fix(files): open file paths agents print, from the terminal and the chat

A path an agent prints was already underlined in the terminal, but clicking
one opened the preview overlay on "File not found": file-content/file-raw
resolve against the session workingDir and refuse anything outside it, and the
paths agents print most (a /tmp capture, Claude's own scratchpad, another
checkout) are outside it by definition. In the response viewer those paths were
not links at all.

- openFilePreview() detects an out-of-workspace path and registers it through
  POST /api/sessions/:id/attachments first, rendering by attachment id. That is
  the surface built for live external files, so the server-side guard is
  unchanged: secret trees blocked, symlinks resolved, extension allowlist. The
  workspace routes keep refusing escapes exactly as before.
- New optional `notify` field on that route. `notify: false` suppresses only the
  attachment:detected broadcast, so a click does not also pop a card announcing
  the file already filling the screen. Default stays true for the CLI and
  publish callers.
- _linkifyFilePaths() links paths in rendered response-viewer markdown. It walks
  text nodes and builds anchors with DOM APIs (the source is model output; never
  a string rebuild of sanitized markup), skips subtrees already inside an <a>,
  and keeps the message text byte-identical so copy-code is unaffected.
- One path pattern in constants.js now feeds both the xterm link provider and
  the chat linkifier, a fresh instance per call since lastIndex is per-object
  state. It picks up /Users and /mnt roots (nothing was clickable on macOS or
  WSL), plus docx/pptx and video/audio extensions.
- .file-preview-overlay moves to z-index 5100, above the response viewer at
  5000. At its old 2000 a path clicked in the chat opened the overlay behind the
  panel it was launched from.

Verified end to end on an isolated instance, desktop and phone viewport: real
clicks in the terminal and the chat both render the image, external md and pdf
render, /etc/hosts is still refused, workspace previews unchanged.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/web/public/app.js

@@ -2004,6 +2004,17 @@ class CodemanApp {
     if (!body || body.dataset.rvBound === '1') return;
     body.dataset.rvBound = '1';
     body.addEventListener('click', async (ev) => {
+      // File path (_linkifyFilePaths): open it in the preview overlay, which
+      // resolves workspace and out-of-workspace paths alike.
+      const pathLink = ev.target.closest('a.rv-path');
+      if (pathLink) {
+        ev.preventDefault();
+        ev.stopPropagation();
+        const filePath = pathLink.dataset.path;
+        if (filePath) this.openFilePreview(filePath, this.activeSessionId);
+        return;
+      }
+
       // One-click copy: lift the raw source from the sibling <pre><code>.
       const copyBtn = ev.target.closest('.rv-copy-btn');
       if (copyBtn) {
@@ -2074,10 +2085,66 @@ class CodemanApp {
     const renderedText = document.createElement('div');
     renderedText.className = 'rv-text';
     renderedText.innerHTML = this._renderMarkdown(text);
+    this._linkifyFilePaths(renderedText);
     div.appendChild(renderedText);
     return div;
   }
 
+  /**
+   * Make absolute file paths in a rendered message clickable.
+   *
+   * The terminal's link provider never sees these: the response viewer is
+   * markdown, and a path the agent wrote as prose or inline code renders as
+   * inert text — so the file it just produced (a screenshot, a report) was one
+   * copy-paste away from being viewable instead of one click. Same pattern the
+   * terminal uses (constants.js), same destination (the file-preview overlay).
+   *
+   * Walks TEXT NODES and builds anchors with DOM APIs — never innerHTML, and
+   * never a string rebuild of already-sanitized markup: the source is model
+   * output. Subtrees already inside an `<a>` are skipped so an autolinked URL
+   * is never re-cut, and the anchor's textContent is the path verbatim, so
+   * "copy code" still yields exactly what the agent printed.
+   */
+  _linkifyFilePaths(root) {
+    if (!root || typeof document === 'undefined') return;
+    // Guarded: a stale cached constants.js must degrade to plain text, not throw
+    // out of the middle of rendering a message.
+    if (typeof absoluteFilePathPattern !== 'function') return;
+    const pattern = absoluteFilePathPattern();
+
+    // Collect first: replacing a node while the walker is positioned on it
+    // invalidates the traversal.
+    const walker = document.createTreeWalker(root, NodeFilter.SHOW_TEXT);
+    const targets = [];
+    for (let node = walker.nextNode(); node; node = walker.nextNode()) {
+      if (node.parentElement?.closest('a')) continue;
+      pattern.lastIndex = 0;
+      if (pattern.test(node.nodeValue || '')) targets.push(node);
+    }
+
+    for (const node of targets) {
+      const value = node.nodeValue;
+      const frag = document.createDocumentFragment();
+      let cursor = 0;
+      let match;
+      pattern.lastIndex = 0;
+      while ((match = pattern.exec(value)) !== null) {
+        const path = match[1];
+        if (match.index > cursor) frag.appendChild(document.createTextNode(value.slice(cursor, match.index)));
+        const link = document.createElement('a');
+        link.className = 'rv-path';
+        link.href = '#';
+        link.dataset.path = path;
+        link.title = path;
+        link.textContent = path;
+        frag.appendChild(link);
+        cursor = match.index + path.length;
+      }
+      if (cursor < value.length) frag.appendChild(document.createTextNode(value.slice(cursor)));
+      node.parentNode?.replaceChild(frag, node);
+    }
+  }
+
   _getResponseViewerAgentLabel() {
     const mode = this.sessions.get(this.activeSessionId)?.mode;
     return mode === 'codex'