# Parameter :: 1. `agent::`
Session type filter for listing operations.
**Type:** Boolean
**Fundamental Type:** Boolean flag
**Constraints:**
- Valid values: `0`, `1`, unset
- `0` = main sessions only (no agent sessions)
- `1` = agent sessions only (no main sessions)
- Unset = all session types (no filter)
**Default:** unset (all session types shown)
**Commands:** `.list`, `.projects`
**Purpose:** Distinguishes between main conversation sessions and agent sub-sessions spawned by tool calls. Agent sessions are stored as `agent-*.jsonl` files and have `isSidechain: true`. Use `agent::1` to inspect sub-agent behavior, `agent::0` to see only top-level conversations.
**Side effect:** Auto-enables `sessions::1` in `.list`.
**Examples:**
```bash
# Valid values
agent::0 # Main sessions only
agent::1 # Agent sessions only
# (unset) — all session types
# Invalid values (rejected with error)
agent::2 # Not a boolean: "agent must be 0 or 1"
agent::yes # Not a boolean: "agent must be 0 or 1"
```
**Group:** [Session Filter](../param_group/04_session_filter.md)
### Referenced Type
| Boolean | Base type | Boolean flag | `0` (false) or `1` (true); unset allowed |
### Referenced Parameter Groups
| 4 | [Session Filter](../param_group/04_session_filter.md) | Full | `session::`, `min_entries::` |
### Referenced Commands
| 2 | [`.list`](../command/02_list.md) | unset | Auto-enables `sessions::1`; filters by session type |
| 7 | [`.projects`](../command/07_projects.md) | unset | Filters sessions by type |
### Referenced User Stories
| 2 | [Find Past Conversation](../user_story/002_find_past_conversation.md) | developer |