Java: add Windows x64 in-process runtime and native classifier publishing

[edburns]

Fixes #2392 .

Summary

Adds win32-x64 as a supported target for the Java SDK's experimental in-process runtime, alongside the existing GNU/Linux linux-x64 target.

• Packages a Windows native classifier containing runtime.node, copilot.exe, and platform.properties.
• Selects and validates the host-appropriate classifier when Maven runs with -Pinprocess: linux-x64 on x64 glibc Linux and win32-x64 on x64 Windows.
• Updates native extraction/loading and tests for Windows filesystem, executable-name, loaded-DLL, and atomic-move behavior.
• Runs the Java in-process test suite on both Ubuntu and Windows and adds blocking publication-assembly coverage.
• Builds each classifier on its native runner, verifies source/version identity, checksums, expected contents, and cross-classifier contamination, then publishes both classifiers in one Maven deployment.
• Applies that coordinated publication model to Maven Central snapshots and releases, including signed local-publication validation and one post-deployment summary covering every published classifier.
• Documents Windows x64 dependencies and updates ADR-007's supported-platform status.

User experience

In-process mode remains opt-in and the SDK's default connection behavior is unchanged. Applications enable it by:

1. Depending on com.github:copilot-sdk-java-runtime with the target classifier (linux-x64 or win32-x64) plus JNA.
2. Configuring CopilotClientOptions with RuntimeConnection.forInProcess().

For SDK development, mvn -Pinprocess clean verify automatically exercises the native runtime appropriate to the supported host. Unsupported OS/architecture/libc combinations fail validation instead of silently packaging the wrong native binary.

Publication model

Windows builds and uploads only the win32-x64 classifier and its checksum. Ubuntu independently builds linux-x64, verifies the Windows handoff came from the same immutable source and version, attaches it to the reactor, and performs a single deployment. This ensures snapshot coordinates share one Maven timestamp/build number and release signing covers both classifiers.

Scheduled snapshot publication remains restricted naturally to the default branch, while imperative workflow_dispatch runs can still publish from a selected non-default branch. Publication summaries are emitted only after Maven succeeds and list both classifier filenames and SHA-256 hashes without duplicate per-job callouts.

During the active Rust migration, each classifier intentionally includes the version-matched copilot/copilot.exe embedded-host executable in addition to runtime.node. The executable can be removed once the native runtime no longer delegates unported method bodies to the CLI.

Validation

• Native packaging script suite: 29 tests passing.
• Full Windows x64 mvn -Pinprocess clean verify reactor run.
• Host-matched Linux/Windows in-process Actions matrix.
• Local signed Maven publication containing the primary artifact, POM, sources, Javadoc, and both native classifiers with signatures.
• Topic-branch snapshot publication produced linux-x64 and win32-x64 under one snapshot build: https://github.com/github/copilot-sdk/actions/runs/32891483956

[Copilot]

Pull request overview

Extends Java’s experimental in-process runtime packaging from Linux x64 to Windows x64 while preserving host-gated builds.

Changes:

• Adds Windows classifier packaging and host validation.
• Expands loader tests and CI to Windows.
• Updates user and architecture documentation.

Show a summary per file

File	Description
.github/workflows/java-sdk-tests.yml	Adds Windows in-process CI.
java/copilot-native/pom.xml	Adds Windows native packaging profile.
java/copilot-native/scripts/fetch-native.test.mjs	Tests Windows artifact staging.
java/copilot-native/scripts/validate-native-host.mjs	Validates Windows x64 hosts.
java/copilot-native/scripts/validate-native-host.test.mjs	Tests Windows host validation.
java/docs/adr/adr-007-native-bundling-strategy.md	Documents Windows classifier support.
java/README.md	Adds Windows setup guidance.
java/sdk/pom.xml	Selects the host classifier for tests.
java/sdk/src/main/java/com/github/copilot/ffi/NativeRuntimeLoader.java	Handles Windows publication races.
java/sdk/src/test/java/com/github/copilot/ffi/JnaNativeBindingTest.java	Supports Windows library locking.
java/sdk/src/test/java/com/github/copilot/ffi/NativeRuntimeLoaderTest.java	Makes loader tests platform-aware.
2323-java-windows-x64-embed-rust-remove-before-merge/20260824-ghcp-sdk-2323-prompt.md	Temporary task prompt.
2323-java-windows-x64-embed-rust-remove-before-merge/20260816-notes-to-linux-x64-agent.md	Temporary Linux validation notes.
2323-java-windows-x64-embed-rust-remove-before-merge/20260815-make-it-so-no-incorrect-os-arch-artifacts-are-produced.md	Temporary implementation plan.

Review details

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• Files reviewed: 14/15 changed files
• Comments generated: 4
• Review effort level: Balanced

[github-actions]

SDK Consistency Review ✅

This PR adds Windows x64 native (Rust JNI) library embedding to the Java SDK — infrastructure work specific to Java's NativeRuntimeLoader and the CI/CD pipeline for publishing native classifiers.

No cross-SDK consistency issues found. The changes are:

• Platform-specific native library loading (AccessDeniedException handling, Windows temp-dir extraction)
• Java publish workflows and native artifact validation scripts
• ADR documentation for the bundling strategy

This is Java-internal infrastructure (how the Java SDK loads its Rust JNI binding). The other SDKs (Node.js, Python, Go, .NET, Rust) do not have an equivalent JNI layer — they interact with the Copilot CLI via JSON-RPC or link Rust natively — so no parallel changes are needed elsewhere.

Generated by SDK Consistency Review Agent for #2393 · sonnet46 19 AIC · ⌖ 5.36 AIC · ⊞ 6.6K · ◷