Fix flaky CompactionTest: wait for async compaction complete event before asserting

[Copilot]

Before the change?

testShouldTriggerCompactionWithLowThresholdAndEmitEvents was failing intermittently in the github/copilot-sdk-java CI environment with compactionCompleteCount == 0, even though compactionStartCount >= 1. The SessionCompactionCompleteEvent can arrive slightly after sendAndWait returns its session.idle signal due to async event delivery from the CLI — the test was asserting immediately without accounting for this race condition.

After the change?

CompactionTest.java — a CountDownLatch is added to explicitly wait up to 10 seconds for SessionCompactionCompleteEvent before making assertions:

var compactionCompleteLatch = new CountDownLatch(1);

session.on(event -> {
    events.add(event);
    if (event instanceof SessionCompactionCompleteEvent) {
        compactionCompleteLatch.countDown();
    }
});

// ... sendAndWait calls ...

// Wait up to 10s for async compaction complete delivery before asserting
assertTrue(compactionCompleteLatch.await(10, TimeUnit.SECONDS),
        "Should have received a compaction complete event within 10 seconds");

This is a timing robustness fix — the test logic is unchanged, it just no longer races against async event delivery. The 10-second window sits well inside the 120-second @Timeout.

The fix was applied to branch edburns/dd-2785864-pre-public-non-code-changes via cherry-pick of commit c76dbe8ce.

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

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[edburns]

@copilot Please merge these changes into edburns/dd-2785864-pre-public-non-code-changes and close this pull request. Do not delete the topic branch. I must inspect the merge. I do not want this work to be lost until I do that,.

[Copilot]

@copilot Please merge these changes into edburns/dd-2785864-pre-public-non-code-changes and close this pull request. Do not delete the topic branch. I must inspect the merge. I do ...

The agent environment only allows pushing to the PR branch (copilot/copilot20260312-dd-2825129-fix-test-failures), so I cannot directly push to edburns/dd-2785864-pre-public-non-code-changes.

The fix is entirely contained in a single commit — c76dbe8ce — which changes only src/test/java/com/github/copilot/sdk/CompactionTest.java. To apply it to your branch and close this PR, you can run:

git checkout edburns/dd-2785864-pre-public-non-code-changes
git cherry-pick c76dbe8ced3237838fdbe69a0a0e2fa5aabe67d4
git push origin edburns/dd-2785864-pre-public-non-code-changes

After that you can close this PR. I have not deleted the topic branch.