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📝 Recent Posts
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Reading 20K Notion Pages Without the API - Local Cache + My First Open Source PR -
The Cheapest Way to Pass Context to AI - A Features Tracking System -
How Auto-Documentation in Vibe Coding Reduced Bug Fix Time to 5 Minutes -
Believed "Alimtalk Sent Successfully" - No One Received Messages for a Month -
Surviving Without Foreign Keys: The Soft Reference Pattern with Strings -
Persona-Based Exploratory Testing: Finding Bugs as a Rushed Teacher, Tech-Challenged Assistant, and Mischievous Student -
Student+Guardian Registration: Why We Built a New 1-step API Instead of Combining Existing APIs in Frontend -
John Smith A, B, C... Building an Automatic Duplicate Name System -
Comparing 5 Row-Level Security Implementations and Selection GuideSeries Navigation Part 1: One Account, Multiple Schools, Multiple Roles Part 2: 4-Tier Security to Prevent Data Leaks in Multi-Tenancy Part 3: Multi-Campus, Multi-Role JWT Design and ThreadLocal Safety Part...
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Multi-Campus, Multi-Role JWT Design and ThreadLocal Safety -
4-Tier Security to Prevent Data Leaks in Multi-TenancySeries Navigation Part 1: One Account, Multiple Schools, Multiple Roles Part 2: 4-Tier Security to Prevent Data Leaks in Multi-Tenancy ← Current Part 3: Multi-Campus, Multi-Role JWT Design and ThreadLocal... -
One Account, Multiple Schools, Multiple Roles: CheckUS Multi-Tenant ArchitectureWhat is Multi-Tenancy? - CheckUS Architecture Series (1/5)
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Is Normalization Always Right? A Practical Look at DB Tradeoffs
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LocalTime vs LocalDateTime: Time Formatting Bug and UTC→KST ConversionTL;DR Using the same substring approach for both weekly schedules (LocalTime “09:00:00”) and temporary assignments (LocalDateTime “2025-01-12T09:00:00”) breaks everything. Weekly schedules have no timezone, while temporary assignments are in UTC...
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Marquee Selection Scroll Bug: 5 Failed Attempts to Learn How Coordinates Really WorkTL;DR Marquee selection breaks when scrolling. Don’t mix clientY with scrollTop. Use document coordinates from the start. With position: absolute, just use document coordinates directly - the browser handles the...
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React Query Multi-Tenant Caching: Why Query Keys Need Tenant IDsTL;DR Campus dropdown changes, data doesn’t. Why? React Query cache doesn’t know about tenant IDs. Add tenantId to query keys. Problem solved.
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Spring AOP: Replacing 860 Manual Logs with One AspectTL;DR Replaced 860 scattered logs with one AOP aspect. Passwords get filtered automatically, execution time gets logged automatically. Everything just works.
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Spring Security: Why @AuthenticationPrincipal Beats Custom @CurrentUserTL;DR Was building a custom @CurrentUser annotation. Found out Spring already has @AuthenticationPrincipal. Saved 2 hours of pointless work.
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Beyond Filtered Search: A Hybrid Tree Search UI Pattern That Shows Both Results and ContextTL;DR
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DTO Conversion: Controller or Service? - I Actually Researched ItTL;DR
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The Elusive Claude 'File has been unexpectedly modified' Bug: A Workaround SolutionIf you’ve suddenly started hitting the File has been unexpectedly modified error with Claude, you’re not going crazy (Well, maybe you are a little, thanks to this bug). It’s a...