diff --git a/src/components/Collapsible/index.tsx b/src/components/Collapsible/index.tsx
index 263c6e53..60d0455a 100644
--- a/src/components/Collapsible/index.tsx
+++ b/src/components/Collapsible/index.tsx
@@ -58,10 +58,13 @@ export default function Collapsible({
     >
       {children}
       {shouldCollapse && !expanded && (
-        <div className="absolute bottom-0 h-40 w-full bg-gradient-to-b from-transparent to-background/90 flex items-end justify-center pb-4">
-          <div className="bg-background rounded-md">
+        <div
+          className="pointer-events-none absolute bottom-0 z-20 flex h-40 w-full items-end justify-center bg-gradient-to-b from-transparent to-background/90 pb-4"
+          data-collapsible-show-more
+        >
+          <div className="pointer-events-auto rounded-md">
             <Button
-              className="bg-foreground hover:bg-foreground/80"
+              className="bg-foreground text-background hover:bg-foreground/90 hover:text-background"
               onClick={(e) => {
                 e.stopPropagation()
                 setExpanded(!expanded)
diff --git a/src/components/Image/index.tsx b/src/components/Image/index.tsx
index ec980f16..1dc3f88d 100644
--- a/src/components/Image/index.tsx
+++ b/src/components/Image/index.tsx
@@ -2,6 +2,7 @@ import { Skeleton } from '@/components/ui/skeleton'
 import { cn } from '@/lib/utils'
 import { isRenderableMediaUrl, isSafeMediaUrl } from '@/lib/url'
 import { TImetaInfo } from '@/types'
+import { blurHashPlaceholderForMediaUrl } from '@/lib/media-placeholder-blurhash'
 import { decode } from 'blurhash'
 import { ImageOff } from 'lucide-react'
 import { CSSProperties, HTMLAttributes, useEffect, useMemo, useRef, useState } from 'react'
@@ -80,6 +81,15 @@ export default function Image({
   const badSrc = !imageUrl?.trim() || !isRenderableMediaUrl(imageUrl.trim())
   const showErrorState = hasError || badSrc
 
+  /** NIP-94 blurhash when present; otherwise a stable URL-derived placeholder (many events omit blurhash). */
+  const effectiveBlurHash = useMemo(() => {
+    const fromTag = blurHash?.trim()
+    if (fromTag) return fromTag
+    const u = url?.trim()
+    if (!u) return undefined
+    return blurHashPlaceholderForMediaUrl(u)
+  }, [blurHash, url])
+
   const clearLoadWatch = () => {
     if (loadWatchRef.current != null) {
       clearTimeout(loadWatchRef.current)
@@ -163,13 +173,15 @@ export default function Image({
       {...props}
     >
       {displaySkeleton && !showErrorState && (
-        <span className="absolute inset-0 z-10 block rounded-lg bg-muted/30">
-          {blurHash ? (
+        <span className="absolute inset-0 z-10 block rounded-lg bg-muted/40">
+          {effectiveBlurHash ? (
             <BlurHashCanvas
-              blurHash={blurHash}
+              blurHash={effectiveBlurHash}
               className={cn(
                 'absolute inset-0 transition-opacity duration-500 rounded-lg',
-                !revealed ? 'opacity-100' : 'opacity-0'
+                // Keep placeholder visible while the full image is still loading (auto-load),
+                // otherwise both blur and <img> are opacity-0 and only a faint bg shows (looks like a white box).
+                !revealed || isLoading ? 'opacity-100' : 'opacity-0'
               )}
             />
           ) : !revealed && !isLoading ? (
@@ -271,12 +283,22 @@ function BlurHashCanvas({ blurHash, className = '' }: { blurHash: string; classN
 
   if (!blurHash) return null
 
+  // Failed decode or unsupported hash: empty <canvas> often paints as solid white — use muted fill instead.
+  if (!pixels) {
+    return (
+      <span
+        className={cn('block h-full w-full rounded-lg bg-muted object-cover', className)}
+        aria-hidden
+      />
+    )
+  }
+
   return (
     <canvas
       ref={canvasRef}
       width={blurHashWidth}
       height={blurHashHeight}
-      className={cn('w-full h-full object-cover rounded-lg', className)}
+      className={cn('h-full w-full object-cover rounded-lg', className)}
       style={{
         imageRendering: 'auto',
         filter: 'blur(0.5px)'
diff --git a/src/components/MediaPlayer/index.tsx b/src/components/MediaPlayer/index.tsx
index 04186ca9..9cfc02a6 100644
--- a/src/components/MediaPlayer/index.tsx
+++ b/src/components/MediaPlayer/index.tsx
@@ -1,5 +1,6 @@
+import { isImage } from '@/lib/url'
 import { useContentPolicy } from '@/providers/ContentPolicyProvider'
-import { useEffect, useState } from 'react'
+import { useEffect, useMemo, useState } from 'react'
 import AudioPlayer from '../AudioPlayer'
 import VideoPlayer from '../VideoPlayer'
 import ExternalLink from '../ExternalLink'
@@ -23,6 +24,14 @@ export default function MediaPlayer({
   const [display, setDisplay] = useState(autoLoadMedia)
   const [mediaType, setMediaType] = useState<'video' | 'audio' | null>(null)
 
+  // imeta `thumb` / `image` are sometimes the same .mp4 as `url` — <img> cannot use that, and it
+  // would hide the blurhash placeholder in LazyMediaTapPlaceholder.
+  const imagePoster = useMemo(() => {
+    const p = poster?.trim()
+    if (!p) return undefined
+    return isImage(p) ? p : undefined
+  }, [poster])
+
   useEffect(() => {
     if (autoLoadMedia) {
       setDisplay(true)
@@ -78,7 +87,7 @@ export default function MediaPlayer({
     return (
       <LazyMediaTapPlaceholder
         src={src}
-        posterUrl={poster}
+        posterUrl={imagePoster}
         blurHash={blurHash}
         onActivate={() => setDisplay(true)}
         className={className}
@@ -91,7 +100,7 @@ export default function MediaPlayer({
   }
 
   if (mediaType === 'video') {
-    return <VideoPlayer src={src} className={className} poster={poster} />
+    return <VideoPlayer src={src} className={className} poster={imagePoster} />
   }
 
   return <AudioPlayer src={src} className={className} />
diff --git a/src/components/Note/MarkdownArticle/MarkdownArticle.tsx b/src/components/Note/MarkdownArticle/MarkdownArticle.tsx
index 14253d13..1f3e8ddc 100644
--- a/src/components/Note/MarkdownArticle/MarkdownArticle.tsx
+++ b/src/components/Note/MarkdownArticle/MarkdownArticle.tsx
@@ -4836,7 +4836,8 @@ export default function MarkdownArticle({
       if (info.m?.startsWith('video/') || isVideo(info.url)) {
         const cleaned = cleanUrl(info.url)
         const posterUrl = info.image || info.thumb
-        if (cleaned && posterUrl) {
+        // thumb is often wrongly set to the same video URL; only real image URLs work as <img poster>.
+        if (cleaned && posterUrl && isImage(posterUrl)) {
           map.set(cleaned, posterUrl)
         }
       }
diff --git a/src/components/UserAvatar/index.tsx b/src/components/UserAvatar/index.tsx
index ad3be03c..ac46f301 100644
--- a/src/components/UserAvatar/index.tsx
+++ b/src/components/UserAvatar/index.tsx
@@ -28,12 +28,25 @@ const loadedAvatarUrls = new Set<string>()
  * Non-blocking HEAD request to get Content-Length for a URL.
  * Result is cached permanently in memory. Resolves null on CORS failure or missing header.
  */
+const AVATAR_HEAD_TIMEOUT_MS = 3000
+
 async function fetchUrlSizeBytes(url: string): Promise<number | null> {
   if (urlSizeCache.has(url)) return urlSizeCache.get(url)!
   try {
-    const res = await fetch(url, { method: 'HEAD' })
+    const ctrl = new AbortController()
+    const timer = window.setTimeout(() => ctrl.abort(), AVATAR_HEAD_TIMEOUT_MS)
+    const res = await fetch(url, { method: 'HEAD', signal: ctrl.signal })
+    clearTimeout(timer)
+    if (!res.ok) {
+      urlSizeCache.set(url, null)
+      return null
+    }
     const cl = res.headers.get('content-length')
     const size = cl ? parseInt(cl, 10) : null
+    if (size != null && !Number.isFinite(size)) {
+      urlSizeCache.set(url, null)
+      return null
+    }
     urlSizeCache.set(url, size)
     return size
   } catch {
@@ -59,8 +72,7 @@ function useDeferRemoteProfileAvatar(
     if (!a || !isHttpOrHttpsUrl(a)) return ''
     // Video files don't have a /thumb/ route — serve them as-is.
     if (isVideo(a)) return a
-    // Always use the nostr.build thumbnail route for profile pictures — it's
-    // typically < 50 KB regardless of the original file size.
+    // i.nostr.build serves /thumb/… for images (cdn.nostr.build does not).
     return toNostrBuildThumbUrl(a)
   }, [profileAvatar])
 
diff --git a/src/lib/nostr-build.test.ts b/src/lib/nostr-build.test.ts
new file mode 100644
index 00000000..12901eb2
--- /dev/null
+++ b/src/lib/nostr-build.test.ts
@@ -0,0 +1,24 @@
+import { describe, expect, it } from 'vitest'
+import { canUseNostrBuildThumb, toNostrBuildThumbUrl } from './nostr-build'
+
+describe('nostr-build thumb URLs', () => {
+  it('allows /thumb/ rewrite only for i.nostr.build images', () => {
+    expect(canUseNostrBuildThumb('https://i.nostr.build/foo.webp')).toBe(true)
+    expect(toNostrBuildThumbUrl('https://i.nostr.build/foo.webp')).toBe(
+      'https://i.nostr.build/thumb/foo.webp'
+    )
+  })
+
+  it('does not rewrite cdn.nostr.build (no /thumb/ service)', () => {
+    expect(canUseNostrBuildThumb('https://cdn.nostr.build/i/abc123.webp')).toBe(false)
+    expect(toNostrBuildThumbUrl('https://cdn.nostr.build/i/abc123.webp')).toBe(
+      'https://cdn.nostr.build/i/abc123.webp'
+    )
+  })
+
+  it('does not rewrite video URLs on i.nostr.build', () => {
+    const u = 'https://i.nostr.build/bar.webm'
+    expect(canUseNostrBuildThumb(u)).toBe(false)
+    expect(toNostrBuildThumbUrl(u)).toBe(u)
+  })
+})
diff --git a/src/lib/nostr-build.ts b/src/lib/nostr-build.ts
index e1edb782..cd97eaf7 100644
--- a/src/lib/nostr-build.ts
+++ b/src/lib/nostr-build.ts
@@ -1,14 +1,16 @@
 /**
- * Utilities for nostr.build CDN URLs.
+ * Utilities for nostr.build media URLs.
  *
- * nostr.build generates a lightweight thumbnail at /thumb/<filename> for every
- * uploaded image. Thumbnails are typically < 50 KB regardless of the original
- * file size — a huge bandwidth win for profile pictures and feed previews.
- * Note: the /thumb/ route only works for image files — never apply it to video URLs.
+ * Thumbnails at `/thumb/<path>` are served on **i.nostr.build** only. Other hosts
+ * (e.g. **cdn.nostr.build**) do not provide that route — never rewrite those URLs.
+ *
+ * The /thumb/ route is for **images** only — never apply it to video URLs.
  */
 
 import { isVideo } from './url'
 
+const I_NOSTR_BUILD = 'i.nostr.build'
+
 /** Returns true when a URL is hosted on any nostr.build domain. */
 export function isNostrBuildUrl(url: string): boolean {
   const u = (url ?? '').trim()
@@ -20,15 +22,17 @@ export function isNostrBuildUrl(url: string): boolean {
   }
 }
 
-/** Returns true when the URL is on nostr.build but does NOT yet use the /thumb/ path, and is not a video file. */
+/**
+ * True when we may rewrite `url` to i.nostr.build’s `/thumb/…` variant.
+ * Only **i.nostr.build** serves generated thumbs; cdn.nostr.build does not.
+ */
 export function canUseNostrBuildThumb(url: string): boolean {
   const u = (url ?? '').trim()
   if (!u) return false
-  // /thumb/ is image-only on nostr.build — never apply it to video files
   if (isVideo(u)) return false
   try {
     const parsed = new URL(u)
-    if (!parsed.hostname.endsWith('nostr.build')) return false
+    if (parsed.hostname !== I_NOSTR_BUILD) return false
     const p = parsed.pathname
     return p !== '/thumb' && !p.startsWith('/thumb/')
   } catch {
@@ -37,9 +41,8 @@ export function canUseNostrBuildThumb(url: string): boolean {
 }
 
 /**
- * Returns the nostr.build thumbnail URL for `url`, inserting `/thumb` before the
- * filename path segment. Returns the original URL unchanged if it is not on
- * nostr.build, already uses /thumb/, or cannot be parsed.
+ * Returns the i.nostr.build thumbnail URL for `url` (insert `/thumb` before the path).
+ * Returns `url` unchanged if not on i.nostr.build, already under /thumb/, or invalid.
  */
 export function toNostrBuildThumbUrl(url: string): string {
   const u = (url ?? '').trim()
diff --git a/src/lib/tag.ts b/src/lib/tag.ts
index 19f959c8..3a6791d3 100644
--- a/src/lib/tag.ts
+++ b/src/lib/tag.ts
@@ -19,6 +19,27 @@ export function tagNameEquals(tagName: string) {
 
 const NOTE_HEX_ID_RE = /^[0-9a-f]{64}$/i
 
+/**
+ * Some clients publish non-NIP-94 `m` values, e.g. `gif(694866 bytes)`.
+ * Map common image tokens to a proper MIME type for routing and media extraction.
+ */
+function normalizeImetaMimeField(raw: string): string {
+  const s = raw.trim()
+  if (/^(image|video|audio)\//i.test(s)) return s
+  const m = s.match(/^(gif|jpe?g|png|webp|avif|heic|svg)\b/i)
+  if (m) {
+    const k = m[1].toLowerCase()
+    if (k === 'jpeg' || k === 'jpg') return 'image/jpeg'
+    if (k === 'svg') return 'image/svg+xml'
+    if (k === 'gif') return 'image/gif'
+    if (k === 'png') return 'image/png'
+    if (k === 'webp') return 'image/webp'
+    if (k === 'avif') return 'image/avif'
+    if (k === 'heic') return 'image/heic'
+  }
+  return s
+}
+
 /** First hex event id on an `e` / `E` tag (reactions, reposts, replies). */
 export function getFirstHexEventIdFromETags(tags: string[][]): string | undefined {
   for (const t of tags) {
@@ -160,7 +181,7 @@ export function getImetaInfoFromImetaTag(tag: string[], pubkey?: string): TImeta
   }
   
   if (mimeType) {
-    imeta.m = mimeType
+    imeta.m = normalizeImetaMimeField(mimeType)
   }
   
   // Parse alt text
diff --git a/src/lib/upload-nip94-imeta.ts b/src/lib/upload-nip94-imeta.ts
index 8928be62..7b9b8234 100644
--- a/src/lib/upload-nip94-imeta.ts
+++ b/src/lib/upload-nip94-imeta.ts
@@ -84,6 +84,119 @@ function videoDimensionsFromFile(file: File): Promise<{ width: number; height: n
   })
 }
 
+/** Frame grab + blurhash for one video file (used for NIP-94 before/after main upload). */
+export type VideoNip94PreviewResult = {
+  blurhash: string | null
+  posterJpeg: File | null
+  width: number
+  height: number
+}
+
+const VIDEO_PREVIEW_LOAD_MS = 18_000
+const VIDEO_PREVIEW_SEEK_MS = 12_000
+
+/**
+ * Decode one frame from a local video file: JPEG poster (for separate upload) + blurhash + dimensions.
+ * Never throws; returns null fields on failure (unsupported codec, timeout, etc.).
+ */
+export async function extractVideoNip94Preview(file: File): Promise<VideoNip94PreviewResult | null> {
+  if (!file.type.startsWith('video/')) return null
+
+  const objectUrl = URL.createObjectURL(file)
+  const video = document.createElement('video')
+  video.muted = true
+  video.playsInline = true
+  video.preload = 'auto'
+
+  const cleanup = () => {
+    try {
+      URL.revokeObjectURL(objectUrl)
+    } catch {
+      /* ignore */
+    }
+    video.removeAttribute('src')
+    video.load()
+  }
+
+  try {
+    await new Promise<void>((resolve, reject) => {
+      const timer = window.setTimeout(() => reject(new Error('load timeout')), VIDEO_PREVIEW_LOAD_MS)
+      const done = (err?: Error) => {
+        clearTimeout(timer)
+        if (err) reject(err)
+        else resolve()
+      }
+      video.onloadeddata = () => done()
+      video.onerror = () => done(new Error('video load error'))
+      video.src = objectUrl
+    })
+
+    const w = video.videoWidth
+    const h = video.videoHeight
+    if (!w || !h) return null
+
+    const dur = Number.isFinite(video.duration) && video.duration > 0 ? video.duration : 0
+    const tseek = dur > 0 ? Math.min(Math.max(0.05, dur * 0.1), dur - 0.05) : 0.1
+    video.currentTime = tseek
+
+    await new Promise<void>((resolve, reject) => {
+      const timer = window.setTimeout(() => reject(new Error('seek timeout')), VIDEO_PREVIEW_SEEK_MS)
+      video.onseeked = () => {
+        clearTimeout(timer)
+        resolve()
+      }
+      video.onerror = () => {
+        clearTimeout(timer)
+        reject(new Error('seek error'))
+      }
+    })
+
+    const maxPosterSide = 1280
+    const ps = Math.min(1, maxPosterSide / Math.max(w, h))
+    const pw = Math.max(1, Math.round(w * ps))
+    const ph = Math.max(1, Math.round(h * ps))
+    const canvas = document.createElement('canvas')
+    canvas.width = pw
+    canvas.height = ph
+    const ctx = canvas.getContext('2d')
+    if (!ctx) return { blurhash: null, posterJpeg: null, width: w, height: h }
+    ctx.drawImage(video, 0, 0, pw, ph)
+
+    const maxBh = 64
+    const bs = Math.min(1, maxBh / Math.max(pw, ph))
+    const bw = Math.max(1, Math.round(pw * bs))
+    const bhH = Math.max(1, Math.round(ph * bs))
+    const bhCanvas = document.createElement('canvas')
+    bhCanvas.width = bw
+    bhCanvas.height = bhH
+    const bhCtx = bhCanvas.getContext('2d')
+    let blurhash: string | null = null
+    if (bhCtx) {
+      bhCtx.drawImage(canvas, 0, 0, bw, bhH)
+      try {
+        const { data } = bhCtx.getImageData(0, 0, bw, bhH)
+        blurhash = encodeBlurhash(data, bw, bhH, 4, 3)
+      } catch {
+        blurhash = null
+      }
+    }
+
+    const jpegBlob: Blob | null = await new Promise((res) =>
+      canvas.toBlob((b) => res(b), 'image/jpeg', 0.82)
+    )
+    const base = file.name.replace(/\.[^.]+$/, '') || 'video'
+    const posterJpeg = jpegBlob
+      ? new File([jpegBlob], `${base}-poster.jpg`, { type: 'image/jpeg' })
+      : null
+
+    return { blurhash, posterJpeg, width: w, height: h }
+  } catch {
+    return null
+  } finally {
+    cleanup()
+  }
+}
+
 function shouldTryBlurhash(mime: string | undefined): boolean {
   if (!mime || !mime.startsWith('image/')) return false
   if (mime === 'image/svg+xml') return false
@@ -194,7 +307,11 @@ export function nip94PairsToImetaTag(pairs: string[][]): string[] {
 /**
  * Client-side NIP-94 fields for the uploaded bytes (post-compression) and final URL.
  */
-export async function buildClientNip94Pairs(file: File, url: string): Promise<string[][]> {
+export async function buildClientNip94Pairs(
+  file: File,
+  url: string,
+  videoPreview?: VideoNip94PreviewResult | null
+): Promise<string[][]> {
   const pairs: string[][] = [['url', url]]
 
   const mime = guessMimeFromFile(file)
@@ -217,10 +334,20 @@ export async function buildClientNip94Pairs(file: File, url: string): Promise<st
       }
     }
   } else if (mime?.startsWith('video/')) {
-    const dim = await videoDimensionsFromFile(file)
+    let vp = videoPreview
+    if (!vp) {
+      vp = await extractVideoNip94Preview(file)
+    }
+    const dim =
+      vp && vp.width > 0 && vp.height > 0
+        ? { width: vp.width, height: vp.height }
+        : await videoDimensionsFromFile(file)
     if (dim) {
       pairs.push(['dim', `${dim.width}x${dim.height}`])
     }
+    if (vp?.blurhash) {
+      pairs.push(['blurhash', vp.blurhash])
+    }
   }
 
   return pairs
diff --git a/src/services/media-upload.service.ts b/src/services/media-upload.service.ts
index c9222cac..7120558a 100644
--- a/src/services/media-upload.service.ts
+++ b/src/services/media-upload.service.ts
@@ -1,8 +1,10 @@
 /** Compression runs entirely in-app before upload (`compress-upload-media`). */
 import { compressMediaForUpload } from '@/lib/compress-upload-media'
 import { fetchWithTimeout } from '@/lib/fetch-with-timeout'
+import logger from '@/lib/logger'
 import {
   buildClientNip94Pairs,
+  extractVideoNip94Preview,
   mergeNip94Pairs,
   nip94PairsToImetaTag
 } from '@/lib/upload-nip94-imeta'
@@ -87,14 +89,32 @@ class MediaUploadService {
       // ignore
     }
 
-    let result: { url: string; tags: string[][] }
-    if (this.serviceConfig.type === 'nip96') {
-      result = await this.uploadByNip96(this.serviceConfig.service, toUpload, options)
-    } else {
-      result = await this.uploadByBlossom(toUpload, options)
+    const videoPreviewPromise =
+      toUpload.type.startsWith('video/') ? extractVideoNip94Preview(toUpload) : Promise.resolve(null)
+
+    const uploadPromise =
+      this.serviceConfig.type === 'nip96'
+        ? this.uploadByNip96(this.serviceConfig.service, toUpload, options)
+        : this.uploadByBlossom(toUpload, options)
+
+    const [videoPreview, result] = await Promise.all([videoPreviewPromise, uploadPromise])
+
+    const clientPairs = await buildClientNip94Pairs(toUpload, result.url, videoPreview)
+
+    if (videoPreview?.posterJpeg) {
+      try {
+        const posterResult =
+          this.serviceConfig.type === 'nip96'
+            ? await this.uploadByNip96(this.serviceConfig.service, videoPreview.posterJpeg, options)
+            : await this.uploadByBlossom(videoPreview.posterJpeg, options)
+        clientPairs.push(['image', posterResult.url], ['thumb', posterResult.url])
+      } catch (e) {
+        logger.warn('Video poster frame upload failed; imeta may omit image/thumb', {
+          error: String(e)
+        })
+      }
     }
 
-    const clientPairs = await buildClientNip94Pairs(toUpload, result.url)
     const mergedTags = mergeNip94Pairs(clientPairs, result.tags)
     this.imetaTagMap.set(result.url, nip94PairsToImetaTag(mergedTags))
     return { url: result.url, tags: mergedTags }