diff --git a/ui-tui/src/components/streamingMarkdown.tsx b/ui-tui/src/components/streamingMarkdown.tsx
index 86dde930e5..1be70b283a 100644
--- a/ui-tui/src/components/streamingMarkdown.tsx
+++ b/ui-tui/src/components/streamingMarkdown.tsx
@@ -42,6 +42,18 @@ import { Md } from './markdown.js'
 // snippets like ` ```\n$$x$$\n``` ` (math example inside a code block)
 // don't double-count. A `$$x$$` line that opens AND closes on its own
 // produces zero net toggles; that's `len >= 4` plus `endsDollar`.
+//
+// NB: this is INTENTIONALLY more conservative than `markdown.tsx`'s
+// parser, which falls back to paragraph rendering when an `$$` opener
+// has no matching closer. The renderer can do that safely because it
+// always sees the full text on every call. The streaming chunker
+// cannot — once a chunk is committed to the monotonic stable prefix it
+// is frozen, so prematurely deciding "this `$$` is just prose" would
+// permanently commit a paragraph rendering that becomes wrong the
+// instant the closer streams in. Treating any unmatched `$$` opener
+// as still-open keeps the boundary parked behind it until the closer
+// arrives (or the stream ends and the non-streaming `<Md>` takes over,
+// at which point the renderer's fallback kicks in correctly).
 const fenceOpenAt = (s: string, end: number) => {
   let codeOpen = false
   let mathOpen = false
diff --git a/ui-tui/src/lib/mathUnicode.ts b/ui-tui/src/lib/mathUnicode.ts
index 7c6f8939ce..17af85ee03 100644
--- a/ui-tui/src/lib/mathUnicode.ts
+++ b/ui-tui/src/lib/mathUnicode.ts
@@ -644,10 +644,13 @@ const replaceFracs = (input: string): string => {
 }
 
 // Wrap multi-token expressions in parens so `\frac{a+b}{c}` becomes
-// `(a+b)/c` rather than `a+b/c`. We only wrap when the expression has
-// loose precedence — additive operators or whitespace that would change
-// meaning under inline `/`. Atomic factors like `n!`, `x^2`, `\sin x`
-// don't need parens; wrapping them just clutters the output.
+// `(a+b)/c` rather than `a+b/c`. We wrap whenever inline `/` would
+// change the meaning — that's any binary operator (`+`, `-`, `*`, `/`)
+// or whitespace separating tokens. `*` and `/` matter because nested
+// fractions and products like `\frac{a*b}{c}` and `\frac{1/x}{y}` would
+// otherwise read as `a*b/c` (right-associative ambiguity) and `1/x/y`.
+// Atomic factors like `n!`, `x^2`, `\sin x` don't trigger any of these
+// and stay un-parenthesised — wrapping them just clutters the output.
 const wrapForFrac = (expr: string) => {
   const trimmed = expr.trim()