feat(FN-3777): add create_agent and delete_agent tools

Adds agent creation and deletion tools to the pi extension, with engine-side implementation in `agent-tools.ts`, core store integration for agent lifecycle management, and corresponding tests and documentation updates across the workspace.

Fusion-Task-Id: FN-3777

packages/cli/skill/fusion/SKILL.md

@@ -30,7 +30,7 @@ Mission → Milestone → Slice → Feature → Task
 - **Task tools** — `fn_task_create`, `fn_task_update`, `fn_task_list`, `fn_task_show`, `fn_task_attach`, `fn_task_pause`, `fn_task_unpause`, `fn_task_retry`, `fn_task_duplicate`, `fn_task_refine`, `fn_task_archive`, `fn_task_unarchive`, `fn_task_delete`, `fn_task_plan`
 - **GitHub tools** — `fn_task_import_github`, `fn_task_import_github_issue`, `fn_task_browse_github_issues`
 - **Mission tools** — `fn_mission_create`, `fn_mission_list`, `fn_mission_show`, `fn_mission_delete`, `fn_milestone_add`, `fn_slice_add`, `fn_feature_add`, `fn_slice_activate`, `fn_feature_link_task`
-- **Agent tools** — `fn_agent_stop`, `fn_agent_start`, `fn_list_agents`, `fn_delegate_task`, `fn_agent_show`, `fn_agent_org_chart`
+- **Agent tools** — `fn_agent_stop`, `fn_agent_start`, `fn_agent_create`, `fn_agent_delete`, `fn_list_agents`, `fn_delegate_task`, `fn_agent_show`, `fn_agent_org_chart`
 - **Skills tools** — `fn_skills_search`, `fn_skills_install`
 - **Insight tools** — `fn_insight_list`, `fn_insight_show`, `fn_insight_run_list`, `fn_insight_run_show`
 - **Other tools** — `fn_web_fetch`, `fn_research_run`, `fn_research_list`, `fn_research_get`, `fn_research_cancel`, `fn_research_retry`

packages/cli/skill/fusion/references/engine-tools.md

@@ -30,6 +30,8 @@ These tools are **not** part of the user-invokable extension surface. They are i
 | `fn_delegate_task` | triage, executor, heartbeat | Create and assign a new task to a specific agent | `agent_id` (string), `description` (string), `dependencies?` (string[]) |
 | `fn_get_agent_config` | executor, heartbeat | Read full config for a direct-report agent | `agent_id` (string) |
 | `fn_update_agent_config` | executor, heartbeat | Update config fields for a direct-report, non-ephemeral agent | `agent_id` (string), optional: `soul`, `instructions_text`, `instructions_path`, `heartbeat_procedure_path`, `heartbeat_interval_ms`, `heartbeat_timeout_ms`, `max_concurrent_runs`, `message_response_mode` |
+| `fn_agent_create` | executor, heartbeat | Create a non-ephemeral direct-report agent | `name` (string), `role` (string), optional: `soul`, `instructions_text`, `instructions_path`, `reportsTo`, `heartbeat_interval_ms`, `heartbeat_timeout_ms`, `max_concurrent_runs`, `message_response_mode` |
+| `fn_agent_delete` | executor, heartbeat | Delete a non-ephemeral direct-report agent | `agent_id` (string), optional: `force` (boolean), `reassign_to` (string) |
 | `fn_send_message` | executor, step-session, heartbeat | Send inbox messages to agents/users | `to_id` (string), `content` (string), `type?` (`agent-to-agent` \| `agent-to-user`), `reply_to_message_id?` (string) |
 | `fn_read_messages` | executor, step-session, heartbeat | Read inbox messages | `unread_only?` (boolean), `limit?` (number) |
 

packages/cli/skill/fusion/references/extension-tools.md

@@ -263,6 +263,33 @@ Start a stopped agent — resumes its execution. Transitions the agent from paus
 |-----------|------|----------|-------------|
 | `id` | string | ✓ | Agent ID to start (e.g., agent-abc123) |
 
+### fn_agent_create
+
+Create a new non-ephemeral agent.
+
+| Parameter | Type | Required | Description |
+|-----------|------|----------|-------------|
+| `name` | string | ✓ | Agent name |
+| `role` | string | ✓ | Agent role/capability |
+| `soul` | string | — | Agent personality/identity text |
+| `instructions_text` | string | — | Inline custom instructions |
+| `instructions_path` | string | — | Path to instructions markdown |
+| `reportsTo` | string | — | Manager agent ID |
+| `heartbeat_interval_ms` | number | — |  |
+| `heartbeat_timeout_ms` | number | — |  |
+| `max_concurrent_runs` | number | — |  |
+| `message_response_mode` | union | — |  |
+
+### fn_agent_delete
+
+Delete a non-ephemeral agent.
+
+| Parameter | Type | Required | Description |
+|-----------|------|----------|-------------|
+| `id` | string | ✓ | Agent ID to delete |
+| `force` | boolean | — | Force delete when holding checkout |
+| `reassign_to` | string | — | Optional replacement agent for assigned tasks |
+
 ### fn_list_agents
 
 List all available agents in the system. Shows each agent's name, role, state, personality (soul), and current assignment. Use this to discover which agents exist and what they specialize in before delegating work.

packages/cli/skill/fusion/references/fusion-capabilities.md

@@ -50,6 +50,8 @@ All skill/extension tool invocations in this catalog use the public `fn_*` names
 | `fn_feature_link_task` | Link a feature to a fn task for implementation. Updates the feature status to 'triaged' and associates it with the task. |
 | `fn_agent_stop` | Stop a running agent — pauses its execution. Transitions the agent from running/active to paused state. |
 | `fn_agent_start` | Start a stopped agent — resumes its execution. Transitions the agent from paused to active state. |
+| `fn_agent_create` | Create a new non-ephemeral agent. |
+| `fn_agent_delete` | Delete a non-ephemeral agent. |
 | `fn_list_agents` | List all available agents in the system. Shows each agent's name, role, state, personality (soul), and current assignment. Use this to discover which agents exist and what they specialize in before delegating work. |
 | `fn_delegate_task` | Create a new task and assign it to a specific agent for execution. The task goes to 'todo' and will be picked up by the target agent on their next heartbeat cycle. Use fn_list_agents first to find available agents and their capabilities. |
 | `fn_agent_show` | Show detailed information about a single agent, including their role, state, position in the org hierarchy (reports-to, direct reports), skills, and current assignment. |