Provider semantics

Federation normalizes the retrieval envelope, not the meaning of the underlying record. Every hit keeps a provider ID, external record identity, source kind, provenance, timestamps, and provider metadata that passed the adapter’s bounds.

Compatibility model

Provider ID	Source model preserved	Published adapter boundary
`mem0`	Memory IDs, text, metadata, and user/agent/run scope	Inject a Mem0 client and explicit namespace mapper. Mem0 add processing may be asynchronous, so a queued write is not a settled mirror.
`langgraph`	Long-term store items and namespaces	Inject a LangGraph store. Checkpoints are thread execution state and never become facts automatically.
`zep`	User graph context, episodes, entity nodes, and relationship edges	Inject a Zep client. Graph ingestion can be asynchronous; exact-key semantics must not be inferred from graph search.
`graphiti`	Episodes, temporal facts, nodes, edges, validity windows, and provenance	Inject a caller-owned transport. Episode lineage is retained when the transport supplies it.
`letta`	Core memory blocks and recent messages as different kinds	Inject a Letta client. Blocks map to `pinned_context`; messages map to `message`. The adapter does not claim Letta archival retrieval.
`openai_agents`	Ordered session items and conversation history	Inject an Agents SDK session. Session items remain conversation state, not durable user facts.

These distinctions follow the providers’ official models:

Mem0 memory operations distinguish add, search, update, delete, entities, and asynchronous events.
LangGraph persistence stores graph state as checkpoints, while its memory guide separates thread state from cross-thread stores.
Zep’s graph model distinguishes episodes, entity nodes, and relationship edges.
Graphiti models temporal facts with validity and episode provenance.
Letta memory blocks are persistent, always-visible agent context; archival memory is a separate retrieval surface.
OpenAI Agents SDK sessions maintain ordered conversation history across runs.

Result rules

A result is always source-labelled.
Source-local relevance scores stay source-local. Do not compare 0.8 from one provider with 0.8 from another as if they shared a calibration.
Source-qualified duplicates may be grouped for display, but provenance is never discarded.
Contradictions remain visible. Federation does not silently pick a universal truth.
Each source reports ok, timed_out, unavailable, or error. The aggregate status is partial only when at least one source succeeds, and failed when none succeeds. Provider failures are returned with per-source errors rather than thrown, so callers must inspect result.status and result.sources; failed is never disguised as an empty success.

Candidate is not personal memory

The hosted plane uses portable candidate records so developers can opt into Praxa storage later. A candidate is not promptable Praxa personal memory and carries no AHCE consent. Any future promotion requires a separate authenticated owner-review contract and canonical erasure fencing. The hosted vocabulary is deliberately closed. It accepts message, fact, summary, episode, pinned_context, document, entity, and edge. It rejects LangGraph checkpoints: a checkpoint is execution state, not a portable durable-memory record. A custom provider ID is available for a caller-defined adapter only when its records still satisfy the same bounded envelope.

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Core Concepts

Releases

Provider semantics

Compatibility model

Result rules

Candidate is not personal memory

​Compatibility model

​Result rules

​Candidate is not personal memory

Compatibility model

Result rules

Candidate is not personal memory