feat(plugin): flat tool draft with namespace

Effect draft.add accepts flat tool objects matching Promise ergonomics.
Migrate the tool grouping concept fully to namespace: rename MCP's group
helper/registration to namespace and thread namespace through the flat
Effect and Promise draft declarations.

packages/plugin/src/v2/effect/tool.ts

@@ -123,6 +123,17 @@ export function make(config: Config<any, any, any> | DynamicConfig): AnyTool {
   return makeTyped(config)
 }
 
+/**
+ * Split a flat tool declaration into its registration name, opaque Tool value,
+ * and registration options. Narrowing on `jsonSchema` selects the matching
+ * constructor, so no cast is needed to build the Tool from the flat union.
+ */
+export function fromFlat(flat: FlatDefinition<any, any, any> | FlatDynamicDefinition) {
+  const { name, namespace, codemode, ...config } = flat
+  const tool = "jsonSchema" in config ? makeDynamic(config) : makeTyped(config)
+  return { name, tool, options: { namespace, codemode } satisfies RegisterOptions }
+}
+
 function makeTyped<
   Input extends SchemaType<any>,
   Output extends SchemaType<any>,
@@ -212,14 +223,14 @@ export const validateName = (name: string) =>
     ? Effect.void
     : Effect.fail(new RegistrationError({ name, message: `Invalid tool name: ${name}` }))
 
-export const registrationEntries = (tools: Readonly<Record<string, AnyTool>>, group?: string) =>
+export const registrationEntries = (tools: Readonly<Record<string, AnyTool>>, namespace?: string) =>
   Object.entries(tools).map(([name, tool]) => {
     const normalized = name.replace(/[^a-zA-Z0-9_-]/g, "_")
-    const parent = group?.replace(/[^a-zA-Z0-9_-]/g, "_")
+    const parent = namespace?.replace(/[^a-zA-Z0-9_-]/g, "_")
     return {
       key: parent === undefined ? normalized : `${parent}_${normalized}`,
       name: normalized,
-      group: parent,
+      namespace: parent,
       tool,
     }
   })
@@ -271,15 +282,68 @@ export interface ToolExecuteAfterEvent {
 }
 
 export interface RegisterOptions {
-  readonly group?: string
+  /** Dotted CodeMode path prefix, e.g. "slack.admin". */
+  readonly namespace?: string
   /** Defaults to true. False exposes the tool directly to the provider. */
   readonly codemode?: boolean
 }
 
+export type FlatDefinition<
+  Input extends SchemaType<any>,
+  Output extends SchemaType<any>,
+  Structured extends SchemaType<any> = Output,
+> = {
+  readonly name: string
+  readonly namespace?: string
+  readonly codemode?: boolean
+  readonly description: string
+  readonly input: Input
+  readonly output: Output
+  readonly structured?: Structured
+  readonly toStructuredOutput?: Config<Input, Output, Structured>["toStructuredOutput"]
+  readonly execute: Config<Input, Output, Structured>["execute"]
+  readonly toModelOutput?: Config<Input, Output, Structured>["toModelOutput"]
+}
+
+export type FlatDynamicDefinition = {
+  readonly name: string
+  readonly namespace?: string
+  readonly codemode?: boolean
+  readonly description: string
+  readonly jsonSchema: JsonSchema.JsonSchema
+  readonly outputSchema?: JsonSchema.JsonSchema
+  readonly execute: DynamicConfig["execute"]
+}
+
 export interface ToolDraft {
+  add<
+    Input extends SchemaType<any>,
+    Output extends SchemaType<any>,
+    Structured extends SchemaType<any> = Output,
+  >(tool: FlatDefinition<Input, Output, Structured>): void
+  add(tool: FlatDynamicDefinition): void
   add(name: string, tool: AnyTool, options?: RegisterOptions): void
 }
 
+export type Registration = {
+  readonly name: string
+  readonly tool: AnyTool
+  readonly options?: RegisterOptions
+}
+
+/** Run a draft callback and collect the tools it declared, in registration order. */
+export function fromDraft(callback: (draft: ToolDraft) => void) {
+  const registrations: Array<Registration> = []
+  const add = (
+    nameOrTool: string | FlatDefinition<any, any, any> | FlatDynamicDefinition,
+    tool?: AnyTool,
+    options?: RegisterOptions,
+  ) =>
+    registrations.push(typeof nameOrTool === "string" ? { name: nameOrTool, tool: tool!, options } : fromFlat(nameOrTool))
+  callback({ add })
+  return registrations
+}
+
 export interface ToolHooks {
   readonly "execute.before": ToolExecuteBeforeEvent
   readonly "execute.after": ToolExecuteAfterEvent

packages/plugin/src/v2/promise/tool.ts

@@ -16,7 +16,8 @@ export type Definition<
   Structured extends SchemaType<any> = Output,
 > = {
   readonly name: string
-  readonly options?: RegisterOptions
+  readonly namespace?: string
+  readonly codemode?: boolean
   readonly description: string
   readonly input: Input
   readonly output: Output
@@ -37,7 +38,8 @@ export type Definition<
 
 export type DynamicDefinition = {
   readonly name: string
-  readonly options?: RegisterOptions
+  readonly namespace?: string
+  readonly codemode?: boolean
   readonly description: string
   readonly jsonSchema: JsonSchema.JsonSchema
   readonly outputSchema?: JsonSchema.JsonSchema
@@ -67,12 +69,6 @@ export interface ToolExecuteAfterEvent {
   outputPaths?: ReadonlyArray<string>
 }
 
-export interface RegisterOptions {
-  readonly group?: string
-  /** Defaults to true. False exposes the tool directly to the provider. */
-  readonly codemode?: boolean
-}
-
 export interface ToolDraft {
   add<
     Input extends SchemaType<any>,