{
  action: "list" | "get" | "issues" | "merge_requests" | "burndown",
  
  // Common - scope selection
  scope: "project" | "group",
  projectId?: string,
  groupId?: string,
  
  // For "list" action
  state?: "active" | "closed" | "all",
  title?: string,
  search?: string,
  include_parent_milestones?: boolean,
  include_ancestors?: boolean,
  updated_before?: string,
  updated_after?: string,
  
  // For "get", "issues", "merge_requests", "burndown"
  milestoneId?: number,
  
  // Pagination for list/issues/merge_requests
  per_page?: number,
  page?: number
}

{
  action: "create" | "update" | "delete" | "promote",
  
  // Common - scope selection
  scope: "project" | "group",
  projectId?: string,
  groupId?: string,
  
  // For "update", "delete", "promote"
  milestoneId?: number,
  
  // For "create" and "update"
  title?: string,
  description?: string,
  start_date?: string,        // YYYY-MM-DD
  due_date?: string,          // YYYY-MM-DD
  state_event?: "close" | "activate"
}

// browse_milestones - READ operations
const BrowseMilestonesSchema = z.object({
  action: z.enum(["list", "get", "issues", "merge_requests", "burndown"]),
  scope: z.enum(["project", "group"]),
  projectId: z.string().optional(),
  groupId: z.string().optional(),
  // list-specific
  state: z.enum(["active", "closed", "all"]).optional(),
  title: z.string().optional(),
  search: z.string().optional(),
  include_parent_milestones: z.boolean().optional(),
  include_ancestors: z.boolean().optional(),
  updated_before: z.string().optional(),
  updated_after: z.string().optional(),
  // get/issues/merge_requests/burndown specific
  milestoneId: z.number().optional(),
  // pagination
  per_page: z.number().optional(),
  page: z.number().optional(),
}).refine(
  (data) => data.scope !== "project" || data.projectId !== undefined,
  { message: "projectId is required when scope is 'project'", path: ["projectId"] }
).refine(
  (data) => data.scope !== "group" || data.groupId !== undefined,
  { message: "groupId is required when scope is 'group'", path: ["groupId"] }
).refine(
  (data) => data.action === "list" || data.milestoneId !== undefined,
  { message: "milestoneId is required for get/issues/merge_requests/burndown actions", path: ["milestoneId"] }
);

// manage_milestone - WRITE operations
const ManageMilestoneSchema = z.object({
  action: z.enum(["create", "update", "delete", "promote"]),
  scope: z.enum(["project", "group"]),
  projectId: z.string().optional(),
  groupId: z.string().optional(),
  milestoneId: z.number().optional(),
  title: z.string().optional(),
  description: z.string().optional(),
  start_date: z.string().optional(),
  due_date: z.string().optional(),
  state_event: z.enum(["close", "activate"]).optional(),
}).refine(
  (data) => data.scope !== "project" || data.projectId !== undefined,
  { message: "projectId is required when scope is 'project'", path: ["projectId"] }
).refine(
  (data) => data.scope !== "group" || data.groupId !== undefined,
  { message: "groupId is required when scope is 'group'", path: ["groupId"] }
).refine(
  (data) => data.action === "create" || data.milestoneId !== undefined,
  { message: "milestoneId is required for update/delete/promote actions", path: ["milestoneId"] }
).refine(
  (data) => data.action !== "create" || data.title !== undefined,
  { message: "title is required for 'create' action", path: ["title"] }
);