(feature) Add cancellable backup runs and clearer dry-run logs

Add a cancel action for queued and running backup runs. Queued runs are
cancelled immediately, while running runs are marked for cancellation and
the worker terminates the active rsync process group.

Make dry-run log paths run-specific and add a defensive default dry-run
timeout so stuck dry-runs do not remain running indefinitely.

Remove rsync exit codes from run overview tables while keeping detailed
diagnostics available on the run detail payload.

src/pobsync/commands/run_scheduled.py

@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 from pathlib import Path
-from typing import Any
+from typing import Any, Callable
 
 from ..config.source import ConfigSource, FileConfigSource
 from ..errors import ConfigError
@@ -21,6 +21,15 @@ from ..snapshot_meta import read_snapshot_meta
 from ..util import ensure_dir, realpath_startswith, sanitize_host, write_yaml_atomic
 
 
+DEFAULT_DRY_RUN_TIMEOUT_SECONDS = 900
+
+
+def dry_run_log_path(host: str, run_id: int | None = None) -> Path:
+    host = sanitize_host(host)
+    run_dir = f"run-{run_id}" if run_id is not None else "adhoc"
+    return Path(f"/tmp/pobsync-dryrun/{host}/{run_dir}/rsync.log")
+
+
 def _read_log_tail(log_path: Path, *, max_lines: int = 40) -> list[str]:
     try:
         lines = log_path.read_text(encoding="utf-8", errors="replace").splitlines()
@@ -96,6 +105,8 @@ def run_scheduled(
     prune_max_delete: int | None = None,
     prune_protect_bases: bool = False,
     config_source: ConfigSource | None = None,
+    run_id: int | None = None,
+    cancel_check: Callable[[], bool] | None = None,
 ) -> dict[str, Any]:
 
     host = sanitize_host(host)
@@ -149,9 +160,10 @@ def run_scheduled(
     # DRY RUN
     # ------------------------------------------------------------
     if dry_run:
-        dest = f"/tmp/pobsync-dryrun/{host}/"
-        dryrun_log = Path(f"/tmp/pobsync-dryrun/{host}/rsync.log")
+        dryrun_log = dry_run_log_path(host, run_id=run_id)
+        dest = str(dryrun_log.parent) + "/"
         dryrun_log.unlink(missing_ok=True)
+        effective_timeout_seconds = timeout_seconds or DEFAULT_DRY_RUN_TIMEOUT_SECONDS
 
         cmd = build_rsync_command(
             rsync_binary=str(rsync_binary),
@@ -161,13 +173,18 @@ def run_scheduled(
             dest=dest,
             link_dest=link_dest,
             dry_run=True,
-            timeout_seconds=timeout_seconds,
+            timeout_seconds=effective_timeout_seconds,
             bwlimit_kbps=bwlimit_kbps,
             extra_excludes=list(excludes),
             extra_includes=list(includes),
         )
 
-        result = run_rsync(cmd, log_path=dryrun_log, timeout_seconds=timeout_seconds)
+        result = run_rsync(
+            cmd,
+            log_path=dryrun_log,
+            timeout_seconds=effective_timeout_seconds,
+            cancel_check=cancel_check,
+        )
         log_tail = _read_log_tail(dryrun_log)
 
         return {
@@ -176,6 +193,8 @@ def run_scheduled(
             "host": host,
             "base": str(base_dir) if base_dir else None,
             "log": str(dryrun_log),
+            "cancelled": result.cancelled,
+            "timeout_seconds": effective_timeout_seconds,
             "ssh_credential": cfg.get("ssh_credential"),
             "rsync": {
                 "exit_code": result.exit_code,
@@ -242,13 +261,13 @@ def run_scheduled(
         log_path.touch(exist_ok=True)
         write_yaml_atomic(meta_path, meta)
 
-        result = run_rsync(cmd, log_path=log_path, timeout_seconds=timeout_seconds)
+        result = run_rsync(cmd, log_path=log_path, timeout_seconds=timeout_seconds, cancel_check=cancel_check)
 
         end_ts = utc_now()
         meta["ended_at"] = format_iso_z(end_ts)
         meta["duration_seconds"] = int((end_ts - ts).total_seconds())
         meta["rsync"]["exit_code"] = result.exit_code
-        meta["status"] = "success" if result.exit_code == 0 else "failed"
+        meta["status"] = "cancelled" if result.cancelled else ("success" if result.exit_code == 0 else "failed")
         write_yaml_atomic(meta_path, meta)
 
         if not log_path.exists():
@@ -270,6 +289,7 @@ def run_scheduled(
                 "host": host,
                 "snapshot": str(incomplete_dir),
                 "status": meta["status"],
+                "cancelled": result.cancelled,
                 "log": str(log_path),
                 "ssh_credential": cfg.get("ssh_credential"),
                 "rsync": {

src/pobsync/rsync.py

@@ -1,16 +1,20 @@
 from __future__ import annotations
 
+import os
+import signal
 import shlex
 import subprocess
+import time
 from dataclasses import dataclass
 from pathlib import Path
-from typing import Sequence
+from typing import Callable, Sequence
 
 
 @dataclass(frozen=True)
 class RsyncResult:
     exit_code: int
     command: list[str]
+    cancelled: bool = False
 
 
 def build_ssh_command(ssh_cfg: dict) -> list[str]:
@@ -66,7 +70,12 @@ def build_rsync_command(
 
 
 
-def run_rsync(command: list[str], log_path: Path, timeout_seconds: int) -> RsyncResult:
+def run_rsync(
+    command: list[str],
+    log_path: Path,
+    timeout_seconds: int,
+    cancel_check: Callable[[], bool] | None = None,
+) -> RsyncResult:
     """
     Run rsync and always write stdout/stderr to log_path.
 
@@ -77,17 +86,33 @@ def run_rsync(command: list[str], log_path: Path, timeout_seconds: int) -> Rsync
     # Ensure the file exists early.
     log_path.touch(exist_ok=True)
 
-    try:
-        with log_path.open("ab") as f:
-            p = subprocess.run(
-                command,
-                stdout=f,
-                stderr=subprocess.STDOUT,
-                timeout=timeout_seconds if timeout_seconds > 0 else None,
-            )
-        return RsyncResult(exit_code=p.returncode, command=command)
-    except subprocess.TimeoutExpired as e:
-        # Log timeout info and return a non-zero exit code.
     with log_path.open("ab") as f:
+        process = subprocess.Popen(command, stdout=f, stderr=subprocess.STDOUT, start_new_session=True)
+        started = time.monotonic()
+        while True:
+            exit_code = process.poll()
+            if exit_code is not None:
+                return RsyncResult(exit_code=exit_code, command=command)
+
+            if cancel_check is not None and cancel_check():
+                _terminate_process_group(process)
+                f.write(b"\n[pobsync] rsync cancelled\n")
+                return RsyncResult(exit_code=130, command=command, cancelled=True)
+
+            if timeout_seconds > 0 and time.monotonic() - started >= timeout_seconds:
+                _terminate_process_group(process)
                 f.write(b"\n[pobsync] rsync timed out\n")
                 return RsyncResult(exit_code=124, command=command)
+
+            time.sleep(1)
+
+
+def _terminate_process_group(process: subprocess.Popen) -> None:
+    try:
+        os.killpg(process.pid, signal.SIGTERM)
+        process.wait(timeout=10)
+    except ProcessLookupError:
+        return
+    except subprocess.TimeoutExpired:
+        os.killpg(process.pid, signal.SIGKILL)
+        process.wait(timeout=10)

src/pobsync_backend/backup_runner.py

@@ -5,7 +5,7 @@ from pathlib import Path
 from django.db import transaction
 from django.utils import timezone
 
-from pobsync.commands.run_scheduled import run_scheduled
+from pobsync.commands.run_scheduled import dry_run_log_path, run_scheduled
 from pobsync_backend.config_source import DjangoConfigSource
 from pobsync_backend.models import BackupRun, HostConfig
 from pobsync_backend.retention import run_sql_retention_apply
@@ -47,7 +47,8 @@ def execute_backup_run(
 ) -> BackupRun:
     run.status = BackupRun.Status.RUNNING
     run.started_at = run.started_at or timezone.now()
-    run.save(update_fields=["status", "started_at"])
+    run.result = _running_result(run=run, dry_run=bool(dry_run))
+    run.save(update_fields=["status", "started_at", "result"])
 
     try:
         result = run_scheduled(
@@ -56,14 +57,26 @@ def execute_backup_run(
             dry_run=bool(dry_run),
             prune=False,
             config_source=DjangoConfigSource(),
+            run_id=run.id,
+            cancel_check=lambda: _run_cancel_requested(run.id),
         )
     except Exception as exc:
-        run.status = BackupRun.Status.FAILED
+        run.refresh_from_db()
+        run.status = BackupRun.Status.CANCELLED if run.status == BackupRun.Status.CANCELLED else BackupRun.Status.FAILED
         run.ended_at = timezone.now()
-        run.result = {"ok": False, "error": str(exc), "type": type(exc).__name__}
+        run.result = {
+            **(run.result if isinstance(run.result, dict) else {}),
+            "ok": False,
+            "error": str(exc),
+            "type": type(exc).__name__,
+        }
         run.save(update_fields=["status", "ended_at", "result"])
         raise
 
+    run.refresh_from_db()
+    if result.get("cancelled") or run.status == BackupRun.Status.CANCELLED:
+        run.status = BackupRun.Status.CANCELLED
+    else:
         run.status = BackupRun.Status.SUCCESS if result.get("ok") else BackupRun.Status.FAILED
     run.ended_at = timezone.now()
     run.snapshot_path = str(result.get("snapshot") or "")
@@ -146,3 +159,18 @@ def requested_options(run: BackupRun) -> dict[str, object]:
     if not isinstance(requested, dict):
         return {}
     return requested
+
+
+def _running_result(*, run: BackupRun, dry_run: bool) -> dict[str, object]:
+    result = dict(run.result) if isinstance(run.result, dict) else {}
+    execution = {
+        "started_at": (run.started_at or timezone.now()).isoformat(),
+    }
+    if dry_run:
+        execution["log"] = str(dry_run_log_path(run.host.host, run_id=run.id))
+    result["execution"] = execution
+    return result
+
+
+def _run_cancel_requested(run_id: int) -> bool:
+    return BackupRun.objects.filter(id=run_id, status=BackupRun.Status.CANCELLED).exists()

src/pobsync_backend/templates/pobsync_backend/dashboard.html

@@ -86,7 +86,6 @@
           <th>Started</th>
           <th>Ended</th>
           <th>Snapshot</th>
-          <th>Rsync</th>
         </tr>
       </thead>
       <tbody>
@@ -97,10 +96,9 @@
             <td>{{ run.started_at|default:"" }}</td>
             <td>{{ run.ended_at|default:"" }}</td>
             <td>{% if run.snapshot %}<a href="{% url 'snapshot_detail' run.snapshot.id %}">{{ run.snapshot.dirname }}</a>{% else %}<span class="muted">{{ run.snapshot_path }}</span>{% endif %}</td>
-            <td>{{ run.rsync_exit_code|default:"" }}</td>
           </tr>
         {% empty %}
-          <tr><td colspan="6" class="muted">No backup runs recorded yet.</td></tr>
+          <tr><td colspan="5" class="muted">No backup runs recorded yet.</td></tr>
         {% endfor %}
       </tbody>
     </table>

src/pobsync_backend/templates/pobsync_backend/host_detail.html

@@ -175,7 +175,6 @@
           <th>Ended</th>
           <th>Snapshot</th>
           <th>Base</th>
-          <th>Rsync</th>
         </tr>
       </thead>
       <tbody>
@@ -186,10 +185,9 @@
             <td>{{ run.ended_at|default:"" }}</td>
             <td>{% if run.snapshot %}<a href="{% url 'snapshot_detail' run.snapshot.id %}">{{ run.snapshot.dirname }}</a>{% else %}<span class="muted">{{ run.snapshot_path }}</span>{% endif %}</td>
             <td>{{ run.base_path|default:"" }}</td>
-            <td>{{ run.rsync_exit_code|default:"" }}</td>
           </tr>
         {% empty %}
-          <tr><td colspan="6" class="muted">No backup runs recorded for this host.</td></tr>
+          <tr><td colspan="5" class="muted">No backup runs recorded for this host.</td></tr>
         {% endfor %}
       </tbody>
     </table>

src/pobsync_backend/templates/pobsync_backend/run_detail.html

@@ -7,6 +7,12 @@
 
   <section class="actions" aria-label="Run actions">
     <a class="button-link" href="{% url 'host_detail' run.host.host %}">Back to host</a>
+    {% if can_cancel %}
+      <form method="post" action="{% url 'cancel_run' run.id %}">
+        {% csrf_token %}
+        <button type="submit" class="secondary">Cancel run</button>
+      </form>
+    {% endif %}
   </section>
 
   <section class="grid" aria-label="Run summary">

src/pobsync_backend/templates/pobsync_backend/snapshot_detail.html

@@ -47,7 +47,6 @@
           <th>Status</th>
           <th>Started</th>
           <th>Ended</th>
-          <th>Rsync</th>
         </tr>
       </thead>
       <tbody>
@@ -57,10 +56,9 @@
             <td><span class="status {{ run.status }}">{{ run.status }}</span></td>
             <td>{{ run.started_at|default:"" }}</td>
             <td>{{ run.ended_at|default:"" }}</td>
-            <td>{{ run.rsync_exit_code|default:"" }}</td>
           </tr>
         {% empty %}
-          <tr><td colspan="5" class="muted">No backup runs linked to this snapshot.</td></tr>
+          <tr><td colspan="4" class="muted">No backup runs linked to this snapshot.</td></tr>
         {% endfor %}
       </tbody>
     </table>

src/pobsync_backend/tests/test_backup_worker.py

@@ -48,7 +48,10 @@ class BackupWorkerTests(TestCase):
             run = queue_backup_run(host=host)
 
             with patch("pobsync_backend.backup_runner.run_scheduled") as run_scheduled:
-                run_scheduled.return_value = {
+                def fake_run_scheduled(**kwargs):
+                    run.refresh_from_db()
+                    self.assertIn("execution", run.result)
+                    return {
                         "ok": True,
                         "dry_run": False,
                         "host": host.host,
@@ -56,14 +59,76 @@ class BackupWorkerTests(TestCase):
                         "base": None,
                         "rsync": {"exit_code": 0},
                     }
+
+                run_scheduled.side_effect = fake_run_scheduled
                 count = Command()._run_once(prefix=Path(tmp) / "home")
+                run_scheduled.assert_called_once()
 
         self.assertEqual(count, 1)
+        self.assertEqual(run_scheduled.call_args.kwargs["run_id"], run.id)
         run.refresh_from_db()
         self.assertEqual(run.status, BackupRun.Status.SUCCESS)
         self.assertEqual(SnapshotRecord.objects.count(), 1)
         self.assertEqual(run.snapshot, SnapshotRecord.objects.get())
 
+    def test_worker_records_dry_run_log_path_while_running(self) -> None:
+        with TemporaryDirectory() as tmp:
+            GlobalConfig.objects.create(name="default", backup_root=str(Path(tmp) / "backups"))
+            host = HostConfig.objects.create(host="web-01", address="web-01.example.test")
+            run = queue_backup_run(host=host, dry_run=True)
+
+            with patch("pobsync_backend.backup_runner.run_scheduled") as run_scheduled:
+                def fake_run_scheduled(**kwargs):
+                    run.refresh_from_db()
+                    self.assertEqual(
+                        run.result["execution"]["log"],
+                        f"/tmp/pobsync-dryrun/{host.host}/run-{run.id}/rsync.log",
+                    )
+                    return {
+                        "ok": True,
+                        "dry_run": True,
+                        "host": host.host,
+                        "base": None,
+                        "log": run.result["execution"]["log"],
+                        "rsync": {"exit_code": 0},
+                    }
+
+                run_scheduled.side_effect = fake_run_scheduled
+                count = Command()._run_once(prefix=Path(tmp) / "home")
+
+        self.assertEqual(count, 1)
+        run.refresh_from_db()
+        self.assertEqual(run.status, BackupRun.Status.SUCCESS)
+        self.assertEqual(run.result["log"], f"/tmp/pobsync-dryrun/{host.host}/run-{run.id}/rsync.log")
+
+    def test_worker_preserves_cancelled_status_from_running_run(self) -> None:
+        with TemporaryDirectory() as tmp:
+            GlobalConfig.objects.create(name="default", backup_root=str(Path(tmp) / "backups"))
+            host = HostConfig.objects.create(host="web-01", address="web-01.example.test")
+            run = queue_backup_run(host=host, dry_run=True)
+
+            with patch("pobsync_backend.backup_runner.run_scheduled") as run_scheduled:
+                def fake_run_scheduled(**kwargs):
+                    BackupRun.objects.filter(id=run.id).update(status=BackupRun.Status.CANCELLED)
+                    self.assertTrue(kwargs["cancel_check"]())
+                    return {
+                        "ok": False,
+                        "dry_run": True,
+                        "cancelled": True,
+                        "host": host.host,
+                        "base": None,
+                        "log": f"/tmp/pobsync-dryrun/{host.host}/run-{run.id}/rsync.log",
+                        "rsync": {"exit_code": 130},
+                    }
+
+                run_scheduled.side_effect = fake_run_scheduled
+                count = Command()._run_once(prefix=Path(tmp) / "home")
+
+        self.assertEqual(count, 1)
+        run.refresh_from_db()
+        self.assertEqual(run.status, BackupRun.Status.CANCELLED)
+        self.assertEqual(run.rsync_exit_code, 130)
+
     def test_worker_returns_zero_without_queued_runs(self) -> None:
         count = Command()._run_once(prefix=Path("/opt/pobsync"))
 

src/pobsync_backend/tests/test_run_scheduled_config_source.py

@@ -50,7 +50,7 @@ class RunScheduledConfigSourceTests(SimpleTestCase):
         run_rsync.assert_called_once()
 
     def test_failed_dry_run_includes_log_tail(self) -> None:
-        def fake_run_rsync(command, log_path, timeout_seconds):
+        def fake_run_rsync(command, log_path, timeout_seconds, cancel_check=None):
             log_path.parent.mkdir(parents=True, exist_ok=True)
             log_path.write_text("Permission denied (publickey).\nrsync error\n", encoding="utf-8")
             return RsyncResult(exit_code=12, command=command)
@@ -68,13 +68,13 @@ class RunScheduledConfigSourceTests(SimpleTestCase):
         self.assertEqual(result["rsync"]["log_tail"], ["Permission denied (publickey).", "rsync error"])
 
     def test_dry_run_clears_previous_log_before_running(self) -> None:
-        def fake_run_rsync(command, log_path, timeout_seconds):
+        def fake_run_rsync(command, log_path, timeout_seconds, cancel_check=None):
             self.assertFalse(log_path.exists())
             log_path.parent.mkdir(parents=True, exist_ok=True)
             log_path.write_text("current run only\n", encoding="utf-8")
             return RsyncResult(exit_code=0, command=command)
 
-        old_log = Path("/tmp/pobsync-dryrun/web-01/rsync.log")
+        old_log = Path("/tmp/pobsync-dryrun/web-01/adhoc/rsync.log")
         old_log.parent.mkdir(parents=True, exist_ok=True)
         old_log.write_text("old failure\n", encoding="utf-8")
 
@@ -89,6 +89,47 @@ class RunScheduledConfigSourceTests(SimpleTestCase):
         self.assertTrue(result["ok"])
         self.assertEqual(result["rsync"]["log_tail"], ["current run only"])
 
+    def test_dry_run_uses_run_specific_log_path_and_default_timeout(self) -> None:
+        def fake_run_rsync(command, log_path, timeout_seconds, cancel_check=None):
+            self.assertEqual(log_path, Path("/tmp/pobsync-dryrun/web-01/run-42/rsync.log"))
+            self.assertEqual(timeout_seconds, 900)
+            log_path.parent.mkdir(parents=True, exist_ok=True)
+            log_path.write_text("run 42\n", encoding="utf-8")
+            return RsyncResult(exit_code=0, command=command)
+
+        with patch("pobsync.commands.run_scheduled.run_rsync", side_effect=fake_run_rsync):
+            result = run_scheduled(
+                prefix=Path("/missing-prefix"),
+                host="web-01",
+                dry_run=True,
+                config_source=FakeConfigSource(),
+                run_id=42,
+            )
+
+        self.assertTrue(result["ok"])
+        self.assertEqual(result["log"], "/tmp/pobsync-dryrun/web-01/run-42/rsync.log")
+        self.assertEqual(result["timeout_seconds"], 900)
+
+    def test_dry_run_reports_cancelled_rsync(self) -> None:
+        def fake_run_rsync(command, log_path, timeout_seconds, cancel_check=None):
+            self.assertTrue(cancel_check())
+            log_path.parent.mkdir(parents=True, exist_ok=True)
+            log_path.write_text("[pobsync] rsync cancelled\n", encoding="utf-8")
+            return RsyncResult(exit_code=130, command=command, cancelled=True)
+
+        with patch("pobsync.commands.run_scheduled.run_rsync", side_effect=fake_run_rsync):
+            result = run_scheduled(
+                prefix=Path("/missing-prefix"),
+                host="web-01",
+                dry_run=True,
+                config_source=FakeConfigSource(),
+                cancel_check=lambda: True,
+            )
+
+        self.assertFalse(result["ok"])
+        self.assertTrue(result["cancelled"])
+        self.assertEqual(result["rsync"]["exit_code"], 130)
+
     def test_successful_real_run_applies_prune_when_requested(self) -> None:
         with TemporaryDirectory() as tmp:
             prefix = Path(tmp) / "home"

src/pobsync_backend/tests/test_views.py

@@ -764,6 +764,44 @@ class ViewTests(TestCase):
         self.assertContains(response, ""ok": true")
         self.assertContains(response, reverse("snapshot_detail", args=[snapshot.id]))
 
+    def test_run_detail_offers_cancel_for_running_run(self) -> None:
+        self.client.force_login(self.staff_user)
+        host = HostConfig.objects.create(host="web-01", address="web-01.example.test")
+        run = BackupRun.objects.create(host=host, status=BackupRun.Status.RUNNING)
+
+        response = self.client.get(reverse("run_detail", args=[run.id]))
+
+        self.assertEqual(response.status_code, 200)
+        self.assertContains(response, "Cancel run")
+        self.assertContains(response, reverse("cancel_run", args=[run.id]))
+
+    def test_cancel_run_marks_queued_run_cancelled(self) -> None:
+        self.client.force_login(self.staff_user)
+        host = HostConfig.objects.create(host="web-01", address="web-01.example.test")
+        run = BackupRun.objects.create(host=host, status=BackupRun.Status.QUEUED)
+
+        response = self.client.post(reverse("cancel_run", args=[run.id]), follow=True)
+
+        self.assertRedirects(response, reverse("run_detail", args=[run.id]))
+        self.assertContains(response, "Cancellation requested")
+        run.refresh_from_db()
+        self.assertEqual(run.status, BackupRun.Status.CANCELLED)
+        self.assertIsNotNone(run.ended_at)
+        self.assertEqual(run.result["cancellation"]["previous_status"], BackupRun.Status.QUEUED)
+
+    def test_cancel_run_requests_running_run_cancellation(self) -> None:
+        self.client.force_login(self.staff_user)
+        host = HostConfig.objects.create(host="web-01", address="web-01.example.test")
+        run = BackupRun.objects.create(host=host, status=BackupRun.Status.RUNNING)
+
+        response = self.client.post(reverse("cancel_run", args=[run.id]), follow=True)
+
+        self.assertRedirects(response, reverse("run_detail", args=[run.id]))
+        run.refresh_from_db()
+        self.assertEqual(run.status, BackupRun.Status.CANCELLED)
+        self.assertIsNone(run.ended_at)
+        self.assertEqual(run.result["cancellation"]["previous_status"], BackupRun.Status.RUNNING)
+
     def test_snapshot_detail_renders_metadata_runs_and_children(self) -> None:
         self.client.force_login(self.staff_user)
         host = HostConfig.objects.create(host="web-01", address="web-01.example.test")

src/pobsync_backend/views.py

@@ -10,6 +10,7 @@ from django.contrib.admin.views.decorators import staff_member_required
 from django.conf import settings
 from django.db.models import Count
 from django.shortcuts import get_object_or_404, redirect, render
+from django.utils import timezone
 from django.views.decorators.http import require_POST
 
 from pobsync.errors import PobsyncError
@@ -348,12 +349,37 @@ def run_detail(request, run_id: int):
     run = get_object_or_404(BackupRun.objects.select_related("host", "snapshot"), id=run_id)
     context = {
         "run": run,
+        "can_cancel": run.status in {BackupRun.Status.QUEUED, BackupRun.Status.RUNNING},
         "requested": run.result.get("requested") if isinstance(run.result, dict) else {},
         "result_json": _pretty_json(run.result),
     }
     return render(request, "pobsync_backend/run_detail.html", context)
 
 
+@staff_member_required
+@require_POST
+def cancel_run(request, run_id: int):
+    run = get_object_or_404(BackupRun.objects.select_related("host"), id=run_id)
+    if run.status not in {BackupRun.Status.QUEUED, BackupRun.Status.RUNNING}:
+        messages.warning(request, f"Run {run.id} is already {run.status}.")
+        return redirect("run_detail", run_id=run.id)
+
+    result = dict(run.result) if isinstance(run.result, dict) else {}
+    result["cancellation"] = {
+        "requested_at": timezone.now().isoformat(),
+        "previous_status": run.status,
+    }
+    update_fields = ["status", "result"]
+    run.status = BackupRun.Status.CANCELLED
+    run.result = result
+    if result["cancellation"]["previous_status"] == BackupRun.Status.QUEUED:
+        run.ended_at = timezone.now()
+        update_fields.append("ended_at")
+    run.save(update_fields=update_fields)
+    messages.success(request, f"Cancellation requested for run {run.id}.")
+    return redirect("run_detail", run_id=run.id)
+
+
 @staff_member_required
 def snapshot_detail(request, snapshot_id: int):
     snapshot = get_object_or_404(

src/pobsync_server/urls.py

@@ -27,6 +27,7 @@ urlpatterns = [
     path("hosts/<str:host>/retention-plan/", views.host_retention_plan, name="host_retention_plan"),
     path("hosts/<str:host>/schedule/", views.edit_host_schedule, name="edit_host_schedule"),
     path("runs/<int:run_id>/", views.run_detail, name="run_detail"),
+    path("runs/<int:run_id>/cancel/", views.cancel_run, name="cancel_run"),
     path("snapshots/<int:snapshot_id>/", views.snapshot_detail, name="snapshot_detail"),
     path("api/", api.api_index),
     path("api/status/", api.status),