feat: auto-collapse old roadmap comments when posting new ones

Implements GitHub issue #5. When using --post, previous roadmap comments
are automatically minimized (collapsed) using GitHub's GraphQL API before
posting the new roadmap. This keeps PR conversations clean.

Changes:
- Add minimize_old_roadmap_comments() to GitHubClient
- Call minimize before posting in main.py
- Extract ROADMAP_HEADER_PREFIX constant for comment identification
- Add 6 tests for the new functionality

Behavior:
- All comments starting with the roadmap header are collapsed
- Comments from any user are collapsed (not just bots)
- Minimize failures are non-blocking (warnings shown, posting continues)
- Uses OUTDATED classifier for collapsed comments

Author: jwm4

review_roadmap/github/client.py

@@ -5,7 +5,7 @@
 generate review roadmaps.
 """
 
-from typing import Any, Dict, List, Optional
+from typing import Any, Dict, List, Optional, Tuple
 
 import httpx
 
@@ -355,6 +355,78 @@ def check_write_access(
             )
         )
 
+    def minimize_old_roadmap_comments(
+        self, owner: str, repo: str, pr_number: int, header_prefix: str
+    ) -> Tuple[int, int]:
+        """Minimize (collapse) old roadmap comments on a PR.
+
+        Finds all issue comments that start with the given header prefix
+        and minimizes them using GitHub's GraphQL API. This keeps the PR
+        conversation clean by collapsing outdated roadmaps.
+
+        Args:
+            owner: Repository owner.
+            repo: Repository name.
+            pr_number: Pull request number.
+            header_prefix: The prefix to match against comment bodies
+                (e.g., "🗺️ **Auto-Generated Review Roadmap**").
+
+        Returns:
+            Tuple of (minimized_count, error_count).
+        """
+        # Fetch all issue comments (includes node_id needed for GraphQL)
+        resp = self.client.get(f"/repos/{owner}/{repo}/issues/{pr_number}/comments")
+        if resp.status_code != 200:
+            return (0, 0)
+
+        comments = resp.json()
+
+        # Filter for roadmap comments by body prefix
+        roadmap_node_ids = [
+            c["node_id"]
+            for c in comments
+            if c.get("body", "").startswith(header_prefix)
+        ]
+
+        if not roadmap_node_ids:
+            return (0, 0)
+
+        # Minimize each comment using GraphQL
+        minimized = 0
+        errors = 0
+        mutation = """
+            mutation($id: ID!) {
+                minimizeComment(input: {subjectId: $id, classifier: OUTDATED}) {
+                    minimizedComment { isMinimized }
+                }
+            }
+        """
+
+        for node_id in roadmap_node_ids:
+            try:
+                gql_resp = self.client.post(
+                    "https://api.github.com/graphql",
+                    json={"query": mutation, "variables": {"id": node_id}},
+                )
+                if gql_resp.status_code == 200:
+                    data = gql_resp.json()
+                    if data.get("data", {}).get("minimizeComment", {}).get(
+                        "minimizedComment", {}
+                    ).get("isMinimized"):
+                        minimized += 1
+                    elif "errors" in data:
+                        errors += 1
+                    else:
+                        # Response OK but isMinimized not true - count as success
+                        # (might already be minimized)
+                        minimized += 1
+                else:
+                    errors += 1
+            except Exception:
+                errors += 1
+
+        return (minimized, errors)
+
     def post_pr_comment(self, owner: str, repo: str, pr_number: int, body: str) -> Dict[str, Any]:
         """Post a comment on a pull request.
 

review_roadmap/main.py

@@ -10,6 +10,9 @@
 app = typer.Typer(add_completion=False)
 console = Console()
 
+# Header prefix used to identify roadmap comments for collapse feature
+ROADMAP_HEADER_PREFIX = "🗺️ **Auto-Generated Review Roadmap**"
+
 # Initialize structured logging
 configure_logging(
     log_level=settings.REVIEW_ROADMAP_LOG_LEVEL,
@@ -22,7 +25,7 @@ def format_pr_comment(roadmap_content: str) -> str:
     provider = settings.REVIEW_ROADMAP_LLM_PROVIDER
     model = settings.REVIEW_ROADMAP_MODEL_NAME
 
-    header = f"""🗺️ **Auto-Generated Review Roadmap**
+    header = f"""{ROADMAP_HEADER_PREFIX}
 
 > This roadmap was automatically generated by [review-roadmap](https://github.com/ambient-code/review-roadmap).
 > Model: `{provider}/{model}`
@@ -114,6 +117,20 @@ def generate(
 
     if post:
         console.print("[bold blue]Posting roadmap to PR...[/bold blue]")
+        
+        # First, minimize any old roadmap comments (non-fatal if this fails)
+        try:
+            minimized, errors = gh_client.minimize_old_roadmap_comments(
+                owner, repo, pr_number, ROADMAP_HEADER_PREFIX
+            )
+            if minimized > 0:
+                console.print(f"[dim]Collapsed {minimized} previous roadmap(s)[/dim]")
+            if errors > 0:
+                console.print(f"[yellow]Warning: Failed to collapse {errors} comment(s)[/yellow]")
+        except Exception as e:
+            console.print(f"[yellow]Warning: Could not collapse old comments: {e}[/yellow]")
+        
+        # Then post the new comment
         try:
             comment_body = format_pr_comment(roadmap_content)
             gh_client.post_pr_comment(owner, repo, pr_number, comment_body)

tests/test_github_client.py

@@ -436,3 +436,190 @@ def test_post_pr_comment_success():
 
     assert result["id"] == 123456
     assert result["body"] == comment_body
+
+
+# --- Tests for minimize_old_roadmap_comments ---
+
+ROADMAP_PREFIX = "🗺️ **Auto-Generated Review Roadmap**"
+
+
+@respx.mock
+def test_minimize_old_roadmap_comments_no_comments():
+    """Returns (0, 0) when there are no comments on the PR."""
+    owner = "owner"
+    repo = "repo"
+    pr_number = 42
+    
+    url = f"https://api.github.com/repos/{owner}/{repo}/issues/{pr_number}/comments"
+    respx.get(url).mock(return_value=Response(200, json=[]))
+    
+    client = GitHubClient(token="fake-token")
+    minimized, errors = client.minimize_old_roadmap_comments(owner, repo, pr_number, ROADMAP_PREFIX)
+    
+    assert minimized == 0
+    assert errors == 0
+
+
+@respx.mock
+def test_minimize_old_roadmap_comments_no_matching_comments():
+    """Returns (0, 0) when no comments match the roadmap prefix."""
+    owner = "owner"
+    repo = "repo"
+    pr_number = 42
+    
+    url = f"https://api.github.com/repos/{owner}/{repo}/issues/{pr_number}/comments"
+    respx.get(url).mock(return_value=Response(200, json=[
+        {
+            "id": 1,
+            "node_id": "IC_node1",
+            "body": "This is a regular comment",
+            "user": {"login": "user1"},
+            "created_at": "2024-01-01T00:00:00Z"
+        },
+        {
+            "id": 2,
+            "node_id": "IC_node2",
+            "body": "Another comment mentioning roadmap but not starting with prefix",
+            "user": {"login": "user2"},
+            "created_at": "2024-01-02T00:00:00Z"
+        }
+    ]))
+    
+    client = GitHubClient(token="fake-token")
+    minimized, errors = client.minimize_old_roadmap_comments(owner, repo, pr_number, ROADMAP_PREFIX)
+    
+    assert minimized == 0
+    assert errors == 0
+
+
+@respx.mock
+def test_minimize_old_roadmap_comments_success():
+    """Successfully minimizes roadmap comments and ignores non-roadmap comments."""
+    owner = "owner"
+    repo = "repo"
+    pr_number = 42
+    
+    comments_url = f"https://api.github.com/repos/{owner}/{repo}/issues/{pr_number}/comments"
+    graphql_url = "https://api.github.com/graphql"
+    
+    # Mix of roadmap and non-roadmap comments
+    respx.get(comments_url).mock(return_value=Response(200, json=[
+        {
+            "id": 1,
+            "node_id": "IC_roadmap1",
+            "body": f"{ROADMAP_PREFIX}\n\nOld roadmap content here",
+            "user": {"login": "github-actions[bot]"},
+            "created_at": "2024-01-01T00:00:00Z"
+        },
+        {
+            "id": 2,
+            "node_id": "IC_regular",
+            "body": "Regular comment - should not be minimized",
+            "user": {"login": "reviewer"},
+            "created_at": "2024-01-02T00:00:00Z"
+        },
+        {
+            "id": 3,
+            "node_id": "IC_roadmap2",
+            "body": f"{ROADMAP_PREFIX}\n\nAnother old roadmap",
+            "user": {"login": "user1"},
+            "created_at": "2024-01-03T00:00:00Z"
+        }
+    ]))
+    
+    # Mock GraphQL responses for both roadmap comments
+    respx.post(graphql_url).mock(return_value=Response(200, json={
+        "data": {
+            "minimizeComment": {
+                "minimizedComment": {"isMinimized": True}
+            }
+        }
+    }))
+    
+    client = GitHubClient(token="fake-token")
+    minimized, errors = client.minimize_old_roadmap_comments(owner, repo, pr_number, ROADMAP_PREFIX)
+    
+    # Should minimize 2 roadmap comments, not the regular one
+    assert minimized == 2
+    assert errors == 0
+
+
+@respx.mock
+def test_minimize_old_roadmap_comments_graphql_error():
+    """Handles GraphQL errors gracefully and counts them."""
+    owner = "owner"
+    repo = "repo"
+    pr_number = 42
+    
+    comments_url = f"https://api.github.com/repos/{owner}/{repo}/issues/{pr_number}/comments"
+    graphql_url = "https://api.github.com/graphql"
+    
+    respx.get(comments_url).mock(return_value=Response(200, json=[
+        {
+            "id": 1,
+            "node_id": "IC_roadmap1",
+            "body": f"{ROADMAP_PREFIX}\n\nOld roadmap",
+            "user": {"login": "user1"},
+            "created_at": "2024-01-01T00:00:00Z"
+        }
+    ]))
+    
+    # Mock GraphQL error response
+    respx.post(graphql_url).mock(return_value=Response(200, json={
+        "errors": [{"message": "Could not resolve to a node with the global id"}]
+    }))
+    
+    client = GitHubClient(token="fake-token")
+    minimized, errors = client.minimize_old_roadmap_comments(owner, repo, pr_number, ROADMAP_PREFIX)
+    
+    assert minimized == 0
+    assert errors == 1
+
+
+@respx.mock
+def test_minimize_old_roadmap_comments_http_error():
+    """Handles HTTP errors on GraphQL endpoint gracefully."""
+    owner = "owner"
+    repo = "repo"
+    pr_number = 42
+    
+    comments_url = f"https://api.github.com/repos/{owner}/{repo}/issues/{pr_number}/comments"
+    graphql_url = "https://api.github.com/graphql"
+    
+    respx.get(comments_url).mock(return_value=Response(200, json=[
+        {
+            "id": 1,
+            "node_id": "IC_roadmap1",
+            "body": f"{ROADMAP_PREFIX}\n\nOld roadmap",
+            "user": {"login": "user1"},
+            "created_at": "2024-01-01T00:00:00Z"
+        }
+    ]))
+    
+    # Mock HTTP 403 error on GraphQL
+    respx.post(graphql_url).mock(return_value=Response(403, json={
+        "message": "Forbidden"
+    }))
+    
+    client = GitHubClient(token="fake-token")
+    minimized, errors = client.minimize_old_roadmap_comments(owner, repo, pr_number, ROADMAP_PREFIX)
+    
+    assert minimized == 0
+    assert errors == 1
+
+
+@respx.mock
+def test_minimize_old_roadmap_comments_fetch_error():
+    """Returns (0, 0) when fetching comments fails."""
+    owner = "owner"
+    repo = "repo"
+    pr_number = 42
+    
+    comments_url = f"https://api.github.com/repos/{owner}/{repo}/issues/{pr_number}/comments"
+    respx.get(comments_url).mock(return_value=Response(404, json={"message": "Not Found"}))
+    
+    client = GitHubClient(token="fake-token")
+    minimized, errors = client.minimize_old_roadmap_comments(owner, repo, pr_number, ROADMAP_PREFIX)
+    
+    assert minimized == 0
+    assert errors == 0