diff --git a/.claude/commands/dedupe.md b/.claude/commands/dedupe.md
new file mode 100644
index 000000000..8f05bb4ca
--- /dev/null
+++ b/.claude/commands/dedupe.md
@@ -0,0 +1,37 @@
+---
+allowed-tools: Bash(gh issue view:*), Bash(gh search:*), Bash(gh issue list:*), Bash(gh api:*), Bash(gh issue comment:*), Task
+description: Find duplicate GitHub issues
+---
+
+Find up to 3 likely duplicate issues for a given GitHub issue.
+
+To do this, follow these steps precisely:
+
+1. Use an agent to check if the Github issue (a) is closed, (b) does not need to be deduped (eg. because it is broad product feedback without a specific solution, or positive feedback), or (c) already has a duplicates comment that you made earlier. If so, do not proceed.
+
+2. Use an agent to view a Github issue, and ask the agent to return a summary of the issue
+
+3. Then, launch 5 parallel agents to search Github for duplicates of this issue, using diverse keywords and search approaches, using the summary from #1
+
+4. Next, feed the results from #1 and #2 into another agent, so that it can filter out false positives, that are likely not actually duplicates of the original issue. If there are no duplicates remaining, do not proceed.
+
+5. Finally, comment back on the issue with a list of up to three duplicate issues (or zero, if there are no likely duplicates)
+
+Notes (be sure to tell this to your agents, too):
+- Use `gh` to interact with Github, rather than web fetch
+- Do not use other tools, beyond `gh` (eg. don't use other MCP servers, file edit, etc.)
+- Make a todo list first
+- For your comment, follow the following format precisely (assuming for this example that you found 3 suspected duplicates):
+
+---
+
+Found 3 possible duplicate issues:
+1. #123: Issue title here
+2. #456: Another issue title  
+3. #789: Third issue title
+
+This issue will be automatically closed as a duplicate in 3 days.
+- If your issue is a duplicate, please close it and 👍 the existing issue instead
+- To prevent auto-closure, add a comment or 👎 this comment
+
+---
\ No newline at end of file
diff --git a/.github/workflows/auto-close-duplicates.yml b/.github/workflows/auto-close-duplicates.yml
new file mode 100644
index 000000000..40e85c7a9
--- /dev/null
+++ b/.github/workflows/auto-close-duplicates.yml
@@ -0,0 +1,28 @@
+name: Auto-close duplicate issues
+description: Auto-closes issues that are duplicates of existing issues
+on:
+  schedule:
+    - cron: "0 9 * * *" # Run daily at 9 AM UTC
+  workflow_dispatch:
+
+jobs:
+  auto-close-duplicates:
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    permissions:
+      contents: read
+      issues: write
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Install uv
+        uses: astral-sh/setup-uv@v4
+
+      - name: Auto-close duplicate issues
+        run: uv run scripts/auto_close_duplicates.py
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          GITHUB_REPOSITORY_OWNER: ${{ github.repository_owner }}
+          GITHUB_REPOSITORY_NAME: ${{ github.event.repository.name }}
diff --git a/.github/workflows/claude-dedupe-issues.yml b/.github/workflows/claude-dedupe-issues.yml
new file mode 100644
index 000000000..1dda73be6
--- /dev/null
+++ b/.github/workflows/claude-dedupe-issues.yml
@@ -0,0 +1,37 @@
+name: Marvin Issue Dedupe
+description: Automatically dedupe GitHub issues using Marvin
+on:
+  issues:
+    types: [opened]
+  workflow_dispatch:
+    inputs:
+      issue_number:
+        description: "Issue number to process for duplicate detection"
+        required: true
+        type: string
+
+jobs:
+  claude-dedupe-issues:
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    permissions:
+      contents: read
+      issues: write
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Generate Marvin App token
+        id: marvin-token
+        uses: actions/create-github-app-token@v1
+        with:
+          app-id: ${{ secrets.MARVIN_APP_ID }}
+          private-key: ${{ secrets.MARVIN_APP_PRIVATE_KEY }}
+
+      - name: Run Marvin slash command
+        uses: anthropics/claude-code-base-action@beta
+        with:
+          prompt: "/dedupe ${{ github.repository }}/issues/${{ github.event.issue.number || inputs.issue_number }}"
+          anthropic_api_key: ${{ secrets.ANTHROPIC_API_KEY }}
+          github_token: ${{ steps.marvin-token.outputs.token }}
diff --git a/scripts/auto_close_duplicates.py b/scripts/auto_close_duplicates.py
new file mode 100644
index 000000000..34732c676
--- /dev/null
+++ b/scripts/auto_close_duplicates.py
@@ -0,0 +1,322 @@
+#!/usr/bin/env python
+# /// script
+# requires-python = ">=3.10"
+# dependencies = [
+#     "httpx",
+# ]
+# ///
+"""
+Auto-close duplicate GitHub issues.
+
+This script runs on a schedule to automatically close issues that have been
+marked as duplicates and haven't received any preventing activity.
+"""
+
+import os
+from dataclasses import dataclass
+from datetime import datetime, timedelta, timezone
+
+import httpx
+
+
+@dataclass
+class Issue:
+    """Represents a GitHub issue."""
+
+    number: int
+    title: str
+    state: str
+    created_at: str
+    user_id: int
+    user_login: str
+
+
+@dataclass
+class Comment:
+    """Represents a GitHub comment."""
+
+    id: int
+    body: str
+    created_at: str
+    user_id: int
+    user_login: str
+    user_type: str
+
+
+@dataclass
+class Reaction:
+    """Represents a reaction on a comment."""
+
+    user_id: int
+    user_login: str
+    content: str
+
+
+class GitHubClient:
+    """Client for interacting with GitHub API."""
+
+    def __init__(self, token: str, owner: str, repo: str):
+        self.token = token
+        self.owner = owner
+        self.repo = repo
+        self.headers = {
+            "Authorization": f"token {token}",
+            "Accept": "application/vnd.github.v3+json",
+        }
+        self.base_url = f"https://api.github.com/repos/{owner}/{repo}"
+
+    def get_open_issues(
+        self, created_before: datetime, page: int = 1, per_page: int = 100
+    ) -> list[Issue]:
+        """Fetch open issues created before a certain date."""
+        url = f"{self.base_url}/issues"
+        issues = []
+
+        with httpx.Client() as client:
+            response = client.get(
+                url,
+                headers=self.headers,
+                params={"state": "open", "per_page": per_page, "page": page},
+            )
+
+            if response.status_code != 200:
+                print(f"Error fetching issues: {response.status_code}")
+                return issues
+
+            data = response.json()
+            for item in data:
+                # Skip pull requests
+                if "pull_request" in item:
+                    continue
+
+                created_at = datetime.fromisoformat(
+                    item["created_at"].replace("Z", "+00:00")
+                )
+                if created_at <= created_before:
+                    issues.append(
+                        Issue(
+                            number=item["number"],
+                            title=item["title"],
+                            state=item["state"],
+                            created_at=item["created_at"],
+                            user_id=item["user"]["id"],
+                            user_login=item["user"]["login"],
+                        )
+                    )
+
+        return issues
+
+    def get_issue_comments(self, issue_number: int) -> list[Comment]:
+        """Fetch all comments for an issue."""
+        url = f"{self.base_url}/issues/{issue_number}/comments"
+        comments = []
+
+        with httpx.Client() as client:
+            page = 1
+            while True:
+                response = client.get(
+                    url, headers=self.headers, params={"page": page, "per_page": 100}
+                )
+
+                if response.status_code != 200:
+                    break
+
+                data = response.json()
+                if not data:
+                    break
+
+                for comment_data in data:
+                    comments.append(
+                        Comment(
+                            id=comment_data["id"],
+                            body=comment_data["body"],
+                            created_at=comment_data["created_at"],
+                            user_id=comment_data["user"]["id"],
+                            user_login=comment_data["user"]["login"],
+                            user_type=comment_data["user"]["type"],
+                        )
+                    )
+
+                page += 1
+                if page > 10:  # Safety limit
+                    break
+
+        return comments
+
+    def get_comment_reactions(
+        self, issue_number: int, comment_id: int
+    ) -> list[Reaction]:
+        """Fetch reactions for a specific comment."""
+        url = f"{self.base_url}/issues/{issue_number}/comments/{comment_id}/reactions"
+        reactions = []
+
+        with httpx.Client() as client:
+            response = client.get(url, headers=self.headers)
+
+            if response.status_code != 200:
+                return reactions
+
+            data = response.json()
+            for reaction_data in data:
+                reactions.append(
+                    Reaction(
+                        user_id=reaction_data["user"]["id"],
+                        user_login=reaction_data["user"]["login"],
+                        content=reaction_data["content"],
+                    )
+                )
+
+        return reactions
+
+    def close_issue(self, issue_number: int, comment: str) -> bool:
+        """Close an issue with a comment."""
+        # First add the comment
+        comment_url = f"{self.base_url}/issues/{issue_number}/comments"
+        with httpx.Client() as client:
+            response = client.post(
+                comment_url, headers=self.headers, json={"body": comment}
+            )
+
+            if response.status_code != 201:
+                print(f"Failed to add comment to issue #{issue_number}")
+                return False
+
+        # Then close the issue
+        issue_url = f"{self.base_url}/issues/{issue_number}"
+        with httpx.Client() as client:
+            response = client.patch(
+                issue_url, headers=self.headers, json={"state": "closed"}
+            )
+
+            return response.status_code == 200
+
+
+def find_duplicate_comment(comments: list[Comment]) -> Comment | None:
+    """Find a bot comment marking the issue as duplicate."""
+    for comment in comments:
+        # Check for the specific duplicate message format
+        body_lower = comment.body.lower()
+        if (
+            "possible duplicate issue" in body_lower
+            and "this issue will be automatically closed as a duplicate" in body_lower
+        ):
+            return comment
+    return None
+
+
+def should_close_as_duplicate(
+    issue: Issue,
+    duplicate_comment: Comment,
+    all_comments: list[Comment],
+    reactions: list[Reaction],
+) -> bool:
+    """Determine if an issue should be closed as duplicate."""
+
+    # Check if comment is old enough (3 days)
+    comment_date = datetime.fromisoformat(
+        duplicate_comment.created_at.replace("Z", "+00:00")
+    )
+    three_days_ago = datetime.now(timezone.utc) - timedelta(days=3)
+
+    if comment_date > three_days_ago:
+        return False
+
+    # Check for preventing reactions (thumbs down)
+    for reaction in reactions:
+        if reaction.content in ["-1", "confused"]:
+            print(
+                f"Issue #{issue.number}: Has preventing reaction from {reaction.user_login}"
+            )
+            return False
+
+    # Check for user activity after the duplicate comment
+    for comment in all_comments:
+        comment_date_check = datetime.fromisoformat(
+            comment.created_at.replace("Z", "+00:00")
+        )
+        if comment_date_check > comment_date:
+            # Issue author commented after duplicate marking
+            if comment.user_id == issue.user_id:
+                print(
+                    f"Issue #{issue.number}: Author commented after duplicate marking"
+                )
+                return False
+
+    return True
+
+
+def main():
+    """Main entry point for auto-closing duplicate issues."""
+    print("[DEBUG] Starting auto-close duplicates script")
+
+    # Get environment variables
+    token = os.environ.get("GITHUB_TOKEN")
+    if not token:
+        raise ValueError("GITHUB_TOKEN environment variable is required")
+
+    owner = os.environ.get("GITHUB_REPOSITORY_OWNER", "jlowin")
+    repo = os.environ.get("GITHUB_REPOSITORY_NAME", "fastmcp")
+
+    print(f"[DEBUG] Repository: {owner}/{repo}")
+
+    # Initialize client
+    client = GitHubClient(token, owner, repo)
+
+    # Get issues created more than 3 days ago
+    three_days_ago = datetime.now(timezone.utc) - timedelta(days=3)
+
+    all_issues = []
+    page = 1
+
+    while page <= 20:  # Safety limit
+        issues = client.get_open_issues(three_days_ago, page=page)
+        if not issues:
+            break
+        all_issues.extend(issues)
+        page += 1
+
+    print(f"[DEBUG] Found {len(all_issues)} open issues created more than 3 days ago")
+
+    processed_count = 0
+    closed_count = 0
+
+    for issue in all_issues:
+        processed_count += 1
+
+        if processed_count % 10 == 0:
+            print(f"[DEBUG] Processed {processed_count}/{len(all_issues)} issues")
+
+        # Get comments for this issue
+        comments = client.get_issue_comments(issue.number)
+
+        # Look for duplicate marking comment
+        duplicate_comment = find_duplicate_comment(comments)
+        if not duplicate_comment:
+            continue
+
+        print(f"[DEBUG] Issue #{issue.number} has duplicate comment")
+
+        # Get reactions on the duplicate comment
+        reactions = client.get_comment_reactions(issue.number, duplicate_comment.id)
+
+        # Check if we should close
+        if should_close_as_duplicate(issue, duplicate_comment, comments, reactions):
+            close_message = (
+                "Closing this issue as a duplicate based on the automated analysis above.\n\n"
+                "The duplicate issues identified contain existing discussions and potential solutions. "
+                "Please add your 👍 to those issues if they match your use case.\n\n"
+                "If this was closed in error, please leave a comment explaining why this is not "
+                "a duplicate and we'll reopen it."
+            )
+
+            if client.close_issue(issue.number, close_message):
+                print(f"[SUCCESS] Closed issue #{issue.number} as duplicate")
+                closed_count += 1
+            else:
+                print(f"[ERROR] Failed to close issue #{issue.number}")
+
+    print(f"[DEBUG] Processing complete. Closed {closed_count} duplicate issues")
+
+
+if __name__ == "__main__":
+    main()