# Architecture

> Tech decisions with rationale. Locked once approved — reopen explicitly.

## Stack

| Layer | Choice | Rationale |
|-------|--------|-----------|
| | | |

## Data Model

_To be defined during DEFINE phase (Pythagoras)._

## API Surface

_To be defined during DEFINE phase (Pythagoras)._

## Key Decisions

_Decisions are logged here after Pythagoras completes architecture design. Each entry includes the decision, alternatives considered, and why this choice was made._