feat: save markdown output to a file

README.md

@@ -21,11 +21,7 @@ Writing a PR description after the coding is finished is easy to postpone. diffn
 
 ## Quick start
 
-```bash
-git clone https://github.com/LucasXlab/diffnote.git && cd diffnote
-python3 -m pip install .
-python3 scripts/demo.py
-```
+
 
 ## Features
 
@@ -80,12 +76,6 @@ python3 -m pytest -q
 
 The demo uses a temporary fixture and does not inspect your personal repositories or agent homes.
 
-## Roadmap
-
-- [ ] Improve error messages for invalid refs and empty histories.
-- [ ] Add configurable grouping rules.
-
-## Contributing
 
 Read [CONTRIBUTING.md](CONTRIBUTING.md). Report reproducible problems in [Issues](https://github.com/LucasXlab/diffnote/issues). Follow [SECURITY.md](SECURITY.md) for sensitive reports.
 

src/diffnote/cli.py

@@ -28,6 +28,8 @@ def build_parser():
     fmt = p.add_argument_group("output")
     fmt.add_argument("--markdown", action="store_true",
                      help="Print a GitHub PR-body markdown.")
+    fmt.add_argument("--save", metavar="PATH",
+                     help="Write markdown output to PATH instead of stdout (requires --markdown).")
     fmt.add_argument("--json", action="store_true",
                      help="Print machine-readable JSON.")
     color = fmt.add_mutually_exclusive_group()
@@ -55,7 +57,10 @@ def get_diff(args, cwd):
 
 
 def main(argv=None):
-    args = build_parser().parse_args(argv)
+    parser = build_parser()
+    args = parser.parse_args(argv)
+    if args.save and (not args.markdown or args.json):
+        parser.error("--save requires --markdown and cannot be used with --json")
     try:
         cwd = gitutil.repo_root()
     except gitutil.GitError as exc:
@@ -89,7 +94,16 @@ def main(argv=None):
     if args.json:
         print(render.render_json(summary, llm_prose))
     elif args.markdown:
-        print(render.render_markdown(summary, llm_prose))
+        markdown = render.render_markdown(summary, llm_prose)
+        if args.save:
+            try:
+                with open(args.save, "w", encoding="utf-8", newline="\n") as output_file:
+                    output_file.write(markdown + "\n")
+            except OSError as exc:
+                print(f"diffnote: could not write {args.save}: {exc}", file=sys.stderr)
+                return 1
+        else:
+            print(markdown)
     else:
         print(render.render_terminal(summary, use_color=args.use_color, llm_prose=llm_prose))
     return 0

tests/test_cli.py

@@ -93,6 +93,25 @@ def test_markdown_output(capsys):
     assert "## Changes" in out
 
 
+def test_save_markdown_writes_file_without_stdout(capsys):
+    d = _make_dirty_repo()
+    output_path = os.path.join(d, "pr-body.md")
+    old = os.getcwd()
+    os.chdir(d)
+    try:
+        rc = cli.main(["--save", output_path, "--markdown"])
+    finally:
+        os.chdir(old)
+    captured = capsys.readouterr()
+    with open(output_path, encoding="utf-8") as output_file:
+        saved = output_file.read()
+    assert rc == 0
+    assert captured.out == ""
+    assert "## Summary" in saved
+    assert "## Changes" in saved
+    assert saved.endswith("\n")
+
+
 def test_no_changes(capsys):
     import os
     d = tempfile.mkdtemp()