fix(infra): preserve git metadata across short reads (#109419)

Co-authored-by: Peter Steinberger <steipete@gmail.com>
Co-authored-by: ZengWen-DT <ceng.wen@xydigit.com>

src/infra/git-commit.test.ts

@@ -1,4 +1,5 @@
 // Covers git commit helper behavior in fake repositories.
+import fsSync from "node:fs";
 import fs from "node:fs/promises";
 import path from "node:path";
 import process from "node:process";
@@ -56,6 +57,23 @@ async function makeFakeOpenClawPackage(root: string) {
   await fs.writeFile(path.join(root, "package.json"), JSON.stringify({ name: "openclaw" }));
 }
 
+function limitPositionalReads(maxBytes: number) {
+  const realReadSync = fsSync.readSync.bind(fsSync);
+  let totalBytesRead = 0;
+  vi.spyOn(fsSync, "readSync").mockImplementation(((
+    fd: number,
+    buffer: NodeJS.ArrayBufferView,
+    offset: number,
+    length: number,
+    position: number | null,
+  ) => {
+    const bytesRead = realReadSync(fd, buffer, offset, Math.min(length, maxBytes), position);
+    totalBytesRead += bytesRead;
+    return bytesRead;
+  }) as typeof fsSync.readSync);
+  return () => totalBytesRead;
+}
+
 describe("git commit resolution", () => {
   let resolveCommitHash: (typeof import("./git-commit.js"))["resolveCommitHash"];
 
@@ -210,7 +228,7 @@ describe("git commit resolution", () => {
     expect(resolveCommitHash({ cwd: repoA, env: {} })).toBe("0123456");
   });
 
-  it("reads packed refs from the common git dir for worktree-style checkouts", async () => {
+  it("reads packed refs after short commondir reads in worktree-style checkouts", async () => {
     const temp = await makeTempDir("git-commit-packed-refs");
     const checkoutRoot = path.join(temp, "checkout");
     const commonGitDir = path.join(temp, "git-common");
@@ -224,6 +242,7 @@ describe("git commit resolution", () => {
         "refs/heads/main": "0123456789abcdef0123456789abcdef01234567",
       },
     });
+    limitPositionalReads(4);
 
     expect(resolveCommitHash({ cwd: checkoutRoot, env: {} })).toBe("0123456");
   });
@@ -381,6 +400,57 @@ describe("git commit resolution", () => {
     expect(resolveCommitHash({ cwd: repoRootValue, env: {} })).toBe("bbbbbbb");
   });
 
+  it("fills short positional reads for loose refs", async () => {
+    const temp = await makeTempDir("git-commit-short-ref");
+    const repoRoot = path.join(temp, "repo");
+    await makeFakeGitRepo(repoRoot, {
+      head: "ref: refs/heads/main\n",
+      refs: {
+        "refs/heads/main": "abcdef0123456789abcdef0123456789abcdef01",
+      },
+    });
+    limitPositionalReads(4);
+
+    expect(resolveCommitHash({ cwd: repoRoot, env: {} })).toBe("abcdef0");
+  });
+
+  it("keeps short-read retries within the bounded metadata window", async () => {
+    const temp = await makeTempDir("git-commit-bounded-ref");
+    const repoRoot = path.join(temp, "repo");
+    await makeFakeGitRepo(repoRoot, {
+      head: "ref: refs/heads/main\n",
+      refs: {
+        "refs/heads/main": `${"x".repeat(256)}abcdef0123456789`,
+      },
+    });
+    const totalBytesRead = limitPositionalReads(4);
+
+    expect(resolveCommitHash({ cwd: repoRoot, env: {} })).toBeNull();
+    expect(totalBytesRead()).toBe(256);
+  });
+
+  it("falls back to baked metadata when a bounded Git metadata read errors", async () => {
+    const temp = await makeTempDir("git-commit-read-error");
+    const repoRoot = path.join(temp, "repo");
+    await makeFakeGitRepo(repoRoot, {
+      head: "ref: refs/heads/main\n",
+      refs: {
+        "refs/heads/main": "abcdef0123456789abcdef0123456789abcdef01",
+      },
+    });
+    vi.spyOn(fsSync, "readSync").mockImplementationOnce((() => {
+      throw Object.assign(new Error("EIO: forced read failure"), { code: "EIO" });
+    }) as typeof fsSync.readSync);
+
+    expect(
+      resolveCommitHash({
+        cwd: repoRoot,
+        env: {},
+        readers: { readBuildInfoCommit: () => "deadbee" },
+      }),
+    ).toBe("deadbee");
+  });
+
   it("reads full HEAD refs before parsing long branch names", async () => {
     const temp = await makeTempDir("git-commit-long-head");
     const repoRootLocal = path.join(temp, "repo");

src/infra/git-commit.ts

@@ -4,6 +4,7 @@ import { createRequire } from "node:module";
 import path from "node:path";
 import { fileURLToPath } from "node:url";
 import { normalizeLowercaseStringOrEmpty } from "@openclaw/normalization-core/string-coerce";
+import { readFileWindowFullySync } from "./file-read.js";
 import { resolveGitHeadPath } from "./git-root.js";
 import { pruneMapToMaxSize } from "./map-size.js";
 import { resolveOpenClawPackageRootSync } from "./openclaw-root.js";
@@ -59,7 +60,7 @@ const safeReadFilePrefix = (filePath: string, limit = 256) => {
   const fd = fs.openSync(filePath, "r");
   try {
     const buf = Buffer.alloc(limit);
-    const bytesRead = fs.readSync(fd, buf, 0, limit, 0);
+    const bytesRead = readFileWindowFullySync(fd, buf, 0);
     return buf.subarray(0, bytesRead).toString("utf-8");
   } finally {
     fs.closeSync(fd);