diff --git a/src/hooks/directory-readme-injector/finder.ts b/src/hooks/directory-readme-injector/finder.ts
index 70e0ba04d..904ef000c 100644
--- a/src/hooks/directory-readme-injector/finder.ts
+++ b/src/hooks/directory-readme-injector/finder.ts
@@ -1,4 +1,4 @@
-import { existsSync } from "node:fs";
+import { access } from "node:fs/promises";
 import { dirname, isAbsolute, join, resolve } from "node:path";
 
 import { README_FILENAME } from "./constants";
@@ -9,17 +9,19 @@ export function resolveFilePath(rootDirectory: string, path: string): string | n
   return resolve(rootDirectory, path);
 }
 
-export function findReadmeMdUp(input: {
+export async function findReadmeMdUp(input: {
   startDir: string;
   rootDir: string;
-}): string[] {
+}): Promise<string[]> {
   const found: string[] = [];
   let current = input.startDir;
 
   while (true) {
     const readmePath = join(current, README_FILENAME);
-    if (existsSync(readmePath)) {
+    try {
+      await access(readmePath);
       found.push(readmePath);
+    } catch {
     }
 
     if (current === input.rootDir) break;
diff --git a/src/hooks/directory-readme-injector/injector.test.ts b/src/hooks/directory-readme-injector/injector.test.ts
index 74294fd7c..c8e704121 100644
--- a/src/hooks/directory-readme-injector/injector.test.ts
+++ b/src/hooks/directory-readme-injector/injector.test.ts
@@ -133,6 +133,32 @@ describe("processFilePathForReadmeInjection", () => {
     expect(output.output).toContain("# Components README")
   })
 
+  it("returns a promise and finds README.md files from temp fixtures", async () => {
+    // given
+    const sourceDirectory = join(testRoot, "src")
+    const componentsDirectory = join(sourceDirectory, "components")
+    mkdirSync(componentsDirectory, { recursive: true })
+    writeFileSync(join(testRoot, "README.md"), "# Root README")
+    writeFileSync(join(sourceDirectory, "README.md"), "# Src README")
+    writeFileSync(join(componentsDirectory, "README.md"), "# Components README")
+
+    const { findReadmeMdUp } = await import("./finder")
+
+    // when
+    const promise = findReadmeMdUp({
+      startDir: componentsDirectory,
+      rootDir: testRoot,
+    })
+
+    // then
+    expect(promise).toBeInstanceOf(Promise)
+    await expect(promise).resolves.toEqual([
+      join(testRoot, "README.md"),
+      join(sourceDirectory, "README.md"),
+      join(componentsDirectory, "README.md"),
+    ])
+  })
+
   it("does not re-inject already cached directories", async () => {
     // given
     const sourceDirectory = join(testRoot, "src")
diff --git a/src/hooks/directory-readme-injector/injector.ts b/src/hooks/directory-readme-injector/injector.ts
index bfeae7d44..ce3ff7212 100644
--- a/src/hooks/directory-readme-injector/injector.ts
+++ b/src/hooks/directory-readme-injector/injector.ts
@@ -1,5 +1,5 @@
 import type { PluginInput } from "@opencode-ai/plugin";
-import { readFileSync } from "node:fs";
+import { readFile } from "node:fs/promises";
 import { dirname } from "node:path";
 
 import type { createDynamicTruncator } from "../../shared/dynamic-truncator";
@@ -31,7 +31,7 @@ export async function processFilePathForReadmeInjection(input: {
 
   const dir = dirname(resolved);
   const cache = getSessionCache(input.sessionCaches, input.sessionID);
-  const readmePaths = findReadmeMdUp({ startDir: dir, rootDir: input.ctx.directory });
+   const readmePaths = await findReadmeMdUp({ startDir: dir, rootDir: input.ctx.directory });
 
   let dirty = false;
   for (const readmePath of readmePaths) {
@@ -39,7 +39,7 @@ export async function processFilePathForReadmeInjection(input: {
     if (cache.has(readmeDir)) continue;
 
     try {
-      const content = readFileSync(readmePath, "utf-8");
+      const content = await readFile(readmePath, "utf-8");
       const { result, truncated } = await input.truncator.truncate(
         input.sessionID,
         content,