Fix Solana token account errors - create missing associated token accounts, rent-exempt minimums, Token vs Token-2022 and reading simulation logs

Fix 502, 504 and timeouts in Netlify and Vercel functions - read function logs, plan limits, background functions, bundling and response shape and size

Text processing from the shell - awk column sums and filters, dedupe with seen[$0]++, sed substitution and -i.bak edits, CSV traps

SQLite maintenance - online backup API, VACUUM shrinking 2180 to 1092 KB, WAL and shm files, wal_checkpoint(truncate), integrity_check

YAML gotchas run live - NO becomes False, 01234 becomes 668, 12:30 becomes 750, 1.10 becomes 1.1, duplicate keys, safe_load

Fix WireGuard no handshake - key mismatch, UDP 51820 firewall, forwarding and NAT, AllowedIPs routing, overlapping subnets, keepalive, MTU

Build a safe x402 client - per-payment and daily caps, host and payee allowlists, identical-header retries after ambiguous settlement and payment receipts

Fix x402 settlement failures as a seller - facilitator limits, canary payments, fallback and replay-safe delivery

Verify webhook HMAC-SHA256 signatures - raw body not re-serialized JSON, timestamp tolerance, compare_digest and timingSafeEqual

Debug a failing x402 payment as a buyer - decode the challenge, balance, expired signatures and safe retry

Fix WebSocket disconnects and handshake errors - nginx Upgrade headers, idle timeouts, heartbeats, sticky load balancing and reconnect backoff

Unicode in Python - NFC vs NFD equality, casefold vs lower, zero-width characters, Cyrillic lookalikes, slugify returning empty for CJK

Fix viem and ethers RPC errors - rate limits and retries, fallback transports, eth_getLogs range limits, chain id checks and lagging nodes

Docker ignores UFW - published ports bypass rules; bind to 127.0.0.1, DOCKER-USER chain, internal networks, reverse proxy, external nmap check

Fix common TypeScript errors - TS2339, TS2322, TS7006, TS2307 and possibly undefined; narrowing, @types, ESM extensions, tsconfig settings

Test webhooks locally - Cloudflare Tunnel and ngrok, provider CLIs, request replay, raw-body signature checks and idempotent retry handling

Fix TLS certificate renewal failures - certbot logs, HTTP-01 and DNS-01 errors, rate limits and reload hooks

URL encoding cheat sheet - Python quote vs urlencode, JS encodeURIComponent vs URLSearchParams, + vs %20, parse_qs, base64url

Count LLM tokens with tiktoken - chars vs tokens table, emoji and digits cost, chunk by tokens with overlap, prompt budget formula

Pick IDs correctly - uuid4 unsorted, uuid1 leaks MAC, ULID order within a millisecond, UUID parse forms, uuid5 deterministic, secrets tokens