yoi/work-items/closed/20260527-000020-system-reminder-injection-generalization/item.md

id	slug	title	status	kind	priority	labels	created_at	updated_at	assignee	legacy_ticket
20260527-000020-system-reminder-injection-generalization	system-reminder-injection-generalization	Generalize system-reminder history append lane	closed	task	P2	pod llm-worker history system-reminder	2026-05-27T00:00:20Z	2026-05-29T05:05:43Z	null	null

Background

session-todo-reminder established the first concrete <system-reminder>...</system-reminder> user: Task inactivity reminders are appended through pending_history_appends so the reminder is persisted in worker.history before the next LLM request. This follows the context-processing rule that new non-volatile input must be appended to history rather than injected only into request context.

The current implementation should now be generalized so future reminder producers do not each hand-roll XML tags, SystemItem construction, source labeling, cooldown/priority plumbing, or history-append integration.

This ticket is about making the system-reminder append lane a small typed facility. It is not about adding new reminder policies beyond existing Task reminders.

Requirements

• Introduce a typed internal representation for pending system reminders.
  • text/body
  • source/kind, e.g. task inactivity
  • optional priority/order key if needed
  • helper that renders the body inside <system-reminder>...</system-reminder> exactly once
• Route reminders through the existing Interceptor::pending_history_appends lane.
  • The final result must still be Item::System(SystemItem { kind: InvokeKind::SystemReminder, ... }) or equivalent current protocol type.
  • The reminder must be appended to worker.history; do not introduce hidden request-only context injection.
• Refactor session-todo-reminder to use this typed helper/facility.
  • Task reminder behavior, thresholds, cooldown, and tests should remain unchanged.
  • The helper should prevent double-wrapping if the body is already tagged, or the API should make double-wrapping impossible.
• Keep Notify / PodEvent behavior unchanged.
  • Do not merge raw notify and system reminder semantics.
  • If they share buffering mechanics, keep the public behavior and rendered tags distinct.
• Keep ordering deterministic.
  • If multiple reminder producers are added later, ordering should be explicit or stable.
  • For now, existing Task reminder order relative to Notify/PodEvent should be preserved unless there is a clear reason to change it.
• Add docs/comments near the facility explaining the rule:
  • system reminders are durable input and must be appended through history.
  • they are not transient UI notices.
  • they are not prompt-cache/context-only injections.

Acceptance criteria

• There is a typed system-reminder helper/facility rather than ad-hoc string construction in Task reminder code.
• Task inactivity reminders still appear as <system-reminder>...</system-reminder> in pending_history_appends output.
• The helper emits InvokeKind::SystemReminder / current system-reminder item kind.
• Existing Task reminder tests continue to pass.
• New focused tests cover:
  • rendering wraps body once.
  • source/kind is retained or observable where appropriate.
  • Task reminder uses the helper and remains history-append based.
  • no hidden context-only injection path is introduced.
• cargo fmt --check
• cargo check -p pod -p llm-worker -p session-store
• Relevant focused tests, e.g. cargo test -p pod reminder --no-default-features.

Out of scope

• Adding a second reminder policy.
• Changing Task reminder thresholds/cooldown.
• Changing Notify/PodEvent user-visible behavior.
• UI actionbar notices.
• Prompt text changes.
• Generic notification center or reminder scheduling service.