Stack Overflow Duplicate Question Flagger

WHAT IT DOES

Stack Overflow Duplicate Question Flagger automatically scans Stack Overflow question pages to detect when a question has been marked as a duplicate. It extracts the original question ID from duplicate notices, comment flags, and even page titles, then displays a prominent flag badge near the question showing where the original is located. The badge includes a direct link to the original question, saving you from hunting through comments or scrolling to find the duplicate notice. The tool also highlights duplicate-marked questions with a yellow border for instant visual recognition, and tracks duplicate status per question so you know at a glance whether a question has been flagged.

WHERE IT RUNS

This extension works exclusively on Stack Overflow question pages at stackoverflow.com/questions/*. It functions on all question pages, including those with duplicate status markers in the header, comment sections, or any part of the page. The tool integrates with Stack Overflow's page structure and respects the existing duplicate notice system.

HOW TO USE

Install the extension and navigate to any Stack Overflow question page. If the question has been flagged as a duplicate, a flag badge appears automatically near the question title. The badge shows "Duplicate: Original Question Title" with a "View Original" link that opens the original question in a new tab. Use the panel settings to choose between displaying the badge at the top of the question or inline with the question content. Toggle "Highlight duplicate questions" to add a yellow border to questions marked as duplicates. Click "Scan for Duplicate Flags" to manually refresh the detection. The tool also stores duplicate status locally, so you can see at a glance which questions you have already identified as duplicates.

TECHNICAL SECTION — MULTI-SOURCE DUPLICATE DETECTION

The extension uses a comprehensive detection strategy that searches multiple page locations for duplicate references. It first scans the question header for Stack Overflow's official duplicate notice, which contains links to the original question. It then parses all comment bodies for phrases like "duplicate," "marked as duplicate," or "possible duplicate," extracting question IDs from any linked URLs. As a fallback, the tool checks the page title for duplicate markers used in some Stack Overflow contexts. Each detection method extracts the original question ID using regex pattern matching against the /questions/(\d+) URL pattern. The tool then builds a flag badge with the original question title and a clickable link. A MutationObserver monitors page changes to re-run detection when the page updates dynamically.

THE PANEL — DRAG / PER-SITE POSITION / SNAP / COLLAPSE / RESIZE / ESCAPE

The overlay panel is fully interactive and designed for seamless multitasking. Drag it anywhere on the screen using the handle at the top of the panel; the position is saved per site so it stays where you left it across sessions. The panel includes a snap-to-edge feature that gently anchors the overlay to the nearest screen edge when released. Click the collapse button to minimize the panel to a compact pill showing the current duplicate status; expand it again with a single click. Resize the panel vertically by dragging the bottom-right corner to view more controls. Press the Escape key at any time to instantly close the overlay; it reappears on the next page navigation or refresh.

PLEASE NOTE

This extension requires the free BotGentz companion extension to function, as it provides the underlying content script injection and cross-origin communication framework. No personal data, browsing history, or Stack Overflow activity is stored, transmitted, or shared. Duplicate status flags are stored locally in your browser using GM_setValue and are never sent to any external server. The extension does not access or store login credentials, financial data, or personally identifiable information. Stack Overflow may update its page structure or duplicate notice layout; the extension includes multiple detection fallbacks to maintain compatibility, but major redesigns may temporarily affect detection. The tool reads duplicate status from the page and does not modify Stack Overflow's official duplicate marking system or voting functionality.