feat(tui): configurable frequency or opt-out for system reminders (TodoList / permission-mode / AGENTS.md / date)

Summary

The four built-in system reminders currently have no user-facing frequency control or opt-out. Measured over 7 days of real session transcripts, they independently triggered 1,376 extra LLM turns — about 13% of all LLM calls in that window.

Measured impact (7 days, 228 real session transcripts, offline wire.jsonl analysis)

System-injected turns, classified into three buckets:

97–99% of these turns independently trigger a new LLM request (verified in wire transcripts: the reminder message is immediately followed by an llm.request with no real user message in between). Buckets B + C alone account for ≥1,238 avoidable LLM calls per 7 days (~13% of total) — and each extra turn also busts the prompt prefix cache (new turn = full uncached recompute for large prefixes).

Current behavior (source pointers, 0.40.x)

• TodoList reminder: hard-coded constants TODO_LIST_REMINDER_TURNS_SINCE_WRITE = 10 / TODO_LIST_REMINDER_TURNS_BETWEEN_REMINDERS = 10 in packages/agent-core-v2/src/features/todo/todoListReminder.ts:7-8
• permission-mode reminder: event-triggered injection, no frequency config (agent/permissionMode/injection/)
• AGENTS.md reminder: path-triggered, no config (agent/agentsMdReminder/)
• date-change reminder: startup + date-change injection, no config (features/dateChange/dateChangeService.ts)
• IAgentReminderService.register(variant, provider) has no user-facing configuration surface — each provider's cadence is baked into code

Proposed

Per-variant configuration — interval in turns, or off — e.g. in tui.toml:

[reminders]
todo_list = 50            # turns between reminders; 0 = off
permission_mode = "change-only"
agents_md = "once-per-session"
date_change = "off"

Even a single global "reminder interval multiplier / master switch" would already recover most of the cost.

Notes

• We are not asking to remove the reminders — the TodoList reminder is genuinely useful. The issue is frequency and the inability to tune it.
• The 7-day measurement method (offline wire.jsonl turn classification) is available on request.

Start with IAgentReminderService.register and the provider implementations in agent/permissionMode/injection/, agent/agentsMdReminder/, features/dateChange/dateChangeService.ts, and packages/agent-core-v2/src/features/todo/todoListReminder.ts. Trace how each reminder is injected and where tui.toml configuration is loaded. Done means users can configure or disable each listed variant and the configured cadence is respected without removing useful reminders.