dent8

A memory firewall for coding agents. dent8 sits between your agent and its long-term memory and refuses the writes that quietly corrupt it — a low-authority source overwriting a trusted fact, a stale value resurrecting itself, a poisoned source tainting everything derived from it. Every fact it keeps carries where it came from, and you can replay exactly why the agent believes it.

Most agent memory is newest-write-wins: the last thing written becomes the truth. That's how a scraped web page silently overwrites a decision your team made, and how a retracted source leaves its conclusions behind. dent8 treats memory as an append-only log of fact events — each carrying provenance, authority, and evidence — and arbitrates every write against what is already believed.

The 30-second proof

cargo install dent8
dent8 eval

dent8 eval runs an adversarial corpus against the real firewall and a recency-only baseline (newest-write-wins — the resolution Zep/Graphiti use):

Five for five. The last one is the tell: retract a poisoned source and dent8 flags every fact derived from it — a dependency cascade a recency-only store structurally cannot express.

Try it

dent8 init --identity --source source:alice # local setup: env + authority + signed identity
set -a; . .dent8/env; set +a
. .dent8/identity-alice.env
dent8 authority add web:scrape low       # let this source write at Low, so the next rejection
                                         # is about arbitration, not a missing grant

# A trusted fact goes in.
dent8 assert repo:myproj deploy_target production

# A low-authority source tries to overwrite it — the firewall rejects it: Low can't override High.
dent8 supersede repo:myproj deploy_target staging --authority low --source web:scrape

# It is still production, and here is the receipt that proves why.
dent8 explain repo:myproj deploy_target

# Derive a fact from it, then retract the source — the derivative is flagged tainted.
dent8 derive service:api target production --basis repo:myproj deploy_target
dent8 retract repo:myproj deploy_target
dent8 verify

No services required — dent8 uses a local file log by default. From a clone, watch the whole firewall path run through the real CLI: DENT8="cargo run -q -p dent8 --" ./examples/firewall/demo.sh.

How it works

The primitive is a fact event, not a generic memory item. Every write that enters dent8 is arbitrated at the append boundary (EventStore::append) before it is persisted:

• Authority-weighted arbitration — a write cannot override a fact of higher authority, and dent8 checks the actual authority behind a revision, not just the authority claimed by the event, so laundering a weak fact through a high-authority-looking event is caught.
• Paraconsistent contradiction — disagreement is kept as a contested pair rather than silently resolved; but contradicting a canonical fact is a hard alarm, not a soft contest.
• Earned entrenchment — a fact backed by more independent sources, or one that has survived challenges (rejected attacks are recorded on the fact itself), becomes harder to displace.
• Freshness & valid-time — facts carry TTLs and asserted validity windows; reads flag stale and not-yet-valid facts, and can time-travel ("what did we believe last Tuesday, and was it fresh then?").
• Tamper-evidence — a SHA-256 hash chain over the log, plus an optional off-host witness (Ed25519 signed tree heads) that catches a history rewrite an internal re-check cannot.
• Signed identity — optional issuer-signed grants bind a source to a key; every accepted write carries a signature verify re-checks offline, backed by a hash-chained grant history with first-class revocation.

Nothing is a black box: dent8 replay shows the full event history behind any fact, and dent8 verify re-checks integrity, supersession lineage, and retraction taint.

Use it with your agent

dent8 speaks MCP, so agents read and write memory through the firewall:

dent8 init --agent codex --install-mcp     # signed identity + MCP config for Codex
dent8 doctor --agent codex --write-check   # smoke the installed server + prove the firewall path

Shortcuts exist for codex, claude-code, cursor, gemini, grok-build, cascade, and hecate, and several agents can share one belief base over a common backend. See examples/mcp/ and the per-agent example directories, or wire dent8 in over MCP from LangChain / the Vercel AI SDK.

Share one belief base over a daemon

Instead of one dent8 process per agent, run a per-user daemon and point writes at it:

dent8 mcp serve --daemon                 # Unix socket at $XDG_RUNTIME_DIR/dent8/dent8.sock
export DENT8_DAEMON_SOCKET="$XDG_RUNTIME_DIR/dent8/dent8.sock"
dent8 doctor                             # check the daemon is reachable and you authenticate
dent8 assert repo:app deploy_target production

Every connection proves the daemon-configured source identity with a signed session challenge, and the daemon arbitrates and attests each write as that source — so a daemon-written fact re-verifies offline exactly like a local one, and many processes build one firewalled belief base over one transport. Reads stay local. Run the whole path with DENT8="cargo run -q -p dent8 --" ./examples/daemon/demo.sh (see examples/daemon/). Today the daemon is single-source (it attests with its own key), so this shares one identity across processes; separate agent identities should use separate MCP subprocesses against the same backend, and distinct per-agent identities over one daemon are future work.

Status

dent8 is pre-1.0 and experimental — the CLI, the library API, the on-disk event format, and the Postgres storage schema may all still change between minor versions. The event format is versioned by CANON_VERSION, mixed into every hash so encodings can never collide. v0.3 introduces format v2 (the fact vocabulary — claim_id → fact_id, lowercase authority); this is a deliberate one-time pre-1.0 break, so a v1 log does not carry forward and must be re-ingested from source. From v2 onward the intent is again additive-only (new fields stay optional and out of the hash), but that stability is not guaranteed until 1.0. docs/STATUS.md is the single source of truth for what is runnable vs. library-only vs. design-only. In brief, runnable today:

• The full belief lifecycle — assert / supersede / retract / contradict / reinforce / expire / derive / explain / replay — plus the operator surfaces facts list, verify, conflicts, eval, and export.
• Three backends behind one contract: a local file dev log (default), embedded SQLite, and a DB-verified transactional Postgres adapter (--features postgres) — selected by DENT8_STORE_URL.
• Signed identity with grant history + revocation, the witness transparency log, and an MCP server (dent8 mcp serve) — all in the stock binary.
• Machine-readable --output json across the read/write/audit surface, shell completions, and Parquet export for offline DuckDB analysis (--features export).

Run dent8 --help for the full command surface. The stock binary needs no services; opt-in builds add a Postgres backend (--features postgres) and Parquet export (--features export).

(Origin: the dentate gyrus*, the hippocampal structure associated with pattern separation — keeping similar memories distinct.)*

Documentation

Start here

• Implementation Status — single source of truth for what is built
• Configuration — every env var and Cargo feature
• Changelog

Design

• Project Brief · Architecture · Domain Model
• Belief Revision — dent8's formal identity (the lead lens)
• Storage & the Event Log · Interfaces · Naming
• Decision Records

Correctness & security

• Threat Model — exactly what the firewall does and does not defend
• Formal Verification · Evaluation Strategy

Planning & research

• Roadmap · Release Checklist · Related Work
• Research Dossier · Open Directions · Paper Outline

Development

cargo fmt --all --check
cargo clippy --workspace --all-targets -- -D warnings
cargo test --workspace
DENT8="cargo run -q -p dent8 --" ./examples/firewall/demo.sh

# The Postgres adapter's integration tests are gated on DATABASE_URL (they skip without one):
docker compose up -d
DATABASE_URL=postgres://postgres:dent8@localhost:5432/dent8 \
  cargo test -p dent8-store-postgres --features adapter
docker compose down

CI (.github/workflows/ci.yml) runs the fmt/clippy/test gate across feature combinations and the adapter against a live Postgres service. Security reports: see SECURITY.md.

License

Licensed under either of Apache-2.0 or MIT at your option. Unless you state otherwise, any contribution you intentionally submit for inclusion in the work, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms.