test(proxy): allocate unique sub-agent id per test instance to deflake parallel runs

PipeDiscoveryServiceTests and PowerShellToolsTests both used the
constant agent id "default" while reaching into the static
ConsoleSessionManager.Instance for state mutations
(SetActivePipeName / SetLastAiCwd / MarkPipeBusy / ClearDeadPipe /
TryAssignNameToPid). xunit parallelizes test classes by default, so
two classes touching state keyed by the same "default" id can race —
seen in CI on Windows as a transient null AllPipesStatusInfo from
FindReadyPipeAsync_ActivePipeBusy_RecordsStatusInfo, while the same
test was green on the next run with no code change.

Switch to ConsoleSessionManager.Instance.AllocateSubAgentId() in each
class''s constructor (xunit creates a fresh instance per test method,
so each test gets its own id). The session manager already uses this
id everywhere as an opaque dictionary key, and IPipeDiscoveryService /
PowerShellTools accept any non-empty agent id once it''s in the
allocated set, so no production-code change is needed.

For PowerShellToolsTests the TestPipeName format string is also
derived from the new TestAgentId so any code that re-derives the
agent id from a pipe name segment sees a consistent value.

ConsoleSessionManagerTests was already mostly clean (it allocates
per-test ids via the same helper) so no change there. Its one
"default"-using test has a comment acknowledging the leak is benign
because no other test reads that key.

xunit local: net8 162/162, net9 275/275.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: yotsuda

Tests/Unit/Proxy/PipeDiscoveryServiceTests.cs

@@ -9,12 +9,18 @@ public class PipeDiscoveryServiceTests
 {
     private readonly Mock<IPowerShellService> _mockPowerShellService;
     private readonly PipeDiscoveryService _service;
-    private const string DefaultAgentId = "default";
+    // Allocate a unique sub-agent id per test instance (xunit creates one per test
+    // method) so concurrent test classes touching the static ConsoleSessionManager.Instance
+    // — which keys all state by agent id — can't trample each other. A previous run hit
+    // a flaky failure on Windows where another suite''s "default" entry had cleared this
+    // class''s active-pipe registration mid-test. The variable name stays for diff clarity.
+    private readonly string DefaultAgentId;
 
     public PipeDiscoveryServiceTests()
     {
         _mockPowerShellService = new Mock<IPowerShellService>();
         _service = new PipeDiscoveryService(_mockPowerShellService.Object);
+        DefaultAgentId = ConsoleSessionManager.Instance.AllocateSubAgentId();
     }
 
     #region DetectClosedConsoles Tests

Tests/Unit/Proxy/PowerShellToolsTests.cs

@@ -17,13 +17,23 @@ public class PowerShellToolsTests
 {
     private readonly Mock<IPowerShellService> _mockPowerShellService;
     private readonly Mock<IPipeDiscoveryService> _mockPipeDiscoveryService;
-    private const string TestAgentId = "default";
-    private const string TestPipeName = "PSMCP.1000.default.2000";
+    // Allocate a unique sub-agent id per test instance (xunit creates one per test
+    // method) so concurrent test classes touching the static ConsoleSessionManager.Instance
+    // — which keys all state by agent id — can't trample each other. A previous run hit
+    // a flaky failure on Windows where another suite''s "default" entry had cleared this
+    // class''s active-pipe registration mid-test. Names kept for diff clarity.
+    private readonly string TestAgentId;
+    private readonly string TestPipeName;
 
     public PowerShellToolsTests()
     {
         _mockPowerShellService = new Mock<IPowerShellService>();
         _mockPipeDiscoveryService = new Mock<IPipeDiscoveryService>();
+        TestAgentId = ConsoleSessionManager.Instance.AllocateSubAgentId();
+        // Pipe name format: PSMCP.{proxyPid}.{agentId}.{pwshPid}. Match the agent id
+        // so any code that re-derives agentId from the pipe name (or filters by it)
+        // sees consistent values.
+        TestPipeName = $"PSMCP.1000.{TestAgentId}.2000";
     }
 
     #region GetCurrentLocation Tests