fix: add domainId to project DTOs and project create UI

apps/api/src/projects/dto/create-project.dto.ts

@@ -8,6 +8,7 @@ import {
   MinLength,
   MaxLength,
   Matches,
+  IsUUID,
 } from "class-validator";
 
 /**
@@ -43,6 +44,10 @@ export class CreateProjectDto {
   })
   color?: string;
 
+  @IsOptional()
+  @IsUUID("4", { message: "domainId must be a valid UUID" })
+  domainId?: string;
+
   @IsOptional()
   @IsObject({ message: "metadata must be an object" })
   metadata?: Record<string, unknown>;

apps/api/src/projects/dto/update-project.dto.ts

@@ -8,6 +8,7 @@ import {
   MinLength,
   MaxLength,
   Matches,
+  IsUUID,
 } from "class-validator";
 
 /**
@@ -45,6 +46,10 @@ export class UpdateProjectDto {
   })
   color?: string | null;
 
+  @IsOptional()
+  @IsUUID("4", { message: "domainId must be a valid UUID" })
+  domainId?: string | null;
+
   @IsOptional()
   @IsObject({ message: "metadata must be an object" })
   metadata?: Record<string, unknown>;

apps/api/src/projects/projects.service.ts

@@ -47,6 +47,9 @@ export class ProjectsService {
     createProjectDto: CreateProjectDto
   ): Promise<ProjectWithRelations> {
     const data: Prisma.ProjectCreateInput = {
+      ...(createProjectDto.domainId
+        ? { domain: { connect: { id: createProjectDto.domainId } } }
+        : {}),
       name: createProjectDto.name,
       description: createProjectDto.description ?? null,
       color: createProjectDto.color ?? null,
@@ -221,6 +224,18 @@ export class ProjectsService {
     if (updateProjectDto.startDate !== undefined) updateData.startDate = updateProjectDto.startDate;
     if (updateProjectDto.endDate !== undefined) updateData.endDate = updateProjectDto.endDate;
     if (updateProjectDto.color !== undefined) updateData.color = updateProjectDto.color;
+    if (updateProjectDto.domainId !== undefined)
+      updateData.domain = updateProjectDto.domainId
+        ? { connect: { id: updateProjectDto.domainId } }
+        : { disconnect: true };
+    if (updateProjectDto.domainId !== undefined)
+      updateData.domain = updateProjectDto.domainId
+        ? {
+            connect: {
+              id: updateProjectDto.domainId,
+            },
+          }
+        : { disconnect: true };
     if (updateProjectDto.metadata !== undefined) {
       updateData.metadata = updateProjectDto.metadata as unknown as Prisma.InputJsonValue;
     }

apps/web/src/app/(authenticated)/projects/page.tsx

@@ -17,6 +17,8 @@ import {
 import { fetchProjects, createProject, deleteProject, ProjectStatus } from "@/lib/api/projects";
 import type { Project, CreateProjectDto } from "@/lib/api/projects";
 import { useWorkspaceId } from "@/lib/hooks";
+import { fetchDomains } from "@/lib/api/domains";
+import type { Domain } from "@mosaic/shared";
 
 /* ---------------------------------------------------------------------------
    Status badge helpers
@@ -65,11 +67,14 @@ interface ProjectCardProps {
   project: Project;
   onDelete: (id: string) => void;
   onClick: (id: string) => void;
+  domains: Domain[];
 }
 
-function ProjectCard({ project, onDelete, onClick }: ProjectCardProps): ReactElement {
+function ProjectCard({ project, onDelete, onClick, domains }: ProjectCardProps): ReactElement {
   const [hovered, setHovered] = useState(false);
   const status = getStatusStyle(project.status);
+  // Find domain if project has a domainId
+  const domain = project.domainId ? domains.find((d) => d.id === project.domainId) : undefined;
 
   return (
     <div
@@ -204,6 +209,22 @@ function ProjectCard({ project, onDelete, onClick }: ProjectCardProps): ReactEle
         >
           {status.label}
         </span>
+        {domain && (
+          <span
+            style={{
+              display: "inline-block",
+              padding: "2px 10px",
+              borderRadius: "var(--r)",
+              background: "rgba(139,92,246,0.15)",
+              color: "var(--purple)",
+              fontSize: "0.75rem",
+              fontWeight: 500,
+              marginLeft: 8,
+            }}
+          >
+            {domain.name}
+          </span>
+        )}
 
         {/* Timestamps */}
         <span
@@ -229,6 +250,7 @@ interface CreateDialogProps {
   onOpenChange: (open: boolean) => void;
   onSubmit: (data: CreateProjectDto) => Promise<void>;
   isSubmitting: boolean;
+  domains: Domain[];
 }
 
 function CreateProjectDialog({
@@ -236,20 +258,24 @@ function CreateProjectDialog({
   onOpenChange,
   onSubmit,
   isSubmitting,
+  domains,
 }: CreateDialogProps): ReactElement {
   const [name, setName] = useState("");
   const [description, setDescription] = useState("");
   const [formError, setFormError] = useState<string | null>(null);
+  const [domainId, setDomainId] = useState("");
 
   function resetForm(): void {
     setName("");
     setDescription("");
     setFormError(null);
+    setDomainId("");
   }
 
   async function handleSubmit(e: SyntheticEvent): Promise<void> {
     e.preventDefault();
     setFormError(null);
+    setDomainId("");
 
     const trimmedName = name.trim();
     if (!trimmedName) {
@@ -263,6 +289,9 @@ function CreateProjectDialog({
       if (trimmedDesc) {
         payload.description = trimmedDesc;
       }
+      if (domainId) {
+        payload.domainId = domainId;
+      }
       await onSubmit(payload);
       resetForm();
     } catch (err: unknown) {
@@ -382,6 +411,47 @@ function CreateProjectDialog({
               />
             </div>
 
+            {/* Domain */}
+            <div style={{ marginBottom: 16 }}>
+              <label
+                htmlFor="project-domain"
+                style={{
+                  display: "block",
+                  marginBottom: 6,
+                  fontSize: "0.85rem",
+                  fontWeight: 500,
+                  color: "var(--text-2)",
+                }}
+              >
+                Domain (optional)
+              </label>
+              <select
+                id="project-domain"
+                value={domainId}
+                onChange={(e) => {
+                  setDomainId(e.target.value);
+                }}
+                style={{
+                  width: "100%",
+                  padding: "8px 12px",
+                  background: "var(--bg)",
+                  border: "1px solid var(--border)",
+                  borderRadius: "var(--r)",
+                  color: "var(--text)",
+                  fontSize: "0.9rem",
+                  outline: "none",
+                  boxSizing: "border-box",
+                }}
+              >
+                <option value="">None</option>
+                {domains.map((d) => (
+                  <option key={d.id} value={d.id}>
+                    {d.name}
+                  </option>
+                ))}
+              </select>
+            </div>
+
             {/* Form error */}
             {formError !== null && (
               <p style={{ color: "var(--danger)", fontSize: "0.85rem", margin: "0 0 12px" }}>
@@ -532,6 +602,7 @@ export default function ProjectsPage(): ReactElement {
   const workspaceId = useWorkspaceId();
 
   const [projects, setProjects] = useState<Project[]>([]);
+  const [domains, setDomains] = useState<Domain[]>([]);
   const [isLoading, setIsLoading] = useState(true);
   const [error, setError] = useState<string | null>(null);
 
@@ -601,6 +672,33 @@ export default function ProjectsPage(): ReactElement {
     };
   }, [workspaceId]);
 
+  // Load domains
+  useEffect(() => {
+    if (!workspaceId) {
+      return;
+    }
+
+    let cancelled = false;
+    const wsId = workspaceId;
+
+    async function loadDomains(): Promise<void> {
+      try {
+        const response = await fetchDomains(undefined, wsId);
+        if (!cancelled) {
+          setDomains(response.data);
+        }
+      } catch (err: unknown) {
+        console.error("[Projects] Failed to fetch domains:", err);
+      }
+    }
+
+    void loadDomains();
+
+    return (): void => {
+      cancelled = true;
+    };
+  }, [workspaceId]);
+
   function handleRetry(): void {
     void loadProjects(workspaceId);
   }
@@ -779,6 +877,7 @@ export default function ProjectsPage(): ReactElement {
               project={project}
               onDelete={handleDeleteRequest}
               onClick={handleCardClick}
+              domains={domains}
             />
           ))}
         </div>
@@ -790,6 +889,7 @@ export default function ProjectsPage(): ReactElement {
         onOpenChange={setCreateOpen}
         onSubmit={handleCreate}
         isSubmitting={isCreating}
+        domains={domains}
       />
 
       {/* Delete Confirmation Dialog */}

apps/web/src/lib/api/projects.ts

@@ -95,6 +95,7 @@ export interface CreateProjectDto {
   startDate?: string;
   endDate?: string;
   color?: string;
+  domainId?: string;
   metadata?: Record<string, unknown>;
 }
 
@@ -108,6 +109,7 @@ export interface UpdateProjectDto {
   startDate?: string | null;
   endDate?: string | null;
   color?: string | null;
+  domainId?: string | null;
   metadata?: Record<string, unknown>;
 }