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Calculate mouse position in rotated div

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Summary The problem of calculating mouse position in a rotated and scaled DIV is a complex one, involving DOMMatrix and coordinate transformations. To solve this, we need to understand how to apply transformations to the mouse coordinates. Root Cause The root cause of this issue is the nested transformation of the DIV elements, which affects … Read more

Capturing sudoku but Selenium didn’t find it with Chrome in HTML

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## Summary A Selenium script successfully accepted cookies within an iframe but failed to locate a Sudoku board element. The issue occurred because the Sudoku board rendered dynamically **after** initial page loadículos and likely resided in a distinct document context (iframe or shadow DOM) that the script didn’t access. ##िपठत Root Cause * **Dynamic content … Read more

Hosting Ansible Playbook using Docker

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Summary The issue at hand involves Ansible playbooks running within a Docker container, which occasionally cause remote server VM hosts to reboot during execution. This problem does not occur when running the playbook outside of the Docker environment. The goal is to identify the root cause and find a solution to prevent these reboots. Root … Read more

List products that are viewed but not purchased by users

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## Summary A production incident occurred when querying **viewed-but-not-purchased** products returned incorrect results. The root cause was flawed JOIN logic and incorrect filtering conditions in SQL queries against the `user_behavior` dataset. Specifically: – **Missing correlation** between user behavior sessions and purchases – **Incorrect date handling** for purchase verification windows – **Failure to account for multi-product … Read more

How to enqueue CSS and JS properly in a WordPress theme?

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Summary The correct way to add CSS and JS files in a WordPress theme is by using wp_enqueue_style and wp_enqueue_script functions. This approach is preferred over directly adding files in the header.php file because it provides better control, flexibility, and performance. Root Cause The root cause of not using wp_enqueue_style and wp_enqueue_script is: Lack of … Read more

Why does WordPress recommend using hooks instead of editing core files?

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Summary WordPress mandates modifying behavior via hooks (actions and filters) rather than altering core files. This approach avoids system instability caused by overriding foundational code. This postmortem examines the architectural rationale and risks of bypassing hooks. Root Cause Direct core file edits lead to systemic fragility because: WordPress core updates replace files indiscriminately. Edits are … Read more

Why are MCPs needed at all?

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Summary The Model-Context-Protocol (MCP) is a new protocol that aims to standardize how agentic software invokes other tooling within systems, reducing the need for multiple connectors. However, with existing solutions like OpenAPI, WSDLs, and WADL, the question arises: why is MCP needed at all? This article explores the root cause of the need for MCP, … Read more

How to create custom REST API endpoint in WordPress plugin

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Summary Creating a custom REST API endpoint in a WordPress plugin involves registering a route and returning a JSON response. This is achieved by utilizing WordPress’s built-in REST API functionality, which allows developers to easily extend the API with custom endpoints. Root Cause The root cause of difficulties in creating custom REST API endpoints often … Read more

Redis issues: Account access not granted

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Redis Account Access Issue: Authentication Failure Analysis Summary A user reported一时无法访问他们的 Redis account, facing login denial due to an “invalid email” and registration rejection with “account already exists”. This was traced to inconsistent email normalization processes across authentication flows, causing credential mismatches. The system failed to provide account recovery options admin reporting channels exacerbated the … Read more