nexu 0.5.12

Visual Intent Contract Orchestrator: freeze project slices, evolve capsules, verify intent contracts.

Nexu

AI Cost Tracking

• 🤖 LLM usage: $2.1564 (18 commits)
• 👤 Human dev: ~$818 (8.2h @ $100/h, 30min dedup)

Generated on 2026-05-31 using openrouter/qwen/qwen3-coder-next

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Nexu — Visual Intent Contract Orchestrator.

Nexu is a Python package and CLI for creating small, isolated project capsules from a large codebase. It helps you freeze a baseline, extract a slice of code/data/contracts, evolve that slice through multiple LLM or human iterations, and verify the result against formal intent contracts before promoting it back.

The core workflow is:

freeze → capsule create → plan → blueprint → iterate → runtime → export-prompt → verify → report → promote

Nexu is designed to work with Intract-style intent contracts, but it can run as a standalone prototype. The goal is not to make an LLM magically correct. The goal is to keep the LLM inside a small, versioned, contract-bound sandbox and detect when its output diverges from declared intent.

What changed in 0.5.0

The fifth iteration adds LLM orchestration and an MCP service:

• capsule orchestrate creates an offline or optional LLM-assisted step-by-step capsule evolution plan,
• orchestration writes orchestration.yaml, orchestration.md, orchestration-prompt.md and context YAML,
• nexu mcp tools lists tools available to IDE/agent clients,
• nexu mcp serve exposes Nexu operations through a conservative MCP-compatible stdio JSON-RPC service,
• MCP promotion remains dry-run only and LLM network calls remain disabled unless explicitly allowed in nexu.yaml.

Why Nexu?

Long-running IDE prompting has a common failure mode:

large repo + vague task + many steps = context drift and hallucinated implementation

Nexu changes the operating model:

large repo
  ↓ freeze baseline
small capsule
  ↓ evolve only this capsule
verified result
  ↓ promote to the real project

Install locally

python -m venv .venv
. .venv/bin/activate
pip install -e .[dev]
nexu --help

First run

nexu init .
nexu freeze . --name baseline
nexu capsule create . --name menu-icons --domain menu --include "examples/frontend_view/src/**" --route /menu-icons
nexu capsule plan menu-icons --steps 10 --goal "Add preview, confidence and reason fields"
nexu capsule blueprint menu-icons --print
nexu capsule iterate menu-icons --steps 3 --goal "Add preview, confidence and reason fields"
nexu capsule runtime menu-icons
nexu capsule orchestrate menu-icons --steps 10 --goal "Add preview, confidence and reason fields"
nexu capsule export-prompt menu-icons
nexu capsule verify menu-icons
nexu capsule review menu-icons
nexu capsule report menu-icons
nexu capsule bundle menu-icons
nexu capsule diff menu-icons
nexu capsule drift menu-icons
nexu capsule promote menu-icons --dry-run

Key Features Added Recently

• Secure Workspace Promotion: Support for applying capsule changes to the source workspace via the nexu capsule promote --apply command (and via the nexu_capsule_promote_apply MCP tool).
• Dynamic Intract Policy Engine Integration: Runs the actual sibling intract package validations (including AST verification and contract compliance) during the capsule verify step to guarantee correctness.
• Web App Dashboard Evolution Example: Fully details multi-stage sandbox visualization and evolution under examples/web_app_dashboard.
• Web App Calculator Mock Example: Compares a simple arithmetic layout (S0) and a scientific layout (S2) under examples/web_app_calculator (evolving the calc capsule).
• Web App Database Analytics Example: Showcases transition from raw SQL/NoSQL table logs to glassmorphic visual charts under examples/web_app_analytics.

Important folders

src/nexu/       Python package
docs/           documentation
examples/       runnable example projects
tests/          unit tests

Documentation

Start here:

• Docs index
• New Project Web Integration Guide
• Calculator UI & Shell Evolution Guide
• Database Analytics Dashboard Evolution Guide
• OpenRouter Real-Time Integration Guide
• Getting started
• Architecture
• Commands
• Capsule format
• Intent contracts
• Verification model
• LLM review and handoff
• LLM orchestration
• MCP service
• Examples
• Roadmap

Main commands

nexu init .
nexu freeze . --name baseline
nexu capsule create . --name my-slice --include "src/my_module/**"
nexu capsule list
nexu capsule status my-slice
nexu capsule blueprint my-slice
nexu capsule iterate my-slice --steps 10 --goal "Evolve final screen"
nexu capsule orchestrate my-slice --steps 10 --goal "Evolve final screen"
nexu capsule export-prompt my-slice
nexu capsule diff my-slice
nexu capsule review my-slice
nexu capsule bundle my-slice
nexu capsule drift my-slice
nexu capsule verify my-slice
nexu capsule review my-slice
nexu capsule bundle my-slice
nexu capsule promote my-slice --dry-run
nexu mcp tools
nexu mcp serve --path .

Cinema (LLM live mode)

To run Cinema with real LLM evolution:

1. Add API key to .env in repo root:

OPENROUTER_API_KEY=...

1. Enable network calls in workspace config (examples/web_app_calculator/workspace/nexu.yaml):

llm:
  allow_network_calls: true
  api_key_env: OPENROUTER_API_KEY

1. Run Cinema iteration:

make cinema

Use the URL printed in the log (Live HTTP Server started for Cinema Player: http://127.0.0.1:…) — not a fixed port (8080 may be taken by another service).

Stop stale cinema servers before restarting:

make cinema-stop
make cinema

Useful helpers:

make cinema-open      # run and open current player URL
make cinema-repair    # re-inject runtime scripts into generated HTML files
NEXU_CINEMA_NO_OPEN=1 make cinema

Simple iteration flow (3 steps):

1. Goal — type what you want (e.g. chemical calculator) → Add goal → Generate Options A–C.
2. Compare — review Options A, B, C (workspace on the left stays unchanged).
3. Promote & refine — click an option to save it to the workspace → drag on buttons (left = keep, right = remove) → Apply marks to workspace.

History & policy (bottom row, two columns): left — Change history with Restore UI + policy (rewinds HTML, ledger, and merges contracts into manifests); right — Policy contracts (baseline + active ledger lines, manifest actions). Use the URL from make cinema output, not a fixed port.

1. Run tests:

make test
make ci-cinema-smoke   # nexu + sibling intract + cinema policy dry-run

You can override defaults from Makefile inline:

make cinema CINEMA_CAPSULE=scientific_calc CINEMA_PATH=examples/web_app_calculator/workspace

Model override (otherwise LLM_MODEL from workspace .env):

make cinema CINEMA_MODEL=openrouter/google/gemini-3.1-flash-lite-preview

License

Licensed under Apache-2.0.