fix(agent99): harden runtime deploy rollback

apps/api/tests/test_agent99_transport_recovery_deploy_contract.py

@@ -164,6 +164,25 @@ def test_agent99_deployer_verifies_promoted_runtime_and_writes_revision() -> Non
         assert f'"{name}"' in bootstrap
 
 
+def test_agent99_deployer_backs_up_manifest_before_runtime_promotion() -> None:
+    deploy = DEPLOY.read_text(encoding="utf-8")
+    promotion = deploy[deploy.index("$configBackedUp = $false") :]
+    promotion = promotion[: promotion.index("$config = Get-Content $ConfigPath")]
+
+    assert promotion.index('Copy-Item -Force $ConfigPath') < promotion.index(
+        "foreach ($name in $runtimeFiles)"
+    )
+    assert promotion.index('Copy-Item -Force $ManifestPath') < promotion.index(
+        "foreach ($name in $runtimeFiles)"
+    )
+    assert 'Restore-Agent99Deployment $promotionRows $configBackedUp $manifestBackedUp' in deploy
+    assert "function Copy-AgentRuntimeFileWithRetry" in deploy
+    assert "MaxAttempts = 20" in deploy
+    assert 'reason = "file_in_use"' in deploy
+    assert "runtimeCopyRetryCount" in deploy
+    assert "Copy-AgentRuntimeFileWithRetry (Join-Path $StageDir $name) $livePath" in deploy
+
+
 def test_agent99_completion_callback_waits_for_durable_same_trace_readback() -> None:
     source = CONTROL.read_text(encoding="utf-8")
     deploy = DEPLOY.read_text(encoding="utf-8")