fix: file viewer opens audio/svg/binary like the attachments viewer

The File Browser preview and Attachments preview share openFilePreview(),
but the workspace branch (via /file-content) misclassified several types the
attachments viewer handled fine:

- SVG was reported as type:image, but file-raw serves SVG as octet-stream +
  attachment (XSS hardening), so the <img> broke. Now fetched and rendered via
  a same-origin image/svg+xml blob <img> (safe; <img> never runs SVG scripts).
  file-raw's SVG hardening is unchanged.
- Audio (mp3/wav/ogg/m4a/aac/flac/opus) was type:binary -> "Cannot preview".
  Now classified as audio and rendered with <audio controls>; file-raw gained
  the matching audio/video MIME types so playback works.
- Binary formats not in the hardcoded list (xlsx/doc/zip/...) were decoded as
  UTF-8 and dumped as mojibake. Replaced the static list with a NUL-byte
  content sniff that flags arbitrary binaries; the binary fallback now offers a
  Download link instead of dead-ending.

Adds route tests for audio, known-binary (xlsx), and NUL-sniff classification.
Verified end-to-end on an isolated instance + headless browser.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/web/public/panels-ui.js

@@ -2503,6 +2503,25 @@ Object.assign(CodemanApp.prototype, {
       bodyEl.innerHTML = `<iframe src="${escapeHtml(rawSrc)}" title="${escapeHtml(filePath)}"></iframe>`;
       return;
     }
+    // SVG renders as an image, but file-raw deliberately serves SVG as an
+    // untrusted octet-stream attachment (XSS hardening), so a direct
+    // <img src=file-raw> would break. Fetch the bytes and render via a
+    // same-origin blob typed image/svg+xml — <img> never executes scripts in
+    // the referenced SVG, so this is safe while still rendering the graphic.
+    if (ext === 'svg') {
+      footerEl.textContent = 'SVG';
+      try {
+        const res = await fetch(`/api/sessions/${sessionId}/file-raw?path=${encodeURIComponent(filePath)}`);
+        if (!res.ok) throw new Error('Failed to load image');
+        const blobUrl = URL.createObjectURL(new Blob([await res.text()], { type: 'image/svg+xml' }));
+        bodyEl.innerHTML = `<img src="${blobUrl}" alt="${escapeHtml(filePath)}">`;
+        const img = bodyEl.querySelector('img');
+        if (img) img.onload = () => URL.revokeObjectURL(blobUrl);
+      } catch (err) {
+        bodyEl.innerHTML = `<div class="binary-message">Error: ${escapeHtml(err.message)}</div>`;
+      }
+      return;
+    }
 
     try {
       const res = await fetch(`/api/sessions/${sessionId}/file-content?path=${encodeURIComponent(filePath)}&lines=500`);
@@ -2519,8 +2538,12 @@ Object.assign(CodemanApp.prototype, {
       } else if (data.type === 'video') {
         bodyEl.innerHTML = `<video src="${data.url}" controls autoplay></video>`;
         footerEl.textContent = `${this.formatFileSize(data.size)} \u2022 ${data.extension}`;
+      } else if (data.type === 'audio') {
+        bodyEl.innerHTML = `<audio src="${data.url}" controls autoplay></audio>`;
+        footerEl.textContent = `${this.formatFileSize(data.size)} \u2022 ${data.extension}`;
       } else if (data.type === 'binary') {
-        bodyEl.innerHTML = `<div class="binary-message">Binary file (${this.formatFileSize(data.size)})<br>Cannot preview</div>`;
+        const downloadHref = `/api/sessions/${sessionId}/file-raw?path=${encodeURIComponent(filePath)}&download=true`;
+        bodyEl.innerHTML = `<div class="binary-message">Binary file (${this.formatFileSize(data.size)})<br>Cannot preview<br><a href="${escapeHtml(downloadHref)}" download>Download</a></div>`;
         footerEl.textContent = data.extension || 'binary';
       } else {
         // Text content

src/web/public/styles.css

@@ -7239,12 +7239,22 @@ kbd {
   max-height: 100%;
 }
 
+.file-preview-body audio {
+  display: block;
+  width: 90%;
+  margin: 2rem auto;
+}
+
 .file-preview-body .binary-message {
   padding: 2rem;
   text-align: center;
   color: var(--text-muted);
 }
 
+.file-preview-body .binary-message a {
+  color: var(--accent, #4ea1ff);
+}
+
 .file-preview-footer {
   padding: 0.35rem 0.75rem;
   font-size: 0.7rem;

src/web/routes/file-routes.ts

@@ -511,49 +511,73 @@ export function registerFileRoutes(app: FastifyInstance, ctx: SessionPort & Even
     try {
       const stat = await fs.stat(resolvedPath);
 
-      // Check if it's a binary/media file
+      // Classify by extension. Known media types render with a dedicated player;
+      // other known-binary types are flagged so the client offers a download
+      // affordance instead of trying to decode the bytes as text. Matches the
+      // breadth of formats the attachments viewer renders (image/audio/video/pdf)
+      // so the file viewer can open the same files.
       const ext = filePath.split('.').pop()?.toLowerCase() || '';
-      const binaryExts = new Set([
+      const imageExts = new Set(['png', 'jpg', 'jpeg', 'gif', 'webp', 'svg', 'bmp', 'ico']);
-        'png',
+      const videoExts = new Set(['mp4', 'webm', 'mov', 'm4v', 'ogv']);
-        'jpg',
+      const audioExts = new Set(['mp3', 'wav', 'ogg', 'oga', 'm4a', 'aac', 'flac', 'opus']);
-        'jpeg',
+      const otherBinaryExts = new Set([
-        'gif',
-        'webp',
-        'ico',
-        'svg',
-        'bmp',
-        'mp4',
-        'webm',
-        'mov',
-        'avi',
-        'mp3',
-        'wav',
-        'ogg',
         'pdf',
         'zip',
         'tar',
         'gz',
+        'bz2',
+        'xz',
+        '7z',
+        'rar',
         'exe',
         'dll',
         'so',
+        'dylib',
+        'bin',
+        'wasm',
+        'class',
+        'o',
+        'a',
         'woff',
         'woff2',
         'ttf',
         'eot',
+        'otf',
+        'xlsx',
+        'xls',
+        'doc',
+        'docx',
+        'ppt',
+        'pptx',
+        'odt',
+        'ods',
+        'odp',
+        'avi',
+        'mkv',
+        'wmv',
+        'flv',
       ]);
-      const imageExts = new Set(['png', 'jpg', 'jpeg', 'gif', 'webp', 'svg', 'bmp', 'ico']);
-      const videoExts = new Set(['mp4', 'webm', 'mov', 'avi']);
 
-      if (raw === 'true' || binaryExts.has(ext)) {
+      const mediaType = imageExts.has(ext)
-        // Return metadata for binary files
+        ? 'image'
+        : videoExts.has(ext)
+          ? 'video'
+          : audioExts.has(ext)
+            ? 'audio'
+            : null;
+
+      const fileRawUrl = `/api/sessions/${id}/file-raw?path=${encodeURIComponent(filePath)}`;
+
+      if (raw === 'true' || mediaType || otherBinaryExts.has(ext)) {
+        // Return metadata for media/binary files (no text body)
         return {
           success: true,
           data: {
             path: filePath,
             size: stat.size,
-            type: imageExts.has(ext) ? 'image' : videoExts.has(ext) ? 'video' : 'binary',
+            type: mediaType ?? 'binary',
             extension: ext,
-            url: `/api/sessions/${id}/file-raw?path=${encodeURIComponent(filePath)}`,
+            url: fileRawUrl,
           },
         };
       }
@@ -567,10 +591,39 @@ export function registerFileRoutes(app: FastifyInstance, ctx: SessionPort & Even
         );
       }
 
+      // Read as raw bytes so we can sniff for binary content before decoding. An
+      // unrecognized extension (none at all, or a format not listed above) that
+      // is actually binary would otherwise be dumped to the viewer as UTF-8
+      // mojibake; a NUL byte in the first 8KB is a reliable binary signal that
+      // (unlike a static extension list) catches arbitrary binary formats.
+      const fileBuffer = await fs.readFile(resolvedPath);
+      const buf = Buffer.isBuffer(fileBuffer) ? fileBuffer : Buffer.from(String(fileBuffer));
+      const sniffLength = Math.min(buf.length, 8192);
+      let looksBinary = false;
+      for (let i = 0; i < sniffLength; i++) {
+        if (buf[i] === 0) {
+          looksBinary = true;
+          break;
+        }
+      }
+
+      if (looksBinary) {
+        return {
+          success: true,
+          data: {
+            path: filePath,
+            size: stat.size,
+            type: 'binary',
+            extension: ext,
+            url: fileRawUrl,
+          },
+        };
+      }
+
       // Read text file with line limit (bounded to prevent DoS)
       const MAX_LINES_LIMIT = 10000;
       const maxLines = Math.min(parseInt(lines || '500', 10) || 500, MAX_LINES_LIMIT);
-      const content = await fs.readFile(resolvedPath, 'utf-8');
+      const content = buf.toString('utf-8');
       const allLines = content.split('\n');
       const truncatedContent = allLines.length > maxLines;
       const displayContent = truncatedContent ? allLines.slice(0, maxLines).join('\n') : content;
@@ -638,9 +691,16 @@ export function registerFileRoutes(app: FastifyInstance, ctx: SessionPort & Even
         mp4: 'video/mp4',
         webm: 'video/webm',
         mov: 'video/quicktime',
+        m4v: 'video/mp4',
+        ogv: 'video/ogg',
         mp3: 'audio/mpeg',
         wav: 'audio/wav',
         ogg: 'audio/ogg',
+        oga: 'audio/ogg',
+        opus: 'audio/ogg',
+        m4a: 'audio/mp4',
+        aac: 'audio/aac',
+        flac: 'audio/flac',
         pdf: 'application/pdf',
         json: 'application/json',
       };

test/routes/file-routes.test.ts

@@ -215,6 +215,50 @@ describe('file-routes', () => {
       expect(body.data.url).toContain('file-raw');
     });
 
+    it('returns audio metadata for audio files', async () => {
+      mockedStat.mockResolvedValue({ size: 2048 } as never);
+
+      const res = await harness.app.inject({
+        method: 'GET',
+        url: `/api/sessions/${harness.ctx._sessionId}/file-content?path=clip.mp3`,
+      });
+      expect(res.statusCode).toBe(200);
+      const body = JSON.parse(res.body);
+      expect(body.success).toBe(true);
+      expect(body.data.type).toBe('audio');
+      expect(body.data.url).toContain('file-raw');
+    });
+
+    it('flags known-binary extensions (e.g. xlsx) instead of dumping mojibake', async () => {
+      mockedStat.mockResolvedValue({ size: 4096 } as never);
+
+      const res = await harness.app.inject({
+        method: 'GET',
+        url: `/api/sessions/${harness.ctx._sessionId}/file-content?path=sheet.xlsx`,
+      });
+      expect(res.statusCode).toBe(200);
+      const body = JSON.parse(res.body);
+      expect(body.success).toBe(true);
+      expect(body.data.type).toBe('binary');
+      expect(body.data.content).toBeUndefined();
+    });
+
+    it('sniffs NUL bytes and flags binary content for unknown extensions', async () => {
+      const binary = Buffer.from([0x50, 0x4b, 0x03, 0x04, 0x00, 0x01, 0x02]);
+      mockedReadFile.mockResolvedValue(binary as never);
+      mockedStat.mockResolvedValue({ size: binary.length } as never);
+
+      const res = await harness.app.inject({
+        method: 'GET',
+        url: `/api/sessions/${harness.ctx._sessionId}/file-content?path=mystery.dat`,
+      });
+      expect(res.statusCode).toBe(200);
+      const body = JSON.parse(res.body);
+      expect(body.success).toBe(true);
+      expect(body.data.type).toBe('binary');
+      expect(body.data.content).toBeUndefined();
+    });
+
     it('rejects path traversal attempts', async () => {
       // realpathSync resolves the symlink to a path outside workingDir
       mockedRealpathSync.mockReturnValue('/etc/passwd' as never);