Merge PR #120: document attachment previews + thumbnails (COD-38)

Adds attachment cards with first-page thumbnails and inline document
previews (PDF/Office via pdftoppm + LibreOffice), plus review hardening
(converter concurrency limiter, bounded preview cache, fixed detected-doc
preview routing). See PR #120.

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

# Conflicts:
#	src/web/public/styles.css

src/document-conversion-limiter.ts

@@ -0,0 +1,67 @@
+/**
+ * @fileoverview Global concurrency limiter for spawning external document
+ * converters (pdftoppm / LibreOffice `soffice` / Word-COM `powershell.exe`).
+ *
+ * Without a cap, N simultaneous thumbnail/preview requests for *distinct*
+ * documents fork N converter processes at once — each held open for up to the
+ * multi-minute conversion timeout. That is a localhost resource-exhaustion
+ * (fork-bomb-shaped) vector: a handful of large PDFs detected at once can pin
+ * CPU and RAM. This module serializes converter spawns down to a small fixed
+ * pool; excess spawns queue (FIFO) until a slot frees. The in-flight cache in
+ * `document-preview-cache.ts` already de-dups *identical* inputs; this bounds
+ * the *distinct* case the cache can't.
+ *
+ * Permit accounting transfers the slot directly to the next waiter on release
+ * (rather than decrement-then-reacquire) so the active count can never exceed
+ * the cap even under interleaved async resumption.
+ *
+ * NOT re-entrant: never call `runWithConversionLimit` from inside a task that is
+ * already holding a slot — a nested acquire under a full pool would deadlock.
+ * The converter call sites only ever acquire once per request (the office path
+ * acquires for `soffice` and `pdftoppm` sequentially, not nested).
+ */
+
+/**
+ * Max converter processes allowed to run concurrently across the whole process.
+ * Override with CODEMAN_MAX_DOCUMENT_CONVERSIONS (clamped to >= 1).
+ */
+const MAX_CONCURRENT_DOCUMENT_CONVERSIONS = (() => {
+  const raw = Number(process.env.CODEMAN_MAX_DOCUMENT_CONVERSIONS);
+  return Number.isFinite(raw) && raw >= 1 ? Math.floor(raw) : 3;
+})();
+
+let active = 0;
+const waiters: Array<() => void> = [];
+
+/** Test/diagnostic hook: converters currently holding a slot. */
+export function getActiveConversionCount(): number {
+  return active;
+}
+
+function acquire(): Promise<void> {
+  if (active < MAX_CONCURRENT_DOCUMENT_CONVERSIONS) {
+    active++;
+    return Promise.resolve();
+  }
+  return new Promise<void>((resolve) => waiters.push(resolve));
+}
+
+function release(): void {
+  const next = waiters.shift();
+  if (next) {
+    // Hand the slot straight to the next waiter — `active` stays at the cap.
+    next();
+  } else {
+    active--;
+  }
+}
+
+/** Run `task` once a converter slot is free, releasing the slot afterward. */
+export async function runWithConversionLimit<T>(task: () => Promise<T>): Promise<T> {
+  await acquire();
+  try {
+    return await task();
+  } finally {
+    release();
+  }
+}

src/document-preview-cache.ts

@@ -0,0 +1,308 @@
+/**
+ * @fileoverview Shared disk cache for expensive Office document previews.
+ */
+
+import { createHash } from 'node:crypto';
+import { execFile } from 'node:child_process';
+import fs from 'node:fs/promises';
+import { tmpdir } from 'node:os';
+import { basename, dirname, extname, join } from 'node:path';
+import { pathToFileURL } from 'node:url';
+import { promisify } from 'node:util';
+import { runWithConversionLimit } from './document-conversion-limiter.js';
+
+const execFileAsync = promisify(execFile);
+
+const OFFICE_CONVERSION_TIMEOUT_MS = 5 * 60_000;
+const DOCUMENT_PREVIEW_CACHE_DIR = join(tmpdir(), 'codeman-document-preview-cache');
+/**
+ * Cap on persistent converted-PDF files kept in DOCUMENT_PREVIEW_CACHE_DIR.
+ * The cache key embeds the source mtime, so every edit to a doc orphans its
+ * prior PDF; without a cap the dir grows unbounded across long-running sessions.
+ * Override with CODEMAN_MAX_PREVIEW_CACHE_FILES (clamped to >= 1).
+ */
+const MAX_PREVIEW_CACHE_FILES = (() => {
+  const raw = Number(process.env.CODEMAN_MAX_PREVIEW_CACHE_FILES);
+  return Number.isFinite(raw) && raw >= 1 ? Math.floor(raw) : 100;
+})();
+function buildWordExportPdfScript(sourcePath: string, outputPath: string): string {
+  return `
+$ErrorActionPreference = "Stop"
+$source = ${toPowerShellSingleQuotedString(sourcePath)}
+$output = ${toPowerShellSingleQuotedString(outputPath)}
+$word = $null
+$doc = $null
+try {
+  $word = New-Object -ComObject Word.Application
+  $word.Visible = $false
+  $word.DisplayAlerts = 0
+  $doc = $word.Documents.Open($source)
+  $doc.ExportAsFixedFormat($output, 17)
+} finally {
+  if ($null -ne $doc) {
+    $doc.Close($false) | Out-Null
+    [System.Runtime.InteropServices.Marshal]::ReleaseComObject($doc) | Out-Null
+  }
+  if ($null -ne $word) {
+    $word.Quit() | Out-Null
+    [System.Runtime.InteropServices.Marshal]::ReleaseComObject($word) | Out-Null
+  }
+  [System.GC]::Collect()
+  [System.GC]::WaitForPendingFinalizers()
+}
+`.trim();
+}
+
+type OfficePreviewConverter = 'msword' | 'libreoffice';
+
+const inFlightOfficeConversions = new Map<string, Promise<string | null>>();
+
+export function clearDocumentPreviewCache(): void {
+  inFlightOfficeConversions.clear();
+}
+
+/**
+ * Best-effort LRU-ish eviction for the persistent converted-PDF cache: keeps at
+ * most MAX_PREVIEW_CACHE_FILES `*.pdf` files in `cacheDir`, deleting the oldest
+ * by mtime once over the cap. Never throws — a pruning failure must not fail the
+ * conversion that triggered it. Only `*.pdf` files are considered, so the
+ * transient `work-*` mkdtemp dirs are ignored.
+ */
+export async function pruneDocumentPreviewCache(cacheDir: string): Promise<void> {
+  try {
+    const entries = await fs.readdir(cacheDir);
+    const pdfs = entries.filter((name) => name.toLowerCase().endsWith('.pdf'));
+    if (pdfs.length <= MAX_PREVIEW_CACHE_FILES) return;
+
+    const stats = await Promise.all(
+      pdfs.map(async (name) => {
+        const fullPath = join(cacheDir, name);
+        try {
+          const stat = await fs.stat(fullPath);
+          return { fullPath, mtimeMs: stat.mtimeMs ?? 0 };
+        } catch {
+          return null;
+        }
+      })
+    );
+
+    const sorted = stats.filter((s): s is { fullPath: string; mtimeMs: number } => s !== null);
+    sorted.sort((a, b) => a.mtimeMs - b.mtimeMs); // oldest first
+    const toRemove = sorted.slice(0, Math.max(0, sorted.length - MAX_PREVIEW_CACHE_FILES));
+    await Promise.all(toRemove.map((entry) => fs.rm(entry.fullPath, { force: true }).catch(() => {})));
+  } catch {
+    // Best-effort: pruning must never break a conversion.
+  }
+}
+
+export async function getOfficePreviewPdfPath(filePath: string, extension: string): Promise<string | null> {
+  const ext = extension.toLowerCase().replace(/^\./, '');
+  if (ext !== 'docx' && ext !== 'pptx') return null;
+
+  let sourceStat;
+  try {
+    sourceStat = await fs.stat(filePath);
+  } catch {
+    return null;
+  }
+
+  for (const converter of getOfficePreviewConverters(filePath, ext)) {
+    const cacheKey = createDocumentPreviewCacheKey(filePath, ext, sourceStat.size, sourceStat.mtimeMs ?? 0, converter);
+    const cachePath = getOfficePreviewCachePath(filePath, cacheKey, converter);
+
+    if (await fileExists(cachePath)) {
+      return cachePath;
+    }
+
+    const inFlightKey = `${converter}:${cacheKey}`;
+    const inFlight = inFlightOfficeConversions.get(inFlightKey);
+    if (inFlight) {
+      const converted = await inFlight;
+      if (converted) return converted;
+      continue;
+    }
+
+    const conversion =
+      converter === 'msword'
+        ? convertWordDocumentToCachedPdf(filePath, cachePath)
+        : convertLibreOfficeDocumentToCachedPdf(filePath, cachePath);
+    inFlightOfficeConversions.set(inFlightKey, conversion);
+    try {
+      const converted = await conversion;
+      if (converted) return converted;
+    } finally {
+      inFlightOfficeConversions.delete(inFlightKey);
+    }
+  }
+
+  return null;
+}
+
+function getOfficePreviewConverters(filePath: string, extension: string): OfficePreviewConverter[] {
+  if (extension === 'docx' && wslMountPathToWindowsPath(filePath)) {
+    return ['msword', 'libreoffice'];
+  }
+  return ['libreoffice'];
+}
+
+function createDocumentPreviewCacheKey(
+  filePath: string,
+  extension: string,
+  size: number,
+  mtimeMs: number,
+  converter: OfficePreviewConverter
+): string {
+  return createHash('sha256')
+    .update(JSON.stringify({ cacheVersion: 2, converter, filePath, extension, size, mtimeMs }))
+    .digest('hex')
+    .slice(0, 32);
+}
+
+function getOfficePreviewCachePath(filePath: string, cacheKey: string, converter: OfficePreviewConverter): string {
+  if (converter === 'msword') {
+    const windowsCacheDir = getWindowsUserTempCacheDir(filePath);
+    if (windowsCacheDir) {
+      return join(windowsCacheDir, `${cacheKey}.pdf`);
+    }
+  }
+
+  return join(DOCUMENT_PREVIEW_CACHE_DIR, `${cacheKey}.pdf`);
+}
+
+async function fileExists(filePath: string): Promise<boolean> {
+  try {
+    const stat = await fs.stat(filePath);
+    return typeof stat.isFile !== 'function' || stat.isFile();
+  } catch {
+    return false;
+  }
+}
+
+async function convertWordDocumentToCachedPdf(filePath: string, cachePath: string): Promise<string | null> {
+  const outputPath = wslMountPathToWindowsPath(cachePath);
+  if (!outputPath) return null;
+
+  let sourceCopyPath: string | undefined;
+
+  try {
+    await fs.mkdir(dirname(cachePath), { recursive: true });
+    sourceCopyPath = join(dirname(cachePath), `${basename(cachePath, '.pdf')}.docx`);
+    await fs.copyFile(filePath, sourceCopyPath);
+
+    const sourcePath = wslMountPathToWindowsPath(sourceCopyPath);
+    if (!sourcePath) return null;
+
+    await runWithConversionLimit(() =>
+      execFileAsync(
+        'powershell.exe',
+        [
+          '-NoProfile',
+          '-NonInteractive',
+          '-ExecutionPolicy',
+          'Bypass',
+          '-EncodedCommand',
+          encodePowerShellCommand(buildWordExportPdfScript(sourcePath, outputPath)),
+        ],
+        {
+          timeout: OFFICE_CONVERSION_TIMEOUT_MS,
+          maxBuffer: 1024 * 1024,
+        }
+      )
+    );
+
+    if (await fileExists(cachePath)) {
+      await pruneDocumentPreviewCache(dirname(cachePath));
+      return cachePath;
+    }
+
+    console.warn(`[DocumentPreviewCache] Microsoft Word did not produce PDF output for ${filePath}`);
+    return null;
+  } catch (err) {
+    console.warn(
+      `[DocumentPreviewCache] Failed to convert DOCX with Microsoft Word (${filePath}):`,
+      getCacheErrorMessage(err)
+    );
+    return null;
+  } finally {
+    if (sourceCopyPath) {
+      await fs.rm(sourceCopyPath, { force: true }).catch(() => {});
+    }
+  }
+}
+
+async function convertLibreOfficeDocumentToCachedPdf(filePath: string, cachePath: string): Promise<string | null> {
+  let workDir: string | undefined;
+  try {
+    await fs.mkdir(DOCUMENT_PREVIEW_CACHE_DIR, { recursive: true });
+    const outDir = await fs.mkdtemp(join(DOCUMENT_PREVIEW_CACHE_DIR, 'work-'));
+    workDir = outDir;
+    const profileDir = join(outDir, 'profile');
+    await fs.mkdir(profileDir, { recursive: true });
+
+    await runWithConversionLimit(() =>
+      execFileAsync(
+        'soffice',
+        [
+          '--headless',
+          '--nologo',
+          '--nofirststartwizard',
+          `-env:UserInstallation=${pathToFileURL(profileDir).href}`,
+          '--convert-to',
+          'pdf',
+          '--outdir',
+          outDir,
+          filePath,
+        ],
+        {
+          timeout: OFFICE_CONVERSION_TIMEOUT_MS,
+          maxBuffer: 1024 * 1024,
+        }
+      )
+    );
+
+    const converted = (await fs.readdir(outDir)).find((name) => name.toLowerCase().endsWith('.pdf'));
+    if (!converted) return null;
+
+    await fs.rename(join(workDir, converted), cachePath);
+    await pruneDocumentPreviewCache(DOCUMENT_PREVIEW_CACHE_DIR);
+    return cachePath;
+  } catch (err) {
+    console.warn(
+      `[DocumentPreviewCache] Failed to convert Office file to PDF (${filePath}):`,
+      getCacheErrorMessage(err)
+    );
+    return null;
+  } finally {
+    if (workDir) {
+      await fs.rm(workDir, { recursive: true, force: true }).catch(() => {});
+    }
+  }
+}
+
+function wslMountPathToWindowsPath(filePath: string): string | null {
+  const match = filePath.match(/^\/mnt\/([a-zA-Z])\/(.+)$/);
+  if (!match) return null;
+  return `${match[1].toUpperCase()}:\\${match[2].replace(/\//g, '\\')}`;
+}
+
+function getWindowsUserTempCacheDir(filePath: string): string | null {
+  const match = filePath.match(/^\/mnt\/([a-zA-Z])\/Users\/([^/]+)\//);
+  if (!match) return null;
+  return `/mnt/${match[1].toLowerCase()}/Users/${match[2]}/AppData/Local/Temp/codeman-document-preview-cache`;
+}
+
+function toPowerShellSingleQuotedString(value: string): string {
+  return `'${value.replace(/'/g, "''")}'`;
+}
+
+function encodePowerShellCommand(script: string): string {
+  return Buffer.from(script, 'utf16le').toString('base64');
+}
+
+export function getPreviewPdfDownloadName(fileName: string, extension: string): string {
+  return `${basename(fileName, extname(fileName) || `.${extension}`)}.pdf`;
+}
+
+function getCacheErrorMessage(err: unknown): string {
+  return err instanceof Error ? err.message : String(err);
+}

src/document-thumbnailer.ts

@@ -0,0 +1,88 @@
+/**
+ * @fileoverview Best-effort first-page thumbnails for attachment cards.
+ */
+
+import { execFile } from 'node:child_process';
+import fs from 'node:fs/promises';
+import { tmpdir } from 'node:os';
+import { basename, extname, join } from 'node:path';
+import { promisify } from 'node:util';
+import { getOfficePreviewPdfPath } from './document-preview-cache.js';
+import { runWithConversionLimit } from './document-conversion-limiter.js';
+
+const execFileAsync = promisify(execFile);
+const THUMBNAIL_CONVERSION_TIMEOUT_MS = 5 * 60_000;
+
+export interface ThumbnailResult {
+  content: Buffer;
+  contentType: 'image/png';
+}
+
+export async function generateFirstPageThumbnail(filePath: string, extension: string): Promise<ThumbnailResult | null> {
+  const ext = extension.toLowerCase().replace(/^\./, '');
+
+  try {
+    await fs.stat(filePath);
+
+    if (ext === 'png') {
+      return { content: await fs.readFile(filePath), contentType: 'image/png' };
+    }
+
+    if (ext === 'pdf') {
+      return renderPdfFirstPage(filePath);
+    }
+
+    if (ext === 'docx' || ext === 'pptx') {
+      return renderOfficeFirstPage(filePath);
+    }
+  } catch (err) {
+    console.warn(`[Thumbnailer] Failed to generate ${ext} thumbnail for ${filePath}:`, getThumbnailErrorMessage(err));
+    return null;
+  }
+
+  return null;
+}
+
+async function renderOfficeFirstPage(filePath: string): Promise<ThumbnailResult | null> {
+  try {
+    const previewPdfPath = await getOfficePreviewPdfPath(filePath, extname(filePath).toLowerCase().replace(/^\./, ''));
+    if (!previewPdfPath) return null;
+    return await renderPdfFirstPage(previewPdfPath);
+  } catch (err) {
+    console.warn(
+      `[Thumbnailer] Failed to convert Office file to PDF for thumbnail (${filePath}):`,
+      getThumbnailErrorMessage(err)
+    );
+    return null;
+  }
+}
+
+async function renderPdfFirstPage(filePath: string): Promise<ThumbnailResult | null> {
+  let previewDir: string | undefined;
+  try {
+    previewDir = await fs.mkdtemp(join(tmpdir(), 'codeman-thumb-pdf-'));
+    const prefix = join(previewDir, basename(filePath, extname(filePath)));
+    await runWithConversionLimit(() =>
+      execFileAsync('pdftoppm', ['-png', '-singlefile', '-f', '1', '-l', '1', '-scale-to', '520', filePath, prefix], {
+        timeout: THUMBNAIL_CONVERSION_TIMEOUT_MS,
+        maxBuffer: 1024 * 1024,
+      })
+    );
+    const content = await fs.readFile(`${prefix}.png`);
+    return { content, contentType: 'image/png' };
+  } catch (err) {
+    console.warn(
+      `[Thumbnailer] Failed to render PDF first page for thumbnail (${filePath}):`,
+      getThumbnailErrorMessage(err)
+    );
+    return null;
+  } finally {
+    if (previewDir) {
+      await fs.rm(previewDir, { recursive: true, force: true }).catch(() => {});
+    }
+  }
+}
+
+function getThumbnailErrorMessage(err: unknown): string {
+  return err instanceof Error ? err.message : String(err);
+}

src/image-watcher.ts

@@ -20,12 +20,8 @@ import { KeyedDebouncer } from './utils/index.js';
 // ========== Constants ==========
 
 /** Supported image file extensions (lowercase) */
-// PNG stays on the image-popup path: it's the dominant screenshot format and the
+const IMAGE_POPUP_EXTENSIONS = new Set(['.jpg', '.jpeg', '.gif', '.webp', '.bmp', '.svg']);
-// frontend only wires the `image:detected` popup today. The attachment-card UI
+const ATTACHMENT_EXTENSIONS = new Set(['.png', '.pdf', '.docx', '.pptx']);
-// that would consume `attachment:detected` for images is out of scope for this
-// PR, so routing PNG to it would silently break the dropped-screenshot popup.
-const IMAGE_POPUP_EXTENSIONS = new Set(['.png', '.jpg', '.jpeg', '.gif', '.webp', '.bmp', '.svg']);
-const ATTACHMENT_EXTENSIONS = new Set(['.pdf', '.docx', '.pptx']);
 const DETECTED_FILE_EXTENSIONS = new Set([...IMAGE_POPUP_EXTENSIONS, ...ATTACHMENT_EXTENSIONS]);
 
 /** Time to wait for file writes to stabilize (ms) */

src/web/public/app.js

@@ -223,6 +223,7 @@ const _SSE_HANDLER_MAP = [
 
   // Images
   [SSE_EVENTS.IMAGE_DETECTED, '_onImageDetected'],
+  [SSE_EVENTS.ATTACHMENT_DETECTED, '_onAttachmentDetected'],
 
   // Tunnel
   [SSE_EVENTS.TUNNEL_STARTED, '_onTunnelStarted'],
@@ -387,6 +388,8 @@ class CodemanApp {
     // Image popup windows (auto-open for detected screenshots/images)
     this.imagePopups = new Map(); // Map<imageId, { element, sessionId, filePath }>
     this.imagePopupZIndex = ZINDEX_IMAGE_POPUP_BASE;
+    this.attachmentCards = new Map(); // Map<attachmentId, { element, sessionId, filePath }>
+    this.attachmentCardStack = null;
 
     // File browser state (methods in panels-ui.js)
     this.fileBrowserData = null;
@@ -3596,6 +3599,7 @@ class CodemanApp {
     this.clearCountdownTimers(sessionId);
     this.closeSessionLogViewerWindows(sessionId);
     this.closeSessionImagePopups(sessionId);
+    this.closeSessionAttachmentCards(sessionId);
     this.closeSessionSubagentWindows(sessionId, true);
 
     // Clean up idle timer

src/web/public/panels-ui.js

@@ -2443,8 +2443,8 @@ Object.assign(CodemanApp.prototype, {
     this.saveAppSettingsToStorage(settings);
   },
 
-  async openFilePreview(filePath) {
+  async openFilePreview(filePath, sessionId = this.activeSessionId, attachmentId = null) {
-    if (!this.activeSessionId || !filePath) return;
+    if (!sessionId || !filePath) return;
 
     const overlay = this.$('filePreviewOverlay');
     const titleEl = this.$('filePreviewTitle');
@@ -2459,8 +2459,53 @@ Object.assign(CodemanApp.prototype, {
     bodyEl.innerHTML = '<div class="binary-message">Loading...</div>';
     footerEl.textContent = '';
 
+    const ext = (filePath.split('.').pop() || '').toLowerCase();
+
+    // Registered attachment: render straight from its by-id routes — images and
+    // PDFs inline, Office docs via the server-converted PDF preview, text fetched
+    // raw. (Workspace-path previews fall through to the file-content endpoint.)
+    if (attachmentId) {
+      const base = `/api/sessions/${sessionId}/attachments/${encodeURIComponent(attachmentId)}`;
+      const IMAGE_EXTS = new Set(['png', 'jpg', 'jpeg', 'gif', 'webp', 'bmp', 'svg']);
+      footerEl.textContent = ext.toUpperCase();
+      if (IMAGE_EXTS.has(ext)) {
+        bodyEl.innerHTML = `<img src="${escapeHtml(`${base}/raw`)}" alt="${escapeHtml(filePath)}">`;
+      } else if (ext === 'pdf') {
+        bodyEl.innerHTML = `<iframe src="${escapeHtml(`${base}/raw`)}" title="${escapeHtml(filePath)}"></iframe>`;
+      } else if (ext === 'docx' || ext === 'pptx') {
+        bodyEl.innerHTML = `<iframe src="${escapeHtml(`${base}/preview`)}" title="${escapeHtml(filePath)}"></iframe>`;
+      } else {
+        try {
+          const res = await fetch(`${base}/raw`);
+          if (!res.ok) throw new Error('Failed to load attachment');
+          const text = await res.text();
+          bodyEl.innerHTML = `<pre><code>${escapeHtml(text)}</code></pre>`;
+        } catch (err) {
+          bodyEl.innerHTML = `<div class="binary-message">Error: ${escapeHtml(err.message)}</div>`;
+        }
+      }
+      return;
+    }
+
+    // Workspace-path (auto-detected, unregistered) attachments: Office docs are
+    // converted to PDF server-side via the file-preview route; PDFs stream raw.
+    // Both render inline in an iframe. Without this, docx/pptx/pdf fall through
+    // to file-content below, which would dump the binary bytes as mojibake.
+    if (ext === 'docx' || ext === 'pptx') {
+      footerEl.textContent = ext.toUpperCase();
+      const previewSrc = `/api/sessions/${sessionId}/file-preview?path=${encodeURIComponent(filePath)}`;
+      bodyEl.innerHTML = `<iframe src="${escapeHtml(previewSrc)}" title="${escapeHtml(filePath)}"></iframe>`;
+      return;
+    }
+    if (ext === 'pdf') {
+      footerEl.textContent = 'PDF';
+      const rawSrc = `/api/sessions/${sessionId}/file-raw?path=${encodeURIComponent(filePath)}`;
+      bodyEl.innerHTML = `<iframe src="${escapeHtml(rawSrc)}" title="${escapeHtml(filePath)}"></iframe>`;
+      return;
+    }
+
     try {
-      const res = await fetch(`/api/sessions/${this.activeSessionId}/file-content?path=${encodeURIComponent(filePath)}&lines=500`);
+      const res = await fetch(`/api/sessions/${sessionId}/file-content?path=${encodeURIComponent(filePath)}&lines=500`);
       if (!res.ok) throw new Error('Failed to load file');
 
       const result = await res.json();
@@ -2498,6 +2543,183 @@ Object.assign(CodemanApp.prototype, {
     this.filePreviewContent = '';
   },
 
+  // ═══════════════════════════════════════════════════════════════
+  // Attachment Cards (detected documents/images)
+  // ═══════════════════════════════════════════════════════════════
+
+  // SSE `attachment:detected` consumer: surface a dismissible card for the file.
+  _onAttachmentDetected(data) {
+    console.log('[Attachment Detected]', data);
+    this.addAttachmentCard(data);
+  },
+
+  // Lazily create the floating stack the cards live in (appended to <body>).
+  ensureAttachmentCardStack() {
+    let stack = this.attachmentCardStack || document.getElementById('attachmentCardStack');
+    if (!stack) {
+      stack = document.createElement('div');
+      stack.id = 'attachmentCardStack';
+      stack.className = 'attachment-card-stack';
+      document.body.appendChild(stack);
+    }
+    this.attachmentCardStack = stack;
+    return stack;
+  },
+
+  openAttachmentInNewTab(sessionId, filePath, attachmentId = null) {
+    const url = attachmentId
+      ? `/api/sessions/${sessionId}/attachments/${encodeURIComponent(attachmentId)}/raw`
+      : `/api/sessions/${sessionId}/file-raw?path=${encodeURIComponent(filePath)}`;
+    window.open(url, '_blank');
+  },
+
+  addAttachmentCard(attachmentEvent) {
+    const {
+      sessionId,
+      relativePath,
+      fileName,
+      timestamp,
+      size,
+      attachmentType,
+      extension,
+      attachmentId,
+      rawUrl,
+      previewUrl,
+      thumbnailUrl,
+    } = attachmentEvent;
+    const filePath = relativePath || fileName;
+    const cardId = attachmentId || `${sessionId}-${timestamp}-${fileName}`;
+
+    if (this.attachmentCards.has(cardId)) {
+      const existing = this.attachmentCards.get(cardId);
+      existing.element.focus?.();
+      return;
+    }
+
+    const MAX_ATTACHMENT_CARDS = 10;
+    if (this.attachmentCards.size >= MAX_ATTACHMENT_CARDS) {
+      const oldestId = this.attachmentCards.keys().next().value;
+      if (oldestId) this.closeAttachmentCard(oldestId);
+    }
+
+    const stack = this.ensureAttachmentCardStack();
+    const session = this.sessions.get(sessionId);
+    const sessionName = session?.name || sessionId.substring(0, 8);
+    const attachmentRawUrl =
+      rawUrl ||
+      (attachmentId
+        ? `/api/sessions/${sessionId}/attachments/${encodeURIComponent(attachmentId)}/raw`
+        : `/api/sessions/${sessionId}/file-raw?path=${encodeURIComponent(filePath)}`);
+    const attachmentPreviewUrl =
+      previewUrl ||
+      (attachmentId ? `/api/sessions/${sessionId}/attachments/${encodeURIComponent(attachmentId)}/preview` : null);
+    const attachmentThumbnailUrl =
+      thumbnailUrl ||
+      (attachmentId
+        ? `/api/sessions/${sessionId}/attachments/${encodeURIComponent(attachmentId)}/thumbnail`
+        : `/api/sessions/${sessionId}/file-thumbnail?path=${encodeURIComponent(filePath)}`);
+    const downloadUrl = attachmentId ? `${attachmentRawUrl}?download=true` : `${attachmentRawUrl}&download=true`;
+    const typeLabel = (extension || attachmentType || 'file').toUpperCase();
+
+    const card = document.createElement('article');
+    card.className = `attachment-card attachment-${escapeHtml(attachmentType || 'file')}`;
+    card.tabIndex = 0;
+    card.dataset.attachmentId = cardId;
+    card.dataset.previewUrl = attachmentPreviewUrl || '';
+    card.innerHTML = `
+      <div class="attachment-thumbnail">
+        ${attachmentThumbnailUrl ? `<img class="attachment-thumbnail-img" src="${escapeHtml(attachmentThumbnailUrl)}" alt="">` : ''}
+        <div class="attachment-thumbnail-fallback ${attachmentThumbnailUrl ? '' : 'visible'}">${escapeHtml(typeLabel)}</div>
+      </div>
+      <div class="attachment-card-main">
+        <div class="attachment-file-name" title="${escapeHtml(filePath)}">${escapeHtml(fileName)}</div>
+        <div class="attachment-file-meta">
+          <span>${escapeHtml(sessionName)}</span>
+          <span>${this.formatFileSize(size || 0)}</span>
+        </div>
+        <div class="attachment-actions">
+          <button type="button" class="attachment-preview-btn">Preview</button>
+          <a href="${escapeHtml(downloadUrl)}">Download</a>
+          <button type="button" class="attachment-open-btn">Open</button>
+        </div>
+      </div>
+      <button type="button" class="attachment-close-btn" title="Dismiss">&times;</button>
+    `;
+
+    const attachmentThumbnailImg = card.querySelector('.attachment-thumbnail-img');
+    if (attachmentThumbnailImg) {
+      attachmentThumbnailImg.onerror = () => {
+        attachmentThumbnailImg.remove();
+        card.querySelector('.attachment-thumbnail-fallback')?.classList.add('visible');
+      };
+    }
+
+    card.querySelector('.attachment-preview-btn')?.addEventListener('click', () => {
+      this.openFilePreview(filePath, sessionId, attachmentId || null);
+    });
+    card.querySelector('.attachment-open-btn')?.addEventListener('click', () => {
+      this.openAttachmentInNewTab(sessionId, filePath, attachmentId || null);
+    });
+    card.querySelector('.attachment-close-btn')?.addEventListener('click', () => {
+      this.closeAttachmentCard(cardId);
+    });
+
+    stack.prepend(card);
+    this.attachmentCards.set(cardId, { element: card, sessionId, filePath });
+    this._refreshAttachmentClearAll();
+  },
+
+  // Centralized show/hide for the stack's "Clear all" control. Both addAttachmentCard and
+  // closeAttachmentCard call this so the control appears on the 2nd card and hides at <=1.
+  _refreshAttachmentClearAll() {
+    const stack = this.attachmentCardStack;
+    if (!stack) return;
+    let control = stack.querySelector('.attachment-clear-all');
+    if (this.attachmentCards.size < 2) {
+      if (control) control.hidden = true;
+      return;
+    }
+    if (!control) {
+      control = document.createElement('button');
+      control.type = 'button';
+      control.className = 'attachment-clear-all';
+      control.textContent = 'Clear all';
+      control.title = 'Dismiss all attachment cards';
+      control.addEventListener('click', () => this.closeAllAttachmentCards());
+      stack.prepend(control);
+    }
+    control.hidden = false;
+  },
+
+  closeAttachmentCard(attachmentId) {
+    const cardData = this.attachmentCards.get(attachmentId);
+    if (!cardData) return;
+    cardData.element.remove();
+    this.attachmentCards.delete(attachmentId);
+    if (this.attachmentCardStack && this.attachmentCards.size === 0) {
+      this.attachmentCardStack.remove();
+      this.attachmentCardStack = null;
+    } else {
+      this._refreshAttachmentClearAll();
+    }
+  },
+
+  closeAllAttachmentCards() {
+    for (const attachmentId of [...this.attachmentCards.keys()]) {
+      this.closeAttachmentCard(attachmentId);
+    }
+  },
+
+  closeSessionAttachmentCards(sessionId) {
+    const toClose = [];
+    for (const [attachmentId, data] of this.attachmentCards) {
+      if (data.sessionId === sessionId) toClose.push(attachmentId);
+    }
+    for (const attachmentId of toClose) {
+      this.closeAttachmentCard(attachmentId);
+    }
+  },
+
   copyFilePreviewContent() {
     if (this.filePreviewContent) {
       navigator.clipboard.writeText(this.filePreviewContent).then(() => {

src/web/public/styles.css

@@ -9232,6 +9232,175 @@ body.touch-device.cjk-input-visible .main {
   z-index: 100;
 }
 
+.attachment-card-stack {
+  position: fixed;
+  right: 18px;
+  bottom: calc(var(--toolbar-height) + 18px);
+  z-index: 1900;
+  display: flex;
+  flex-direction: column;
+  gap: 8px;
+  width: min(540px, calc(100vw - 32px));
+  pointer-events: none;
+}
+
+.attachment-clear-all {
+  align-self: flex-end;
+  padding: 3px 10px;
+  border: 1px solid var(--border-light);
+  border-radius: 5px;
+  background: rgba(19, 19, 22, 0.96);
+  color: var(--text-dim);
+  font-size: 0.68rem;
+  font-weight: 600;
+  cursor: pointer;
+  box-shadow: 0 8px 28px rgba(0, 0, 0, 0.35);
+  pointer-events: auto;
+}
+
+.attachment-clear-all:hover {
+  border-color: var(--accent);
+  color: var(--accent-hover);
+}
+
+.attachment-clear-all[hidden] {
+  display: none;
+}
+
+.attachment-card {
+  display: grid;
+  grid-template-columns: 96px minmax(0, 1fr) 24px;
+  gap: 10px;
+  align-items: center;
+  padding: 10px;
+  border: 1px solid rgba(255, 255, 255, 0.08);
+  border-radius: 8px;
+  background: rgba(19, 19, 22, 0.96);
+  box-shadow: 0 8px 28px rgba(0, 0, 0, 0.35);
+  pointer-events: auto;
+}
+
+.attachment-thumbnail {
+  position: relative;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  width: 96px;
+  height: auto;
+  aspect-ratio: 16 / 9;
+  overflow: hidden;
+  border-radius: 6px;
+  background: #f8f8fb;
+  border: 1px solid var(--border-light);
+}
+
+.attachment-thumbnail-img {
+  width: 100%;
+  height: 100%;
+  object-fit: contain;
+  object-position: center;
+  display: block;
+}
+
+.attachment-thumbnail-fallback {
+  display: none;
+  align-items: center;
+  justify-content: center;
+  position: absolute;
+  inset: 0;
+  color: var(--text);
+  font-size: 0.7rem;
+  font-weight: 700;
+  background: #20202a;
+}
+
+.attachment-thumbnail-fallback.visible {
+  display: flex;
+}
+
+.attachment-type-badge {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  width: 44px;
+  height: 44px;
+  border-radius: 6px;
+  background: #20202a;
+  color: var(--text);
+  border: 1px solid var(--border-light);
+  font-size: 0.7rem;
+  font-weight: 700;
+}
+
+.attachment-card-main {
+  min-width: 0;
+}
+
+.attachment-file-name {
+  color: var(--text);
+  font-size: 0.82rem;
+  font-weight: 600;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+.attachment-file-meta {
+  display: flex;
+  gap: 8px;
+  margin-top: 2px;
+  color: var(--text-dim);
+  font-size: 0.68rem;
+}
+
+.attachment-actions {
+  display: flex;
+  align-items: center;
+  gap: 6px;
+  margin-top: 7px;
+}
+
+.attachment-actions button,
+.attachment-actions a {
+  padding: 3px 8px;
+  border: 1px solid var(--border-light);
+  border-radius: 5px;
+  background: var(--bg-input);
+  color: var(--text);
+  text-decoration: none;
+  font-size: 0.68rem;
+  cursor: pointer;
+}
+
+.attachment-actions button:hover,
+.attachment-actions a:hover {
+  border-color: var(--accent);
+  color: var(--accent-hover);
+}
+
+.attachment-close-btn {
+  align-self: start;
+  width: 22px;
+  height: 22px;
+  border: none;
+  background: transparent;
+  color: var(--text-muted);
+  font-size: 1rem;
+  cursor: pointer;
+}
+
+.attachment-close-btn:hover {
+  color: var(--text);
+}
+
+/* PDF/Office previews render in an iframe inside the preview body. */
+.file-preview-body iframe {
+  width: 100%;
+  height: 100%;
+  border: 0;
+  background: #fff;
+}
+
 /* ============================================================
    === v1.0 Carbon Aurora · Daylight overrides ===
    Single appended block — trivially removable. Retones the hardcoded

src/web/routes/file-routes.ts

@@ -12,14 +12,17 @@ import { fileStreamManager } from '../../file-stream-manager.js';
 import {
   AttachmentRegistrationError,
   attachmentRegistry,
+  isSupportedAttachmentExtension,
   registerExternalAttachment,
   type AttachmentRecord,
 } from '../../attachment-registry.js';
+import { generateFirstPageThumbnail } from '../../document-thumbnailer.js';
+import { getOfficePreviewPdfPath, getPreviewPdfDownloadName } from '../../document-preview-cache.js';
 import { isBlockedAttachmentPath, loadAttachmentGuardConfig } from '../../config/attachment-guard.js';
 import { findSessionOrFail, validateSessionFilePath } from '../route-helpers.js';
 import { isSensitivePath } from '../sensitive-path.js';
 import { SseEvent } from '../sse-events.js';
-import type { EventPort, SessionPort } from '../ports/index.js';
+import type { ConfigPort, EventPort, SessionPort } from '../ports/index.js';
 
 const MIME_TYPES: Record<string, string> = {
   png: 'image/png',
@@ -159,7 +162,80 @@ async function resolveServableAttachmentPath(
   return resolved ? pathToCheck : record.filePath;
 }
 
-export function registerFileRoutes(app: FastifyInstance, ctx: SessionPort & EventPort): void {
+/**
+ * Convert a DOCX/PPTX to a single-PDF preview (LibreOffice when available) and
+ * stream it inline. PDF/PNG and text formats don't need conversion — callers
+ * redirect those to the raw route instead.
+ */
+async function serveConvertedPreview(
+  reply: FastifyReply,
+  resolvedPath: string,
+  fileName: string,
+  extension: string
+): Promise<void> {
+  if (extension !== 'docx' && extension !== 'pptx') {
+    reply
+      .code(400)
+      .send(createErrorResponse(ApiErrorCode.INVALID_INPUT, 'Preview is not supported for this file type'));
+    return;
+  }
+
+  try {
+    const previewPath = await getOfficePreviewPdfPath(resolvedPath, extension);
+    if (!previewPath) {
+      reply.code(500).send(createErrorResponse(ApiErrorCode.OPERATION_FAILED, 'Document preview conversion failed'));
+      return;
+    }
+
+    const content = await fs.readFile(previewPath);
+    reply.header('Content-Type', 'application/pdf');
+    reply.header('Content-Disposition', `inline; filename="${getPreviewPdfDownloadName(fileName, extension)}"`);
+    reply.header('Cache-Control', 'no-cache');
+    reply.header('Content-Length', content.length);
+    reply.header('X-Content-Type-Options', 'nosniff');
+    reply.send(content);
+  } catch (err) {
+    reply
+      .code(500)
+      .send(createErrorResponse(ApiErrorCode.OPERATION_FAILED, `Failed to generate preview: ${getErrorMessage(err)}`));
+  }
+}
+
+/** Generate and stream a first-page thumbnail (PNG) for a supported attachment. */
+async function serveThumbnail(reply: FastifyReply, resolvedPath: string, extension: string): Promise<void> {
+  const thumbnail = await generateFirstPageThumbnail(resolvedPath, extension);
+  if (!thumbnail) {
+    reply.code(204).send();
+    return;
+  }
+
+  reply.header('Content-Type', thumbnail.contentType);
+  reply.header('Cache-Control', 'no-cache');
+  reply.header('X-Content-Type-Options', 'nosniff');
+  reply.send(thumbnail.content);
+}
+
+/**
+ * Resolve a session's working dir from the live session, falling back to the
+ * persisted record so preview/thumbnail requests keep working for a session
+ * that has since detached. Sends a 404 and returns undefined when unknown.
+ */
+function getKnownSessionWorkingDir(
+  ctx: SessionPort & ConfigPort,
+  sessionId: string,
+  reply: FastifyReply
+): string | undefined {
+  const liveSession = ctx.sessions.get(sessionId);
+  if (liveSession) return liveSession.workingDir;
+
+  const stored = ctx.store.getSession(sessionId);
+  if (stored) return stored.workingDir;
+
+  reply.code(404).send(createErrorResponse(ApiErrorCode.NOT_FOUND, `Session ${sessionId} not found`));
+  return undefined;
+}
+
+export function registerFileRoutes(app: FastifyInstance, ctx: SessionPort & EventPort & ConfigPort): void {
   // File tree listing
   app.get('/api/sessions/:id/files', async (req) => {
     const { id } = req.params as { id: string };
@@ -515,6 +591,97 @@ export function registerFileRoutes(app: FastifyInstance, ctx: SessionPort & Even
     }
   });
 
+  // Serve a converted PDF preview of a registered attachment by id. Office docs
+  // convert server-side; PDF/PNG/text redirect to the raw route.
+  app.get('/api/sessions/:id/attachments/:attachmentId/preview', async (req, reply) => {
+    const { id, attachmentId } = req.params as { id: string; attachmentId: string };
+    const workingDir = getKnownSessionWorkingDir(ctx, id, reply);
+    if (!workingDir) return;
+    const record = getAttachmentOr404(reply, id, attachmentId);
+    if (!record) return;
+    const servePath = await resolveServableAttachmentPath(reply, record, workingDir);
+    if (!servePath) return;
+
+    // Only Office formats need server-side conversion; PDF/PNG and text formats
+    // (md/txt) preview directly from their raw bytes.
+    if (record.extension !== 'docx' && record.extension !== 'pptx') {
+      reply.redirect(`/api/sessions/${id}/attachments/${encodeURIComponent(attachmentId)}/raw`);
+      return;
+    }
+
+    await serveConvertedPreview(reply, servePath, record.fileName, record.extension);
+  });
+
+  // Serve a first-page thumbnail of a registered attachment by id.
+  app.get('/api/sessions/:id/attachments/:attachmentId/thumbnail', async (req, reply) => {
+    const { id, attachmentId } = req.params as { id: string; attachmentId: string };
+    const workingDir = getKnownSessionWorkingDir(ctx, id, reply);
+    if (!workingDir) return;
+    const record = getAttachmentOr404(reply, id, attachmentId);
+    if (!record) return;
+    const servePath = await resolveServableAttachmentPath(reply, record, workingDir);
+    if (!servePath) return;
+    await serveThumbnail(reply, servePath, record.extension);
+  });
+
+  // Serve converted document previews for a workspace-relative path. DOCX/PPTX
+  // are converted to PDF via LibreOffice; PDF/PNG/text preview through file-raw.
+  app.get('/api/sessions/:id/file-preview', async (req, reply) => {
+    const { id } = req.params as { id: string };
+    const { path: filePath } = req.query as { path?: string };
+    const workingDir = getKnownSessionWorkingDir(ctx, id, reply);
+    if (!workingDir) return;
+
+    if (!filePath) {
+      reply.code(400).send(createErrorResponse(ApiErrorCode.INVALID_INPUT, 'Missing path parameter'));
+      return;
+    }
+
+    const validated = validateSessionFilePath(workingDir, filePath);
+    if (!validated) {
+      reply.code(404).send(createErrorResponse(ApiErrorCode.NOT_FOUND, 'File not found'));
+      return;
+    }
+    const { resolvedPath } = validated;
+    const ext = filePath.split('.').pop()?.toLowerCase() || '';
+
+    if (ext !== 'docx' && ext !== 'pptx') {
+      reply.redirect(`/api/sessions/${id}/file-raw?path=${encodeURIComponent(filePath)}`);
+      return;
+    }
+
+    await serveConvertedPreview(reply, resolvedPath, filePath, ext);
+  });
+
+  // Serve a first-page thumbnail for a workspace-relative path.
+  app.get('/api/sessions/:id/file-thumbnail', async (req, reply) => {
+    const { id } = req.params as { id: string };
+    const { path: filePath } = req.query as { path?: string };
+    const workingDir = getKnownSessionWorkingDir(ctx, id, reply);
+    if (!workingDir) return;
+
+    if (!filePath) {
+      reply.code(400).send(createErrorResponse(ApiErrorCode.INVALID_INPUT, 'Missing path parameter'));
+      return;
+    }
+
+    const validated = validateSessionFilePath(workingDir, filePath);
+    if (!validated) {
+      reply.code(404).send(createErrorResponse(ApiErrorCode.NOT_FOUND, 'File not found'));
+      return;
+    }
+
+    const ext = filePath.split('.').pop()?.toLowerCase() || '';
+    if (!isSupportedAttachmentExtension(ext)) {
+      reply
+        .code(400)
+        .send(createErrorResponse(ApiErrorCode.INVALID_INPUT, 'Thumbnail is not supported for this file type'));
+      return;
+    }
+
+    await serveThumbnail(reply, validated.resolvedPath, ext);
+  });
+
   // Stream file content via tail -f (SSE endpoint)
   app.get('/api/sessions/:id/tail-file', async (req, reply) => {
     const { id } = req.params as { id: string };

src/web/server.ts

@@ -60,7 +60,7 @@ import {
   type SubagentToolResult,
 } from '../subagent-watcher.js';
 import { imageWatcher } from '../image-watcher.js';
-import { attachmentRegistry, registerExternalAttachment } from '../attachment-registry.js';
+import { attachmentRegistry, buildFileThumbnailRoute, registerExternalAttachment } from '../attachment-registry.js';
 import { TranscriptWatcher } from '../transcript-watcher.js';
 import { TeamWatcher } from '../team-watcher.js';
 import { TunnelManager } from '../tunnel-manager.js';
@@ -442,7 +442,12 @@ export class WebServer extends EventEmitter {
     this.imageWatcherHandlers = {
       detected: (event: ImageDetectedEvent) => this.broadcast(SseEvent.ImageDetected, event),
       attachmentDetected: (event: AttachmentDetectedEvent) =>
-        this.broadcast(SseEvent.AttachmentDetected, { ...event, source: event.source || 'detected' }),
+        this.broadcast(SseEvent.AttachmentDetected, {
+          ...event,
+          source: event.source || 'detected',
+          thumbnailUrl:
+            event.thumbnailUrl || buildFileThumbnailRoute(event.sessionId, event.relativePath || event.fileName),
+        }),
       error: (error: Error, sessionId?: string) => {
         console.error(`[ImageWatcher] Error${sessionId ? ` for ${sessionId}` : ''}:`, error.message);
       },

test/document-conversion-limiter.test.ts

@@ -0,0 +1,47 @@
+import { describe, it, expect } from 'vitest';
+import { runWithConversionLimit, getActiveConversionCount } from '../src/document-conversion-limiter.js';
+
+describe('document-conversion-limiter', () => {
+  it('never runs more converters than the cap (default 3) concurrently', async () => {
+    let running = 0;
+    let maxObserved = 0;
+
+    const task = () => async () => {
+      running++;
+      maxObserved = Math.max(maxObserved, running);
+      // The module's own accounting must also stay within the cap.
+      expect(getActiveConversionCount()).toBeLessThanOrEqual(3);
+      await new Promise((resolve) => setTimeout(resolve, 5));
+      running--;
+    };
+
+    await Promise.all(Array.from({ length: 12 }, () => runWithConversionLimit(task())));
+
+    expect(maxObserved).toBeLessThanOrEqual(3);
+    expect(maxObserved).toBeGreaterThan(1); // proves it genuinely parallelizes, not serializes
+    expect(getActiveConversionCount()).toBe(0); // every slot released
+  });
+
+  it('processes every queued task even when far more are submitted than the cap', async () => {
+    let completed = 0;
+    await Promise.all(
+      Array.from({ length: 25 }, () =>
+        runWithConversionLimit(async () => {
+          await new Promise((resolve) => setTimeout(resolve, 1));
+          completed++;
+        })
+      )
+    );
+    expect(completed).toBe(25);
+    expect(getActiveConversionCount()).toBe(0);
+  });
+
+  it('releases the slot when a task throws', async () => {
+    await expect(
+      runWithConversionLimit(async () => {
+        throw new Error('boom');
+      })
+    ).rejects.toThrow('boom');
+    expect(getActiveConversionCount()).toBe(0);
+  });
+});

test/document-preview-cache-eviction.test.ts

@@ -0,0 +1,55 @@
+import { describe, it, expect, beforeEach, vi } from 'vitest';
+import fs from 'node:fs/promises';
+import { pruneDocumentPreviewCache } from '../src/document-preview-cache.js';
+
+vi.mock('node:fs/promises', () => ({
+  default: {
+    readdir: vi.fn(),
+    stat: vi.fn(),
+    rm: vi.fn(async () => undefined),
+  },
+}));
+
+const mockedReaddir = vi.mocked(fs.readdir);
+const mockedStat = vi.mocked(fs.stat);
+const mockedRm = vi.mocked(fs.rm);
+
+describe('pruneDocumentPreviewCache', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    // mtime encoded in the filename (f0 oldest ... f101 newest)
+    mockedStat.mockImplementation(async (p) => {
+      const m = /f(\d+)\.pdf$/.exec(String(p));
+      return { mtimeMs: m ? Number(m[1]) : 0, isFile: () => true } as never;
+    });
+  });
+
+  it('evicts the oldest *.pdf files once the cache exceeds the cap (default 100)', async () => {
+    const names = Array.from({ length: 102 }, (_, i) => `f${i}.pdf`);
+    mockedReaddir.mockResolvedValue(names as never);
+
+    await pruneDocumentPreviewCache('/tmp/codeman-document-preview-cache');
+
+    // 102 - 100 = 2 oldest removed
+    expect(mockedRm).toHaveBeenCalledTimes(2);
+    const removed = mockedRm.mock.calls.map((c) => String(c[0]));
+    expect(removed.some((p) => p.endsWith('f0.pdf'))).toBe(true);
+    expect(removed.some((p) => p.endsWith('f1.pdf'))).toBe(true);
+    expect(removed.some((p) => p.endsWith('f101.pdf'))).toBe(false); // newest kept
+  });
+
+  it('ignores non-pdf entries (e.g. transient work-* dirs) when counting', async () => {
+    const names = [...Array.from({ length: 50 }, (_, i) => `f${i}.pdf`), 'work-abc', 'work-def'];
+    mockedReaddir.mockResolvedValue(names as never);
+
+    await pruneDocumentPreviewCache('/tmp/codeman-document-preview-cache');
+
+    expect(mockedRm).not.toHaveBeenCalled(); // 50 pdfs <= cap
+  });
+
+  it('never throws when the cache dir cannot be read', async () => {
+    mockedReaddir.mockRejectedValue(new Error('ENOENT'));
+    await expect(pruneDocumentPreviewCache('/tmp/missing')).resolves.toBeUndefined();
+    expect(mockedRm).not.toHaveBeenCalled();
+  });
+});

test/document-preview-cache.test.ts

@@ -0,0 +1,109 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+import { execFile } from 'node:child_process';
+import fs from 'node:fs/promises';
+import { clearDocumentPreviewCache, getOfficePreviewPdfPath } from '../src/document-preview-cache.js';
+
+vi.mock('node:child_process', () => ({
+  execFile: vi.fn((_cmd, _args, _options, callback) => {
+    setTimeout(() => callback(null, { stdout: '', stderr: '' }), 1);
+    return {};
+  }),
+}));
+
+vi.mock('node:fs/promises', () => ({
+  default: {
+    stat: vi.fn(),
+    mkdir: vi.fn(async () => undefined),
+    copyFile: vi.fn(async () => undefined),
+    mkdtemp: vi.fn(async () => '/tmp/codeman-document-preview-cache/work-test'),
+    readdir: vi.fn(async () => ['deck.pdf']),
+    rename: vi.fn(async () => undefined),
+    rm: vi.fn(async () => undefined),
+  },
+}));
+
+const mockedExecFile = vi.mocked(execFile);
+const mockedStat = vi.mocked(fs.stat);
+const mockedRename = vi.mocked(fs.rename);
+
+describe('document-preview-cache', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    clearDocumentPreviewCache();
+
+    let cachedPdfExists = false;
+    mockedStat.mockImplementation(async (path) => {
+      const pathText = String(path);
+      if (pathText.includes('codeman-document-preview-cache') && pathText.endsWith('.pdf')) {
+        if (!cachedPdfExists) throw new Error('ENOENT');
+        return { size: 4096, isFile: () => true } as never;
+      }
+
+      return { size: 1845494, mtimeMs: 12345, isFile: () => true } as never;
+    });
+    mockedRename.mockImplementation(async () => {
+      cachedPdfExists = true;
+    });
+    mockedExecFile.mockImplementation((cmd, _args, _options, callback) => {
+      if (cmd === 'powershell.exe') {
+        cachedPdfExists = true;
+      }
+
+      setTimeout(() => callback(null, { stdout: '', stderr: '' }), 1);
+      return {} as never;
+    });
+  });
+
+  it('deduplicates concurrent Office preview conversions and reuses the cached PDF', async () => {
+    const [firstPath, secondPath] = await Promise.all([
+      getOfficePreviewPdfPath('/tmp/deck.pptx', 'pptx'),
+      getOfficePreviewPdfPath('/tmp/deck.pptx', 'pptx'),
+    ]);
+    const thirdPath = await getOfficePreviewPdfPath('/tmp/deck.pptx', 'pptx');
+
+    expect(firstPath).toBeTruthy();
+    expect(secondPath).toBe(firstPath);
+    expect(thirdPath).toBe(firstPath);
+    expect(mockedExecFile).toHaveBeenCalledTimes(1);
+    expect(mockedExecFile).toHaveBeenCalledWith(
+      'soffice',
+      expect.arrayContaining([
+        '--headless',
+        '--convert-to',
+        'pdf',
+        expect.stringMatching(/^-env:UserInstallation=file:/),
+      ]),
+      expect.any(Object),
+      expect.any(Function)
+    );
+  });
+
+  it('prefers Microsoft Word for DOCX files on Windows-mounted paths', async () => {
+    const result = await getOfficePreviewPdfPath(
+      '/mnt/c/Users/aakhter/Documents/codeman-inline-viewer-test.docx',
+      'docx'
+    );
+
+    expect(result).toContain('/mnt/c/Users/aakhter/AppData/Local/Temp/codeman-document-preview-cache/');
+    expect(mockedExecFile).toHaveBeenCalledWith(
+      'powershell.exe',
+      expect.arrayContaining(['-NoProfile', '-NonInteractive', '-EncodedCommand']),
+      expect.any(Object),
+      expect.any(Function)
+    );
+    const powerShellCall = mockedExecFile.mock.calls.find(([cmd]) => cmd === 'powershell.exe');
+    const encodedCommand = powerShellCall?.[1]?.at(-1);
+    const decodedCommand = Buffer.from(String(encodedCommand), 'base64').toString('utf16le');
+    expect(decodedCommand).toContain('$source = ');
+    expect(decodedCommand).toContain('C:\\Users\\aakhter\\AppData\\Local\\Temp\\codeman-document-preview-cache\\');
+    expect(decodedCommand).toContain('.docx');
+    expect(decodedCommand).toContain('$output = ');
+    expect(decodedCommand).toContain('.pdf');
+    expect(mockedExecFile).not.toHaveBeenCalledWith(
+      'soffice',
+      expect.any(Array),
+      expect.any(Object),
+      expect.any(Function)
+    );
+  });
+});

test/document-thumbnailer.test.ts

@@ -0,0 +1,96 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+import { execFile } from 'node:child_process';
+import fs from 'node:fs/promises';
+import { generateFirstPageThumbnail } from '../src/document-thumbnailer.js';
+import { clearDocumentPreviewCache } from '../src/document-preview-cache.js';
+
+vi.mock('node:child_process', () => ({
+  execFile: vi.fn((_cmd, _args, _options, callback) => {
+    callback(null, { stdout: '', stderr: '' });
+    return {};
+  }),
+}));
+
+vi.mock('node:fs/promises', () => ({
+  default: {
+    stat: vi.fn(async () => ({ size: 100, isFile: () => true })),
+    readFile: vi.fn(async () => Buffer.from('png')),
+    readdir: vi.fn(async () => ['converted.pdf']),
+    mkdir: vi.fn(async () => undefined),
+    mkdtemp: vi.fn(async () => '/tmp/codeman-thumb-test'),
+    rename: vi.fn(async () => undefined),
+    rm: vi.fn(async () => undefined),
+  },
+}));
+
+const mockedExecFile = vi.mocked(execFile);
+const mockedStat = vi.mocked(fs.stat);
+const mockedReadFile = vi.mocked(fs.readFile);
+const mockedReaddir = vi.mocked(fs.readdir);
+const mockedMkdir = vi.mocked(fs.mkdir);
+const mockedMkdtemp = vi.mocked(fs.mkdtemp);
+const mockedRename = vi.mocked(fs.rename);
+const mockedRm = vi.mocked(fs.rm);
+
+describe('document-thumbnailer', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    clearDocumentPreviewCache();
+    mockedStat.mockImplementation(async (path) => {
+      const pathText = String(path);
+      if (pathText.includes('codeman-document-preview-cache') && pathText.endsWith('.pdf')) {
+        throw new Error('ENOENT');
+      }
+
+      return { size: 500 * 1024 * 1024, mtimeMs: 12345, isFile: () => true } as never;
+    });
+    mockedReadFile.mockResolvedValue(Buffer.from('large thumbnail') as never);
+    mockedReaddir.mockResolvedValue(['converted.pdf'] as never);
+    mockedMkdir.mockResolvedValue(undefined as never);
+    mockedMkdtemp.mockResolvedValue('/tmp/codeman-thumb-test' as never);
+    mockedRename.mockResolvedValue(undefined as never);
+    mockedRm.mockResolvedValue(undefined as never);
+    mockedExecFile.mockImplementation((_cmd, _args, _options, callback) => {
+      callback(null, { stdout: '', stderr: '' });
+      return {} as never;
+    });
+  });
+
+  it('renders first-page thumbnails for large documents without an app-level size cap', async () => {
+    const result = await generateFirstPageThumbnail('/tmp/large-deck.pdf', 'pdf');
+
+    expect(result).toEqual({
+      content: Buffer.from('large thumbnail'),
+      contentType: 'image/png',
+    });
+    expect(mockedExecFile).toHaveBeenCalledWith(
+      'pdftoppm',
+      expect.arrayContaining(['-png', '-singlefile', '-f', '1', '-l', '1']),
+      expect.any(Object),
+      expect.any(Function)
+    );
+  });
+
+  it('renders Office thumbnails from the cached converted PDF after conversion cleanup', async () => {
+    mockedMkdtemp.mockImplementation(async (prefix) =>
+      String(prefix).includes('codeman-document-preview-cache')
+        ? '/tmp/codeman-document-preview-cache/work-test'
+        : '/tmp/codeman-thumb-pdf-test'
+    );
+    mockedExecFile.mockImplementation((_cmd, _args, _options, callback) => {
+      callback(null, { stdout: '', stderr: '' });
+      return {} as never;
+    });
+
+    const result = await generateFirstPageThumbnail('/tmp/deck.pptx', 'pptx');
+
+    expect(result).toEqual({
+      content: Buffer.from('large thumbnail'),
+      contentType: 'image/png',
+    });
+    const pdftoppmCall = mockedExecFile.mock.calls.find(([cmd]) => cmd === 'pdftoppm');
+    expect(pdftoppmCall?.[1]).toEqual(
+      expect.arrayContaining([expect.stringContaining('codeman-document-preview-cache')])
+    );
+  });
+});

test/image-watcher.test.ts

@@ -145,9 +145,9 @@ describe('ImageWatcher', () => {
   // ========== Image Detection ==========
 
   describe('image detection', () => {
-    it('should emit image:detected (popup) for .png files', () => {
+    it('should emit attachment:detected for .png files', () => {
       const handler = vi.fn();
-      watcher.on('image:detected', handler);
+      watcher.on('attachment:detected', handler);
 
       watcher.watchSession('session-1', '/home/user/project');
       const chokidarWatcher = mockWatchers.get('/home/user/project')!;
@@ -161,11 +161,14 @@ describe('ImageWatcher', () => {
       expect(event.fileName).toBe('screenshot.png');
       expect(event.filePath).toBe('/home/user/project/screenshot.png');
       expect(event.relativePath).toBe('screenshot.png');
+      expect(event.extension).toBe('png');
+      expect(event.attachmentType).toBe('image');
+      expect(event.size).toBe(2048);
     });
 
-    it('should not emit attachment:detected for .png (stays on the popup path)', () => {
+    it('should not emit legacy image:detected for .png attachment cards', () => {
       const handler = vi.fn();
-      watcher.on('attachment:detected', handler);
+      watcher.on('image:detected', handler);
 
       watcher.watchSession('session-1', '/home/user/project');
       mockWatchers.get('/home/user/project')!.emit('add', '/home/user/project/screenshot.png');

test/routes/file-routes-preview-thumbnail.test.ts

@@ -0,0 +1,156 @@
+/**
+ * @fileoverview Route coverage for the document preview/thumbnail endpoints
+ * added in COD-38 (PR #120): the by-attachmentId routes
+ * (/attachments/:id/preview|thumbnail) and the workspace-path routes
+ * (/file-preview|/file-thumbnail). Converters are mocked, so no real
+ * pdftoppm/LibreOffice is needed. Uses app.inject() — no real ports.
+ */
+
+import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest';
+import { createRouteTestHarness, type RouteTestHarness } from './_route-test-utils.js';
+import { registerFileRoutes } from '../../src/web/routes/file-routes.js';
+
+vi.mock('node:fs/promises', () => ({
+  default: {
+    readFile: vi.fn(async () => Buffer.from('%PDF-1.4 fake pdf bytes')),
+    stat: vi.fn(async () => ({ size: 100, isFile: () => true, mtimeMs: 1 })),
+    readdir: vi.fn(async () => []),
+    mkdir: vi.fn(async () => undefined),
+    mkdtemp: vi.fn(async () => '/tmp/codeman-preview-test'),
+    rename: vi.fn(async () => undefined),
+    rm: vi.fn(async () => undefined),
+  },
+}));
+
+vi.mock('node:fs', async (importOriginal) => {
+  const actual = await importOriginal<typeof import('node:fs')>();
+  return { ...actual, realpathSync: vi.fn((p: string) => p) };
+});
+
+// Mock the converters so the routes don't shell out to real binaries.
+vi.mock('../../src/document-thumbnailer.js', () => ({
+  generateFirstPageThumbnail: vi.fn(async () => ({ content: Buffer.from('\x89PNG fake'), contentType: 'image/png' })),
+}));
+vi.mock('../../src/document-preview-cache.js', () => ({
+  getOfficePreviewPdfPath: vi.fn(async () => '/tmp/codeman-document-preview-cache/out.pdf'),
+  getPreviewPdfDownloadName: vi.fn((name: string) => `${name.replace(/\.[^.]+$/, '')}.pdf`),
+}));
+
+import { generateFirstPageThumbnail } from '../../src/document-thumbnailer.js';
+import { getOfficePreviewPdfPath } from '../../src/document-preview-cache.js';
+import { attachmentRegistry, type AttachmentRecord } from '../../src/attachment-registry.js';
+
+const SID = 'test-session-1';
+const WORKDIR = '/tmp/test-workdir';
+
+function makeRecord(over: Partial<AttachmentRecord>): AttachmentRecord {
+  return {
+    attachmentId: 'att_x',
+    sessionId: SID,
+    filePath: `${WORKDIR}/file`,
+    fileName: 'file',
+    extension: 'pdf',
+    attachmentType: 'document',
+    size: 100,
+    mtimeMs: 1,
+    timestamp: 1,
+    source: 'detected',
+    ...over,
+  };
+}
+
+describe('file-routes preview/thumbnail (COD-38)', () => {
+  let harness: RouteTestHarness;
+
+  beforeEach(async () => {
+    harness = await createRouteTestHarness(registerFileRoutes, { sessionId: SID });
+    vi.clearAllMocks();
+    attachmentRegistry.clearSession(SID);
+  });
+
+  afterEach(async () => {
+    await harness.app.close();
+    attachmentRegistry.clearSession(SID);
+  });
+
+  // ---- workspace-path routes ----
+
+  it('file-preview converts a workspace DOCX to an inline PDF', async () => {
+    const res = await harness.app.inject({ method: 'GET', url: `/api/sessions/${SID}/file-preview?path=deck.docx` });
+    expect(res.statusCode).toBe(200);
+    expect(res.headers['content-type']).toContain('application/pdf');
+    expect(res.headers['content-disposition']).toContain('inline');
+    expect(getOfficePreviewPdfPath).toHaveBeenCalled();
+  });
+
+  it('file-preview redirects a non-Office workspace file (PDF) to the raw route', async () => {
+    const res = await harness.app.inject({ method: 'GET', url: `/api/sessions/${SID}/file-preview?path=report.pdf` });
+    expect(res.statusCode).toBeGreaterThanOrEqual(300);
+    expect(res.statusCode).toBeLessThan(400);
+    expect(res.headers.location).toContain('/file-raw?path=report.pdf');
+    expect(getOfficePreviewPdfPath).not.toHaveBeenCalled();
+  });
+
+  it('file-preview 400s for a missing path parameter', async () => {
+    const res = await harness.app.inject({ method: 'GET', url: `/api/sessions/${SID}/file-preview` });
+    expect(res.statusCode).toBe(400);
+  });
+
+  it('file-thumbnail returns a PNG for a supported workspace file', async () => {
+    const res = await harness.app.inject({ method: 'GET', url: `/api/sessions/${SID}/file-thumbnail?path=deck.pdf` });
+    expect(res.statusCode).toBe(200);
+    expect(res.headers['content-type']).toContain('image/png');
+    expect(res.headers['x-content-type-options']).toBe('nosniff');
+    expect(generateFirstPageThumbnail).toHaveBeenCalled();
+  });
+
+  it('file-thumbnail 400s for an unsupported extension', async () => {
+    const res = await harness.app.inject({ method: 'GET', url: `/api/sessions/${SID}/file-thumbnail?path=notes.exe` });
+    expect(res.statusCode).toBe(400);
+    expect(generateFirstPageThumbnail).not.toHaveBeenCalled();
+  });
+
+  // ---- by-attachmentId routes ----
+
+  it('by-id preview converts a registered DOCX attachment', async () => {
+    attachmentRegistry.register(
+      makeRecord({
+        attachmentId: 'att_docx',
+        filePath: `${WORKDIR}/deck.docx`,
+        fileName: 'deck.docx',
+        extension: 'docx',
+      })
+    );
+    const res = await harness.app.inject({
+      method: 'GET',
+      url: `/api/sessions/${SID}/attachments/att_docx/preview`,
+    });
+    expect(res.statusCode).toBe(200);
+    expect(res.headers['content-type']).toContain('application/pdf');
+  });
+
+  it('by-id preview redirects a non-Office attachment (PNG) to its raw route', async () => {
+    attachmentRegistry.register(
+      makeRecord({ attachmentId: 'att_png', filePath: `${WORKDIR}/shot.png`, fileName: 'shot.png', extension: 'png' })
+    );
+    const res = await harness.app.inject({
+      method: 'GET',
+      url: `/api/sessions/${SID}/attachments/att_png/preview`,
+    });
+    expect(res.statusCode).toBeGreaterThanOrEqual(300);
+    expect(res.statusCode).toBeLessThan(400);
+    expect(res.headers.location).toContain('/attachments/att_png/raw');
+  });
+
+  it('by-id thumbnail returns a PNG for a registered attachment', async () => {
+    attachmentRegistry.register(
+      makeRecord({ attachmentId: 'att_pdf', filePath: `${WORKDIR}/deck.pdf`, fileName: 'deck.pdf', extension: 'pdf' })
+    );
+    const res = await harness.app.inject({
+      method: 'GET',
+      url: `/api/sessions/${SID}/attachments/att_pdf/thumbnail`,
+    });
+    expect(res.statusCode).toBe(200);
+    expect(res.headers['content-type']).toContain('image/png');
+  });
+});