crons

Crons & Reminders

This workspace maintains a persistent cron registry at memory/crons.json — the source of truth for every scheduled task across sessions. The SessionStart hook reconciles it against the live harness; the PostToolUse hook captures ad-hoc CronCreate/CronDelete calls automatically.

All writes to the registry go through one script: bash ${CLAUDE_PLUGIN_ROOT}/skills/crons/writeback.sh <subcommand>. Never edit memory/crons.json by hand.

CronCreate / CronList / CronDelete are deferred tools — call ToolSearch(query="select:CronList,CronCreate,CronDelete") once per session before invoking them. The parameter name is cron, not schedule. Always pass durable: true (forward-compat for when the upstream flag is fixed).

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⛔ FORBIDDEN — read before touching anything

These rules are non-negotiable. Violating any of them silently breaks reminders for the user.

1. Never compute cron expressions yourself. LLMs miscompute timezones inconsistently (sometimes UTC, sometimes local — verified empirically). Claude Code's cron daemon uses the host's LOCAL time. The only correct way to produce a cron expression is to call bash $CLAUDE_PLUGIN_ROOT/bin/cron-from.sh .... The helper does deterministic epoch arithmetic and returns cron + human-readable confirmation in the host's TZ. (Enforced: a PreToolUse hook blocks CronCreate with exit 2 unless the cron expression matches a cron-from.sh output from the last 120s. If the mode you need isn't covered by relative/absolute/recurring, use cron-from.sh passthrough "<cron>" as an escape hatch.)

2. Never use ScheduleWakeup for user-facing commitments. ScheduleWakeup is intra-session only (dies on /exit). Any reminder, alert, or recurring task the user requests via chat MUST go through CronCreate(durable: true). The reconcile hook keeps it alive across restarts.

3. Never tell the user the reminder is "session-only", "may not arrive", or any equivalent degraded-persistence phrasing in any language. With this skill, every commitment is durable. If you genuinely cannot create the cron (e.g. helper failed), surface the error to the user — don't silently degrade to a verbal-only promise.