Add reminder comment

.changes/tool/amend.py

@@ -5,9 +5,10 @@
 from pathlib import Path
 
 from . import REPO_ROOT, Change
-from .github import post_review_comment
+from .github import post_comment, post_review_comment
 
 DEFAULT_REPO = "smithy-lang/smithy"
+GITHUB_URL = os.environ.get("GITHUB_SERVER_URL", "https://github.com")
 
 
 def amend(
@@ -32,9 +33,31 @@ def amend(
         pr_number = pr_number.split("/")[0]
 
     repository = repository or os.environ.get("GITHUB_REPOSITORY", DEFAULT_REPO)
-    pr_ref = get_pr_ref(pr_number=pr_number, repository=repository)
+    pr_ref = f"[#{pr_number}]({GITHUB_URL}/{repository}/pull/{pr_number})"
 
-    for change_file, change in get_new_changes(base).items():
+    changes = get_new_changes(base)
+    if review_comment:
+        print("No changelog found, adding reminder comment.")
+        description = os.environ.get("PR_TITLE", "Example description").replace(
+            '"', '\\"'
+        )
+        comment = (
+            "This pull request does not contain a staged changelog entry. To create "
+            "one, use the `./.changes/new-change` command. For example:\n\n"
+            f"```\n./.changes/new-change --pull-requests #{pr_number} --type feature "
+            f'--description "{description}"\n```\n\n'
+            "Make sure that the description is appropriate for a changelog entry and "
+            "that the proper feature type is used. See [`./.changes/README`]("
+            f"{GITHUB_URL}/{repository}/tree/main/.changes/README) or run "
+            "`./.changes/new-change -h` for more information."
+        )
+        post_comment(
+            repository=repository,
+            pr_number=pr_number,
+            comment=comment,
+        )
+
+    for change_file, change in changes.items():
         if not change.pull_requests:
             print(f"Amending changelog entry without associated prs: {change_file}")
             change.pull_requests = [pr_ref]
@@ -60,11 +83,6 @@ def amend(
                 change.write(change_file)
 
 
-def get_pr_ref(pr_number: str | None, repository: str):
-    base_url = os.environ.get("GITHUB_SERVER_URL", "https://github.com")
-    return f"[#{pr_number}]({base_url}/{repository}/pull/{pr_number})"
-
-
 def get_new_changes(base: str | None) -> dict[Path, Change]:
     base = base or os.environ.get("GITHUB_BASE_REF", "main")
     print(f"Running a diff against base branch: {base}")

.changes/tool/github.py

@@ -87,18 +87,20 @@ class User(TypedDict):
     login: Required[str]
 
 
-class ReviewComment(TypedDict):
+class Comment(TypedDict):
     user: Required[User]
-    path: Required[str]
     body: str
 
 
+class ReviewComment(Comment):
+    path: Required[str]
+
+
 # https://docs.github.com/en/rest/pulls/comments?apiVersion=2022-11-28#list-review-comments-on-a-pull-request
 def get_review_comments(
     repository: str,
     pr_number: str,
 ) -> Generator[ReviewComment]:
-    _assert_token()
     url = f"{GITHUB_API_URL}/repos/{repository}/pulls/{pr_number}/comments?per_page=100"
     for response in _paginate(url):
         if not isinstance(response.body, list):
@@ -109,6 +111,42 @@ def get_review_comments(
             yield comment  # type: ignore
 
 
+# https://docs.github.com/en/rest/issues/comments?apiVersion=2022-11-28#create-an-issue-comment
+def post_comment(
+    repository: str,
+    pr_number: str,
+    comment: str,
+    allow_duplicate: bool = False,
+) -> None:
+    if not allow_duplicate:
+        for existing_comment in get_review_comments(repository, pr_number):
+            if existing_comment["body"] == comment:
+                print("Review comment already posted, skipping duplicate.")
+                return
+
+    _request(
+        url=f"{GITHUB_API_URL}/repos/{repository}/issues/{pr_number}/comments",
+        body={"body": comment},
+    )
+
+
+# https://docs.github.com/en/rest/issues/comments?apiVersion=2022-11-28#list-issue-comments
+def get_comments(
+    repository: str,
+    pr_number: str,
+) -> Generator[Comment]:
+    url = (
+        f"{GITHUB_API_URL}/repos/{repository}/issues/{pr_number}/comments?per_page=100"
+    )
+    for response in _paginate(url):
+        if not isinstance(response.body, list):
+            raise ValueError(
+                f"Expected list body, but found {type(response.body)}: {response.body}"
+            )
+        for comment in response.body:
+            yield comment  # type: ignore
+
+
 @dataclass
 class JSONResponse:
     headers: dict[str, str]
@@ -125,7 +163,11 @@ def from_http_response(cls, http_response: HTTPResponse) -> Self:
 
 
 def _request(url: str, body: JSON = None) -> JSONResponse:
-    _assert_token()
+    if not GITHUB_TOKEN:
+        raise ValueError(
+            "The GITHUB_TOKEN environment variable must be set to post review comments."
+        )
+
     headers = {
         "Accept": "application/vnd.github+json",
         "Authorization": f"Bearer {GITHUB_TOKEN}",
@@ -173,10 +215,3 @@ def __init__(self, response: HTTPError) -> None:
             json.loads(response.read().decode("utf-8")), indent=2
         )
         super().__init__(f"GitHub API request failed:\n\n{formatted_body}")
-
-
-def _assert_token():
-    if not GITHUB_TOKEN:
-        raise ValueError(
-            "The GITHUB_TOKEN environment variable must be set to post review comments."
-        )

.github/workflows/amend-new-changelogs.yml

@@ -21,6 +21,7 @@ jobs:
               env:
                 GITHUB_TOKEN: ${{ github.token }}
                 TARGET_SHA: ${{ github.event.pull_request.head.sha }}
+                PR_TITLE: ${{ github.event.pull_request.title }}
               run: |
                 git fetch origin ${{ github.base_ref }}
                 ./.changes/amend --review-comment