diff --git a/benchmarks/server-port/multinode/README.md b/benchmarks/server-port/multinode/README.md
new file mode 100644
index 000000000..a70775f93
--- /dev/null
+++ b/benchmarks/server-port/multinode/README.md
@@ -0,0 +1,84 @@
+# Multi-node kill and restart qualification
+
+This qualifies native multi-node behavior: no lost durable work, no duplicate
+committed outcome, and no stale worker attempt accepted. It runs on each
+required database family while server nodes are killed and restarted, and
+while a worker loses its lease. It is a correctness check, not a capacity
+measurement.
+
+## Topology
+
+[`server-port-multinode.compose.yml`](../../../scripts/perf/server-port-multinode.compose.yml)
+runs these services:
+
+- **Database.** One of MySQL 8.4, MariaDB 10.11, PostgreSQL 17 or SQLite.
+  With SQLite, the three nodes share one database file on one host.
+- **Native nodes.** Three nodes with the same binary and configuration, one
+  CPU and 512 MiB each. All three start together against the empty
+  database, so bootstrap races too.
+- **Balancer.** HAProxy round-robins over the nodes. Health checks every
+  second take a dead node out after two failures. Like a production
+  balancer, it retries a request on another node only when it could not
+  connect, so the request never reached a server. A request a node accepted
+  and then dropped fails back to its client.
+- **Clients.** Two SDK workers and the offered workload, from the
+  [capacity bindings](../../capacity/v1/bindings/php) with the published PHP
+  SDK. They reach the nodes only through the balancer. A worker that exits is
+  restarted, as a supervisor would; `container-states.txt` records each
+  restart. A restart is an SDK finding, not a server failure, but it is
+  reported with the run.
+
+## Procedure
+
+[`run-server-port-multinode.sh`](../../../scripts/perf/run-server-port-multinode.sh)
+`OUTPUT_DIR mysql|mariadb|postgres|sqlite` offers one-activity workflows at
+0.5/s in three 180-second windows. Each window drains for up to 420 s, longer
+than the five-minute activity lease: an activity whose completion a killed node
+dropped is redelivered only when that lease expires. Two
+kinds of chaos run during the windows:
+
+- **Node kills.** Every 15 s, one node in turn is killed with SIGKILL and
+  restarted 4 s later.
+- **Worker pauses.** Every 90 s, one SDK worker is frozen with `docker pause`
+  for the workflow task lease plus 10 s, then resumed. By then the server has
+  given its workflow tasks to the other worker, so its completions are stale.
+
+[`multinode-workload.php`](../../../scripts/perf/multinode-workload.php)
+starts each workflow under its own ID. It retries a start, describe or history
+read that a dying node never answered, and a retried start finds its own run.
+Each window passes only if every planned workflow completed, with:
+
+- its original output;
+- contiguous history sequences;
+- exactly one `WorkflowStarted`, `ActivityScheduled`, `ActivityCompleted` and
+  `WorkflowCompleted`, in that order;
+- an `ActivityCompleted` from the last attempt that started;
+- no other events except `ActivityStarted` and `RepairRequested`. The server
+  records `RepairRequested` when it recovers the expired lease of a worker
+  that died holding a workflow task; the workload counts these recoveries.
+
+Afterwards the database audit must find:
+
+- every run completed;
+- no run with two `WorkflowCompleted` events;
+- no activity with two completed attempts;
+- no duplicate history sequence.
+
+The balancer log counts the stale completions the servers refused (`409`)
+and the requests a killed node never answered (`5xx`). Node logs are checked
+for panics.
+
+```sh
+# The locked SDK and an optimized binary, as the v2 README describes.
+export DW_PORT_SOURCE_ROOT=/abs/source DW_PORT_SDK_ROOT=/abs/sdk DW_PORT_NATIVE_BINARY=/abs/native/server
+for db in mysql mariadb postgres sqlite; do
+  bash scripts/perf/run-server-port-multinode.sh "results/$db" "$db"
+done
+```
+
+`--smoke` runs one 20-second window to check the setup. It is never a
+qualification.
+
+## Results
+
+- [2026-10-20](results-2026-10-20.md): MySQL, MariaDB, PostgreSQL and SQLite passed.
diff --git a/benchmarks/server-port/multinode/results-2026-10-20.md b/benchmarks/server-port/multinode/results-2026-10-20.md
new file mode 100644
index 000000000..794e15716
--- /dev/null
+++ b/benchmarks/server-port/multinode/results-2026-10-20.md
@@ -0,0 +1,121 @@
+# Multi-node results, 2026-10-20
+
+The full schedule passed on MySQL 8.4, MariaDB 10.11, PostgreSQL 17 and
+SQLite. Every one of the 1,080 offered workflows completed exactly once, with
+its original output and an ordered history, while server nodes were killed
+and restarted and a worker was paused past its lease. The database audits
+found no duplicate committed outcome and no duplicate history sequence. No
+native node panicked.
+
+| Database | Workflows verified | Node kills | Worker pauses | Duplicate outcomes | Stale workflow completions refused | Worker exits |
+| --- | --- | --- | --- | --- | --- | --- |
+| MySQL 8.4 | 270 of 270 | 26 | 3 | 0 | 1 | 2 |
+| MariaDB 10.11 | 270 of 270 | 25 | 3 | 0 | 1 | 3 |
+| PostgreSQL 17 | 270 of 270 | 26 | 3 | 0 | 0 | 2 |
+| SQLite | 270 of 270 | 27 | 3 | 0 | 0 | 3 |
+
+Each workflow's activity ran once. No activity completion was lost to a
+killed node, so none waited for the five-minute activity lease.
+
+## Identity
+
+- Harness: `68d78be19` (MariaDB: `eeb510a3a`, which adds its profile), each
+  run from a clean detached checkout.
+- Native binary: an unoptimized dev-profile build of `rust-325-workflow-lease`
+  `ce18934e1`, SHA-256
+  `53d634e8fb7d96cab64d768e01d47db6e8c2f5a634cf0d6e67e6047b95ac03a9`. This
+  checks correctness, not speed.
+- Clients: the capacity bindings' locked PHP SDK 2.0.10. A later run used SDK 2.5.3 (below).
+- Machine: one Intel i5-6500 host with 4 logical CPUs and no other workload.
+- Raw node, balancer and worker logs were inspected and not kept. Each run's
+  summary is in `summary-<database>-2026-10-20.json`.
+
+## Worker exits
+
+Workers exited and were restarted 10 times in all:
+
+- **Native refusal shape (8 exits, all by the paused worker).** After a pause,
+  the worker sent requests for workflow tasks the server had given to the
+  other worker. Native refused the late lease renewals (`task_not_leased`) and
+  completions (`conflicting_completion`) with only a reason and the task
+  fence. Published PHP refuses the same requests with its ownership guard's
+  fields: the task status, and whether the run is closed. A current worker
+  reads those fields to drop a lost claim.
+  [#548](https://github.com/durable-workflow/server/pull/548) makes native
+  return PHP's bodies, with a parity fixture.
+- **SDK 2.0.10 poll (2 exits).** A poll got HAProxy's HTML 503 while a killed
+  node was still marked up. SDK 2.0.10 treats that body as invalid JSON and
+  exits. The SDK has retried polls on that failure since
+  [sdk-php#69](https://github.com/durable-workflow/sdk-php/issues/69).
+
+Current SDKs still exit when the same proxy failure hits a request for a
+task that is already claimed:
+[sdk-php#197](https://github.com/durable-workflow/sdk-php/issues/197).
+
+## Confirmation with the ownership guard
+
+The same schedule ran again with native built from
+[#548](https://github.com/durable-workflow/server/pull/548) (`f43e6fae2`,
+unoptimized dev profile, SHA-256
+`4c19c325cbd175d58d0b2710bb0450241f3760730514788eedf5185bab312e8f`) and the
+harness at `1a8add148` (MariaDB: `eeb510a3a`). Summaries are in
+`summary-guard-<database>-2026-10-20.json`.
+
+| Database | Workflows verified | Node kills | Duplicate outcomes | Worker exits |
+| --- | --- | --- | --- | --- |
+| MySQL 8.4 | 270 of 270 | 27 | 0 | 4 |
+| MariaDB 10.11 | 270 of 270 | 25 | 0 | 3 |
+| PostgreSQL 17 | 270 of 270 | 27 | 0 | 3 |
+| SQLite | 270 of 270 | 27 | 0 | 2 |
+
+No native node panicked. Every late request from the paused worker was now
+refused with PHP's ownership guard body. Eleven exits followed a late lease
+renewal after the run had closed, refused with `run_closed` and
+`can_continue: false`, the body published PHP returns. SDK 2.0.10 has no
+lost-claim handling (the SDK added it in 2.2.6), so it exits on that refusal
+from either server. The twelfth exit was the SDK 2.0.10 poll case above.
+
+## Current SDK
+
+The schedule ran a third time with the published PHP SDK 2.5.3 installed in
+place of the bindings' locked 2.0.10, and native from #548 as above. Summaries
+are in `summary-sdk253-<database>-2026-10-20.json`.
+
+| Database | Workflows verified | Node kills | Duplicate outcomes | Worker exits |
+| --- | --- | --- | --- | --- |
+| MySQL 8.4 | 270 of 270 | 25 | 0 | 0 |
+| MariaDB 10.11 | 270 of 270 | 26 | 0 | 0 |
+| PostgreSQL 17 | 270 of 270 | 24 | 0 | 0 |
+| SQLite | 270 of 270 | 25 | 0 | 0 |
+
+With a current SDK, the workers stayed up through every node kill and pause.
+Across the four runs the paused worker got 7 lost-claim refusals from native
+(`409` on a late lease renewal or completion) and dropped each claim without
+exiting.
+
+An earlier PostgreSQL run with the same SDK had one worker exit. A node was
+killed while answering that worker's lease renewal, and the balancer returned
+502, which the SDK does not retry while a task is claimed
+([sdk-php#197](https://github.com/durable-workflow/sdk-php/issues/197)). The
+exited worker still held its lease. Native recovered the expired lease as PHP
+does, recording `RepairRequested`, and the workflow completed once. The
+workload then accepted only the happy-path events and flagged that history.
+It now accepts and counts the recovery, and the PostgreSQL row above is the
+rerun.
+
+## Concurrent bootstrap
+
+All three nodes of each run start together against the empty database. In a
+later smoke run on MySQL, one node exited with `unsupported_rust_schema`: it
+started while another node was between creating the native marker table and
+recording its marker. MySQL and MariaDB commit DDL on their own, so that state
+is visible. The correction lets the node wait for the bootstrap lock, and its
+kill qualification covers the window.
+
+## Earlier attempt
+
+The first full MySQL run had no balancer retry and no worker restarts. Both
+workers exited on HAProxy 503 pages while killed nodes were still marked up,
+and window 2 completed nothing. That run measured the clients rather than the
+server. It led to the connect-failure retry and the restart policy in the
+current harness.
diff --git a/benchmarks/server-port/multinode/summary-guard-mariadb-2026-10-20.json b/benchmarks/server-port/multinode/summary-guard-mariadb-2026-10-20.json
new file mode 100644
index 000000000..31c1ecae5
--- /dev/null
+++ b/benchmarks/server-port/multinode/summary-guard-mariadb-2026-10-20.json
@@ -0,0 +1,132 @@
+{
+  "identity": {
+    "database": "mariadb",
+    "compose_project": "dw-mn-mariadb-20261020t190725",
+    "source_revision": "eeb510a3a59b18e0ad530e0a837325ac1d84d4fe",
+    "source_modified_files": 0,
+    "native_binary_sha256": "4c19c325cbd175d58d0b2710bb0450241f3760730514788eedf5185bab312e8f",
+    "smoke": false,
+    "schedule": {
+      "rate": 0.5,
+      "offer_seconds": 180,
+      "drain_seconds": 420,
+      "windows": 3,
+      "node_kill_every_seconds": 15,
+      "node_down_seconds": 4,
+      "worker_pause_every_seconds": 90,
+      "worker_pause_seconds": 70,
+      "workflow_task_lease_seconds": 60
+    },
+    "machine": {
+      "kernel": "5.15.0-198-generic",
+      "logical_cpus": 4,
+      "cpu_model": "Intel(R) Core(TM) i5-6500 CPU @ 3.20GHz"
+    }
+  },
+  "windows": [
+    {
+      "sdk_php": "2.0.10",
+      "outcome": "pass",
+      "planned_starts": 90,
+      "accepted_starts": 90,
+      "completed": 90,
+      "verified": 90,
+      "activity_attempts_per_workflow": {
+        "1": 90
+      },
+      "repairs_by_workflow": null,
+      "retries": [],
+      "errors": []
+    },
+    {
+      "sdk_php": "2.0.10",
+      "outcome": "pass",
+      "planned_starts": 90,
+      "accepted_starts": 90,
+      "completed": 90,
+      "verified": 90,
+      "activity_attempts_per_workflow": {
+        "1": 90
+      },
+      "repairs_by_workflow": null,
+      "retries": [],
+      "errors": []
+    },
+    {
+      "sdk_php": "2.0.10",
+      "outcome": "pass",
+      "planned_starts": 90,
+      "accepted_starts": 90,
+      "completed": 90,
+      "verified": 90,
+      "activity_attempts_per_workflow": {
+        "1": 90
+      },
+      "repairs_by_workflow": null,
+      "retries": [],
+      "errors": []
+    }
+  ],
+  "chaos": {
+    "kill": 25,
+    "pause": 3,
+    "start": 25,
+    "unpause": 3
+  },
+  "balancer": {
+    "requests": 3978,
+    "workflow_task_completions_409": 0,
+    "activity_task_completions_409": 0,
+    "responses_5xx": 0
+  },
+  "database_audit": {
+    "runs completed": 270,
+    "tasks activity completed": 270,
+    "tasks workflow completed": 540,
+    "attempts completed": 270,
+    "duplicate_workflow_completions": 0,
+    "duplicate_activity_completions": 0,
+    "duplicate_history_sequences": 0
+  },
+  "containers": {
+    "lb": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "mariadb": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "native-1": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "native-2": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "native-3": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "sdk-worker-1": {
+      "restarts": 3,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "sdk-worker-2": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    }
+  },
+  "native_panics": 0,
+  "sdk_worker_exits": {
+    "sdk-worker-1: Uncaught DurableWorkflow\\Exception\\TransportException: ": 3
+  }
+}
diff --git a/benchmarks/server-port/multinode/summary-guard-mysql-2026-10-20.json b/benchmarks/server-port/multinode/summary-guard-mysql-2026-10-20.json
new file mode 100644
index 000000000..37adf4c45
--- /dev/null
+++ b/benchmarks/server-port/multinode/summary-guard-mysql-2026-10-20.json
@@ -0,0 +1,137 @@
+{
+  "identity": {
+    "database": "mysql",
+    "compose_project": "dw-mn-mysql-20261020t182603",
+    "source_revision": "1a8add148c293f72243b9dbbe44845f0675d93f9",
+    "source_modified_files": 0,
+    "native_binary_sha256": "4c19c325cbd175d58d0b2710bb0450241f3760730514788eedf5185bab312e8f",
+    "smoke": false,
+    "schedule": {
+      "rate": 0.5,
+      "offer_seconds": 180,
+      "drain_seconds": 420,
+      "windows": 3,
+      "node_kill_every_seconds": 15,
+      "node_down_seconds": 4,
+      "worker_pause_every_seconds": 90,
+      "worker_pause_seconds": 70,
+      "workflow_task_lease_seconds": 60
+    },
+    "machine": {
+      "kernel": "5.15.0-198-generic",
+      "logical_cpus": 4,
+      "cpu_model": "Intel(R) Core(TM) i5-6500 CPU @ 3.20GHz"
+    }
+  },
+  "windows": [
+    {
+      "sdk_php": "2.0.10",
+      "outcome": "pass",
+      "planned_starts": 90,
+      "accepted_starts": 90,
+      "completed": 90,
+      "verified": 90,
+      "activity_attempts_per_workflow": {
+        "1": 90
+      },
+      "repairs_by_workflow": null,
+      "retries": [],
+      "errors": []
+    },
+    {
+      "sdk_php": "2.0.10",
+      "outcome": "pass",
+      "planned_starts": 90,
+      "accepted_starts": 90,
+      "completed": 90,
+      "verified": 90,
+      "activity_attempts_per_workflow": {
+        "1": 90
+      },
+      "repairs_by_workflow": null,
+      "retries": [],
+      "errors": []
+    },
+    {
+      "sdk_php": "2.0.10",
+      "outcome": "pass",
+      "planned_starts": 90,
+      "accepted_starts": 90,
+      "completed": 90,
+      "verified": 90,
+      "activity_attempts_per_workflow": {
+        "1": 90
+      },
+      "repairs_by_workflow": null,
+      "retries": {
+        "start": {
+          "http_0": 1
+        }
+      },
+      "errors": []
+    }
+  ],
+  "chaos": {
+    "kill": 27,
+    "pause": 3,
+    "start": 27,
+    "unpause": 3
+  },
+  "balancer": {
+    "requests": 4009,
+    "workflow_task_completions_409": 0,
+    "activity_task_completions_409": 0,
+    "responses_5xx": 2
+  },
+  "database_audit": {
+    "runs completed": 270,
+    "tasks workflow completed": 540,
+    "tasks activity completed": 270,
+    "attempts completed": 270,
+    "duplicate_workflow_completions": 0,
+    "duplicate_activity_completions": 0,
+    "duplicate_history_sequences": 0
+  },
+  "containers": {
+    "lb": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "mysql": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "native-1": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "native-2": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "native-3": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "sdk-worker-1": {
+      "restarts": 4,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "sdk-worker-2": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    }
+  },
+  "native_panics": 0,
+  "sdk_worker_exits": {
+    "sdk-worker-1: Uncaught DurableWorkflow\\Exception\\TransportException: ": 3,
+    "sdk-worker-1: Uncaught JsonException: ": 1
+  }
+}
diff --git a/benchmarks/server-port/multinode/summary-guard-postgres-2026-10-20.json b/benchmarks/server-port/multinode/summary-guard-postgres-2026-10-20.json
new file mode 100644
index 000000000..95431d0e1
--- /dev/null
+++ b/benchmarks/server-port/multinode/summary-guard-postgres-2026-10-20.json
@@ -0,0 +1,132 @@
+{
+  "identity": {
+    "database": "postgres",
+    "compose_project": "dw-mn-postgres-20261020t183624",
+    "source_revision": "1a8add148c293f72243b9dbbe44845f0675d93f9",
+    "source_modified_files": 0,
+    "native_binary_sha256": "4c19c325cbd175d58d0b2710bb0450241f3760730514788eedf5185bab312e8f",
+    "smoke": false,
+    "schedule": {
+      "rate": 0.5,
+      "offer_seconds": 180,
+      "drain_seconds": 420,
+      "windows": 3,
+      "node_kill_every_seconds": 15,
+      "node_down_seconds": 4,
+      "worker_pause_every_seconds": 90,
+      "worker_pause_seconds": 70,
+      "workflow_task_lease_seconds": 60
+    },
+    "machine": {
+      "kernel": "5.15.0-198-generic",
+      "logical_cpus": 4,
+      "cpu_model": "Intel(R) Core(TM) i5-6500 CPU @ 3.20GHz"
+    }
+  },
+  "windows": [
+    {
+      "sdk_php": "2.0.10",
+      "outcome": "pass",
+      "planned_starts": 90,
+      "accepted_starts": 90,
+      "completed": 90,
+      "verified": 90,
+      "activity_attempts_per_workflow": {
+        "1": 90
+      },
+      "repairs_by_workflow": null,
+      "retries": [],
+      "errors": []
+    },
+    {
+      "sdk_php": "2.0.10",
+      "outcome": "pass",
+      "planned_starts": 90,
+      "accepted_starts": 90,
+      "completed": 90,
+      "verified": 90,
+      "activity_attempts_per_workflow": {
+        "1": 90
+      },
+      "repairs_by_workflow": null,
+      "retries": [],
+      "errors": []
+    },
+    {
+      "sdk_php": "2.0.10",
+      "outcome": "pass",
+      "planned_starts": 90,
+      "accepted_starts": 90,
+      "completed": 90,
+      "verified": 90,
+      "activity_attempts_per_workflow": {
+        "1": 90
+      },
+      "repairs_by_workflow": null,
+      "retries": [],
+      "errors": []
+    }
+  ],
+  "chaos": {
+    "kill": 27,
+    "pause": 3,
+    "start": 27,
+    "unpause": 3
+  },
+  "balancer": {
+    "requests": 3983,
+    "workflow_task_completions_409": 0,
+    "activity_task_completions_409": 0,
+    "responses_5xx": 0
+  },
+  "database_audit": {
+    "runs completed": 270,
+    "tasks workflow completed": 540,
+    "tasks activity completed": 270,
+    "attempts completed": 270,
+    "duplicate_workflow_completions": 0,
+    "duplicate_activity_completions": 0,
+    "duplicate_history_sequences": 0
+  },
+  "containers": {
+    "lb": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "native-1": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "native-2": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "native-3": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "postgres": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "sdk-worker-1": {
+      "restarts": 3,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "sdk-worker-2": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    }
+  },
+  "native_panics": 0,
+  "sdk_worker_exits": {
+    "sdk-worker-1: Uncaught DurableWorkflow\\Exception\\TransportException: ": 3
+  }
+}
diff --git a/benchmarks/server-port/multinode/summary-guard-sqlite-2026-10-20.json b/benchmarks/server-port/multinode/summary-guard-sqlite-2026-10-20.json
new file mode 100644
index 000000000..36cc13ed6
--- /dev/null
+++ b/benchmarks/server-port/multinode/summary-guard-sqlite-2026-10-20.json
@@ -0,0 +1,127 @@
+{
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+}
diff --git a/benchmarks/server-port/multinode/summary-mariadb-2026-10-20.json b/benchmarks/server-port/multinode/summary-mariadb-2026-10-20.json
new file mode 100644
index 000000000..75959bb5f
--- /dev/null
+++ b/benchmarks/server-port/multinode/summary-mariadb-2026-10-20.json
@@ -0,0 +1,134 @@
+{
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+      "cpu_model": "Intel(R) Core(TM) i5-6500 CPU @ 3.20GHz"
+    }
+  },
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+    "sdk-worker-2: Uncaught JsonException: ": 1
+  }
+}
diff --git a/benchmarks/server-port/multinode/summary-mysql-2026-10-20.json b/benchmarks/server-port/multinode/summary-mysql-2026-10-20.json
new file mode 100644
index 000000000..f65b4dad7
--- /dev/null
+++ b/benchmarks/server-port/multinode/summary-mysql-2026-10-20.json
@@ -0,0 +1,133 @@
+{
+  "identity": {
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+}
diff --git a/benchmarks/server-port/multinode/summary-postgres-2026-10-20.json b/benchmarks/server-port/multinode/summary-postgres-2026-10-20.json
new file mode 100644
index 000000000..f09a174d3
--- /dev/null
+++ b/benchmarks/server-port/multinode/summary-postgres-2026-10-20.json
@@ -0,0 +1,132 @@
+{
+  "identity": {
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+    }
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+}
diff --git a/benchmarks/server-port/multinode/summary-sdk253-mariadb-2026-10-20.json b/benchmarks/server-port/multinode/summary-sdk253-mariadb-2026-10-20.json
new file mode 100644
index 000000000..823f2ae1c
--- /dev/null
+++ b/benchmarks/server-port/multinode/summary-sdk253-mariadb-2026-10-20.json
@@ -0,0 +1,130 @@
+{
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+}
diff --git a/benchmarks/server-port/multinode/summary-sdk253-mysql-2026-10-20.json b/benchmarks/server-port/multinode/summary-sdk253-mysql-2026-10-20.json
new file mode 100644
index 000000000..9bd30d9ac
--- /dev/null
+++ b/benchmarks/server-port/multinode/summary-sdk253-mysql-2026-10-20.json
@@ -0,0 +1,130 @@
+{
+  "identity": {
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+    },
+    "machine": {
+      "kernel": "5.15.0-198-generic",
+      "logical_cpus": 4,
+      "cpu_model": "Intel(R) Core(TM) i5-6500 CPU @ 3.20GHz"
+    }
+  },
+  "windows": [
+    {
+      "sdk_php": "2.5.3",
+      "outcome": "pass",
+      "planned_starts": 90,
+      "accepted_starts": 90,
+      "completed": 90,
+      "verified": 90,
+      "activity_attempts_per_workflow": {
+        "1": 90
+      },
+      "repairs_by_workflow": null,
+      "retries": [],
+      "errors": []
+    },
+    {
+      "sdk_php": "2.5.3",
+      "outcome": "pass",
+      "planned_starts": 90,
+      "accepted_starts": 90,
+      "completed": 90,
+      "verified": 90,
+      "activity_attempts_per_workflow": {
+        "1": 90
+      },
+      "repairs_by_workflow": null,
+      "retries": [],
+      "errors": []
+    },
+    {
+      "sdk_php": "2.5.3",
+      "outcome": "pass",
+      "planned_starts": 90,
+      "accepted_starts": 90,
+      "completed": 90,
+      "verified": 90,
+      "activity_attempts_per_workflow": {
+        "1": 90
+      },
+      "repairs_by_workflow": null,
+      "retries": [],
+      "errors": []
+    }
+  ],
+  "chaos": {
+    "kill": 25,
+    "pause": 3,
+    "start": 25,
+    "unpause": 3
+  },
+  "balancer": {
+    "requests": 4263,
+    "workflow_task_completions_409": 0,
+    "activity_task_completions_409": 0,
+    "responses_5xx": 1
+  },
+  "database_audit": {
+    "runs completed": 270,
+    "tasks workflow completed": 540,
+    "tasks activity completed": 270,
+    "attempts completed": 270,
+    "duplicate_workflow_completions": 0,
+    "duplicate_activity_completions": 0,
+    "duplicate_history_sequences": 0
+  },
+  "containers": {
+    "lb": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "mysql": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "native-1": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "native-2": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "native-3": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "sdk-worker-1": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "sdk-worker-2": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    }
+  },
+  "native_panics": 0,
+  "sdk_worker_exits": {}
+}
diff --git a/benchmarks/server-port/multinode/summary-sdk253-postgres-2026-10-20.json b/benchmarks/server-port/multinode/summary-sdk253-postgres-2026-10-20.json
new file mode 100644
index 000000000..f47975969
--- /dev/null
+++ b/benchmarks/server-port/multinode/summary-sdk253-postgres-2026-10-20.json
@@ -0,0 +1,130 @@
+{
+  "identity": {
+    "database": "postgres",
+    "compose_project": "dw-mn-postgres-20261020t204232",
+    "source_revision": "6b676949af70caf4f5b685d0466ccf278c1577c0",
+    "source_modified_files": 0,
+    "native_binary_sha256": "4c19c325cbd175d58d0b2710bb0450241f3760730514788eedf5185bab312e8f",
+    "smoke": false,
+    "schedule": {
+      "rate": 0.5,
+      "offer_seconds": 180,
+      "drain_seconds": 420,
+      "windows": 3,
+      "node_kill_every_seconds": 15,
+      "node_down_seconds": 4,
+      "worker_pause_every_seconds": 90,
+      "worker_pause_seconds": 70,
+      "workflow_task_lease_seconds": 60
+    },
+    "machine": {
+      "kernel": "5.15.0-198-generic",
+      "logical_cpus": 4,
+      "cpu_model": "Intel(R) Core(TM) i5-6500 CPU @ 3.20GHz"
+    }
+  },
+  "windows": [
+    {
+      "sdk_php": "2.5.3",
+      "outcome": "pass",
+      "planned_starts": 90,
+      "accepted_starts": 90,
+      "completed": 90,
+      "verified": 90,
+      "activity_attempts_per_workflow": {
+        "1": 90
+      },
+      "repairs_by_workflow": {},
+      "retries": [],
+      "errors": []
+    },
+    {
+      "sdk_php": "2.5.3",
+      "outcome": "pass",
+      "planned_starts": 90,
+      "accepted_starts": 90,
+      "completed": 90,
+      "verified": 90,
+      "activity_attempts_per_workflow": {
+        "1": 90
+      },
+      "repairs_by_workflow": {},
+      "retries": [],
+      "errors": []
+    },
+    {
+      "sdk_php": "2.5.3",
+      "outcome": "pass",
+      "planned_starts": 90,
+      "accepted_starts": 90,
+      "completed": 90,
+      "verified": 90,
+      "activity_attempts_per_workflow": {
+        "1": 90
+      },
+      "repairs_by_workflow": {},
+      "retries": [],
+      "errors": []
+    }
+  ],
+  "chaos": {
+    "kill": 24,
+    "pause": 3,
+    "start": 24,
+    "unpause": 3
+  },
+  "balancer": {
+    "requests": 4262,
+    "workflow_task_completions_409": 0,
+    "activity_task_completions_409": 0,
+    "responses_5xx": 0
+  },
+  "database_audit": {
+    "runs completed": 270,
+    "tasks activity completed": 270,
+    "tasks workflow completed": 540,
+    "attempts completed": 270,
+    "duplicate_workflow_completions": 0,
+    "duplicate_activity_completions": 0,
+    "duplicate_history_sequences": 0
+  },
+  "containers": {
+    "lb": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "native-1": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "native-2": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "native-3": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "postgres": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "sdk-worker-1": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "sdk-worker-2": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    }
+  },
+  "native_panics": 0,
+  "sdk_worker_exits": {}
+}
diff --git a/benchmarks/server-port/multinode/summary-sdk253-sqlite-2026-10-20.json b/benchmarks/server-port/multinode/summary-sdk253-sqlite-2026-10-20.json
new file mode 100644
index 000000000..de431eea5
--- /dev/null
+++ b/benchmarks/server-port/multinode/summary-sdk253-sqlite-2026-10-20.json
@@ -0,0 +1,125 @@
+{
+  "identity": {
+    "database": "sqlite",
+    "compose_project": "dw-mn-sqlite-20261020t202729",
+    "source_revision": "eeb510a3a59b18e0ad530e0a837325ac1d84d4fe",
+    "source_modified_files": 0,
+    "native_binary_sha256": "4c19c325cbd175d58d0b2710bb0450241f3760730514788eedf5185bab312e8f",
+    "smoke": false,
+    "schedule": {
+      "rate": 0.5,
+      "offer_seconds": 180,
+      "drain_seconds": 420,
+      "windows": 3,
+      "node_kill_every_seconds": 15,
+      "node_down_seconds": 4,
+      "worker_pause_every_seconds": 90,
+      "worker_pause_seconds": 70,
+      "workflow_task_lease_seconds": 60
+    },
+    "machine": {
+      "kernel": "5.15.0-198-generic",
+      "logical_cpus": 4,
+      "cpu_model": "Intel(R) Core(TM) i5-6500 CPU @ 3.20GHz"
+    }
+  },
+  "windows": [
+    {
+      "sdk_php": "2.5.3",
+      "outcome": "pass",
+      "planned_starts": 90,
+      "accepted_starts": 90,
+      "completed": 90,
+      "verified": 90,
+      "activity_attempts_per_workflow": {
+        "1": 90
+      },
+      "repairs_by_workflow": null,
+      "retries": [],
+      "errors": []
+    },
+    {
+      "sdk_php": "2.5.3",
+      "outcome": "pass",
+      "planned_starts": 90,
+      "accepted_starts": 90,
+      "completed": 90,
+      "verified": 90,
+      "activity_attempts_per_workflow": {
+        "1": 90
+      },
+      "repairs_by_workflow": null,
+      "retries": [],
+      "errors": []
+    },
+    {
+      "sdk_php": "2.5.3",
+      "outcome": "pass",
+      "planned_starts": 90,
+      "accepted_starts": 90,
+      "completed": 90,
+      "verified": 90,
+      "activity_attempts_per_workflow": {
+        "1": 90
+      },
+      "repairs_by_workflow": null,
+      "retries": [],
+      "errors": []
+    }
+  ],
+  "chaos": {
+    "kill": 25,
+    "pause": 3,
+    "start": 25,
+    "unpause": 3
+  },
+  "balancer": {
+    "requests": 4351,
+    "workflow_task_completions_409": 0,
+    "activity_task_completions_409": 0,
+    "responses_5xx": 0
+  },
+  "database_audit": {
+    "runs completed": 270,
+    "tasks activity completed": 270,
+    "tasks workflow completed": 540,
+    "attempts completed": 270,
+    "duplicate_workflow_completions": 0,
+    "duplicate_activity_completions": 0,
+    "duplicate_history_sequences": 0
+  },
+  "containers": {
+    "lb": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "native-1": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "native-2": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "native-3": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "sdk-worker-1": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "sdk-worker-2": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    }
+  },
+  "native_panics": 0,
+  "sdk_worker_exits": {}
+}
diff --git a/benchmarks/server-port/multinode/summary-sqlite-2026-10-20.json b/benchmarks/server-port/multinode/summary-sqlite-2026-10-20.json
new file mode 100644
index 000000000..a22e141b2
--- /dev/null
+++ b/benchmarks/server-port/multinode/summary-sqlite-2026-10-20.json
@@ -0,0 +1,127 @@
+{
+  "identity": {
+    "database": "sqlite",
+    "compose_project": "dw-mn-sqlite-20261020t172123",
+    "source_revision": "68d78be19c445b22e4cd95a404c50c4f3f52f271",
+    "source_modified_files": 0,
+    "native_binary_sha256": "53d634e8fb7d96cab64d768e01d47db6e8c2f5a634cf0d6e67e6047b95ac03a9",
+    "smoke": false,
+    "schedule": {
+      "rate": 0.5,
+      "offer_seconds": 180,
+      "drain_seconds": 420,
+      "windows": 3,
+      "node_kill_every_seconds": 15,
+      "node_down_seconds": 4,
+      "worker_pause_every_seconds": 90,
+      "worker_pause_seconds": 70,
+      "workflow_task_lease_seconds": 60
+    },
+    "machine": {
+      "kernel": "5.15.0-198-generic",
+      "logical_cpus": 4,
+      "cpu_model": "Intel(R) Core(TM) i5-6500 CPU @ 3.20GHz"
+    }
+  },
+  "windows": [
+    {
+      "sdk_php": "2.0.10",
+      "outcome": "pass",
+      "planned_starts": 90,
+      "accepted_starts": 90,
+      "completed": 90,
+      "verified": 90,
+      "activity_attempts_per_workflow": {
+        "1": 90
+      },
+      "repairs_by_workflow": null,
+      "retries": [],
+      "errors": []
+    },
+    {
+      "sdk_php": "2.0.10",
+      "outcome": "pass",
+      "planned_starts": 90,
+      "accepted_starts": 90,
+      "completed": 90,
+      "verified": 90,
+      "activity_attempts_per_workflow": {
+        "1": 90
+      },
+      "repairs_by_workflow": null,
+      "retries": [],
+      "errors": []
+    },
+    {
+      "sdk_php": "2.0.10",
+      "outcome": "pass",
+      "planned_starts": 90,
+      "accepted_starts": 90,
+      "completed": 90,
+      "verified": 90,
+      "activity_attempts_per_workflow": {
+        "1": 90
+      },
+      "repairs_by_workflow": null,
+      "retries": [],
+      "errors": []
+    }
+  ],
+  "chaos": {
+    "kill": 27,
+    "pause": 3,
+    "start": 27,
+    "unpause": 3
+  },
+  "balancer": {
+    "requests": 3990,
+    "workflow_task_completions_409": 0,
+    "activity_task_completions_409": 0,
+    "responses_5xx": 0
+  },
+  "database_audit": {
+    "runs completed": 270,
+    "tasks activity completed": 270,
+    "tasks workflow completed": 540,
+    "attempts completed": 270,
+    "duplicate_workflow_completions": 0,
+    "duplicate_activity_completions": 0,
+    "duplicate_history_sequences": 0
+  },
+  "containers": {
+    "lb": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "native-1": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "native-2": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "native-3": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "sdk-worker-1": {
+      "restarts": 3,
+      "oom_killed": false,
+      "exit_code": 0
+    },
+    "sdk-worker-2": {
+      "restarts": 0,
+      "oom_killed": false,
+      "exit_code": 0
+    }
+  },
+  "native_panics": 0,
+  "sdk_worker_exits": {
+    "sdk-worker-1: Uncaught DurableWorkflow\\Exception\\TransportException: task_not_leased": 3
+  }
+}
diff --git a/scripts/perf/multinode-haproxy.cfg b/scripts/perf/multinode-haproxy.cfg
new file mode 100644
index 000000000..a783664d5
--- /dev/null
+++ b/scripts/perf/multinode-haproxy.cfg
@@ -0,0 +1,38 @@
+# Round-robin over the three native nodes. A node that stops answering health
+# checks is taken out within two seconds and returns when it answers again.
+# A request that could not connect to a node never reached it, so it is
+# retried on another node, as a production balancer does. A request a node
+# accepted and then dropped when it was killed is never retried here: it fails
+# back to its client, which owns that retry.
+global
+    log stdout format raw local0 info
+
+resolvers docker
+    nameserver dns 127.0.0.11:53
+    hold valid 1s
+
+defaults
+    mode http
+    log global
+    # One line per request: the evidence that stale completions were refused.
+    option httplog
+    timeout connect 2s
+    # Long polls hold for up to 30 seconds.
+    timeout client 75s
+    timeout server 75s
+    # The default retry-on is conn-failure only.
+    retries 3
+    option redispatch 1
+
+frontend api
+    bind :8080
+    default_backend natives
+
+backend natives
+    balance roundrobin
+    option httpchk GET /api/health
+    http-check expect status 200
+    default-server inter 1s fall 2 rise 2 resolvers docker init-addr none
+    server native-1 native-1:8080 check
+    server native-2 native-2:8080 check
+    server native-3 native-3:8080 check
diff --git a/scripts/perf/multinode-workload.php b/scripts/perf/multinode-workload.php
new file mode 100644
index 000000000..9829e7631
--- /dev/null
+++ b/scripts/perf/multinode-workload.php
@@ -0,0 +1,189 @@
+<?php
+
+declare(strict_types=1);
+
+// Offered one-activity workflows through a load balancer while server nodes
+// are killed and restarted. A request a dying node never answered is retried
+// under the same workflow ID, so no start is lost and none is duplicated.
+// Afterwards every workflow must have completed once, with its original
+// output and an ordered history: one completion, and an activity completed
+// by the last attempt that started it.
+//
+//   multinode-workload.php <0.1-5 starts/sec> <5-600 offer seconds> <10-600 drain seconds> <workflow-id prefix>
+use Composer\InstalledVersions;
+use DurableWorkflow\Exception\ServerException;
+
+require_once dirname(__DIR__, 2).'/benchmarks/capacity/v1/bindings/php/capacity_adapter.php';
+capacityAutoload();
+
+// A completed workflow whose output or history breaks the qualification.
+final class MultinodeVerificationFailure extends RuntimeException
+{
+}
+
+$rate = filter_var($argv[1] ?? null, FILTER_VALIDATE_FLOAT, ['options' => ['min_range' => 0.1, 'max_range' => 5.0]]);
+$duration = filter_var($argv[2] ?? null, FILTER_VALIDATE_INT, ['options' => ['min_range' => 5, 'max_range' => 600]]);
+$drain = filter_var($argv[3] ?? null, FILTER_VALIDATE_INT, ['options' => ['min_range' => 10, 'max_range' => 600]]);
+$prefix = $argv[4] ?? '';
+if ($rate === false || $duration === false || $drain === false || ! preg_match('/\A[a-z0-9-]{1,40}\z/', $prefix)) {
+    throw new InvalidArgumentException('Usage: multinode-workload.php <0.1-5 starts/sec> <5-600 offer seconds> <10-600 drain seconds> <prefix>.');
+}
+$queue = capacityEnvironment('DURABLE_WORKFLOW_TASK_QUEUE');
+if ($queue === null) {
+    throw new InvalidArgumentException('Set DURABLE_WORKFLOW_TASK_QUEUE.');
+}
+$client = capacityClient(false);
+$blob = str_repeat('m', 1024);
+$input = ['blob' => $blob, 'payload_contract' => ['workflow_input_bytes' => 1024, 'workflow_result_bytes' => 1024,
+    'activity_input_bytes' => 1024, 'activity_result_bytes' => 1024, 'signal_bytes' => 0]];
+$retries = [];
+$errors = [];
+
+// Only a server's 4xx answer is final. A transport failure, a 5xx answer, or
+// a reply cut off when its node was killed (even under a 2xx status) is
+// retried; every retried request is safe to repeat under its workflow ID.
+$retrying = static function (string $what, callable $call, float $until) use (&$retries) {
+    $delay = 0.2;
+    while (true) {
+        try {
+            return $call();
+        } catch (ServerException $error) {
+            if ($error->status >= 400 && $error->status < 500 || microtime(true) >= $until) {
+                throw $error;
+            }
+            $class = 'http_'.$error->status;
+        } catch (Throwable $error) {
+            if (microtime(true) >= $until) {
+                throw $error;
+            }
+            $class = get_class($error);
+        }
+        $retries[$what][$class] = ($retries[$what][$class] ?? 0) + 1;
+        usleep((int) ($delay * 1_000_000));
+        $delay = min(2.0, $delay * 2);
+    }
+};
+
+$planned = (int) ceil($rate * $duration);
+$began = microtime(true);
+$offerEnds = $began + $duration;
+$deadline = $offerEnds + $drain;
+$ids = [];
+$started = [];
+for ($n = 0; $n < $planned; $n++) {
+    $due = $began + $n / $rate;
+    if (($wait = $due - microtime(true)) > 0) {
+        usleep((int) ($wait * 1_000_000));
+    }
+    $id = sprintf('%s-%04d', $prefix, $n);
+    $ids[] = $id;
+    try {
+        $retrying('start', static function () use ($client, $id, $queue, $input): void {
+            try {
+                $client->startWorkflow('capacity.v1.one_activity', $id, $queue, [$input]);
+            } catch (ServerException $error) {
+                // A retried start whose first attempt was accepted finds its own run.
+                if ($error->status !== 409) {
+                    throw $error;
+                }
+                $existing = $client->describeWorkflow($id);
+                if ($existing->workflowType !== 'capacity.v1.one_activity') {
+                    throw $error;
+                }
+            }
+        }, $due + 60);
+        $started[$id] = microtime(true);
+    } catch (Throwable $error) {
+        $errors[] = $id.': start: '.$error->getMessage();
+    }
+}
+
+$completed = [];
+$pending = array_keys($started);
+while ($pending !== [] && microtime(true) < $deadline) {
+    $id = array_shift($pending);
+    try {
+        $execution = $retrying('describe', static fn () => $client->describeWorkflow($id), $deadline);
+        if ($execution->status === 'completed') {
+            $completed[$id] = $execution;
+        } elseif ($execution->isTerminal === true) {
+            $errors[] = $id.': terminal status '.$execution->status;
+        } else {
+            $pending[] = $id;
+            usleep(20_000);
+        }
+    } catch (Throwable $error) {
+        $pending[] = $id;
+    }
+}
+
+$verified = 0;
+$attemptsByWorkflow = [];
+$repairedWorkflows = [];
+foreach ($completed as $id => $execution) {
+    try {
+        if ($execution->output !== $blob) {
+            throw new MultinodeVerificationFailure('output differs');
+        }
+        $history = $retrying('history', static fn () => $client->workflowHistory($id, $execution->runId), microtime(true) + 60);
+        $events = $history['events'] ?? [];
+        $sequences = array_column($events, 'sequence');
+        if ($sequences !== range(1, count($events))) {
+            throw new MultinodeVerificationFailure('history sequences are not contiguous');
+        }
+        $types = array_column($events, 'event_type');
+        $counts = array_count_values($types);
+        // A worker that dies holding a workflow task lease leaves the task to
+        // the server's expired-lease recovery, which records RepairRequested.
+        $allowed = ['StartAccepted', 'WorkflowStarted', 'ActivityScheduled', 'ActivityStarted', 'ActivityCompleted',
+            'WorkflowCompleted', 'RepairRequested'];
+        if (($unexpected = array_diff(array_keys($counts), $allowed)) !== []) {
+            throw new MultinodeVerificationFailure('unexpected events '.implode(',', $unexpected));
+        }
+        foreach (['WorkflowStarted', 'ActivityScheduled', 'ActivityCompleted', 'WorkflowCompleted'] as $once) {
+            if (($counts[$once] ?? 0) !== 1) {
+                throw new MultinodeVerificationFailure($once.' recorded '.($counts[$once] ?? 0).' times');
+            }
+        }
+        $starts = array_values(array_filter($events, static fn (array $e): bool => $e['event_type'] === 'ActivityStarted'));
+        $completion = array_values(array_filter($events, static fn (array $e): bool => $e['event_type'] === 'ActivityCompleted'))[0];
+        if ($starts === [] || end($starts)['payload']['activity_attempt_id'] !== $completion['payload']['activity_attempt_id']) {
+            throw new MultinodeVerificationFailure('the completed activity attempt is not the last one started');
+        }
+        $order = array_values(array_intersect($types, ['WorkflowStarted', 'ActivityScheduled', 'ActivityCompleted', 'WorkflowCompleted']));
+        if ($order !== ['WorkflowStarted', 'ActivityScheduled', 'ActivityCompleted', 'WorkflowCompleted']) {
+            throw new MultinodeVerificationFailure('events out of order');
+        }
+        $attemptsByWorkflow[count($starts)] = ($attemptsByWorkflow[count($starts)] ?? 0) + 1;
+        if (($counts['RepairRequested'] ?? 0) > 0) {
+            $repairedWorkflows[$id] = $counts['RepairRequested'];
+        }
+        $verified++;
+    } catch (Throwable $error) {
+        $errors[] = $id.': verification: '.$error->getMessage();
+    }
+}
+foreach ($pending as $id) {
+    $errors[] = $id.': not completed by the drain deadline';
+}
+
+echo json_encode([
+    'probe' => 'multinode-offered-one-activity',
+    'sdk_php' => InstalledVersions::getPrettyVersion('durable-workflow/sdk'),
+    'prefix' => $prefix,
+    'offered_rate_per_second' => $rate,
+    'offer_seconds' => $duration,
+    'drain_limit_seconds' => $drain,
+    'started_at_unix_seconds' => $began,
+    'finished_at_unix_seconds' => microtime(true),
+    'planned_starts' => $planned,
+    'accepted_starts' => count($started),
+    'completed' => count($completed),
+    'verified' => $verified,
+    'activity_attempts_per_workflow' => $attemptsByWorkflow,
+    'repairs_by_workflow' => (object) $repairedWorkflows,
+    'retries' => $retries,
+    'errors' => $errors,
+    'outcome' => $errors === [] && $verified === $planned ? 'pass' : 'fail',
+], JSON_PRETTY_PRINT)."\n";
+exit($errors === [] && $verified === $planned ? 0 : 1);
diff --git a/scripts/perf/run-server-port-multinode.sh b/scripts/perf/run-server-port-multinode.sh
new file mode 100755
index 000000000..93fd36c4a
--- /dev/null
+++ b/scripts/perf/run-server-port-multinode.sh
@@ -0,0 +1,201 @@
+#!/usr/bin/env bash
+# Multi-node native kill/restart qualification on one database family.
+#
+#   run-server-port-multinode.sh OUTPUT_DIR mysql|mariadb|postgres|sqlite [--smoke]
+#
+# Three native nodes share one database behind HAProxy. Two published-SDK
+# workers and the offered workload reach them only through the balancer.
+# While work is offered, one node at a time is killed with SIGKILL and
+# restarted, and one SDK worker is paused for longer than a workflow task
+# lease, so its late completions are stale. Every workflow must complete
+# once with its original output and an ordered history, and the database
+# audit must find no duplicate committed outcome.
+#
+# Set DW_PORT_SOURCE_ROOT, DW_PORT_SDK_ROOT and DW_PORT_NATIVE_BINARY as the
+# server-port v2 README describes. Run on a host with no other workload.
+set -Eeuo pipefail
+
+out=$1
+db=$2
+mode=${3:-}
+case "$db" in mysql|mariadb|postgres|sqlite) ;; *) echo "Choose mysql, mariadb, postgres or sqlite." >&2; exit 2 ;; esac
+case "$mode" in ""|--smoke) ;; *) echo "Unknown option $mode." >&2; exit 2 ;; esac
+: "${DW_PORT_SOURCE_ROOT:?Set the absolute source directory}"
+: "${DW_PORT_SDK_ROOT:?Set the normally installed SDK directory}"
+: "${DW_PORT_NATIVE_BINARY:?Set the absolute native binary path}"
+[[ ! -e $out ]] || { echo "Refusing to overwrite $out." >&2; exit 2; }
+mkdir -p "$out"
+out=$(realpath "$out")
+compose="$DW_PORT_SOURCE_ROOT/scripts/perf/server-port-multinode.compose.yml"
+# The SDK vendor directory is mounted over this ignored mount point.
+mkdir -p "$DW_PORT_SOURCE_ROOT/benchmarks/capacity/v1/bindings/php/vendor"
+log() { printf '%s %s\n' "$(date -u +%FT%T.%3NZ)" "$*" | tee -a "$out/run.log" >&2; }
+
+if [[ $mode == --smoke ]]; then
+  rate=0.5 offer=20 drain=120 windows=1 kill_every=8 down=3 pause_every=30
+else
+  # The drain outlasts the five-minute activity lease: an activity whose
+  # completion a killed node dropped is redelivered only when that lease expires.
+  rate=${DW_MN_RATE:-0.5} offer=${DW_MN_OFFER_SECONDS:-180} drain=${DW_MN_DRAIN_SECONDS:-420}
+  windows=${DW_MN_WINDOWS:-3} kill_every=${DW_MN_KILL_EVERY:-15} down=${DW_MN_DOWN_SECONDS:-4}
+  pause_every=${DW_MN_PAUSE_EVERY:-90}
+fi
+lease=${DW_MN_WORKFLOW_TASK_TIMEOUT:-60}
+pause=$((lease + 10))
+export DW_MN_WORKFLOW_TASK_TIMEOUT=$lease
+export DW_MN_HAPROXY_DIGEST=${DW_MN_HAPROXY_DIGEST:-094401c230b9bf01a6a4dc96e455795e261483f3bd2f42f19d0e6f259bd43837}
+export DW_MN_STATE_DIR="$out/state"
+mkdir -p "$DW_MN_STATE_DIR"
+chmod 0777 "$DW_MN_STATE_DIR"
+# Each run gets its own database secrets; the compose file requires them even
+# for profiles it does not start.
+secret() { od -An -N16 -tx1 /dev/urandom | tr -d ' \n'; }
+DW_MN_DB_PASSWORD=$(secret) DW_MN_DB_ROOT_PASSWORD=$(secret)
+export DW_MN_DB_PASSWORD DW_MN_DB_ROOT_PASSWORD
+case "$db" in
+  mysql) export DW_MN_DB_CONNECTION=mysql DW_MN_DB_HOST=mysql DW_MN_DB_DATABASE=durable_workflow \
+    DW_MN_DB_USERNAME=workflow; database=(mysql) ;;
+  mariadb) export DW_MN_DB_CONNECTION=mariadb DW_MN_DB_HOST=mariadb DW_MN_DB_DATABASE=durable_workflow \
+    DW_MN_DB_USERNAME=workflow; database=(mariadb) ;;
+  postgres) export DW_MN_DB_CONNECTION=pgsql DW_MN_DB_HOST=postgres DW_MN_DB_DATABASE=durable_workflow \
+    DW_MN_DB_USERNAME=workflow; database=(postgres) ;;
+  sqlite) export DW_MN_DB_CONNECTION=sqlite DW_MN_DB_DATABASE=/state/native.sqlite; database=() ;;
+  *) echo "Choose mysql, mariadb, postgres or sqlite." >&2; exit 2 ;;
+esac
+
+project="dw-mn-$db-$(date -u +%Y%m%dt%H%M%S)"
+dc() { docker compose -p "$project" -f "$compose" --profile "$db" "$@"; }
+container() { local service=$1; dc --profile clients ps -a -q "$service"; }
+nodes=(native-1 native-2 native-3)
+
+stop_file="$out/.stop"
+loops=()
+cleanup() {
+  status=$?
+  touch "$stop_file"
+  for pid in "${loops[@]}"; do kill "$pid" 2>/dev/null || true; wait "$pid" 2>/dev/null || true; done
+  docker unpause "$(container sdk-worker-1)" >/dev/null 2>&1 || true
+  for node in "${nodes[@]}"; do docker logs "$(container "$node")" > "$out/$node.log" 2>&1 || true; done
+  docker logs "$(container lb)" > "$out/lb.log" 2>&1 || true
+  for worker in sdk-worker-1 sdk-worker-2; do docker logs "$(container "$worker")" > "$out/$worker.log" 2>&1 || true; done
+  dc --profile clients ps -a --format json > "$out/containers-final.jsonl" 2>/dev/null || true
+  dc --profile clients down --volumes --remove-orphans >> "$out/run.log" 2>&1 || true
+  rm -rf "$DW_MN_STATE_DIR"
+  log "finished with status $status"
+  exit "$status"
+}
+trap cleanup EXIT
+
+jq -n --arg db "$db" --arg project "$project" --arg source "$(git -C "$DW_PORT_SOURCE_ROOT" rev-parse HEAD)" \
+  --arg dirty "$(git -C "$DW_PORT_SOURCE_ROOT" status --porcelain --untracked-files=no | wc -l)" \
+  --arg binary "$(sha256sum "$DW_PORT_NATIVE_BINARY" | cut -d ' ' -f1)" --arg smoke "$mode" \
+  --arg kernel "$(uname -r)" --arg cpus "$(nproc)" \
+  --arg cpu_model "$(awk -F': ' '/model name/ {print $2; exit}' /proc/cpuinfo)" \
+  --argjson schedule "$(jq -n --arg rate "$rate" --arg offer "$offer" --arg drain "$drain" --arg windows "$windows" \
+    --arg kill_every "$kill_every" --arg down "$down" --arg pause_every "$pause_every" --arg pause "$pause" --arg lease "$lease" \
+    '{rate:($rate|tonumber),offer_seconds:($offer|tonumber),drain_seconds:($drain|tonumber),windows:($windows|tonumber),
+      node_kill_every_seconds:($kill_every|tonumber),node_down_seconds:($down|tonumber),
+      worker_pause_every_seconds:($pause_every|tonumber),worker_pause_seconds:($pause|tonumber),
+      workflow_task_lease_seconds:($lease|tonumber)}')" \
+  '{database:$db,compose_project:$project,source_revision:$source,source_modified_files:($dirty|tonumber),native_binary_sha256:$binary,smoke:($smoke=="--smoke"),
+    schedule:$schedule,machine:{kernel:$kernel,logical_cpus:($cpus|tonumber),cpu_model:$cpu_model}}' > "$out/identity.json"
+
+log "starting $project"
+if (( ${#database[@]} )); then dc up -d --wait "${database[@]}" >> "$out/run.log" 2>&1; fi
+# All three nodes start at once against the empty database.
+dc up -d --wait "${nodes[@]}" >> "$out/run.log" 2>&1
+dc up -d lb >> "$out/run.log" 2>&1
+dc --profile clients up -d sdk-worker-1 sdk-worker-2 >> "$out/run.log" 2>&1
+
+# One node at a time is killed and restarted.
+kill_nodes() {
+  local i=0 node id
+  while [[ ! -e $stop_file ]]; do
+    sleep "$kill_every"
+    [[ -e $stop_file ]] && break
+    node=${nodes[$((i % 3))]}
+    id=$(container "$node")
+    printf '%s\tkill\t%s\n' "$(date -u +%s.%N)" "$node" >> "$out/chaos.tsv"
+    docker kill -s KILL "$id" >/dev/null 2>&1 || true
+    sleep "$down"
+    docker start "$id" >/dev/null 2>&1 || true
+    printf '%s\tstart\t%s\n' "$(date -u +%s.%N)" "$node" >> "$out/chaos.tsv"
+    i=$((i + 1))
+  done
+}
+# One SDK worker is frozen for longer than a workflow task lease, then
+# resumes with the tasks it held: its completions are stale by then.
+pause_worker() {
+  local id
+  while [[ ! -e $stop_file ]]; do
+    sleep "$pause_every"
+    [[ -e $stop_file ]] && break
+    id=$(container sdk-worker-1)
+    printf '%s\tpause\tsdk-worker-1\n' "$(date -u +%s.%N)" >> "$out/chaos.tsv"
+    docker pause "$id" >/dev/null 2>&1 || true
+    sleep "$pause"
+    docker unpause "$id" >/dev/null 2>&1 || true
+    printf '%s\tunpause\tsdk-worker-1\n' "$(date -u +%s.%N)" >> "$out/chaos.tsv"
+  done
+}
+kill_nodes & loops+=($!)
+pause_worker & loops+=($!)
+
+failed=0
+for window in $(seq 1 "$windows"); do
+  name="window-$window"
+  log "$name: $rate/s for ${offer}s"
+  if dc --profile clients run --rm --no-deps probe scripts/perf/multinode-workload.php "$rate" "$offer" "$drain" \
+    "mn-$db-w$window" > "$out/$name.json" 2> "$out/$name.stderr"; then
+    log "$name passed"
+  else
+    log "$name failed"
+    failed=1
+  fi
+done
+
+touch "$stop_file"
+for pid in "${loops[@]}"; do wait "$pid" 2>/dev/null || true; done
+loops=()
+for node in "${nodes[@]}"; do docker start "$(container "$node")" >/dev/null 2>&1 || true; done
+docker unpause "$(container sdk-worker-1)" >/dev/null 2>&1 || true
+
+# The balancer's request log shows what the chaos did: stale completions the
+# servers refused, and requests a killed node never answered.
+docker logs "$(container lb)" > "$out/lb.log" 2>&1 || true
+count() { local path=$1 status=$2; grep -E "$path" "$out/lb.log" | grep -cE "/[0-9-]+ $status " || true; }
+{
+  printf 'requests\t%s\n' "$(grep -cE '"[A-Z]+ /api/' "$out/lb.log" || true)"
+  printf 'workflow_task_completions_409\t%s\n' "$(count '/api/worker/workflow-tasks/[^ ]+/complete HTTP' 409)"
+  printf 'activity_task_completions_409\t%s\n' "$(count '/api/worker/activity-tasks/[^ ]+/complete HTTP' 409)"
+  printf 'responses_5xx\t%s\n' "$(count '"[A-Z]+ /api/' '5[0-9][0-9]')"
+} > "$out/lb-summary.tsv"
+
+audit_sql="SELECT 'runs', status, COUNT(*) FROM workflow_runs GROUP BY status;
+SELECT 'tasks', task_type, status, COUNT(*) FROM workflow_tasks GROUP BY task_type, status;
+SELECT 'attempts', status, COUNT(*) FROM activity_attempts GROUP BY status;
+SELECT 'duplicate_workflow_completions', COUNT(*) FROM (SELECT workflow_run_id FROM workflow_history_events WHERE event_type='WorkflowCompleted' GROUP BY workflow_run_id HAVING COUNT(*) > 1) d;
+SELECT 'duplicate_activity_completions', COUNT(*) FROM (SELECT activity_execution_id FROM activity_attempts WHERE status='completed' GROUP BY activity_execution_id HAVING COUNT(*) > 1) d;
+SELECT 'duplicate_history_sequences', COUNT(*) FROM (SELECT workflow_run_id, sequence FROM workflow_history_events GROUP BY workflow_run_id, sequence HAVING COUNT(*) > 1) d;"
+case "$db" in
+  mysql) dc exec -T mysql sh -c 'MYSQL_PWD=$MYSQL_PASSWORD exec mysql -u"$MYSQL_USER" "$MYSQL_DATABASE" --batch --skip-column-names -e "$1"' audit "$audit_sql" ;;
+  mariadb) dc exec -T mariadb sh -c 'MYSQL_PWD=$MARIADB_PASSWORD exec mariadb -u"$MARIADB_USER" "$MARIADB_DATABASE" --batch --skip-column-names -e "$1"' audit "$audit_sql" ;;
+  postgres) dc exec -T postgres psql -U workflow -d durable_workflow -At -F $'\t' -c "$audit_sql" ;;
+  sqlite) dc --profile clients run --rm --no-deps -v "$DW_MN_STATE_DIR:/state" -e AUDIT_SQL="$audit_sql" probe -r '
+    $pdo = new PDO("sqlite:/state/native.sqlite");
+    foreach (array_filter(array_map("trim", explode(";", getenv("AUDIT_SQL")))) as $sql) {
+        foreach ($pdo->query($sql, PDO::FETCH_NUM) as $row) { echo implode("\t", $row), "\n"; }
+    }' ;;
+  *) echo "Unknown database $db." >&2; exit 2 ;;
+esac > "$out/database-audit.tsv" 2>> "$out/run.log"
+for kind in workflow activity; do
+  awk -F'\t' -v k="duplicate_${kind}_completions" '$1==k && $2!=0 {bad=1} END {exit bad}' "$out/database-audit.tsv" || failed=1
+done
+awk -F'\t' '$1=="duplicate_history_sequences" && $2!=0 {bad=1} END {exit bad}' "$out/database-audit.tsv" || failed=1
+awk -F'\t' '$1=="runs" && $2!="completed" {bad=1} END {exit bad}' "$out/database-audit.tsv" || failed=1
+for node in "${nodes[@]}"; do docker logs "$(container "$node")" 2>&1 | grep -c "panicked" > "$out/$node-panics.txt" || true; done
+for id in $(dc --profile clients ps -a -q); do
+  docker inspect --format '{{index .Config.Labels "com.docker.compose.service"}} restarts={{.RestartCount}} oom={{.State.OOMKilled}} exit={{.State.ExitCode}}' "$id"
+done > "$out/container-states.txt"
+log "audit: $(tr '\n' ' ' < "$out/database-audit.tsv")"
+exit "$failed"
diff --git a/scripts/perf/server-port-multinode.compose.yml b/scripts/perf/server-port-multinode.compose.yml
new file mode 100644
index 000000000..f2158fda3
--- /dev/null
+++ b/scripts/perf/server-port-multinode.compose.yml
@@ -0,0 +1,147 @@
+# Multi-node native qualification: three native nodes share one database
+# behind a load balancer, while run-server-port-multinode.sh kills and
+# restarts them. Choose exactly one database profile: mysql, mariadb, postgres or
+# sqlite.
+x-native: &native
+  stop_signal: SIGTERM
+  image: &php_image durableworkflow/server@sha256:944c384c9875fd82637dd2bdea74dcb881cf983a57599ba0e492bec706296549
+  platform: linux/amd64
+  user: "1000:1000"
+  entrypoint: [/native/server]
+  environment:
+    DW_RUST_EXPERIMENTAL: "1"
+    DW_BIND_ADDRESS: 0.0.0.0:8080
+    DW_AUTH_DRIVER: token
+    DW_AUTH_TOKEN: multinode-test-token
+    DW_WORKFLOW_TASK_TIMEOUT: "${DW_MN_WORKFLOW_TASK_TIMEOUT:-60}"
+    DB_CONNECTION: "${DW_MN_DB_CONNECTION:?Set the database connection}"
+    DB_HOST: "${DW_MN_DB_HOST:-}"
+    DB_DATABASE: "${DW_MN_DB_DATABASE:?Set the database}"
+    DB_USERNAME: "${DW_MN_DB_USERNAME:-}"
+    DB_PASSWORD: "${DW_MN_DB_PASSWORD:-}"
+  volumes:
+    - "${DW_PORT_NATIVE_BINARY:?Set the absolute native binary path}:/native/server:ro"
+    - "${DW_MN_STATE_DIR:?Set the shared state directory}:/state"
+  cpus: 1
+  mem_limit: 512m
+  memswap_limit: 512m
+  restart: "no"
+  healthcheck:
+    test: [CMD, curl, --fail, --silent, http://127.0.0.1:8080/api/ready]
+    interval: 2s
+    timeout: 3s
+    retries: 30
+
+x-client: &client
+  image: *php_image
+  platform: linux/amd64
+  user: "1000:1000"
+  entrypoint: [php]
+  working_dir: /source
+  environment: &client_environment
+    DURABLE_WORKFLOW_RUNTIME_URL: http://lb:8080
+    DURABLE_WORKFLOW_NAMESPACE: default
+    DURABLE_WORKFLOW_TASK_QUEUE: multinode
+    DURABLE_WORKFLOW_TOKEN: multinode-test-token
+    DURABLE_WORKFLOW_CAPACITY_CELL: one-activity
+    DURABLE_WORKFLOW_WORKER_CONCURRENCY: "1"
+  volumes:
+    - "${DW_PORT_SOURCE_ROOT:?Set the absolute source directory}:/source:ro"
+    - "${DW_PORT_SDK_ROOT:?Set the normally installed SDK directory}/vendor:/source/benchmarks/capacity/v1/bindings/php/vendor:ro"
+  cpus: 0.5
+  mem_limit: 512m
+  memswap_limit: 512m
+  restart: "no"
+
+services:
+  mysql:
+    profiles: [mysql]
+    image: mysql@sha256:679e7e924f38a3cbb62a3d7df32924b83f7321a602d3f9f967c01b3df18495d6
+    platform: linux/amd64
+    environment:
+      MYSQL_DATABASE: durable_workflow
+      MYSQL_USER: workflow
+      # The driver generates both secrets for each run.
+      MYSQL_PASSWORD: ${DW_MN_DB_PASSWORD:?Run through run-server-port-multinode.sh}
+      MYSQL_ROOT_PASSWORD: ${DW_MN_DB_ROOT_PASSWORD:?Run through run-server-port-multinode.sh}
+    command: ["--innodb-flush-log-at-trx-commit=1", "--sync-binlog=1"]
+    cpus: 1
+    mem_limit: 1024m
+    memswap_limit: 1024m
+    restart: "no"
+    healthcheck:
+      test: [CMD-SHELL, "MYSQL_PWD=$$MYSQL_PASSWORD mysqladmin ping --silent -h 127.0.0.1 -u workflow"]
+      interval: 2s
+      timeout: 3s
+      retries: 30
+
+  mariadb:
+    profiles: [mariadb]
+    # The digest the shared fixtures' MariaDB 10.11 jobs use.
+    image: mirror.gcr.io/library/mariadb@sha256:7db29378d4fdab73f8123bbc2b48905c90d1a4b00cf848b028f1e81e623257f2
+    environment:
+      MARIADB_DATABASE: durable_workflow
+      MARIADB_USER: workflow
+      # The driver generates both secrets for each run.
+      MARIADB_PASSWORD: ${DW_MN_DB_PASSWORD:?Run through run-server-port-multinode.sh}
+      MARIADB_ROOT_PASSWORD: ${DW_MN_DB_ROOT_PASSWORD:?Run through run-server-port-multinode.sh}
+    command: ["--innodb-flush-log-at-trx-commit=1", "--sync-binlog=1"]
+    cpus: 1
+    mem_limit: 1024m
+    memswap_limit: 1024m
+    restart: "no"
+    healthcheck:
+      test: [CMD, healthcheck.sh, --connect, --innodb_initialized]
+      interval: 2s
+      timeout: 3s
+      retries: 30
+
+  postgres:
+    profiles: [postgres]
+    image: mirror.gcr.io/library/postgres@sha256:3645570cccdfa447589da9f57dd740faa29b30938e861289a5574b6ca6b03826
+    environment:
+      POSTGRES_DB: durable_workflow
+      POSTGRES_USER: workflow
+      # The driver generates the secret for each run.
+      POSTGRES_PASSWORD: ${DW_MN_DB_PASSWORD:?Run through run-server-port-multinode.sh}
+    cpus: 1
+    mem_limit: 1024m
+    memswap_limit: 1024m
+    restart: "no"
+    healthcheck:
+      test: [CMD-SHELL, "pg_isready -U workflow -d durable_workflow"]
+      interval: 2s
+      timeout: 3s
+      retries: 30
+
+  native-1: *native
+  native-2: *native
+  native-3: *native
+
+  lb:
+    image: mirror.gcr.io/library/haproxy@sha256:${DW_MN_HAPROXY_DIGEST:?Set the pinned HAProxy digest}
+    user: "1000:1000"
+    volumes:
+      - "${DW_PORT_SOURCE_ROOT}/scripts/perf/multinode-haproxy.cfg:/usr/local/etc/haproxy/haproxy.cfg:ro"
+    cpus: 0.5
+    mem_limit: 128m
+    memswap_limit: 128m
+    restart: "no"
+
+  sdk-worker-1:
+    <<: *client
+    profiles: [clients]
+    # A supervisor restarts a worker that exits; the run records each restart.
+    restart: on-failure
+    stop_signal: SIGTERM
+    command: [benchmarks/capacity/v1/bindings/php/capacity_adapter.php, worker]
+  sdk-worker-2:
+    <<: *client
+    profiles: [clients]
+    # A supervisor restarts a worker that exits; the run records each restart.
+    restart: on-failure
+    stop_signal: SIGTERM
+    command: [benchmarks/capacity/v1/bindings/php/capacity_adapter.php, worker]
+  probe:
+    <<: *client
+    profiles: [clients]