What is Predicate?

Most agent "memory" is a flat pile of text: the model re-reads it and takes it on faith — no record of where a fact came from, no guarantee the same question answers the same way twice, and no signal when two notes contradict each other. It never gets smarter; it just gets bigger.

Predicate is different. It stores facts as RDF triples with per-triple provenance and confidence, and answers questions through a deterministic reasoner that produces an explanation path for every derived claim. And it learns its own shape: the schema is versioned like code and evolves under a propose → validate → use-gated promotion loop, so the structure your agent relies on gets sharper the more it's used — and prunes what it doesn't.

The bet is not that a graph recalls facts better than a long context window — at the scales we've measured (predicate-eval/SCALE-FINDINGS.md), in-context recall is competitive and often simpler. The bet is that a graph makes answers auditable, reproducible, and contradiction-aware in a way a flat pile can't.

Why it's different

• Auditable answers. kg_explain returns the chain of triples and rules that produced a claim — each step cited back to its source and confidence. Not "trust me," but "here's the derivation."
• Contradictions surface instead of averaging out. When two sources disagree about a fact the schema marks functional or disjoint, the reasoner flags the conflict rather than silently picking one.
• The graph remembers, and the schema earns its keep. Facts persist across sessions. New schema becomes durable only after real queries reference it within a TTL — unused proposals expire on their own, so the graph can't thrash.
• Goal-conditioned growth. Concepts enter the graph because a goal needed them, not because a document mentioned them.

Install / use it in your agent

Prerequisite: Node 20+. Nothing else — no Docker, no database to run.

The fastest path is the predicate-skill npm package, which bundles the MCP server, the predicate CLI, and per-client integration adapters.

/plugin marketplace add NordicAgents/predicate
/plugin install predicate@predicate

predicate up        # creates the local store + the 8 named graphs
predicate doctor    # all checks green

codex plugin marketplace add NordicAgents/predicate
# then enable "predicate" in the interactive plugin browser

npx predicate-skill install vscode    # writes .vscode/mcp.json + AGENTS.md
npx predicate-skill install cursor    # writes .cursor/mcp.json + AGENTS.md

Manual install (fallback for any host)

If a native plugin/marketplace install fails — or your host isn't listed above (Continue.dev, OpenCode, any stdio MCP client) — run Predicate as a plain stdio MCP server. You get all 10 kg_* reasoning tools on any MCP-capable host; the only thing you lose is automatic Stop-hook capture (and, on Claude Code, the slash commands).

npm install -g predicate-skill   # published package; ships the server + CLI
predicate up                     # create the local store + named graphs
predicate doctor                 # all checks green

# The MCP server command is (copy the resolved absolute path):
node "$(npm root -g)/predicate-skill/server.bundle.mjs"

No env vars are required: the server defaults to the disk-backed Oxigraph store (PREDICATE_BACKEND=oxigraph, PREDICATE_DATASET=predicate) — identical to the native installs. Set them only to override.

Register that command with your host:

Claude Code

claude mcp add predicate -- node "$(npm root -g)/predicate-skill/server.bundle.mjs"

Codex CLI — add to ~/.codex/config.toml (use the absolute path printed by npm root -g):

[mcp_servers.predicate]
command = "node"
args = ["/ABSOLUTE/PATH/predicate-skill/server.bundle.mjs"]

Continue.dev — in ~/.continue/config.yaml:

mcpServers:
  - name: predicate
    command: node
    args: ["/ABSOLUTE/PATH/predicate-skill/server.bundle.mjs"]

Full per-client matrix, the 10 MCP tools, the CLI reference, and config live in the package README: packages/predicate-skill/README.md.

Architecture

%%{init: {
  "theme": "base",
  "themeVariables": {
    "fontSize": "15px",
    "primaryColor": "#FFD23F",
    "primaryTextColor": "#1A1A1A",
    "primaryBorderColor": "#1A1A1A",
    "lineColor": "#1A1A1A",
    "edgeLabelBackground": "#FFF7E1"
  }
}}%%
flowchart LR
  Agent["<b>your agent</b><br/>Claude Code · Codex"]:::actor
  Hook["<b>Stop hook</b><br/>turn capture"]:::actor

  subgraph Predicate["PREDICATE"]
    direction TB
    Tools["<b>10 kg_* tools</b><br/>stdio MCP"]:::iface
    Reasoner["<b>21-rule reasoner</b><br/>16 OWL 2 RL + 5 domain<br/>+ SHACL"]:::compute
    Storage["<b>Storage adapter</b><br/>Oxigraph · Fuseki"]:::data
    Graphs[("<b>8 named graphs</b><br/>tbox · tbox-staging · abox<br/>inferred · provenance · meta<br/>goals · usage")]:::store
  end

  Agent -->|MCP| Tools
  Hook  -->|assert| Tools
  Tools -->|SPARQL| Storage
  Storage <--> Graphs
  Reasoner -.->|CONSTRUCT fixpoint| Graphs
  Tools   -.-> Reasoner

  classDef actor   fill:#FFD23F,stroke:#1A1A1A,stroke-width:3px,color:#1A1A1A
  classDef iface   fill:#4ECDC4,stroke:#1A1A1A,stroke-width:3px,color:#1A1A1A
  classDef compute fill:#FF6B6B,stroke:#1A1A1A,stroke-width:3px,color:#FFFFFF
  classDef data    fill:#1A535C,stroke:#1A1A1A,stroke-width:3px,color:#FFFFFF
  classDef store   fill:#FFFFFF,stroke:#1A1A1A,stroke-width:3px,color:#1A1A1A

  style Predicate fill:#FFF7E1,stroke:#1A1A1A,stroke-width:3px,color:#1A1A1A

The agent reads the schema (kg_explore_schema), drafts SPARQL, asserts facts with provenance (kg_assert), and asks questions (kg_ask). The reasoner does the logic; the model formulates queries and interprets results.

Runtime flow

%%{init: {
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  "themeVariables": {
    "fontSize": "14px",
    "actorBkg": "#FFD23F",
    "actorBorder": "#1A1A1A",
    "actorTextColor": "#1A1A1A",
    "actorLineColor": "#1A1A1A",
    "signalColor": "#1A1A1A",
    "signalTextColor": "#1A1A1A",
    "noteBkgColor": "#FF6B6B",
    "noteTextColor": "#FFFFFF",
    "noteBorderColor": "#1A1A1A",
    "labelBoxBkgColor": "#4ECDC4",
    "labelBoxBorderColor": "#1A1A1A",
    "labelTextColor": "#1A1A1A",
    "sequenceNumberColor": "#FFFFFF",
    "activationBkgColor": "#FFD23F",
    "activationBorderColor": "#1A1A1A"
  }
}}%%
sequenceDiagram
  participant Host as Agent host
  participant Stop as stop.sh hook
  participant Ext as turn-extractor.ts
  participant KG as kg_* tools
  participant R as Reasoner
  participant G as Named graphs

  rect rgb(255, 247, 225)
  Note over Host,G: TURN ENDS — capture
  Host->>Stop: turn payload (stdin)
  Stop->>Ext: predicate extract --from-stdin
  Ext->>KG: kg_assert (typed triples + provenance)
  KG->>G: write kg:abox + kg:provenance
  R->>G: forward-chain to fixpoint → kg:inferred
  end

  rect rgb(230, 250, 248)
  Note over Host,G: NEXT TURN — ask
  Host->>KG: kg_explore_schema / kg_ask
  KG->>G: SPARQL
  G-->>KG: results
  Host->>KG: kg_explain (why?)
  KG-->>Host: derivation path (cited triples + rules)
  end

More diagrams (schema lifecycle, scale findings) live in docs/diagrams/.

How it works

• Storage. 8 named graphs separate slow-changing schema (kg:tbox) from fast-flowing facts (kg:abox), materialized entailments (kg:inferred), per-triple metadata (kg:provenance), goals (kg:goals), usage logs (kg:usage), staging (kg:tbox-staging), and version history (kg:meta).
• Reasoning. A curated set of 21 rules — 16 OWL 2 RL rules plus 5 domain and judgment derivations (Hotspot, FlakyCommand, ActiveFile, current-judgment, conflict detection). The entailment rules run as SPARQL CONSTRUCT forward-chained to a fixpoint; disjointness is checked as an inconsistency pass; SHACL shapes add closed-world validation. The OWL 2 RL coverage is a scoped subset — in v1, owl:propertyChainAxiom is limited to length-2 chains and owl:hasKey to single-property keys.
• Provenance. Every triple is annotated with source, time, confidence, and extraction method using RDF-star. Low-confidence triples stay visible to queries but are excluded from the inference closure, so they cannot poison entailment.
• Schema lifecycle. The agent proposes deltas to kg:tbox-staging, never to kg:tbox directly. A proposal is promoted only after the reasoner accepts it and it has been referenced by N successful queries inside a TTL; unused proposals expire quietly.
• Cross-session continuity. A Stop hook extracts typed triples from each turn — files modified, commands that passed or failed — into kg:abox. The reasoner derives Hotspot, FlakyCommand, and ActiveFile so the next session can ask "what's unstable here?" without re-reading the repo.

Packages

This is a pnpm monorepo. Each package has its own README with details.

Development

git clone https://github.com/NordicAgents/predicate
cd predicate
pnpm install
pnpm build            # builds all packages + the plugin bundle
pnpm test             # runs against the default Oxigraph backend, no Docker needed
                      # for the Fuseki leg: PREDICATE_BACKEND=fuseki + a running Fuseki

Other root scripts: pnpm typecheck, pnpm lint, pnpm fuseki:up, pnpm fuseki:down.

License

Elastic License 2.0 (ELv2) — source-available. See LICENSE.