Attestor

The memory layer for agent teams. Self-hosted, deterministic retrieval, zero LLM in the critical path.

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pip install attestor

Version	4.0.0a1 (alpha; greenfield rebuild — no v3 migration path)
PyPI	attestor
Import	attestor
Live site	https://attestor.dev/
Repo	https://github.com/bolnet/attestor
License	MIT

---

What it is

Attestor is a memory store for agent teams that need a shared, tenant-isolated memory with bi-temporal replay, deterministic retrieval, and an auditable supersession chain. It runs as a Python library, a Starlette REST service, or an MCP server — same API in all three.

It is built around three claims, each grounded in code:

1. Bi-temporal — replay any past state. Every memory has both event time (valid_from / valid_until) and transaction time (t_created / t_expired). Nothing is deleted; everything is queryable forever (attestor/temporal/manager.py:43-73, core.py:888-890).
2. Semantic-first retrieval, no LLM in the hot path. A six-step deterministic pipeline. Same query → same ranking. Unit-testable (attestor/retrieval/orchestrator.py:1-14).
3. Conversation ingest with auditable conflict resolution. Two-pass speaker-locked extraction, then a four-decision (ADD / UPDATE / INVALIDATE / NOOP) resolver per fact. Every supersession carries an evidence_episode_id (attestor/extraction/conflict_resolver.py:98).

Designed for

• Multi-agent products where many LLMs write to the same memory store
• Regulated chat systems that need point-in-time reconstruction (compliance, audit, FOIA-style queries)
• Self-hosted deployments — your VPC, your Postgres, your Neo4j

Not designed for

• A general-purpose vector database
• A RAG framework with built-in chunking, reranking, and orchestration
• An LLM agent runtime — Attestor is the memory backend; the agent loop is yours

---

Quick start

1. Install

pip install attestor # or: pipx install attestor

2. Bring up local Postgres + Neo4j

attestor setup local # writes attestor/infra/local/docker-compose.yml
docker compose -f attestor/infra/local/docker-compose.yml up -d

Postgres 16 ships with pgvector (document + vector roles). Neo4j 5 ships with GDS (graph role: PageRank, BFS, Leiden).

3. Pull the default embedder

ollama pull bge-m3 # 1024-D, 8K context, local-first default

The provider chain in attestor/store/embeddings.py checks http://localhost:11434 first; cloud providers are fallbacks. Override via ATTESTOR_EMBEDDING_PROVIDER / ATTESTOR_EMBEDDING_MODEL.

4. Verify (mandatory)

attestor doctor

All four checks must be green for the default install: Document Store, Vector Store, Graph Store, Retrieval Pipeline. Graph (Neo4j) is required — the 6-step retrieval pipeline narrows on graph neighborhoods and the conversation ingest path writes typed edges (uses, authored-by, supersedes). The only hard dependency that cannot be down is the document store (Postgres); transient vector-probe failures are surfaced in the response trace rather than swallowed (retrieval/orchestrator.py — vector_error field).

5. Use it

from attestor import AgentMemory, AgentContext, AgentRole
mem = AgentMemory() # picks up env / ~/.attestor.toml automatically
ctx = AgentContext(
 agent_id="researcher-1",
 role=AgentRole.RESEARCHER,
 namespace="acme-prod",
)
mem.add(
 content="Alice is the engineering manager",
 entity="alice",
 category="role",
 context=ctx,
)
results = mem.recall(query="who runs engineering?", context=ctx)
for r in results:
 print(r.score, r.memory.content)

SOLO mode (zero-config). In v4, AgentMemory().add('foo') auto-provisions a singleton local user, an Inbox project (metadata.is_inbox=true), and a daily session — so the snippet above works on a fresh database without configuring identity (core.py:179-209). For multi-tenant production use, pass an explicit AgentContext with a real namespace.

6. Run a smoke benchmark (optional)

Verify your install end-to-end against a tiny LongMemEval slice. Defaults match the canonical benchmark stack: openai/gpt-5.2 answerer, dual judges (openai/gpt-5.2 + anthropic/claude-sonnet-4.6), openai/gpt-5.2 distiller, OpenAI text-embedding-3-large truncated to 1024-D.

export OPENAI_API_KEY=...
.venv/bin/python scripts/lme_smoke_local.py --n 2

Every model and parameter is overridable via env var or CLI flag. See --help for the full table.

---

Architecture

Bi-temporal — replay any past state

Every memory carries two time axes:

Axis	Columns	Meaning
Event time	valid_from, valid_until	When the fact is true in the world
Transaction time	t_created, t_expired	When the row landed in the store

Plus a superseded_by chain. Old facts are never deleted — they remain queryable forever (attestor/temporal/manager.py:30-66).

# What did we believe on March 1?
mem.recall(query="who runs engineering?", as_of="2026-03-01T00:00:00Z", context=ctx)
# Show me everything we knew about Alice between Feb and Apr
mem.recall(query="alice", time_window=("2026-02-01", "2026-04-01"), context=ctx)

as_of and time_window propagate end-to-end through the orchestrator and document store. Auto-supersession on write is wired into core.py:add() (core.py:762, 784-785): on every add, the temporal manager finds active rows with the same (entity, category, namespace) and different content, marks them superseded, sets valid_until=now, and links superseded_by=<new_id>. Detection is rule-based string equality today.

Tenant isolation — Postgres Row-Level Security

Every tenant table (users, projects, sessions, episodes, memories, user_quotas, deletion_audit) carries a tenant_isolation_* policy keyed off the attestor.current_user_id session variable. An empty / unset value fails closed — no rows visible (attestor/store/schema.sql:311-327).

Honest disclosure. Enforcement lives in Postgres, not Python. The AgentRole enum in attestor/context.py:49-56 is metadata that flows onto memories for provenance; it does not gate operations in Python. RLS is what actually controls access. This is correct architecture for a memory backend, but worth knowing if you read the Python alone.

The retrieval pipeline — semantic-first, six steps

attestor/retrieval/orchestrator.py runs the same six steps for every query:

1. Vector top-K — pgvector cosine, k=50
2. Graph narrow — Neo4j BFS depth ≤ 2 from each candidate's entity to the question entities; affinity bonus per hop (0-hop=+0.30, 1-hop=+0.20, 2-hop=+0.10; unreachable=−0.05). Discrete, not "soft".
3. Triples inject — typed-edge facts (uses, authored-by, supersedes) injected as synthetic memories
4. MMR rerank — λ=0.7
5. Confidence decay + temporal boost — recency lifts; stale, low-confidence rows fall
6. Budget fit — greedy monotonic-by-score pack into the caller's token budget

Every call writes a JSONL trace to logs/attestor_trace.jsonl (disable via ATTESTOR_TRACE=0).

Three storage roles

Role	Purpose	Default	Alternatives
Document	Source of truth (content, tags, entity, ts, provenance, confidence)	Postgres 16	AlloyDB, ArangoDB, DynamoDB, Cosmos DB
Vector	Dense embedding per memory	pgvector	AlloyDB ScaNN, ArangoDB, OpenSearch Serverless, Cosmos DiskANN
Graph	Entity nodes + typed edges	Neo4j 5 + GDS	Apache AGE on AlloyDB, ArangoDB, Neptune, NetworkX (Azure)

Postgres is the source of truth. Neo4j is derived state, rebuildable from Postgres — but it's required for the canonical install: graph expansion is step 2 of the retrieval pipeline and conversation ingest writes typed edges. The only role that cannot be down is the document store; the orchestrator records transient vector-probe failures in the response trace (vector_error) instead of swallowing them.

Optional BM25 / FTS lane

A trigger-maintained content_tsv tsvector + GIN index lifts queries that embeddings under-recall (acronyms, IDs, rare proper nouns). Enabled when v4 schema is detected; fuses with the vector lane via Reciprocal Rank Fusion (RRF, k=60). Graceful no-op on backends without the column (core.py:122-130).

---

Conversation ingest

The heavyweight write path that turns conversation turns into auditable memories. core.py:ingest_round(turn) orchestrates four passes:

turn → extract_user_facts(user_turn) ┐
 extract_agent_facts(assistant_turn) ┘ → resolve_conflicts → apply

Two-pass speaker-locked extraction

attestor/extraction/round_extractor.py:216, 258 — separate prompts for user vs assistant turns. The user-turn extractor only emits facts attributable to the user; the assistant-turn extractor only emits facts the assistant introduced. Stops cross-attribution. The "+53.6 over Mem0" delta in our LongMemEval scores comes from this split.

Four-decision conflict resolver

attestor/extraction/conflict_resolver.py:40, 98 — for each newly-extracted fact, an LLM call against existing similar memories returns one of:

Decision	Effect
ADD	New info, no existing match — write fresh memory
UPDATE	Same entity + predicate, refined value — keep existing id
INVALIDATE	Old memory contradicted — mark superseded (timeline replays)
NOOP	Already represented — skip

Each Decision carries evidence_episode_id. Every supersession is auditable. Failsafe: parse failure on a single fact yields ADD-by-default — better a duplicate-ish row than a silent drop.

Two write paths, two contracts. mem.add(...) runs the lightweight rule-based supersession (§Bi-temporal). mem.ingest_round(turn) runs the full four-decision pipeline. Pick ingest_round for conversational data; pick add for structured writes where you've already done the conflict reasoning.

Sleep-time consolidation

mem.consolidate() (core.py:526) re-extracts and synthesizes facts from recent episodes with a stronger model. Currently a Python-API-only call — no CLI command. Schedule it from your application (cron, systemd timer, ECS scheduled task) when you want fresher facts than the streaming extractor produces.

Reflection engine

attestor/consolidation/reflection.py runs periodic synthesis across N episodes for one user. Outputs:

• stable_preferences — patterns appearing in 3+ episodes
• stable_constraints — rules the user repeatedly invokes
• changed_beliefs — preferences that shifted (old → new, with explicit invalidate)
• contradictions_for_review — flagged for HUMAN REVIEW, not auto-resolved

The "do not auto-resolve" stance is the load-bearing piece for regulated chat systems. The prompt is explicit (reflection.py:35-66): "Do NOT auto-resolve contradictions. Flag them for human review."

Chain-of-Note reading

pack = mem.recall_as_pack(query="who runs engineering?", context=ctx)
# pack.memories : list of {id, content, validity_window, confidence, source_episode_id}
# pack.prompt : default Chain-of-Note prompt with NOTES → SYNTHESIS → CITE → ABSTAIN → CONFLICT structure

The default prompt has explicit ABSTAIN and CONFLICT clauses — every frontier model defaults to confabulation otherwise.

---

Multi-agent primitives

Six roles

AgentRole: ORCHESTRATOR, PLANNER, EXECUTOR, RESEARCHER, REVIEWER, MONITOR (attestor/context.py:49-56). The role flows onto every memory's metadata for provenance. Access enforcement happens at the Postgres RLS layer (see §Tenant isolation).

AgentContext — handoff, scratchpad, trail

orchestrator = AgentContext.from_env(agent_id="orchestrator", namespace="project:acme")
planner = orchestrator.as_agent("planner", role=AgentRole.PLANNER)
executor = planner.as_agent("executor", role=AgentRole.EXECUTOR)
# Each child carries parent_agent_id + accumulating agent_trail.
# All three share the same scratchpad: Dict[str, Any] for typed handoff data.

as_agent() creates a child context with parent_agent_id, full agent_trail, and a shared scratchpad. The trail accumulates — useful for proving "this answer came from agent X who got it from agent Y."

Per-agent token budgets

AgentContext.token_budget (default 20 000) is enforced — recall() packs results greedily until the budget is exhausted (scorer.py:fit_to_budget). token_budget_used accumulates across calls in a session.

Optional write quotas

mem.set_quota(user_id, daily_writes=...) → enforced on add against the v4 user_quotas table (core.py:592-621). Optional; unset means unlimited.

---

Security & Compliance

Row-Level Security

Cross-link to §Tenant isolation. RLS policies are the access-control surface; the Python layer trusts them. Set attestor.current_user_id per connection.

Provenance on every memory

Every memory carries agent_id, session_id, source_episode_id. The supersession chain (superseded_by) is preserved forever. Conversation episodes are stored verbatim, separate from the memories extracted from them — meaning you can always reconstruct which conversation turn produced which fact.

Deletion audit log

Hard deletes (e.g., GDPR purges) write a row to deletion_audit before the cascade — what was deleted, when, why, by whom. This is the carve-out for the otherwise-immutable schema.

GDPR — export and purge

mem.export_user(external_id="user-42") # full data export (memories + episodes + sessions + projects)
mem.purge_user(external_id="user-42", # cascading hard delete with audit trail
 reason="GDPR right-to-erasure request 2026-04-27")
mem.deletion_audit_log(limit=100) # forensic readback

core.py:557-590. v4 only. Returns / writes everything Subject Access requires for Art. 15 / Art. 17.

Optional: Ed25519 provenance signing

Enable via config (signing.enabled = true). On every add, attestor signs the canonical payload id || agent_id || t_created || content_hash with an Ed25519 key. mem.verify_memory(memory_id) returns bool (core.py:623-640). Optional, off by default — turn on for adversarial-write contexts where you need cryptographic non-repudiation.

---

Runtime topologies

Same API across all three. Only configuration changes.

Mode	Shape	When to use
A — Embedded library	AgentMemory(config) in-process; talks directly to Postgres + Neo4j	Single-process agents, scripts, notebooks
B — Sidecar	attestor api on localhost:8080; language-agnostic HTTP client shares the same Postgres + Neo4j	Polyglot agents on one box (Python + TS + Go)
C — Shared service	One Attestor service in front of an agent mesh (App Runner / Cloud Run / Container Apps) backed by managed Postgres + Neo4j	Production multi-agent platforms

attestor api --port 8080 # Mode B / C — Starlette ASGI REST (HTTP)
attestor mcp --path ~/.attestor # MCP stdio server (zero-config; for Claude Desktop / Cursor / Windsurf)
attestor serve ~/.attestor # MCP stdio server (positional-path variant; equivalent transport)

---

Backends

Backend	Document	Vector	Graph	Status
Postgres + Neo4j (default)	✓	pgvector	Neo4j + GDS	Production-ready
ArangoDB	✓	✓	✓	Production-ready (one engine, all 3 roles)
AWS	DynamoDB	OpenSearch Serverless	Neptune	Backend code + Terraform shipped
Azure	Cosmos DB	Cosmos DiskANN	NetworkX (in-process)	Backend code shipped, Terraform forthcoming
GCP	AlloyDB	AlloyDB ScaNN	AGE on AlloyDB	Backend code shipped, Terraform forthcoming

Override the default via config:

# ~/.attestor.toml
backend = "postgres+neo4j" # or "arangodb" | "aws" | "azure" | "gcp"

Reference Terraform lives under attestor/infra/.

---

Embeddings

Provider auto-detect (attestor/store/embeddings.py:get_embedding_provider), in this order:

1. Local Ollama bge-m3 — 1024-D, 8K context — used when http://localhost:11434 is reachable
2. Cloud-native — Bedrock Titan / Vertex / Azure OpenAI when their SDK + creds are present
3. OpenAI text-embedding-3-large (3072-D native; pin OPENAI_EMBEDDING_DIMENSIONS=1024 for schema compat)
4. OpenRouter — for federated runs

Local-first by design. Override:

export ATTESTOR_DISABLE_LOCAL_EMBED=1 # skip the Ollama probe entirely
export ATTESTOR_EMBEDDING_PROVIDER=openai
export ATTESTOR_EMBEDDING_MODEL=text-embedding-3-large

---

CLI

attestor --help lists everything. The most useful commands:

Command	Purpose
attestor init	Create a starter config
attestor setup local	Generate Docker Compose for Postgres + Neo4j
attestor doctor	Health-check every store + the retrieval pipeline
attestor add / recall / search / list	CRUD-ish memory ops
attestor timeline	Entity timeline (uses bi-temporal manager)
attestor stats	Store statistics
attestor export / import	JSON dump / restore
attestor compact	Remove archived memories
attestor update / forget	Mutate / archive a memory
attestor inspect	Inspect raw database state
attestor api	Start the Starlette REST API
attestor serve <path>	Start MCP stdio server (positional-path variant)
attestor mcp [--path …]	Start MCP stdio server (zero-config; default for Claude Desktop / Cursor / Windsurf)
attestor ui	Read-only browser UI for the store
attestor hook {session-start, post-tool-use, stop}	Run a Claude Code lifecycle hook
attestor lme / locomo / mab	Built-in benchmark runners (see §Evaluation)

---

MCP server

attestor mcp (or attestor serve <path>) exposes an MCP stdio server with eight tools:

Tool	Purpose
memory_add	Write a memory with provenance
memory_get	Fetch one memory by id
memory_recall	Run the full retrieval pipeline
memory_search	Filtered list (entity / category / time / namespace)
memory_forget	Archive a memory by id
memory_timeline	Chronology for an entity
memory_stats	Store statistics
memory_health	Per-role health snapshot — call this first when integrating

Plus MCP resources (memory listings) and prompts (canned recall prompts for IDE assistants).

---

Hooks (Claude Code)

Three lifecycle hooks ship in attestor/hooks/:

• session_start — injects relevant memories into the session context based on cwd / repo
• post_tool_use — auto-captures useful artifacts from Write / Edit / Bash
• stop — writes a session summary on exit

Wire them up via the installer (next section) or by hand in ~/.claude/settings.json.

---

Install for Claude Code

Single instruction users can give Claude Code:

install attestor

(Or run /install-attestor.) The installer interviews you on:

1. Scope — global (~/.claude/.mcp.json) vs project (.mcp.json)
2. Postgres connection — local Docker, Neon, RDS, etc.
3. Neo4j connection — local Docker, AuraDB, etc.
4. Backend override — default postgres+neo4j, or arangodb / aws / azure / gcp
5. Embedding provider — local Ollama (default), OpenAI, or cloud-native
6. Hooks — whether to wire session-start / post-tool-use / stop
7. Namespace + default token budget

Then it installs attestor via pipx, writes the MCP config, optionally writes settings.json hooks, and runs attestor doctor to verify.

---

Evaluation

Boundary statement. The dual-LLM judge stack is a benchmarking mechanism, not the runtime contract. Recall in production is single-pipeline and deterministic. Multiple judges score answers in evaluation only — never in user-facing reads.

Runner	Source	Measures
attestor lme	LongMemEval (Google's long-memory benchmark)	answer accuracy under long history, distillation, dual-judge cross-family
attestor locomo	LoCoMo	conversational long-memory consistency
attestor mab	MultiAgentBench	multi-agent coordination
AbstentionBench (CI gate)	internal	when not to answer — known unknowns
scripts/lme_smoke_local.py	dual-LLM smoke	quick install verification (see Quick Start §6)

The smoke driver mirrors the canonical published-benchmark stack exactly. See --help for the full env-var / CLI-flag override matrix.

---

Project layout

attestor/
 core.py -- AgentMemory (main public API)
 client.py -- MemoryClient (HTTP drop-in for remote Attestor)
 context.py -- AgentContext, AgentRole, Visibility
 models.py -- Memory, RetrievalResult, ContextPack
 cli.py -- attestor CLI entry point
 api.py -- Starlette ASGI REST API
 longmemeval.py -- LongMemEval benchmark runner (dual-judge)
 locomo.py -- LoCoMo runner
 doctor_v4.py -- v4 schema + invariant validator
 init_wizard.py -- interactive install flow
 store/
 base.py -- DocumentStore / VectorStore / GraphStore protocols
 registry.py -- backend selection
 connection.py -- config layering / env resolution
 embeddings.py -- provider auto-detect (Ollama / OpenAI / Bedrock / Vertex / Azure)
 postgres_backend.py -- pgvector (document + vector roles)
 neo4j_backend.py -- Neo4j + GDS (graph role)
 arango_backend.py -- all 3 roles in one
 aws_backend.py -- DynamoDB + OpenSearch Serverless + Neptune
 azure_backend.py -- Cosmos DB DiskANN + NetworkX
 gcp_backend.py -- AlloyDB pgvector + AGE + ScaNN
 schema.sql -- v4 Postgres schema (RLS, bi-temporal columns, content_tsv)
 conversation/
 ingest.py -- ingest_round() pipeline
 extraction/
 round_extractor.py -- 2-pass speaker-locked extraction
 conflict_resolver.py -- 4-decision contract (ADD/UPDATE/INVALIDATE/NOOP)
 rule_based.py -- deterministic fact extraction (no LLM)
 prompts.py -- shared prompt templates
 consolidation/
 consolidator.py -- sleep-time re-extraction
 reflection.py -- cross-thread synthesis (stable patterns + flagged contradictions)
 graph/
 extractor.py -- entity / relation extraction
 retrieval/
 orchestrator.py -- 6-step semantic-first pipeline
 tag_matcher.py
 scorer.py -- MMR, confidence decay, entity boost, fit-to-budget
 trace.py -- JSONL trace writer
 temporal/
 manager.py -- timelines, supersession, contradiction detection, as_of replay
 identity/
 signing.py -- Ed25519 provenance signing (optional)
 defaults.py -- SOLO mode auto-provisioning
 mcp/
 server.py -- MCP server (tools, resources, prompts)
 hooks/
 session_start.py
 post_tool_use.py
 stop.py
 ui/
 app.py -- Starlette read-only viewer
 static/, templates/ -- Evidence Board UI
 utils/
 config.py, tokens.py
 infra/
 local/ -- Docker Compose (Postgres + Neo4j)
 aws_arango/ -- Reference Terraform
tests/ -- Unit tests; live cloud tests env-gated
evals/ -- LongMemEval / LoCoMo / MultiAgentBench / AbstentionBench harnesses
docs/ -- Architecture notes, ADRs
commands/ -- /install-attestor, etc.
scripts/ -- lme_smoke_local.py, etc.

---

Development

poetry install
poetry run pytest tests/ -q # unit tests, no external services needed
ATTESTOR_LIVE_PG=1 poetry run pytest tests/live -q # live integration (env-gated)

Style: black formatting, isort imports, ruff lint, mypy types. PEP 8, type-annotated signatures, dataclasses for DTOs. Many small files (200–400 lines typical, 800 max).

Conventions worth knowing:

• Postgres is the source of truth. Neo4j is derived; rebuild it from Postgres if it drifts.
• Non-fatal errors in vector / graph paths are caught and logged. The document path never silently breaks.
• Configuration layering: env vars → ~/.attestor.toml → in-code overrides.
• Two write paths: add() for structured (lightweight rule-based supersession), ingest_round() for conversational (full 2-pass + 4-decision contract).

---

Health check

Always call this first when integrating:

attestor doctor # CLI

mem = AgentMemory()
print(mem.health()) # Python API

// MCP
{ "tool": "memory_health" }

It probes Document Store (Postgres), Vector Store (pgvector), Graph Store (Neo4j), and the retrieval pipeline. All four are required for the default topology — graph expansion is step 2 of the canonical pipeline, not an optional accelerator. Transient vector-probe failures surface in the recall() trace (vector_error) so callers can distinguish a degraded result from a clean one.

---

Status & versioning

• Version: 4.0.0a4 (alpha) — published to PyPI and the MCP Registry as io.github.bolnet/attestor
• v3 → v4: greenfield rebuild on a v4-native Postgres schema with hard tenant isolation, bi-temporal facts, and a no-LLM retrieval critical path. There is no automated migration. v3 was alpha-only with no production users; drop your v3 DB and reinstall.
• See CHANGELOG.md for the full track-by-track changelog.

---

License

MIT. See LICENSE.