feat(create): warn on --no-onboard for post-discovered-id agents (Issue #68)

.agents/skills/multi-agent-mux-create/SKILL.md

@@ -170,7 +170,7 @@ bash .agents/skills/multi-agent-mux-create/scripts/create_session.sh --workspace
 | `--herdr-session` (`--herdr-server`) | Isolated herdr server name |
 | `--herdr-workspace` | herdr workspace label recorded in the registry (a label only, never a socket) |
 | `--submit-job PROMPT` | Register a delegated job with this prompt and send it to the new agent |
-| `--onboard` / `--no-onboard` | Submit the onboarding job (default: on) |
+| `--onboard` / `--no-onboard` | Submit the onboarding job (default: on); with `--no-onboard` an agent whose id appears only after its first turn (adapter `id_lifecycle`) records none until then and blocks a same-folder create of its type (#63) - create warns |
 | `--auto-trust` / `--no-auto-trust` | Answer a start-up directory-trust dialog or leave it to a human (`MAM_AUTO_TRUST`; default: answer) |
 | `--isolate` / `--no-isolate` | Legacy, no-op |