Architecture Decision Records

This document tracks significant architectural decisions and patterns in the Super Productivity codebase. When making changes that affect these patterns, reference this document and update it if needed.

Active Patterns & Decisions

1. dueDay/dueWithTime Mutual Exclusivity Pattern

Status: ✅ Active (since commit 400ca8c1, 2026-01-29)

Decision: The task.dueDay and task.dueWithTime fields are mutually exclusive in new data. When setting dueWithTime, dueDay must be cleared (set to undefined). When reading, dueWithTime takes priority over dueDay.

Rationale:

• Prevents state inconsistency bugs where both fields had conflicting values
• Single source of truth for task scheduling
• Simpler state management

Implementation:

• Writing: Clear dueDay when setting dueWithTime (in meta-reducers)
• Reading: Check dueWithTime first; only check dueDay if dueWithTime is not set (in selectors)
• Legacy Data: Old data with both fields works via priority pattern (no migration needed)

Key Files:

• task.model.ts - Field definitions with JSDoc
• task-shared-scheduling.reducer.ts - Write implementation
• work-context.selectors.ts - Read pattern
• planner.selectors.ts - Read pattern
• task.selectors.ts - Read pattern

When to Update This Pattern:

• Adding new date/time scheduling fields
• Modifying task scheduling logic
• Working with task selectors that check due dates

2. TODAY_TAG Virtual Tag Pattern

Status: ✅ Active (established pattern)

Decision: TODAY_TAG (ID: 'TODAY') is a virtual tag whose membership is determined by task.dueWithTime or task.dueDay, not by task.tagIds. The tag's taskIds field stores only the ordering of tasks, not membership.

Key Invariant: TODAY_TAG.id must NEVER be added to task.tagIds

Rationale:

• Uniform move operations across all tags (virtual and regular)
• Single source of truth for "today" membership (date fields, not tagIds)
• Self-healing ordering (stale entries automatically filtered)
• Natural integration with planner (which uses date fields)

Related: Uses the dueDay/dueWithTime mutual exclusivity pattern (Decision #1)

Key Files:

• tag.const.ts - TODAY_TAG definition
• work-context.selectors.ts - Membership computation
• task-shared-helpers.ts - Invariant enforcement

When to Update This Pattern:

• Adding new virtual tags
• Modifying tag membership logic
• Working with today's task list

How to Use This Document

When Making Architectural Changes

1. Before implementing: Check if your change affects any active pattern
2. During implementation: Follow the documented patterns
3. After implementation: Update this document if you've:
   • Changed an existing pattern
   • Added a new architectural pattern
   • Made a decision that affects future development

When to Add a New Decision

Add a new decision record when:

• The decision affects multiple files/modules
• Future developers need to understand "why" not just "what"
• The pattern needs to be followed consistently across the codebase
• The decision prevents a specific class of bugs

Decision Record Template

### N. [Pattern/Decision Name]

**Status**: ✅ Active | 🚧 Draft | ⚠️ Deprecated | ❌ Superseded

**Decision**: [One-sentence summary of the decision]

**Rationale**:

- [Why was this decision made?]
- [What problems does it solve?]

**Implementation**:

- [How is it implemented?]
- [Key techniques or patterns used]

**Documentation**: [Link to detailed docs]

**Key Files**: [List of primary files implementing this pattern]

**When to Update This Pattern**: [Scenarios when someone should review/update this]

Related Documentation

• docs/sync-and-op-log/ - Operation log architecture
• docs/long-term-plans/ - Future architectural plans

Commit Reference

When committing changes related to these patterns, reference this document and the specific decision:

feat(tasks): implement feature X

Uses dueDay/dueWithTime mutual exclusivity pattern (ARCHITECTURE-DECISIONS.md #1)