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February 21st, 2026

Architecture Shift: Pre-calculated Task Instances & Backend Parity Today, we completely shifted the responsibility of complex recurrence scheduling out of the opaque native Android layer into a transparent, mathematically identical structure across our JavaScript frontend, local SQLite database, and Convex backend.
  • Migrate to pre-calculated JavaScript task instances architecture:
    • Added an instances table to the local SQLite DB (Version 3) with indexing on start/end times.
    • Created lib/scheduler.ts to statically calculate exactly 1 year of timestamps from recurrence rules using dayjs.
    • Updated final.tsx to batch insert 365 generated instances into the local DB automatically upon task creation or update.
    • Updated useTaskActions.ts to explicitly delete all associated instances when a local task is deleted from commits.tsx, preventing ghost alarms.
    • Enhanced DbDebugFab in _layout.tsx to fetch and pretty-print explicitly generated task instance timestamps (with titles) to improve debug visibility.
  • Synchronize local SQLite instances explicitly with Convex backend:
    • Updated backend create and update mutations to return explicit instances rows.
    • Removed the duplicated client-side recurrence calculation (lib/scheduler.ts).
    • Updated final.tsx to insert the actual 365 backend instances directly into SQLite instances, preserving their exact Convex instance _id and timestamps.
    • Bumped the local DB version to 4, adding an explicit taskId column to instances via ALTER TABLE to avoid frontend JOIN requirements.
    • Updated useTaskActions.ts deletion logic using a nested SQL lookup to explicitly clear local instances during a task deletion.
This architectural change ensures a mathematically identical 1:1 parity between Convex backend instances and Android local SQLite alarms, entirely eliminating local clock drift and opaque scheduling bugs.