fix(git): handle empty repositories without raw HEAD errors

packages/cli/test/snapshot.test.ts

@@ -77,13 +77,17 @@ describe("codedecay snapshot CLI contract", () => {
     expect(comparison.stdout).toBe("");
   });
 
-  it("returns a clean error for git repositories with no commits", async () => {
+  it("emits a clean snapshot for git repositories with no commits", async () => {
     const repo = createTempDir();
     git(repo, ["init", "-b", "main"]);
+    writeFile(repo, "src/app.ts", "export const value = 1;\n");
 
     const result = await run(["snapshot", "--format", "json"], repo);
-    expect(result.exitCode).toBe(2);
-    expect(result.stderr).toContain("Git command failed");
-    expect(result.stdout).toBe("");
+    const snapshot = JSON.parse(result.stdout);
+
+    expect(result.exitCode).toBe(0);
+    expect(result.stderr).toBe("");
+    expect(snapshot.tool).toBe("CodeDecay");
+    expect(snapshot.summary.changedFiles).toBe(1);
   });
 });

packages/git/src/changed-files.ts

@@ -1,10 +1,17 @@
+import { readFileSync } from "node:fs";
+import { join } from "node:path";
 import type { FileChange } from "@submuxhq/codedecay-core";
 import { runGit } from "./command";
 import { parseAddedLines, parseNameStatus, parseNumStat } from "./parsers";
+import { getRepoRoot } from "./repository";
 import type { GitDiffOptions } from "./types";
 import { getUntrackedFiles } from "./untracked";
 
 export function getGitChangedFiles(options: GitDiffOptions): FileChange[] {
+  if (!options.base && !options.head && !hasHeadCommit(options.cwd)) {
+    return getNoCommitChanges(options.cwd);
+  }
+
   const rangeArgs = getDiffRangeArgs(options);
   const nameStatusOutput = runGit(options.cwd, [
     "diff",
@@ -64,3 +71,56 @@ function getDiffRangeArgs(options: GitDiffOptions): string[] {
 
   return ["HEAD"];
 }
+
+function hasHeadCommit(cwd: string): boolean {
+  try {
+    runGit(cwd, ["rev-parse", "--verify", "--quiet", "HEAD"]);
+    return true;
+  } catch {
+    return false;
+  }
+}
+
+function getNoCommitChanges(cwd: string): FileChange[] {
+  const output = runGit(cwd, ["ls-files", "--cached", "--others", "--exclude-standard", "--full-name"]);
+  if (!output.trim()) {
+    return [];
+  }
+
+  const repoRoot = getRepoRoot(cwd);
+  const seen = new Set<string>();
+  return output
+    .split(/\r?\n/)
+    .filter(Boolean)
+    .filter((path) => {
+      if (seen.has(path)) {
+        return false;
+      }
+      seen.add(path);
+      return true;
+    })
+    .map((path) => createAddedChange(repoRoot, path));
+}
+
+function createAddedChange(repoRoot: string, path: string): FileChange {
+  const lines = readTextFile(join(repoRoot, path))
+    .split(/\r?\n/)
+    .map((line, index) => ({ line: index + 1, content: line }))
+    .filter((line) => line.content.length > 0);
+
+  return {
+    path,
+    status: "added",
+    additions: lines.length,
+    deletions: 0,
+    addedLines: lines
+  };
+}
+
+function readTextFile(path: string): string {
+  try {
+    return readFileSync(path, "utf8");
+  } catch {
+    return "";
+  }
+}

packages/git/test/git.test.ts

@@ -121,6 +121,22 @@ describe("live git integration", () => {
     ]);
   });
 
+  it("handles repositories with no commits without leaking raw HEAD errors", () => {
+    const repo = createEmptyRepo();
+    writeFile(repo, "src/app.ts", "export const value = 1;\n");
+
+    expect(() => getGitChangedFiles({ cwd: repo })).not.toThrow(/ambiguous argument 'HEAD'/);
+    expect(getGitChangedFiles({ cwd: repo })).toEqual([
+      {
+        path: "src/app.ts",
+        status: "added",
+        additions: 1,
+        deletions: 0,
+        addedLines: [{ line: 1, content: "export const value = 1;" }]
+      }
+    ]);
+  });
+
   it("throws a clear error for invalid refs", () => {
     const repo = createRepo({
       "src/app.ts": "export const value = 1;\n"
@@ -215,6 +231,16 @@ function createRepo(files: Record<string, string>): string {
   return repo;
 }
 
+function createEmptyRepo(): string {
+  const repo = mkdtempSync(join(tmpdir(), "codedecay-git-empty-"));
+  tempRoots.push(repo);
+
+  git(repo, ["init", "-b", "main"]);
+  git(repo, ["config", "user.email", "codedecay@example.com"]);
+  git(repo, ["config", "user.name", "CodeDecay Test"]);
+  return repo;
+}
+
 function writeFile(root: string, path: string, contents: string): void {
   const fullPath = join(root, path);
   mkdirSync(dirname(fullPath), { recursive: true });