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/core/test/lib/tool.ts

@@ -46,24 +46,11 @@ export const registerToolPlugin = <R>(plugin: {
     const context = host({
       tool: {
         transform: (callback) =>
-          Effect.gen(function* () {
-            const registrations: Array<{
-              readonly name: string
-              readonly tool: Tool.AnyTool
-              readonly options?: Tool.RegisterOptions
-            }> = []
-            callback({
-              add: (name, tool, options) => {
-                registrations.push({ name, tool, ...(options ? { options } : {}) })
-              },
-            })
-            yield* Effect.forEach(
-              registrations,
-              (registration) => tools.register({ [registration.name]: registration.tool }, registration.options),
-              { discard: true },
-            ).pipe(Effect.orDie)
-            return { dispose: Effect.void }
-          }),
+          Effect.forEach(
+            Tool.fromDraft(callback),
+            ({ name, tool, options }) => tools.register({ [name]: tool }, options),
+            { discard: true },
+          ).pipe(Effect.orDie, Effect.as({ dispose: Effect.void })),
         hook: () => Effect.die("registerToolPlugin does not support tool hooks"),
       },
     })

packages/core/test/plugin.test.ts

@@ -274,7 +274,7 @@ describe("PluginV2", () => {
     }),
   )
 
-  it.effect("groups tool names and routes codemode registrations through execute", () =>
+  it.effect("namespaces tool names and routes codemode registrations through execute", () =>
     Effect.gen(function* () {
       const plugins = yield* PluginV2.Service
       const registry = yield* ToolRegistry.Service
@@ -286,13 +286,13 @@ describe("PluginV2", () => {
           execute: () => Effect.succeed({ ok: true }),
         })
       const plugin = EffectPlugin.define({
-        id: "grouped-tools",
+        id: "namespaced-tools",
         effect: (ctx) =>
           ctx.tool
             .transform((draft) => {
               draft.add("plain", tool("Plain"), { codemode: false })
-              draft.add("look/up", tool("Lookup"), { group: "context 7", codemode: false })
-              draft.add("search", tool("Search"), { group: "context 7" })
+              draft.add("look/up", tool("Lookup"), { namespace: "context 7", codemode: false })
+              draft.add("search", tool("Search"), { namespace: "context 7" })
             })
             .pipe(Effect.orDie),
       })
@@ -307,6 +307,41 @@ describe("PluginV2", () => {
     }),
   )
 
+  it.effect("accepts flat Effect draft declarations with namespace", () =>
+    Effect.gen(function* () {
+      const plugins = yield* PluginV2.Service
+      const registry = yield* ToolRegistry.Service
+      const plugin = EffectPlugin.define({
+        id: "flat-tools",
+        effect: (ctx) =>
+          ctx.tool
+            .transform((draft) => {
+              draft.add({
+                name: "send",
+                namespace: "slack",
+                description: "Send a Slack message",
+                input: Schema.Struct({ text: Schema.String }),
+                output: Schema.Struct({ sent: Schema.Boolean }),
+                execute: () => Effect.succeed({ sent: true }),
+              })
+              draft.add({
+                name: "edit",
+                codemode: false,
+                description: "Edit a file",
+                input: Schema.Struct({}),
+                output: Schema.Struct({ ok: Schema.Boolean }),
+                execute: () => Effect.succeed({ ok: true }),
+              })
+            })
+            .pipe(Effect.orDie),
+      })
+
+      yield* plugins.activate([versioned(plugin)])
+
+      expect((yield* registry.materialize()).definitions.map((tool) => tool.name)).toEqual(["edit", "execute"])
+    }),
+  )
+
   it.effect("fires before/after tool hooks with mutable events around settlement", () =>
     Effect.gen(function* () {
       const plugins = yield* PluginV2.Service

packages/core/test/plugin/promise.test.ts

@@ -135,7 +135,7 @@ describe("fromPromise", () => {
           await ctx.tool.transform((tools) => {
             tools.add({
               name: "hello",
-              options: { codemode: false },
+              codemode: false,
               description: "Hello",
               input: Schema.Struct({ name: Schema.String }),
               output: Schema.String,