diff --git a/packages/opencode/src/tool/external-directory.ts b/packages/opencode/src/tool/external-directory.ts
index 1d3958fc464..74c1fe67904 100644
--- a/packages/opencode/src/tool/external-directory.ts
+++ b/packages/opencode/src/tool/external-directory.ts
@@ -18,7 +18,8 @@ export async function assertExternalDirectory(ctx: Tool.Context, target?: string
 
   const kind = options?.kind ?? "file"
   const parentDir = kind === "directory" ? target : path.dirname(target)
-  const glob = path.join(parentDir, "*")
+  const relativeParentDir = path.relative(Instance.directory, parentDir)
+  const glob = path.join(relativeParentDir, "*")
 
   await ctx.ask({
     permission: "external_directory",
@@ -26,7 +27,7 @@ export async function assertExternalDirectory(ctx: Tool.Context, target?: string
     always: [glob],
     metadata: {
       filepath: target,
-      parentDir,
+      parentDir: relativeParentDir,
     },
   })
 }
diff --git a/packages/opencode/test/tool/external-directory.test.ts b/packages/opencode/test/tool/external-directory.test.ts
index b21f6a9715c..0e87bf54ea4 100644
--- a/packages/opencode/test/tool/external-directory.test.ts
+++ b/packages/opencode/test/tool/external-directory.test.ts
@@ -64,7 +64,7 @@ describe("tool.assertExternalDirectory", () => {
 
     const directory = "/tmp/project"
     const target = "/tmp/outside/file.txt"
-    const expected = path.join(path.dirname(target), "*")
+    const expected = path.join(path.relative(directory, path.dirname(target)), "*")
 
     await Instance.provide({
       directory,
@@ -90,7 +90,7 @@ describe("tool.assertExternalDirectory", () => {
 
     const directory = "/tmp/project"
     const target = "/tmp/outside"
-    const expected = path.join(target, "*")
+    const expected = path.join(path.relative(directory, target), "*")
 
     await Instance.provide({
       directory,
diff --git a/packages/opencode/test/tool/read.test.ts b/packages/opencode/test/tool/read.test.ts
index 04ffc80ea67..59626bf6199 100644
--- a/packages/opencode/test/tool/read.test.ts
+++ b/packages/opencode/test/tool/read.test.ts
@@ -72,7 +72,8 @@ describe("tool.read external_directory permission", () => {
         await read.execute({ filePath: path.join(outerTmp.path, "secret.txt") }, testCtx)
         const extDirReq = requests.find((r) => r.permission === "external_directory")
         expect(extDirReq).toBeDefined()
-        expect(extDirReq!.patterns.some((p) => p.includes(outerTmp.path))).toBe(true)
+        // Pattern should be a relative path like "../tmpXXX/*"
+        expect(extDirReq!.patterns.some((p) => p.startsWith("..") && p.endsWith("*"))).toBe(true)
       },
     })
   })