inspeximus 1.51.0

The self-correcting memory layer for AI agents: when a fact is corrected, Inspeximus serves the new value and resists the old one resurfacing. Zero-dependency single file + MCP server — value-ranked recall, per-type decay, consolidation, revert, and tamper-evident erasure.

inspeximus

"We have inspected" — the medieval charter that recites an earlier one word for word and attests it unaltered. The self-correcting memory layer for AI agents.

Correct a fact once and it stays corrected: inspeximus serves the new value and refuses to let the old one creep back — deterministically, with no LLM on the write path. Extracted from an autonomous research OS that has run it daily over 10,000 notes.

pip install inspeximus → import inspeximus · PyPI · Hugging Face · DOI · Homepage · MIT · v1.48.0

If inspeximus's saved you some time, a ⭐ would mean a lot — it's how other people find it. Thank you!

Built by Rastislav Drahoš — extracted from Agora, an autonomous research OS that runs it daily.

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Install into Claude Code in one line

/plugin marketplace add DanceNitra/inspeximus
/plugin install inspeximus@inspeximus

That registers this repository as a plugin marketplace and installs the MCP server, which then starts with uvx --from "inspeximus[mcp]" inspeximus-mcp and keeps its store in .inspeximus/memory.json inside the project. Nothing to configure by hand, and nothing to install globally.

Prefer the manual route? pip install "inspeximus[mcp]" and point your client at inspeximus-mcp — the extra matters, because the core library is deliberately zero-dependency and the MCP server is the one piece that needs a dependency.

What you install, and what it does that others don't

A mem0 alternative built the opposite way: deterministic, not an LLM extracting facts on every write — a memory that keeps a correction corrected and can show, with an offline-verifiable receipt, what it erased. At a glance:

	inspeximus	mem0 / cognee / Zep · Graphiti
Write path	deterministic — no LLM	LLM extraction on every add()
Correction (a fact changes)	keyed supersession serves current truth; a restated stale value can't creep back (echo_guard); revert()	LLM re-extract / bitemporal invalidation
Verifiable erasure	signed, content-free tombstone + an offline-verifiable receipt	delete() — unverified
Tamper-evident record-keeping	hash-linked receipts + a signed anchor, verified offline	SOC 2 audit logs (not cryptographic) / none
EU AI Act / GDPR evidence	inspeximus compliance overlay + audit bundle	not framed
Dependencies	zero — one file	server / DB / vector / graph stack
MCP server	yes (one-command install)	varies

To our knowledge the only agent-memory library that ships verifiable erasure and tamper-evident record-keeping (a scan of nine products — details; honest: Zep has a real SOC 2/HIPAA surface, just not verifiable erasure or AI-Act framing). And it doesn't cost you recall — the measured integrity number below is a number no competitor we scanned publishes.

New — the EU AI Act compliance-evidence layer for agent memory

When the AI Act's high-risk obligations start applying (2 Dec 2027 for standalone Annex III systems, 2 Aug 2028 for Annex I product-embedded ones — deferred from 2 Aug 2026 by Regulation (EU) 2026/1744, the Digital Omnibus on AI, in force 27 Jul 2026), a provider of one -- and, for log-keeping, its deployer under Art. 26(6) -- has to be able to show things about what its agent remembers. The Act requires automatic event logging over the system's lifetime (Art. 12) and log retention (Art. 19); accuracy, robustness and cybersecurity including resilience to attempts to alter performance (Art. 15); and GDPR Art. 17 gives data subjects a right to erasure. None of those articles say memory, provenance or tamper-evidence — mapping them onto agent memory is our reading, not the text, and this is not legal advice.

Of the agent-memory libraries we read (mem0, Zep/Graphiti, Cognee, Letta, LangMem — source at main, 24 Jul 2026), none ship verifiable erasure with a receipt or tamper-evident record-keeping; inspeximus does, as a drop-in overlay rather than a rebuild. We have not surveyed the whole field, and smaller projects exist that we have not read — tell us if we have missed one and we will correct this.

inspeximus compliance --out report.html     # article-labelled evidence, live counts from your store
inspeximus audit-build --out bundle.json    # hand an auditor the bundle; they verify it offline (audit-verify)

Evidence, not certification; the memory slice only, and the obligations bind the provider/deployer, not the library. → docs/AI_ACT.md

Every claim below is checked by a script you can run

python claims_audit.py          # downloads the published wheel from PyPI and audits THAT

It fetches the released artifact, prints its sha256, and runs each claim on it — never on the working tree. The write-path claim is enforced rather than asserted: sockets are disabled for the duration, so a write that reached for a model would fail the check instead of passing it quietly. Claims about other systems are listed separately and marked untestable here; verifying those means running those systems, so they are never counted as passing.

auditing : inspeximus-1.24.1-py3-none-any.whl
13 passed · 0 FAILED · 0 skipped · 5 not testable here

This exists because the exercise pays for itself: the first time we ran a README sentence against the published wheel, it failed. Erasure did delete the record and scrub the bytes, but plain forget() left no receipt, so the store's own verify_writes() reported the deletion as out-of-band — flagging a legitimate API call as tampering. Fixed in 1.24.0, with a regression probe, and the audit now covers it. The tightened audit then caught a second one: forget_subject() was writing two receipts per record, one of them with the wrong reason (fixed in 1.24.3).

On certification. There is no certification body for an agent-memory library, and anyone claiming otherwise is selling a logo. SOC 2 and ISO 27001 certify organisations running services; no scheme certifies that a Python file deletes what it says it deletes. So instead:

• governance_audit.py attacks the strongest claim here — tell it to forget everything about a subject and it can prove it — across three scenarios and three repeats each: erasure through derived_from lineage, absence from the records, from recall under several phrasings, and from the bytes of every file the store wrote including sidecars; exactly one receipt carrying the caller's stated basis; tamper detection; survival across a reload; unrelated records intact; and an identical end state on every run.
• The audit must be able to fail. GOV_FALSIFY=1 skips the erasure, and CI requires the run to report CLAIM BROKEN. A green falsification control would mean the checks measure nothing, so it is treated as a build failure.
• It runs where we cannot touch it — every push and daily, on Linux, Windows and macOS, against both this source and the wheel published on PyPI. The badge above is the result. If it is red, believe the badge and not this paragraph.

What that does not certify: this store, not your vector index, prompt logs or backups; the receipt proves the act of deletion, never the content; and an operator holding the receipt key can forge receipts, so anchor the chain head externally if your adversary is the operator. Those limits are in the docstrings too, and they are the reason the word "certified" does not appear anywhere else on this page.

Witness network — the operator-adversarial layer

"Anchor the chain head externally" has a concrete, runnable form. anchor() emits a signed tree head; on its own it catches a rewrite on one timeline (verify_consistency), but a compromised host can still show a different history to a different client (a split-view / fork). Independent witnesses that co-sign the head close that — an honest witness refuses to co-sign a fork, so a client requiring k-of-n cannot be shown a forked head that reaches threshold. This is the one operator-adversarial guarantee a free single-party receipt structurally cannot give — it needs an independent third party — and it needs no LLM, no GPU, no graph database.

# each independent party runs one witness (stdlib http server, zero framework):
python -m inspeximus.witness_server --port 9700 --state witnessA.json   # prints its pubkey

from inspeximus import Inspeximus
from inspeximus.witness_pool import collect_cosignatures, http_witness, Witness

anchor = store.anchor()                                  # signed tree head of the whole history
witnesses = [http_witness("http://hostA:9700"), http_witness("http://hostB:9701"), Witness()]
out = collect_cosignatures("my-store", anchor, witnesses)
ok = Inspeximus.verify_cosigned_anchor(anchor, out["cosignatures"],
                                       witnesses=[...pubkeys...], threshold=2)["ok"]
# a forked head -> honest witnesses REFUSE (surfaced in out["refused"]) -> it never reaches threshold;
# Inspeximus.detect_split_view(...) turns two co-signed inconsistent heads into a cryptographic fork proof.

See examples/07_witness_pool.py for the full end-to-end (honest k-of-n, honest extension, a refused fork). No competitor ships external witnessing; witnesses persist their per-store last-signed head so the refusal survives a restart.

Portable audit bundle — hand an auditor one file they verify offline

EU AI Act Article 12 (record-keeping / logging; applies to high-risk systems from 2 Dec 2027, Annex III) and GDPR Art.17/30 ask an operator to produce, on demand, a tamper-evident log of what the system recorded, what changed, and what was erased — and to let an independent party verify it. inspeximus already computes every piece; audit_bundle serialises them into one content-free artifact with a standalone verifier that needs neither the live store nor the receipt key:

inspeximus --receipts remember "retention policy is 90 days" --key policy::retention --object 90d
inspeximus audit-build --out bundle.json        # operator exports (content-free: hashes + surrogate ids, no text)
inspeximus audit-verify bundle.json             # auditor runs this — offline, exit 0 = PASS, 1 = FAIL

audit-verify re-walks the entire write and erasure history from genesis, confirms every hash and prev-link, checks the tips/counts against the signed anchor, and fails on any post-export alteration — with nothing but the file. Pass --witnesses <pubkeys> to also verify external co-signatures (the operator-adversarial check from the witness network above). It is a tamper-evident record-keeping artifact, not a compliance certification — it proves the acts (a write with this commitment at T; a record erased at T for request R) and their append-only integrity, never the content (a hash of PII is still PII). Full demo: examples/09_audit_bundle.py.

Why inspeximus — the one thing no other agent memory does

Every mainstream agent-memory library puts an LLM on the write path: it calls a model to extract, summarize, or build a graph every time you store something. mem0 runs LLM fact-extraction on add() by default; Zep/Graphiti runs LLM entity/edge extraction on every add_episode(). That one choice is why their stored state is non-deterministic, costs a model call per write, and can silently drop a fact.

inspeximus has no LLM on the write path. Storing a fact is a deterministic, zero-cost operation — and that is what makes three things possible the mainstream libraries don't offer:

What that costs, measured on someone else's benchmark. On the MemOps long-context scenarios (24 scenarios, ~50 sessions each), ingesting one scenario through mem0's default pipeline took 519–917 s of LLM extraction (median 606 s, n=24); inspeximus's write path made zero model calls. Read the rest before quoting that: on the same run, answer accuracy was statistically indistinguishable — inspeximus 0.593, a naive keep-all store 0.592, mem0 0.544, with every bootstrap CI crossing zero. So the honest claim is same answers, no write-time model cost, not better answers. About 2% of mem0's extraction calls failed to parse and those memories are missing from its store, which handicaps it slightly. MemOps is published by MemTensor, who also make a competing system. Harness, pre-registration and the full result: agora/agora_output/lab/memops.

• Corrections that stick. Write a new value for a key and it supersedes the old one; echo_guard blocks a later restatement of the retired value from resurfacing. No config, no model call. Honest scope: the guard engages on keyed or extractor-derived assertions (the shipped extractors derive the key from raw text); a free-text write that nothing keys is stored as an independent record and ranks on its own.
• Revert on command. m.revert(key) rolls a corrected fact back to its predecessor. Of the leading systems we checked — mem0, Zep/Graphiti, Letta, Cognee, Memobase, MemoryScope, LangMem, txtai — none exposes a revert-to-predecessor command (mem0's history() is a read-only log; Graphiti invalidates but never un-invalidates; Letta has no undo).
• Deletes the value, not just the pointer. forget_subject removes the value from inspeximus's records (subject
  • its derived_from lineage) and leaves a content-free, tamper-evident signed receipt — so what remains is a proof-of-deletion, not the data. Since 1.24.0 every deletion path leaves that receipt, including plain forget(ids=…, where=…); before that only forget_subject and forget_pii did, so a record removed with forget() was erased correctly but unaccounted-for, and verify_writes() reported it as an out-of-band deletion — the store flagging its own legitimate API call as tampering. Pass request_id= / basis= to forget() to bind the reason into the receipt's committed hash. Most agent-memory libraries instead retain the deleted value by design: mem0 keeps it in its SQLite history table (a full reset() purges it); Graphiti stamps the old edge invalid_at and keeps it. For secure erasure at rest (against raw-disk/backup forensics — which a plaintext store of ANY library, inspeximus included, does not give you) use an encrypted store + shred() (NIST SP 800-88 crypto-erasure: destroy the key and every at-rest copy dies).

	LLM on write	corrections stick	revert to predecessor	deleted value retained?
inspeximus	no — deterministic	✅ supersession + echo_guard	✅ revert(key)	✅ no — value scrubbed, content-free receipt (+ shred() for at-rest)
mem0	yes (by default)	LLM decides ADD/UPDATE	✗ history is read-only	✗ kept in the history table by design
Zep / Graphiti	yes	temporal invalidation	✗ no un-invalidate	✗ invalidated edge retained
Letta / MemGPT	yes	LLM rewrites the block	✗ no undo	✗

(Every competitor cell was checked against that project's current source/docs — see the integrity benchmark, which also names each system that shares an individual property. Cryptographic deletion receipts do exist in purpose-built provenance systems like Engram and Heartwood; the claim here is scoped to mainstream agent-memory libraries.)

The mechanism underneath — no LLM on the write path — is the part a competitor can't copy without abandoning its extraction design. That is the moat.

And it doesn't cost you recall

Integrity would be hollow if inspeximus retrieved worse. It doesn't. On the standard LOCOMO benchmark (full set, n=1536), with the built-in tuned recipe (a semantic embedder + hybrid recall + a soft speaker prefilter), inspeximus's retrieval-recall@25 is 0.78 (a supporting turn is retrieved) / 0.65 (all supporting turns) — top-tier, and measured the honest way: LLM-free and reproducible, with no LLM judge to inflate it. Run it: python inspeximus/probes/retrieval_recall_locomo.py.

(We deliberately don't headline an LLM-judged end-to-end QA score. Those are judge-dependent and not comparable across harnesses — mem0 reports 66.9% and Zep 71.2% under their own judges — so a cross-system "we win" claim would need running them through this harness, which we haven't done. What we publish is our own reproducible number.)

Every number in this README traces to a runnable probe in inspeximus/probes/. Nothing is asserted that you can't reproduce.

Quickstart (2 minutes)

pip install inspeximus          # zero required dependencies

from inspeximus import Inspeximus

m = Inspeximus("memory.json")                      # persists to JSON; drop the path for pure in-memory
m.remember("The API rate limit is 1000 req/min", key="api::rate_limit")
m.recall("what is the rate limit")            # -> ["The API rate limit is 1000 req/min"]

# Correction is first-class: writing the same key supersedes the old value — no config, no LLM call.
m.remember("The API rate limit is 5000 req/min", key="api::rate_limit")
m.recall("rate limit")                        # -> ["...5000 req/min"]  (only the current value)
m.revert("api::rate_limit")                   # roll back to the predecessor, on command
m.history("api::rate_limit")                  # full audit trail, oldest to newest

New in 1.11.0: ready-made write-path extractors (regex_extractor, deterministic; make_llm_extractor, opt-in) that can derive a key from text without an explicit one, and a first-class LangChain integration (from inspeximus.integrations.langchain import InspeximusRetriever — a retriever that never hands a superseded fact back to your chain). pip install "inspeximus[langchain]".

Honest scope of regex_extractor (measured 2026-07-20, corrected from an earlier overclaim). It keys clean declarative statements — "My ZIP code is 94107", "Alice's email is …", "The API rate limit is 500 rps". It does not reliably key natural conversational prose: measured on an external dialogue corpus (the MemOps dataset, arXiv 2607.12893) it derived a key for 5.2% of sentences (1,037 of 19,851 across six transcripts), and — the part that matters — it does not hold a stable key across a real correction chain, because "my official title … was Junior Data Analyst" and "so my current title is Data Analyst" yield different keys that never meet. On raw chat transcripts, supersession therefore mostly does not fire and inspeximus behaves as a verbatim store. If you control the write, pass key= explicitly — that is the path where corrections-stick, revert and the erasure guarantees actually hold. (This README previously said the extractors exist "so supersession engages over free text"; that was too strong. See CHANGELOG 1.23.1, which also fixes a real data-loss bug found in the same measurement.)

Give your agent this memory in 60 seconds (MCP)

Using Claude Code? One command registers inspeximus as your agent's memory (uv fetches it, nothing else to install):

claude mcp add inspeximus -e INSPEXIMUS_PATH=~/.inspeximus_memory.json -- uvx --from "inspeximus[mcp]" inspeximus-mcp

Claude Desktop / Cursor / any MCP client — add to your MCP config (claude_desktop_config.json, .cursor/mcp.json, …):

{
  "mcpServers": {
    "inspeximus": {
      "command": "uvx",
      "args": ["--from", "inspeximus[mcp]", "inspeximus-mcp"],
      "env": { "INSPEXIMUS_PATH": "~/.inspeximus_memory.json" }
    }
  }
}

Your agent now has remember / recall / history — and corrections that stick: when a fact is superseded, recall serves the current value, a restated stale value can't resurrect it (echo_guard), and revert / route undo a correction on an unmarked "go back". recall returns compact records by default (drops internal fields; get(id) / neighbors(id) for detail on demand). Full tool list below.

For coding agents: stop resurrecting an API a refactor already deleted

The single most common way memory fails inside a coding loop: a refactor renamed or removed a function, but the model re-emits the old call because the old signature is still all over its context. That is keyed supersession + an echo check — inspeximus's core competence — shaped for code, as three MCP tools:

from inspeximus import Inspeximus
from inspeximus.code_guard import deprecate_symbol, symbol_status, check_code
mem = Inspeximus(path=".inspeximus/memory.json")

deprecate_symbol(mem, "db.query", "db.execute", reason="query() removed in 3.0; execute() returns a cursor")
symbol_status(mem, "db.query")          # -> {'verdict':'superseded','replacement':'db.execute', ...}
check_code(mem, generated_snippet)      # -> [{'symbol':'db.query','replacement':'db.execute','occurrences':1}, ...]

check_code scans a whole generated snippet and flags every deprecated symbol it resurrects (whole-identifier match, most-used first; empty = clean) so the agent rewrites before returning code. Over MCP the same three are deprecate_symbol / symbol_status / check_code. Deterministic table lookup — no LLM, no embedding similarity guess, no new storage. Full runnable demo: examples/08_code_guard.py. This is the vendor-abandoned need behind Claude Code #14227 ("don't resurrect the old API after a refactor"), served by the primitive inspeximus already ships.

Enforce it in CI, not just in the loop. The same guard is a shell command that exits non-zero when a deprecated symbol reappears — drop it into a pre-commit hook or a CI step so a human (or an agent) cannot merge a resurrected API:

inspeximus deprecate db.query db.execute --reason "query() removed in 3.0"   # record the refactor once
inspeximus check-code src/**/*.py                                            # exits 1 with file:line on any resurrection

# .pre-commit-config.yaml  (point INSPEXIMUS_PATH at a store committed to the repo, e.g. .inspeximus/memory.json)
- repo: https://github.com/<owner>/inspeximus
  rev: v1.39.0
  hooks: [{ id: inspeximus-check-code }]

Commit the store (.inspeximus/memory.json) so every clone shares the refactor history; the guard is a deterministic token scan, so the same commit is a pass or a fail on every machine.

Jump to: Correction (measured) · Governance & erasure · Org-wide erasure receipt · Install · MCP server · Shell CLI · Framework integrations · The four operations · Five rules · Provenance & receipts · Threat model

Use

The full API reference — every method, argument and return shape, with runnable examples — lives in docs/API.md. The four operations you actually need are further down this page; everything else is there when you need it.

Framework integrations

Adapters for LangGraph, CrewAI, LangChain, LlamaIndex, AutoGen and the rest, with copy-paste snippets: docs/INTEGRATIONS.md.

Compliance-aware out of the box. Every class-based adapter — LangGraph InspeximusStore, CrewAI InspeximusStorage, LangChain InspeximusRetriever / InspeximusChatMessageHistory, LlamaIndex InspeximusMemoryBlock, AutoGen InspeximusMemory, OpenAI-Agents InspeximusSession, Haystack InspeximusDocumentStore, ADK InspeximusMemoryService — mixes in ComplianceMixin, so the same object your agent writes memory to also produces the EU AI Act evidence — store.compliance_report(), store.compliance_check(), store.audit_bundle(), store.retention(...). Pass receipts=True for the tamper-evident record-keeping chain those reports evidence. See docs/AI_ACT.md. (Pydantic AI is the one exception: it exposes a function toolset, inspeximus_toolset(store), so there is no adapter object — call the evidence operations on the store you passed in.)

Use it as an MCP server (any Claude / Cursor / agent client)

inspeximus ships an MCP stdio server so any MCP-compatible agent can use it as long-term memory — remember (with a per-type decay prior), value-ranked recall, consolidate, consolidate_clusters, contradictions, value_by_cohort, forget (verified erasure). Correction is first-class over MCP too: revert / route undo a correction on an unmarked "go back", and the read-path review layer observe / reopened / resolve_reopened (1.9.2–1.9.5) reopens a settled record for steward review on a corroborated contradiction (a lone restatement stays an echo, never an auto-change). The MCP remember exposes key (deterministic supersession) plus object / reaffirm, and the server runs with echo_guard ON by default (0.6.11) so a corrected fact stays corrected even if the old value is re-stated later — the failure mode a plain keyed/add-based store shows on RAMR's ECHO-RESISTANCE (keyed-without-guard 0.00, a real add-based system 0.57, guard 1.00). Set INSPEXIMUS_ECHO_GUARD=0 to disable. Install and run the server straight from PyPI (the [mcp] extra pulls the MCP SDK; the core library stays dependency-free):

pip install "inspeximus[mcp]"     # the library + the MCP server SDK
inspeximus-mcp                          # speaks MCP over stdio

Register it with any MCP client — Claude Code (.mcp.json), Claude Desktop (claude_desktop_config.json), Cursor, Windsurf, Codex, Gemini. Zero-setup with uvx (installs on first run):

{
  "mcpServers": {
    "inspeximus": {
      "command": "uvx",
      "args": ["--from", "inspeximus[mcp]", "inspeximus-mcp"],
      "env": { "INSPEXIMUS_PATH": "./inspeximus_memory.json" }
    }
  }
}

Or, after pip install "inspeximus[mcp]", with the console script directly:

{
  "mcpServers": {
    "inspeximus": {
      "command": "inspeximus-mcp",
      "env": { "INSPEXIMUS_PATH": "./inspeximus_memory.json" }
    }
  }
}

For semantic recall, point it at any OpenAI-compatible embeddings endpoint via INSPEXIMUS_EMBED_URL / INSPEXIMUS_EMBED_MODEL / INSPEXIMUS_EMBED_KEY; with none set it uses the lexical fallback. The agent then calls recall(query) before reasoning and remember(fact) as it learns — its memory is value-ranked and append-only, not a recency buffer. If INSPEXIMUS_EMBED_MODEL contains nomic (nomic-embed-text is asymmetric — see its model card; like E5's passage:/query:), inspeximus auto-applies its required task prefixes — search_document: for stored text, search_query: for the query (opt out with INSPEXIMUS_NOMIC_PREFIX=0). Omitting them was simply using the model wrong; with prefixes on, our own reinforcement-controlled re-measure lands recall_any@1 at 0.397 on one LoCoMo config (n=1536, deterministic retrieval-recall — an upper bound, not end-to-end QA; a self-comparison, not a cross-system claim; the earlier 0.19→0.29 delta was contaminated by a since-fixed recall-reinforcement confound — see the 1.15.0 CHANGELOG correction). In the library, pass a separate Inspeximus(embed=…, embed_query=…) for any asymmetric embedder. If you use persist_vectors=True, also pass Inspeximus(embed_id="…") (a recipe fingerprint): when it changes, inspeximus re-embeds the persisted vectors once so a new-space query can't silently mis-match old vectors.

Compact recall + progressive disclosure (1.14.0). Over MCP, recall returns a compact projection — {id, text, score, value, tags} — dropping internal bookkeeping fields the model doesn't reason over, and k is hard-capped (INSPEXIMUS_MAX_K, default 50), so a recall drops cheaply into the prompt. Full text is kept by default; snippet truncation is opt-in (snippet_chars>0) — off by default on purpose, since truncating a hit could cut off a corrected value past the boundary and defeat the echo-guard. Pull detail on demand: get(id) returns one full record, neighbors(id, k) a bounded local expansion (excludes self). recall(full=True) returns complete records. token_report(query, k) is a deterministic, no-LLM (~chars/4) payload-size estimate comparing the compact projection to the full records for the same k hits — an apples-to-apples sizing aid, not a whole-store comparison and not a measured token saving. None of this is novel — it's standard MCP/RAG context-economy practice (progressive disclosure / small-to-big retrieval); inspeximus never emitted embedding vectors.

The four operations

op	what it does
remember(text, tags, value, mtype, key)	append-only raw capture, absolute UTC time, never edited; mtype ∈ {episodic, semantic, procedural} sets the decay prior (events fade fast, durable facts slow, rules barely). Optional key = a deterministic (subject, relation) supersession key: a new value retires every active record with the same key — no similarity threshold, no LLM — so recall never serves the stale value (bi-temporal: a back-filled earlier value can't overwrite the current one)
recall(query, k, where=…)	value-ranked retrieval: relevance × value, decayed by the memory's per-type half-life (access resets the clock), so important durable memories beat both merely-similar and stale ones. Optional where = a metadata pre-filter (the cheap filter-before-you-rank lever): field → scalar / list / operator ($gte $lte $gt $lt $in $nin $ne $contains), matched top-level then meta, ALL fields AND-ed — e.g. a hard time-range where={"valid_from":{"$gte":t0,"$lte":t1}} or a closed-set entity where={"speaker":{"$in":[…]}}. Measured to beat retriever choice on LoCoMo (probes/locomo_metadata_prefilter.py); it's a HARD filter, so on lossy/predicted extraction keep it loose (a wrong filter hard-deletes the answer). Reinforcement is relevance-weighted (a bullseye hit reinforces value more than one that squeaked into top-k, so a weak-but-frequent false positive can't go immortal); a repeatedly-recalled episodic memory graduates to semantic only when corroborated — by an earned outcome, or by ≥2 distinct canonical sources (entity-resolved before counting, so sybil variants of one origin — Wikipedia / wikipedia.org / a full URL — collapse to one and can't mint durability); and a memory whose source was later contradicted is provenance-demoted + flagged stale_derived
consolidate(keep)	the dream pass: flag universal-matcher hubs, link near-duplicates, apply the state-toggle guard (a polarity clash supersedes, doesn't merge), supersede the low-value surplus — only adds a derived layer
consolidate_clusters(threshold)	cluster-triggered consolidation: consolidate a semantic cluster only once it's grown past threshold — sparse topics keep their raw episodes, dense ones don't grow unbounded
contradictions()	flag mutually-incompatible related memories (similarity-gated) for human review
forget(ids, where)	the one op that truly deletes (the rest is append-only): hard-removes the matched records and scrubs their ids from every survivor's links + toggle pointers + the vec/token caches, so a forgotten memory can't resurface via recall, a consolidation link, or the dream pass. For erasure / right-to-be-forgotten, poison removal, or a hard correction — measured 15/15 on a verified-forgetting severe-test

"Delete that" — then check what the lineage says survived

Erasing the record is the easy half. The half that bites is the summary built from it, which no longer resembles the subject's data at all — so a text-match delete walks straight past it and the fact is back next session. forget_subject() already cascades along lineage; erasure_audit() is the separate question of what survived:

inspeximus erasure-audit --subject user-42     # exit 1 when declared-lineage residue remains

scanned 1 record(s) for subject 'user-42'
  coverage  1/1 record(s) declare lineage (ratio 1.0)
  RESIDUE  3 finding(s) tied to a deliberate erasure:
    [subject_still_attributable] e3cf66c984
      still attributable to 'user-42' (status=active)
    [dangling_lineage] e3cf66c984
      declares parent 03dad5493e, which was deliberately erased
    [taint_without_origin] e3cf66c984
      carries inherited source 'user42', but no surviving record claims it: the origin was erased, this derivative was not
  limit  this is evidence about what the store RECORDED, not proof that no copy of the material remains
  limit  a derivative whose writer never declared derived_from carries no taint and is invisible here; read `coverage` before trusting a pass
  limit  covers THIS store only -- not your vector index, prompt logs, model weights or backups
  limit  does not discharge an erasure obligation; a party that stops declaring lineage always looks clean

Read coverage before the verdict — the tool prints it first on purpose. Every structural check walks declared derived_from edges. A store whose writers never threaded lineage has no edges to walk, so it would report nothing while having inspected nothing. That is a completely different statement from "checked, nothing found", and collapsing the two into one reassuring boolean is how a deletion audit becomes a false assurance. So when nothing is declared the verdict is unaudited, never a pass.

Housekeeping deletions are separated out too: capacity eviction and the consolidation keep-budget hard-delete for size reasons, and would otherwise masquerade as erasure residue in any bounded store. They are reported as advisory with the reason attached, and never counted. What lands in residue is tied to a deliberate erasure — one carrying a request id or a real basis, not the generic default housekeeping leaves behind.

What this is and isn't. It is evidence about what the store has recorded, not proof that no copy of the material remains — and it does not discharge an erasure obligation. Three limits ship with every answer, in a limits field a renderer cannot quietly drop:

• taint propagates along declared edges only, so a summary whose writer never declared its parents is invisible to every structural check. We ship that as a test asserting we do not find it. It is the overtainting/undertainting trade-off argued for dynamic taint analysis by Schwartz, Avgerinos & Brumley (IEEE S&P 2010); that is program analysis, not lineage, so we borrow the trade-off, not a result;
• it covers this store only — never your vector index, prompt logs, model weights or backups;
• it reads metadata the writer supplied, so a party that stops declaring lineage will always look clean.

The optional --value text scan is reported separately and labelled a heuristic, because matching text proves neither presence (a paraphrase carries the fact without the string) nor absence.

Not a new idea: this is DELF-style deletion-correctness auditing (Cohn-Gordon et al., DELF: Safeguarding deletion correctness in Online Social Networks, USENIX Security 2020) applied to an agent-memory store, with the orphan/dangling half being classical referential-integrity checking.

Where did this fact come from?

You rarely reach for provenance going forwards. You reach for it backwards — when someone says "delete that", and the fact is back next session because a summary that three other episodes still support had absorbed it. provenance() answers that in one call, for one fact, in the order an auditor asks:

m.provenance(key="billing-api::auth")     # or provenance(id="…") for one record

fact      billing-api::auth
  now       oauth2  [active]
  source    adr-014  (not attested)
  lineage   primary observation
  trust     claimed
  history   2 value(s), 1 retired
              api-keys  ->  retired by keyed_lww
              oauth2  ->  active
  integrity content matches; attribution matches; chain ok; unsigned the write receipt

Same answer from the shell (inspeximus provenance billing-api::auth, --json for the full object) and over MCP (provenance). It assembles what the store already carries, rather than adding a new claim layer:

field	what it answers	built from
origin	the declared source; the taint it inherited transitively through summarization, so a derived note is never mistaken for a first-hand one; whether an origin attestation bound it to a verified key; the acting user/agent/session	source + derived_from + attested_key
trust	the evidence grade — claimed → corroborated → verified → settled, earned from corroboration and external ratifications and never settable by the writer	grade()
timeline	every value the fact has held, its validity interval, and which policy retired each one (keyed_lww, echo_guard, state_toggle, …)	history()
integrity	whether the record still matches the content and sources its write receipt committed to — so an out-of-band edit that rewrites a record's source without also rewriting the receipts sidecar is caught — plus the current anchor to pin the answer against	verify_attribution() + anchor()

What it does not prove, returned in a limits field so a caller rendering this cannot quietly drop it: this is tamper-evident, not correct — a source that was already wrong when it was written is committed faithfully and nothing here can tell. And unsigned (the default), the receipt chain only catches an editor who cannot also rewrite the .receipts sidecar — which sits next to the store, so an attacker with that much file access simply recomputes it and passes. We ship that as a failing negative control, not as prose (test_provenance.py::test_an_attacker_who_rewrites_the_sidecar_too_is_NOT_caught). Pass receipt_key= with the key off the write path, or have anchor() witnessed externally, for the property to mean anything against someone who owns the store. Note too that attribution_matches_receipt is a change detector: a legitimate re-derivation upstream can flip it with no attacker present.

None of the machinery here is new. Binding the actor and attribution into a tamper-evident provenance chain so retroactive relabeling is detectable is Hasan, Sion & Winslett, The Case of the Fake Picasso: Preventing History Forgery with Secure Provenance (USENIX FAST 2009; journal version ACM TOS 5(4), 2009); answering provenance facets from one call is standard in provenance-aware databases (Perm, ProvSQL, ProQL); signed, Merkle-logged lineage for LLM agent memory specifically is MemLineage (arXiv:2605.14421), which inspeximus's lineage auto-stamping already credits. What is ours is the packaging: all of it in one zero-dependency file, on by default, with the limits attached to the answer.

Five rules it won't break (each one cost us to learn)

1. Raw capture is immutable. Consolidation adds links and markers; it never overwrites the source. This is what stops the slow accuracy drift of LLM-rewritten memory.
2. Absolute timestamps at write time. Relative/derived times rot the moment they're consolidated.
3. Value-ranked, type-aware decay. Retention is value × a per-type half-life, not recency or access-frequency alone. A uniform access-reset clock keeps merely-popular memories while a load-bearing-but-cold fact — queried once a month, prevents a destructive action — starves; we measured exactly that failure. The fix is that the half-life is set by kind, not by read count: episodic events fade in days, semantic facts in months, procedural rules barely at all. A cold-but-critical fact survives by being typed semantic/procedural (long half-life × its high value), not by frequent reads; access only resets the clock within a type's window.
4. Value is reported at the cohort level (tag / time-block), never per-memory.
5. Contradictions are flagged, never auto-resolved. Silent rewrites destroy trust in the whole memory.

Provenance — why these rules, with receipts

Why these rules — the measured receipts behind inspeximus's design. Click to expand.

inspeximus's design isn't taste; it's what Agora's lab measured:

• Semantic recall beats keyword recall, and the gap widens with scale — as the store grows to a corpus of several thousand notes, lexical recall@5 decays from 0.94 (small store) to 0.25, while semantic holds at ~0.65 — ≈2.6× at full scale (Agora Lab b4c260); on paraphrase queries semantic recall@5 is 0.86 vs 0.20 lexical (3501f1). The embedder is the real lever at scale; the lexical overlap match is the zero-dependency floor that still runs anywhere on a small store. (Honest footnote: pruning universal-matcher hub notes lifts lexical recall ~20% only when a store is link-spammed, and does not move semantic recall — it's a lexical/hybrid optimisation, not a headline.)
• Value-ranked consolidation — under a keep-budget, ranking what to keep by value beats FIFO/random, and the advantage scales super-linearly as the budget shrinks (≈1.8× at half budget → ≈4× at one-eighth), surviving heavy estimation noise.
• Retention must blend value with recency, not decay on access alone — we simulated a half-life-with-access-reset policy (a popularity signal) against a value-aware blend under a shrinking budget, with value made deliberately anti-correlated with access-frequency for a load-bearing-but-cold subset. At a 30% keep-budget the access-decay policy retained only 2.8% of the high-value/low-frequency memories and 20% of total value, vs 100% and 64% for the blend — about 3× more value kept (the gap persists, ≈2.2× retained value, even at a 7% budget). Pure access-frequency decay starves the rarely-queried-but-critical memories; forgetting must consume an explicit value channel separate from access recency. (Agora Lab 19d802.)
• Supersession needs a deterministic key, not embedding similarity — replicating an external result (MemStrata / Yadav, arXiv 2606.26511) on our own local nomic stack: a cosine-similarity classifier separating a contradicted fact from a rephrased duplicate scores AUROC ~0.61 (near chance) — a contradiction is often more embedding-similar to the original than a true rephrase is. A similarity-based store therefore serves the stale value ~42% of the time; the deterministic (subject, relation, object) supersession key (remember(..., key=...)) drives that to 0% (Agora Lab exp_supersession_replication, severe-test 8/8). This is why supersession is a key, not a threshold.
• No single recall mechanism survives all operating points — only the layered store does — head-to-head on a synthetic evolving + contaminated stream (stable / superseded / poisoned facts, local nomic): a naive cosine top-1 store scores 42% (fine on stable, but blind to supersession — 0/8 on updated facts — and fooled by repeated lies); a recency store 67% (fixes supersession but serves the freshest lie — 0/8 on poison); inspeximus — deterministic supersession key + corroboration gate + value-ranking — is 100%, robust across all three. Each single mechanism wins one regime and loses another (the memory operating-point trap), which is why the durable layer needs all three together (probe inspeximus/probes/operating_point_memory.py).
• Cohort-level value — per-memory outcome attribution is statistically underpowered at n-of-1 (the best proxy reached only ~0.36 power at realistic sample sizes); the cohort is where the signal lives. Hence rule 4.
• Contradiction detection runs in production over the 10,000-note vault; the lesson that it must flag, not auto-edit (rule 5) is why silent rewrites are forbidden.

(Methods + numbers live in the Agora track record: https://dancenitra.github.io/agora/.)

Threat model & layered defense (adversarial memory integrity)

The full adversarial threat model + layered defenses. Click to expand.

An untrusted-ingestion memory store cannot decide whether a written claim is true. inspeximus doesn't try to; it makes the attacker pay, and the honest map of what each layer buys — worked to bedrock across a public practitioner thread with adversarial review — is below. Every claim here has a runnable receipt in inspeximus/probes/; this is textbook mechanism with a receipt, not a new theory.

A defense the attacker can also write is a suggestion, not a defense. Content-declared provenance is theater: Source: X and corroborated by N are strings a writer controls, so default (distinct source strings) corroboration falls to a sybil that mints two labels (~0.9 attack-success across 10 models — memory_defense_layer_probe). Only channels the writer does not control hold — distinct verified keys (strict_corroboration, Ed25519 attest) whose issuance is itself costly/rate-limited (a free-to-mint key is just another string a sybil spends), an earned Beta(good,bad) outcome credit a session can't self-grant, and system write-history. That is Biba integrity (1977) / Cheng-Friedman (2005): no symmetric reputation is sybilproof; the escape is an exogenous, un-writable anchor.

The layers, and the exact residual each leaves:

• Provenance — did the call happen? Bind standing to a runtime signature over the real (tool, result), not the session's log (execution_receipt_gate). Closes fabricated logs iff the executor is a trust domain separate from the session; in-process tools → the key is session-readable → theater.
• Veracity — is a real call's output true? No write-time oracle (a novel fact has no priors; attestation = authorship, not truth). Standing is earned at use time from an observed outcome (veracity_outcome_grounding) — only helps where harm is observable.
• The irreversible tail. A provenance-scaled spend_irreversible budget makes a low-provenance memory bind an honest action's irreversible spend against itself (soft_influence_taint); a reversibility checkpoint bounds a one-shot defector. Bounds, doesn't close (Sybil relocates it per identity).
• The sub-threshold coordinated campaign. A temporal change-detector is evaded for free at bias h→0, but B≈N·h forces a growing correlated low-provenance population a cross-sectional detector catches (two_detector_trap); and randomized retrieval raises a targeted attacker's coverage from O(1) to ~Θ(fN) with no anchor (moving_target_retrieval).

The bedrock. Checked from ~8 directions (detection, reputation, elicitation-without-ground-truth à la Bayesian Truth Serum, robust aggregation, moving-target), every layer we examined reduces to one of two exogenous anchors — a bounded corruption count (Byzantine; sybils break it) or a shared attacker-independent prior (peer-prediction; a coalition coordinating its reports breaks it). (A synthesis over those cases, not a proof.) You cannot separate a large coordinated coalition from genuine consensus from internal signals alone (Cheng-Friedman + Lamport-Shostak-Pease 1982; and no internal truth-oracle, by analogy to Tarski's undefinability). What that leaves is not "give up" but a shape: localize the one exogenous check at the rare high-consequence irreversible step (a human, a separately-provenanced feed — a channel the poison can't reach), and don't let evidence-free consensus drive an irreversible action (weight it ~0; on an observable target, require an independent evidentiary provenance, which is super-linear to forge, not N reputations). The residual is the integrity of that one minimal anchor — a standard, bounded problem, not the intractable verify-all-memory one.

Prior art credited throughout: Biba 1977 · Douceur 2002 · Cheng-Friedman 2005 · Friedman-Resnick 2001 · Lamport-Shostak-Pease 1982 · Lorden 1971 / Moustakides 1986 (CUSUM delay floor) · Tarski (undefinability of truth, used by analogy) · Doyle 1979 (truth-maintenance) · Garcia-Molina & Salem 1987 (Sagas) · Prelec 2004 (Bayesian Truth Serum) · Blanchard 2017 / Yin 2018 (Byzantine-robust aggregation) · PoisonedRAG (Zou 2024) · MINJA (Dong, arXiv:2503.03704) · AgentPoison (Chen, arXiv:2407.12784) · the shilling / Sybil-detection line (Mobasher-Burke 2007, Mehta-Nejdl 2009, SybilRank/Cao 2012, Viswanath 2010).

The second_brain thinking layer

An optional layer on top of the store — dialectic, contradiction surfacing, question generation: docs/SECOND_BRAIN.md.

Status

v0.2 — the core, honest and runnable, now with two MCP servers (mcp for memory, second_brain_mcp for the thinking layer over your notes) and a deterministic supersession key (remember(..., key=...)) that closes the embedding supersession blind spot. Roadmap: pluggable vector stores, a hosted tier. Open-core; the core stays free.

MIT-licensed · part of Agora.

Self-maintaining (maintain.py)

The #1 second-brain frustration is maintenance, not capture. maintain.py runs the chore people stop doing — over a folder of Markdown notes it finds dead [[wikilinks]], orphan notes, stale notes, near-duplicate clusters, and a vault health score (self_legibility = % of notes in the link graph's giant component — knowledge debt is a percolation collapse, so it warns before the cliff). Crucially it turns findings into actions: for each orphan it suggests which existing note to link it to (re-connecting it to the graph), and flags archive candidates (old + isolated). It resolves links by filename or frontmatter alias, and dates notes by frontmatter (not git-reset mtime) — both learned from dogfooding it on a real ~7,700-note vault (it rescued ~300 falsely-flagged orphans). Advisory + safe: it returns a plan and an action list; it never edits, moves, or deletes a note. And it can apply the fix when you ask: apply_suggestions appends a marked ## Related (auto-suggested) block of [[links]] to each orphan — additive only, idempotent (re-running replaces its own block), dry-run by default. python maintain.py runs a verified round-trip on a synthetic vault (diagnose → suggest → apply); maintenance_report and apply_links in second_brain_mcp.py expose it to any MCP agent.

mcp-name: io.github.DanceNitra/inspeximus