diff --git a/app/Http/Controllers/Api/V1/SyncController.php b/app/Http/Controllers/Api/V1/SyncController.php
index 32aa0ef..893d43e 100644
--- a/app/Http/Controllers/Api/V1/SyncController.php
+++ b/app/Http/Controllers/Api/V1/SyncController.php
@@ -3,29 +3,36 @@
 namespace App\Http\Controllers\Api\V1;
 
 use App\Http\Controllers\Controller;
+use App\Models\Feature;
+use App\Models\Inspection;
+use App\Models\Issue;
 use App\Models\Phase;
 use App\Models\ProgressUpdate;
+use App\Models\Project;
 use App\Models\User;
+use Carbon\Carbon;
 use Illuminate\Http\Request;
 use Illuminate\Support\Facades\Validator;
 
 class SyncController extends Controller
 {
     /**
-     * Push a batch of offline mutations. Idempotent by client-generated `uuid`.
-     * Returns a per-operation result (applied | duplicate | conflict | error).
+     * Push a batch of offline mutations. Returns a per-operation result
+     * (applied | duplicate | conflict | error). Never aborts the whole batch.
      *
-     * Milestone 2: supports only progress_update.create (vertical slice).
+     * Identity:
+     *  - create ops → the new record stores the client-generated `uuid` (idempotent).
+     *  - update ops → target identified by `data.id` (server id); last-write-wins.
      */
     public function sync(Request $request)
     {
         $data = $request->validate([
-            'operations'                     => ['required', 'array'],
-            'operations.*.entity'            => ['required', 'string'],
-            'operations.*.op'                => ['required', 'string'],
-            'operations.*.uuid'              => ['required', 'uuid'],
-            'operations.*.data'              => ['required', 'array'],
-            'operations.*.client_updated_at' => ['nullable', 'date'],
+            'operations'                      => ['required', 'array'],
+            'operations.*.entity'             => ['required', 'string'],
+            'operations.*.op'                 => ['required', 'string'],
+            'operations.*.uuid'               => ['required', 'uuid'],
+            'operations.*.data'               => ['required', 'array'],
+            'operations.*.client_updated_at'  => ['nullable', 'date'],
         ]);
 
         $user = $request->user();
@@ -43,59 +50,256 @@ class SyncController extends Controller
         $uuid = $op['uuid'];
 
         try {
-            if ($op['entity'] === 'progress_update' && $op['op'] === 'create') {
-                return $this->progressUpdateCreate($user, $uuid, $op);
-            }
-
-            return $this->error($uuid, 'unsupported entity/op: ' . $op['entity'] . '.' . $op['op']);
+            return match ($op['entity'] . '.' . $op['op']) {
+                'progress_update.create' => $this->progressUpdateCreate($user, $uuid, $op),
+                'inspection.create'      => $this->inspectionCreate($user, $uuid, $op),
+                'issue.create'           => $this->issueCreate($user, $uuid, $op),
+                'issue.update'           => $this->issueUpdate($user, $uuid, $op),
+                'feature.update'         => $this->featureUpdate($user, $uuid, $op),
+                default                  => $this->error($uuid, 'unsupported entity/op: ' . $op['entity'] . '.' . $op['op']),
+            };
         } catch (\Throwable $e) {
             return $this->error($uuid, $e->getMessage());
         }
     }
 
+    // ── progress_update.create ───────────────────────────────────────────────────
+
     private function progressUpdateCreate(User $user, string $uuid, array $op): array
     {
-        // Idempotency: same uuid already applied → duplicate (no-op).
-        $existing = ProgressUpdate::where('uuid', $uuid)->first();
-        if ($existing) {
-            return ['uuid' => $uuid, 'status' => 'duplicate', 'server_id' => $existing->id];
+        if ($existing = ProgressUpdate::where('uuid', $uuid)->first()) {
+            return $this->duplicate($uuid, $existing->id);
         }
 
-        $validator = Validator::make($op['data'], [
+        $v = Validator::make($op['data'], [
             'phase_id' => ['required', 'integer', 'exists:phases,id'],
             'progress' => ['required', 'integer', 'min:0', 'max:100'],
             'comment'  => ['nullable', 'string'],
             'location' => ['nullable', 'array'],
         ]);
-        if ($validator->fails()) {
-            return $this->error($uuid, 'validation: ' . $validator->errors()->first());
+        if ($v->fails()) {
+            return $this->error($uuid, 'validation: ' . $v->errors()->first());
         }
-        $d = $validator->validated();
+        $d = $v->validated();
 
         $phase = Phase::with('project')->findOrFail($d['phase_id']);
-
-        // Authorization: project membership + permission (per-op, never abort the batch).
-        $isMember = $user->can('manage all')
-            || ($phase->project && $phase->project->users()->where('user_id', $user->id)->exists());
-        if (! $isMember || ! $user->can('update progress')) {
+        if (! $this->canAccess($user, $phase->project) || ! $user->can('update progress')) {
             return $this->error($uuid, 'forbidden');
         }
 
         $pu = ProgressUpdate::create([
             'uuid'              => $uuid,
             'phase_id'          => $phase->id,
-            'user_id'           => $user->id,          // server-set, never trust client
+            'user_id'           => $user->id,
             'progress_percent'  => $d['progress'],
             'comment'           => $d['comment'] ?? null,
             'location'          => $d['location'] ?? null,
             'client_updated_at' => $op['client_updated_at'] ?? null,
         ]);
 
-        // Mirror the web behaviour: reflect latest progress on the phase.
         $phase->progress_percent = $d['progress'];
         $phase->save();
 
-        return ['uuid' => $uuid, 'status' => 'applied', 'server_id' => $pu->id];
+        return $this->applied($uuid, $pu->id);
+    }
+
+    // ── inspection.create ──────────────────────────────────────────────────────────
+
+    private function inspectionCreate(User $user, string $uuid, array $op): array
+    {
+        if ($existing = Inspection::where('uuid', $uuid)->first()) {
+            return $this->duplicate($uuid, $existing->id);
+        }
+
+        $v = Validator::make($op['data'], [
+            'feature_id'  => ['required', 'integer', 'exists:features,id'],
+            'template_id' => ['nullable', 'integer', 'exists:inspection_templates,id'],
+            'data'        => ['nullable', 'array'],
+            'status'      => ['nullable', 'string'],
+            'result'      => ['nullable', 'string'],
+            'notes'       => ['nullable', 'string'],
+        ]);
+        if ($v->fails()) {
+            return $this->error($uuid, 'validation: ' . $v->errors()->first());
+        }
+        $d = $v->validated();
+
+        $feature = Feature::with('layer.phase.project')->findOrFail($d['feature_id']);
+        $project = $feature->layer?->phase?->project;
+        if (! $this->canAccess($user, $project) || ! $user->can('create inspections')) {
+            return $this->error($uuid, 'forbidden');
+        }
+
+        $inspection = Inspection::create([
+            'uuid'              => $uuid,
+            'project_id'        => $project->id,
+            'layer_id'          => $feature->layer_id,
+            'feature_id'        => $feature->id,
+            'template_id'       => $d['template_id'] ?? null,
+            'user_id'           => $user->id,
+            'data'              => $d['data'] ?? [],
+            'status'            => $d['status'] ?? 'completed',
+            'result'            => $d['result'] ?? null,
+            'notes'             => $d['notes'] ?? null,
+            'client_updated_at' => $op['client_updated_at'] ?? null,
+        ]);
+
+        return $this->applied($uuid, $inspection->id);
+    }
+
+    // ── issue.create / issue.update ──────────────────────────────────────────────────
+
+    private function issueCreate(User $user, string $uuid, array $op): array
+    {
+        if ($existing = Issue::where('uuid', $uuid)->first()) {
+            return $this->duplicate($uuid, $existing->id);
+        }
+
+        $v = Validator::make($op['data'], [
+            'project_id'  => ['required', 'integer', 'exists:projects,id'],
+            'feature_id'  => ['nullable', 'integer', 'exists:features,id'],
+            'title'       => ['required', 'string', 'max:255'],
+            'description' => ['nullable', 'string'],
+            'priority'    => ['nullable', 'in:' . implode(',', Issue::PRIORITIES)],
+            'status'      => ['nullable', 'in:' . implode(',', Issue::STATUSES)],
+        ]);
+        if ($v->fails()) {
+            return $this->error($uuid, 'validation: ' . $v->errors()->first());
+        }
+        $d = $v->validated();
+
+        $project = Project::find($d['project_id']);
+        if (! $this->canAccess($user, $project) || ! $user->can('create issues')) {
+            return $this->error($uuid, 'forbidden');
+        }
+
+        $issue = Issue::create([
+            'uuid'              => $uuid,
+            'project_id'        => $project->id,
+            'feature_id'        => $d['feature_id'] ?? null,
+            'title'             => $d['title'],
+            'description'       => $d['description'] ?? null,
+            'priority'          => $d['priority'] ?? 'medium',
+            'status'            => $d['status'] ?? 'open',
+            'reported_by'       => $user->id,
+            'client_updated_at' => $op['client_updated_at'] ?? null,
+        ]);
+
+        return $this->applied($uuid, $issue->id);
+    }
+
+    private function issueUpdate(User $user, string $uuid, array $op): array
+    {
+        $v = Validator::make($op['data'], [
+            'id'               => ['required', 'integer', 'exists:issues,id'],
+            'title'            => ['nullable', 'string', 'max:255'],
+            'description'      => ['nullable', 'string'],
+            'priority'         => ['nullable', 'in:' . implode(',', Issue::PRIORITIES)],
+            'status'           => ['nullable', 'in:' . implode(',', Issue::STATUSES)],
+            'assigned_to'      => ['nullable', 'integer', 'exists:users,id'],
+            'resolution_notes' => ['nullable', 'string'],
+        ]);
+        if ($v->fails()) {
+            return $this->error($uuid, 'validation: ' . $v->errors()->first());
+        }
+        $d = $v->validated();
+
+        $issue = Issue::with('project')->findOrFail($d['id']);
+        if (! $this->canAccess($user, $issue->project) || ! $user->can('edit issues')) {
+            return $this->error($uuid, 'forbidden');
+        }
+
+        if ($conflict = $this->conflict($uuid, $issue, $op)) {
+            return $conflict;
+        }
+
+        $issue->fill(collect($d)->except('id')->toArray());
+        if (in_array($issue->status, ['resolved', 'closed'], true) && ! $issue->resolved_at) {
+            $issue->resolved_at = now();
+        }
+        $issue->client_updated_at = $op['client_updated_at'] ?? null;
+        $issue->save();
+
+        return $this->applied($uuid, $issue->id);
+    }
+
+    // ── feature.update ────────────────────────────────────────────────────────────
+
+    private function featureUpdate(User $user, string $uuid, array $op): array
+    {
+        $v = Validator::make($op['data'], [
+            'id'          => ['required', 'integer', 'exists:features,id'],
+            'status'      => ['nullable', 'string'],
+            'progress'    => ['nullable', 'integer', 'min:0', 'max:100'],
+            'responsible' => ['nullable', 'string'],
+        ]);
+        if ($v->fails()) {
+            return $this->error($uuid, 'validation: ' . $v->errors()->first());
+        }
+        $d = $v->validated();
+
+        $feature = Feature::with('layer.phase.project')->findOrFail($d['id']);
+        $project = $feature->layer?->phase?->project;
+        if (! $this->canAccess($user, $project) || ! $user->can('update progress')) {
+            return $this->error($uuid, 'forbidden');
+        }
+
+        if ($conflict = $this->conflict($uuid, $feature, $op)) {
+            return $conflict;
+        }
+
+        $feature->fill(collect($d)->except('id')->toArray());
+        $feature->client_updated_at = $op['client_updated_at'] ?? null;
+        $feature->save();
+
+        // Mirror web behaviour: recompute the phase progress from its features.
+        if ($phase = $feature->layer?->phase) {
+            $phase->progress_percent = (int) round($phase->features()->avg('progress') ?: 0);
+            $phase->save();
+        }
+
+        return $this->applied($uuid, $feature->id);
+    }
+
+    // ── Helpers ──────────────────────────────────────────────────────────────────────
+
+    private function canAccess(User $user, ?Project $project): bool
+    {
+        if (! $project) {
+            return false;
+        }
+        return $user->can('manage all')
+            || $project->users()->where('user_id', $user->id)->exists();
+    }
+
+    /**
+     * Last-write-wins conflict detection: if the server row was updated after the
+     * client's edit, reject with the current server value.
+     */
+    private function conflict(string $uuid, $model, array $op): ?array
+    {
+        if (empty($op['client_updated_at'])) {
+            return null;
+        }
+        $clientAt = Carbon::parse($op['client_updated_at']);
+        if ($model->updated_at && $model->updated_at->gt($clientAt)) {
+            return [
+                'uuid'   => $uuid,
+                'status' => 'conflict',
+                'server' => $model->fresh()->toArray(),
+            ];
+        }
+        return null;
+    }
+
+    private function applied(string $uuid, int $id): array
+    {
+        return ['uuid' => $uuid, 'status' => 'applied', 'server_id' => $id];
+    }
+
+    private function duplicate(string $uuid, int $id): array
+    {
+        return ['uuid' => $uuid, 'status' => 'duplicate', 'server_id' => $id];
     }
 
     private function error(string $uuid, string $message): array
diff --git a/app/Models/Feature.php b/app/Models/Feature.php
index 902fded..6be23ba 100644
--- a/app/Models/Feature.php
+++ b/app/Models/Feature.php
@@ -15,6 +15,7 @@ class Feature extends Model
     protected $fillable = [
         'layer_id', 'name', 'geometry', 'properties', 'template_id',
         'progress', 'status', 'responsible', 'responsible_user_id',
+        'uuid', 'client_updated_at',
     ];
 
     protected $casts = [
diff --git a/app/Models/Inspection.php b/app/Models/Inspection.php
index 0be239b..76b735c 100644
--- a/app/Models/Inspection.php
+++ b/app/Models/Inspection.php
@@ -16,6 +16,7 @@ class Inspection extends Model
     protected $fillable = [
         'project_id', 'layer_id', 'feature_id', 'template_id', 'user_id',
         'data', 'status', 'inspector_user_id', 'completed_at', 'result', 'notes',
+        'uuid', 'client_updated_at',
     ];
 
     protected $casts = [
diff --git a/app/Models/Issue.php b/app/Models/Issue.php
index acedaec..7a774c9 100644
--- a/app/Models/Issue.php
+++ b/app/Models/Issue.php
@@ -16,7 +16,8 @@ class Issue extends Model
     protected $fillable = [
         'project_id', 'feature_id', 'inspection_id',
         'title', 'description', 'status', 'priority',
-        'reported_by', 'assigned_to', 'resolved_at', 'resolution_notes'
+        'reported_by', 'assigned_to', 'resolved_at', 'resolution_notes',
+        'uuid', 'client_updated_at',
     ];
 
     protected $casts = ['resolved_at' => 'datetime'];
diff --git a/database/migrations/2026_06_18_073000_add_sync_fields_to_syncable_tables.php b/database/migrations/2026_06_18_073000_add_sync_fields_to_syncable_tables.php
new file mode 100644
index 0000000..2ca0fef
--- /dev/null
+++ b/database/migrations/2026_06_18_073000_add_sync_fields_to_syncable_tables.php
@@ -0,0 +1,37 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    private array $tables = ['features', 'inspections', 'issues'];
+
+    public function up(): void
+    {
+        foreach ($this->tables as $name) {
+            Schema::table($name, function (Blueprint $table) use ($name) {
+                if (! Schema::hasColumn($name, 'uuid')) {
+                    $table->uuid('uuid')->nullable()->unique()->after('id');
+                }
+                if (! Schema::hasColumn($name, 'client_updated_at')) {
+                    $table->timestamp('client_updated_at')->nullable();
+                }
+            });
+        }
+    }
+
+    public function down(): void
+    {
+        foreach ($this->tables as $name) {
+            Schema::table($name, function (Blueprint $table) use ($name) {
+                foreach (['uuid', 'client_updated_at'] as $col) {
+                    if (Schema::hasColumn($name, $col)) {
+                        $table->dropColumn($col);
+                    }
+                }
+            });
+        }
+    }
+};
diff --git a/tests/Feature/Api/MobileApiTest.php b/tests/Feature/Api/MobileApiTest.php
index 41ba0f5..1a15e36 100644
--- a/tests/Feature/Api/MobileApiTest.php
+++ b/tests/Feature/Api/MobileApiTest.php
@@ -3,7 +3,9 @@
 namespace Tests\Feature\Api;
 
 use App\Models\Feature;
+use App\Models\Inspection;
 use App\Models\InspectionTemplate;
+use App\Models\Issue;
 use App\Models\Layer;
 use App\Models\Phase;
 use App\Models\Project;
@@ -23,8 +25,9 @@ class MobileApiTest extends TestCase
     protected function setUp(): void
     {
         parent::setUp();
-        Permission::findOrCreate('update progress');
-        Permission::findOrCreate('manage all');
+        foreach (['update progress', 'manage all', 'create inspections', 'create issues', 'edit issues'] as $p) {
+            Permission::findOrCreate($p);
+        }
     }
 
     private function makeProject(?User $member = null): Project
@@ -277,4 +280,95 @@ class MobileApiTest extends TestCase
         $this->assertTrue(collect($res->json('templates'))->pluck('name')->contains('Plantilla A'));
         $this->assertNotNull($res->json('templates.0.hash'));
     }
+
+    // ── Push: inspections / issues / features (Milestone 4) ──────────────────────
+
+    public function test_sync_creates_inspection_and_is_idempotent(): void
+    {
+        $user = User::factory()->create();
+        $user->givePermissionTo('create inspections');
+        $project = $this->makeProject($user);
+        $feature = $this->makeFeature($this->makeLayer($this->makePhase($project)));
+        $uuid = (string) Str::uuid();
+
+        Sanctum::actingAs($user, ['mobile-sync']);
+        $payload = ['operations' => [[
+            'entity' => 'inspection', 'op' => 'create', 'uuid' => $uuid,
+            'data' => ['feature_id' => $feature->id, 'data' => ['ok' => true], 'result' => 'pass'],
+        ]]];
+
+        $this->postJson('/api/v1/sync', $payload)->assertOk()->assertJsonPath('results.0.status', 'applied');
+        $this->assertDatabaseHas('inspections', ['uuid' => $uuid, 'feature_id' => $feature->id, 'user_id' => $user->id]);
+
+        $this->postJson('/api/v1/sync', $payload)->assertOk()->assertJsonPath('results.0.status', 'duplicate');
+        $this->assertEquals(1, Inspection::where('uuid', $uuid)->count());
+    }
+
+    public function test_sync_creates_and_updates_an_issue(): void
+    {
+        $user = User::factory()->create();
+        $user->givePermissionTo(['create issues', 'edit issues']);
+        $project = $this->makeProject($user);
+
+        Sanctum::actingAs($user, ['mobile-sync']);
+
+        // create
+        $uuid = (string) Str::uuid();
+        $this->postJson('/api/v1/sync', ['operations' => [[
+            'entity' => 'issue', 'op' => 'create', 'uuid' => $uuid,
+            'data' => ['project_id' => $project->id, 'title' => 'Grieta', 'priority' => 'high'],
+        ]]])->assertOk()->assertJsonPath('results.0.status', 'applied');
+
+        $issue = Issue::where('uuid', $uuid)->firstOrFail();
+        $this->assertEquals('open', $issue->status);
+
+        // update (resolve) → resolved_at set
+        $this->postJson('/api/v1/sync', ['operations' => [[
+            'entity' => 'issue', 'op' => 'update', 'uuid' => (string) Str::uuid(),
+            'data' => ['id' => $issue->id, 'status' => 'resolved', 'resolution_notes' => 'Sellada'],
+        ]]])->assertOk()->assertJsonPath('results.0.status', 'applied');
+
+        $this->assertEquals('resolved', $issue->fresh()->status);
+        $this->assertNotNull($issue->fresh()->resolved_at);
+    }
+
+    public function test_sync_updates_feature_and_recomputes_phase_progress(): void
+    {
+        $user = User::factory()->create();
+        $user->givePermissionTo('update progress');
+        $project = $this->makeProject($user);
+        $phase = $this->makePhase($project);
+        $feature = $this->makeFeature($this->makeLayer($phase));
+
+        Sanctum::actingAs($user, ['mobile-sync']);
+        $this->postJson('/api/v1/sync', ['operations' => [[
+            'entity' => 'feature', 'op' => 'update', 'uuid' => (string) Str::uuid(),
+            'data' => ['id' => $feature->id, 'status' => 'completed', 'progress' => 100],
+        ]]])->assertOk()->assertJsonPath('results.0.status', 'applied');
+
+        $this->assertEquals(100, $feature->fresh()->progress);
+        $this->assertEquals(100, $phase->fresh()->progress_percent);
+    }
+
+    public function test_sync_returns_conflict_when_server_is_newer(): void
+    {
+        $user = User::factory()->create();
+        $user->givePermissionTo('update progress');
+        $project = $this->makeProject($user);
+
+        Carbon::setTestNow('2026-06-18 12:00:00');
+        $feature = $this->makeFeature($this->makeLayer($this->makePhase($project)));
+        Carbon::setTestNow(); // feature->updated_at = 12:00
+
+        Sanctum::actingAs($user, ['mobile-sync']);
+        // client edited BEFORE the server's last update → conflict
+        $res = $this->postJson('/api/v1/sync', ['operations' => [[
+            'entity' => 'feature', 'op' => 'update', 'uuid' => (string) Str::uuid(),
+            'client_updated_at' => '2026-06-18 11:00:00',
+            'data' => ['id' => $feature->id, 'progress' => 50],
+        ]]])->assertOk();
+
+        $res->assertJsonPath('results.0.status', 'conflict');
+        $this->assertEquals(0, $feature->fresh()->progress); // unchanged
+    }
 }