ARC 1

ARC-1 (pronounced arc one [ɑːrk wʌn]) — Enterprise-ready MCP server for SAP ABAP systems. Secure by default, deployable to BTP or on-premise, and hardened with large unit/integration/E2E test coverage.

ARC-1 connects AI assistants (Claude, GitHub Copilot, Copilot Studio, and any MCP client) to SAP systems via the ADT REST API. It ships as an npm package and Docker image.

Full Documentation | Quickstart | Tool Reference

Why ARC-1?

Built for organizations that need AI-assisted SAP development with guardrails. Inspired by the pioneering work of abap-adt-api, mcp-abap-adt, and vibing-steampunk — ARC-1 adds what's needed to run in production:

Security & Admin Controls

• Safe by default — read-only, no free SQL, no table preview, no transport writes, no Git writes. Enable each capability with explicit SAP_ALLOW_* flags
• Action deny list — block specific tool actions with SAP_DENY_ACTIONS (for example SAPWrite.delete), without exposing low-level operation codes to admins
• Package restrictions — limit AI write operations (create, update, delete) to specific packages with wildcards (--allowed-packages "Z*,$TMP"). Read operations are not restricted by package — use SAP's native authorization for read-level access control
• Data access control — enable table data preview (--allow-data-preview=true) or free-form SQL (--allow-free-sql=true) only when needed
• Transport safety — transport reads are available for review, while transport mutations require both --allow-writes and --allow-transport-writes. Update/delete operations auto-use the lock correction number when no explicit transport is provided
• Git workflow safety — Git operations are disabled by default. Enable explicitly with --allow-git-writes / SAP_ALLOW_GIT_WRITES=true
• API-key profiles — multi-key HTTP deployments can assign viewer, viewer-data, viewer-sql, developer, developer-data, developer-sql, or admin per key
• Writes restricted to $TMP when enabled — only local/throwaway objects; writing to transportable packages requires explicit --allowed-packages

Authentication

• API key — simple Bearer token for internal deployments
• OIDC / JWT — Entra ID, Keycloak, or any OpenID Connect provider
• OAuth 2.0 — browser-based login for BTP ABAP Environment
• XSUAA — SAP BTP native auth with automatic token proxy for MCP clients
• Principal Propagation — per-user identity forwarded through Cloud Connector (every SAP action runs as the actual user, not a technical account)

BTP Cloud Foundry Deployment

Deploy ARC-1 as a Cloud Foundry app on SAP BTP with full platform integration:

• Destination Service — connect to SAP systems via managed destinations
• Cloud Connector — reach on-premise systems through the connectivity proxy
• Principal Propagation — user identity forwarded end-to-end via X.509 certificates
• XSUAA OAuth proxy — MCP clients authenticate via standard OAuth, ARC-1 handles the BTP token exchange
• Audit logging — structured events to stderr, file, or BTP Audit Log Service

Token Efficiency

• 12 intent-based tools (~5K schema tokens) instead of 200+ individual tools — keeps the LLM's context window small
• Method-level read/edit — read or update a single class method, not the whole source (up to 20x fewer tokens)
• Context compression — SAPContext returns public API contracts of all dependencies in one call (7-30x compression)

Built-in Object Caching

• Automatic source caching — every SAP object read is cached in memory (stdio) or SQLite (http-streamable). Repeated reads return instantly without calling SAP.
• Dependency graph caching — SAPContext dep resolution keyed by source hash; unchanged objects skip all ADT calls on subsequent runs.
• Pre-warmer — start with ARC1_CACHE_WARMUP=true to pre-index all custom objects at startup, enabling reverse dependency lookup (SAPContext(action="usages")) and fast CDS impact workflows (SAPContext(action="impact", type="DDLS")).
• Write invalidation — when SAPWrite modifies an object, its cache entry is automatically dropped; next read fetches fresh source.

See docs/caching.md for full documentation.

Testing

• 1,367+ unit tests (53 unit test files, mocked HTTP)
• ~160 integration tests against live SAP systems, with explicit skip reasons when credentials or fixtures are missing
• ~70 E2E tests that execute real MCP tool calls against a running ARC-1 server and live SAP system
• CRUD lifecycle and BTP smoke lanes included (test:integration:crud, test:integration:btp:smoke)
• CI matrix on Node 22 and 24; integration + E2E run on push to main and internal PRs
• Reliability telemetry + coverage published as informational CI signals (non-blocking)

Tools Refined for Real-World Usage

The 12 tools are designed from real LLM interaction feedback:

Tool	What it does
SAPRead	Read ABAP source, table data, CDS views, metadata extensions (DDLX), service bindings (SRVB), message classes, BOR objects, deployed UI5/Fiori apps (BSP, BSP_DEPLOY), plus on-prem metadata reads for authorization fields (AUTH), feature toggles (FTG2), and enhancement implementations (ENHO). Structured format for classes returns metadata + decomposed includes as JSON
SAPSearch	Object search + full-text source code search across the system
SAPWrite	Create/update/delete ABAP source and DDIC metadata with automatic lock/unlock (PROG, CLAS, INTF, FUNC, INCL, DDLS, DDLX, BDEF, SRVD, DOMA, DTEL). Batch creation for multi-object workflows (e.g., RAP stack or domain+data element in one call)
SAPActivate	Activate ABAP objects — single or batch (essential for RAP stacks). Publish/unpublish OData service bindings (SRVB)
SAPNavigate	Go-to-definition, find references, code completion
SAPQuery	Execute ABAP SQL with table-not-found suggestions
SAPTransport	CTS transport management (list/create/release/delete/reassign), transport requirement checks, and reverse lookup history (action="history")
SAPGit	Git-based ABAP workflows across gCTS and abapGit (list/clone/pull/push/commit/branch/unlink) with backend auto-selection and safety gating (--allow-git-writes)
SAPContext	Compressed dependency context (action="deps"), reverse dependency lookup (action="usages"), and CDS upstream/downstream impact analysis (action="impact" for DDLS)
SAPLint	Local ABAP lint (system-aware presets, auto-fix, pre-write validation) + ADT PrettyPrint (server-side formatting)
SAPDiagnose	Syntax check, ABAP Unit tests, ATC code quality, short dumps, profiler traces
SAPManage	Feature probing — detect what the system supports before acting

Tool definitions automatically adapt to the target system (BTP vs on-premise), removing unavailable types and adjusting descriptions so the LLM never attempts unsupported operations.

Feature Detection

ARC-1 probes the SAP system at startup and adapts its behavior:

• Detects HANA, gCTS, abapGit, RAP/CDS, AMDP, UI5, and transport availability
• Auto-detects BTP vs on-premise systems
• Maps SAP_BASIS release to the correct ABAP language version
• Each feature can be forced on/off or left on auto-detect
• In shared-credential mode (technical user), runs a startup auth preflight once and blocks SAP tool calls with a clear error on 401/403 to avoid repeated failed logins and potential user lockout

Quick Start

npx arc-1@latest --url https://your-sap-host:44300 --user YOUR_USER

• Trying it out on your laptop? → Quickstart
• Full local dev setup (Docker, cookie extractor, client configs)? → Local Development
• Deploying for a team / BTP? → Deployment

Documentation

Full documentation is available at marianfoo.github.io/arc-1.

Guide	Description
Quickstart	5-minute npx + Claude Desktop setup
Local Development	Full local dev — all install methods, MCP client configs, SSO cookie extractor
Deployment	Multi-user deployment — Docker, BTP Cloud Foundry, BTP ABAP
Configuration	Every flag and env var, one table
Updating	Update procedures per install method
Enterprise Auth	Layer A / Layer B auth internals, coexistence matrix
Tool Reference	Complete reference for all 12 tools
Architecture	System architecture with diagrams
AI Usage Patterns	Agent workflow patterns and best practices

Development

npm ci && npm run build && npm test

See CLAUDE.md for codebase structure, testing commands, and contribution guidelines.

Credits

Project	Author	Contribution
vibing-steampunk	oisee	Original Go MCP server — ARC-1's starting point
abap-adt-api	Marcello Urbani	TypeScript ADT library, definitive API reference
mcp-abap-adt	Mario Andreschak	First MCP server for ABAP ADT
abaplint	Lars Hvam	ABAP parser/linter (used via @abaplint/core)

License

MIT