mats

Delete on completion, not archive The alternative was preserving completed entries in an archive view; a common pattern in task managers. I chose deletion because MATS is an action queue, not a journal. Every completed technique staying in the list increases the cognitive load of scanning what still needs work. The tradeoff is real: one beta user lost a technique he wanted to reference later, which surfaced a genuine product tension between "tool for action" and "tool for memory." That tension is now a v1.1 decision, not a bug.

Constrained JSON action schema over free-form AI output The alternative was letting the AI respond conversationally and parse intent from natural language each time. I chose a strict JSON block appended at the end of every response - four action types only, one block per message - because it made the AI's database writes deterministic and auditable. Free-form output works in demos. It fails at 11pm when a user's note is ambiguous and the AI has to decide whether "worked the guard" means add a technique or advance an existing one.

Two modes with sub-tabs over a unified list The alternative was a single filterable list of all entries. I chose a hard split between TRAIN (pre and post-training workflow) and WATCH (instructional library) because the mental context is completely different; one is about tomorrow's mat session, the other is about a study backlog that spans weeks. Mixing them in one list with filters would have made the app faster to build and slower to use.