fix(engine): honour backoff timing + don't double-count Proxmox storage

- RunRunner returns early for a waiting run whose next_attempt_at is in the
  future, so stale/duplicate jobs can't bypass backoff.
- RegisterCapacity takes the largest VM-capable datastore instead of summing
  overlapping pools (local + local-lvm), preventing placement overcommit.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/Provisioning/RunRunner.php

@@ -45,6 +45,13 @@ class RunRunner
             return;
         }
 
+        // Honour backoff: a stale/duplicate job must not run a waiting run early.
+        if ($run->status === ProvisioningRun::STATUS_WAITING
+            && $run->next_attempt_at !== null
+            && $run->next_attempt_at->isFuture()) {
+            return;
+        }
+
         // started_at marks when the current step began (drives the timeout).
         if ($run->started_at === null || $run->status === ProvisioningRun::STATUS_PENDING) {
             $run->started_at ??= now();

app/Provisioning/Steps/Host/RegisterCapacity.php

@@ -32,7 +32,18 @@ class RegisterCapacity extends HostStep
 
         $cores = (int) ($status['cpuinfo']['cpus'] ?? 0);
         $ramMb = (int) round((int) ($status['memory']['total'] ?? 0) / 1048576);
-        $totalGb = (int) round(array_sum(array_column($storage, 'total')) / 1073741824);
+
+        // Proxmox lists overlapping pools (e.g. local + local-lvm on one disk).
+        // Take the largest VM-capable datastore instead of summing, so shared
+        // backing storage is never double-counted and placement can't overcommit.
+        $allocatable = array_filter($storage, function ($s) {
+            $content = (string) ($s['content'] ?? '');
+
+            return str_contains($content, 'images') || str_contains($content, 'rootdir');
+        });
+        $pool = $allocatable ?: $storage;
+        $totalBytes = $pool === [] ? 0 : max(array_map(fn ($s) => (int) ($s['total'] ?? 0), $pool));
+        $totalGb = (int) round($totalBytes / 1073741824);
 
         $host->update([
             'cpu_cores' => $cores,

app/Services/Proxmox/FakeProxmoxClient.php

@@ -20,7 +20,8 @@ class FakeProxmoxClient implements ProxmoxClient
 
     /** @var array<int, array<string, mixed>> */
     public array $storage = [
-        ['storage' => 'local-lvm', 'type' => 'lvmthin', 'total' => 1099511627776], // 1 TiB
+        ['storage' => 'local', 'type' => 'dir', 'content' => 'iso,vztmpl,backup', 'total' => 1099511627776],
+        ['storage' => 'local-lvm', 'type' => 'lvmthin', 'content' => 'images,rootdir', 'total' => 1099511627776], // 1 TiB
     ];
 
     public function forHost(Host $host): static

tests/Feature/Provisioning/HostOnboardingEndToEndTest.php

@@ -31,6 +31,9 @@ it('drives a fresh host all the way to active (mocked)', function () {
         if (in_array($run->status, ['completed', 'failed'], true)) {
             break;
         }
+        if ($run->next_attempt_at?->isFuture()) {
+            $run->update(['next_attempt_at' => now()]); // simulate the scheduler waking a due run
+        }
         $runner->advance($run);
     }
 
@@ -73,6 +76,9 @@ it('does not duplicate external resources when a step re-runs after a crash', fu
     // WireGuard step and replaying it — the breadcrumb must prevent duplicates.
     for ($i = 0; $i < 6; $i++) {
         $run->refresh();
+        if ($run->next_attempt_at?->isFuture()) {
+            $run->update(['next_attempt_at' => now()]);
+        }
         $runner->advance($run);
     }
     $run->refresh();

tests/Feature/Provisioning/RunRunnerTest.php

@@ -86,7 +86,9 @@ it('polls without consuming the retry budget', function () {
     app(RunRunner::class)->advance($run);
     expect($run->fresh()->status)->toBe('waiting')->and($run->fresh()->attempt)->toBe(0);
 
-    // A second poll must not fail the run even with max_attempts = 1.
+    // Make the run due again, then poll a second time: still not failed even
+    // with max_attempts = 1 (polls don't consume the retry budget).
+    $run->update(['next_attempt_at' => now()->subSecond()]);
     app(RunRunner::class)->advance($run->fresh());
     expect($run->fresh()->status)->toBe('waiting')->and($run->fresh()->attempt)->toBe(0);
 });