fix(desktop): artifacts page timestamps render 1970 and local images fail

All three artifact timestamp sources (message.timestamp,
session.last_active, session.started_at) are epoch SECONDS — the
transcript reader and session-date-groups both multiply by 1000 — but
the collector passed them straight to new Date() (ms), so every
artifact rendered as 1970-01-21. Normalize seconds to ms once at
collection; the Date.now() fallback stays ms.

Local file artifacts (e.g. D:\ComfyUI\output\*.png) fell through to
mediaExternalUrl() which yields a file:// URL the renderer cannot
load. Route through the desktop fs bridge whenever it exists —
readDesktopFileDataUrl already dispatches remote REST vs local
Electron internally (#83380).

apps/desktop/src/app/artifacts/artifact-utils.ts

@@ -1,5 +1,4 @@
-import { readDesktopFileDataUrl } from '@/lib/desktop-fs'
-import { filePathFromMediaPath, isRemoteGateway, mediaExternalUrl } from '@/lib/media'
+import { mediaExternalUrl, resolveMediaDisplaySrc } from '@/lib/media'
 import type { SessionInfo, SessionMessage } from '@/types/hermes'
 
 export type ArtifactKind = 'image' | 'file' | 'link'
@@ -185,16 +184,14 @@ function artifactHref(value: string): string {
   return value
 }
 
-export async function artifactImageSrc(value: string, href = artifactHref(value)): Promise<string> {
-  if (/^(?:https?|data):/i.test(value)) {
-    return href
-  }
-
-  if (typeof window !== 'undefined' && window.hermesDesktop && isRemoteGateway()) {
-    return readDesktopFileDataUrl(filePathFromMediaPath(value))
-  }
-
-  return href
+export async function artifactImageSrc(value: string): Promise<string> {
+  // Delegate the whole local/remote ladder to the shared media resolver:
+  // inline (http/data) stays as-is, remote gateway goes through the
+  // authenticated fs bridge, local desktop through the Electron
+  // readFileDataUrl, and bare non-path link values fall through untouched.
+  // Reimplementing that ladder here would drift from resolveMediaDisplaySrc
+  // and regress one of its legs (#83380).
+  return resolveMediaDisplaySrc(value)
 }
 
 function artifactLabel(value: string): string {

apps/desktop/src/app/artifacts/index.test.ts

@@ -309,6 +309,19 @@ ${payload}
     expect(fromNow[0]?.timestamp).toBe(now)
   })
 
+  it('resolves local file image artifacts through the desktop fs bridge', async () => {
+    const readFileDataUrl = vi.fn(async () => 'data:image/png;base64,TE9DQUw=')
+    vi.stubGlobal('window', { hermesDesktop: { readFileDataUrl } })
+
+    // Local desktop (connection mode != 'remote'): a local image_generate
+    // output path must be read through the Electron bridge, not left as a
+    // file:// URL the renderer cannot load (#83380).
+    const path = '/home/me/.hermes/cache/image_generate/out.png'
+
+    await expect(artifactImageSrc(path)).resolves.toBe('data:image/png;base64,TE9DQUw=')
+    expect(readFileDataUrl).toHaveBeenCalledWith(path)
+  })
+
   it('resolves remote image artifact thumbnails through the desktop fs bridge', async () => {
     const api = vi.fn(async ({ path }: { path: string }) => {
       if (path.startsWith('/api/fs/read-data-url?')) {
@@ -322,9 +335,8 @@ ${payload}
     $connection.set({ baseUrl: 'https://gw', mode: 'remote', token: 'secret' } as never)
 
     const path = '/Users/me/.hermes/skills/work-esab/references/images/manual-step03.jpeg'
-    const downloadHref = `https://gw/api/files/download?path=${encodeURIComponent(path)}&token=secret`
 
-    await expect(artifactImageSrc(path, downloadHref)).resolves.toBe('data:image/jpeg;base64,cmVtb3Rl')
+    await expect(artifactImageSrc(path)).resolves.toBe('data:image/jpeg;base64,cmVtb3Rl')
 
     expect(api).toHaveBeenCalledWith({
       path: '/api/fs/read-data-url?path=%2FUsers%2Fme%2F.hermes%2Fskills%2Fwork-esab%2Freferences%2Fimages%2Fmanual-step03.jpeg'

apps/desktop/src/app/artifacts/index.tsx

@@ -474,7 +474,7 @@ function ArtifactImageCard({ artifact, failedImage, onImageError, onOpenChat }:
     let active = true
 
     setSrc('')
-    void artifactImageSrc(artifact.value, artifact.href)
+    void artifactImageSrc(artifact.value)
       .then(nextSrc => {
         if (active) {
           setSrc(nextSrc)