diff --git a/dev/mail-testbed/.env.example b/dev/mail-testbed/.env.example
index fa566e4..5ff5b8d 100644
--- a/dev/mail-testbed/.env.example
+++ b/dev/mail-testbed/.env.example
@@ -9,3 +9,5 @@ GOVOPLAN_MAIL_TEST_IMAP_PORT=3143
 GOVOPLAN_MAIL_TEST_SENT_FOLDER=Sent
 GOVOPLAN_MAIL_TEST_ZIP_PASSWORD=zip-test-password
 GOVOPLAN_MAIL_TEST_READY_TIMEOUT_SECONDS=45
+GOVOPLAN_CAMPAIGN_TEST_REDIS_PORT=36379
+GOVOPLAN_CAMPAIGN_TEST_REDIS_VISIBILITY_TIMEOUT_SECONDS=3
diff --git a/dev/mail-testbed/docker-compose.yml b/dev/mail-testbed/docker-compose.yml
index 9aedd4e..0ad279e 100644
--- a/dev/mail-testbed/docker-compose.yml
+++ b/dev/mail-testbed/docker-compose.yml
@@ -15,3 +15,19 @@ services:
       - "${GOVOPLAN_MAIL_TEST_SMTP_PORT:-3025}:3025"
       - "${GOVOPLAN_MAIL_TEST_IMAP_PORT:-3143}:3143"
       - "127.0.0.1:38080:8080"
+
+  redis:
+    image: redis:7-alpine
+    command: ["redis-server", "--appendonly", "yes"]
+    ports:
+      - "127.0.0.1:${GOVOPLAN_CAMPAIGN_TEST_REDIS_PORT:-36379}:6379"
+    healthcheck:
+      test: ["CMD", "redis-cli", "ping"]
+      interval: 1s
+      timeout: 1s
+      retries: 30
+    volumes:
+      - campaign-redis-data:/data
+
+volumes:
+  campaign-redis-data:
diff --git a/dev/mail-testbed/run_celery_redelivery_acceptance.py b/dev/mail-testbed/run_celery_redelivery_acceptance.py
new file mode 100644
index 0000000..bc44b03
--- /dev/null
+++ b/dev/mail-testbed/run_celery_redelivery_acceptance.py
@@ -0,0 +1,852 @@
+#!/usr/bin/env python3
+"""Prove Redis/Celery redelivery does not repeat an ambiguous SMTP effect.
+
+The default run starts an isolated Redis Compose service, two successive real
+Celery worker processes, and a controlled loopback SMTP endpoint. It kills the
+first worker after complete DATA but before a final SMTP response. The same
+unacknowledged broker task must be delivered to the replacement worker, which
+must freeze the unfinished durable attempt as ``outcome_unknown`` without a
+second SMTP connection or DATA transaction.
+"""
+
+from __future__ import annotations
+
+import argparse
+from collections import Counter
+from contextlib import contextmanager
+from dataclasses import dataclass, replace
+from datetime import datetime, timezone
+import hashlib
+import json
+import os
+from pathlib import Path
+import re
+import shutil
+import socket
+import subprocess
+import sys
+import tempfile
+import time
+from typing import Any, Callable, Iterator, Mapping
+from uuid import uuid4
+
+from redis import Redis
+from redis.exceptions import RedisError
+
+
+SCRIPT_ROOT = Path(__file__).resolve().parent
+REPOSITORY_ROOT = SCRIPT_ROOT.parents[1]
+if str(SCRIPT_ROOT) not in sys.path:
+    sys.path.insert(0, str(SCRIPT_ROOT))
+
+from run_campaign_acceptance import (  # noqa: E402
+    AcceptanceError,
+    DEFAULT_FIXTURE,
+    EXPECTED_AUDIT_ACTIONS,
+    TestbedSettings,
+    _assert_evidence_safe,
+    _core_package_version,
+    _durable_state_evidence,
+    _expect,
+    _report_evidence,
+    create_mail_profile,
+    prepare_campaign_scenario,
+    required_composition_versions,
+    smtp_fault_endpoint,
+)
+
+
+EVIDENCE_SCHEMA = "govoplan.campaign.celery-redelivery-acceptance.v1"
+MAX_EVIDENCE_BYTES = 128 * 1024
+DEFAULT_COMPOSE_FILE = SCRIPT_ROOT / "docker-compose.yml"
+TASK_RECEIVED_PATTERN = re.compile(
+    r"Task govoplan[.]campaigns[.]send_email\[([0-9a-f-]{36})\] received",
+    re.IGNORECASE,
+)
+TASK_SUCCEEDED_PATTERN = re.compile(
+    r"Task govoplan[.]campaigns[.]send_email\[([0-9a-f-]{36})\] succeeded",
+    re.IGNORECASE,
+)
+WORKER_BOOTSTRAP = r"""
+import os
+import sys
+
+from govoplan_core.celery_app import celery
+
+visibility_timeout = int(os.environ["GOVOPLAN_CAMPAIGN_TEST_REDIS_VISIBILITY_TIMEOUT_SECONDS"])
+celery.conf.broker_transport_options = {
+    **dict(celery.conf.broker_transport_options or {}),
+    "polling_interval": 0.25,
+    "visibility_timeout": visibility_timeout,
+}
+celery.worker_main(
+    [
+        "worker",
+        "--loglevel=INFO",
+        "--pool=solo",
+        "--concurrency=1",
+        "--queues=send_email",
+        f"--hostname={sys.argv[1]}@%h",
+        "--without-gossip",
+        "--without-mingle",
+        "--without-heartbeat",
+    ]
+)
+"""
+
+
+@dataclass(slots=True)
+class WorkerProcess:
+    process: subprocess.Popen[bytes]
+    log_path: Path
+    log_handle: Any
+
+    def text(self) -> str:
+        self.log_handle.flush()
+        try:
+            return self.log_path.read_text(encoding="utf-8", errors="replace")
+        except OSError as exc:
+            raise AcceptanceError("Celery worker evidence log could not be read") from exc
+
+    def received_task_ids(self) -> tuple[str, ...]:
+        return tuple(TASK_RECEIVED_PATTERN.findall(self.text()))
+
+    def succeeded_task_ids(self) -> tuple[str, ...]:
+        return tuple(TASK_SUCCEEDED_PATTERN.findall(self.text()))
+
+
+@dataclass(frozen=True, slots=True)
+class RedisBrokerState:
+    queue_depth: int
+    unacked_hash_count: int
+    unacked_index_count: int
+
+    def as_dict(self) -> dict[str, int]:
+        return {
+            "queue_depth": self.queue_depth,
+            "unacked_hash_count": self.unacked_hash_count,
+            "unacked_index_count": self.unacked_index_count,
+        }
+
+
+def _positive_int(value: str, *, label: str) -> int:
+    try:
+        parsed = int(value)
+    except ValueError as exc:
+        raise argparse.ArgumentTypeError(f"{label} must be a positive integer") from exc
+    if parsed <= 0:
+        raise argparse.ArgumentTypeError(f"{label} must be a positive integer")
+    return parsed
+
+
+def _unused_loopback_port() -> int:
+    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as probe:
+        probe.bind(("127.0.0.1", 0))
+        return int(probe.getsockname()[1])
+
+
+def _compose_command(
+    *, compose_file: Path, project_name: str, operation: str
+) -> list[str]:
+    prefix = [
+        "docker",
+        "compose",
+        "--file",
+        str(compose_file),
+        "--project-name",
+        project_name,
+    ]
+    if operation == "up":
+        return [*prefix, "up", "--detach", "redis"]
+    if operation == "down":
+        return [*prefix, "down", "--volumes", "--remove-orphans"]
+    raise AcceptanceError("Unsupported Redis Compose operation")
+
+
+def _run_compose(
+    command: list[str],
+    *,
+    environment: Mapping[str, str],
+    timeout_seconds: int,
+) -> None:
+    try:
+        completed = subprocess.run(
+            command,
+            env=dict(environment),
+            stdin=subprocess.DEVNULL,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE,
+            timeout=timeout_seconds,
+            check=False,
+        )
+    except (OSError, subprocess.TimeoutExpired) as exc:
+        raise AcceptanceError("Redis Compose lifecycle command failed") from exc
+    if completed.returncode != 0:
+        raise AcceptanceError("Redis Compose lifecycle command failed")
+
+
+def _wait_for_redis(redis_url: str, *, timeout_seconds: int) -> None:
+    deadline = time.monotonic() + timeout_seconds
+    client = Redis.from_url(
+        redis_url,
+        socket_connect_timeout=1,
+        socket_timeout=1,
+        decode_responses=False,
+    )
+    try:
+        while time.monotonic() < deadline:
+            try:
+                if client.ping() is True:
+                    return
+            except RedisError:
+                pass
+            time.sleep(0.25)
+    finally:
+        client.close()
+    raise AcceptanceError("Isolated Redis broker did not become ready")
+
+
+@contextmanager
+def isolated_redis_broker(
+    *,
+    compose_file: Path,
+    timeout_seconds: int,
+    requested_port: int | None = None,
+) -> Iterator[str]:
+    if shutil.which("docker") is None:
+        raise AcceptanceError("Docker CLI is required to start the isolated Redis broker")
+    if not compose_file.is_file():
+        raise AcceptanceError("Redis Compose definition is unavailable")
+    port = requested_port or _unused_loopback_port()
+    if port <= 0 or port > 65_535:
+        raise AcceptanceError("Redis test port is invalid")
+    project_name = f"govoplan-campaign-redelivery-{uuid4().hex[:12]}"
+    environment = {
+        **os.environ,
+        "GOVOPLAN_CAMPAIGN_TEST_REDIS_PORT": str(port),
+    }
+    lifecycle_attempted = False
+    try:
+        lifecycle_attempted = True
+        _run_compose(
+            _compose_command(
+                compose_file=compose_file,
+                project_name=project_name,
+                operation="up",
+            ),
+            environment=environment,
+            timeout_seconds=timeout_seconds,
+        )
+        redis_url = f"redis://127.0.0.1:{port}/0"
+        _wait_for_redis(redis_url, timeout_seconds=timeout_seconds)
+        yield redis_url
+    finally:
+        if lifecycle_attempted:
+            _run_compose(
+                _compose_command(
+                    compose_file=compose_file,
+                    project_name=project_name,
+                    operation="down",
+                ),
+                environment=environment,
+                timeout_seconds=timeout_seconds,
+            )
+
+
+def _start_worker(runtime_root: Path, *, label: str) -> WorkerProcess:
+    log_path = runtime_root / f"{label}.log"
+    log_handle = log_path.open("wb")
+    environment = {**os.environ, "PYTHONUNBUFFERED": "1"}
+    try:
+        process = subprocess.Popen(
+            [sys.executable, "-c", WORKER_BOOTSTRAP, label],
+            env=environment,
+            stdin=subprocess.DEVNULL,
+            stdout=log_handle,
+            stderr=subprocess.STDOUT,
+            close_fds=True,
+        )
+    except Exception:
+        log_handle.close()
+        raise
+    return WorkerProcess(process=process, log_path=log_path, log_handle=log_handle)
+
+
+def _wait_for_worker_ready(worker: WorkerProcess, *, timeout_seconds: int) -> None:
+    deadline = time.monotonic() + timeout_seconds
+    while time.monotonic() < deadline:
+        if worker.process.poll() is not None:
+            raise AcceptanceError("Celery worker exited before becoming ready")
+        if " ready." in worker.text():
+            return
+        time.sleep(0.2)
+    raise AcceptanceError("Celery worker did not become ready")
+
+
+def _wait_for_received_task(
+    worker: WorkerProcess,
+    *,
+    timeout_seconds: int,
+    expected_task_id: str | None = None,
+) -> str:
+    deadline = time.monotonic() + timeout_seconds
+    while time.monotonic() < deadline:
+        received = worker.received_task_ids()
+        if received:
+            if len(set(received)) != 1:
+                raise AcceptanceError("Celery worker received more than one task identity")
+            task_id = received[0]
+            if expected_task_id is not None and task_id != expected_task_id:
+                raise AcceptanceError("Replacement worker received a different broker task")
+            return task_id
+        if worker.process.poll() is not None:
+            raise AcceptanceError("Celery worker exited before receiving the task")
+        time.sleep(0.2)
+    raise AcceptanceError("Celery worker did not receive the broker task")
+
+
+def _wait_for_task_success(
+    worker: WorkerProcess,
+    *,
+    task_id: str,
+    timeout_seconds: int,
+) -> None:
+    deadline = time.monotonic() + timeout_seconds
+    while time.monotonic() < deadline:
+        succeeded = worker.succeeded_task_ids()
+        if task_id in succeeded:
+            return
+        if worker.process.poll() is not None:
+            raise AcceptanceError("Replacement Celery worker exited before task success")
+        time.sleep(0.2)
+    raise AcceptanceError("Redelivered Celery task did not complete")
+
+
+def _kill_worker(worker: WorkerProcess, *, timeout_seconds: int) -> int:
+    if worker.process.poll() is not None:
+        raise AcceptanceError("Celery worker exited before controlled termination")
+    worker.process.kill()
+    try:
+        return_code = worker.process.wait(timeout=timeout_seconds)
+    except subprocess.TimeoutExpired as exc:
+        raise AcceptanceError("Celery worker could not be killed") from exc
+    if return_code == 0:
+        raise AcceptanceError("Celery worker termination was not forced")
+    return return_code
+
+
+def _stop_worker(worker: WorkerProcess, *, timeout_seconds: int) -> None:
+    if worker.process.poll() is None:
+        worker.process.terminate()
+        try:
+            worker.process.wait(timeout=timeout_seconds)
+        except subprocess.TimeoutExpired:
+            worker.process.kill()
+            worker.process.wait(timeout=timeout_seconds)
+    worker.log_handle.close()
+
+
+def _broker_state(redis_url: str) -> RedisBrokerState:
+    client = Redis.from_url(
+        redis_url,
+        socket_connect_timeout=2,
+        socket_timeout=2,
+        decode_responses=False,
+    )
+    try:
+        return RedisBrokerState(
+            queue_depth=int(client.llen("send_email")),
+            unacked_hash_count=int(client.hlen("unacked")),
+            unacked_index_count=int(client.zcard("unacked_index")),
+        )
+    except RedisError as exc:
+        raise AcceptanceError("Redis broker state could not be inspected") from exc
+    finally:
+        client.close()
+
+
+def _wait_for_broker_drained(
+    redis_url: str,
+    *,
+    timeout_seconds: int,
+) -> RedisBrokerState:
+    deadline = time.monotonic() + timeout_seconds
+    last = RedisBrokerState(0, 0, 0)
+    while time.monotonic() < deadline:
+        last = _broker_state(redis_url)
+        if last == RedisBrokerState(0, 0, 0):
+            return last
+        time.sleep(0.2)
+    raise AcceptanceError("Redis broker retained delivery state after recovery")
+
+
+def _queue_evidence(payload: Mapping[str, Any]) -> dict[str, Any]:
+    expected = {
+        "queued_count": 1,
+        "skipped_count": 0,
+        "blocked_count": 0,
+        "enqueued_count": 1,
+        "delivery_mode": "worker_queue",
+        "worker_queue_available": True,
+        "dry_run": False,
+    }
+    evidence = {key: payload.get(key) for key in expected}
+    if evidence != expected:
+        raise AcceptanceError("Campaign was not durably queued to one Celery task")
+    return evidence
+
+
+def execute_redelivery_scenario(
+    client: Any,
+    headers: Mapping[str, str],
+    *,
+    fixture_path: Path,
+    settings: TestbedSettings,
+    endpoint: Any,
+    redis_url: str,
+    runtime_root: Path,
+    snapshot_probe: Callable[[str], tuple[Mapping[str, Any], Mapping[str, Any]]],
+    audit_probe: Callable[[str, str], Mapping[str, int]],
+    delivery_probe: Callable[[str, str], Mapping[str, Any]],
+) -> dict[str, Any]:
+    profile_id = create_mail_profile(
+        client,
+        headers,
+        settings,
+        name="Campaign Redis Celery redelivery drill",
+        smtp_host=endpoint.host,
+        smtp_port=endpoint.port,
+    )
+    prepared = prepare_campaign_scenario(
+        client,
+        headers,
+        fixture_path=fixture_path,
+        profile_id=profile_id,
+        settings=settings,
+        scenario="celery_broker_redelivery",
+        snapshot_probe=snapshot_probe,
+    )
+
+    first_worker = _start_worker(runtime_root, label="first-worker")
+    replacement_worker: WorkerProcess | None = None
+    try:
+        _wait_for_worker_ready(
+            first_worker,
+            timeout_seconds=settings.provider_timeout_seconds,
+        )
+        queued = _expect(
+            client.post(
+                f"/api/v1/campaigns/{prepared.campaign_id}/queue",
+                headers=dict(headers),
+                json={
+                    "version_id": prepared.version_id,
+                    "include_warnings": True,
+                    "enqueue_celery": True,
+                    "dry_run": False,
+                },
+            ),
+            200,
+            "Celery-redelivery Campaign queue",
+        )
+        queue_evidence = _queue_evidence(queued)
+        first_task_id = _wait_for_received_task(
+            first_worker,
+            timeout_seconds=settings.provider_timeout_seconds,
+        )
+        if not endpoint.wait_for_data(settings.provider_timeout_seconds):
+            raise AcceptanceError("Celery worker did not reach complete SMTP DATA")
+        first_exit_code = _kill_worker(
+            first_worker,
+            timeout_seconds=settings.provider_timeout_seconds,
+        )
+        endpoint.release_held_connection()
+
+        interrupted_state = _durable_state_evidence(
+            delivery_probe(prepared.campaign_id, prepared.version_id)
+        )
+        expected_interrupted = {
+            "job_count": 1,
+            "send_status_counts": {"sending": 1},
+            "attempt_status_counts": {"smtp_in_progress": 1},
+            "unfinished_attempt_count": 1,
+        }
+        if interrupted_state != expected_interrupted:
+            raise AcceptanceError("Killed worker state was not durably SMTP-in-progress")
+
+        replacement_worker = _start_worker(runtime_root, label="replacement-worker")
+        _wait_for_worker_ready(
+            replacement_worker,
+            timeout_seconds=settings.provider_timeout_seconds,
+        )
+        redelivered_task_id = _wait_for_received_task(
+            replacement_worker,
+            timeout_seconds=settings.provider_timeout_seconds,
+            expected_task_id=first_task_id,
+        )
+        _wait_for_task_success(
+            replacement_worker,
+            task_id=redelivered_task_id,
+            timeout_seconds=settings.provider_timeout_seconds,
+        )
+        recovered_state = _durable_state_evidence(
+            delivery_probe(prepared.campaign_id, prepared.version_id)
+        )
+        expected_recovered = {
+            "job_count": 1,
+            "send_status_counts": {"outcome_unknown": 1},
+            "attempt_status_counts": {"outcome_unknown": 1},
+            "unfinished_attempt_count": 0,
+        }
+        if recovered_state != expected_recovered:
+            raise AcceptanceError("Redelivered task did not freeze the unfinished attempt")
+
+        protocol = endpoint.evidence()
+        expected_protocol = {
+            "connection_count": 1,
+            "accepted_rcpt_commands": 1,
+            "refused_rcpt_commands": 0,
+            "data_transactions": 1,
+        }
+        if protocol != expected_protocol:
+            raise AcceptanceError("Broker redelivery caused an unexpected SMTP transaction")
+        broker_after = _wait_for_broker_drained(
+            redis_url,
+            timeout_seconds=settings.provider_timeout_seconds,
+        )
+        first_received = first_worker.received_task_ids()
+        replacement_received = replacement_worker.received_task_ids()
+        if first_received != (first_task_id,) or replacement_received != (
+            redelivered_task_id,
+        ):
+            raise AcceptanceError(
+                "Celery workers did not each receive the broker task exactly once"
+            )
+        report = _report_evidence(
+            _expect(
+                client.get(
+                    f"/api/v1/campaigns/{prepared.campaign_id}/report",
+                    headers=dict(headers),
+                    params={"version_id": prepared.version_id},
+                ),
+                200,
+                "Celery-redelivery Campaign report",
+            )
+        )
+        if report["send_status_counts"] != {"outcome_unknown": 1}:
+            raise AcceptanceError("Campaign report did not retain outcome_unknown")
+        audit_actions = dict(
+            sorted(audit_probe(prepared.campaign_id, prepared.version_id).items())
+        )
+        if not {
+            "campaign.created",
+            "campaign.validated",
+            "campaign.messages_built",
+            "campaign.queued",
+        }.issubset(audit_actions):
+            raise AcceptanceError("Celery-redelivery Campaign audit evidence is incomplete")
+
+        return {
+            **prepared.public_evidence(),
+            "queue": queue_evidence,
+            "interrupted_durable_state": interrupted_state,
+            "recovered_durable_state": recovered_state,
+            "protocol": protocol,
+            "report": report,
+            "audit_actions": audit_actions,
+            "broker": {
+                "transport": "redis",
+                "same_task_identity_redelivered": first_task_id
+                == redelivered_task_id,
+                "first_worker_received_count": len(first_received),
+                "replacement_worker_received_count": len(replacement_received),
+                **broker_after.as_dict(),
+            },
+            "supervision": {
+                "first_worker_killed_after_complete_data": True,
+                "first_worker_forced_exit": first_exit_code != 0,
+                "replacement_worker_started": True,
+                "replacement_worker_completed_redelivery": True,
+            },
+        }
+    finally:
+        endpoint.release_held_connection()
+        _stop_worker(first_worker, timeout_seconds=5)
+        if replacement_worker is not None:
+            _stop_worker(replacement_worker, timeout_seconds=5)
+
+
+def _runtime_module_versions(registry: Any) -> dict[str, str]:
+    versions = {"core": _core_package_version()}
+    versions.update(
+        {
+            manifest.id: manifest.version
+            for manifest in registry.manifests()
+            if manifest.id in {"access", "audit", "campaigns", "mail"}
+        }
+    )
+    return versions
+
+
+def _bootstrap_and_run(
+    *,
+    settings: TestbedSettings,
+    fixture_path: Path,
+    redis_url: str,
+    visibility_timeout_seconds: int,
+) -> dict[str, Any]:
+    runtime_root = Path(
+        tempfile.mkdtemp(prefix="govoplan-campaign-celery-redelivery-", dir="/tmp")
+    )
+    database = None
+    try:
+        os.environ.update(
+            {
+                "APP_ENV": "test",
+                "DATABASE_URL": f"sqlite:///{runtime_root / 'acceptance.db'}",
+                "FILE_STORAGE_BACKEND": "local",
+                "FILE_STORAGE_LOCAL_ROOT": str(runtime_root / "files"),
+                "MOCK_MAILBOX_DIR": str(runtime_root / "mock-mailbox"),
+                "DEV_BOOTSTRAP_ENABLED": "false",
+                "CELERY_ENABLED": "true",
+                "REDIS_URL": redis_url,
+                "GOVOPLAN_CAMPAIGN_TEST_REDIS_VISIBILITY_TIMEOUT_SECONDS": str(
+                    visibility_timeout_seconds
+                ),
+                "GOVOPLAN_CONNECTOR_ALLOW_PRIVATE_NETWORKS": "true",
+            }
+        )
+        from fastapi.testclient import TestClient
+
+        from govoplan_core.db.base import Base
+        from govoplan_core.db.bootstrap import bootstrap_dev_data
+        from govoplan_core.db.session import configure_database, set_database
+        from govoplan_core.settings import Settings, settings as core_settings
+        from govoplan_core.tenancy.scope import create_scope_tables
+
+        isolated_settings = Settings()
+        for field_name in Settings.model_fields:
+            setattr(core_settings, field_name, getattr(isolated_settings, field_name))
+        database = configure_database(os.environ["DATABASE_URL"])
+        set_database(database)
+
+        from govoplan_core.server.app import app
+
+        create_scope_tables(database.engine)
+        Base.metadata.create_all(bind=database.engine)
+        with database.SessionLocal() as session:
+            bootstrap_dev_data(
+                session,
+                api_key_secret="celery-redelivery-unused-api-key",
+                user_password="celery-redelivery-admin",
+            )
+
+        def snapshot_probe(
+            version_id: str,
+        ) -> tuple[Mapping[str, Any], Mapping[str, Any]]:
+            from govoplan_campaign.backend.db.models import CampaignVersion
+
+            with database.SessionLocal() as session:
+                version = session.get(CampaignVersion, version_id)
+                if version is None:
+                    raise AcceptanceError("Campaign execution snapshot is unavailable")
+                raw = version.raw_json if isinstance(version.raw_json, dict) else {}
+                snapshot = (
+                    version.execution_snapshot
+                    if isinstance(version.execution_snapshot, dict)
+                    else {}
+                )
+                return raw, snapshot
+
+        def audit_probe(campaign_id: str, version_id: str) -> Mapping[str, int]:
+            from govoplan_audit.backend.db.models import AuditLog
+
+            with database.SessionLocal() as session:
+                actions = [
+                    row[0]
+                    for row in session.query(AuditLog.action)
+                    .filter(AuditLog.object_id.in_([campaign_id, version_id]))
+                    .all()
+                    if row[0] in EXPECTED_AUDIT_ACTIONS
+                ]
+            return dict(Counter(actions))
+
+        def delivery_probe(campaign_id: str, version_id: str) -> Mapping[str, Any]:
+            from govoplan_campaign.backend.db.models import CampaignJob, SendAttempt
+
+            with database.SessionLocal() as session:
+                jobs = (
+                    session.query(CampaignJob)
+                    .filter(
+                        CampaignJob.campaign_id == campaign_id,
+                        CampaignJob.campaign_version_id == version_id,
+                    )
+                    .all()
+                )
+                job_ids = [job.id for job in jobs]
+                attempts = (
+                    session.query(SendAttempt)
+                    .filter(SendAttempt.job_id.in_(job_ids))
+                    .all()
+                    if job_ids
+                    else []
+                )
+                return {
+                    "job_count": len(jobs),
+                    "send_status_counts": dict(
+                        Counter(job.send_status for job in jobs)
+                    ),
+                    "attempt_status_counts": dict(
+                        Counter(attempt.status for attempt in attempts)
+                    ),
+                    "unfinished_attempt_count": sum(
+                        1 for attempt in attempts if attempt.finished_at is None
+                    ),
+                }
+
+        with TestClient(app) as client:
+            login = _expect(
+                client.post(
+                    "/api/v1/auth/login",
+                    json={
+                        "email": "admin@example.local",
+                        "password": "celery-redelivery-admin",
+                    },
+                ),
+                200,
+                "Acceptance login",
+            )
+            access_token = str(login.get("access_token") or "")
+            if not access_token:
+                raise AcceptanceError("Acceptance login returned no access token")
+            from govoplan_core.core.runtime import get_registry
+
+            registry = get_registry()
+            if registry is None:
+                raise AcceptanceError("The GovOPlaN module registry is unavailable")
+            composition_versions = required_composition_versions(
+                fixture_path,
+                _runtime_module_versions(registry),
+            )
+            with smtp_fault_endpoint("post_data_hold") as endpoint:
+                scenario = execute_redelivery_scenario(
+                    client,
+                    {"Authorization": f"Bearer {access_token}"},
+                    fixture_path=fixture_path,
+                    settings=settings,
+                    endpoint=endpoint,
+                    redis_url=redis_url,
+                    runtime_root=runtime_root,
+                    snapshot_probe=snapshot_probe,
+                    audit_probe=audit_probe,
+                    delivery_probe=delivery_probe,
+                )
+
+        evidence = {
+            "schema_version": EVIDENCE_SCHEMA,
+            "generated_at": datetime.now(timezone.utc).isoformat(),
+            "fixture_sha256": hashlib.sha256(fixture_path.read_bytes()).hexdigest(),
+            "declared_module_versions": composition_versions,
+            "target": {
+                "kind": "local_redis_celery_controlled_smtp",
+                "isolated_temporary_database": True,
+                "redis_started_by_runner": True,
+                "worker_pool": "solo",
+                "worker_prefetch_multiplier": 1,
+                "task_acks_late": True,
+                "task_reject_on_worker_lost": True,
+                "visibility_timeout_seconds": visibility_timeout_seconds,
+            },
+            "scenario": scenario,
+            "coverage": {
+                "redis_broker_delivery": True,
+                "celery_worker_processes": True,
+                "forced_worker_loss_after_complete_data": True,
+                "same_task_broker_redelivery": True,
+                "durable_outcome_unknown_recovery": True,
+                "duplicate_smtp_transaction_prevented": True,
+                "production_daemon_supervisor": False,
+                "target_provider": False,
+                "source_artifact_provenance": False,
+            },
+        }
+        _assert_evidence_safe(evidence, settings=settings)
+        rendered = json.dumps(
+            evidence,
+            ensure_ascii=False,
+            indent=2,
+            sort_keys=True,
+        ).encode("utf-8") + b"\n"
+        if len(rendered) > MAX_EVIDENCE_BYTES:
+            raise AcceptanceError("Celery-redelivery evidence exceeds its size limit")
+        return evidence
+    finally:
+        if database is not None:
+            database.engine.dispose()
+        shutil.rmtree(runtime_root, ignore_errors=True)
+
+
+def main(argv: list[str] | None = None) -> int:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("--fixture", type=Path, default=DEFAULT_FIXTURE)
+    parser.add_argument("--compose-file", type=Path, default=DEFAULT_COMPOSE_FILE)
+    parser.add_argument("--redis-port", type=int)
+    parser.add_argument(
+        "--visibility-timeout-seconds",
+        type=lambda value: _positive_int(value, label="visibility timeout"),
+        default=os.environ.get(
+            "GOVOPLAN_CAMPAIGN_TEST_REDIS_VISIBILITY_TIMEOUT_SECONDS",
+            "3",
+        ),
+    )
+    parser.add_argument(
+        "--timeout-seconds",
+        type=lambda value: _positive_int(value, label="timeout"),
+        default=60,
+    )
+    parser.add_argument("--evidence", type=Path)
+    args = parser.parse_args(argv)
+
+    try:
+        settings = TestbedSettings.from_environment()
+        settings.assert_local_testbed()
+        settings = replace(
+            settings,
+            provider_timeout_seconds=args.timeout_seconds,
+        )
+        with isolated_redis_broker(
+            compose_file=args.compose_file.resolve(),
+            timeout_seconds=args.timeout_seconds,
+            requested_port=args.redis_port,
+        ) as redis_url:
+            evidence = _bootstrap_and_run(
+                settings=settings,
+                fixture_path=args.fixture.resolve(),
+                redis_url=redis_url,
+                visibility_timeout_seconds=args.visibility_timeout_seconds,
+            )
+        rendered = json.dumps(
+            evidence,
+            ensure_ascii=False,
+            indent=2,
+            sort_keys=True,
+        ) + "\n"
+        if args.evidence:
+            args.evidence.parent.mkdir(parents=True, exist_ok=True)
+            args.evidence.write_text(rendered, encoding="utf-8")
+        else:
+            sys.stdout.write(rendered)
+        return 0
+    except AcceptanceError as exc:
+        print(f"Campaign Celery-redelivery acceptance failed: {exc}", file=sys.stderr)
+        return 1
+    except Exception as exc:
+        print(
+            "Campaign Celery-redelivery acceptance failed unexpectedly "
+            f"({type(exc).__name__}); inspect local service logs.",
+            file=sys.stderr,
+        )
+        return 1
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())
diff --git a/tests/test_celery_redelivery_acceptance.py b/tests/test_celery_redelivery_acceptance.py
new file mode 100644
index 0000000..0dc161e
--- /dev/null
+++ b/tests/test_celery_redelivery_acceptance.py
@@ -0,0 +1,286 @@
+from __future__ import annotations
+
+import importlib.util
+import json
+from pathlib import Path
+from types import SimpleNamespace
+import sys
+import tempfile
+from unittest import mock
+
+import pytest
+
+
+REPOSITORY_ROOT = Path(__file__).resolve().parents[1]
+RUNNER_PATH = (
+    REPOSITORY_ROOT
+    / "dev"
+    / "mail-testbed"
+    / "run_celery_redelivery_acceptance.py"
+)
+COMPOSE_PATH = REPOSITORY_ROOT / "dev" / "mail-testbed" / "docker-compose.yml"
+FIXTURE_PATH = REPOSITORY_ROOT / "examples" / "greenmail-delivery" / "campaign.json"
+TASK_ID = "12345678-1234-4234-8234-123456789abc"
+
+
+def _load_runner():
+    spec = importlib.util.spec_from_file_location(
+        "govoplan_campaign_celery_redelivery_acceptance",
+        RUNNER_PATH,
+    )
+    assert spec is not None and spec.loader is not None
+    module = importlib.util.module_from_spec(spec)
+    sys.modules[spec.name] = module
+    spec.loader.exec_module(module)
+    return module
+
+
+runner = _load_runner()
+
+
+class _Response:
+    def __init__(self, status_code: int, payload: dict) -> None:
+        self.status_code = status_code
+        self._payload = payload
+
+    def json(self) -> dict:
+        return self._payload
+
+
+class _Client:
+    def post(self, path: str, **_kwargs) -> _Response:
+        assert path.endswith("/queue")
+        return _Response(
+            200,
+            {
+                "queued_count": 1,
+                "skipped_count": 0,
+                "blocked_count": 0,
+                "enqueued_count": 1,
+                "delivery_mode": "worker_queue",
+                "worker_queue_available": True,
+                "dry_run": False,
+            },
+        )
+
+    def get(self, path: str, **_kwargs) -> _Response:
+        assert path.endswith("/report")
+        return _Response(
+            200,
+            {
+                "cards": {
+                    "jobs_total": 1,
+                    "outcome_unknown": 1,
+                    "needs_attention": 1,
+                },
+                "status_counts": {
+                    "send": {"outcome_unknown": 1},
+                    "imap": {"pending": 1},
+                },
+            },
+        )
+
+
+class _Endpoint:
+    host = "127.0.0.1"
+    port = 4025
+
+    def __init__(self) -> None:
+        self.release_count = 0
+
+    def wait_for_data(self, _timeout_seconds: int) -> bool:
+        return True
+
+    def release_held_connection(self) -> None:
+        self.release_count += 1
+
+    def evidence(self) -> dict[str, int]:
+        return {
+            "connection_count": 1,
+            "accepted_rcpt_commands": 1,
+            "refused_rcpt_commands": 0,
+            "data_transactions": 1,
+        }
+
+
+def _settings():
+    return runner.TestbedSettings(
+        smtp_host="127.0.0.1",
+        smtp_port=3025,
+        imap_host="127.0.0.1",
+        imap_port=3143,
+        username="campaign-test@govoplan.test",
+        password="local-test-password",
+        sender="campaign-test@govoplan.test",
+        recipient="campaign-test@govoplan.test",
+        sent_folder="Sent",
+        provider_timeout_seconds=5,
+    )
+
+
+def test_compose_redis_is_isolated_durable_and_health_checked() -> None:
+    compose = COMPOSE_PATH.read_text(encoding="utf-8")
+
+    assert "redis:7-alpine" in compose
+    assert '"--appendonly", "yes"' in compose
+    assert "127.0.0.1:${GOVOPLAN_CAMPAIGN_TEST_REDIS_PORT:-36379}:6379" in compose
+    assert 'test: ["CMD", "redis-cli", "ping"]' in compose
+    assert "campaign-redis-data:/data" in compose
+
+
+def test_compose_lifecycle_targets_only_isolated_redis_service() -> None:
+    up = runner._compose_command(
+        compose_file=COMPOSE_PATH,
+        project_name="govoplan-campaign-redelivery-test",
+        operation="up",
+    )
+    down = runner._compose_command(
+        compose_file=COMPOSE_PATH,
+        project_name="govoplan-campaign-redelivery-test",
+        operation="down",
+    )
+
+    assert up[-3:] == ["up", "--detach", "redis"]
+    assert down[-3:] == ["down", "--volumes", "--remove-orphans"]
+    assert "greenmail" not in up
+    assert "--project-name" in up
+
+
+def test_worker_bootstrap_uses_real_late_ack_solo_celery_worker() -> None:
+    source = runner.WORKER_BOOTSTRAP
+
+    assert "celery.worker_main" in source
+    assert '"--pool=solo"' in source
+    assert '"--queues=send_email"' in source
+    assert '"visibility_timeout"' in source
+    assert '"polling_interval"' in source
+    assert "send_email.run" not in source
+
+
+def test_worker_log_projection_matches_redelivered_task_without_retaining_id() -> None:
+    with tempfile.TemporaryDirectory() as temporary_directory:
+        log_path = Path(temporary_directory) / "worker.log"
+        log_path.write_text(
+            "\n".join(
+                [
+                    f"Task govoplan.campaigns.send_email[{TASK_ID}] received",
+                    f"Task govoplan.campaigns.send_email[{TASK_ID}] succeeded in 0.1s",
+                ]
+            ),
+            encoding="utf-8",
+        )
+        with log_path.open("ab") as handle:
+            worker = runner.WorkerProcess(
+                process=SimpleNamespace(),
+                log_path=log_path,
+                log_handle=handle,
+            )
+
+            assert worker.received_task_ids() == (TASK_ID,)
+            assert worker.succeeded_task_ids() == (TASK_ID,)
+
+
+def test_queue_projection_fails_closed_if_no_task_was_published() -> None:
+    with pytest.raises(runner.AcceptanceError, match="one Celery task"):
+        runner._queue_evidence(
+            {
+                "queued_count": 1,
+                "skipped_count": 0,
+                "blocked_count": 0,
+                "enqueued_count": 0,
+                "delivery_mode": "database_queue",
+                "worker_queue_available": False,
+                "dry_run": False,
+            }
+        )
+
+
+def test_redelivery_orchestration_requires_same_task_and_no_second_smtp_effect(
+    monkeypatch,
+) -> None:
+    first_worker = mock.Mock()
+    first_worker.received_task_ids.return_value = (TASK_ID,)
+    replacement_worker = mock.Mock()
+    replacement_worker.received_task_ids.return_value = (TASK_ID,)
+    workers = iter([first_worker, replacement_worker])
+    endpoint = _Endpoint()
+    durable_states = iter(
+        [
+            {
+                "job_count": 1,
+                "send_status_counts": {"sending": 1},
+                "attempt_status_counts": {"smtp_in_progress": 1},
+                "unfinished_attempt_count": 1,
+            },
+            {
+                "job_count": 1,
+                "send_status_counts": {"outcome_unknown": 1},
+                "attempt_status_counts": {"outcome_unknown": 1},
+                "unfinished_attempt_count": 0,
+            },
+        ]
+    )
+    prepared = SimpleNamespace(
+        campaign_id="campaign-internal",
+        version_id="version-internal",
+        public_evidence=lambda: {
+            "validation": {"ok": True},
+            "build": {"built_count": 1},
+            "campaign_mail_boundary": {
+                "profile_reference_only": True,
+                "smtp_revision_frozen": True,
+                "imap_revision_frozen": True,
+                "resolved_transport_material_present": False,
+            },
+        },
+    )
+
+    monkeypatch.setattr(runner, "create_mail_profile", lambda *args, **kwargs: "profile-internal")
+    monkeypatch.setattr(runner, "prepare_campaign_scenario", lambda *args, **kwargs: prepared)
+    monkeypatch.setattr(runner, "_start_worker", lambda *args, **kwargs: next(workers))
+    monkeypatch.setattr(runner, "_wait_for_worker_ready", lambda *args, **kwargs: None)
+    received = iter([TASK_ID, TASK_ID])
+    monkeypatch.setattr(runner, "_wait_for_received_task", lambda *args, **kwargs: next(received))
+    monkeypatch.setattr(runner, "_wait_for_task_success", lambda *args, **kwargs: None)
+    monkeypatch.setattr(runner, "_kill_worker", lambda *args, **kwargs: -9)
+    monkeypatch.setattr(runner, "_stop_worker", lambda *args, **kwargs: None)
+    monkeypatch.setattr(
+        runner,
+        "_wait_for_broker_drained",
+        lambda *args, **kwargs: runner.RedisBrokerState(0, 0, 0),
+    )
+
+    evidence = runner.execute_redelivery_scenario(
+        _Client(),
+        {"Authorization": "not-retained"},
+        fixture_path=FIXTURE_PATH,
+        settings=_settings(),
+        endpoint=endpoint,
+        redis_url="redis://127.0.0.1:36379/0",
+        runtime_root=Path("/not-used"),
+        snapshot_probe=lambda _version_id: ({}, {}),
+        audit_probe=lambda _campaign_id, _version_id: {
+            "campaign.created": 1,
+            "campaign.validated": 1,
+            "campaign.messages_built": 1,
+            "campaign.queued": 1,
+        },
+        delivery_probe=lambda _campaign_id, _version_id: next(durable_states),
+    )
+
+    assert evidence["broker"] == {
+        "transport": "redis",
+        "same_task_identity_redelivered": True,
+        "first_worker_received_count": 1,
+        "replacement_worker_received_count": 1,
+        "queue_depth": 0,
+        "unacked_hash_count": 0,
+        "unacked_index_count": 0,
+    }
+    assert evidence["protocol"]["connection_count"] == 1
+    assert evidence["protocol"]["data_transactions"] == 1
+    assert evidence["recovered_durable_state"]["send_status_counts"] == {
+        "outcome_unknown": 1
+    }
+    assert TASK_ID not in json.dumps(evidence, sort_keys=True)
+    assert endpoint.release_count >= 1