Add getSessionMetadata for O(1) session lookup by ID

[brunoborges]

Ports upstream copilot-sdk PR #899 to the Java SDK. Adds a new getSessionMetadata(String sessionId) method to CopilotClient that calls the session.getMetadata JSON-RPC endpoint for efficient O(1) single-session metadata lookup. Returns null when the session is not found (Java-idiomatic absent value).

---

Before the change?

• No way to look up a single session's metadata by ID — callers had to use listSessions() and filter client-side.

After the change?

• CopilotClient.java — New getSessionMetadata(String) method following the same pattern as listSessions/deleteSession
• GetSessionMetadataResponse.java — New response DTO record (@since 1.2.0) for the session.getMetadata RPC call
• SessionMetadata.java — Updated Javadoc with @see tag referencing the new method
• CopilotSessionTest.java — New @Disabled E2E test; disabled because the should_get_session_metadata snapshot was added by upstream PR #899 and won't be available until .lastmerge is advanced past that PR

Upstream reference

SDK	Method	Return type	Not-found value
Java	getSessionMetadata(sessionId)	CompletableFuture<SessionMetadata>	null

Pull request checklist

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)
• mvn spotless:apply has been run to format the code
• mvn clean verify passes locally

Does this introduce a breaking change?

• Yes
• No

---

---

🔒 GitHub Advanced Security automatically protects Copilot coding agent pull requests. You can protect all pull requests by enabling Advanced Security for your repositories. Learn more about Advanced Security.

[Copilot]

Pull request overview

Ports upstream support for O(1) session metadata lookup by adding a new CopilotClient#getSessionMetadata(String) API that calls the session.getMetadata JSON-RPC endpoint, plus the associated response DTO and test scaffolding.

Changes:

• Add CopilotClient#getSessionMetadata(String) that returns SessionMetadata (or null if not found).
• Introduce GetSessionMetadataResponse DTO for session.getMetadata RPC responses.
• Update SessionMetadata Javadoc and add a disabled E2E test for the new behavior.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
src/main/java/com/github/copilot/sdk/CopilotClient.java	Adds the new getSessionMetadata JSON-RPC wrapper method.
src/main/java/com/github/copilot/sdk/json/GetSessionMetadataResponse.java	Adds the RPC response record used to deserialize session.getMetadata results.
src/main/java/com/github/copilot/sdk/json/SessionMetadata.java	Updates Javadoc to reference the new lookup API.
src/test/java/com/github/copilot/sdk/CopilotSessionTest.java	Adds an (currently disabled) E2E test for session metadata lookup by ID.

[Copilot]

The @since tag is set to 1.0.0, but this response type (and CopilotClient#getSessionMetadata(String)) is being introduced in this PR. Please update @since to the version where this API is actually added (consistent with other newer additions that use @since 1.2.0, etc.).

Suggested change

	* @since 1.0.0
	* @since 1.2.0

[edburns]

Converting this to draft until the reference implementation PR github/copilot-sdk#899 is merged. @MackinnonBuck is still actively working on this.

[edburns]

@copilot In the time between when I most recently marked this as draft and now, the reference implementation did have github/copilot-sdk#899 merged. I believe there have been additional commits to that PR that need to be considered when making a complete implementation of that PR in this codebase.

Please analyze the PR and make sure you have picked up all the changes, making changes to your implementation as necessary.

[Copilot]

@copilot In the time between when I most recently marked this as draft and now, the reference implementation did have github/copilot-sdk#899 merged. I believe t...

Analyzed the final merged state of upstream PR #899 (10 commits, all 4 SDK languages). The Java implementation already matches the upstream API correctly — getSessionMetadata(sessionId) calls session.getMetadata and returns SessionMetadata or null.

Changes in 648e3f1:

• Fixed @since 1.0.0 → @since 1.2.0 on GetSessionMetadataResponse (per reviewer feedback)
• Updated @Disabled reason: the test is disabled because the should_get_session_metadata snapshot was added by upstream PR #899 and won't be available until .lastmerge is advanced past that PR
• Added @see for getSessionMetadata(String) in SessionMetadata Javadoc

Build passes: 463 tests, 0 failures, 1 skipped (the disabled snapshot test).