B3 — Local Code Intelligence (Concise)

B3 is a local-first, offline-first, free-by-default code intelligence platform for MCP-compatible coding agents and local developer workflows. PLAN.md is the source of truth for the full roadmap and detailed phase notes.

Quick links:

• Roadmap (source of truth): PLAN.md
• Dev docs: DEVELOPMENT.md
• MCP tools: MCP_TOOLS.md

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What B3 Is

• A Rust-native indexer that builds a local SQLite-backed code graph (.b3/b3.db).
• A thin MCP runtime exposing a curated toolset for agent integrations.
• A localhost control server and a local Next.js web UI for inspection and manual workflows.
• Scoped indexing and conservative, explainable static intelligence for supported stacks.

Current Status

Completed:

• Phase 9.2.12 — .NET Desktop / WPF Intelligence
• Phase 10.0 — Local Embeddings + Vector Search Architecture
• Phase 10.1 — Local Embedding Provider MVP
• Phase 10.2 — SQLite Vector Storage / Search Index
• Phase 10.3 - Hybrid Search Ranking
• Phase 10.4 - MCP / Control API Integration
• Phase 10.5 - Benchmark + Quality Evaluation
• Phase 11.0 - Cross-Project Architecture Model + Contracts
• Phase 11.1 - Group Query Federation
• Phase 11.1.1 - Context Efficiency + Tool Call Reduction Benchmark
• Phase 11.2 - Cross-Repo Route / API Matching
• Phase 11.3 - Cross-Repo Messaging Matching
• Phase 11.4 - Cross-Repo Package / Contract / Infra Matching

Current / Next:

• Phase 11.5 - Group-Level Impact + Context Pack

Upcoming (major):

• Phase 11.6 - Architecture Graph / Service Map API
• Phase 11.7 - Cross-Project Benchmark + Docs
• Phase 12 — Symbolic Editing MVP
• Phase 13 — Rename / Refactor MVP

See PLAN.md for the full, authoritative roadmap and phase details.

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What Works Today

Core platform:

• Repository indexing into .b3/b3.db (local project model).
• MCP runtime (stdio) with curated tool profiles.
• Local control server (http://127.0.0.1:7777) and local web UI (http://127.0.0.1:8888).
• Scoped indexing (path/file/glob/language/framework).
• Local registry and metadata-first project groups (local JSON registry).

Language and framework intelligence (basic/static/local):

• Rust (best support)
• JavaScript / TypeScript / JSX / TSX
• Node.js REST (Express / NestJS / Fastify)
• React / Next.js / Angular (static extraction)
• ASP.NET Core / C# Web API
• Go (basic static support)

Application intelligence (static hints):

• ORM / data-access (EF Core, Dapper, Prisma, TypeORM, Sequelize)
• Realtime / Socket (WebSocket, Socket.IO, SignalR)
• Messaging/event-driven (AMQP/RabbitMQ, Kafka, Google Pub/Sub)
• Cloud / infrastructure hints (Docker, Compose, Kubernetes, Terraform)
• C# WPF / XAML (basic static/local)

Vector foundation:

• local_hash embeddings and SQLite vector persistence/search (local/offline raw vector search).
• Hybrid ranking combines lexical, vector, and metadata signals inside b3-query.
• Local hybrid search is exposed through POST /api/search/hybrid and the MCP semantic_search tool.
• Fixture-based benchmark/quality evaluation is available through cargo run -p b3-bench -- baseline.
• The default local benchmark config path is benchmarks/b3.benchmark.toml; its real-local repository paths are optional candidates and missing paths are warnings, not build/test failures.
• Phase 11.1.1 adds a local context-efficiency benchmark comparing deterministic file-by-file exploration, search_code, semantic_search, context-pack-style selection, and a group-summary model.
• Production-grade neural embedding providers are planned in later optional-provider phases.

Cross-project architecture foundation:

• Phase 11.0 adds serializable local architecture contracts for projects, groups, services, nodes, edges, match candidates, confidence, provenance, and normalization.
• Phase 11.1 resolves local registry groups and federates read-only summaries across repo-local .b3/b3.db files.
• Phase 11.1.1 measures token/context reduction, tool-call reduction, and fixture-based answer-quality approximation. Current measured balanced context-pack baseline is about 1.11x fewer tokens, 4.05x fewer modeled tool calls, and 0.699 answer-quality score; the 10x token target and 0.8 quality target are not met yet.
• Phase 11.2 adds local/read-only cross-repo route/API matching inside registry project groups.
• Phase 11.3 adds local/read-only cross-repo messaging matching inside registry project groups.
• Phase 11.4 adds local/read-only cross-repo package, contract, and infrastructure matching inside registry project groups.
• B3 still preserves 1 project = 1 repo-local .b3/b3.db; group impact/context packs and service maps are deferred to later Phase 11 subphases.

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Current Limitations

• Support for non-Rust stacks is mostly conservative/static/local, not full semantic analysis.
• local_hash embeddings are lexical/hash-based, not neural semantic-quality vectors.
• MCP/control semantic search is local/offline and uses lexical/hash-based local_hash, not neural semantic vectors.
• Quality metrics are fixture baselines, not production guarantees.
• Efficiency metrics are deterministic benchmark estimates. Token estimates use chars/4, tool-call counts use a fixed local workflow model, and answer quality is fixture coverage rather than human grading.
• Cross-project route/API matching is static and conservative. It does not execute HTTP requests, fetch OpenAPI remotely, infer messaging/package/infra relationships, or build service maps.
• Cross-project messaging matching is static and conservative. It does not connect to brokers, publish/consume messages, call cloud Pub/Sub APIs, infer package/contract/infra relationships, or build service maps.
• Cross-project package/contract/infra matching is static and conservative. It does not run package managers, Docker, Kubernetes, Terraform, cloud CLIs, remote schema fetches, or schema compatibility validation.
• Symbolic editing / rename & refactor: Phase 12 / Phase 13.
• B3 does not execute code or run cloud/broker/database/package-manager commands by default.

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When Can We Use It? (short table)

Use case	Status
MCP runtime (Codex/Cursor)	Usable now
Local repository indexing (.b3/b3.db)	Usable now
Project init / index / reindex	Usable now
MCP tool profiles	Usable now
Multi-project local workflow / groups	Usable now, metadata-only
JS/TS / JSX / TSX indexing	Usable now, basic/static
Node.js REST route intelligence	Usable now, basic/static
React / Next.js / Angular	Usable now, basic/static
C# Web API / ASP.NET Core	Usable now, basic/static
ORM / data-access hints	Usable now, basic/static
Realtime / Socket hints	Usable now, basic/static
Messaging (Kafka/RabbitMQ)	Usable now, basic/static
Docker / Compose / Kubernetes / Terraform	Usable now, basic/static
SignalR	Usable now, basic/static
Scoped indexing targets	Usable now
C# WPF / XAML	Usable now, basic/static/local
Local embeddings & SQLite vector search	Usable now, local/offline raw vector search
Hybrid semantic ranking	Usable now, local/offline
MCP semantic search tool	Usable now, local/offline
Search quality benchmark	Usable now, local fixture baseline
Context efficiency benchmark	Usable now, local deterministic baseline
Cross-project architecture contracts	Usable now, model/status only
Cross-project group federation	Usable now, read-only summaries
Cross-project route/API matching	Usable now, local/static/read-only
Cross-project messaging matching	Usable now, local/static/read-only
Cross-project package/contract/infra matching	Usable now, local/static/read-only
Refactor assistant / rename & refactor	Phase 12 / Phase 13

Refer to PLAN.md for complete phase definitions and caveats.

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Quick Start (keeps core commands)

Run checks and tests:

cargo fmt --check
cargo check --workspace
cargo test --workspace

Initialize and index a repository (example):

cargo run -p b3-control --bin b3-control-server -- init --project "." --database ".b3/b3.db"
cargo run -p b3-control --bin b3-control-server -- index --project "." --database ".b3/b3.db"

Run the control server:

cargo run -p b3-control --bin b3-control-server -- serve --project "." --database ".b3/b3.db" --port 7777

Run the MCP runtime:

cargo run -p b3-mcp-runtime -- serve --project "." --database ".b3/b3.db"

Start the web UI (local):

cd apps/web-ui
npm install
npm run dev
# web UI: http://127.0.0.1:8888

Project Model (ASCII)

Business Application ├── Backend API ├── Frontend App ├── Worker Service ├── Desktop Client └── Runtime Infrastructure

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Offline / Free Guarantee

B3 remains offline-first and free-by-default. Core features do not require any external APIs, cloud services, hosted vector DBs, OpenAI/cloud embedding APIs, telemetry, or internet access. Optional external or paid integrations are explicit plugins disabled by default.

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For detailed roadmap, phase status, and implementation notes see PLAN.md.