fix(desktop): keep authored link labels and identifier casing

MarkdownLink dropped formatted link labels: childrenToText only handled
plain strings, so an inline-code label ([`v1.0.1`](url)) fell through to a
title fetch or a URL-slug fallback that title-cased the identifier.
Flatten element children so the authored label wins with exact casing,
and keep the casing of separator-less slug tokens that look like
identifiers (digits, dots, mixed case) instead of title-casing them.

Fixes https://github.com/NousResearch/hermes-agent/issues/121321

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

@@ -0,0 +1,66 @@
+import { cleanup, render, screen } from '@testing-library/react'
+import { afterEach, describe, expect, it, vi } from 'vitest'
+
+import { MarkdownTextContent } from './markdown-text'
+
+// Regression for #121321: authored markdown link labels are the text the
+// model wrote, and formatted labels count. An inline-code label
+// ([`v1.0.1`](url)) used to be dropped by childrenToText (it only handled
+// plain strings), so the link fell through to a title fetch or a URL-slug
+// fallback label that title-cased the identifier (`V1.0.1`). The authored
+// label must win, with its exact casing preserved. Bare URLs keep their
+// identifier casing too when no title is fetched (`README.md`, not
+// `README.Md`).
+describe('MarkdownLink authored labels', () => {
+  afterEach(cleanup)
+
+  it('preserves an inline-code link label with its exact casing', async () => {
+    render(
+      <MarkdownTextContent isRunning={false} text="Tagged [`v1.0.1`](https://example.com/releases/tag/v1.0.1)." />
+    )
+
+    await screen.findByText('v1.0.1')
+    const anchor = screen.getByRole('link') as HTMLAnchorElement
+
+    expect(anchor.getAttribute('href')).toBe('https://example.com/releases/tag/v1.0.1')
+    expect(anchor.textContent).toContain('v1.0.1')
+  })
+
+  it('prefers the authored inline-code label over a fetched page title', async () => {
+    const fetchLinkTitle = vi.fn().mockResolvedValue('Releases · example')
+
+    ;(window as unknown as { hermesDesktop: object }).hermesDesktop = {
+      fetchLinkTitle,
+      openExternal: vi.fn().mockResolvedValue(undefined)
+    }
+
+    try {
+      render(
+        <MarkdownTextContent isRunning={false} text="Tagged [`v1.0.1`](https://example.com/releases/tag/v1.0.1)." />
+      )
+
+      await screen.findByText('v1.0.1')
+      expect(fetchLinkTitle).not.toHaveBeenCalled()
+    } finally {
+      delete (window as unknown as { hermesDesktop?: object }).hermesDesktop
+    }
+  })
+
+  it('keeps a bare URL fully visible with its exact casing', async () => {
+    render(<MarkdownTextContent isRunning={false} text="See https://example.com/repository/blob/main/README.md" />)
+
+    const anchor = (await screen.findByRole('link')) as HTMLAnchorElement
+
+    expect(anchor.getAttribute('href')).toBe('https://example.com/repository/blob/main/README.md')
+    // The full URL is the label (#121007), so its identifier casing is
+    // exactly what the sender wrote — never a title-cased `README.Md`.
+    expect(anchor.textContent).toContain('README.md')
+    expect(anchor.textContent).not.toContain('README.Md')
+  })
+
+  it('keeps a plain authored label untouched', () => {
+    render(<MarkdownTextContent isRunning={false} text="[v1.0.1](https://example.com/releases/tag/v1.0.1)" />)
+
+    expect(screen.getByRole('link').textContent).toContain('v1.0.1')
+  })
+})

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

@@ -8,7 +8,7 @@ import {
   tailBoundedRemend
 } from '@assistant-ui/react-streamdown'
 import type { code as streamdownCode } from '@streamdown/code'
-import { type ComponentProps, memo, type ReactNode, useEffect, useMemo, useState } from 'react'
+import { type ComponentProps, isValidElement, memo, type ReactNode, useEffect, useMemo, useState } from 'react'
 
 import { ExpandableBlock } from '@/components/chat/expandable-block'
 import { PreviewAttachment } from '@/components/chat/preview-attachment'
@@ -249,13 +249,29 @@ function MediaPlaybackAttachment({ path }: { path: string }) {
   )
 }
 
+// Authored labels can be formatted markdown — an inline-code label like
+// [`v1.0.1`](url) arrives as a <code> element, not a plain string. Extract
+// the text so MarkdownLink can pass it as `fallbackLabel`; dropping it sent
+// the link down the title-fetch / URL-slug fallback path instead (#121321).
 function childrenToText(children: unknown): string {
-  if (typeof children === 'string' || typeof children === 'number') {
-    return String(children).trim()
+  return flattenChildrenToText(children).trim()
+}
+
+function flattenChildrenToText(node: unknown): string {
+  if (node === null || node === undefined || typeof node === 'boolean') {
+    return ''
   }
 
-  if (Array.isArray(children) && children.every(c => typeof c === 'string' || typeof c === 'number')) {
-    return children.join('').trim()
+  if (typeof node === 'string' || typeof node === 'number') {
+    return String(node)
+  }
+
+  if (Array.isArray(node)) {
+    return node.map(flattenChildrenToText).join('')
+  }
+
+  if (isValidElement<{ children?: unknown }>(node)) {
+    return flattenChildrenToText(node.props.children)
   }
 
   return ''

apps/desktop/src/lib/external-link.test.tsx

@@ -70,6 +70,17 @@ describe('external link helpers', () => {
     ).toBe('From Fajardo Icacos Island Full Day Catamaran Trip')
   })
 
+  // Regression for #121321: a separator-less slug token that looks like a
+  // case-sensitive identifier (a digit, a dot, or mixed case — release
+  // tags, filenames) must keep its exact casing; title-casing it invented a
+  // different identifier (`V1.0.1`, `README.Md`) than the one authored. A
+  // plain lowercase word token is not an identifier and still title-cases.
+  it('keeps identifier casing in separator-less slug tokens but still title-cases words', () => {
+    expect(urlSlugTitleLabel('https://example.com/releases/tag/v1.0.1')).toBe('v1.0.1')
+    expect(urlSlugTitleLabel('https://example.com/repository/blob/main/README.md')).toBe('README.md')
+    expect(urlSlugTitleLabel('https://example.com/p/quantumcomputing')).toBe('Quantumcomputing')
+  })
+
   it('filters out local/non-http targets for title fetches', () => {
     expect(isTitleFetchable('https://www.expedia.com/things-to-do/foo')).toBe(true)
     expect(isTitleFetchable('http://localhost:5174')).toBe(false)

apps/desktop/src/lib/external-link.tsx

@@ -104,10 +104,21 @@ export function urlSlugTitleLabel(value: string): string {
       continue
     }
 
-    const titled = cleaned.replace(/\b[a-z]/g, c => c.toUpperCase())
+    // Title-case word slugs (`some-guide` → `Some Guide`), but keep the
+    // exact casing of a separator-less token that looks like a
+    // case-sensitive identifier — it carries a digit, a dot, or mixed case,
+    // as in a release tag (`v1.0.1`) or a filename (`README.md`) — so the
+    // link never invents a different identifier. A plain lowercase word
+    // (`quantumcomputing` → `Quantumcomputing`) still title-cases. (#121321)
+    const looksLikeIdentifier = /\d/.test(cleaned) || /[A-Z]/.test(cleaned) || cleaned.includes('.')
 
-    if (titled.length >= 4) {
-      return titled
+    const label =
+      looksLikeIdentifier && !cleaned.includes(' ')
+        ? cleaned
+        : cleaned.replace(/\b[a-z]/g, c => c.toUpperCase())
+
+    if (label.length >= 4) {
+      return label
     }
   }