[java] Add linux-x64 implementation of in process Copilot CLI (#2301)

* feat(java): embed Rust CLI runtime as native module

Squashed from PR #2295 (branch edburns/…-review-02).
Includes Java multi-module Maven restructure, copilot-native
submodule for bundling the Rust CLI runtime, codegen updates,
and related workflow changes.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 90cbda40-cda3-4ecd-b381-9f9ba0573d0a

* java: add flatten-maven-plugin to produce self-contained deployed POMs

Child modules (copilot-sdk-java, copilot-sdk-java-runtime) inherit from
copilot-sdk-java-parent, which is not published to Maven Central. Without
flattening, consumers resolving a child artifact would fail to resolve the
parent POM. The flatten-maven-plugin (ossrh mode) inlines all inherited
metadata so the deployed POM is fully self-contained.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 3a69f33e-eea6-4b8c-9ef0-8b4d56d53a9c

* java: only release callback GC root after successful connection_close

Previously the tracked callback was removed in a finally block,
releasing its GC root even when native connection_close failed or threw.
Native code could still retain and invoke the stale function pointer,
crashing the JVM after JNA collected the callback.

Now the callback reference is only removed from trackedCallbacks when the
native call succeeds, ensuring the function pointer stays rooted while
native code may still hold it.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 3a69f33e-eea6-4b8c-9ef0-8b4d56d53a9c

* java: remove spike test library references, use real native runtime

Remove CallbackTestLib interface and all tests that depended on the
spike libcallback_test.so from the removed
1917-java-embed-rust-cli-runtime-remove-before-merge directory.

Rewrite the 3 duplicate-load guard tests to use NativeRuntimeLoader.resolve()
to locate the real runtime.node binary instead of the spike library.

Remove the startWithSpikeLibrarySupportsLifecycleAndDataFlow integration
test from FfiRuntimeHostTest — this functionality is covered by E2E tests.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 3a69f33e-eea6-4b8c-9ef0-8b4d56d53a9c

* docs: add JNA dependency to in-process mode README snippet

JNA is declared optional in the SDK POM so subprocess-mode users don't
pull it transitively. The in-process mode section was missing this
required third dependency, which would cause NoClassDefFoundError at
runtime.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 3a69f33e-eea6-4b8c-9ef0-8b4d56d53a9c

* java: add empty javadoc and sources JARs for copilot-native module

Maven Central requires javadoc and sources classifier JARs for every
non-POM artifact. Since copilot-native has no Java sources, the parent's
maven-javadoc-plugin produced nothing. Add explicit empty-archive
executions to maven-jar-plugin so the module passes Central validation.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 3a69f33e-eea6-4b8c-9ef0-8b4d56d53a9c

* java: use size_t-width type for native length parameters

The C ABI declares all buffer-length parameters as size_t (8 bytes on
64-bit), but the Java FFI layer was using int (always 4 bytes). While
harmless for current JSON-RPC payloads, this is incorrect on 64-bit
platforms and would be wrong on Windows x64 where NativeLong (C long)
is also only 4 bytes.

Introduce SizeT, a minimal IntegerType subclass sized via
Native.SIZE_T_SIZE, and use it in CopilotRuntimeLibrary and
OutboundCallback. The NativeBinding Java abstraction layer keeps int
parameters; JnaNativeBinding converts at the boundary.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 3a69f33e-eea6-4b8c-9ef0-8b4d56d53a9c

* java: remove global JNA callback exception handler

The process-wide Native.setCallbackExceptionHandler was redundant: the
local catch (Throwable) in createOutboundCallback() already prevents any
exception from escaping across the FFI boundary. The global mutation
affected unrelated JNA callbacks in the same process and was never
restored.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 3a69f33e-eea6-4b8c-9ef0-8b4d56d53a9c

* ci: make java-sdk-inprocess test job blocking

Remove continue-on-error so FFI regressions in the in-process transport
block PRs. The in-process transport is now production code and must not
silently regress.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 3a69f33e-eea6-4b8c-9ef0-8b4d56d53a9c

* fix: update jbang-example.java path after move to sdk/ submodule

The JBang example moved from java/jbang-example.java to
java/sdk/jbang-example.java but two references were not updated:
the runnable JBang URL in README.md and the release workflow's
update-documentation-versions script invocation.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 3a69f33e-eea6-4b8c-9ef0-8b4d56d53a9c

* docs: fix ADR relative links in README

The ADRs are at java/docs/adr/, not java/sdk/docs/adr/. Fix the
relative links for ADR-006 and ADR-004.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 3a69f33e-eea6-4b8c-9ef0-8b4d56d53a9c

* Regenerate Java codegen output

Auto-committed by java-codegen-check workflow.

* fix(java): retain JNA callbacks for process lifetime

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 108d08d4-0724-4414-bed8-2771b12b58de

* fix(java): publish executable CLI atomically

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 108d08d4-0724-4414-bed8-2771b12b58de

* docs(java): align native runtime ADR

Document strict in-process selection, the implemented runtime resolution order, current artifact contents, and the intentionally narrow PATH compatibility fallback.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 108d08d4-0724-4414-bed8-2771b12b58de

* fix(java): key native cache by runtime version

Read the packaged native version before cache lookup so mutable SDK snapshot builds cannot reuse stale runtime and CLI artifacts.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 108d08d4-0724-4414-bed8-2771b12b58de

* fix(java): validate staged native artifacts

Include the bundled CLI digest in the incremental staging stamp, require complete platform metadata, and verify the classifier JAR contains the CLI.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 108d08d4-0724-4414-bed8-2771b12b58de

* fix(java): complete Maven module migration

Restore pre-migration dependency and plugin versions, publish correct child project metadata, and update repository consumers to the moved SDK paths.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 108d08d4-0724-4414-bed8-2771b12b58de

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Copilot-Session: 90cbda40-cda3-4ecd-b381-9f9ba0573d0a
Copilot-Session: 3a69f33e-eea6-4b8c-9ef0-8b4d56d53a9c
Copilot-Session: 108d08d4-0724-4414-bed8-2771b12b58de

Author: 3 people

.githooks/pre-commit

@@ -1,14 +1,14 @@
 #!/bin/sh
 #
 # Pre-commit hook that runs Spotless check on the Java SDK when Java source
-# files are staged. Only triggers if changes exist under java/src/.
+# files are staged. Only triggers if changes exist under java/sdk/src/.
 #
 # To install this hook, run from the repository root:
 #   git config core.hooksPath .githooks
 #
 
-# Only run Spotless if staged changes include Java source files under java/src/
-if ! git diff --cached --name-only | grep -q '^java/src/'; then
+# Only run Spotless if staged changes include Java source files under java/sdk/src/
+if ! git diff --cached --name-only | grep -q '^java/sdk/src/'; then
     exit 0
 fi
 

.github/actions/java-test-report/action.yml

@@ -4,15 +4,15 @@ inputs:
   report-path:
     description: "Path to the test report XML files (glob pattern)"
     required: false
-    default: "java/target/{surefire-reports*,failsafe-reports}/TEST-*.xml"
+    default: "java/sdk/target/{surefire-reports*,failsafe-reports}/TEST-*.xml"
   jacoco-path:
     description: "Path to the JaCoCo XML report"
     required: false
-    default: "java/target/site/jacoco-coverage/jacoco.xml"
+    default: "java/sdk/target/site/jacoco-coverage/jacoco.xml"
   jacoco-csv-path:
     description: "Path to the JaCoCo CSV report"
     required: false
-    default: "java/target/site/jacoco-coverage/jacoco.csv"
+    default: "java/sdk/target/site/jacoco-coverage/jacoco.csv"
   check-name:
     description: "Name for the check run"
     required: false

.github/copilot-instructions.md

@@ -11,7 +11,7 @@
 
 - Top-level: `README.md` (architecture + quick start)
 - Language entry points: `nodejs/src/client.ts`, `python/README.md`, `go/README.md`, `dotnet/README.md`
-- Java: `java/README.md`, `java/pom.xml`
+- Java: `java/README.md`, `java/pom.xml`, `java/sdk/pom.xml`, `java/copilot-native/pom.xml`
 - Test harness & E2E: `test/harness/*`, Python harness wrapper `python/e2e/testharness/proxy.py`
 - Schemas & type generation: `nodejs/scripts/generate-session-types.ts`
 - Session snapshots used by E2E: `test/snapshots/` (used by the replay proxy)
@@ -39,7 +39,7 @@
 - E2E runs against a local **replaying CAPI proxy** (see `test/harness/server.ts`). Most language E2E harnesses spawn that server automatically (see `python/e2e/testharness/proxy.py`).
 - Tests rely on YAML snapshot exchanges under `test/snapshots/` — to add test scenarios, add or edit the appropriate YAML files and update tests.
 - The harness prints `Listening: http://...` — tests parse this URL to configure CLI or proxy.
-- Java E2E tests use `E2ETestContext` which manages a `CapiProxy` (Node.js replaying proxy). The harness is cloned during Maven's `generate-test-resources` phase to `java/target/copilot-sdk/`.
+- Java E2E tests use `E2ETestContext` which manages a `CapiProxy` (Node.js replaying proxy). The harness is cloned during Maven's `generate-test-resources` phase to `java/sdk/target/copilot-sdk/`.
 - Java test method names are converted to lowercase snake_case for snapshot filenames (avoids case collisions on macOS/Windows).
 
 ## Project-specific conventions & patterns ✅
@@ -61,13 +61,13 @@
 
 ## Where to add new code or tests 🧭
 
-- SDK code: `nodejs/src`, `python/copilot`, `go`, `dotnet/src`, `rust/src`, `java/src/main/java`
-- Unit tests: `nodejs/test`, `python/*`, `go/*`, `dotnet/test`, `rust/tests`, `java/src/test/java`
-- E2E tests: `*/e2e/` folders that use the shared replay proxy and `test/snapshots/`, `java/src/test/java/**/e2e/`
-- Generated types: update schema in `@github/copilot` then run `cd nodejs && npm run generate:session-types` and commit generated files in `src/generated` or language generated location. Java generated types: `java/src/generated/java`
+- SDK code: `nodejs/src`, `python/copilot`, `go`, `dotnet/src`, `rust/src`, `java/sdk/src/main/java`
+- Unit tests: `nodejs/test`, `python/*`, `go/*`, `dotnet/test`, `rust/tests`, `java/sdk/src/test/java`
+- E2E tests: `*/e2e/` folders that use the shared replay proxy and `test/snapshots/`, `java/sdk/src/test/java/**/e2e/`
+- Generated types: update schema in `@github/copilot` then run `cd nodejs && npm run generate:session-types` and commit generated files in `src/generated` or language generated location. Java generated types: `java/sdk/src/generated/java`
 
 ## Boundaries — files you must NOT hand-edit ⛔
 
-- `java/src/generated/java/` — auto-generated by `scripts/codegen/java.ts`; regenerate with `cd java && mvn generate-sources -Pcodegen`.
+- `java/sdk/src/generated/java/` — auto-generated by `scripts/codegen/java.ts`; regenerate with `cd java && mvn generate-sources -Pcodegen`.
 - `nodejs/src/generated/` — auto-generated by `npm run generate:session-types`.
 - `test/snapshots/` — authoritative test fixtures; add/edit YAML here to change E2E behavior, but don't delete without understanding downstream impact.

.github/skills/new-java-e2e-test-yaml-and-test/SKILL.md

@@ -54,7 +54,7 @@ conversations:
 
 ### Step 3: Create the Java IT test class
 
-Place it in `java/src/test/java/com/github/copilot/` with an `IT` suffix
+Place it in `java/sdk/src/test/java/com/github/copilot/` with an `IT` suffix
 (e.g., `MyFeatureIT.java`). The failsafe plugin picks up `*IT.java` files.
 
 **Template:**
@@ -141,12 +141,12 @@ mvn clean verify
 
 | What | Where |
 |------|-------|
-| Test context (manages proxy, workDir, CLI) | `java/src/test/java/com/github/copilot/E2ETestContext.java` |
-| Java proxy wrapper | `java/src/test/java/com/github/copilot/CapiProxy.java` |
+| Test context (manages proxy, workDir, CLI) | `java/sdk/src/test/java/com/github/copilot/E2ETestContext.java` |
+| Java proxy wrapper | `java/sdk/src/test/java/com/github/copilot/CapiProxy.java` |
 | Replay proxy (TypeScript) | `test/harness/replayingCapiProxy.ts` |
 | Proxy server entry point | `test/harness/server.ts` |
 | Snapshot files | `test/snapshots/<category>/<name>.yaml` |
-| Existing IT tests for reference | `java/src/test/java/com/github/copilot/*IT.java` |
+| Existing IT tests for reference | `java/sdk/src/test/java/com/github/copilot/*IT.java` |
 
 ## How the Proxy Matches Requests
 

.github/workflows/codegen-check.yml

@@ -15,7 +15,7 @@ on:
       - 'go/rpc/**'
       - 'rust/src/generated/**'
       - 'sdk-protocol-version.json'
-      - 'java/src/main/java/com/github/copilot/SdkProtocolVersion.java'
+      - 'java/sdk/src/main/java/com/github/copilot/SdkProtocolVersion.java'
       - '.github/workflows/codegen-check.yml'
   workflow_dispatch:
 
@@ -84,7 +84,7 @@ jobs:
       - name: Verify Java protocol version matches
         run: |
           EXPECTED=$(jq -r '.version' sdk-protocol-version.json)
-          ACTUAL=$(grep -oP 'LATEST\(\K[0-9]+' java/src/main/java/com/github/copilot/SdkProtocolVersion.java)
+          ACTUAL=$(grep -oP 'LATEST\(\K[0-9]+' java/sdk/src/main/java/com/github/copilot/SdkProtocolVersion.java)
           if [ "$EXPECTED" != "$ACTUAL" ]; then
             echo "::error::Java SDK protocol version ($ACTUAL) does not match sdk-protocol-version.json ($EXPECTED). Java manages its own SdkProtocolVersion.java via java/scripts/codegen/. Update it to match."
             exit 1

.github/workflows/docs-validation.yml

@@ -9,8 +9,9 @@ on:
       - 'python/copilot/**'
       - 'go/**/*.go'
       - 'dotnet/src/**'
-      - 'java/src/**'
+      - 'java/sdk/src/**'
       - 'java/pom.xml'
+      - 'java/sdk/pom.xml'
       - 'scripts/docs-validation/**'
       - '.github/workflows/docs-validation.yml'
   workflow_dispatch:

.github/workflows/java-adapt-handwritten-code-to-accept-upgrade-changes.lock.yml

@@ -51,17 +51,17 @@ You are an automation agent that fixes handwritten Java SDK source and test code
 
 - The branch `${{ inputs.branch }}` already has:
   - Updated `java/scripts/codegen/package.json` with the new version
-  - Regenerated `java/src/generated/java/` code that compiles successfully
+  - Regenerated `java/sdk/src/generated/java/` code that compiles successfully
   - Updated the Java POM CLI/version pin property
 - Your job is ONLY to fix **handwritten** code, NOT generated code.
 
 ## Boundaries
 
-- ❌ Do NOT edit anything under `java/src/generated/java/`
+- ❌ Do NOT edit anything under `java/sdk/src/generated/java/`
 - ❌ Do NOT edit `java/scripts/codegen/java.ts`
-- ❌ Do NOT create or modify tests in the `com.github.copilot.generated` test package (`java/src/test/java/com/github/copilot/sdk/generated/`)
-- ✅ DO edit `java/src/main/java/com/github/copilot/sdk/**`
-- ✅ DO edit `java/src/test/java/com/github/copilot/sdk/**` (excluding the `generated` subpackage)
+- ❌ Do NOT create or modify tests in the `com.github.copilot.generated` test package (`java/sdk/src/test/java/com/github/copilot/sdk/generated/`)
+- ✅ DO edit `java/sdk/src/main/java/com/github/copilot/sdk/**`
+- ✅ DO edit `java/sdk/src/test/java/com/github/copilot/sdk/**` (excluding the `generated` subpackage)
 - ✅ DO add new test methods or test classes if new user-facing API surface is introduced
 
 ## Instructions
@@ -146,7 +146,7 @@ mvn verify -Dskip.test.harness=true
 If this passes, commit and push:
 
 ```bash
-git add java/src/main/java java/src/test/java
+git add java/sdk/src/main/java java/sdk/src/test/java
 git commit -m "Fix handwritten Java code for @github/copilot schema changes
 
 Adapt constructor calls, enum references, and test assertions to match

.github/workflows/java-adapt-handwritten-code-to-accept-upgrade-changes.md

@@ -6,12 +6,12 @@ on:
       - main
     paths:
       - 'java/scripts/codegen/**'
-      - 'java/src/generated/**'
+      - 'java/sdk/src/generated/**'
       - '.github/workflows/java-codegen-check.yml'
   pull_request:
     paths:
       - 'java/scripts/codegen/**'
-      - 'java/src/generated/**'
+      - 'java/sdk/src/generated/**'
       - '.github/workflows/java-codegen-check.yml'
   workflow_dispatch: