# ADR 000: Temporal platform layers

- HTML version: https://robbiepalmer.me/projects/personal-engineering-platform/adrs/000-temporal-platform-layers
- Project: Personal Engineering Platform (https://robbiepalmer.me/projects/personal-engineering-platform.md)
- Status: Accepted
- Date: 2026-09-12
- Initiatives: Semi-autonomous Software Development (https://robbiepalmer.me/initiatives/semi-autonomous-software-development.md)

## Context

Shared ADR stubs made project histories read like dependency manifests and
could not preserve which default applied before a project was completed.

## Decision

Own shared defaults in this project. Record slot policy, technology selection,
and project adoption as separate dated records with half-open UTC periods.
Projects explicitly adopt each independent layer they use and keep local ADRs
for their own choices and overrides.

## Consequences

Queries can explain an effective stack and keep completed projects fixed. The
temporal records remain available to those queries, while reader-facing graph
views present direct project-to-layer and layer-to-technology relationships.

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