Follow up to: #3582504 _**NOTE: Before working on this issue, verify it's still relevant and makes sense.**_ **Description:** Two default selection behaviors should be settled before RC1 because changing them later would alter observable results. Conditional subcontexts currently include all conditional children when no AI provider is configured, which can unexpectedly expand token usage. Global items are capped in first-seen/ascending-ID order, which makes older items win arbitrarily when the cap is reached. **Scope:** - Add a configurable conditional subcontext fallback with a safe default such as `required_only`. - Update `AiContextSubcontextResolver` to use the fallback when no provider is configured or provider selection fails. - Sort global context items deterministically, preferably by `changed DESC` with ID tie-breaker, before applying `max_global_items`. - Add/update config schema, default config, admin UI if needed, and tests. **Acceptance criteria:** - No-provider conditional subcontext behavior no longer includes all conditional children by default. - Provider failure behavior is deterministic and documented. - Global items over the cap are selected by intended ordering, not first loaded ID. - Tests cover fallback behavior and global item ordering. [x] AI Assisted Issue