Choose a compatible contract.

Product scope and interface versions

LeanCTX provides context retrieval and preparation, source and content controls, governed execution, cost and outcome evidence, and portable state. Community, Enterprise and SDK/OEM describe how you use and operate that Engine.

An interface version determines how your code calls those capabilities. A release number, enabled feature profile, source policy and platform support are separate checks.

Surface	Check before connecting
CLI and MCP	Installed Engine version, enabled tool profile and exact command or parameter schema
SDK	Package, Engine companion, interface, schema and transport compatibility
Proxy and model routing	Supported request path, approved providers, identity and execution policy
Enterprise Engine	Deployment profile, organizational identity, entitlement and enabled policies
State transfer	Workspace/checkpoint format, supported migration, source references and recipient scope

Use the architecture guide to understand the shared flow and the relevant reference for exact syntax.

Capability negotiation

Match the contract reported by the Engine with the contract expected by the client. A newer version number alone does not establish compatibility. Handle an unsupported capability or protocol mismatch explicitly.

Tool registration also differs from API support: a diagnostic command, compatibility alias or local bus operation is not automatically a public SDK method.

Older names such as ctx_smart_read, ctx_multi_read, ctx_semantic_search and ctx_symbol are compatibility aliases. Prefer the documented ctx_read and ctx_search interfaces for the version in use.

Platform and deployment boundaries

Core installation supports Windows, macOS and Linux. Native artifacts, service managers, shell hooks and OS isolation differ. Match the SDK package to its published platform matrix as well as the Engine release.

Local processing does not make external sources or remote model calls offline. An offline deployment must use the corresponding artifacts, entitlement profile and permitted local dependencies.

See platforms and paths and organizational deployment.

Reference snapshots

Exact CLI/configuration captures and code examples keep their recorded versions. They are reference snapshots, not a statement that the website’s full Engine scope was already included in each historical release.

Reference	Captured baseline
CLI help and configuration	Runtime 3.10.2
MCP and command inventory	Source 5198ea1867, captured 18 September 2026; source package 3.9.20
Pinned Python SDK examples	SDK 1.1.0, source 4aba145627, Agent Tools companion Engine 3.10.1

Guides identify their own reference scope. Use the compatibility matrix and reference shipped with your selected release before copying a version-pinned example. Release history retains the availability and API commitments stated at the time of that release.

Engine contract & references2 references · Reviewed 19 Sept 2026

• COMPATIBILITY.mdSDK / COMPATIBILITY.mdGitHub
• PUBLIC-SURFACE-MANIFEST.mdSDK / PUBLIC-SURFACE-MANIFEST.mdGitHub

Engine concepts describe responsibilities and behavior. Exact commands, package versions and platform contracts belong to their versioned references.

Versions & compatibility