A JSON encoder/decoder that rejects NaN, Infinity, and -Infinity and escapes problematic Unicode sequences (surrogate pairs, line/paragraph separators). Provides a drop-in replacement for stdlib json with strict mode enabled by default. Easily extractable for any project requiring safe JSON serialization of untrusted data.

Implements per-session state persistence using JSON files with fcntl file locking, TTL-based stale entry expiry, and garbage collection. Provides atomic read/write operations (`with_locked_state`) that can be safely used across concurrent hook invocations. Reusable in any multi-process hook system needing persistent state.

Loads user-defined hook rules from `.claude/hookify.*.local.md` files, parses YAML frontmatter for metadata, and evaluates rules against incoming tool calls. Supports filter-based triggers (tool name, arguments) and configurable actions (warn, deny, log). Demonstrates a clean separation between rule loading, parsing, and evaluation that could be adapted for any extensible hook system.

A workflow script for batch version migration (e.g., .NET 4.8→8, Java 8→17) that uses a playbook-driven fan-out pattern. Runs pilot migration on a representative unit, captures a playbook, then fans out across remaining units respecting dependency ordering. Implements a circuit breaker (build rate < 2/3 stops execution), pass-through of migration results for re-processing, and validation via dual-target test harnesses. The pattern is reusable for any batch transformation task with dependency constraints.