Echo Archive Policy

• Layer 0 — Raw Echo Archive
• Layer 1 — Structured Echo Archive
• Layer 2 — Curated High-Value Echoes
• Layer 3 — Echo Digest
• Layer 4 — Permanent Attestation Archive

Legacy v1 echoes are preserved in echoes/records/ with legacy_schema: true and record_kind: "legacy_record". New echoes must use the v3 schema (/api/echo-record-schema.v3.json).