agentHost: fix customization watcher test session cleanup

[Christof Marti (chrmarti)]

Summary

Fix the macOS Electron customization watcher failure from Azure build 475402.

Retained diagnostics from build 475420 exposed the teardown bug: every disposeSession request sent the obsolete { session } parameter. The protocol expects { channel }, so the server was successfully disposing file:///undefined, leaving the actual sessions and their discovery watchers alive while the test deleted their workspace folders. Subsequent tests accumulated stale discovery scans and overlapping watchers.

• Dispose the actual session channel, checked against DisposeSessionParams.
• Await the matching root/sessionRemoved notification before deleting temporary workspaces so a success-shaped no-op cannot pass teardown again.
• Make instruction edits observable in both scan and SDK discovery modes by asserting changed applyTo globs. SDK discovery labels instructions by filename, so the old name-only assertion could pass without any refresh.
• Use concrete glob patterns because the SDK normalizes **/* away.

Temporary production trace instrumentation used during the investigation has been removed. The net change is confined to the customization integration test; no production behavior or skipped-test changes. Watcher timeouts are unchanged; teardown uses the existing setup timeout so its disposal assertions can finish.

Validation

• Focused watcher tests, ESLint, commit hygiene, and full npm run typecheck-client passed.
• Full customization suite with real session cleanup: 20 passing.
• Negative teardown control: restoring the obsolete parameter fails the removal-notification assertion; generated output restored afterward.
• Five focused repetitions on the final cleanup fix: 10/10 passing. A negative control also verified that unchanged globs fail at the edit assertion.
• Final macOS Azure CI validation: build 475433 succeeded. Both instruction watcher tests passed; the serial node integration suite finished with 644 passing. Publishing and releases were disabled.

[Copilot]

Copilot review overview

🟢 Approval recommended

The focused test-only changes correctly address the watcher race without weakening coverage or altering production behavior.

Review effort: Balanced
Findings: None

What changed in this PR

Stabilizes Copilot customization watcher integration tests by ensuring instruction edits produce observable state changes.

Changes:

• Uses concrete Markdown and TypeScript glob patterns.
• Verifies published rule globs before testing creation and deletion.

File	Description
copilotCustomizations.integrationTest.ts	Makes instruction watcher assertions reliably detect edits.

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[github-actions]

Base: dc9db4a0 Current: 7a6e11bf

No screenshot changes.

[Christof Marti (chrmarti)]

Azure build 475418 confirms that the name-only assertion was hiding a missing refresh: with glob assertions, the test now times out on the edit itself. The initial test-only change is insufficient. Build 475420 adds retained watcher/discovery trace logs to investigate the underlying macOS failure. The local SDK dependency was also restored to the checkout version; focused tests still pass locally.