diff --git a/src/shared/project-discovery-dirs.test.ts b/src/shared/project-discovery-dirs.test.ts
index 39ba5dc13..d2904bc72 100644
--- a/src/shared/project-discovery-dirs.test.ts
+++ b/src/shared/project-discovery-dirs.test.ts
@@ -1,15 +1,10 @@
-import { afterEach, beforeEach, describe, expect, it } from "bun:test"
+import { afterEach, beforeEach, describe, expect, it, mock } from "bun:test"
 import { mkdirSync, realpathSync, rmSync } from "node:fs"
 import { tmpdir } from "node:os"
 import { join } from "node:path"
-import {
-  findProjectAgentsSkillDirs,
-  findProjectClaudeSkillDirs,
-  findProjectOpencodeCommandDirs,
-  findProjectOpencodeSkillDirs,
-} from "./project-discovery-dirs"
 
 const TEST_DIR = join(tmpdir(), `project-discovery-dirs-${Date.now()}`)
+let worktreeSpawnCount = 0
 
 function canonicalPath(path: string): string {
   return realpathSync(path)
@@ -24,7 +19,35 @@ describe("project-discovery-dirs", () => {
     rmSync(TEST_DIR, { recursive: true, force: true })
   })
 
-  it("#given nested .opencode skill directories #when finding project opencode skill dirs #then returns nearest-first with aliases", () => {
+  it("#given repeated worktree detection #when detecting twice #then reuses the cached result", async () => {
+    // given
+    worktreeSpawnCount = 0
+
+    mock.module("node:child_process", () => ({
+      execFileSync: () => {
+        worktreeSpawnCount += 1
+        return TEST_DIR
+      },
+    }))
+
+    const { clearWorktreeCache, detectWorktreePath } = await import("./project-discovery-dirs")
+
+    clearWorktreeCache()
+
+    // when
+    const firstPath = detectWorktreePath("/some/dir")
+    const secondPath = detectWorktreePath("/some/dir")
+    clearWorktreeCache()
+    const thirdPath = detectWorktreePath("/some/dir")
+
+    // then
+    expect(firstPath).toBe(TEST_DIR)
+    expect(secondPath).toBe(TEST_DIR)
+    expect(thirdPath).toBe(TEST_DIR)
+    expect(worktreeSpawnCount).toBe(2)
+  })
+
+  it("#given nested .opencode skill directories #when finding project opencode skill dirs #then returns nearest-first with aliases", async () => {
     // given
     const projectDir = join(TEST_DIR, "project")
     const childDir = join(projectDir, "apps", "cli")
@@ -32,6 +55,8 @@ describe("project-discovery-dirs", () => {
     mkdirSync(join(projectDir, ".opencode", "skills"), { recursive: true })
     mkdirSync(join(TEST_DIR, ".opencode", "skills"), { recursive: true })
 
+    const { findProjectOpencodeSkillDirs } = await import("./project-discovery-dirs")
+
     // when
     const directories = findProjectOpencodeSkillDirs(childDir)
 
@@ -43,13 +68,15 @@ describe("project-discovery-dirs", () => {
     ])
   })
 
-  it("#given nested .opencode command directories #when finding project opencode command dirs #then returns nearest-first with aliases", () => {
+  it("#given nested .opencode command directories #when finding project opencode command dirs #then returns nearest-first with aliases", async () => {
     // given
     const projectDir = join(TEST_DIR, "project")
     const childDir = join(projectDir, "packages", "tool")
     mkdirSync(join(projectDir, ".opencode", "commands"), { recursive: true })
     mkdirSync(join(TEST_DIR, ".opencode", "command"), { recursive: true })
 
+    const { findProjectOpencodeCommandDirs } = await import("./project-discovery-dirs")
+
     // when
     const directories = findProjectOpencodeCommandDirs(childDir)
 
@@ -60,13 +87,15 @@ describe("project-discovery-dirs", () => {
     ])
   })
 
-  it("#given ancestor claude and agents skill directories #when finding project compatibility dirs #then discovers both scopes", () => {
+  it("#given ancestor claude and agents skill directories #when finding project compatibility dirs #then discovers both scopes", async () => {
     // given
     const projectDir = join(TEST_DIR, "project")
     const childDir = join(projectDir, "src", "nested")
     mkdirSync(join(projectDir, ".claude", "skills"), { recursive: true })
     mkdirSync(join(TEST_DIR, ".agents", "skills"), { recursive: true })
 
+    const { findProjectAgentsSkillDirs, findProjectClaudeSkillDirs } = await import("./project-discovery-dirs")
+
     // when
     const claudeDirectories = findProjectClaudeSkillDirs(childDir)
     const agentsDirectories = findProjectAgentsSkillDirs(childDir)
@@ -76,17 +105,20 @@ describe("project-discovery-dirs", () => {
     expect(agentsDirectories).toEqual([canonicalPath(join(TEST_DIR, ".agents", "skills"))])
   })
 
-  it("#given a stop directory #when finding ancestor dirs #then it does not scan beyond the stop boundary", () => {
+  it("#given a stop directory #when finding ancestor dirs #then it does not scan beyond the stop boundary", async () => {
     // given
     const projectDir = join(TEST_DIR, "project")
     const childDir = join(projectDir, "apps", "cli")
     mkdirSync(join(projectDir, ".opencode", "skills"), { recursive: true })
     mkdirSync(join(TEST_DIR, ".opencode", "skills"), { recursive: true })
 
+    const { findProjectOpencodeSkillDirs } = await import("./project-discovery-dirs")
+
     // when
     const directories = findProjectOpencodeSkillDirs(childDir, projectDir)
 
     // then
     expect(directories).toEqual([canonicalPath(join(projectDir, ".opencode", "skills"))])
   })
+
 })
diff --git a/src/shared/project-discovery-dirs.ts b/src/shared/project-discovery-dirs.ts
index 4e22b66f6..5e243df5a 100644
--- a/src/shared/project-discovery-dirs.ts
+++ b/src/shared/project-discovery-dirs.ts
@@ -2,6 +2,8 @@ import { execFileSync } from "node:child_process"
 import { existsSync, realpathSync } from "node:fs"
 import { dirname, join, resolve } from "node:path"
 
+const worktreePathCache = new Map<string, string | undefined>()
+
 function normalizePath(path: string): string {
   const resolvedPath = resolve(path)
   if (!existsSync(resolvedPath)) {
@@ -49,15 +51,28 @@ function findAncestorDirectories(
   }
 }
 
-function detectWorktreePath(directory: string): string | undefined {
+export function clearWorktreeCache(): void {
+  worktreePathCache.clear()
+}
+
+export function detectWorktreePath(directory: string): string | undefined {
+  const resolvedDirectory = resolve(directory)
+  if (worktreePathCache.has(resolvedDirectory)) {
+    return worktreePathCache.get(resolvedDirectory)
+  }
+
   try {
-    return execFileSync("git", ["rev-parse", "--show-toplevel"], {
-      cwd: directory,
+    const worktreePath = execFileSync("git", ["rev-parse", "--show-toplevel"], {
+      cwd: resolvedDirectory,
       encoding: "utf-8",
       timeout: 5000,
       stdio: ["pipe", "pipe", "pipe"],
     }).trim()
+
+    worktreePathCache.set(resolvedDirectory, worktreePath)
+    return worktreePath
   } catch {
+    worktreePathCache.set(resolvedDirectory, undefined)
     return undefined
   }
 }