# Froglet Storage Profile

Status: non-normative supporting document

The kernel does not mandate a storage engine.
This document records the logical invariants and the current reference storage
profile used by the implementation.

## 1. Logical Invariants

Implementations should preserve four logical classes of data:

- immutable artifact documents
- an append-only local feed log
- mutable query indexes derived from retained evidence
- settlement and execution evidence needed to justify terminal receipts

The important invariants are:

- artifact immutability
- durability before acknowledgment
- logical append-only feed sequencing
- rebuildable derived indexes
- receipt accountability preservation
- pruning and archival safety
- engine-neutral exportability

Any engine is acceptable if those invariants hold.

## 2. Reference Storage Split

The reference implementation currently maps those invariants into three explicit storage classes:

- `artifact_documents`
- `artifact_feed`
- `execution_evidence`

The same implementation may also keep mutable convenience tables such as:

- `jobs`
- `quotes`
- `deals`
- `payment_tokens`
- `events`

Those convenience tables are not the authoritative evidence layer.

An implementation may map the same logical split onto another storage engine as
long as these logical stores and evidence invariants remain intact.

## 3. Evidence Retention

For every locally opened or locally served deal, the implementation should retain enough material to reconstruct:

- the signed artifacts by hash
- local feed order for retained entries
- the quote -> deal -> receipt chain
- settlement identifiers and final settlement states
- timestamps relevant to expiry and accountability

## 4. Export and Archival

The reference implementation may expose archive/export helpers for local accountability and migration.

Those exports should preserve, at minimum:

- retained artifact documents
- corresponding feed entries
- retained execution evidence
- retained settlement transport material such as `invoice_bundle` records

Archive layout is intentionally not part of the kernel contract.