docs: publish the README screenshot with the demo, and write down the release rule

.github/workflows/demo.yml

@@ -1,7 +1,8 @@
 name: Demo
 
 # Publishes the demo page to GitHub Pages: the CLI collects the made-up scenario in
-# demo/scenario.py, so the page and its report.json match the released code.
+# demo/scenario.py, so the page and its report.json match the released code. The
+# screenshot.png it publishes is the image the README shows.
 on:
   push:
     tags:
@@ -22,7 +23,8 @@ jobs:
       - run: uv python install 3.13
       - run: uv python pin 3.13
       - run: just install
-      - run: just demo
+      - run: uv run --no-sync playwright install --with-deps chromium
+      - run: just demo-screenshot
       - uses: actions/upload-pages-artifact@v5
         with:
           path: site/

AGENTS.md

@@ -22,7 +22,7 @@ Besides the translation checks in `tests/test_page.py`, it has browser smoke tes
 `smoke` and run by `just test-smoke`, not `just test`; still check a page change in a browser against a report from
 the CLI tests, or against `just demo-serve`. `demo/` holds the made-up scenario behind the published demo page: the
 CLI collects it against respx routes, and `.github/workflows/demo.yml` publishes it to GitHub Pages on each release
-tag. A page change that adds a state belongs in the scenario too. Tests
+tag, with the `screenshot.png` the README shows. A page change that adds a state belongs in the scenario too. Tests
 mock GitLab and Jira only with respx routes (pytest-httpx2): the `gitlab` and `jira` fixtures in `tests/conftest.py`
 declare one named static route per call of the scenario in `tests/payloads.py`. A test changes a response by re-mocking a named route; add no fakes, callbacks,
 or stubs.
@@ -39,6 +39,9 @@ description, and PyPI does not rewrite relative links, so a relative one 404s on
 [`skills/release-scope/SKILL.md`](skills/release-scope/SKILL.md) describes the CLI flags, exit codes, and report fields
 for agents, and pins the minor version it describes. Update it, and its version range, in the same change as any of those.
 
+A change to the report schema bumps `SCHEMA_VERSION` and ships in a new minor release; anything else is a patch.
+Move the skill's version range and the README's `release-scope>=X.Y,<X.Z` pins to that minor in the same change.
+
 ## Agent skills
 
 ### Issue tracker

README.md

@@ -25,7 +25,7 @@ copy the release post.
 It writes a static page with a `report.json`, built to run on a schedule and publish with GitLab Pages.
 [Try the demo](https://modern-python.github.io/release-scope/): a made-up shop with four services and six Jira issues.
 
-[![The release-scope page with one Jira issue chosen and the tags it needs picked in two services](https://raw.githubusercontent.com/modern-python/release-scope/main/docs/images/demo.png)](https://modern-python.github.io/release-scope/)
+[![The release-scope page with one Jira issue chosen and the tags it needs picked in two services](https://modern-python.github.io/release-scope/screenshot.png)](https://modern-python.github.io/release-scope/)
 
 ## Quickstart
 

demo/screenshot.py

@@ -0,0 +1,30 @@
+import pathlib
+import sys
+import typing
+
+from playwright.sync_api import FloatRect, Page, ViewportSize, sync_playwright
+
+from demo.server import serve
+
+
+_VIEWPORT: typing.Final = ViewportSize(width=1200, height=760)
+_CLIP: typing.Final = FloatRect(x=0, y=0, width=1200, height=668)
+
+
+def capture(page: Page, url: str, output: pathlib.Path) -> None:
+    page.set_viewport_size(_VIEWPORT)
+    page.goto(f"{url}#issues=SHOP-38")
+    page.locator("details.service .chip:visible").first.wait_for()
+    page.screenshot(path=output, clip=_CLIP)
+
+
+def main(site: pathlib.Path) -> None:
+    with serve(site) as url, sync_playwright() as playwright:
+        browser: typing.Final = playwright.chromium.launch()
+        page: typing.Final = browser.new_page(device_scale_factor=2, color_scheme="light", locale="en-US")
+        capture(page, url, site / "screenshot.png")
+        browser.close()
+
+
+if __name__ == "__main__":
+    main(pathlib.Path(sys.argv[1] if len(sys.argv) > 1 else "site"))

demo/server.py

@@ -0,0 +1,26 @@
+import collections.abc
+import contextlib
+import functools
+import http.server
+import pathlib
+import threading
+import typing
+
+
+class _QuietHandler(http.server.SimpleHTTPRequestHandler):
+    def log_message(self, format: str, *args: typing.Any) -> None:  # noqa: A002, ANN401
+        pass
+
+
+@contextlib.contextmanager
+def serve(directory: pathlib.Path) -> collections.abc.Generator[str, None, None]:
+    server: typing.Final = http.server.ThreadingHTTPServer(
+        ("127.0.0.1", 0), functools.partial(_QuietHandler, directory=str(directory))
+    )
+    thread: typing.Final = threading.Thread(target=server.serve_forever, daemon=True)
+    thread.start()
+    try:
+        yield f"http://127.0.0.1:{server.server_port}/"
+    finally:
+        server.shutdown()
+        server.server_close()

justfile

@@ -47,6 +47,11 @@ test-smoke *args:
 demo:
     uv run --no-sync python -m demo.build site
 
+# Build the demo and save site/screenshot.png, the image the README shows; installs Chromium on first run.
+demo-screenshot: demo
+    uv run --no-sync playwright install chromium
+    uv run --no-sync python -m demo.screenshot site
+
 # Build the demo and serve it at http://127.0.0.1:8000.
 demo-serve: demo
     uv run --no-sync python -m http.server 8000 --bind 127.0.0.1 --directory site

tests/test_browser.py

@@ -1,9 +1,6 @@
 import collections.abc
-import functools
-import http.server
 import pathlib
 import re
-import threading
 import typing
 
 import pytest
@@ -12,6 +9,8 @@
 from typer.testing import CliRunner
 
 from demo.build import build
+from demo.screenshot import capture
+from demo.server import serve
 from release_scope import ioc
 from release_scope.__main__ import MAIN_APP
 from tests.payloads import ENDPOINT, JIRA_ENDPOINT
@@ -20,11 +19,6 @@
 pytestmark = pytest.mark.smoke
 
 
-class _QuietHandler(http.server.SimpleHTTPRequestHandler):
-    def log_message(self, format: str, *args: typing.Any) -> None:  # noqa: A002, ANN401
-        pass
-
-
 @pytest.fixture
 def site(jira: respx.Router, monkeypatch: pytest.MonkeyPatch, tmp_path: pathlib.Path) -> collections.abc.Iterator[str]:
     monkeypatch.setenv("GITLAB_TOKEN", "glpat-test")
@@ -37,25 +31,16 @@ def site(jira: respx.Router, monkeypatch: pytest.MonkeyPatch, tmp_path: pathlib.
         result = CliRunner().invoke(MAIN_APP, ["collect", "-g", "team", "-o", str(output)])
     assert result.exit_code == 0, result.output
     assert jira["jira_search"].called
-    yield from _serve(output)
+    with serve(output) as url:
+        yield url
 
 
 @pytest.fixture
 def demo_site(tmp_path: pathlib.Path) -> collections.abc.Iterator[str]:
     output: typing.Final = tmp_path / "demo"
     build(output)
-    yield from _serve(output)
-
-
-def _serve(directory: pathlib.Path) -> collections.abc.Iterator[str]:
-    server: typing.Final = http.server.ThreadingHTTPServer(
-        ("127.0.0.1", 0), functools.partial(_QuietHandler, directory=str(directory))
-    )
-    thread: typing.Final = threading.Thread(target=server.serve_forever, daemon=True)
-    thread.start()
-    yield f"http://127.0.0.1:{server.server_port}/"
-    server.shutdown()
-    server.server_close()
+    with serve(output) as url:
+        yield url
 
 
 @pytest.fixture
@@ -134,3 +119,15 @@ def test_demo_lists_its_services_and_picks_tags_for_an_issue(page: Page, demo_si
     _issue(page, "SHOP-38").check()
     expect(page).to_have_url(re.compile(r"#issues=SHOP-38&shop/api=2\.5\.0&shop/web=1\.9\.0$"))
     assert errors == []
+
+
+def test_demo_screenshot_shows_an_issue_with_its_picks(
+    page: Page, demo_site: str, errors: list[str], tmp_path: pathlib.Path
+) -> None:
+    output: typing.Final = tmp_path / "screenshot.png"
+
+    capture(page, demo_site, output)
+
+    assert output.read_bytes().startswith(b"\x89PNG")
+    expect(page.locator("details.service .chip:visible > span")).to_have_text(["2.5.0", "1.9.0"])
+    assert errors == []