証拠トレースと来歴

Engram は証拠と承認済みメモリを分離し、トレースはサニタイズ済みの不変な出典を保持します。

Engram separates evidence from approved memory. A trace preserves the sanitized source record; a memory remains a human-approved instruction or reference that cites that evidence.

Approved memory contract

New approved memories use schema v3. Legacy v1 and v2 files remain readable and are never silently rewritten.

schema_version: 3
authority: instruction | reference
evidence_refs: [tr_...]
derived_from: [session-id]
revision: 1
supersedes: [older-memory-id]
superseded_by: newer-memory-id
valid_from: YYYY-MM-DD
valid_until: YYYY-MM-DD | null
last_confirmed: YYYY-MM-DD

The contract fields are schema_version, authority, evidence_refs, derived_from, revision, supersedes, superseded_by, valid_from, valid_until, and last_confirmed.

Immutable trace contract

Each traces/<trace-id>.jsonl file contains exactly one canonical record and is created exclusively, so an existing trace ID cannot be overwritten. The fields trace_id, session_id, source_hash, trust_level, sensitivity, and retention preserve identity, origin, integrity, trust, privacy, and lifecycle. authority: evidence is data only and never acts as an instruction.

{
  "trace_id": "tr_...",
  "authority": "evidence",
  "session_id": "session-id",
  "source_hash": "sha256:...",
  "trust_level": "human",
  "sensitivity": "private",
  "retention": "30d"
}

CLI and Web UI stay synchronized

engram observe and transcript hooks sanitize before persistence. The CLI prints the created trace ID, and save-session carries evidence_refs and derived_from into approved memory. Entry Web UI reads the same index and shows authority, evidence IDs, session origin, revision, validity, and supersession links in the memory detail panel.

Safety and migration

Default human capture uses trust_level: human, sensitivity: private, and retention: 30d unless configured. Expired or missing evidence blocks new approved writes. Existing observation wrappers remain review conveniences that point to traces, and initialization migrates eligible legacy wrappers once.

Promotion integrity and scope

The inbox wrapper is editable review material, not the evidence source. During save-session --file, Engram reopens the immutable trace, verifies the wrapper hash when present, and uses the trace text, session, and source metadata. Editing ## Raw Note cannot change promoted content. A trace-backed save is bound to the trace's workspace or global scope; a conflicting explicit --scope is rejected. Legacy trace and session identifiers are namespaced by scope to avoid provenance collisions.