[Java] Embed Rust CLI runtime 4.7: Native binary download and classifier JAR module

[edburns]

Overview

Create the copilot-native/ Maven module (com.github:copilot-sdk-java-runtime) that downloads the runtime.node binary for linux-x64 only via npm pack and packages it as a linux-x64 classifier JAR with SHA-512 integrity verification.

This is task 4.7 of 9 in the implementation plan. Tasks are assigned, completed, and merged serially in this listed order. Tasks 4.1–4.6 are complete on the base branch before this task begins.

Branch: edburns/1917-java-embed-rust-cli-runtime-dd-3039145 on upstream

Plan and supporting resources

On the edburns/1917-java-embed-rust-cli-runtime-dd-3039145 branch, the directory 1917-java-embed-rust-cli-runtime-remove-before-merge contains the plan (1917-embed-cli-runtime-ignorance-reduction-plan.md) and supporting resources (spikes, prototypes, diagrams).

Read the entire plan before working.

Relevant plan sections to carefully re-read

• Section 3.1 — Maven module structure — Resolution: Option B — multi-module reactor. copilot-native module uses multiple maven-jar-plugin executions per platform. Plus a placeholder primary JAR. The copilot-native-all uber-JAR module is deferred.
• Section 3.2 — How do native binaries enter the build — Resolution: Option C variant — npm pack per-platform via exec-maven-plugin. SHA-512 integrity verification against nodejs/package-lock.json. Temporary invariant: linux-x64 only. Node.js is required for this module but NOT for the main SDK.
• Section 4.7 — Native binary download and classifier JAR module (the primary task description).
• Hard scope invariant (Phase 4 preamble): All native implementation work is limited to Ubuntu 24.04 on linux-x64 only. Other platforms are out of scope.

Resolved decisions that constrain this task

• Module GAV: com.github:copilot-sdk-java-runtime
• Version alignment: ${project.version} matches the npm @github/copilot-<platform> package version. No separate version property needed.
• Download mechanism: npm pack @github/copilot-linux-x64@${project.version} in generate-resources phase via exec-maven-plugin.
• Staging path: target/native-staging/linux-x64/native/linux-x64/runtime.node (after tar extraction).
• Integrity verification: Read integrity field (SHA-512) from ${copilot.sdk.root}/nodejs/package-lock.json for @github/copilot-linux-x64. Verify downloaded .tgz against it.
• Placeholder primary JAR: Contains only native/lib/copilot-runtime.properties with placeholder=true. Satisfies Maven Central validation.
• Classifier JAR: One maven-jar-plugin execution with <classifier>linux-x64</classifier>, packaging from target/native-staging/linux-x64/.
• Resource path convention: native/<classifier>/runtime.node and native/<classifier>/platform.properties (containing classifier=linux-x64 and version=${project.version}).
• Node.js dependency: Required for this module. Already required for Java E2E tests (replay proxy), so no new build dependency introduced.
• Module can be skipped: Developers working only on SDK Java code can run mvn -pl sdk to skip this module entirely.

Deliverables

Files to create

1. java/copilot-native/pom.xml — Module POM with:

   • Parent: copilot-sdk-java-parent
   • GAV: com.github:copilot-sdk-java-runtime
   • exec-maven-plugin in generate-resources phase: runs npm pack @github/copilot-linux-x64@${project.version}
   • tar extraction step to target/native-staging/linux-x64/native/linux-x64/runtime.node
   • SHA-512 integrity verification step reading from ${copilot.sdk.root}/nodejs/package-lock.json
   • Default maven-jar-plugin execution producing placeholder primary JAR
   • Additional maven-jar-plugin execution with <classifier>linux-x64</classifier>, packaging from target/native-staging/linux-x64/
   • Optional: build-helper-maven-plugin wiring prepared for future Gradle Module Metadata expansion

2. java/copilot-native/src/main/resources/native/lib/copilot-runtime.properties — Placeholder properties file: placeholder=true, version=${project.version}

3. Platform properties for the classifier JAR — The build step must produce native/linux-x64/platform.properties containing:

   classifier=linux-x64
   version=${project.version}

Files to modify

4. java/pom.xml (parent POM) — Uncomment/add copilot-native in <modules>. Ensure copilot.sdk.root property is defined so the native module can reference nodejs/package-lock.json.

Gating tests and criteria

1. Classifier JAR produced: mvn package -pl copilot-native produces the linux-x64 classifier JAR containing native/linux-x64/runtime.node.
2. Placeholder JAR produced: The primary JAR contains native/lib/copilot-runtime.properties and NO native binaries.
3. SHA-512 verification passes: The integrity hash from nodejs/package-lock.json matches the downloaded .tgz.
4. Reactor build: mvn clean verify from java/ runs the full reactor (including this module).
5. SDK-only build: mvn -pl sdk clean verify still works (skipping the native module).
6. All prior tests pass: mvn verify from java/ passes.

Out of scope

• Building classifier JARs for any platform other than linux-x64 (deferred to later phase).
• Monolithic uber-JAR assembly (copilot-native-all module) — deferred.
• Gradle Module Metadata (.module) file — deferred (wiring can be prepared but not activated).
• Publishing to Maven Central — separate workflow concern.