Capture and persist browser screenshots or GIFs for visual review of a web UI. Use when verifying a UI change visually, reviewing a page's design or layout, recording a multi-step interaction (dropdown, hover, form flow), toggling dark mode for a comparison shot, or when a screenshot needs to be written to disk rather than only shown inline.
Run and troubleshoot copier updates in a project generated from one of the user's templates, and maintain the templates themselves. Use when a task mentions copier, copier update, .copier-answers.yml, .rej files after an update, ctt or copier-template-tester, or one of calcipy_template, mdformat-plugin-template, my_go_template, or app-template.
Audit or write an hk.pkl config (jdx/hk git hooks). Use when creating hk.pkl, upgrading the pinned hk version, adding a linter step, or when fixes made by a pre-commit hook are not being staged. Covers version pinning, staging semantics, builtins, and DRY structure.
Query PostHog error tracking and Sentry issues from the command line. Use when asked what errors are happening, which errors are being missed or untriaged, for production error rates or impact by user, or whenever posthog-cli or sentry-cli is mentioned.
Work a multi-phase plan to completion with subagents, checkpoint commits, and questions back to the user. Invoke explicitly with a plan document.
Async Python conventions and footguns — asyncio.TaskGroup over gather, event-loop-bound primitives, offloading blocking work to threads or processes, cancellation across the thread boundary, and dedicated executors. Use when writing or reviewing async def, await, asyncio.to_thread, run_in_executor, create_task, async generators, or when diagnosing a stalled event loop, a "bound to a different event loop" error, or latency that only appears under load.
The user's full writing system for prose they author — README and docs text, landing copy, PR and commit descriptions, Linear proposals, design docs, Slack and email messages. Use when drafting or rewriting any human-facing prose, when a draft reads like AI wrote it, when stripping AI slop from documentation, or when relaying research output into a human-facing surface. CLAUDE.md carries the compressed rules; this carries the reasoning, the before/after pairs, and the per-format shapes.
Audit a repository's state and condense scattered notes into a phased ROADMAP.md. Invoke explicitly.