docs: audit package limitations on current stack

packages/support/subagent-mock/README.md

@@ -13,8 +13,14 @@ Load it as a plugin (functional shape: `name`/`inject`/`Config`/`apply`, no defa
 | `name` | `mock` | Registry name to register the provider under. |
 | `reply` | `mock subagent reply` | The scripted child's final answer text. |
 | `stopReason` | `completed` | The stop reason `result` settles with. |
-| `capabilities` | all `true` | Which start-time capabilities (`outputSchema`/`depthLimit`/`toolFilter`) the provider advertises. |
+| `capabilities` | all `true` | Which start-time capabilities (`outputSchema`/`depthLimit`/`toolFilter`/`persona`) the provider advertises. |
 | `inheritsParentContext` | `false` | The context contract to declare; `true` exercises the fork-shaped tool wording in consumer tests. |
 | `structured` | `{ reply }` | Structured value surfaced when a request carries an `outputSchema` and the capability is on. |
 
 A `cancel()` issued before `result` settles flips the stop reason to `aborted`, so the cancellation path is observable.
+
+## Known Limitations and Deferred Work
+
+- **Scripted provider only** — it does not run a model, create a child agent, or exercise real prompt/tool-loop behavior.
+- **One immediate synthetic outcome per run** — it models no multi-turn, streaming, readiness delay, or subprocess transport behavior.
+- **`dispose()` is a no-op** — lifecycle tests using it prove consumer control flow, not resource teardown or quiescence of a real backend.