Architecture Decision Records

Significant, hard-to-reverse design decisions are recorded here as ADRs: the context at the time, the decision, and its consequences. The first four are backfilled from the replacement design; new decisions get a new numbered file in this folder.

ADR	Decision	Status
0001	Aggregate-first storage — raw rows do not survive the chunk pass	Accepted
0002	Declarative YAML catalog as the source of behavior	Accepted
0003	Closed expression AST instead of embedded code	Accepted
0004	Chunk ledger with computation hashes for idempotent ingestion	Accepted
0005	One metric-owned adaptive heatmap; old aliases are rejected	Accepted
0006	Strict versioned catalog with no compatibility translation	Accepted

Writing a New ADR

Copy the section structure of any existing record (Status, Context, Decision, Consequences), number it sequentially, add it to the table above, and land it in the same PR as the change it justifies. Superseded decisions stay in place with status "Superseded by NNNN".