diff --git a/src/tools/agent-teams/name-validation.test.ts b/src/tools/agent-teams/name-validation.test.ts
new file mode 100644
index 00000000..9dd0b124
--- /dev/null
+++ b/src/tools/agent-teams/name-validation.test.ts
@@ -0,0 +1,58 @@
+/// <reference types="bun-types" />
+import { describe, expect, test } from "bun:test"
+import { validateAgentName, validateTeamName } from "./name-validation"
+
+describe("agent-teams name validation", () => {
+  test("accepts valid team names", () => {
+    //#given
+    const validNames = ["team_1", "alpha-team", "A1"]
+
+    //#when
+    const result = validNames.map(validateTeamName)
+
+    //#then
+    expect(result).toEqual([null, null, null])
+  })
+
+  test("rejects invalid and empty team names", () => {
+    //#given
+    const blank = ""
+    const invalid = "team space"
+    const tooLong = "a".repeat(65)
+
+    //#when
+    const blankResult = validateTeamName(blank)
+    const invalidResult = validateTeamName(invalid)
+    const tooLongResult = validateTeamName(tooLong)
+
+    //#then
+    expect(blankResult).toBe("team_name_required")
+    expect(invalidResult).toBe("team_name_invalid")
+    expect(tooLongResult).toBe("team_name_too_long")
+  })
+
+  test("rejects reserved teammate name", () => {
+    //#given
+    const reservedName = "team-lead"
+
+    //#when
+    const result = validateAgentName(reservedName)
+
+    //#then
+    expect(result).toBe("agent_name_reserved")
+  })
+
+  test("validates regular agent names", () => {
+    //#given
+    const valid = "worker_1"
+    const invalid = "worker one"
+
+    //#when
+    const validResult = validateAgentName(valid)
+    const invalidResult = validateAgentName(invalid)
+
+    //#then
+    expect(validResult).toBeNull()
+    expect(invalidResult).toBe("agent_name_invalid")
+  })
+})
diff --git a/src/tools/agent-teams/paths.test.ts b/src/tools/agent-teams/paths.test.ts
new file mode 100644
index 00000000..ab5de9a1
--- /dev/null
+++ b/src/tools/agent-teams/paths.test.ts
@@ -0,0 +1,80 @@
+/// <reference types="bun-types" />
+import { afterEach, beforeEach, describe, expect, test } from "bun:test"
+import { mkdtempSync, rmSync } from "node:fs"
+import { tmpdir } from "node:os"
+import { join } from "node:path"
+import {
+  getAgentTeamsRootDir,
+  getTeamConfigPath,
+  getTeamDir,
+  getTeamInboxDir,
+  getTeamInboxPath,
+  getTeamTaskDir,
+  getTeamTaskPath,
+  getTeamsRootDir,
+  getTeamTasksRootDir,
+} from "./paths"
+
+describe("agent-teams paths", () => {
+  let originalCwd: string
+  let tempProjectDir: string
+
+  beforeEach(() => {
+    originalCwd = process.cwd()
+    tempProjectDir = mkdtempSync(join(tmpdir(), "agent-teams-paths-"))
+    process.chdir(tempProjectDir)
+  })
+
+  afterEach(() => {
+    process.chdir(originalCwd)
+    rmSync(tempProjectDir, { recursive: true, force: true })
+  })
+
+  test("uses project-local .sisyphus directory as storage root", () => {
+    //#given
+    const expectedRoot = join(tempProjectDir, ".sisyphus", "agent-teams")
+
+    //#when
+    const root = getAgentTeamsRootDir()
+
+    //#then
+    expect(root).toBe(expectedRoot)
+  })
+
+  test("builds expected teams and tasks root directories", () => {
+    //#given
+    const expectedRoot = join(tempProjectDir, ".sisyphus", "agent-teams")
+
+    //#when
+    const teamsRoot = getTeamsRootDir()
+    const tasksRoot = getTeamTasksRootDir()
+
+    //#then
+    expect(teamsRoot).toBe(join(expectedRoot, "teams"))
+    expect(tasksRoot).toBe(join(expectedRoot, "tasks"))
+  })
+
+  test("builds team-scoped config, inbox, and task file paths", () => {
+    //#given
+    const teamName = "alpha_team"
+    const agentName = "worker_1"
+    const taskId = "T-123"
+    const expectedTeamDir = join(getTeamsRootDir(), teamName)
+
+    //#when
+    const teamDir = getTeamDir(teamName)
+    const configPath = getTeamConfigPath(teamName)
+    const inboxDir = getTeamInboxDir(teamName)
+    const inboxPath = getTeamInboxPath(teamName, agentName)
+    const taskDir = getTeamTaskDir(teamName)
+    const taskPath = getTeamTaskPath(teamName, taskId)
+
+    //#then
+    expect(teamDir).toBe(expectedTeamDir)
+    expect(configPath).toBe(join(expectedTeamDir, "config.json"))
+    expect(inboxDir).toBe(join(expectedTeamDir, "inboxes"))
+    expect(inboxPath).toBe(join(expectedTeamDir, "inboxes", `${agentName}.json`))
+    expect(taskDir).toBe(join(getTeamTasksRootDir(), teamName))
+    expect(taskPath).toBe(join(getTeamTasksRootDir(), teamName, `${taskId}.json`))
+  })
+})
diff --git a/src/tools/agent-teams/team-task-dependency.test.ts b/src/tools/agent-teams/team-task-dependency.test.ts
new file mode 100644
index 00000000..0aea66d8
--- /dev/null
+++ b/src/tools/agent-teams/team-task-dependency.test.ts
@@ -0,0 +1,94 @@
+/// <reference types="bun-types" />
+import { describe, expect, test } from "bun:test"
+import {
+  addPendingEdge,
+  createPendingEdgeMap,
+  ensureDependenciesCompleted,
+  ensureForwardStatusTransition,
+  wouldCreateCycle,
+} from "./team-task-dependency"
+import type { TeamTask, TeamTaskStatus } from "./types"
+
+function createTask(id: string, status: TeamTaskStatus, blockedBy: string[] = []): TeamTask {
+  return {
+    id,
+    subject: `Task ${id}`,
+    description: `Description ${id}`,
+    status,
+    blocks: [],
+    blockedBy,
+  }
+}
+
+describe("agent-teams task dependency utilities", () => {
+  test("detects cycle from existing blockedBy chain", () => {
+    //#given
+    const tasks = new Map<string, TeamTask>([
+      ["A", createTask("A", "pending", ["B"])],
+      ["B", createTask("B", "pending")],
+    ])
+    const pending = createPendingEdgeMap()
+    const readTask = (id: string) => tasks.get(id) ?? null
+
+    //#when
+    const hasCycle = wouldCreateCycle("B", "A", pending, readTask)
+
+    //#then
+    expect(hasCycle).toBe(true)
+  })
+
+  test("detects cycle from pending edge map", () => {
+    //#given
+    const tasks = new Map<string, TeamTask>([["A", createTask("A", "pending")]])
+    const pending = createPendingEdgeMap()
+    addPendingEdge(pending, "A", "B")
+    const readTask = (id: string) => tasks.get(id) ?? null
+
+    //#when
+    const hasCycle = wouldCreateCycle("B", "A", pending, readTask)
+
+    //#then
+    expect(hasCycle).toBe(true)
+  })
+
+  test("returns false when dependency graph has no cycle", () => {
+    //#given
+    const tasks = new Map<string, TeamTask>([
+      ["A", createTask("A", "pending")],
+      ["B", createTask("B", "pending", ["A"])],
+    ])
+    const pending = createPendingEdgeMap()
+    const readTask = (id: string) => tasks.get(id) ?? null
+
+    //#when
+    const hasCycle = wouldCreateCycle("C", "B", pending, readTask)
+
+    //#then
+    expect(hasCycle).toBe(false)
+  })
+
+  test("allows forward status transitions and blocks backward transitions", () => {
+    //#then
+    expect(() => ensureForwardStatusTransition("pending", "in_progress")).not.toThrow()
+    expect(() => ensureForwardStatusTransition("in_progress", "completed")).not.toThrow()
+    expect(() => ensureForwardStatusTransition("in_progress", "pending")).toThrow(
+      "invalid_status_transition:in_progress->pending",
+    )
+  })
+
+  test("requires blockers to be completed for in_progress/completed", () => {
+    //#given
+    const tasks = new Map<string, TeamTask>([
+      ["done", createTask("done", "completed")],
+      ["wait", createTask("wait", "pending")],
+    ])
+    const readTask = (id: string) => tasks.get(id) ?? null
+
+    //#then
+    expect(() => ensureDependenciesCompleted("pending", ["wait"], readTask)).not.toThrow()
+    expect(() => ensureDependenciesCompleted("in_progress", ["done"], readTask)).not.toThrow()
+    expect(() => ensureDependenciesCompleted("completed", ["wait"], readTask)).toThrow(
+      "blocked_by_incomplete:wait:pending",
+    )
+  })
+})
diff --git a/src/tools/agent-teams/tools.functional.test.ts b/src/tools/agent-teams/tools.functional.test.ts
new file mode 100644
index 00000000..ab3cbbf9
--- /dev/null
+++ b/src/tools/agent-teams/tools.functional.test.ts
@@ -0,0 +1,345 @@
+/// <reference types="bun-types" />
+import { afterEach, beforeEach, describe, expect, test } from "bun:test"
+import { existsSync, mkdtempSync, rmSync } from "node:fs"
+import { tmpdir } from "node:os"
+import { join } from "node:path"
+import type { BackgroundManager } from "../../features/background-agent"
+import { createAgentTeamsTools } from "./tools"
+import { getTeamDir, getTeamInboxPath, getTeamTaskDir } from "./paths"
+
+interface LaunchCall {
+  description: string
+  prompt: string
+  agent: string
+  parentSessionID: string
+  parentMessageID: string
+  parentAgent?: string
+  model?: {
+    providerID: string
+    modelID: string
+  }
+}
+
+interface ResumeCall {
+  sessionId: string
+  prompt: string
+  parentSessionID: string
+  parentMessageID: string
+  parentAgent?: string
+}
+
+interface CancelCall {
+  taskId: string
+  options?: unknown
+}
+
+interface MockManagerHandles {
+  manager: BackgroundManager
+  launchCalls: LaunchCall[]
+  resumeCalls: ResumeCall[]
+  cancelCalls: CancelCall[]
+}
+
+interface TestToolContext {
+  sessionID: string
+  messageID: string
+  agent: string
+  abort: AbortSignal
+}
+
+function createMockManager(): MockManagerHandles {
+  const launchCalls: LaunchCall[] = []
+  const resumeCalls: ResumeCall[] = []
+  const cancelCalls: CancelCall[] = []
+  const launchedTasks = new Map<string, { id: string; sessionID: string }>()
+  let launchCount = 0
+
+  const manager = {
+    launch: async (args: LaunchCall) => {
+      launchCount += 1
+      launchCalls.push(args)
+      const task = { id: `bg-${launchCount}`, sessionID: `ses-worker-${launchCount}` }
+      launchedTasks.set(task.id, task)
+      return task
+    },
+    getTask: (taskId: string) => launchedTasks.get(taskId),
+    resume: async (args: ResumeCall) => {
+      resumeCalls.push(args)
+      return { id: `resume-${resumeCalls.length}` }
+    },
+    cancelTask: async (taskId: string, options?: unknown) => {
+      cancelCalls.push({ taskId, options })
+      return true
+    },
+  } as unknown as BackgroundManager
+
+  return { manager, launchCalls, resumeCalls, cancelCalls }
+}
+
+function createContext(): TestToolContext {
+  return {
+    sessionID: "ses-main",
+    messageID: "msg-main",
+    agent: "sisyphus",
+    abort: new AbortController().signal,
+  }
+}
+
+async function executeJsonTool(
+  tools: ReturnType<typeof createAgentTeamsTools>,
+  toolName: keyof ReturnType<typeof createAgentTeamsTools>,
+  args: Record<string, unknown>,
+  context: TestToolContext,
+): Promise<unknown> {
+  const output = await tools[toolName].execute(args, context)
+  return JSON.parse(output)
+}
+
+describe("agent-teams tools functional", () => {
+  let originalCwd: string
+  let tempProjectDir: string
+
+  beforeEach(() => {
+    originalCwd = process.cwd()
+    tempProjectDir = mkdtempSync(join(tmpdir(), "agent-teams-tools-"))
+    process.chdir(tempProjectDir)
+  })
+
+  afterEach(() => {
+    process.chdir(originalCwd)
+    rmSync(tempProjectDir, { recursive: true, force: true })
+  })
+
+  test("team_create/read_config/delete work with project-local storage", async () => {
+    //#given
+    const { manager } = createMockManager()
+    const tools = createAgentTeamsTools(manager)
+    const context = createContext()
+
+    //#when
+    const created = await executeJsonTool(
+      tools,
+      "team_create",
+      { team_name: "core", description: "Core team" },
+      context,
+    ) as { team_name: string; team_file_path: string; lead_agent_id: string }
+
+    //#then
+    expect(created.team_name).toBe("core")
+    expect(created.lead_agent_id).toBe("team-lead@core")
+    expect(created.team_file_path).toBe(join(tempProjectDir, ".sisyphus", "agent-teams", "teams", "core", "config.json"))
+    expect(existsSync(created.team_file_path)).toBe(true)
+    expect(existsSync(getTeamInboxPath("core", "team-lead"))).toBe(true)
+
+    //#when
+    const config = await executeJsonTool(tools, "read_config", { team_name: "core" }, context) as {
+      name: string
+      members: Array<{ name: string }>
+    }
+
+    //#then
+    expect(config.name).toBe("core")
+    expect(config.members.map((member) => member.name)).toEqual(["team-lead"])
+
+    //#when
+    const deleted = await executeJsonTool(tools, "team_delete", { team_name: "core" }, context) as {
+      success: boolean
+    }
+
+    //#then
+    expect(deleted.success).toBe(true)
+    expect(existsSync(getTeamDir("core"))).toBe(false)
+    expect(existsSync(getTeamTaskDir("core"))).toBe(false)
+  })
+
+  test("task tools create/update/get/list and emit assignment inbox message", async () => {
+    //#given
+    const { manager } = createMockManager()
+    const tools = createAgentTeamsTools(manager)
+    const context = createContext()
+
+    await executeJsonTool(tools, "team_create", { team_name: "core" }, context)
+
+    //#when
+    const createdTask = await executeJsonTool(
+      tools,
+      "team_task_create",
+      {
+        team_name: "core",
+        subject: "Draft release notes",
+        description: "Prepare release notes for next publish.",
+      },
+      context,
+    ) as { id: string; status: string }
+
+    //#then
+    expect(createdTask.id).toMatch(/^T-[a-f0-9-]+$/)
+    expect(createdTask.status).toBe("pending")
+
+    //#when
+    const updatedTask = await executeJsonTool(
+      tools,
+      "team_task_update",
+      {
+        team_name: "core",
+        task_id: createdTask.id,
+        owner: "worker_1",
+        status: "in_progress",
+      },
+      context,
+    ) as { owner?: string; status: string }
+
+    //#then
+    expect(updatedTask.owner).toBe("worker_1")
+    expect(updatedTask.status).toBe("in_progress")
+
+    //#when
+    const fetchedTask = await executeJsonTool(
+      tools,
+      "team_task_get",
+      { team_name: "core", task_id: createdTask.id },
+      context,
+    ) as { id: string; owner?: string }
+    const listedTasks = await executeJsonTool(tools, "team_task_list", { team_name: "core" }, context) as Array<{ id: string }>
+    const inbox = await executeJsonTool(
+      tools,
+      "read_inbox",
+      {
+        team_name: "core",
+        agent_name: "worker_1",
+        unread_only: true,
+        mark_as_read: false,
+      },
+      context,
+    ) as Array<{ summary?: string; text: string }>
+
+    //#then
+    expect(fetchedTask.id).toBe(createdTask.id)
+    expect(fetchedTask.owner).toBe("worker_1")
+    expect(listedTasks.some((task) => task.id === createdTask.id)).toBe(true)
+    expect(inbox.some((message) => message.summary === "task_assignment")).toBe(true)
+    const assignment = inbox.find((message) => message.summary === "task_assignment")
+    expect(assignment).toBeDefined()
+    const payload = JSON.parse(assignment!.text) as { type: string; taskId: string }
+    expect(payload.type).toBe("task_assignment")
+    expect(payload.taskId).toBe(createdTask.id)
+  })
+
+  test("spawn_teammate + send_message + force_kill_teammate execute end-to-end", async () => {
+    //#given
+    const { manager, launchCalls, resumeCalls, cancelCalls } = createMockManager()
+    const tools = createAgentTeamsTools(manager)
+    const context = createContext()
+
+    await executeJsonTool(tools, "team_create", { team_name: "core" }, context)
+
+    //#when
+    const spawned = await executeJsonTool(
+      tools,
+      "spawn_teammate",
+      {
+        team_name: "core",
+        name: "worker_1",
+        prompt: "Handle release prep",
+      },
+      context,
+    ) as { name: string; session_id: string; task_id: string }
+
+    //#then
+    expect(spawned.name).toBe("worker_1")
+    expect(spawned.session_id).toBe("ses-worker-1")
+    expect(spawned.task_id).toBe("bg-1")
+    expect(launchCalls).toHaveLength(1)
+    expect(launchCalls[0]).toMatchObject({
+      description: "[team:core] worker_1",
+      agent: "sisyphus-junior",
+      parentSessionID: "ses-main",
+      parentMessageID: "msg-main",
+      parentAgent: "sisyphus",
+    })
+
+    //#when
+    const sent = await executeJsonTool(
+      tools,
+      "send_message",
+      {
+        team_name: "core",
+        type: "message",
+        recipient: "worker_1",
+        summary: "sync",
+        content: "Please update status.",
+      },
+      context,
+    ) as { success: boolean }
+
+    //#then
+    expect(sent.success).toBe(true)
+    expect(resumeCalls).toHaveLength(1)
+    expect(resumeCalls[0].sessionId).toBe("ses-worker-1")
+
+    //#given
+    const createdTask = await executeJsonTool(
+      tools,
+      "team_task_create",
+      {
+        team_name: "core",
+        subject: "Follow-up",
+        description: "Collect teammate update",
+      },
+      context,
+    ) as { id: string }
+    await executeJsonTool(
+      tools,
+      "team_task_update",
+      {
+        team_name: "core",
+        task_id: createdTask.id,
+        owner: "worker_1",
+        status: "in_progress",
+      },
+      context,
+    )
+
+    //#when
+    const killed = await executeJsonTool(
+      tools,
+      "force_kill_teammate",
+      {
+        team_name: "core",
+        agent_name: "worker_1",
+      },
+      context,
+    ) as { success: boolean }
+
+    //#then
+    expect(killed.success).toBe(true)
+    expect(cancelCalls).toHaveLength(1)
+    expect(cancelCalls[0].taskId).toBe("bg-1")
+    expect(cancelCalls[0].options).toEqual(
+      expect.objectContaining({
+        source: "team_force_kill",
+        abortSession: true,
+        skipNotification: true,
+      }),
+    )
+
+    //#when
+    const configAfterKill = await executeJsonTool(tools, "read_config", { team_name: "core" }, context) as {
+      members: Array<{ name: string }>
+    }
+    const taskAfterKill = await executeJsonTool(
+      tools,
+      "team_task_get",
+      {
+        team_name: "core",
+        task_id: createdTask.id,
+      },
+      context,
+    ) as { owner?: string; status: string }
+
+    //#then
+    expect(configAfterKill.members.some((member) => member.name === "worker_1")).toBe(false)
+    expect(taskAfterKill.owner).toBeUndefined()
+    expect(taskAfterKill.status).toBe("pending")
+  })
+})