docs(desktop): correct streaming-repair comments after the defer/smooth swap

the parseIncompleteMarkdown comment implied the reveal frontier is repaired; repair runs on the full accumulated text, so reword it to say that. drop the now-dead "multiple surfaces render the same content" clause from the block-cache comment (the smooth and defer wrappers that caused it were removed), and trim the math-preprocess comment to the load-bearing prose-only constraint.

apps/desktop/src/components/assistant-ui/markdown-text.tsx

@@ -62,8 +62,7 @@ function preprocessWithTailRepair(text: string): string {
 // Memoized block splitter. Streamdown calls `parseMarkdownIntoBlocks` (a full
 // `marked` lex of the entire message, ~1.6ms per 28KB) inside a useMemo keyed
 // on the text — but the same text is re-lexed every time a message REMOUNTS
-// (virtualizer scroll, session switch) and whenever multiple surfaces render
-// the same content (remount, session switch). A small module-level
+// (virtualizer scroll, session switch). A small module-level
 // LRU keyed by the exact source string removes all of those repeat parses
 // with zero correctness risk (same input → same output). Streaming tail
 // growth misses the cache by design (every flush is a new string) — that
@@ -523,10 +522,11 @@ function MarkdownTextSurface({ containerClassName, containerProps, defer, smooth
       defer={defer}
       lineNumbers={false}
       mode="streaming"
-      // The built-in tail-bounded remend is disabled when a custom
-      // parseMarkdownIntoBlocksFn is supplied, so repair runs in
-      // preprocessWithTailRepair instead. parseIncompleteMarkdown stays
-      // false to avoid a second full-text remend pass.
+      // Incomplete-markdown repair runs in preprocessWithTailRepair on the
+      // full accumulated text; the built-in tail-bounded remend is disabled
+      // because a custom parseMarkdownIntoBlocksFn is supplied, and
+      // parseIncompleteMarkdown stays false to avoid a second full-text
+      // remend pass.
       parseIncompleteMarkdown={false}
       parseMarkdownIntoBlocksFn={parseMarkdownIntoBlocksCached}
       plugins={plugins}

apps/desktop/src/lib/markdown-preprocess.ts

@@ -344,10 +344,8 @@ export function preprocessMarkdown(text: string): string {
       const leading = part.match(/^\s*/)?.[0] ?? ''
       const trailing = part.match(/\s*$/)?.[0] ?? ''
 
-      // normalizeMathDelimiters rewrites LaTeX bracket delimiters and
-      // custom math tags to dollar form. escapeCurrencyDollars escapes
-      // `$<digit>` so currency isn't eaten as math. Both run only on
-      // prose segments so code blocks stay untouched.
+      // Run only on prose segments so `$5` literals and `\(` inside code
+      // blocks stay intact.
       const transformed = normalizeVisibleProse(
         stripPreviewTargets(normalizeMathDelimiters(escapeCurrencyDollars(part)))
       )