Add classical code generation workflow for Java SDK and migrate to generated event types

.gitattributes

@@ -1 +1,2 @@
-.github/workflows/*.lock.yml linguist-generated=true merge=ours
+.github/workflows/*.lock.yml linguist-generated=true merge=ours
+src/generated/java/** eol=lf linguist-generated=true

.github/copilot-instructions.md

@@ -77,7 +77,7 @@ mvn test -Dtest=CopilotClientTest
 
 - `com.github.copilot.sdk` - Core classes (CopilotClient, CopilotSession, JsonRpcClient)
 - `com.github.copilot.sdk.json` - DTOs, request/response types, handler interfaces (SessionConfig, MessageOptions, ToolDefinition, etc.)
-- `com.github.copilot.sdk.events` - Event types for session streaming (AssistantMessageEvent, SessionIdleEvent, ToolExecutionStartEvent, etc.)
+- `com.github.copilot.sdk.generated` - Generated event types for session streaming (SessionEvent, AssistantMessageEvent, SessionIdleEvent, ToolExecutionStartEvent, etc.)
 
 ### Test Infrastructure
 

.github/workflows/codegen-check.yml

@@ -0,0 +1,44 @@
+name: "Codegen Check"
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    paths:
+      - 'scripts/codegen/**'
+      - 'src/generated/java/**'
+      - '.github/workflows/codegen-check.yml'
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  check:
+    name: "Verify generated files are up-to-date"
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+
+      - uses: actions/setup-node@53b83947a5a98c8d113130e565377fae1a50d02f # v6
+        with:
+          node-version: 22
+
+      - name: Install codegen dependencies
+        working-directory: ./scripts/codegen
+        run: npm ci
+
+      - name: Run codegen
+        working-directory: ./scripts/codegen
+        run: npm run generate
+
+      - name: Check for uncommitted changes
+        run: |
+          if [ -n "$(git status --porcelain)" ]; then
+            echo "::error::Generated files are out of date. Run 'cd scripts/codegen && npm run generate' and commit the changes."
+            git diff --stat
+            git diff
+            exit 1
+          fi
+          echo "✅ Generated files are up-to-date"

.github/workflows/update-copilot-dependency.yml

@@ -0,0 +1,97 @@
+name: "Update @github/copilot Dependency"
+
+on:
+  workflow_dispatch:
+    inputs:
+      version:
+        description: 'Target version of @github/copilot (e.g. 1.0.24)'
+        required: true
+        type: string
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  update:
+    name: "Update @github/copilot to ${{ inputs.version }}"
+    runs-on: ubuntu-latest
+    steps:
+      - name: Validate version input
+        env:
+          VERSION: ${{ inputs.version }}
+        run: |
+          if [[ ! "$VERSION" =~ ^[0-9]+\.[0-9]+\.[0-9]+(-[a-zA-Z0-9._-]+)?$ ]]; then
+            echo "::error::Invalid version format '$VERSION'. Expected semver (e.g. 1.0.24)."
+            exit 1
+          fi
+
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+
+      - uses: actions/setup-node@53b83947a5a98c8d113130e565377fae1a50d02f # v6
+        with:
+          node-version: 22
+
+      - name: Update @github/copilot in scripts/codegen
+        env:
+          VERSION: ${{ inputs.version }}
+        working-directory: ./scripts/codegen
+        # npm install updates package.json and package-lock.json to the new
+        # version; npm ci (below) then does a clean, reproducible install from
+        # the updated lock file.  Both steps are required: npm install alone
+        # leaves leftover packages, while npm ci alone cannot change the pinned
+        # version in the lock file.
+        run: npm install "@github/copilot@$VERSION"
+
+      - name: Install codegen dependencies
+        working-directory: ./scripts/codegen
+        run: npm ci
+
+      - name: Run codegen
+        working-directory: ./scripts/codegen
+        run: npm run generate
+
+      - name: Create pull request
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          VERSION: ${{ inputs.version }}
+        run: |
+          BRANCH="update-copilot-$VERSION"
+          git config user.name "github-actions[bot]"
+          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+
+          if git rev-parse --verify "origin/$BRANCH" >/dev/null 2>&1; then
+            git checkout "$BRANCH"
+            git reset --hard HEAD
+          else
+            git checkout -b "$BRANCH"
+          fi
+
+          git add -A
+
+          if git diff --cached --quiet; then
+            echo "No changes detected; skipping commit and PR creation."
+            exit 0
+          fi
+
+          git commit -m "Update @github/copilot to $VERSION
+
+          - Updated @github/copilot in scripts/codegen
+          - Re-ran Java code generator"
+          git push origin "$BRANCH" --force-with-lease
+
+          if gh pr view "$BRANCH" >/dev/null 2>&1; then
+            echo "Pull request for branch '$BRANCH' already exists; updated branch only."
+          else
+            gh pr create \
+              --title "Update @github/copilot to $VERSION" \
+              --body "Automated update of \`@github/copilot\` to version \`$VERSION\`.
+
+          ### Changes
+          - Updated \`@github/copilot\` in \`scripts/codegen/package.json\`
+          - Re-ran Java code generator (\`scripts/codegen\`)
+
+          > Created by the **Update @github/copilot Dependency** workflow." \
+              --base main \
+              --head "$BRANCH"
+          fi

.gitignore

@@ -5,10 +5,11 @@ examples-test/
 blog-copilotsdk/
 .claude/worktrees
 smoke-test
-*job-logs.txt
+*job-logs.txt*
 temporary-prompts/
 changebundle.txt*
 .classpath
 .project
 .settings
+scripts/codegen/node_modules/
 *~

README.md

@@ -67,8 +67,8 @@ implementation 'com.github:copilot-sdk-java:0.2.2-java.1'
 
 ```java
 import com.github.copilot.sdk.CopilotClient;
-import com.github.copilot.sdk.events.AssistantMessageEvent;
-import com.github.copilot.sdk.events.SessionUsageInfoEvent;
+import com.github.copilot.sdk.generated.AssistantMessageEvent;
+import com.github.copilot.sdk.generated.SessionUsageInfoEvent;
 import com.github.copilot.sdk.json.CopilotClientOptions;
 import com.github.copilot.sdk.json.MessageOptions;
 import com.github.copilot.sdk.json.PermissionHandler;

config/checkstyle/checkstyle.xml

@@ -11,9 +11,9 @@
     <property name="charset" value="UTF-8"/>
     <property name="severity" value="error"/>
 
-    <!-- Exclude json package and events package (self-documenting DTOs) -->
+    <!-- Exclude json package, events package, and generated package (self-documenting DTOs) -->
     <module name="BeforeExecutionExclusionFileFilter">
-        <property name="fileNamePattern" value=".*[\\/](json|events)[\\/].*\.java$"/>
+        <property name="fileNamePattern" value=".*[\\/](json|events|generated|rpc)[\\/].*\.java$"/>
     </module>
 
     <module name="TreeWalker">

config/spotbugs/spotbugs-exclude.xml

@@ -2,15 +2,15 @@
 <!--
     SpotBugs exclusion filter for the Copilot SDK.
 
-    The 'events' and 'json' packages contain Jackson-deserialized DTOs where
+    The 'generated' and 'json' packages contain Jackson-deserialized DTOs where
     returning mutable internal representations (EI_EXPOSE_REP) and storing
     references to mutable objects (EI_EXPOSE_REP2) is intentional and expected.
     Making defensive copies would add overhead without meaningful security
     benefit for these read-only data transfer objects.
 -->
 <FindBugsFilter>
     <Match>
-        <Package name="com.github.copilot.sdk.events"/>
+        <Package name="com.github.copilot.sdk.generated"/>
         <Bug pattern="EI_EXPOSE_REP,EI_EXPOSE_REP2"/>
     </Match>
     <Match>

docs/WORKFLOWS.md

@@ -5,6 +5,8 @@
 | Workflow | Description | Triggers | Schedule |
 |----------|-------------|----------|----------|
 | [Build & Test](workflows/build-test.yml) | Builds, lints, and tests the Java SDK | `push` (main), `pull_request`, `merge_group`, `workflow_dispatch` | Sundays at 00:00 UTC |
+| [Codegen Check](workflows/codegen-check.yml) | Verifies that generated Java files are up-to-date with the JSON schemas | `push` (main), `pull_request`, `workflow_dispatch` | — |
+| [Update @github/copilot Dependency](workflows/update-copilot-dependency.yml) | Updates the `@github/copilot` npm package, re-runs code generation, and opens a PR | `workflow_dispatch` | — |
 | [Deploy Documentation](workflows/deploy-site.yml) | Generates and deploys versioned docs to GitHub Pages | `workflow_run` (after Build & Test), `release`, `workflow_dispatch` | — |
 | [Publish to Maven Central](workflows/publish-maven.yml) | Releases the SDK to Maven Central and creates a GitHub Release | `workflow_dispatch` | — |
 | [Weekly Reference Implementation Sync](workflows/weekly-reference-impl-sync.yml) | Checks for new reference implementation commits and creates an issue for Copilot to merge | `workflow_dispatch` | Mondays at 10:00 UTC |
@@ -87,6 +89,42 @@ Auto-generated compiled workflow produced by `gh aw compile` from the correspond
 
 ---
 
+## Codegen Check
+
+**File:** [`codegen-check.yml`](workflows/codegen-check.yml)
+
+Verifies that the generated Java source files in `src/generated/java/` are up-to-date with the JSON schemas distributed in the `@github/copilot` npm package.
+
+Steps:
+1. Installs the codegen dependencies from `scripts/codegen/`
+2. Runs the Java code generator (`npm run generate`)
+3. Fails with a diff if any generated file differs from what is committed
+
+Run this locally with:
+```bash
+cd scripts/codegen && npm ci && npm run generate
+```
+
+If changes appear, commit the updated generated files.
+
+---
+
+## Update @github/copilot Dependency
+
+**File:** [`update-copilot-dependency.yml`](workflows/update-copilot-dependency.yml)
+
+Manual workflow triggered when a new version of the `@github/copilot` npm package is published. Accepts a `version` input (e.g. `1.0.25`).
+
+Steps:
+1. Updates `@github/copilot` in `scripts/codegen/package.json`
+2. Re-runs the Java code generator
+3. Commits the updated `package.json`, `package-lock.json`, and all regenerated Java files
+4. Opens (or updates) a pull request for review
+
+The resulting PR will be automatically validated by the **Codegen Check** workflow.
+
+---
+
 ## Copilot Setup Steps
 
 **File:** [`copilot-setup-steps.yml`](workflows/copilot-setup-steps.yml)

jbang-example.java

@@ -1,8 +1,8 @@
 !
 //DEPS com.github:copilot-sdk-java:0.2.2-java.1
 import com.github.copilot.sdk.CopilotClient;
-import com.github.copilot.sdk.events.AssistantMessageEvent;
-import com.github.copilot.sdk.events.SessionUsageInfoEvent;
+import com.github.copilot.sdk.generated.AssistantMessageEvent;
+import com.github.copilot.sdk.generated.SessionUsageInfoEvent;
 import com.github.copilot.sdk.json.MessageOptions;
 import com.github.copilot.sdk.json.PermissionHandler;
 import com.github.copilot.sdk.json.SessionConfig;

pom.xml

@@ -255,12 +255,35 @@
                     </systemPropertyVariables>
                 </configuration>
             </plugin>
+            <!-- Add src/generated/java as an additional source root -->
+            <plugin>
+                <groupId>org.codehaus.mojo</groupId>
+                <artifactId>build-helper-maven-plugin</artifactId>
+                <version>3.6.1</version>
+                <executions>
+                    <execution>
+                        <id>add-generated-source</id>
+                        <phase>generate-sources</phase>
+                        <goals>
+                            <goal>add-source</goal>
+                        </goals>
+                        <configuration>
+                            <sources>
+                                <source>${project.basedir}/src/generated/java</source>
+                            </sources>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
             <plugin>
                 <groupId>com.diffplug.spotless</groupId>
                 <artifactId>spotless-maven-plugin</artifactId>
                 <version>2.44.5</version>
                 <configuration>
                     <java>
+                        <excludes>
+                            <exclude>src/generated/java/**/*.java</exclude>
+                        </excludes>
                         <eclipse>
                             <version>4.33</version>
                         </eclipse>

scripts/codegen/.gitignore

@@ -0,0 +1 @@
+node_modules/