docs: Added documentation for the new spawnable_agents whitelist property

Agents.md

@@ -533,20 +533,25 @@ see the [code-reviewer](https://github.com/Dark-Alex-17/coyote/blob/main/assets/
 
 ## Spawning Configuration
 
-| Setting                     | Type    | Default       | Description                                                                    |
-|-----------------------------|---------|---------------|--------------------------------------------------------------------------------|
-| `can_spawn_agents`          | boolean | `false`       | Enable this agent to spawn child agents                                        |
-| `max_concurrent_agents`     | integer | `4`           | Maximum number of child agents that can run simultaneously                     |
-| `max_agent_depth`           | integer | `3`           | Maximum nesting depth for sub-agents (prevents runaway spawning chains)        |
-| `inject_spawn_instructions` | boolean | `true`        | Inject the default spawning instructions into the agent's system prompt        |
-| `summarization_model`       | string  | current model | Model to use for summarizing long sub-agent output (e.g. `openai:gpt-4o-mini`) |
-| `summarization_threshold`   | integer | `4000`        | Character count above which sub-agent output is summarized before returning    |
-| `escalation_timeout`        | integer | `300`         | Seconds a sub-agent waits for an escalated user interaction response           |
+| Setting                     | Type              | Default       | Description                                                                    |
+|-----------------------------|-------------------|---------------|--------------------------------------------------------------------------------|
+| `can_spawn_agents`          | boolean           | `false`       | Enable this agent to spawn child agents                                        |
+| `spawnable_agents`          | list of strings   | *unset*       | Whitelist of agent names this agent may spawn. Omit for unrestricted access.   |
+| `max_concurrent_agents`     | integer           | `4`           | Maximum number of child agents that can run simultaneously                     |
+| `max_agent_depth`           | integer           | `3`           | Maximum nesting depth for sub-agents (prevents runaway spawning chains)        |
+| `inject_spawn_instructions` | boolean           | `true`        | Inject the default spawning instructions into the agent's system prompt        |
+| `summarization_model`       | string            | current model | Model to use for summarizing long sub-agent output (e.g. `openai:gpt-4o-mini`) |
+| `summarization_threshold`   | integer           | `4000`        | Character count above which sub-agent output is summarized before returning    |
+| `escalation_timeout`        | integer           | `300`         | Seconds a sub-agent waits for an escalated user interaction response           |
 
 **Example configuration:**
 ```yaml
 # agents/my-orchestrator/config.yaml
 can_spawn_agents: true
+spawnable_agents:
+  - explore
+  - coder
+  - oracle
 max_concurrent_agents: 6
 max_agent_depth: 2
 inject_spawn_instructions: true
@@ -555,6 +560,43 @@ summarization_threshold: 3000
 escalation_timeout: 600
 ```
 
+### Restricting which agents can be spawned (`spawnable_agents`)
+
+By default (i.e. when `spawnable_agents` is omitted), any agent installed under
+`<coyote-config-dir>/agents/` is spawnable.
+
+To restrict, add a list of agent names. Only agents whose directory name
+appears in the list will be spawnable. Anything else the agent tries to
+spawn via `agent__spawn` is rejected with an actionable error, and hidden
+from `agent__list_available` output.
+
+```yaml
+can_spawn_agents: true
+spawnable_agents:
+  - explore
+  - coder
+  - oracle
+```
+
+Use this to:
+- **Scope an orchestrator to a focused set of specialists.** An orchestrator
+  that only needs `explore`/`coder`/`oracle` won't accidentally spawn
+  unrelated personal agents in your config directory.
+- **Enforce team boundaries.** In a shared/CI setup, restrict what a given
+  agent is allowed to invoke.
+- **Prevent recursion cycles.** Combined with `max_agent_depth`, an explicit
+  whitelist gives you fine-grained control over the spawn graph.
+
+Notes:
+- Match is exact and case-sensitive. Use directory names as they appear on
+  disk.
+- `spawnable_agents: []` means literally nothing spawnable (rare but valid).
+- Graph agents (with a `graph.yaml`) always ignore `spawnable_agents`; they
+  statically declare their spawn targets via `agent` nodes in the graph
+  itself.
+- Override at runtime via env var: `<AGENT_NAME>_SPAWNABLE_AGENTS` as a JSON
+  array (e.g. `SISYPHUS_SPAWNABLE_AGENTS='["explore","coder"]'`).
+
 ## Spawning & Collecting Agents
 
 When `can_spawn_agents` is enabled, the agent receives tools for spawning and managing child agents: