Articles

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Write-ups of real engineering problems: what broke, how I found the cause, and the fix.

LatestDeveloper ToolingBuilding a Live Terminal Statusline for Claude Code: Tokens, Limits, and Responsive WrappingHow to design a resilient Bash statusline command for Claude Code that displays workspace context, token consumption, rolling rate limits, and ANSI color formatting without terminal overflow.September 17, 20268 min readRead →

September 2026

17ThuDatabase Systems6 min readSilent Grouping: How a Missing Field in MongoDB $group Generates Plausible False PositivesWhy referencing a non-existent field in a MongoDB aggregation pipeline succeeds without error, collapses documents into deceptive buckets, and fools developers through coincidental count matches.
17ThuCloud Architecture6 min readWhy encodeURIComponent Breaks S3 CopyObject with Silent NoSuchKey ErrorsHow a standard JavaScript URL encoding function silently breaks multi-segment S3 keys in CopyObjectCommand, producing deceptive NoSuchKey errors on objects that already exist.
15TueNetworking12 min readSSH KEX Hang: A VPN Tunnel at MTU 1500 is not a TunnelSSH connects, then dies mid-handshake. A local port-forward to a remote database cluster through a bastion stopped working, hanging on the first large packet of the SSH session. How an oversized MTU on a VPN interface created a silent black hole.
11FriLinux11 min readTerminal System Diagnostics: A Complete Picture Without GUI ToolsHow to get a single complete picture of a machine's OS, boot mode, disk layout, memory, GPU, and network from one terminal pass, without guessing. A structured approach to hardware and OS discovery.
07MonNetworking13 min readAWS IAM Identity Center Sign-In Failure Caused by an MTU Black HoleWhen the AWS access portal loads but authentication hangs indefinitely, the fault may lie below the application layer. How a 1478-byte path MTU and dropped ICMP messages created a silent TLS handshake black hole.
03ThuLinux10 min readAWS IAM Identity Center Sign-In Failure Caused by Host Clock SkewA generic AWS sign-in error and a misleading password reset failure traced back not to IAM permissions or account status, but to a 5-hour local clock skew caused by dual-boot RTC desynchronization.