[SYMPP-BE79] Stop managed backends after final MCP client

plugins/symphony-plus-plus-mcp/scripts/start-sympp-mcp-bridge.js

@@ -614,7 +614,7 @@ function sameRuntimeNodeLeaseExists(runtimeFile, key) {
 function cleanupLastDetach(runtimeFile, key, cleanupScript) {
   if (sameRuntimeNodeLeaseExists(runtimeFile, key)) return;
   const script = cleanupScript || path.join(__dirname, "start-sympp-mcp.ps1");
-  const args = ["-NoProfile", "-NonInteractive", "-ExecutionPolicy", "Bypass", "-File", script, "-CleanupRuntimeKey", key, "-PreserveCurrentArtifactRuntime"];
+  const args = ["-NoProfile", "-NonInteractive", "-ExecutionPolicy", "Bypass", "-File", script, "-CleanupRuntimeKey", key];
   let result = spawnSync("pwsh.exe", args, { stdio: ["ignore", "ignore", "inherit"] });
   if (result.error && result.error.code === "ENOENT") result = spawnSync("powershell.exe", args, { stdio: ["ignore", "ignore", "inherit"] });
   if (result.error || result.status !== 0) diagnostic(`Symphony++ last-detach cleanup failed: ${result.error ? result.error.message : `exit ${result.status}`}`);

plugins/symphony-plus-plus-mcp/scripts/start-sympp-mcp.ps1

@@ -3,7 +3,6 @@ param(
   [switch]$ValidateOnly,
   [switch]$PrepareRuntimeOnly,
   [switch]$CleanupPreparedRuntime,
-  [switch]$PreserveCurrentArtifactRuntime,
   [string]$CleanupRuntimeKey
 )
 
@@ -1304,10 +1303,9 @@ function Test-RuntimeStateExternalLoopback($RuntimeState) {
     [string]$RuntimeState.frontend.status -eq "external_loopback"
 }
 
-function Test-BackendShouldShutdownOnIdle($BackendPlan, $DashboardPlan, [string]$RuntimeMode) {
+function Test-BackendShouldShutdownOnIdle($BackendPlan, $DashboardPlan) {
   return ($BackendPlan.managed -eq $true) -and
-    ($DashboardPlan.managed -ne $true) -and
-    -not ($RuntimeMode -eq "artifact" -and [string]$DashboardPlan.status -eq "artifact_static")
+    ($DashboardPlan.managed -ne $true)
 }
 
 function Test-RuntimeEntryEndpointMatches([string]$Role, $Entry, [string]$Endpoint) {
@@ -1610,7 +1608,7 @@ function Get-ManagedListenerPid([string]$Role, [int]$Port) {
   return $null
 }
 
-function Stop-ManagedServersIfUnused([string]$RuntimeFile, [string]$RuntimeKey, [bool]$PreserveCurrentArtifactRuntime = $false) {
+function Stop-ManagedServersIfUnused([string]$RuntimeFile, [string]$RuntimeKey) {
   $lock = Enter-FileLock (Resolve-StartupLockFile $RuntimeFile) 30
   try {
     $activeLeases = @(Get-ActiveBridgeLeases $RuntimeFile)
@@ -1628,11 +1626,7 @@ function Stop-ManagedServersIfUnused([string]$RuntimeFile, [string]$RuntimeKey,
     if ((Test-ActiveLegacyBridgeLease $activeLeases) -or (Test-ActiveBridgeLeaseForRuntimeKey $activeLeases $RuntimeKey)) {
       return
     }
-    $preserveCurrent = $PreserveCurrentArtifactRuntime -and
-      [string]$state.runtime_kind -eq "artifact" -and
-      [string]$state.runtime_mode -eq "artifact" -and
-      [string]$state.frontend.status -eq "artifact_static"
-    if ([System.StringComparer]::OrdinalIgnoreCase.Equals($stateKey, $RuntimeKey) -and -not $preserveCurrent) {
+    if ([System.StringComparer]::OrdinalIgnoreCase.Equals($stateKey, $RuntimeKey)) {
       [void](Stop-CurrentManagedRuntimeStateEntries $state $activeLeases)
     }
     $supersededStates = Stop-SupersededRuntimeStatesIfUnused $RuntimeFile (Get-SupersededRuntimeStates $state)
@@ -2075,7 +2069,7 @@ function Invoke-WarmAttachFromRuntimeState {
   } finally {
     Remove-BridgeLease $leasePath
     if ($attached) {
-      Stop-ManagedServersIfUnused $RuntimeFile $identity.runtime_key $true
+      Stop-ManagedServersIfUnused $RuntimeFile $identity.runtime_key
     }
   }
 }
@@ -2242,7 +2236,7 @@ if ($Help) {
 }
 
 if (-not [string]::IsNullOrWhiteSpace($CleanupRuntimeKey)) {
-  Stop-ManagedServersIfUnused (Resolve-RuntimeFile) $CleanupRuntimeKey ([bool]$PreserveCurrentArtifactRuntime)
+  Stop-ManagedServersIfUnused (Resolve-RuntimeFile) $CleanupRuntimeKey
   exit 0
 }
 if ($CleanupPreparedRuntime) {
@@ -2549,7 +2543,7 @@ try {
       [void](Initialize-ElixirRuntime $elixirDir $launcher $mix $mise $logDir $elixirSetupTimeout)
     }
     $backendDashboardOrigin = if ($runtimeMode -eq "artifact" -and [string]$dashboardPlan.status -eq "artifact_static") { $null } else { $dashboardPlan.origin }
-    $backendShutdownOnIdle = Test-BackendShouldShutdownOnIdle $backendPlan $dashboardPlan $runtimeMode
+    $backendShutdownOnIdle = Test-BackendShouldShutdownOnIdle $backendPlan $dashboardPlan
     $startingRuntimeRoot = if ($runtimeMode -eq "artifact") { [string]$artifactRuntime.root } else { [string]$repoRoot }
     if ($installedHttpCold) {
       $startingState.runtime_mode = $runtimeMode; $startingState.runtime_kind = $runtimeMode
@@ -2695,5 +2689,5 @@ try {
   Invoke-HttpMcpBridge $backendPlan.mcp_url $bridgeTimeout (New-McpClientLeaseId) $clientHeartbeatInterval
 } finally {
   Remove-BridgeLease $bridgeLeasePath
-  Stop-ManagedServersIfUnused $runtimeFile $runtimeKey $true
+  Stop-ManagedServersIfUnused $runtimeFile $runtimeKey
 }

plugins/symphony-plus-plus-mcp/tests/launcher/cold-start-singleton-smoke.js

@@ -66,6 +66,14 @@ async function freePort() {
   return port;
 }
 
+function portAvailable(port) {
+  return new Promise((resolve) => {
+    const server = net.createServer();
+    server.once("error", () => resolve(false));
+    server.listen(port, "127.0.0.1", () => server.close(() => resolve(true)));
+  });
+}
+
 async function barrierClient() {
   const [, , , barrier, launcher] = process.argv;
   process.stderr.write("BARRIER_READY\n");
@@ -297,21 +305,21 @@ async function runCase(clientCount, shell, mode = "normal") {
     } finally {
       clearTimeout(readyTimeout);
     }
+    const activeBackend = readJson(backendState);
+    const ownersResult = spawnSync(shell, ["-NoProfile", "-NonInteractive", "-Command", "@(Get-NetTCPConnection -LocalPort $env:FIXTURE_PORT -State Listen -ErrorAction Stop | Select-Object -ExpandProperty OwningProcess -Unique) | ConvertTo-Json -Compress"], { env: { ...process.env, FIXTURE_PORT: String(backendPort) }, encoding: "utf8", windowsHide: true });
+    assert.equal(ownersResult.status, 0, ownersResult.stderr);
+    assert.deepEqual([].concat(JSON.parse(ownersResult.stdout.trim())), [activeBackend.pid]);
     for (const client of clients) { try { client.child.stdin.end(); } catch (_) { } }
     const results = await Promise.all(clients.map((client) => client.result));
     const expectedFailures = mode.endsWith("_death") ? 1 : 0;
     assert.equal(results.filter((result) => result.code !== 0).length, expectedFailures, results.map((result) => result.stderr).join("\n"));
     assert.equal(results.filter((result) => result.code === 0).length, clientCount);
     await waitFor(() => readJson(backendState)?.active_leases === 0, "Backend leases did not drain.");
-    const state = readJson(runtimeFile);
     const backend = readJson(backendState);
     backendPid = backend.pid;
-    const ownersResult = spawnSync(shell, ["-NoProfile", "-NonInteractive", "-Command", "@(Get-NetTCPConnection -LocalPort $env:FIXTURE_PORT -State Listen -ErrorAction Stop | Select-Object -ExpandProperty OwningProcess -Unique) | ConvertTo-Json -Compress"], { env: { ...process.env, FIXTURE_PORT: String(backendPort) }, encoding: "utf8", windowsHide: true });
-    assert.equal(ownersResult.status, 0, ownersResult.stderr);
-    const owners = JSON.parse(ownersResult.stdout.trim());
-    assert.deepEqual([].concat(owners), [backendPid]);
+    await waitFor(() => portAvailable(backendPort), "Backend listener did not stop after the final client exited.");
+    const state = await waitFor(() => { const value = readJson(runtimeFile); return value?.backend?.status === "stopped" && value.backend.pid === null && value; }, "Runtime state did not record zero-client backend shutdown.");
     assert.equal(state.publication.status, "ready");
-    assert.equal(state.backend.pid, backendPid);
     assert.equal(backend.starts, 1);
     assert.equal(backend.initialize, clientCount);
     assert.equal(backend.tools_list, clientCount);
@@ -336,7 +344,7 @@ async function runCase(clientCount, shell, mode = "normal") {
     for (const directory of [symppHome, environment.TEMP]) if (fs.existsSync(directory)) for (const entry of fs.readdirSync(directory, { recursive: true })) if (/artifact\.zip\.tmp-|\.extracting-|codex-plugin\.json\.tmp-/.test(String(entry))) leftovers.push(entry);
     assert.deepEqual(leftovers, []);
     assert.ok(percentile(latencies, 0.95) < 60000 && Math.max(...latencies) < 90000);
-    return { mode, shell: path.basename(shell), clients: clientCount, p95_ms: percentile(latencies, 0.95), max_ms: Math.max(...latencies), manifest: channel.counts.manifest_successes, manifest_attempts: channel.counts.manifest_attempts, artifact: channel.counts.archive_successes, artifact_attempts: channel.counts.archive_attempts, preparations: traceCount(traceDir, "artifact_prepare_end"), backends: backend.starts, pids: 1, listeners: 1, initializes: backend.initialize, tools_list: backend.tools_list, lease_peak: backend.lease_peak, leases_after: backend.active_leases, adopted: traceCount(traceDir, "backend_adopted") };
+    return { mode, shell: path.basename(shell), clients: clientCount, p95_ms: percentile(latencies, 0.95), max_ms: Math.max(...latencies), manifest: channel.counts.manifest_successes, manifest_attempts: channel.counts.manifest_attempts, artifact: channel.counts.archive_successes, artifact_attempts: channel.counts.archive_attempts, preparations: traceCount(traceDir, "artifact_prepare_end"), backends: backend.starts, pids: 1, listeners: 0, initializes: backend.initialize, tools_list: backend.tools_list, lease_peak: backend.lease_peak, leases_after: backend.active_leases, adopted: traceCount(traceDir, "backend_adopted") };
   } finally {
     terminateTrees(clients.filter((client) => client.child.exitCode === null).map((client) => client.child.pid));
     if (!backendPid) backendPid = readJson(backendState)?.pid || 0;