Provenance

Where a memory came from and how much to believe it: the turn or agent that produced it (source_id), who actually asserted it (speaker), and the weight that assertion carries (authority).

Why it matters in a memory layer

Three separate jobs, and collapsing any two of them loses something you cannot reconstruct later.

source_id is what makes deletion possible at all — a memory written without one cannot be removed on request, because nothing identifies what to remove, and neither can a derived summary be traced back to the episode it consumed.

speaker and authority are what stop hearsay becoming fact. "My colleague thinks she's moving to Berlin" and "I'm moving to Berlin" produce the same sentence after extraction; only provenance distinguishes them. Flatten the distinction and a third party's guess silently becomes a first-party belief that will outrank the truth.

Distinct from namespace: namespace answers where is this filed and who may read it, provenance answers who said it and do we believe them. A memory can be perfectly visible and correctly disbelieved.