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Native Python, Java and Go runtime changes

Source-validation checkpoint: 2026-09-14. These are coordinated changes across langstitch-spec, langstitch-sdk, langstitch-spring-ai and langtailor. Publication completed on 2026-09-15 and was verified on 2026-09-20. Source validation, artifact publication and production acceptance are separate checkpoints.

Python SDK 0.3.2, Java compiler 0.2.2 and shared spec 2.2.0 have been published. LangTailor 0.4.0 is available for Windows x64 and macOS x64/ARM64, with the same VSIX published to VS Code Marketplace and Open VSX. The release includes updater files, checksums and a source/dependency manifest. Desktop installers are unsigned and macOS artifacts are not notarized.

Changes for graph authors

  • Three executable targets: the IR recognizes python-langstitch, spring-ai and go. LangTailor emits native applications for each target. Go applications do not require a Python or Java runtime.
  • Native implementations: function, inline-tool and code-transformer bodies are stored separately in bodiesByPlatform. Java/Go implementations must be supplied explicitly. Save/load preserves these bodies, component templates, typed configuration and modern runtime settings.
  • Working tools: Python MCP clients execute stdio, SSE and streamable HTTP sessions with validation, cleanup and timeouts. Java and Go HTTP registry tools execute JSON requests with error handling. Generated Python projects require SDK 0.3.2 or newer for the MCP adapter.
  • Honest capability checks: unsupported nodes, transports and missing native bodies fail export with an explanation. Java and Go MCP is still unsupported.
  • Build feedback: desktop and VS Code builds report real toolchain failures. Native previews use the selected language; native debugging and reverse sync report their current limitations.

API compatibility

New clients should invoke every target using the common envelope:

POST /invoke
Content-Type: application/json
X-API-Key: <configured environment value>

{"state":{"query":"hello"}}

A successful response has {"result": {...state...}}. Java's legacy input/query requests and Go's raw-state requests remain accepted with their legacy response formats. GET /health supports startup checks. Authentication defaults require an API key; disabling it requires security.auth: "none".

Validation and limits

The Windows workspace verification completed 12 checks with no failing exit codes: 25 shared-spec tests, 200 SDK tests, 12 native Java tests, 103 IDE tests, SDK package validation and IDE source builds. Generated applications were compiled and executed with actual Python, Java and Go toolchains. Two SDK tests were intentionally skipped because they test the absence of optional dependencies, which were installed in this run.

This does not certify full feature or deployment parity. RAG/agent exports, native MCP, durable cross-language checkpointing, streaming/event parity, native subgraphs/HITL/classifiers, Go pack compilation, reverse sync and native debugging remain incomplete. Native generated-application conformance passed on Ubuntu, Windows and macOS before publication. GUI installer acceptance, container startup, live provider credentials and production load/recovery testing remain open. Desktop dependency maintenance also remains open; see the readiness record.

See Production readiness for detailed behavior, authoring examples, release ordering and reproducible checks. Coordinate the specification, SDK, Java compiler and IDE versions when releasing; an IDE export must not depend on an SDK version absent from the package index it uses.