feat(06-01): add athena council execution tool

- add athena_council tool scaffolding and runtime execution bridge

- poll background tasks before returning synthesized council output

src/tools/athena-council/tools.test.ts

@@ -0,0 +1,62 @@
+/// <reference types="bun-types" />
+
+import { describe, expect, test } from "bun:test"
+import type { BackgroundManager } from "../../features/background-agent"
+import { ATHENA_COUNCIL_TOOL_DESCRIPTION } from "./constants"
+import { createAthenaCouncilTool } from "./tools"
+
+const mockManager = {
+  getTask: () => undefined,
+  launch: async () => {
+    throw new Error("launch should not be called in config validation tests")
+  },
+} as unknown as BackgroundManager
+
+const mockToolContext = {
+  sessionID: "session-1",
+  messageID: "message-1",
+  agent: "athena",
+  abort: new AbortController().signal,
+}
+
+describe("createAthenaCouncilTool", () => {
+  test("returns error when councilConfig is undefined", async () => {
+    // #given
+    const athenaCouncilTool = createAthenaCouncilTool({
+      backgroundManager: mockManager,
+      councilConfig: undefined,
+    })
+
+    // #when
+    const result = await athenaCouncilTool.execute({ question: "How should we proceed?" }, mockToolContext)
+
+    // #then
+    expect(result).toBe("Athena council not configured. Add agents.athena.council.members to your config.")
+  })
+
+  test("returns error when councilConfig has empty members", async () => {
+    // #given
+    const athenaCouncilTool = createAthenaCouncilTool({
+      backgroundManager: mockManager,
+      councilConfig: { members: [] },
+    })
+
+    // #when
+    const result = await athenaCouncilTool.execute({ question: "Any concerns?" }, mockToolContext)
+
+    // #then
+    expect(result).toBe("Athena council not configured. Add agents.athena.council.members to your config.")
+  })
+
+  test("uses expected description and question arg schema", () => {
+    // #given
+    const athenaCouncilTool = createAthenaCouncilTool({
+      backgroundManager: mockManager,
+      councilConfig: { members: [{ model: "openai/gpt-5.3-codex" }] },
+    })
+
+    // #then
+    expect(athenaCouncilTool.description).toBe(ATHENA_COUNCIL_TOOL_DESCRIPTION)
+    expect((athenaCouncilTool as { args: Record<string, unknown> }).args.question).toBeDefined()
+  })
+})