# capture_since

Source: https://libtmux.org/en/py/latest/mcp/tools/capture_since/

> Capture new tmux terminal scrollback since the previous cursor.

MCP is in development

Server behavior and tool contracts may change. Tool availability depends on the server configuration.

Capture new tmux terminal scrollback since the previous cursor.

Use for observation-first workflows: tailing a shell, watching a long-running command, or repeatedly checking a tmux workspace pane without re-sending the same visible screen every turn. The first call with `cursor=None` returns the current visible pane and an opaque cursor. Later calls pass that cursor back and receive only rows written or rewritten after the cursor, as long as tmux still retains the required scrollback history.

If tmux history was cleared or trimmed before the cursor anchor, the tool returns the current visible pane with `lines_missed=True` and a fresh cursor. Malformed cursors, cursors for a different pane, pane death, and pane respawn fail with `ExpectedToolError` so agents do not accidentally observe the wrong process.

[All Python tools](../) · [JSON](../capture_since.json) · [Source](https://github.com/tmux-python/libtmux-mcp/blob/4daddc0dfca96c43bf521d818bf91564e1434760/src/libtmux_mcp/tools/pane_tools/__init__.py#L106)

## Arguments

* `cursor` optional

  Opaque cursor returned by a prior \`\`capture\_since\`\` call. When omitted, the tool captures the current visible screen and starts a new cursor.

  Default: `null`.

* `max_bytes` optional

  Maximum UTF-8 bytes to return across \`\`lines\`\`. Defaults to \`\`CAPTURE\_SINCE\_DEFAULT\_MAX\_BYTES\`\`. Pass \`\`None\`\` to disable byte truncation.

  Default: `128000`.

* `max_lines` optional

  Maximum number of lines to return. Defaults to \`\`CAPTURE\_SINCE\_DEFAULT\_MAX\_LINES\`\`. Pass \`\`None\`\` to disable line truncation.

  Default: `500`.

* `pane_id` optional

  Pane ID (e.g. '%1'). Optional when \`\`cursor\`\` is supplied; the cursor carries the original pane id.

  Default: `null`.

* `session_id` optional

  Session ID (e.g. '$1') for pane resolution.

  Default: `null`.

* `session_name` optional

  Session name for pane resolution.

  Default: `null`.

* `socket_name` optional

  tmux socket name.

  Default: `null`.

* `window_id` optional

  Window ID for pane resolution.

  Default: `null`.

## Schemas

The schema defines required fields, nested values, defaults, and validation constraints.