }
     end = start - 1
   }
+  return escaped
 }
 
 // One emphasis run, the innermost, or every highlight run the line cannot spell.

src/markdown/length-bound.test.ts

@@ -31,6 +31,7 @@ test('refuses a string past the bound as too long on every engine, and names any
     ok: false,
   })
   assert.equal(withinEngineLimits(thrown('RangeError', 'Invalid array length')).ok, false)
+  assert.equal(withinEngineLimits(thrown('RangeError', 'Array buffer allocation failed')).ok, false)
   assert.deepEqual(
     withinEngineLimits(() => success('x')),
     { ok: true, value: 'x' },

src/markdown/length-bound.ts

@@ -3,9 +3,9 @@ import { failure, success, type Result } from '../result.ts'
 // V8's longest string (docs/decisions.md §Markdown past V8's longest string is refused on every engine).
 export const longestMarkdown = 2 ** 29 - 24
 
-// Measured on Firefox 155, Node 24 and Bun 1.4. SpiderMonkey's overflow and V8's string overflow both mean a string past longestMarkdown; the other two name an engine's own limit, and JavaScriptCore's also a heap running short.
+// Measured on Firefox 155, Node 24 and Bun 1.4. SpiderMonkey's overflow and V8's string overflow both mean a string past longestMarkdown; the others name an engine's own limit or its memory running short.
 const pastLongestString = ['InternalError: allocation size overflow', 'RangeError: Invalid string length']
-const pastEngineLimit = ['RangeError: Invalid array length', 'RangeError: Out of memory']
+const pastEngineLimit = ['RangeError: Array buffer allocation failed', 'RangeError: Invalid array length', 'RangeError: Out of memory']
 
 export function tooLong<T>(): Result<T> {
   return failure('unsupported-node-shape', `the markdown for this document, or for a directive's plain CommonMark, would be longer than ${longestMarkdown} characters, the longest this library writes`, [])