diff --git a/packages/api/src/__tests__/client-procedure-support.test.ts b/packages/api/src/__tests__/client-procedure-support.test.ts
new file mode 100644
index 0000000..88ef54e
--- /dev/null
+++ b/packages/api/src/__tests__/client-procedure-support.test.ts
@@ -0,0 +1,318 @@
+import { TRPCError } from "@trpc/server";
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+const { createAuditEntry } = vi.hoisted(() => ({
+  createAuditEntry: vi.fn(),
+}));
+
+vi.mock("../lib/audit.js", () => ({
+  createAuditEntry,
+}));
+
+import {
+  batchUpdateClientSortOrder,
+  createClient,
+  deleteClient,
+  updateClient,
+} from "../router/client-procedure-support.js";
+
+function createContext(db: Record<string, unknown>) {
+  return {
+    db: db as never,
+    dbUser: { id: "user_1" } as never,
+  };
+}
+
+describe("client procedure support", () => {
+  beforeEach(() => {
+    createAuditEntry.mockReset();
+  });
+
+  it("creates a client after validating parent and code uniqueness", async () => {
+    const findUnique = vi
+      .fn()
+      .mockResolvedValueOnce({ id: "parent_1", name: "Parent" })
+      .mockResolvedValueOnce(null);
+    const create = vi.fn().mockResolvedValue({
+      id: "client_1",
+      name: "Acme",
+      code: "ACME",
+      parentId: "parent_1",
+      sortOrder: 12,
+      tags: ["enterprise"],
+      isActive: true,
+    });
+
+    const result = await createClient(
+      createContext({
+        client: {
+          findUnique,
+          create,
+        },
+      }),
+      {
+        name: "Acme",
+        code: "ACME",
+        parentId: "parent_1",
+        sortOrder: 12,
+        tags: ["enterprise"],
+      },
+    );
+
+    expect(findUnique).toHaveBeenNthCalledWith(1, {
+      where: { id: "parent_1" },
+    });
+    expect(findUnique).toHaveBeenNthCalledWith(2, {
+      where: { code: "ACME" },
+    });
+    expect(create).toHaveBeenCalledWith({
+      data: {
+        name: "Acme",
+        code: "ACME",
+        parentId: "parent_1",
+        sortOrder: 12,
+        tags: ["enterprise"],
+      },
+    });
+    expect(result.id).toBe("client_1");
+    expect(createAuditEntry).toHaveBeenCalledWith(
+      expect.objectContaining({
+        entityType: "Client",
+        action: "CREATE",
+        entityId: "client_1",
+        userId: "user_1",
+      }),
+    );
+  });
+
+  it("updates a client without rechecking an unchanged code", async () => {
+    const findUnique = vi.fn().mockResolvedValue({
+      id: "client_1",
+      name: "Acme",
+      code: "ACME",
+      isActive: true,
+    });
+    const update = vi.fn().mockResolvedValue({
+      id: "client_1",
+      name: "Acme Updated",
+      code: "ACME",
+      isActive: true,
+    });
+
+    const result = await updateClient(
+      createContext({
+        client: {
+          findUnique,
+          update,
+        },
+      }),
+      {
+        id: "client_1",
+        data: {
+          name: "Acme Updated",
+          code: "ACME",
+        },
+      },
+    );
+
+    expect(findUnique).toHaveBeenCalledTimes(1);
+    expect(findUnique).toHaveBeenCalledWith({
+      where: { id: "client_1" },
+    });
+    expect(update).toHaveBeenCalledWith({
+      where: { id: "client_1" },
+      data: {
+        name: "Acme Updated",
+        code: "ACME",
+      },
+    });
+    expect(result.name).toBe("Acme Updated");
+    expect(createAuditEntry).toHaveBeenCalledWith(
+      expect.objectContaining({
+        entityType: "Client",
+        action: "UPDATE",
+        entityId: "client_1",
+        before: expect.objectContaining({ code: "ACME" }),
+        after: expect.objectContaining({ name: "Acme Updated" }),
+      }),
+    );
+  });
+
+  it("checks code availability when the code changes", async () => {
+    const findUnique = vi
+      .fn()
+      .mockResolvedValueOnce({
+        id: "client_1",
+        name: "Acme",
+        code: "ACME",
+        isActive: true,
+      })
+      .mockResolvedValueOnce(null);
+    const update = vi.fn().mockResolvedValue({
+      id: "client_1",
+      name: "Acme",
+      code: "ACME-2",
+      isActive: true,
+    });
+
+    await updateClient(
+      createContext({
+        client: {
+          findUnique,
+          update,
+        },
+      }),
+      {
+        id: "client_1",
+        data: {
+          code: "ACME-2",
+        },
+      },
+    );
+
+    expect(findUnique).toHaveBeenNthCalledWith(2, {
+      where: { code: "ACME-2" },
+    });
+    expect(update).toHaveBeenCalledWith({
+      where: { id: "client_1" },
+      data: { code: "ACME-2" },
+    });
+  });
+
+  it("rejects deletion while projects or child clients still exist", async () => {
+    const findUnique = vi.fn().mockResolvedValue({
+      id: "client_1",
+      name: "Acme",
+      _count: { projects: 1, children: 0 },
+    });
+    const remove = vi.fn();
+
+    await expect(
+      deleteClient(
+        createContext({
+          client: {
+            findUnique,
+            delete: remove,
+          },
+        }),
+        {
+          id: "client_1",
+        },
+      ),
+    ).rejects.toMatchObject({
+      code: "PRECONDITION_FAILED",
+      message: "Cannot delete client with 1 project(s). Deactivate instead.",
+    });
+
+    expect(remove).not.toHaveBeenCalled();
+    expect(createAuditEntry).not.toHaveBeenCalled();
+  });
+
+  it("deletes a valid client and audits the deletion", async () => {
+    const findUnique = vi.fn().mockResolvedValue({
+      id: "client_1",
+      name: "Acme",
+      _count: { projects: 0, children: 0 },
+    });
+    const remove = vi.fn().mockResolvedValue({ id: "client_1" });
+
+    const result = await deleteClient(
+      createContext({
+        client: {
+          findUnique,
+          delete: remove,
+        },
+      }),
+      {
+        id: "client_1",
+      },
+    );
+
+    expect(remove).toHaveBeenCalledWith({
+      where: { id: "client_1" },
+    });
+    expect(result).toEqual({
+      id: "client_1",
+      name: "Acme",
+      _count: { projects: 0, children: 0 },
+    });
+    expect(createAuditEntry).toHaveBeenCalledWith(
+      expect.objectContaining({
+        entityType: "Client",
+        action: "DELETE",
+        entityId: "client_1",
+        before: expect.objectContaining({ name: "Acme" }),
+      }),
+    );
+  });
+
+  it("batch-updates sort order and writes one audit per item", async () => {
+    const update = vi.fn(
+      ({ where, data }: { where: { id: string }; data: { sortOrder: number } }) =>
+        Promise.resolve({ id: where.id, sortOrder: data.sortOrder }),
+    );
+    const $transaction = vi.fn().mockResolvedValue([]);
+
+    const result = await batchUpdateClientSortOrder(
+      createContext({
+        $transaction,
+        client: {
+          update,
+        },
+      }),
+      [
+        { id: "client_1", sortOrder: 10 },
+        { id: "client_2", sortOrder: 20 },
+      ],
+    );
+
+    expect(update).toHaveBeenNthCalledWith(1, {
+      where: { id: "client_1" },
+      data: { sortOrder: 10 },
+    });
+    expect(update).toHaveBeenNthCalledWith(2, {
+      where: { id: "client_2" },
+      data: { sortOrder: 20 },
+    });
+    expect($transaction).toHaveBeenCalledTimes(1);
+    expect($transaction.mock.calls[0]?.[0]).toHaveLength(2);
+    expect(createAuditEntry).toHaveBeenCalledTimes(2);
+    expect(createAuditEntry).toHaveBeenNthCalledWith(
+      1,
+      expect.objectContaining({
+        entityId: "client_1",
+        summary: "Updated sort order",
+      }),
+    );
+    expect(createAuditEntry).toHaveBeenNthCalledWith(
+      2,
+      expect.objectContaining({
+        entityId: "client_2",
+        summary: "Updated sort order",
+      }),
+    );
+    expect(result).toEqual({ ok: true });
+  });
+
+  it("surfaces precondition failures as TRPC errors", async () => {
+    const findUnique = vi.fn().mockResolvedValue({
+      id: "client_1",
+      name: "Acme",
+      _count: { projects: 0, children: 2 },
+    });
+
+    await expect(
+      deleteClient(
+        createContext({
+          client: {
+            findUnique,
+            delete: vi.fn(),
+          },
+        }),
+        {
+          id: "client_1",
+        },
+      ),
+    ).rejects.toBeInstanceOf(TRPCError);
+  });
+});
diff --git a/packages/api/src/__tests__/client-router.test.ts b/packages/api/src/__tests__/client-router.test.ts
new file mode 100644
index 0000000..a70d90f
--- /dev/null
+++ b/packages/api/src/__tests__/client-router.test.ts
@@ -0,0 +1,282 @@
+import { SystemRole } from "@capakraken/shared";
+import { describe, expect, it, vi } from "vitest";
+
+const { createAuditEntry } = vi.hoisted(() => ({
+  createAuditEntry: vi.fn(),
+}));
+
+vi.mock("../lib/audit.js", () => ({
+  createAuditEntry,
+}));
+
+import { clientRouter } from "../router/client.js";
+import { createCallerFactory } from "../trpc.js";
+
+const createCaller = createCallerFactory(clientRouter);
+
+function createPlanningCaller(db: Record<string, unknown>) {
+  return createCaller({
+    session: {
+      user: { email: "planning@example.com", name: "Planning", image: null },
+      expires: "2099-01-01T00:00:00.000Z",
+    },
+    db: db as never,
+    dbUser: {
+      id: "user_planning",
+      systemRole: SystemRole.MANAGER,
+      permissionOverrides: null,
+    },
+    permissions: new Set(["view:planning"]),
+  });
+}
+
+function createManagerCaller(db: Record<string, unknown>) {
+  return createCaller({
+    session: {
+      user: { email: "manager@example.com", name: "Manager", image: null },
+      expires: "2099-01-01T00:00:00.000Z",
+    },
+    db: db as never,
+    dbUser: {
+      id: "user_manager",
+      systemRole: SystemRole.MANAGER,
+      permissionOverrides: null,
+    },
+  });
+}
+
+function createAdminCaller(db: Record<string, unknown>) {
+  return createCaller({
+    session: {
+      user: { email: "admin@example.com", name: "Admin", image: null },
+      expires: "2099-01-01T00:00:00.000Z",
+    },
+    db: db as never,
+    dbUser: {
+      id: "user_admin",
+      systemRole: SystemRole.ADMIN,
+      permissionOverrides: null,
+    },
+  });
+}
+
+describe("client router", () => {
+  it("lists clients with filters and count includes", async () => {
+    const findMany = vi.fn().mockResolvedValue([{ id: "client_1", name: "Acme" }]);
+
+    const caller = createPlanningCaller({
+      client: { findMany },
+    });
+    const result = await caller.list({ parentId: "parent_1", isActive: true, search: "Acme" });
+
+    expect(findMany).toHaveBeenCalledWith({
+      where: {
+        parentId: "parent_1",
+        isActive: true,
+        OR: [
+          { name: { contains: "Acme", mode: "insensitive" } },
+          { code: { contains: "Acme", mode: "insensitive" } },
+        ],
+      },
+      include: { _count: { select: { children: true, projects: true } } },
+      orderBy: [{ sortOrder: "asc" }, { name: "asc" }],
+    });
+    expect(result).toHaveLength(1);
+  });
+
+  it("returns a nested tree from ordered flat records", async () => {
+    const findMany = vi.fn().mockResolvedValue([
+      {
+        id: "client_root",
+        name: "Root",
+        code: "ROOT",
+        parentId: null,
+        isActive: true,
+        sortOrder: 10,
+        tags: [],
+        createdAt: new Date("2026-03-01T00:00:00.000Z"),
+        updatedAt: new Date("2026-03-01T00:00:00.000Z"),
+      },
+      {
+        id: "client_child",
+        name: "Child",
+        code: "CHILD",
+        parentId: "client_root",
+        isActive: true,
+        sortOrder: 20,
+        tags: [],
+        createdAt: new Date("2026-03-01T00:00:00.000Z"),
+        updatedAt: new Date("2026-03-01T00:00:00.000Z"),
+      },
+    ]);
+
+    const caller = createPlanningCaller({
+      client: { findMany },
+    });
+    const result = await caller.getTree({ isActive: true });
+
+    expect(findMany).toHaveBeenCalledWith({
+      where: { isActive: true },
+      orderBy: [{ sortOrder: "asc" }, { name: "asc" }],
+    });
+    expect(result).toEqual([
+      expect.objectContaining({
+        id: "client_root",
+        children: [expect.objectContaining({ id: "client_child" })],
+      }),
+    ]);
+  });
+
+  it("resolves a client by identifier via the protected query", async () => {
+    const findUnique = vi
+      .fn()
+      .mockResolvedValueOnce(null)
+      .mockResolvedValueOnce({
+        id: "client_1",
+        code: "ACME",
+        name: "Acme",
+        parentId: null,
+        isActive: true,
+      });
+
+    const caller = createPlanningCaller({
+      client: {
+        findUnique,
+        findFirst: vi.fn(),
+      },
+    });
+    const result = await caller.resolveByIdentifier({ identifier: " ACME " });
+
+    expect(findUnique).toHaveBeenNthCalledWith(2, {
+      where: { code: "ACME" },
+      select: {
+        id: true,
+        name: true,
+        code: true,
+        parentId: true,
+        isActive: true,
+      },
+    });
+    expect(result).toEqual({
+      id: "client_1",
+      code: "ACME",
+      name: "Acme",
+      parentId: null,
+      isActive: true,
+    });
+  });
+
+  it("creates and updates a client through the router", async () => {
+    const findUnique = vi
+      .fn()
+      .mockResolvedValueOnce({ id: "parent_1", name: "Parent" })
+      .mockResolvedValueOnce(null)
+      .mockResolvedValueOnce({
+        id: "client_1",
+        name: "Acme",
+        code: "ACME",
+        isActive: true,
+      });
+    const create = vi.fn().mockResolvedValue({
+      id: "client_1",
+      name: "Acme",
+      code: "ACME",
+      parentId: "parent_1",
+      sortOrder: 10,
+      tags: ["enterprise"],
+      isActive: true,
+    });
+    const update = vi.fn().mockResolvedValue({
+      id: "client_1",
+      name: "Acme Updated",
+      code: "ACME",
+      isActive: true,
+    });
+
+    const caller = createManagerCaller({
+      client: { findUnique, create, update },
+    });
+
+    const created = await caller.create({
+      name: "Acme",
+      code: "ACME",
+      parentId: "parent_1",
+      sortOrder: 10,
+      tags: ["enterprise"],
+    });
+    const updated = await caller.update({
+      id: "client_1",
+      data: { name: "Acme Updated", code: "ACME" },
+    });
+
+    expect(create).toHaveBeenCalledWith({
+      data: {
+        name: "Acme",
+        code: "ACME",
+        parentId: "parent_1",
+        sortOrder: 10,
+        tags: ["enterprise"],
+      },
+    });
+    expect(update).toHaveBeenCalledWith({
+      where: { id: "client_1" },
+      data: { name: "Acme Updated", code: "ACME" },
+    });
+    expect(created.id).toBe("client_1");
+    expect(updated.name).toBe("Acme Updated");
+    expect(createAuditEntry).toHaveBeenCalledTimes(2);
+  });
+
+  it("deletes a deletable client through the admin router", async () => {
+    const remove = vi.fn().mockResolvedValue({ id: "client_1" });
+
+    const caller = createAdminCaller({
+      client: {
+        findUnique: vi.fn().mockResolvedValue({
+          id: "client_1",
+          name: "Acme",
+          _count: { projects: 0, children: 0 },
+        }),
+        delete: remove,
+      },
+    });
+    const result = await caller.delete({ id: "client_1" });
+
+    expect(remove).toHaveBeenCalledWith({
+      where: { id: "client_1" },
+    });
+    expect(result).toEqual({
+      id: "client_1",
+      name: "Acme",
+      _count: { projects: 0, children: 0 },
+    });
+  });
+
+  it("batch-updates sort order through the manager router", async () => {
+    const update = vi.fn(
+      ({ where, data }: { where: { id: string }; data: { sortOrder: number } }) =>
+        Promise.resolve({ id: where.id, sortOrder: data.sortOrder }),
+    );
+    const $transaction = vi.fn().mockResolvedValue([]);
+
+    const caller = createManagerCaller({
+      $transaction,
+      client: { update },
+    });
+    const result = await caller.batchUpdateSortOrder([
+      { id: "client_1", sortOrder: 10 },
+      { id: "client_2", sortOrder: 20 },
+    ]);
+
+    expect($transaction).toHaveBeenCalledTimes(1);
+    expect(update).toHaveBeenNthCalledWith(1, {
+      where: { id: "client_1" },
+      data: { sortOrder: 10 },
+    });
+    expect(update).toHaveBeenNthCalledWith(2, {
+      where: { id: "client_2" },
+      data: { sortOrder: 20 },
+    });
+    expect(result).toEqual({ ok: true });
+  });
+});
diff --git a/packages/api/src/router/client-procedure-support.ts b/packages/api/src/router/client-procedure-support.ts
new file mode 100644
index 0000000..a354612
--- /dev/null
+++ b/packages/api/src/router/client-procedure-support.ts
@@ -0,0 +1,274 @@
+import { CreateClientSchema, UpdateClientSchema } from "@capakraken/shared";
+import { z } from "zod";
+import { findUniqueOrThrow } from "../db/helpers.js";
+import { createAuditEntry } from "../lib/audit.js";
+import type { TRPCContext } from "../trpc.js";
+import {
+  assertClientCodeAvailable,
+  assertClientDeletable,
+  buildClientCreateData,
+  buildClientListWhere,
+  buildClientTree,
+  buildClientUpdateData,
+  findClientByIdentifier,
+} from "./client-support.js";
+
+type ClientProcedureContext = Pick<TRPCContext, "db" | "dbUser">;
+
+type ClientIdentifierReadModel = {
+  id: string;
+  name: string;
+  code: string | null;
+  parentId: string | null;
+  isActive: boolean;
+};
+
+type ClientDetailReadModel = ClientIdentifierReadModel & {
+  sortOrder: number;
+  tags: string[];
+  createdAt: Date;
+  updatedAt: Date;
+  _count: {
+    projects: number;
+    children: number;
+  };
+};
+
+function withAuditUser(userId: string | undefined) {
+  return userId ? { userId } : {};
+}
+
+export const clientIdInputSchema = z.object({ id: z.string() });
+
+export const clientIdentifierInputSchema = z.object({
+  identifier: z.string().trim().min(1),
+});
+
+export const clientListInputSchema = z
+  .object({
+    parentId: z.string().nullable().optional(),
+    isActive: z.boolean().optional(),
+    search: z.string().optional(),
+  })
+  .optional();
+
+export const clientTreeInputSchema = z
+  .object({
+    isActive: z.boolean().optional(),
+  })
+  .optional();
+
+export const clientUpdateInputSchema = z.object({
+  id: z.string(),
+  data: UpdateClientSchema,
+});
+
+export const clientBatchSortOrderInputSchema = z.array(
+  z.object({
+    id: z.string(),
+    sortOrder: z.number().int(),
+  }),
+);
+
+type ClientIdInput = z.infer<typeof clientIdInputSchema>;
+type ClientIdentifierInput = z.infer<typeof clientIdentifierInputSchema>;
+type ClientListInput = z.infer<typeof clientListInputSchema>;
+type ClientTreeInput = z.infer<typeof clientTreeInputSchema>;
+type ClientCreateInput = z.infer<typeof CreateClientSchema>;
+type ClientUpdateInput = z.infer<typeof clientUpdateInputSchema>;
+type ClientBatchSortOrderInput = z.infer<typeof clientBatchSortOrderInputSchema>;
+
+export async function listClients(ctx: ClientProcedureContext, input: ClientListInput) {
+  return ctx.db.client.findMany({
+    where: buildClientListWhere(input ?? {}),
+    include: { _count: { select: { children: true, projects: true } } },
+    orderBy: [{ sortOrder: "asc" }, { name: "asc" }],
+  });
+}
+
+export async function getClientTree(ctx: ClientProcedureContext, input: ClientTreeInput) {
+  const all = await ctx.db.client.findMany({
+    where: {
+      ...(input?.isActive !== undefined ? { isActive: input.isActive } : {}),
+    },
+    orderBy: [{ sortOrder: "asc" }, { name: "asc" }],
+  });
+
+  return buildClientTree(all);
+}
+
+export async function getClientById(ctx: ClientProcedureContext, input: ClientIdInput) {
+  return findUniqueOrThrow(
+    ctx.db.client.findUnique({
+      where: { id: input.id },
+      include: {
+        parent: true,
+        children: { orderBy: { sortOrder: "asc" } },
+        _count: { select: { projects: true, children: true } },
+      },
+    }),
+    "Client",
+  );
+}
+
+export async function resolveClientByIdentifier(
+  ctx: ClientProcedureContext,
+  input: ClientIdentifierInput,
+) {
+  return findClientByIdentifier<ClientIdentifierReadModel>(ctx.db, input.identifier, {
+    select: {
+      id: true,
+      name: true,
+      code: true,
+      parentId: true,
+      isActive: true,
+    },
+  });
+}
+
+export async function getClientByIdentifier(
+  ctx: ClientProcedureContext,
+  input: ClientIdentifierInput,
+) {
+  return findClientByIdentifier<ClientDetailReadModel>(ctx.db, input.identifier, {
+    include: { _count: { select: { projects: true, children: true } } },
+  });
+}
+
+export async function createClient(ctx: ClientProcedureContext, input: ClientCreateInput) {
+  if (input.parentId) {
+    await findUniqueOrThrow(
+      ctx.db.client.findUnique({ where: { id: input.parentId } }),
+      "Parent client",
+    );
+  }
+
+  if (input.code) {
+    await assertClientCodeAvailable(ctx.db, input.code);
+  }
+
+  const created = await ctx.db.client.create({
+    data: buildClientCreateData(input),
+  });
+
+  void createAuditEntry({
+    db: ctx.db,
+    entityType: "Client",
+    entityId: created.id,
+    entityName: created.name,
+    action: "CREATE",
+    ...withAuditUser(ctx.dbUser?.id),
+    after: created as unknown as Record<string, unknown>,
+    source: "ui",
+  });
+
+  return created;
+}
+
+export async function updateClient(ctx: ClientProcedureContext, input: ClientUpdateInput) {
+  const existing = await findUniqueOrThrow(
+    ctx.db.client.findUnique({ where: { id: input.id } }),
+    "Client",
+  );
+
+  if (input.data.code && input.data.code !== existing.code) {
+    await assertClientCodeAvailable(ctx.db, input.data.code, existing.id);
+  }
+
+  const before = existing as unknown as Record<string, unknown>;
+  const updated = await ctx.db.client.update({
+    where: { id: input.id },
+    data: buildClientUpdateData(input.data),
+  });
+
+  void createAuditEntry({
+    db: ctx.db,
+    entityType: "Client",
+    entityId: updated.id,
+    entityName: updated.name,
+    action: "UPDATE",
+    ...withAuditUser(ctx.dbUser?.id),
+    before,
+    after: updated as unknown as Record<string, unknown>,
+    source: "ui",
+  });
+
+  return updated;
+}
+
+export async function deactivateClient(ctx: ClientProcedureContext, input: ClientIdInput) {
+  const updated = await ctx.db.client.update({
+    where: { id: input.id },
+    data: { isActive: false },
+  });
+
+  void createAuditEntry({
+    db: ctx.db,
+    entityType: "Client",
+    entityId: updated.id,
+    entityName: updated.name,
+    action: "UPDATE",
+    ...withAuditUser(ctx.dbUser?.id),
+    before: { isActive: true },
+    after: { isActive: false },
+    source: "ui",
+    summary: "Deactivated Client",
+  });
+
+  return updated;
+}
+
+export async function deleteClient(ctx: ClientProcedureContext, input: ClientIdInput) {
+  const client = await findUniqueOrThrow(
+    ctx.db.client.findUnique({
+      where: { id: input.id },
+      include: { _count: { select: { projects: true, children: true } } },
+    }),
+    "Client",
+  );
+
+  assertClientDeletable(client);
+  await ctx.db.client.delete({ where: { id: input.id } });
+
+  void createAuditEntry({
+    db: ctx.db,
+    entityType: "Client",
+    entityId: client.id,
+    entityName: client.name,
+    action: "DELETE",
+    ...withAuditUser(ctx.dbUser?.id),
+    before: client as unknown as Record<string, unknown>,
+    source: "ui",
+  });
+
+  return client;
+}
+
+export async function batchUpdateClientSortOrder(
+  ctx: ClientProcedureContext,
+  input: ClientBatchSortOrderInput,
+) {
+  await ctx.db.$transaction(
+    input.map((item) =>
+      ctx.db.client.update({
+        where: { id: item.id },
+        data: { sortOrder: item.sortOrder },
+      }),
+    ),
+  );
+
+  for (const item of input) {
+    void createAuditEntry({
+      db: ctx.db,
+      entityType: "Client",
+      entityId: item.id,
+      action: "UPDATE",
+      ...withAuditUser(ctx.dbUser?.id),
+      after: { sortOrder: item.sortOrder },
+      source: "ui",
+      summary: "Updated sort order",
+    });
+  }
+
+  return { ok: true };
+}
diff --git a/packages/api/src/router/client.ts b/packages/api/src/router/client.ts
index 2720bfc..35f221e 100644
--- a/packages/api/src/router/client.ts
+++ b/packages/api/src/router/client.ts
@@ -1,7 +1,4 @@
-import { CreateClientSchema, UpdateClientSchema } from "@capakraken/shared";
-import { z } from "zod";
-import { findUniqueOrThrow } from "../db/helpers.js";
-import { createAuditEntry } from "../lib/audit.js";
+import { CreateClientSchema } from "@capakraken/shared";
 import {
   adminProcedure,
   createTRPCRouter,
@@ -10,244 +7,62 @@ import {
   protectedProcedure,
 } from "../trpc.js";
 import {
-  assertClientCodeAvailable,
-  assertClientDeletable,
-  buildClientCreateData,
-  buildClientListWhere,
-  buildClientTree,
-  buildClientUpdateData,
-  findClientByIdentifier,
-} from "./client-support.js";
-
-type ClientIdentifierReadModel = {
-  id: string;
-  name: string;
-  code: string | null;
-  parentId: string | null;
-  isActive: boolean;
-};
-
-type ClientDetailReadModel = ClientIdentifierReadModel & {
-  sortOrder: number;
-  tags: string[];
-  createdAt: Date;
-  updatedAt: Date;
-  _count: {
-    projects: number;
-    children: number;
-  };
-};
+  batchUpdateClientSortOrder,
+  clientBatchSortOrderInputSchema,
+  clientIdInputSchema,
+  clientIdentifierInputSchema,
+  clientListInputSchema,
+  clientTreeInputSchema,
+  clientUpdateInputSchema,
+  createClient,
+  deactivateClient,
+  deleteClient,
+  getClientById,
+  getClientByIdentifier,
+  getClientTree,
+  listClients,
+  resolveClientByIdentifier,
+  updateClient,
+} from "./client-procedure-support.js";
 
 export const clientRouter = createTRPCRouter({
   list: planningReadProcedure
-    .input(
-      z.object({
-        parentId: z.string().nullable().optional(),
-        isActive: z.boolean().optional(),
-        search: z.string().optional(),
-      }).optional(),
-    )
-    .query(async ({ ctx, input }) => {
-      return ctx.db.client.findMany({
-        where: buildClientListWhere(input ?? {}),
-        include: { _count: { select: { children: true, projects: true } } },
-        orderBy: [{ sortOrder: "asc" }, { name: "asc" }],
-      });
-    }),
+    .input(clientListInputSchema)
+    .query(({ ctx, input }) => listClients(ctx, input)),
 
   getTree: planningReadProcedure
-    .input(z.object({ isActive: z.boolean().optional() }).optional())
-    .query(async ({ ctx, input }) => {
-      const all = await ctx.db.client.findMany({
-        where: {
-          ...(input?.isActive !== undefined ? { isActive: input.isActive } : {}),
-        },
-        orderBy: [{ sortOrder: "asc" }, { name: "asc" }],
-      });
-      return buildClientTree(all);
-    }),
+    .input(clientTreeInputSchema)
+    .query(({ ctx, input }) => getClientTree(ctx, input)),
 
   getById: planningReadProcedure
-    .input(z.object({ id: z.string() }))
-    .query(async ({ ctx, input }) => {
-      const client = await findUniqueOrThrow(
-        ctx.db.client.findUnique({
-          where: { id: input.id },
-          include: {
-            parent: true,
-            children: { orderBy: { sortOrder: "asc" } },
-            _count: { select: { projects: true, children: true } },
-          },
-        }),
-        "Client",
-      );
-      return client;
-    }),
+    .input(clientIdInputSchema)
+    .query(({ ctx, input }) => getClientById(ctx, input)),
 
   resolveByIdentifier: protectedProcedure
-    .input(z.object({ identifier: z.string().trim().min(1) }))
-    .query(async ({ ctx, input }) => {
-      return findClientByIdentifier<ClientIdentifierReadModel>(ctx.db, input.identifier, {
-        select: {
-          id: true,
-          name: true,
-          code: true,
-          parentId: true,
-          isActive: true,
-        },
-      });
-    }),
+    .input(clientIdentifierInputSchema)
+    .query(({ ctx, input }) => resolveClientByIdentifier(ctx, input)),
 
   getByIdentifier: planningReadProcedure
-    .input(z.object({ identifier: z.string().trim().min(1) }))
-    .query(async ({ ctx, input }) => {
-      return findClientByIdentifier<ClientDetailReadModel>(ctx.db, input.identifier, {
-        include: { _count: { select: { projects: true, children: true } } },
-      });
-    }),
+    .input(clientIdentifierInputSchema)
+    .query(({ ctx, input }) => getClientByIdentifier(ctx, input)),
 
   create: managerProcedure
     .input(CreateClientSchema)
-    .mutation(async ({ ctx, input }) => {
-      if (input.parentId) {
-        await findUniqueOrThrow(
-          ctx.db.client.findUnique({ where: { id: input.parentId } }),
-          "Parent client",
-        );
-      }
-
-      if (input.code) {
-        await assertClientCodeAvailable(ctx.db, input.code);
-      }
-
-      const created = await ctx.db.client.create({
-        data: buildClientCreateData(input),
-      });
-
-      void createAuditEntry({
-        db: ctx.db,
-        entityType: "Client",
-        entityId: created.id,
-        entityName: created.name,
-        action: "CREATE",
-        userId: ctx.dbUser?.id,
-        after: created as unknown as Record<string, unknown>,
-        source: "ui",
-      });
-
-      return created;
-    }),
+    .mutation(({ ctx, input }) => createClient(ctx, input)),
 
   update: managerProcedure
-    .input(z.object({ id: z.string(), data: UpdateClientSchema }))
-    .mutation(async ({ ctx, input }) => {
-      const existing = await findUniqueOrThrow(
-        ctx.db.client.findUnique({ where: { id: input.id } }),
-        "Client",
-      );
-
-      if (input.data.code && input.data.code !== existing.code) {
-        await assertClientCodeAvailable(ctx.db, input.data.code, existing.id);
-      }
-
-      const before = existing as unknown as Record<string, unknown>;
-
-      const updated = await ctx.db.client.update({
-        where: { id: input.id },
-        data: buildClientUpdateData(input.data),
-      });
-
-      void createAuditEntry({
-        db: ctx.db,
-        entityType: "Client",
-        entityId: updated.id,
-        entityName: updated.name,
-        action: "UPDATE",
-        userId: ctx.dbUser?.id,
-        before,
-        after: updated as unknown as Record<string, unknown>,
-        source: "ui",
-      });
-
-      return updated;
-    }),
+    .input(clientUpdateInputSchema)
+    .mutation(({ ctx, input }) => updateClient(ctx, input)),
 
   deactivate: managerProcedure
-    .input(z.object({ id: z.string() }))
-    .mutation(async ({ ctx, input }) => {
-      const updated = await ctx.db.client.update({
-        where: { id: input.id },
-        data: { isActive: false },
-      });
-
-      void createAuditEntry({
-        db: ctx.db,
-        entityType: "Client",
-        entityId: updated.id,
-        entityName: updated.name,
-        action: "UPDATE",
-        userId: ctx.dbUser?.id,
-        before: { isActive: true },
-        after: { isActive: false },
-        source: "ui",
-        summary: "Deactivated Client",
-      });
-
-      return updated;
-    }),
+    .input(clientIdInputSchema)
+    .mutation(({ ctx, input }) => deactivateClient(ctx, input)),
 
   delete: adminProcedure
-    .input(z.object({ id: z.string() }))
-    .mutation(async ({ ctx, input }) => {
-      const client = await findUniqueOrThrow(
-        ctx.db.client.findUnique({
-          where: { id: input.id },
-          include: { _count: { select: { projects: true, children: true } } },
-        }),
-        "Client",
-      );
-      assertClientDeletable(client);
-      await ctx.db.client.delete({ where: { id: input.id } });
-
-      void createAuditEntry({
-        db: ctx.db,
-        entityType: "Client",
-        entityId: client.id,
-        entityName: client.name,
-        action: "DELETE",
-        userId: ctx.dbUser?.id,
-        before: client as unknown as Record<string, unknown>,
-        source: "ui",
-      });
-
-      return client;
-    }),
+    .input(clientIdInputSchema)
+    .mutation(({ ctx, input }) => deleteClient(ctx, input)),
 
   batchUpdateSortOrder: managerProcedure
-    .input(z.array(z.object({ id: z.string(), sortOrder: z.number().int() })))
-    .mutation(async ({ ctx, input }) => {
-      await ctx.db.$transaction(
-        input.map((item) =>
-          ctx.db.client.update({
-            where: { id: item.id },
-            data: { sortOrder: item.sortOrder },
-          }),
-        ),
-      );
-
-      for (const item of input) {
-        void createAuditEntry({
-          db: ctx.db,
-          entityType: "Client",
-          entityId: item.id,
-          action: "UPDATE",
-          userId: ctx.dbUser?.id,
-          after: { sortOrder: item.sortOrder },
-          source: "ui",
-          summary: "Updated sort order",
-        });
-      }
-
-      return { ok: true };
-    }),
+    .input(clientBatchSortOrderInputSchema)
+    .mutation(({ ctx, input }) => batchUpdateClientSortOrder(ctx, input)),
 });