feat(mobile): add filesystem path picker

src/types/common.ts

@@ -9,6 +9,7 @@
  * - CleanupRegistration / CleanupResourceType — entries for the centralized CleanupManager
  * - NiceConfig / DEFAULT_NICE_CONFIG — process priority settings for `nice`/`ionice`
  * - ProcessStats — memory/CPU/child-count snapshot for resource monitoring
+ * - FilesystemBrowseData — bounded path-picker directory listing returned to the web UI
  */
 
 /**
@@ -68,6 +69,31 @@ export interface ProcessStats {
   updatedAt: number;
 }
 
+/** A selectable entry returned by the filesystem path-picker API. */
+export interface FilesystemBrowseEntry {
+  name: string;
+  path: string;
+  type: 'file' | 'directory';
+  size?: number;
+  symlink?: boolean;
+}
+
+/** A named root the path picker may browse without escaping its allowlist. */
+export interface FilesystemBrowseRoot {
+  label: string;
+  path: string;
+}
+
+/** Response payload for `GET /api/filesystem/browse`. */
+export interface FilesystemBrowseData {
+  path: string;
+  parent: string | null;
+  root: string;
+  roots: FilesystemBrowseRoot[];
+  entries: FilesystemBrowseEntry[];
+  truncated: boolean;
+}
+
 export type CleanupResourceType = 'timer' | 'interval' | 'watcher' | 'listener' | 'stream';
 
 /**

src/web/public/index.html

@@ -1962,8 +1962,11 @@
             </div>
             <div class="form-row">
               <label>Folder Path</label>
-              <input type="text" id="linkCasePath" placeholder="/home/user/projects/my-project" autocomplete="off" autocapitalize="off" autocorrect="off" spellcheck="false">
-              <span class="form-hint">Absolute path to an existing project folder, e.g. /home/you/my-project</span>
+              <div class="path-input-group">
+                <input type="text" id="linkCasePath" placeholder="/mnt/d/AI/my-project" autocomplete="off" autocapitalize="off" autocorrect="off" spellcheck="false">
+                <button type="button" class="btn path-input-browse" onclick="app.openLinkCasePathPicker()">Browse&hellip;</button>
+              </div>
+              <span class="form-hint">Choose an existing folder from this computer or enter its absolute path</span>
             </div>
           </div>
           <!-- Remote Tab -->

src/web/public/keyboard-accessory.js

@@ -1,7 +1,7 @@
 /**
  * @fileoverview Mobile keyboard accessory bar and modal focus trap.
  *
- * Defines two exports:
+ * Defines three exports:
  *
  * - KeyboardAccessoryBar (singleton object) — Quick action buttons shown above the virtual
  *   keyboard on mobile: arrow up/down, /init, /clear, /compact, paste, Esc, and dismiss.
@@ -10,12 +10,15 @@
  *   Destructive actions (/clear, /compact) require double-tap confirmation (2s amber state).
  *   Commands are sent as text + Enter separately for Ink compatibility.
  *   Only initializes on touch devices (MobileDetection.isTouchDevice guard).
+ * - PathPicker (singleton object) — Lazy server-side file/folder browser shared
+ *   by Link Existing and the extended mobile keyboard bar.
  *
  * - FocusTrap (class) — Traps Tab/Shift+Tab keyboard focus within a modal element.
  *   Saves and restores previously focused element on deactivate. Used by Ralph wizard
  *   and other modal dialogs.
  *
  * @globals {object} KeyboardAccessoryBar
+ * @globals {object} PathPicker
  * @globals {class} FocusTrap
  *
  * @dependency mobile-handlers.js (MobileDetection.isTouchDevice)
@@ -26,6 +29,227 @@
 // Codeman — Keyboard accessory bar and focus trap for modals
 // Loaded after mobile-handlers.js, before app.js
 
+// ═══════════════════════════════════════════════════════════════
+// Shared Filesystem Path Picker
+// ═══════════════════════════════════════════════════════════════
+
+const PathPicker = {
+  overlay: null,
+  _options: null,
+  _selectedPath: '',
+  _previousFocus: null,
+  _keydownHandler: null,
+  _loadSequence: 0,
+
+  /**
+   * Open the lazy filesystem browser.
+   * @param {{sessionId?: string, initialPath?: string, directoriesOnly?: boolean,
+   *   title?: string, onSelect: (path: string) => void}} options
+   */
+  open(options) {
+    this.close(false);
+    this._options = options;
+    this._selectedPath = '';
+    this._previousFocus = document.activeElement;
+    this._previousFocus?.blur?.();
+
+    const overlay = document.createElement('div');
+    overlay.className = 'path-picker-overlay';
+    overlay.setAttribute('role', 'dialog');
+    overlay.setAttribute('aria-modal', 'true');
+    overlay.setAttribute('aria-label', options.title || 'Select a path');
+    overlay.innerHTML = `
+      <div class="path-picker-dialog">
+        <div class="path-picker-header">
+          <strong class="path-picker-title"></strong>
+          <button type="button" class="path-picker-close" aria-label="Close">&times;</button>
+        </div>
+        <div class="path-picker-roots-row">
+          <label for="pathPickerRoot">Location</label>
+          <select id="pathPickerRoot" class="path-picker-roots"></select>
+        </div>
+        <div class="path-picker-nav">
+          <button type="button" class="path-picker-up" title="Parent folder" aria-label="Parent folder">&#x2191;</button>
+          <div class="path-picker-current" title="Current folder"></div>
+          <button type="button" class="path-picker-refresh" title="Refresh" aria-label="Refresh">&#x21BB;</button>
+        </div>
+        <div class="path-picker-status" aria-live="polite">Loading...</div>
+        <div class="path-picker-list" role="listbox"></div>
+        <div class="path-picker-selection">
+          <span class="path-picker-selection-label">Selected</span>
+          <span class="path-picker-selection-value">None</span>
+        </div>
+        <div class="path-picker-actions">
+          <button type="button" class="path-picker-current-select">Select Current Folder</button>
+          <span class="path-picker-action-spacer"></span>
+          <button type="button" class="path-picker-cancel">Cancel</button>
+          <button type="button" class="path-picker-confirm" disabled>Select</button>
+        </div>
+      </div>`;
+
+    this.overlay = overlay;
+    overlay.querySelector('.path-picker-title').textContent = options.title || 'Select a Path';
+    overlay.querySelector('.path-picker-close').addEventListener('click', () => this.close(true));
+    overlay.querySelector('.path-picker-cancel').addEventListener('click', () => this.close(true));
+    overlay.querySelector('.path-picker-confirm').addEventListener('click', () => this.confirm());
+    overlay.querySelector('.path-picker-current-select').addEventListener('click', () => {
+      const current = overlay.querySelector('.path-picker-current').textContent;
+      if (current) this.select(current);
+    });
+    overlay.querySelector('.path-picker-refresh').addEventListener('click', () => this.load());
+    overlay.querySelector('.path-picker-up').addEventListener('click', () => {
+      const parent = overlay.querySelector('.path-picker-up').dataset.parent;
+      if (parent) this.load(parent);
+    });
+    overlay.querySelector('.path-picker-roots').addEventListener('change', (event) => this.load(event.target.value));
+    overlay.addEventListener('click', (event) => {
+      if (event.target === overlay) this.close(true);
+    });
+    this._keydownHandler = (event) => {
+      if (event.key === 'Escape') {
+        event.preventDefault();
+        this.close(true);
+      }
+    };
+    document.addEventListener('keydown', this._keydownHandler);
+    document.body.appendChild(overlay);
+    this.load(options.initialPath || '');
+  },
+
+  async load(path) {
+    if (!this.overlay || !this._options) return;
+    const loadSequence = ++this._loadSequence;
+    const list = this.overlay.querySelector('.path-picker-list');
+    const status = this.overlay.querySelector('.path-picker-status');
+    list.replaceChildren();
+    status.textContent = 'Loading...';
+
+    const params = new URLSearchParams();
+    if (path) params.set('path', path);
+    if (this._options.sessionId) params.set('sessionId', this._options.sessionId);
+    try {
+      const response = await fetch(`/api/filesystem/browse?${params.toString()}`);
+      const result = await response.json();
+      if (!response.ok || !result.success) throw new Error(result.error || 'Failed to browse this folder');
+      if (!this.overlay || loadSequence !== this._loadSequence) return;
+      this.render(result.data);
+    } catch (error) {
+      if (!this.overlay || loadSequence !== this._loadSequence) return;
+      if (path) {
+        this.load('');
+        return;
+      }
+      status.textContent = error.message || 'Failed to browse this folder';
+      status.classList.add('error');
+    }
+  },
+
+  render(data) {
+    const rootSelect = this.overlay.querySelector('.path-picker-roots');
+    rootSelect.replaceChildren();
+    for (const root of data.roots) {
+      const option = document.createElement('option');
+      option.value = root.path;
+      option.textContent = `${root.label} — ${root.path}`;
+      option.selected = data.path === root.path || data.root === root.path;
+      rootSelect.appendChild(option);
+    }
+
+    this.overlay.querySelector('.path-picker-current').textContent = data.path;
+    const up = this.overlay.querySelector('.path-picker-up');
+    up.dataset.parent = data.parent || '';
+    up.disabled = !data.parent;
+    const status = this.overlay.querySelector('.path-picker-status');
+    status.classList.remove('error');
+    status.textContent = data.entries.length === 0
+      ? 'This folder is empty'
+      : `${data.entries.length} item${data.entries.length === 1 ? '' : 's'}${data.truncated ? ' (first 500)' : ''}`;
+
+    const list = this.overlay.querySelector('.path-picker-list');
+    list.replaceChildren();
+    for (const entry of data.entries) {
+      const row = document.createElement('div');
+      row.className = 'path-picker-item';
+      if (entry.type === 'file' && this._options.directoriesOnly) row.classList.add('not-selectable');
+      row.dataset.path = entry.path;
+      row.dataset.type = entry.type;
+      row.setAttribute('role', 'option');
+
+      const open = document.createElement('button');
+      open.type = 'button';
+      open.className = 'path-picker-item-main';
+      const icon = document.createElement('span');
+      icon.className = 'path-picker-item-icon';
+      icon.textContent = entry.type === 'directory' ? '\uD83D\uDCC1' : '\uD83D\uDCC4';
+      const name = document.createElement('span');
+      name.className = 'path-picker-item-name';
+      name.textContent = entry.name;
+      open.append(icon, name);
+      if (entry.symlink) {
+        const link = document.createElement('span');
+        link.className = 'path-picker-item-link';
+        link.textContent = '\u2197';
+        open.appendChild(link);
+      }
+      if (entry.type === 'directory') {
+        const chevron = document.createElement('span');
+        chevron.className = 'path-picker-item-chevron';
+        chevron.textContent = '\u203A';
+        open.appendChild(chevron);
+        open.addEventListener('click', () => this.load(entry.path));
+      } else if (!this._options.directoriesOnly) {
+        open.addEventListener('click', () => this.select(entry.path));
+      } else {
+        open.disabled = true;
+      }
+      row.appendChild(open);
+
+      if (entry.type === 'directory' || !this._options.directoriesOnly) {
+        const choose = document.createElement('button');
+        choose.type = 'button';
+        choose.className = 'path-picker-item-select';
+        choose.textContent = 'Choose';
+        choose.addEventListener('click', () => this.select(entry.path));
+        row.appendChild(choose);
+      }
+      list.appendChild(row);
+    }
+  },
+
+  select(path) {
+    if (!this.overlay) return;
+    this._selectedPath = path;
+    this.overlay.querySelector('.path-picker-selection-value').textContent = path;
+    this.overlay.querySelector('.path-picker-confirm').disabled = false;
+    this.overlay.querySelectorAll('.path-picker-item').forEach((row) => {
+      const selected = row.dataset.path === path;
+      row.classList.toggle('selected', selected);
+      row.setAttribute('aria-selected', selected ? 'true' : 'false');
+    });
+  },
+
+  confirm() {
+    if (!this._selectedPath || !this._options) return;
+    const selectedPath = this._selectedPath;
+    const onSelect = this._options.onSelect;
+    this.close(false);
+    onSelect(selectedPath);
+  },
+
+  close(restoreFocus = true) {
+    if (this._keydownHandler) document.removeEventListener('keydown', this._keydownHandler);
+    this._keydownHandler = null;
+    this._loadSequence += 1;
+    this.overlay?.remove();
+    this.overlay = null;
+    const previousFocus = this._previousFocus;
+    this._previousFocus = null;
+    this._options = null;
+    this._selectedPath = '';
+    if (restoreFocus) previousFocus?.focus?.();
+  },
+};
+
 // ═══════════════════════════════════════════════════════════════
 // Mobile Keyboard Accessory Bar
 // ═══════════════════════════════════════════════════════════════
@@ -92,6 +316,8 @@ const KeyboardAccessoryBar = {
           <rect x="8" y="2" width="8" height="4" rx="1" ry="1"/>
         </svg>
       </button>
+      <button class="accessory-btn" data-action="pick-path" title="Insert a file or folder path">&#x1F4C1; Path</button>
+      <button class="accessory-btn" data-action="clear-input" title="Clear the current unsent input">&#x232B; All</button>
       <button class="accessory-btn" data-action="tab" title="Tab">Tab</button>
       <button class="accessory-btn" data-action="shift-tab" title="Shift+Tab">⇧Tab</button>
       <button class="accessory-btn" data-action="effort-max" title="/effort max">Max</button>
@@ -128,7 +354,7 @@ const KeyboardAccessoryBar = {
       this.handleAction(action, btn);
 
       // Refocus terminal so keyboard stays open (tap blurs terminal → keyboard dismisses → toolbar shifts)
-      const refocusActions = new Set(['scroll-up', 'scroll-down', 'arrow-left', 'arrow-right', 'tab', 'shift-tab', 'ctrl-o', 'opt-enter', 'esc', 'effort-max']);
+      const refocusActions = new Set(['scroll-up', 'scroll-down', 'arrow-left', 'arrow-right', 'tab', 'shift-tab', 'ctrl-o', 'opt-enter', 'esc', 'effort-max', 'clear-input']);
       if (refocusActions.has(action) ||
           ((action === 'clear' || action === 'compact') && this._confirmAction)) {
         if (typeof app !== 'undefined' && app.terminal) {
@@ -207,6 +433,12 @@ const KeyboardAccessoryBar = {
       case 'paste':
         this.pasteFromClipboard();
         break;
+      case 'pick-path':
+        this.pickPath();
+        break;
+      case 'clear-input':
+        app.clearTerminalInput?.();
+        break;
       case 'dismiss':
         // Blur active element to dismiss keyboard
         document.activeElement?.blur();
@@ -265,6 +497,22 @@ const KeyboardAccessoryBar = {
     }).catch(() => {});
   },
 
+  /** Browse the active session's workspace and insert a selected path without Enter. */
+  pickPath() {
+    if (!app.activeSessionId) return;
+    const session = app.sessions?.get(app.activeSessionId);
+    PathPicker.open({
+      title: 'Insert File or Folder Path',
+      sessionId: app.activeSessionId,
+      initialPath: session?.workingDir || '',
+      directoriesOnly: false,
+      onSelect: (path) => {
+        app.insertTerminalText?.(path);
+        setTimeout(() => app.terminal?.focus(), 100);
+      },
+    });
+  },
+
   /** Show a paste overlay for iOS compatibility.
    *  Handles three input paths from one dialog:
    *   - Text: long-press the textarea → Paste → Send (unchanged).

src/web/public/session-ui.js

@@ -1863,6 +1863,25 @@ Object.assign(CodemanApp.prototype, {
     }
   },
 
+  openLinkCasePathPicker() {
+    const pathInput = document.getElementById('linkCasePath');
+    PathPicker.open({
+      title: 'Select Existing Project Folder',
+      initialPath: pathInput.value.trim(),
+      directoriesOnly: true,
+      onSelect: (path) => {
+        pathInput.value = path;
+        const nameInput = document.getElementById('linkCaseName');
+        if (!nameInput.value.trim()) {
+          const folderName = path.split('/').filter(Boolean).pop() || '';
+          if (/^[\p{L}\p{N}_-]+$/u.test(folderName)) nameInput.value = folderName;
+        }
+        pathInput.focus();
+        pathInput.setSelectionRange(path.length, path.length);
+      },
+    });
+  },
+
   async linkRemoteCase() {
     const name = document.getElementById('remoteCaseName').value.trim();
     const remotePath = document.getElementById('remoteCasePath').value.trim();

src/web/public/styles.css

@@ -10845,6 +10845,283 @@ body.touch-device.cjk-input-visible .main {
   font-weight: 600;
 }
 
+/* Shared lazy filesystem path picker (case linking + mobile input). */
+.path-input-group {
+  display: flex;
+  gap: 8px;
+  width: 100%;
+}
+
+.path-input-group input {
+  flex: 1 1 auto;
+  min-width: 0;
+}
+
+.path-input-browse {
+  flex: 0 0 auto;
+  min-height: 38px;
+}
+
+.path-picker-overlay {
+  position: fixed;
+  inset: 0;
+  z-index: 10020;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  padding: 16px;
+  background: rgba(0, 0, 0, 0.72);
+  backdrop-filter: blur(4px);
+  -webkit-backdrop-filter: blur(4px);
+}
+
+.path-picker-dialog {
+  display: flex;
+  flex-direction: column;
+  width: min(680px, 100%);
+  height: min(720px, calc(100dvh - 32px));
+  overflow: hidden;
+  color: var(--text);
+  background: var(--bg-card);
+  border: 1px solid var(--border);
+  border-radius: 14px;
+  box-shadow: 0 24px 64px rgba(0, 0, 0, 0.5);
+}
+
+.path-picker-header,
+.path-picker-nav,
+.path-picker-roots-row,
+.path-picker-selection,
+.path-picker-actions {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+}
+
+.path-picker-header {
+  justify-content: space-between;
+  padding: 14px 16px;
+  border-bottom: 1px solid var(--border);
+}
+
+.path-picker-title {
+  font-size: 0.95rem;
+}
+
+.path-picker-close {
+  width: 36px;
+  height: 36px;
+  color: var(--text-muted);
+  font-size: 1.5rem;
+  background: transparent;
+  border: 0;
+  border-radius: 8px;
+  cursor: pointer;
+}
+
+.path-picker-roots-row {
+  padding: 10px 12px 0;
+  color: var(--text-muted);
+  font-size: 0.75rem;
+}
+
+.path-picker-roots {
+  flex: 1;
+  min-width: 0;
+  padding: 8px 10px;
+  color: var(--text);
+  background: var(--bg-input);
+  border: 1px solid var(--border);
+  border-radius: 8px;
+}
+
+.path-picker-nav {
+  padding: 10px 12px;
+}
+
+.path-picker-up,
+.path-picker-refresh {
+  flex: 0 0 38px;
+  height: 38px;
+  color: var(--text);
+  background: var(--bg-input);
+  border: 1px solid var(--border);
+  border-radius: 8px;
+  cursor: pointer;
+}
+
+.path-picker-up:disabled {
+  opacity: 0.35;
+  cursor: default;
+}
+
+.path-picker-current {
+  flex: 1;
+  min-width: 0;
+  padding: 9px 11px;
+  overflow-x: auto;
+  color: var(--accent);
+  font-family: var(--font-mono, monospace);
+  font-size: 0.75rem;
+  white-space: nowrap;
+  background: var(--bg-input);
+  border: 1px solid var(--border);
+  border-radius: 8px;
+}
+
+.path-picker-status {
+  padding: 0 14px 8px;
+  color: var(--text-dim);
+  font-size: 0.7rem;
+}
+
+.path-picker-status.error {
+  color: var(--danger, #ef4444);
+}
+
+.path-picker-list {
+  flex: 1;
+  min-height: 140px;
+  overflow-y: auto;
+  padding: 0 10px 10px;
+}
+
+.path-picker-item {
+  display: flex;
+  align-items: stretch;
+  margin: 2px 0;
+  border: 1px solid transparent;
+  border-radius: 9px;
+}
+
+.path-picker-item:hover,
+.path-picker-item.selected {
+  background: var(--bg-hover);
+  border-color: var(--border);
+}
+
+.path-picker-item.selected {
+  border-color: var(--accent);
+}
+
+.path-picker-item.not-selectable {
+  opacity: 0.62;
+}
+
+.path-picker-item-main {
+  display: flex;
+  flex: 1;
+  align-items: center;
+  min-width: 0;
+  padding: 10px 8px;
+  color: var(--text);
+  text-align: left;
+  background: transparent;
+  border: 0;
+  cursor: pointer;
+}
+
+.path-picker-item-name {
+  flex: 1;
+  min-width: 0;
+  overflow: hidden;
+  font-size: 0.8rem;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+.path-picker-item-icon {
+  margin-right: 8px;
+}
+
+.path-picker-item-link,
+.path-picker-item-chevron {
+  margin-left: 8px;
+  color: var(--text-dim);
+}
+
+.path-picker-item-select {
+  align-self: center;
+  margin-right: 6px;
+  padding: 6px 9px;
+  color: var(--accent);
+  background: transparent;
+  border: 1px solid var(--border);
+  border-radius: 7px;
+  cursor: pointer;
+}
+
+.path-picker-selection {
+  padding: 9px 14px;
+  color: var(--text-muted);
+  font-size: 0.72rem;
+  border-top: 1px solid var(--border);
+}
+
+.path-picker-selection-value {
+  min-width: 0;
+  overflow: hidden;
+  color: var(--text);
+  font-family: var(--font-mono, monospace);
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+.path-picker-actions {
+  padding: 10px 12px 12px;
+}
+
+.path-picker-actions button {
+  min-height: 40px;
+  padding: 8px 13px;
+  color: var(--text);
+  background: var(--bg-input);
+  border: 1px solid var(--border);
+  border-radius: 8px;
+  cursor: pointer;
+}
+
+.path-picker-action-spacer {
+  flex: 1;
+}
+
+.path-picker-actions .path-picker-confirm {
+  color: #fff;
+  background: var(--accent);
+  border-color: var(--accent);
+  font-weight: 600;
+}
+
+.path-picker-actions .path-picker-confirm:disabled {
+  opacity: 0.4;
+  cursor: default;
+}
+
+@media (max-width: 600px) {
+  .path-picker-overlay {
+    align-items: flex-end;
+    padding: 0;
+  }
+
+  .path-picker-dialog {
+    width: 100%;
+    height: min(82dvh, 720px);
+    border-right: 0;
+    border-bottom: 0;
+    border-left: 0;
+    border-radius: 16px 16px 0 0;
+    padding-bottom: env(safe-area-inset-bottom, 0px);
+  }
+
+  .path-picker-actions {
+    flex-wrap: wrap;
+  }
+
+  .path-picker-current-select {
+    flex: 1 1 100%;
+  }
+}
+
 /* ═══════════════════════════════════════════════════════════════
    Orchestrator Panel
    ═══════════════════════════════════════════════════════════════ */

src/web/public/terminal-ui.js

@@ -2418,6 +2418,50 @@ Object.assign(CodemanApp.prototype, {
     this.terminal.clear();
   },
 
+  /** Insert editable text at the active prompt without pressing Enter. */
+  insertTerminalText(text) {
+    if (!this.activeSessionId || !text) return;
+    if (this._localEchoEnabled && this._localEchoOverlay) {
+      this._localEchoOverlay.appendText(text);
+    } else {
+      this.sendInput(text).catch(() => {});
+    }
+    this.terminal?.focus();
+  },
+
+  /**
+   * Clear only the current editable prompt. This is intentionally distinct
+   * from Ctrl+L (clear display) and the agent's destructive `/clear` command.
+   */
+  clearTerminalInput() {
+    if (!this.activeSessionId) return;
+
+    if (typeof CjkInput !== 'undefined') CjkInput.clear();
+    if (this._inputFlushTimeout) {
+      clearTimeout(this._inputFlushTimeout);
+      this._inputFlushTimeout = null;
+    }
+    this._pendingInput = '';
+
+    if (this._localEchoEnabled && this._localEchoOverlay) {
+      const flushed = this._localEchoOverlay.getFlushed?.() || { count: 0, text: '' };
+      this._localEchoOverlay.clear();
+      this._localEchoOverlay.suppressBufferDetection();
+      this._flushedOffsets?.delete(this.activeSessionId);
+      this._flushedTexts?.delete(this.activeSessionId);
+      if (flushed.count > 0) {
+        this.sendInput('\x7f'.repeat(flushed.count)).catch(() => {});
+      }
+    } else {
+      // In non-local-echo mode the TUI already owns the editable buffer. Ctrl+U
+      // is the conventional kill-line key supported by shells and agent TUIs.
+      this.sendInput('\x15').catch(() => {});
+    }
+
+    this.showToast?.('Input cleared', 'success');
+    this.terminal?.focus();
+  },
+
   /**
    * Restore terminal size to match web UI dimensions.
    * Use this after mobile screen attachment has squeezed the terminal.

src/web/routes/file-routes.ts

@@ -4,9 +4,11 @@
  */
 
 import { FastifyInstance, type FastifyReply } from 'fastify';
-import { basename as pathBasename, join } from 'node:path';
+import { basename as pathBasename, isAbsolute, join, relative, resolve, sep } from 'node:path';
 import { createReadStream, realpathSync, type ReadStream } from 'node:fs';
 import fs from 'node:fs/promises';
+import { homedir } from 'node:os';
+import type { ApiResponse, FilesystemBrowseData, FilesystemBrowseEntry, FilesystemBrowseRoot } from '../../types.js';
 import { ApiErrorCode, createErrorResponse, getErrorMessage } from '../../types.js';
 import { fileStreamManager } from '../../file-stream-manager.js';
 import {
@@ -22,12 +24,20 @@ import { generateFirstPageThumbnail } from '../../document-thumbnailer.js';
 import { getOfficePreviewPdfPath, getPreviewPdfDownloadName } from '../../document-preview-cache.js';
 import { sanitizeAttachmentHistoryItem } from '../../session-attachment-history.js';
 import { isBlockedAttachmentPath, loadAttachmentGuardConfig } from '../../config/attachment-guard.js';
-import { canAccessOwned, findSessionOrFail, getAuthUser, validateSessionFilePath } from '../route-helpers.js';
+import {
+  CASES_DIR,
+  canAccessOwned,
+  findSessionOrFail,
+  getAuthUser,
+  parseBody,
+  validateSessionFilePath,
+} from '../route-helpers.js';
 import type { FastifyRequest } from 'fastify';
 import type { SessionAttachmentHistoryItem, SessionState } from '../../types/session.js';
 import { isSensitivePath } from '../sensitive-path.js';
 import { SseEvent } from '../sse-events.js';
 import type { ConfigPort, EventPort, SessionPort } from '../ports/index.js';
+import { FilesystemBrowseQuerySchema } from '../schemas.js';
 
 const MIME_TYPES: Record<string, string> = {
   png: 'image/png',
@@ -260,6 +270,75 @@ type AttachmentHistoryRouteItem = Omit<SessionAttachmentHistoryItem, 'externalPa
   attachmentId?: string;
 };
 
+const FILESYSTEM_PICKER_ENTRY_LIMIT = 500;
+
+function isPathWithinRoot(root: string, candidate: string): boolean {
+  const rel = relative(root, candidate);
+  return rel === '' || (!isAbsolute(rel) && rel !== '..' && !rel.startsWith(`..${sep}`));
+}
+
+function isBlockedPickerPath(path: string, blockedTrees: readonly string[], directory = false): boolean {
+  if (isBlockedAttachmentPath(path, blockedTrees)) return true;
+  // The shared sensitive-path matcher describes file locations such as
+  // ~/.ssh/<key>. Probe a child path as well so the directory itself cannot be
+  // opened and used to enumerate those filenames.
+  return directory && isBlockedAttachmentPath(join(path, '__codeman_path_picker_probe__'), blockedTrees);
+}
+
+function configuredFilesystemPickerRoots(): Array<{ label: string; path: string }> {
+  const candidates: Array<{ label: string; path: string }> = [
+    { label: 'Home', path: homedir() },
+    { label: 'Codeman Cases', path: CASES_DIR },
+    { label: 'WSL D:', path: '/mnt/d' },
+  ];
+  const extraRoots = process.env.CODEMAN_FILE_PICKER_ROOTS;
+  if (extraRoots) {
+    for (const [index, path] of extraRoots
+      .split(',')
+      .map((value) => value.trim())
+      .filter(Boolean)
+      .entries()) {
+      candidates.push({ label: `Configured ${index + 1}`, path });
+    }
+  }
+  return candidates;
+}
+
+async function resolveFilesystemPickerRoots(
+  ctx: SessionPort & ConfigPort,
+  sessionId?: string
+): Promise<FilesystemBrowseRoot[]> {
+  const candidates = configuredFilesystemPickerRoots();
+  if (sessionId) {
+    const session = ctx.sessions.get(sessionId) ?? ctx.store.getSession(sessionId);
+    if (!session) {
+      throw Object.assign(new Error(`Session ${sessionId} not found`), {
+        statusCode: 404,
+        body: createErrorResponse(ApiErrorCode.NOT_FOUND, `Session ${sessionId} not found`),
+      });
+    }
+    candidates.unshift({ label: 'Current Folder', path: session.workingDir });
+  }
+
+  const guard = await loadAttachmentGuardConfig();
+  const roots: FilesystemBrowseRoot[] = [];
+  const seen = new Set<string>();
+  for (const candidate of candidates) {
+    if (!isAbsolute(candidate.path)) continue;
+    try {
+      const resolved = realpathSync(candidate.path);
+      if (seen.has(resolved) || isBlockedPickerPath(resolved, guard.blockedTrees, true)) continue;
+      const stat = await fs.stat(resolved);
+      if (!stat.isDirectory()) continue;
+      seen.add(resolved);
+      roots.push({ label: candidate.label, path: resolved });
+    } catch {
+      // Optional roots (for example /mnt/d on non-WSL hosts) are omitted.
+    }
+  }
+  return roots;
+}
+
 function appendDownloadFlag(url: string): string {
   return `${url}${url.includes('?') ? '&' : '?'}download=true`;
 }
@@ -375,6 +454,141 @@ async function buildExternalAttachmentRouteItem(
 }
 
 export function registerFileRoutes(app: FastifyInstance, ctx: SessionPort & EventPort & ConfigPort): void {
+  // Lazy filesystem listing for the Link Existing and mobile input path pickers.
+  app.get('/api/filesystem/browse', async (req, reply): Promise<ApiResponse<FilesystemBrowseData>> => {
+    const { path: requestedPath, sessionId } = parseBody(FilesystemBrowseQuerySchema, req.query);
+    const roots = await resolveFilesystemPickerRoots(ctx, sessionId);
+    if (roots.length === 0) {
+      reply.code(403);
+      return createErrorResponse(ApiErrorCode.INVALID_INPUT, 'No filesystem browse roots are available');
+    }
+
+    const fallbackRoot =
+      roots.find((root) => root.label === 'Current Folder') ?? roots.find((root) => root.path === '/mnt/d') ?? roots[0];
+    const candidatePath = resolve(requestedPath ?? fallbackRoot.path);
+
+    let resolvedPath: string;
+    try {
+      resolvedPath = realpathSync(candidatePath);
+    } catch {
+      reply.code(404);
+      return createErrorResponse(ApiErrorCode.NOT_FOUND, `Folder not found: ${candidatePath}`);
+    }
+
+    const matchingRoots = roots
+      .filter((root) => isPathWithinRoot(root.path, resolvedPath))
+      .sort((a, b) => b.path.length - a.path.length);
+    const matchingRoot = matchingRoots[0];
+    if (!matchingRoot) {
+      reply.code(403);
+      return createErrorResponse(ApiErrorCode.INVALID_INPUT, 'Path is outside the allowed browse roots');
+    }
+
+    const guard = await loadAttachmentGuardConfig();
+    if (isBlockedPickerPath(resolvedPath, guard.blockedTrees, true)) {
+      reply.code(403);
+      return createErrorResponse(ApiErrorCode.INVALID_INPUT, 'Access to this folder is blocked');
+    }
+
+    try {
+      const stat = await fs.stat(resolvedPath);
+      if (!stat.isDirectory()) {
+        reply.code(400);
+        return createErrorResponse(ApiErrorCode.INVALID_INPUT, 'The browse path must be a directory');
+      }
+    } catch {
+      reply.code(404);
+      return createErrorResponse(ApiErrorCode.NOT_FOUND, `Folder not found: ${candidatePath}`);
+    }
+
+    let dirEntries;
+    try {
+      dirEntries = await fs.readdir(resolvedPath, { withFileTypes: true });
+    } catch {
+      reply.code(403);
+      return createErrorResponse(ApiErrorCode.INVALID_INPUT, 'This folder cannot be read');
+    }
+
+    dirEntries.sort((a, b) => {
+      if (a.isDirectory() && !b.isDirectory()) return -1;
+      if (!a.isDirectory() && b.isDirectory()) return 1;
+      return a.name.localeCompare(b.name);
+    });
+
+    const entries: FilesystemBrowseEntry[] = [];
+    let truncated = false;
+    for (const entry of dirEntries) {
+      if (entry.name.startsWith('.')) continue;
+      if (entries.length >= FILESYSTEM_PICKER_ENTRY_LIMIT) {
+        truncated = true;
+        break;
+      }
+
+      const visiblePath = join(candidatePath, entry.name);
+      let targetPath: string;
+      try {
+        targetPath = realpathSync(visiblePath);
+      } catch {
+        continue;
+      }
+
+      const targetRoot = roots.some((root) => isPathWithinRoot(root.path, targetPath));
+      if (!targetRoot) continue;
+
+      let type: FilesystemBrowseEntry['type'];
+      let size: number | undefined;
+      const symlink = entry.isSymbolicLink();
+      if (entry.isDirectory()) {
+        type = 'directory';
+      } else if (entry.isFile()) {
+        type = 'file';
+      } else if (symlink) {
+        try {
+          const targetStat = await fs.stat(targetPath);
+          type = targetStat.isDirectory() ? 'directory' : 'file';
+          if (type === 'file') size = targetStat.size;
+        } catch {
+          continue;
+        }
+      } else {
+        continue;
+      }
+
+      if (isBlockedPickerPath(targetPath, guard.blockedTrees, type === 'directory')) continue;
+      if (type === 'file' && size === undefined) {
+        try {
+          size = (await fs.stat(targetPath)).size;
+        } catch {
+          // The path is still selectable even when a size lookup races a change.
+        }
+      }
+      entries.push({ name: entry.name, path: visiblePath, type, size, symlink: symlink || undefined });
+    }
+
+    const parentCandidate = resolve(candidatePath, '..');
+    let parent: string | null = null;
+    if (candidatePath !== matchingRoot.path) {
+      try {
+        const resolvedParent = realpathSync(parentCandidate);
+        if (isPathWithinRoot(matchingRoot.path, resolvedParent)) parent = parentCandidate;
+      } catch {
+        // A concurrently removed parent simply disables upward navigation.
+      }
+    }
+
+    return {
+      success: true,
+      data: {
+        path: candidatePath,
+        parent,
+        root: matchingRoot.path,
+        roots,
+        entries,
+        truncated,
+      },
+    };
+  });
+
   // File tree listing
   app.get('/api/sessions/:id/files', async (req) => {
     const { id } = req.params as { id: string };

src/web/schemas.ts

@@ -49,6 +49,29 @@ const safePathSchema = z.string().max(1000).refine(isValidWorkingDir, {
   message: 'Invalid path: must be absolute, no shell metacharacters or traversal',
 });
 
+/**
+ * Filesystem picker paths are never interpolated into a shell command, so legal
+ * filename characters such as spaces, quotes, and parentheses are accepted.
+ * Containment and symlink resolution are enforced by the route after parsing.
+ */
+const filesystemPickerPathSchema = z
+  .string()
+  .max(4096)
+  .refine((p) => p.startsWith('/') && !p.includes('\0') && !p.includes('\n') && !p.includes('\r'), {
+    message: 'Path must be an absolute filesystem path',
+  })
+  .refine((p) => !p.split('/').includes('..'), { message: 'Path traversal is not allowed' });
+
+/** Query validation for the lazy, allowlisted filesystem path picker. */
+export const FilesystemBrowseQuerySchema = z.object({
+  path: filesystemPickerPathSchema.optional(),
+  sessionId: z
+    .string()
+    .max(100)
+    .regex(/^[a-zA-Z0-9_-]+$/, 'Invalid session id')
+    .optional(),
+});
+
 // ========== Env Var Allowlist ==========
 
 /** Allowlisted env var key prefixes */