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# Storage Tiers Reference

**Purpose:** Define the three-tier storage model for gzkit. Every storage location in the repository is classified into one of three tiers with explicit authority boundaries.

**Authority:** [ADR-0.0.10 — Storage Tiers and Simplicity Profile](../design/adr/foundation/ADR-0.0.10-storage-tiers-simplicity-profile/ADR-0.0.10-storage-tiers-simplicity-profile.md)

**Companion:** [State Doctrine](state-doctrine.md) — three-layer trust model and authority rules

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## Three-Tier Model

| Tier | Name | Definition | Authority Boundary |
|------|------|------------|--------------------|
| **A** | Canonical | Authored markdown with YAML frontmatter + append-only JSONL ledger. The default for all governance data. | Human and agent authors via governed workflows. Changes tracked in git. No external dependencies. |
| **B** | Derived / Rebuildable | Deterministic derived indexes and caches rebuilt from Tier A sources. Permitted freely but must be rebuildable from scratch. | Automated tooling (CLI, hooks, sync commands). May be deleted and regenerated at any time without data loss. |
| **C** | External / Stateful | External runtime backends (databases, servers, protocols). | Only by explicit Heavy-lane ADR authorization. Not present today. Introduction requires its own ADR. |

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## Tier A — Canonical (Authored)

Tier A is the source of truth. All governance state originates here.

**Authority:** Human authors and governed agent workflows create and modify Tier A artifacts. All changes are committed to git.

**Storage Catalog (exhaustive):**
