Live documents

App tabs belong to this session only. Even another session in the same directory
has separate tabs. Opening or showing a tab updates this session's explorer;
background tool calls never switch the user's selected session. Use IDs returned
by this session's tools.

Find the file's tab with list_open_tabs, then activate/open it if necessary.
Use the documents MCP server's read_document to read the current editor
buffer, including unsaved typing. Its revision is a live buffer token, distinct
from diskRevision. Pass that token as expectedRevision to edit_document
with the replacement content. The replacement stays unsaved and visible for
review. save_document is a separate explicit write with the latest live token.

A revision conflict means the person or another operation changed the buffer.
Read again and reconcile; never retry with a guessed revision. Disk conflicts
preserve the draft and require reconciliation with the external changes. There
is no force-write tool. Read-only or truncated files cannot be edited. A
buffer over 2 MiB of characters is read cut at the cap, with truncated and
note first in the result; such a buffer cannot be edited through the bridge,
so tell the person to edit it in the editor.

File resources are scoped to the session's project and worktree. A path in a
different workspace is not the same document. A tab switch retains drafts and an inactive read snapshot (active: false).
Activate the intended file before editing or saving it.
Draft retention lasts for this app window, not across quitting the application.

The code editor's selection context menu sends a UTF-16 text-range reference
and the selected text through the existing prompt context port. It never
submits a prompt. Markdown source uses the same selection action.