Thread-safe in-memory pub-sub event bus with per-session ring buffer (cap 1000). Used for SSE streaming to the web UI. Demonstrates clean separation of concerns and reconnect replay via Last-Event-ID. Reusable in any application requiring real-time event streaming with minimal dependencies.

Atomic append to chat.jsonl via read-all + rewrite with .tmp rename, including orphan recovery for crash resilience. Solves a common data integrity problem in file-backed logging. The pattern is directly reusable for any append-only log that must survive process crashes.

Deterministic system prompt builder for Step-2 refinement. Includes baseline code, accumulated rcParams, and output contract. Demonstrates a clean pattern for constructing LLM prompts from structured data, ensuring reproducibility and traceability. Reusable for any multi-turn refinement workflow.

Shared subprocess registry with SIGTERM → 3s → SIGKILL cancel logic, thread-safe. Manages subprocesses keyed by (workdir, slot). Demonstrates robust process lifecycle management with timeout escalation. Reusable in any application that spawns and manages multiple subprocesses.

Dep-free Python syntax highlighter (~80 lines) for the Export Code modal. Tokenizes Python source into HTML spans with CSS classes. Demonstrates a self-contained, zero-dependency utility that can be extracted and used in any web application needing client-side code highlighting.

Generic weighted image similarity scorer for 3D candidate PNGs against a reference. Computes pixel similarity, edge structure, silhouette IoU, primary geometry, etc., with proxy scorecard dimensions and strict floor validation. Reusable for any image comparison task requiring multi-metric scoring with configurable weights.