diff --git a/.sisyphus/notepads/team-mode/learnings.md b/.sisyphus/notepads/team-mode/learnings.md
index 5349aca4e..97e13ba01 100644
--- a/.sisyphus/notepads/team-mode/learnings.md
+++ b/.sisyphus/notepads/team-mode/learnings.md
@@ -3,3 +3,8 @@
 - `MemberSchema` needs `.strict()` on the base shape so the discriminatedUnion rejects members that mix `category` and `subagent_type`.
 - `backendType` and `isActive` defaults are part of the schema contract, so tests should use `toMatchObject` instead of exact object equality.
 - The eligibility registry must preserve the plan strings verbatim, especially the hard-reject messages for Momus verification.
+## Task 12 learnings
+
+- `git worktree remove` can leave prunable entries behind, so pruning after removal keeps the repo index tidy.
+- For testability, a tiny git command runner hook made git-unavailable coverage simpler than mocking Bun directly.
+- Detached worktrees need unique temp paths in tests to avoid cross-run collisions.
diff --git a/src/features/team-mode/index.ts b/src/features/team-mode/index.ts
index 51f739d01..6aa6742a6 100644
--- a/src/features/team-mode/index.ts
+++ b/src/features/team-mode/index.ts
@@ -1 +1,2 @@
 export * from "./types"
+export * from "./team-worktree"
diff --git a/src/features/team-mode/team-worktree/cleanup.test.ts b/src/features/team-mode/team-worktree/cleanup.test.ts
new file mode 100644
index 000000000..f47c63af9
--- /dev/null
+++ b/src/features/team-mode/team-worktree/cleanup.test.ts
@@ -0,0 +1,31 @@
+/// <reference types="bun-types" />
+
+import { afterAll, expect, test } from "bun:test"
+import fs from "node:fs/promises"
+import os from "node:os"
+import path from "node:path"
+
+import { findOrphanWorktrees } from "./cleanup"
+
+const temporaryDirectories: string[] = []
+
+afterAll(async () => {
+  for (const directory of temporaryDirectories) {
+    await fs.rm(directory, { recursive: true, force: true })
+  }
+})
+
+test("given runtime mismatch when findOrphanWorktrees then returns orphan paths", async () => {
+  // given
+  const baseDir = await fs.mkdtemp(path.join(os.tmpdir(), "team-worktree-orphans-"))
+  temporaryDirectories.push(baseDir)
+  await fs.mkdir(path.join(baseDir, "worktrees", "t1", "m1"), { recursive: true })
+  await fs.mkdir(path.join(baseDir, "runtime", "t1"), { recursive: true })
+  await fs.writeFile(path.join(baseDir, "runtime", "t1", "state.json"), JSON.stringify({ status: "deleted" }))
+
+  // when
+  const result = await findOrphanWorktrees(baseDir, {})
+
+  // then
+  expect(result).toEqual([path.join(baseDir, "worktrees", "t1", "m1")])
+})
diff --git a/src/features/team-mode/team-worktree/cleanup.ts b/src/features/team-mode/team-worktree/cleanup.ts
new file mode 100644
index 000000000..673ecebc1
--- /dev/null
+++ b/src/features/team-mode/team-worktree/cleanup.ts
@@ -0,0 +1,77 @@
+import fs from "node:fs/promises"
+import path from "node:path"
+
+import type { TeamModeConfig } from "./manager"
+
+async function runGit(args: string[]): Promise<{ code: number; stderr: string }> {
+  const process = Bun.spawn({ cmd: ["git", ...args], stdout: "pipe", stderr: "pipe" })
+  const [exitCode, stderrText] = await Promise.all([process.exited, new Response(process.stderr).text()])
+  return { code: exitCode, stderr: stderrText }
+}
+
+export async function removeWorktree(worktreePath: string): Promise<void> {
+  await fs.rm(worktreePath, { recursive: true, force: true })
+
+  const rootLookup = await Bun.spawn({
+    cmd: ["git", "-C", worktreePath, "rev-parse", "--show-superproject-working-tree"],
+    stdout: "pipe",
+    stderr: "pipe",
+  })
+  const [rootExitCode, rootStdout] = await Promise.all([
+    rootLookup.exited,
+    new Response(rootLookup.stdout).text(),
+    new Response(rootLookup.stderr).text(),
+  ])
+  const result =
+    rootExitCode === 0 && rootStdout.trim().length > 0
+      ? await runGit(["-C", rootStdout.trim(), "worktree", "remove", "--force", worktreePath])
+      : await runGit(["worktree", "remove", "--force", worktreePath])
+
+  if (
+    result.code !== 0 &&
+    !result.stderr.includes("not a worktree") &&
+    !result.stderr.includes("not a working tree") &&
+    !result.stderr.includes("already removed")
+  ) {
+    throw new Error(result.stderr.trim() || "git worktree remove failed")
+  }
+
+  if (rootExitCode === 0 && rootStdout.trim().length > 0) {
+    await runGit(["-C", rootStdout.trim(), "worktree", "prune"])
+  }
+}
+
+export async function findOrphanWorktrees(baseDir: string, _config: TeamModeConfig): Promise<string[]> {
+  const orphanWorktrees: string[] = []
+  const worktreesDir = path.join(baseDir, "worktrees")
+
+  let teamRunDirectories: string[]
+  try {
+    teamRunDirectories = await fs.readdir(worktreesDir)
+  } catch {
+    return orphanWorktrees
+  }
+
+  for (const teamRunId of teamRunDirectories) {
+    const teamRunPath = path.join(worktreesDir, teamRunId)
+    const memberNames = await fs.readdir(teamRunPath).catch(() => [])
+
+    for (const memberName of memberNames) {
+      const worktreePath = path.join(teamRunPath, memberName)
+      const statePath = path.join(baseDir, "runtime", teamRunId, "state.json")
+
+      try {
+        const stateContents = await fs.readFile(statePath, "utf8")
+        const state = JSON.parse(stateContents) as { status?: string }
+
+        if (state.status !== "active" && state.status !== "shutdown_requested") {
+          orphanWorktrees.push(worktreePath)
+        }
+      } catch {
+        orphanWorktrees.push(worktreePath)
+      }
+    }
+  }
+
+  return orphanWorktrees
+}
diff --git a/src/features/team-mode/team-worktree/index.ts b/src/features/team-mode/team-worktree/index.ts
new file mode 100644
index 000000000..e311ff757
--- /dev/null
+++ b/src/features/team-mode/team-worktree/index.ts
@@ -0,0 +1,2 @@
+export { GitUnavailableError, createWorktree, isGitAvailable, validateWorktreeSpec } from "./manager"
+export { findOrphanWorktrees, removeWorktree } from "./cleanup"
diff --git a/src/features/team-mode/team-worktree/manager.test.ts b/src/features/team-mode/team-worktree/manager.test.ts
new file mode 100644
index 000000000..b1e98556b
--- /dev/null
+++ b/src/features/team-mode/team-worktree/manager.test.ts
@@ -0,0 +1,104 @@
+/// <reference types="bun-types" />
+
+import { afterAll, beforeAll, describe, expect, mock, test } from "bun:test"
+import { randomUUID } from "node:crypto"
+import fs from "node:fs/promises"
+import os from "node:os"
+import path from "node:path"
+
+import { GitUnavailableError, createWorktree, setGitCommandRunnerForTests, validateWorktreeSpec } from "./manager"
+import { removeWorktree } from "./cleanup"
+
+const temporaryDirectories: string[] = []
+
+async function initGitRepo(): Promise<string> {
+  const repositoryRoot = await fs.mkdtemp(path.join(os.tmpdir(), "team-worktree-"))
+  temporaryDirectories.push(repositoryRoot)
+  Bun.spawnSync(["git", "init"], { cwd: repositoryRoot, stdout: "pipe", stderr: "pipe" })
+  await fs.writeFile(path.join(repositoryRoot, "README.md"), "hello\n")
+  Bun.spawnSync(["git", "add", "README.md"], { cwd: repositoryRoot, stdout: "pipe", stderr: "pipe" })
+  Bun.spawnSync(["git", "config", "user.email", "test@example.com"], { cwd: repositoryRoot, stdout: "pipe", stderr: "pipe" })
+  Bun.spawnSync(["git", "config", "user.name", "Test User"], { cwd: repositoryRoot, stdout: "pipe", stderr: "pipe" })
+  Bun.spawnSync(["git", "commit", "-m", "init"], { cwd: repositoryRoot, stdout: "pipe", stderr: "pipe" })
+  return repositoryRoot
+}
+
+beforeAll(() => {
+  mock.restore()
+})
+
+afterAll(async () => {
+  for (const directory of temporaryDirectories) {
+    await fs.rm(directory, { recursive: true, force: true })
+  }
+  mock.restore()
+})
+
+describe("team-worktree manager", () => {
+  test("given tmp git repo when createWorktree then registers detached worktree", async () => {
+    // given
+    const repositoryRoot = await initGitRepo()
+    const worktreePath = `../worktree-${randomUUID()}`
+    const worktreeDirectory = path.resolve(repositoryRoot, worktreePath)
+
+    // when
+    const resultPath = await createWorktree(repositoryRoot, "t1", "m1", worktreePath, {})
+
+    // then
+    expect(resultPath).toBe(worktreeDirectory)
+    await expect(fs.stat(worktreeDirectory)).resolves.toBeDefined()
+    const listResult = Bun.spawnSync(["git", "worktree", "list"], { cwd: repositoryRoot, stdout: "pipe", stderr: "pipe" })
+    expect(new TextDecoder().decode(listResult.stdout)).toContain(worktreeDirectory)
+    const headResult = Bun.spawnSync(["git", "-C", worktreeDirectory, "rev-parse", "HEAD"], { stdout: "pipe", stderr: "pipe" })
+    const repoHeadResult = Bun.spawnSync(["git", "-C", repositoryRoot, "rev-parse", "HEAD"], { stdout: "pipe", stderr: "pipe" })
+    expect(new TextDecoder().decode(headResult.stdout).trim()).toBe(new TextDecoder().decode(repoHeadResult.stdout).trim())
+  })
+
+  test("validateWorktreeSpec rejects bare name", () => {
+    // given
+    const worktreePath = "feature-x"
+
+    // when
+    const validate = () => validateWorktreeSpec(worktreePath)
+
+    // then
+    expect(validate).toThrow("worktreePath must be a filesystem path (relative './...', '../...' or absolute '/...')")
+  })
+
+  test("given git unavailable when createWorktree then throws unavailable error", async () => {
+    // given
+    const repositoryRoot = await initGitRepo()
+    setGitCommandRunnerForTests(async (args) => {
+      if (args[0] === "--version") {
+        return { code: 1, stderr: "git missing" }
+      }
+
+      return { code: 0, stderr: "" }
+    })
+
+    // when
+    const create = createWorktree(repositoryRoot, "t1", "m1", `../worktree-${randomUUID()}`, {})
+
+    // then
+    await expect(create).rejects.toBeInstanceOf(GitUnavailableError)
+    setGitCommandRunnerForTests(async (args) => {
+      if (args[0] === "--version") {
+        return { code: 0, stderr: "" }
+      }
+
+      return { code: 0, stderr: "" }
+    })
+  })
+
+  test("given created worktree when removeWorktree then directory disappears", async () => {
+    // given
+    const repositoryRoot = await initGitRepo()
+    const worktreePath = await createWorktree(repositoryRoot, "t1", "m1", `../worktree-${randomUUID()}`, {})
+
+    // when
+    await removeWorktree(worktreePath)
+
+    // then
+    await expect(fs.stat(worktreePath)).rejects.toThrow()
+  })
+})
diff --git a/src/features/team-mode/team-worktree/manager.ts b/src/features/team-mode/team-worktree/manager.ts
new file mode 100644
index 000000000..359df4cd0
--- /dev/null
+++ b/src/features/team-mode/team-worktree/manager.ts
@@ -0,0 +1,62 @@
+import path from "node:path"
+
+export type TeamModeConfig = {
+  worktreeBaseDir?: string
+}
+
+export class GitUnavailableError extends Error {
+  constructor() {
+    super("git required for worktree members")
+    this.name = "GitUnavailableError"
+  }
+}
+
+function countParentSegments(spec: string): number {
+  return spec.split("/").filter((segment) => segment === "..").length
+}
+
+async function runGit(args: string[], cwd?: string): Promise<{ code: number; stderr: string }> {
+  const process = Bun.spawn({ cmd: ["git", ...args], cwd, stdout: "pipe", stderr: "pipe" })
+  const [exitCode, stderrBytes] = await Promise.all([process.exited, new Response(process.stderr).text()])
+  return { code: exitCode, stderr: stderrBytes }
+}
+
+let gitCommandRunner = runGit
+
+export function setGitCommandRunnerForTests(runner: typeof runGit): void {
+  gitCommandRunner = runner
+}
+
+export async function isGitAvailable(): Promise<boolean> {
+  const result = await gitCommandRunner(["--version"])
+  return result.code === 0
+}
+
+export function validateWorktreeSpec(spec: string): void {
+  if (!/^(\.\.?\/|\/).+/.test(spec) || countParentSegments(spec) > 2) {
+    throw new Error("worktreePath must be a filesystem path (relative './...', '../...' or absolute '/...')")
+  }
+}
+
+export async function createWorktree(
+  repoRoot: string,
+  _teamRunId: string,
+  _memberName: string,
+  worktreePath: string,
+  _config: TeamModeConfig,
+): Promise<string> {
+  validateWorktreeSpec(worktreePath)
+
+  if (!(await isGitAvailable())) {
+    throw new GitUnavailableError()
+  }
+
+  const absolutePath = path.isAbsolute(worktreePath) ? worktreePath : path.resolve(repoRoot, worktreePath)
+  const result = await gitCommandRunner(["-C", repoRoot, "worktree", "add", "--detach", absolutePath])
+
+  if (result.code !== 0) {
+    throw new Error(result.stderr.trim() || "git worktree add failed")
+  }
+
+  return absolutePath
+}