nous-lang 5.2.0

NOUS (Νοῦς) — The Living Language for Agentic AI Systems

NOUS (Nous) -- The Living Language

The first agentic programming language with end-to-end formal cost-bound verification, in any currency the pricing table declares.

  _   _  ___  _   _ ____
 | \ | |/ _ \| | | / ___|
 |  \| | | | | | | \___ \
 | |\  | |_| | |_| |___) |
 |_| \_|\___/ \___/|____/   v5.0.0

Author: Hlias Staurou (Hlia) | Project: Noosphere | GitHub: contrario/nous | Website: nous-lang.org

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What is NOUS?

NOUS is a programming language for agentic AI systems where every program is:

• Verifiable -- declare a cost_cap in USD or EUR and Z3 proves at compile time that no execution path can ever exceed it.
• Auditable -- every verified program emits an Ed25519-signed manifest with full provenance (source SHA-256, AST SHA-256, pricing SHA-256, SMT obligations SHA-256, solver name+version, verdict, timestamp).
• Annex IV-ready -- nous dossier emits an EU AI Act Annex IV-aligned compliance bundle directly from the AST plus the signed manifest plus the pricing table.
• Governable -- first-class policy { on ... signal ... action ... } declarations, statically lintable (13 rule codes) and live-simulatable.
• Deterministically replayable -- every agent run produces a SHA-256-chained JSONL event log. nous replay verify validates chain integrity offline.
• Self-evolving -- programs can observe their own execution, evaluate fitness, mutate DNA parameters, and self-heal within constitutional safety bounds.

NOUS transpiles to Python 3.11+ asyncio. The toolchain is a single PyPI package -- no Java, no Docker, no LangChain / LlamaIndex / CrewAI dependencies.

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Why v5.0.0 matters

Every other agentic framework lets you set a "max budget" at runtime and abort when it is exceeded -- by which point the spend has already happened. NOUS lets you prove before you ship that every reachable execution stays under the cap. The proof is mechanical (Z3), the cost model is auditable (signed pricing TOML with SHA-256), and the artefact (signed manifest) is verifiable by anyone holding your public key -- making it directly useful for EU AI Act Annex IV / Article 11(1) technical documentation.

v5.0.0 adds end-to-end EUR cost verification. Earlier versions hard-blocked any cap currency other than USD; v5.0.0 lifts that block while preserving the Phase 5a currency-mismatch guard, so a USD pricing table with an EUR cap (or vice versa) is still rejected at compile time. The pricing TOML schema drops its _usd field-name suffix in favour of a per-table _currency declaration; existing v1.0 files load with one DeprecationWarning and migrate cleanly via nous prices upgrade.

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Install

# Core toolchain (cryptography is base, not optional)
pip install nous-lang

# With SMT cost-bound verification (adds Z3)
pip install 'nous-lang[smt]'

# With LSP server (VS Code / editor diagnostics)
pip install 'nous-lang[lsp]'

# Everything
pip install 'nous-lang[all]'

Requirements: Python 3.11+. The [smt] extra pulls z3-solver. cryptography (used for Ed25519 signing) is a base dependency since v4.17.0.

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60-second quick start

# 1. Initialise a project
mkdir my_world && cd my_world
nous prices init                       # writes ./nous_prices.toml from defaults
nous templates extract cost_cap_basic  # copies a working .nous program

# 2. Verify formally
nous verify cost_cap_basic.nous --smt
# -> Verdict: PROVEN. Manifest written to cost_cap_basic.manifest.json.

# 3. Emit an Annex IV compliance dossier
nous dossier cost_cap_basic.nous
# -> bundles source, AST, manifest, pricing table, and Annex IV mapping

For EUR end-to-end verification, point --prices at an EUR pricing table:

nous verify --smt my_eur_agent.nous \
    --prices /path/to/eur_prices.toml

The shipped pricing/eur_example.toml declares four illustrative Mistral models priced in EUR per 1 000 000 tokens. Values are explicitly marked illustrative; verify against the provider before any production use.

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Core CLI

nous run file.nous              # compile + execute
nous compile file.nous          # -> Python file
nous verify file.nous           # governance lint as build gate
nous verify file.nous --smt     # SMT cost proof + signed manifest
nous verify file.nous --smt --smt-margin 10
                                # prove total_cost <= cap * 90/100
nous emit-smt file.nous         # SMT-LIB 2.6 source (re-usable across solvers)
nous dossier file.nous          # EU AI Act Annex IV compliance bundle

nous prices show                # active layered pricing table + SHA-256
nous prices init                # write nous_prices.toml in cwd
nous prices verify <model>      # detailed cost breakdown for one model
nous prices age                 # staleness report across all entries
nous prices upgrade <file>      # migrate v1.0 -> v2.0 schema (preserves comments)

nous governance lint file.nous  # static analysis (13 rule codes)
nous governance simulate ...    # what-if policy evaluation

nous replay verify <log>        # validate JSONL chain integrity
nous replay diff a.jsonl b.jsonl
                                # lockstep event-level diff

nous templates list             # list bundled templates (9 shipped)
nous templates show <name>      # print template source to stdout
nous templates extract <name>   # copy template into a directory
nous lsp                        # start LSP server (stdio)
nous version

The full nous --help lists 48 top-level subcommands; the above covers the most-used surface.

---

Language at a glance

world ExampleWorld {
    cost_cap: 1.00 USD              // formal SMT bound, USD or EUR
    max_ticks: 10                   // bound on heartbeat cycles
    law CostCeiling = $0.10 per cycle
    law MaxLatency = 30s
    law NoLiveTrading = true
}

soul Sentinel {
    mind: claude-opus-4-7 @ Tier1
    tokens: input=1000 output=400   // SMT input
    senses: market_feed, risk_oracle
    speaks: AlertChannel
    remembers: last_signal
}

policy on llm.response signal contains_phrase("absolutely") action log_only weight 0.3

---

Architecture

Layer	Implementation
Grammar	Lark LALR (nous.lark), 115 rules, bilingual EN+GR
AST	Pydantic V2 strict models, 61 node types
Validator	Constitutional law checker on AST
Pricing	Layered TOML (CLI > project > user > package), SHA-256 audit, schema v2.0, currency-agnostic
SMT emit	Deterministic SMT-LIB 2.6, exact rationals (no floats)
SMT solve	Z3 wrapper + counterexample extraction + fix suggestions
Manifests	Ed25519-signed JSON, manifest schema v1.0, offline-verifiable
Dossier	EU AI Act Annex IV-aligned compliance bundle from AST + manifest
CodeGen	AST -> Python 3.11+ asyncio
Replay	SHA-256-chained JSONL event log, integrity-verifiable offline
Runtime	asyncio event loop + Noosphere integration
LSP	stdio JSON-RPC, lint diagnostics with source="nous.lint"

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The signed-manifest contract

When nous verify --smt returns PROVEN, it writes a JSON manifest:

{
  "schema_version": "1.0",
  "nous_version": "5.0.0",
  "smt_emit_version": "...",
  "source_path": "trading.nous",
  "source_sha256": "...",
  "ast_sha256": "...",
  "pricing_sha256": "...",
  "smt_obligations_sha256": "...",
  "solver": "z3",
  "solver_version": "...",
  "verdict": "proven",
  "cost_cap": "0.50",
  "currency": "USD",
  "timestamp": "2026-05-03T19:12:54Z",
  "signature": "<base64 ed25519>",
  "public_key": "<base64 ed25519 pubkey>"
}

Anyone with the manifest and the publisher's public key can re-verify offline. Tamper-detection is built in. The verifier signing key lives at $XDG_DATA_HOME/nous/keys/signing.key (mode 0600, auto-generated; falls back to ~/.local/share/nous/keys/signing.key if XDG is unset; override with --key-path).

---

EU AI Act compliance

NOUS targets EU AI Act conformity for the high-risk AI system requirements of Regulation (EU) 2024/1689. The compliance matrix lives in docs/EU_AI_ACT_COMPLIANCE.md. Current coverage: 8 of 10 mapped articles fully covered, 1 planned, 1 out of scope.

Key article alignments:

• Article 11 (Technical Documentation) -- nous dossier emits an Annex IV-aligned bundle directly from the AST.
• Article 12 (Record-Keeping) -- SHA-256-chained JSONL replay logs, integrity-verifiable via nous replay verify.
• Article 14 (Human Oversight) -- intervene, inject_message, block policy actions plus governance simulator.
• Article 15 (Accuracy / Robustness / Cybersecurity) -- Z3 SMT proofs on every cost_cap declaration, currency-aware (USD + EUR), with Ed25519-signed manifests.
• Article 17 (Quality Management) -- 10-phase release pipeline, 503-test pytest floor, 57-template byte-identical regression harness.

Annex IV dossiers from existing SKILL.md skills (v5.1.0+)

NOUS can produce signed Annex IV dossiers directly from skill folders that follow the agentskills.io SKILL.md spec, without modifying the skill itself. Add a nous.yaml sidecar declaring cost_cap, default_model, and per-tool max_calls / input_tokens / output_tokens, then:

nous dossier-spec ./my-skill/

The resulting bundle contains the verbatim SKILL.md and nous.yaml, a deterministic source envelope (source.nous), the signed manifest.json, the resolved pricing TOML, the public key, a human-readable README, and an offline verify_offline.py. SKILL.md is left byte-identical, so strict spec validators continue to pass. See docs/SKILL_MD_SIDECAR.md for the schema reference and CLI flag documentation. For the inverse direction -- emitting an agentskills.io skill from a .nous program via CLI, HTTP API, or IDE button -- see docs/SKILL_EXPORT.md.

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Documentation

• Cost Verification Guide -- end-to-end walkthrough for USD and EUR
• SMT Verification Design -- soundness contract, Z3 pin rationale
• EU AI Act Compliance -- Annex IV / Article 11 mapping

---

Contributing

NOUS is developed under a non-standard model: single maintainer, chat-driven, idempotent patch scripts, 10-phase release pipeline. External contributions are welcome but follow an "issue first, PR after we agree on shape" intake. See CONTRIBUTING.md and CODE_OF_CONDUCT.md.

Security issues should be reported via GitHub Security Advisories, not public issues.

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Stats (v5.0.0)

Metric	Value
Tests	503 passing (PYTEST_FLOOR enforced)
Regression	57 templates, 0 baseline drift
Shipped templates	9 (templates/*.nous)
Grammar rules	115 (Lark LALR, bilingual EN+GR)
AST node types	61 (Pydantic V2 strict)
Lint rule codes	13 (L000 - L012, L100)
CLI subcommands	48 (nous --help)
Pricing schema	v2.0 (currency-agnostic, per-table _currency)
Manifest schema	v1.0 (Ed25519-signed, offline-verifiable)
New in v5.0.0	EUR end-to-end SMT, nous prices upgrade, sha-stable v1->v2 migration

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License

MIT. See LICENSE.

Changelog

See CHANGELOG.md. Latest release: v5.0.0 (3 May 2026).