diff --git a/app/Actions/Draft/FindOrCreateDraftStudy.php b/app/Actions/Draft/FindOrCreateDraftStudy.php
index 71fb7059..e52fd577 100644
--- a/app/Actions/Draft/FindOrCreateDraftStudy.php
+++ b/app/Actions/Draft/FindOrCreateDraftStudy.php
@@ -25,6 +25,8 @@ public function execute(FileSystemObject $folder, Draft $draft, Project $project
         if (! $study) {
             $study = $this->createNewStudy($folder, $draft, $project, $validation);
             $this->updateFolderWithStudy($folder, $study);
+        } else {
+            $this->reassignStudyToProject($study, $project);
         }
 
         return $study;
@@ -66,4 +68,20 @@ private function updateFolderWithStudy(FileSystemObject $folder, Study $study):
         $folder->study_id = $study->id;
         $folder->save();
     }
+
+    /**
+     * Keep an existing study on the project this process run is using.
+     */
+    private function reassignStudyToProject(Study $study, Project $project): void
+    {
+        if ($study->project_id === $project->id) {
+            return;
+        }
+
+        $study->project_id = $project->id;
+        $study->save();
+
+        $study->sample()->update(['project_id' => $project->id]);
+        $study->datasets()->update(['project_id' => $project->id]);
+    }
 }
diff --git a/app/Actions/Draft/ProcessDraft.php b/app/Actions/Draft/ProcessDraft.php
index 79fc4bf9..8aacb639 100644
--- a/app/Actions/Draft/ProcessDraft.php
+++ b/app/Actions/Draft/ProcessDraft.php
@@ -15,7 +15,6 @@
 use App\Models\Validation;
 use App\Support\Draft\HifsaPdfResolver;
 use Illuminate\Http\JsonResponse;
-use Illuminate\Http\RedirectResponse;
 use Illuminate\Http\Request;
 use Illuminate\Http\Response;
 use Illuminate\Support\Facades\DB;
@@ -36,7 +35,7 @@ public function __construct(
     /**
      * Process draft and create project structure.
      */
-    public function execute(Request $request, Draft $draft, User $user): Response|JsonResponse|RedirectResponse
+    public function execute(Request $request, Draft $draft, User $user): Response|JsonResponse
     {
         [$user_id, $team_id, $team] = $user->getUserTeamData();
 
@@ -94,7 +93,7 @@ private function prepareDraft(Request $request, Draft $draft): void
      */
     public function createOrUpdateProject(Draft $draft, int $user_id, int $team_id, $user, $team): Project
     {
-        $project = Project::where('draft_id', $draft->id)->first();
+        $project = $this->resolveDraftProject($draft);
 
         if (! $project) {
             $project = $this->createNewProject($draft, $user_id, $team_id, $user, $team);
@@ -105,6 +104,40 @@ public function createOrUpdateProject(Draft $draft, int $user_id, int $team_id,
         return $project;
     }
 
+    /**
+     * Pick the existing project for this draft.
+     *
+     * A draft can accumulate more than one project row (retries, concurrent
+     * process requests). `first()` without an order then often returns an
+     * empty newer project while studies still belong to an older one, so
+     * finalizeProcessing sees zero studies and redirects.
+     */
+    public function resolveDraftProject(Draft $draft): ?Project
+    {
+        $studyProjectId = Study::query()
+            ->where('draft_id', $draft->id)
+            ->whereNotNull('project_id')
+            ->value('project_id');
+
+        if ($studyProjectId) {
+            $project = Project::query()->find($studyProjectId);
+
+            if ($project) {
+                if ($project->draft_id !== $draft->id) {
+                    $project->draft_id = $draft->id;
+                    $project->save();
+                }
+
+                return $project;
+            }
+        }
+
+        return Project::query()
+            ->where('draft_id', $draft->id)
+            ->orderBy('id')
+            ->first();
+    }
+
     /**
      * Create a new project from draft.
      */
@@ -363,7 +396,7 @@ public function createDatasetFromOrphanedFile(FileSystemObject $folder, Study $s
     /**
      * Finalize processing and return response.
      */
-    public function finalizeProcessing(Draft $draft, Project $project): Response|JsonResponse|RedirectResponse
+    public function finalizeProcessing(Draft $draft, Project $project): Response|JsonResponse
     {
         $draft->save();
 
@@ -371,8 +404,15 @@ public function finalizeProcessing(Draft $draft, Project $project): Response|Jso
         $this->hifsaPdfResolver->persistCsvData($studies);
         $studies = $this->hifsaPdfResolver->enrichStudies($studies, $draft);
 
-        if (count($studies) == 0) {
-            return redirect()->back()->withErrors(['studies' => 'nmrXiv requires raw or processed raw instrument output files. If you data is from a single sample organise all the files in one folder and click proceed. If you have multiple samples, group your data in subfolders with each subfolder corresponding to a sample. Thank you.']);
+        if ($studies->isEmpty()) {
+            $message = 'nmrXiv requires raw or processed raw instrument output files. If you data is from a single sample organise all the files in one folder and click proceed. If you have multiple samples, group your data in subfolders with each subfolder corresponding to a sample. Thank you.';
+
+            return response()->json([
+                'message' => $message,
+                'errors' => [
+                    'studies' => [$message],
+                ],
+            ], 422);
         }
 
         Log::info('Finalizing processing for draft '.$draft->id);
diff --git a/app/Actions/Project/PublishEmbargoProject.php b/app/Actions/Project/PublishEmbargoProject.php
index 07868045..89336b56 100644
--- a/app/Actions/Project/PublishEmbargoProject.php
+++ b/app/Actions/Project/PublishEmbargoProject.php
@@ -103,7 +103,7 @@ private function validateForPublication(Project $project, bool $restoreReleaseDa
         $project->release_date = now()->startOfDay()->toDateString();
         $project->save();
 
-        $validation->process();
+        $validation->process(project: $project);
         $publishAttemptValidation = $validation->fresh();
 
         if (! $publishAttemptValidation['report']['project']['status']) {
@@ -113,7 +113,7 @@ private function validateForPublication(Project $project, bool $restoreReleaseDa
                 $project->refresh();
 
                 if ($project->validation) {
-                    $project->validation->process();
+                    $project->validation->process(project: $project);
                 }
             }
 
diff --git a/app/Actions/Project/UpdateProject.php b/app/Actions/Project/UpdateProject.php
index fa1fd6be..c886584c 100644
--- a/app/Actions/Project/UpdateProject.php
+++ b/app/Actions/Project/UpdateProject.php
@@ -149,7 +149,7 @@ public function update(Project $project, array $input)
                     }
                 }
             }
-            $validation->process();
+            $validation->process(project: $project);
 
             $project = $project->fresh();
 
diff --git a/app/Http/Controllers/DraftController.php b/app/Http/Controllers/DraftController.php
index 8757bb28..8b71f921 100644
--- a/app/Http/Controllers/DraftController.php
+++ b/app/Http/Controllers/DraftController.php
@@ -16,7 +16,6 @@
 use App\Support\ProvisionalDoi;
 use Illuminate\Database\Eloquent\Collection;
 use Illuminate\Http\JsonResponse;
-use Illuminate\Http\RedirectResponse;
 use Illuminate\Http\Request;
 use Illuminate\Http\Response;
 use Illuminate\Support\Facades\Auth;
@@ -67,10 +66,8 @@ public function all(Request $request): JsonResponse
 
     /**
      * Process draft and convert to project structure.
-     *
-     * @return Response|JsonResponse|RedirectResponse
      */
-    public function process(Request $request, Draft $draft)
+    public function process(Request $request, Draft $draft): Response|JsonResponse
     {
         $this->authorize('updateDraft', $draft);
 
@@ -176,7 +173,7 @@ public function complete(Request $request, Draft $draft): JsonResponse
     {
         $this->authorize('updateDraft', $draft);
 
-        $project = Project::where('draft_id', $draft->id)->first();
+        $project = $this->processDraft->resolveDraftProject($draft);
 
         if (! $project) {
             return response()->json([
@@ -186,10 +183,12 @@ public function complete(Request $request, Draft $draft): JsonResponse
         }
 
         $validation = $project->validation;
-        $validation->process();
+        $validation->process(project: $project);
+
+        $project->load(['studies.datasets', 'owner', 'citations', 'authors', 'tags']);
 
         return response()->json([
-            'project' => Project::with(['studies.datasets', 'owner', 'citations', 'authors', 'tags'])->where('draft_id', $draft->id)->first(),
+            'project' => $project,
             'validation' => $validation,
         ]);
     }
@@ -201,7 +200,7 @@ public function info(Request $request, Draft $draft): JsonResponse
     {
         $this->authorize('updateDraft', $draft);
 
-        $project = Project::where('draft_id', $draft->id)->first();
+        $project = $this->processDraft->resolveDraftProject($draft);
 
         if (! $project) {
             return response()->json([
@@ -268,7 +267,7 @@ public function status(Request $request, Draft $draft): JsonResponse
     {
         $this->authorize('updateDraft', $draft);
 
-        $project = Project::where('draft_id', $draft->id)->first();
+        $project = $this->processDraft->resolveDraftProject($draft);
 
         if (! $project) {
             return response()->json([
@@ -321,7 +320,7 @@ public function storeProvisionalDoi(Request $request, Draft $draft): JsonRespons
             $payload = DB::transaction(function () use ($draft, $user, $user_id, $team_id, $team): array {
                 Draft::query()->whereKey($draft->id)->lockForUpdate()->firstOrFail();
 
-                $project = Project::query()->where('draft_id', $draft->id)->first();
+                $project = $this->processDraft->resolveDraftProject($draft);
 
                 if (! $project) {
                     $project = $this->processDraft->createNewProject($draft, $user_id, $team_id, $user, $team);
@@ -357,7 +356,7 @@ public function destroyProvisionalDoi(Request $request, Draft $draft): Response
     {
         $this->authorize('updateDraft', $draft);
 
-        $project = Project::query()->where('draft_id', $draft->id)->first();
+        $project = $this->processDraft->resolveDraftProject($draft);
 
         if (! $project) {
             return response()->noContent();
diff --git a/app/Http/Controllers/ProjectController.php b/app/Http/Controllers/ProjectController.php
index 0a6b7822..92eac14a 100644
--- a/app/Http/Controllers/ProjectController.php
+++ b/app/Http/Controllers/ProjectController.php
@@ -349,7 +349,7 @@ public function validation(Request $request, Project $project)
             }
         }
 
-        $validation->process();
+        $validation->process(project: $project);
 
         return Inertia::render('Project/Validation', [
             'project' => $project->load('projectInvitations', 'tags', 'authors', 'citations', 'fundingReferences'),
@@ -377,7 +377,7 @@ public function validationReport(Request $request, Project $project)
             }
         }
 
-        $validation->process();
+        $validation->process(project: $project);
 
         return $validation->fresh();
     }
@@ -409,7 +409,7 @@ public function publish(Request $request, Project $project, PublishProject $publ
                 }
 
                 $project->release_date = $request->get('release_date');
-                $validation->process();
+                $validation->process(project: $project);
                 $validation = $validation->fresh();
                 if ($validation['report']['project']['status']) {
                     $project->status = 'queued';
@@ -467,7 +467,7 @@ public function publish(Request $request, Project $project, PublishProject $publ
 
                 $validation = $project->validation;
                 if ($validation) {
-                    $validation->process(forceSamplesMode: true);
+                    $validation->process(forceSamplesMode: true, project: $project);
                     $validation = $validation->fresh();
                 }
 
@@ -562,7 +562,7 @@ protected function publishValidationHintsFromReport(?array $report): array
 
         $citations = $project['citations'] ?? null;
         if (is_string($citations) && str_starts_with($citations, 'false|')) {
-            $hints[] = 'Add a DOI to every citation, or choose a future release date if you are not ready to publish immediately.';
+            $hints[] = 'Add at least one citation before publishing in project mode.';
         }
 
         $labels = [
diff --git a/app/Http/Controllers/UploadController.php b/app/Http/Controllers/UploadController.php
index 09286c2f..ac703908 100644
--- a/app/Http/Controllers/UploadController.php
+++ b/app/Http/Controllers/UploadController.php
@@ -2,8 +2,8 @@
 
 namespace App\Http\Controllers;
 
+use App\Actions\Draft\ProcessDraft;
 use App\Models\Draft;
-use App\Models\Project;
 use Illuminate\Auth\Access\AuthorizationException;
 use Illuminate\Http\Request;
 use Illuminate\Support\Facades\Auth;
@@ -12,6 +12,8 @@
 
 class UploadController extends Controller
 {
+    public function __construct(private ProcessDraft $processDraft) {}
+
     public function upload(Request $request)
     {
         $draftId = $request->get('draft_id');
@@ -20,7 +22,7 @@ public function upload(Request $request)
             $draft = Draft::find((int) $draftId);
 
             if ($draft && $request->user()?->can('updateDraft', $draft)) {
-                $project = Project::where('draft_id', $draft->id)->first();
+                $project = $this->processDraft->resolveDraftProject($draft);
 
                 if ($project && $project->status !== 'draft') {
                     return redirect()->route('publish', ['draft' => $draft->id]);
@@ -39,7 +41,7 @@ public function publish(Request $request, Draft $draft)
     {
         $this->authorize('updateDraft', $draft);
 
-        $project = Project::where('draft_id', $draft->id)->first();
+        $project = $this->processDraft->resolveDraftProject($draft);
 
         if (! $project) {
             return redirect()->route('upload', ['draft_id' => $draft->id]);
@@ -50,11 +52,23 @@ public function publish(Request $request, Draft $draft)
         }
 
         $validation = $project->validation;
-        $validation->process();
+        $validation->process(project: $project);
+
+        $project->load([
+            'studies.datasets',
+            'studies.sample.molecules',
+            'studies.sample.mixtureComposition.components.molecule',
+            'owner',
+            'citations',
+            'fundingReferences',
+            'authors',
+            'tags',
+            'license',
+        ]);
 
         return Inertia::render('Publish', [
             'draft' => $draft,
-            'project' => Project::with(['studies.datasets', 'studies.sample.molecules', 'studies.sample.mixtureComposition.components.molecule', 'owner', 'citations', 'fundingReferences', 'authors', 'tags', 'license'])->where('draft_id', $draft->id)->first(),
+            'project' => $project,
             'validation' => $validation,
         ]);
     }
diff --git a/app/Jobs/ProcessFiles.php b/app/Jobs/ProcessFiles.php
index a43ca437..c5b5d745 100644
--- a/app/Jobs/ProcessFiles.php
+++ b/app/Jobs/ProcessFiles.php
@@ -2,9 +2,9 @@
 
 namespace App\Jobs;
 
+use App\Actions\Draft\ProcessDraft;
 use App\Models\Draft;
 use App\Models\FileSystemObject;
-use App\Models\Project;
 use Illuminate\Bus\Queueable;
 use Illuminate\Contracts\Queue\ShouldBeUnique;
 use Illuminate\Contracts\Queue\ShouldQueue;
@@ -119,7 +119,7 @@ private function updateFileSystemObjectStatus(FileSystemObject $fsObject): bool
      */
     private function handleMissingFilesRestored(): void
     {
-        $project = Project::where('draft_id', $this->draft->id)->first();
+        $project = app(ProcessDraft::class)->resolveDraftProject($this->draft);
 
         if (! $project) {
             Log::warning('No project found for draft '.$this->draft->id);
diff --git a/app/Jobs/ValidateAndSubmitELNDraft.php b/app/Jobs/ValidateAndSubmitELNDraft.php
index a15c2c5e..4ee566b3 100644
--- a/app/Jobs/ValidateAndSubmitELNDraft.php
+++ b/app/Jobs/ValidateAndSubmitELNDraft.php
@@ -76,7 +76,7 @@ public function handle(): void
 
             // Process validation
             $validation = $project->validation;
-            $validation->process();
+            $validation->process(project: $project);
             $validation = $validation->fresh();
 
             $status = true;
diff --git a/app/Models/Validation.php b/app/Models/Validation.php
index 3ab56f48..ef965b38 100644
--- a/app/Models/Validation.php
+++ b/app/Models/Validation.php
@@ -82,9 +82,28 @@ public function project(): HasOne
         return $this->hasOne(Project::class);
     }
 
-    public function process(bool $forceSamplesMode = false): void
+    public function projects(): HasMany
     {
-        if (! $project = $this->project) {
+        return $this->hasMany(Project::class);
+    }
+
+    /**
+     * Project this validation should score when several project rows share validation_id.
+     */
+    public function associatedProject(): ?Project
+    {
+        return $this->projects()
+            ->withCount('studies')
+            ->orderByDesc('studies_count')
+            ->orderBy('id')
+            ->first();
+    }
+
+    public function process(bool $forceSamplesMode = false, ?Project $project = null): void
+    {
+        $project ??= $this->associatedProject();
+
+        if (! $project) {
             return;
         }
 
@@ -151,14 +170,16 @@ public function process(bool $forceSamplesMode = false): void
                 'id' => $study->id,
             ];
 
+            $moleculeIds = $study->sample?->molecules?->pluck('id')->toArray() ?? [];
+
             $values = [
                 'title' => $study->name,
                 'description' => $study->description,
                 'keywords' => $study->tags->pluck('id')->toArray(),
-                'composition' => $study->sample->molecules->pluck('id')->toArray(),
+                'composition' => $moleculeIds,
                 'nmrium_info' => $study->has_nmrium ? $study->has_nmrium : null,
                 'sample' => $study->sample,
-                'molecules' => $study->sample->molecules->pluck('id')->toArray(),
+                'molecules' => $moleculeIds,
             ];
 
             $study_rules = $rules['study'];
@@ -256,14 +277,14 @@ public function process(bool $forceSamplesMode = false): void
             array_push($studiesValidation, $studyReport);
         }
 
-        // Validate citations
+        // Validate citations. The associated article DOI is optional.
         $citations = $project->citations;
         $citationsValidation = [];
         $citationsStatus = $citations && $citations->isNotEmpty();
-        $shouldValidateCitationDoi = ! $samplesMode;
+        $shouldAnnotateCitationDoi = ! $samplesMode;
 
-        if ($shouldValidateCitationDoi && $project->release_date) {
-            $shouldValidateCitationDoi = Carbon::parse($project->release_date)->lessThanOrEqualTo(now());
+        if ($shouldAnnotateCitationDoi && $project->release_date) {
+            $shouldAnnotateCitationDoi = Carbon::parse($project->release_date)->lessThanOrEqualTo(now());
         }
 
         if ($citations && $citations->isNotEmpty()) {
@@ -273,18 +294,9 @@ public function process(bool $forceSamplesMode = false): void
                     'id' => $citation->id,
                 ];
 
-                if ($shouldValidateCitationDoi) {
-                    // Check if DOI is present only for current/past release date projects.
-                    $hasDoi = is_string($citation->doi) && trim($citation->doi) !== '';
-
-                    if ($hasDoi) {
-                        $citationReport['doi'] = 'true|required';
-                    } else {
-                        $citationReport['doi'] = 'false|required';
-                        $citationsStatus = false; // Citation validation failed
-                    }
-
-                    $citationReport['status'] = $hasDoi;
+                if ($shouldAnnotateCitationDoi) {
+                    $citationReport['doi'] = 'true|optional';
+                    $citationReport['status'] = true;
                 } else {
                     $citationReport['doi'] = $samplesMode
                         ? 'true|skipped-samples-mode'
diff --git a/tests/Feature/Draft/ProcessDraftProjectReuseTest.php b/tests/Feature/Draft/ProcessDraftProjectReuseTest.php
new file mode 100644
index 00000000..ccc02ff2
--- /dev/null
+++ b/tests/Feature/Draft/ProcessDraftProjectReuseTest.php
@@ -0,0 +1,146 @@
+<?php
+
+namespace Tests\Feature\Draft;
+
+use App\Actions\Draft\ProcessDraft;
+use App\Jobs\ArchiveStudy;
+use App\Models\Draft;
+use App\Models\FileSystemObject;
+use App\Models\Project;
+use App\Models\Sample;
+use App\Models\Study;
+use App\Models\Team;
+use App\Models\User;
+use App\Models\Validation;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Illuminate\Support\Facades\Bus;
+use Tests\TestCase;
+
+class ProcessDraftProjectReuseTest extends TestCase
+{
+    use RefreshDatabase;
+
+    private User $user;
+
+    private Team $team;
+
+    private Draft $draft;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $this->user = User::factory()->withPersonalTeam()->create();
+        $this->team = $this->user->currentTeam;
+        $this->draft = Draft::factory()->create([
+            'name' => 'Reuse Draft Project',
+            'owner_id' => $this->user->id,
+            'team_id' => $this->team->id,
+        ]);
+    }
+
+    public function test_resolve_draft_project_prefers_the_project_that_already_has_studies(): void
+    {
+        $emptyProject = $this->makeProject('Empty sibling project');
+        $studyProject = $this->makeProject('Project with studies');
+
+        $folder = $this->makeStudyFolder('sample-a');
+        $this->makeStudy($studyProject, $folder, 'sample-a');
+
+        $resolved = app(ProcessDraft::class)->resolveDraftProject($this->draft);
+
+        $this->assertNotNull($resolved);
+        $this->assertSame($studyProject->id, $resolved->id);
+        $this->assertNotSame($emptyProject->id, $resolved->id);
+    }
+
+    public function test_process_returns_existing_studies_when_another_empty_project_shares_the_draft(): void
+    {
+        Bus::fake();
+
+        $this->makeProject('Empty sibling project');
+        $studyProject = $this->makeProject('Project with studies');
+
+        $folder = $this->makeStudyFolder('sample-a');
+        $this->makeStudy($studyProject, $folder, 'sample-a');
+
+        $response = $this->actingAs($this->user)
+            ->postJson('/dashboard/drafts/'.$this->draft->id.'/process', [
+                'name' => $this->draft->name,
+            ]);
+
+        $response->assertOk()
+            ->assertJsonPath('project.id', $studyProject->id)
+            ->assertJsonCount(1, 'studies');
+
+        Bus::assertDispatched(ArchiveStudy::class);
+    }
+
+    public function test_process_returns_json_validation_error_instead_of_redirect_when_no_studies(): void
+    {
+        FileSystemObject::factory()->file()->rootLevel()->create([
+            'name' => 'notes.txt',
+            'draft_id' => $this->draft->id,
+            'status' => 'present',
+        ]);
+
+        $response = $this->actingAs($this->user)
+            ->postJson('/dashboard/drafts/'.$this->draft->id.'/process', [
+                'name' => $this->draft->name,
+            ]);
+
+        $response->assertStatus(422)
+            ->assertJsonValidationErrors(['studies']);
+    }
+
+    private function makeProject(string $name): Project
+    {
+        $validation = Validation::factory()->create();
+
+        return Project::factory()->create([
+            'name' => $name,
+            'owner_id' => $this->user->id,
+            'team_id' => $this->team->id,
+            'draft_id' => $this->draft->id,
+            'license_id' => null,
+            'validation_id' => $validation->id,
+        ]);
+    }
+
+    private function makeStudyFolder(string $name): FileSystemObject
+    {
+        return FileSystemObject::factory()->directory()->rootLevel()->create([
+            'name' => $name,
+            'draft_id' => $this->draft->id,
+            'model_type' => 'study',
+            'status' => 'present',
+            'has_children' => true,
+        ]);
+    }
+
+    private function makeStudy(Project $project, FileSystemObject $folder, string $name): Study
+    {
+        $study = Study::factory()->create([
+            'name' => $name,
+            'project_id' => $project->id,
+            'team_id' => $this->team->id,
+            'owner_id' => $this->user->id,
+            'draft_id' => $this->draft->id,
+            'fs_id' => $folder->id,
+            'license_id' => null,
+        ]);
+
+        $folder->update([
+            'study_id' => $study->id,
+            'project_id' => $project->id,
+        ]);
+
+        Sample::factory()->create([
+            'name' => $name.'_sample',
+            'study_id' => $study->id,
+            'project_id' => $project->id,
+        ]);
+
+        return $study;
+    }
+}
diff --git a/tests/Feature/Project/ProjectValidationTest.php b/tests/Feature/Project/ProjectValidationTest.php
index 2f9aa820..de4ae030 100644
--- a/tests/Feature/Project/ProjectValidationTest.php
+++ b/tests/Feature/Project/ProjectValidationTest.php
@@ -200,4 +200,36 @@ public function test_validation_processes_empty_project()
         $this->assertNotNull($validation->report);
         $this->assertIsArray($validation->report);
     }
+
+    public function test_validation_report_includes_studies_when_an_empty_sibling_shares_validation(): void
+    {
+        $validation = Validation::factory()->create();
+        $this->project->validation()->associate($validation);
+        $this->project->save();
+
+        Project::factory()->create([
+            'validation_id' => $validation->id,
+            'name' => 'Empty sibling',
+            'owner_id' => $this->user->id,
+            'team_id' => $this->user->personalTeam()->id,
+        ]);
+
+        $study = Study::factory()->for($this->project)->create([
+            'name' => 'NMR sample',
+            'owner_id' => $this->user->id,
+            'validation_id' => $validation->id,
+        ]);
+
+        Sample::factory()->create([
+            'study_id' => $study->id,
+            'project_id' => $this->project->id,
+        ]);
+
+        $response = $this->actingAs($this->user)
+            ->get(route('project.validation', $this->project));
+
+        $response->assertStatus(200)
+            ->assertJsonPath('report.project.studies.0.id', $study->id)
+            ->assertJsonPath('report.project.studies.0.name', 'NMR sample');
+    }
 }
diff --git a/tests/Feature/Project/PublishEmbargoProjectValidationTest.php b/tests/Feature/Project/PublishEmbargoProjectValidationTest.php
index fbe0c032..e7737bcb 100644
--- a/tests/Feature/Project/PublishEmbargoProjectValidationTest.php
+++ b/tests/Feature/Project/PublishEmbargoProjectValidationTest.php
@@ -56,7 +56,7 @@ public function test_failed_publish_now_restores_validation_report_for_original_
         $response->assertStatus(422);
         $response->assertJsonPath(
             'validation.report.project.citations_detail.0.doi',
-            'false|required'
+            'true|optional'
         );
 
         $project->refresh();
diff --git a/tests/Feature/Project/PublishProjectTest.php b/tests/Feature/Project/PublishProjectTest.php
index 0e0a54dc..3356ce79 100644
--- a/tests/Feature/Project/PublishProjectTest.php
+++ b/tests/Feature/Project/PublishProjectTest.php
@@ -126,7 +126,7 @@ public function test_project_publication_updates_validation_status()
     }
 
     #[Test]
-    public function citations_without_doi_fail_validation(): void
+    public function citations_without_doi_pass_validation(): void
     {
         $this->project->draft->update(['project_enabled' => true]);
 
@@ -144,12 +144,10 @@ public function citations_without_doi_fail_validation(): void
 
         $validation->process();
 
-        // Check that validation report shows citation without DOI
-        $this->assertFalse($validation->report['project']['status']);
-        $this->assertEquals('false|required', $validation->report['project']['citations']);
+        $this->assertEquals('true|required', $validation->report['project']['citations']);
         $this->assertNotEmpty($validation->report['project']['citations_detail']);
-        $this->assertEquals(false, $validation->report['project']['citations_detail'][0]['status']);
-        $this->assertEquals('false|required', $validation->report['project']['citations_detail'][0]['doi']);
+        $this->assertEquals(true, $validation->report['project']['citations_detail'][0]['status']);
+        $this->assertEquals('true|optional', $validation->report['project']['citations_detail'][0]['doi']);
     }
 
     #[Test]
@@ -175,7 +173,7 @@ public function citations_with_doi_pass_validation(): void
         $this->assertEquals('true|required', $validation->report['project']['citations']);
         $this->assertNotEmpty($validation->report['project']['citations_detail']);
         $this->assertEquals(true, $validation->report['project']['citations_detail'][0]['status']);
-        $this->assertEquals('true|required', $validation->report['project']['citations_detail'][0]['doi']);
+        $this->assertEquals('true|optional', $validation->report['project']['citations_detail'][0]['doi']);
     }
 
     #[Test]
diff --git a/tests/Feature/UploadTest.php b/tests/Feature/UploadTest.php
index 92ee00c5..2a41f17b 100644
--- a/tests/Feature/UploadTest.php
+++ b/tests/Feature/UploadTest.php
@@ -5,6 +5,8 @@
 use App\Models\Draft;
 use App\Models\FileSystemObject;
 use App\Models\Project;
+use App\Models\Sample;
+use App\Models\Study;
 use App\Models\User;
 use App\Models\Validation;
 use Illuminate\Foundation\Testing\RefreshDatabase;
@@ -227,6 +229,53 @@ public function test_publish_renders_for_authorized_user(): void
         $response->assertStatus(200);
     }
 
+    public function test_publish_uses_the_draft_project_that_has_studies_not_a_later_empty_sibling(): void
+    {
+        $validation = Validation::factory()->create();
+        $draft = Draft::factory()->create([
+            'owner_id' => $this->user->id,
+            'team_id' => $this->user->currentTeam->id,
+        ]);
+
+        $ownedProject = Project::factory()->create([
+            'draft_id' => $draft->id,
+            'owner_id' => $this->user->id,
+            'team_id' => $this->user->currentTeam->id,
+            'validation_id' => $validation->id,
+            'license_id' => null,
+        ]);
+
+        $study = Study::factory()->create([
+            'name' => 'sample-a',
+            'project_id' => $ownedProject->id,
+            'team_id' => $this->user->currentTeam->id,
+            'owner_id' => $this->user->id,
+            'draft_id' => $draft->id,
+            'license_id' => null,
+        ]);
+        Sample::factory()->create([
+            'name' => 'sample-a_sample',
+            'study_id' => $study->id,
+            'project_id' => $ownedProject->id,
+        ]);
+
+        $otherUser = User::factory()->withPersonalTeam()->create();
+        Project::factory()->create([
+            'draft_id' => $draft->id,
+            'owner_id' => $otherUser->id,
+            'team_id' => $otherUser->currentTeam->id,
+            'license_id' => null,
+        ]);
+
+        $response = $this->actingAs($this->user)
+            ->get('/publish/'.$draft->id);
+
+        $response->assertStatus(200);
+
+        $page = $this->inertiaPageFromResponse($response);
+        $this->assertSame($ownedProject->id, $page['props']['project']['id']);
+    }
+
     public function test_publish_processes_project_validation(): void
     {
         $validation = Validation::factory()->create();
diff --git a/tests/Unit/Models/ValidationModelTest.php b/tests/Unit/Models/ValidationModelTest.php
index 18e372ef..bb976f25 100644
--- a/tests/Unit/Models/ValidationModelTest.php
+++ b/tests/Unit/Models/ValidationModelTest.php
@@ -417,6 +417,45 @@ public function test_process_method_validates_project_fields()
         $this->assertArrayHasKey('project', $validation->report);
     }
 
+    public function test_process_scores_studies_when_an_earlier_empty_project_shares_validation(): void
+    {
+        $validation = new Validation;
+        $validation->save();
+
+        Project::factory()->create([
+            'validation_id' => $validation->id,
+            'name' => 'Empty sibling',
+        ]);
+
+        $project = Project::factory()->create([
+            'validation_id' => $validation->id,
+            'name' => 'Project with studies',
+        ]);
+
+        $study = Study::factory()->create([
+            'validation_id' => $validation->id,
+            'project_id' => $project->id,
+            'name' => 'Sample A',
+        ]);
+
+        Sample::factory()->create([
+            'study_id' => $study->id,
+            'project_id' => $project->id,
+        ]);
+
+        config(['validations.default' => 'v1']);
+        config(['validations.v1.project' => []]);
+        config(['validations.v1.study' => []]);
+        config(['validations.v1.dataset' => []]);
+
+        $validation->process();
+        $validation->refresh();
+
+        $this->assertCount(1, $validation->report['project']['studies']);
+        $this->assertSame($study->id, $validation->report['project']['studies'][0]['id']);
+        $this->assertSame('Sample A', $validation->report['project']['studies'][0]['name']);
+    }
+
     public function test_process_method_handles_project_with_studies()
     {
         $validation = new Validation;