LeX

LeX is subject-neutral infrastructure that turns uncertain judgments into inspectable, reproducible records.

evidence != judgment
judgment != authority
authority != execution
execution != verified success

LeX is a typed-decision switch. An agent sends its own State and QuestionSet; LeX runs them through a pinned typed-decision adapter, checks the raw answers structurally, and returns a sealed, replayable DecisionSet. LeX does not interpret the answers. The agent decides what happens next: ask again, fetch context, call a tool, escalate, or stop.

Jev is the reference decision model, reachable through the direct TypeSafe System One API and through OpenRouter. Providers are adapters, not protocol identities.

Status

Release: canary, envelope 0.2. Fields, meanings, reason codes, and status mapping are fixed within the envelope and change only additively (governance). The revision-pinned canary and its rollback point are in the conformance report. Stable follows after several products use LeX and the gates in progress.md close.

Running profile: Go REST service on Framework v0.3.0 and Context v0.1.0 (embedded runtime memory-exact-v1), deployed on Vercel, request RAM only; no database, disk, queue, server history, or side-effect execution.

How it works

agent: project_id + decision + state + question_set + optional frozen context
  -> LeX: schema, canonical hashes, exact model pin, optional Context rebuild
  -> adapter (Jev): raw typed answers
  -> LeX: structural verification
  -> LeX: DecisionSet + structural report + trace + replay bundle
  -> agent: interpret and choose the next step

Questions are typed:

• Noul: one independent yes/no predicate; the answer is a probability of yes.
• Choice: one mutually exclusive selection among named options.
• Score: a position along ordered levels, in [0, len(levels) - 1].

Keep one atomic claim per question, add other to open taxonomies, and add a non-action option such as manual_review to risky choices. Probabilities are uncalibrated and never grant authority.

HTTP

POST /v1/decisions      State + QuestionSet -> DecisionSet + replay bundle
POST /v1/replays        recheck a returned bundle without calling a provider
GET  /v1/capabilities   primitives, limits, adapter contract, model policy
GET  /healthz

{
  "project_id": "example-project",
  "decision": {"id": "intent-step", "version": "1"},
  "state": {"message": "I need a site to show recent client work."},
  "question_set": {
    "id": "example.intent",
    "version": "1",
    "questions": {
      "intent": {
        "type": "choice",
        "instructions": "Which declared intent best matches the supplied state?",
        "options": {"portfolio": "Show a body of work.", "other": "None of these."}
      },
      "has_purchase_flow": {"type": "noul", "instructions": "Does the supplied state require a purchase flow?"}
    }
  }
}

A valid decision is HTTP 200 with structural_status: "valid". Post the replay_bundle unchanged to /v1/replays. Request errors never reach a provider: non-JSON is 400 invalid_json; a schema or QuestionSet violation is 422 question_error with the failing JSON pointer. Structurally invalid provider answers are 422 decision_error and still return the sealed bundle. Full mapping: checks.md. Examples: .project/examples/.

The wire profile is JSON Schema 2020-12, RFC 8785 JCS with SHA-256, and RFC 9457 problems; schemas and OpenAPI 3.1.1 live in internal/wire/schema/.

Using LeX from another application

1. Get a bearer token bound to your project_id from the operator.
2. Call https://lexproto.vercel.app (or your deployment) from server-side code only; CORS is refused.
3. Keep every replay_bundle you may need to prove later; LeX stores nothing.

client-integration.md has curl, TypeScript, Python, and Go clients. For agents, copy .cursor/skills/lex-api/ into the application's .cursor/skills/.

Running locally

export LEX_BEARER_TOKENS='{"development-token":["example-project"]}'
export LEX_TYPESAFE_API_KEY='replace-with-secret'
go run ./cmd/api

The hosted adapter uses LEX_OPENROUTER_API_KEY and requires LEX_HOSTED_RESOLVED_MODEL, an exact immutable model identity; aliases are refused. Set LEX_DECISION_ADAPTER to direct or hosted when both keys are present. Secrets never go into source, requests, traces, bundles, or logs.

Call a deployment with the token from .env without printing it:

node scripts/lex-request.mjs v1/capabilities
node scripts/lex-request.mjs v1/decisions POST .project/examples/intent-decision-request.json
LEX_REVISION=<sha> LEX_DEPLOYMENT_ID=<id> node scripts/probe-canary.mjs

Checks

python -m pip install -r scripts/requirements-conformance.txt
go test ./... -count=1
go vet ./...
npm run check:english

These enforce the schemas, OpenAPI, and the mapping from every MUST line to a test. They are not a conformance certification.

Documentation

• Specification: concept, protocol, checks, scope, client guide, governance.
• Plan: architecture, decisions, progress, conformance report.
• Jev research (non-normative).

License

Licensed under the Apache License 2.0.