Single model mode
- Added the
singleModelMode setting (global, project-overridable). When enabled, every subagent invocation runs on the parent session's model.
- Bypasses per-invocation model overrides, per-agent model lists, agent-definition model fields, spawn-time probes, and the dispatch arbiter.
- Prepends a
[WARNING: ...] note to the subagent's output whenever a requested model selection was ignored — including one identical to the parent's. No warning when nothing requested a model.
- Fails loudly at spawn if the parent session has no model.
- Exposed in the TUI (
/settings), dashboard Settings, and settings.json.
Implemented in PR 518, resolving issue 517.
