Recreate the Plenum (smart-thermostat-with-vents) development environment from scratch: prerequisites, backend pip install, frontend npm install/build, .env setup, VS Code launch configs, Docker image build, docker-compose test stack anatomy, and local E2E/Playwright setup. Load when setting up a fresh clone, when an install/build/test command fails with missing deps or wrong versions, when Vite/dev-server ports or proxies misbehave, or when you need to know where a build artifact or the SQLite DB lives. Do NOT load for actually running/operating the app (plenum-run-and-operate) or for CI workflow internals (plenum-ci-and-release).
Load this BEFORE making any change to the Plenum repo (smart-thermostat-with-vents) — adding a temperature field, config option, endpoint, dependency, UI change, or engine/safety-guard edit — or before opening/reviewing/merging a PR or cutting a release. Explains how changes are classified, which CI gates each class must clear, what evidence a reviewer expects, the non-negotiable rules with the historical incident behind each, and the release/branch-protection flow.
The CI/CD machine of Plenum (smart-thermostat-with-vents): every GitHub Actions workflow job-by-job, container-ci's three build modes (normal PR / release PR / fork PR) and the PLENUM_IMAGE handoff, the visual-regression golden-screenshot machinery (parallel F/C legs, update-then-verify, fan-in auto-commit bot), the tag→release-PR→publish release flow, branch protection, the failure-triage table for red checks, and the nightly ci-image cleanup. Load when a CI check fails, when a bot pushed "ci: update E2E golden screenshots" onto your branch, when cutting or validating a release, or when editing anything under .github/workflows/.
The chronicle of every settled battle in Plenum (smart-thermostat-with-vents) — major investigations, dead ends, rejected approaches, and reverts, each as symptom → root cause → evidence → fix → status. Load when you suspect a bug was seen before, when someone proposes re-fixing or weakening something (deadband in at-target, frontend toStorage on payloads, default-mapped MCP port, per-selector screenshot masks), when you need the incident behind a guard/test name, or before filing an issue that might duplicate #26–#369 history. NOT for live triage of a new symptom (use plenum-debugging-playbook) or for the invariant statements themselves (plenum-architecture-contract).
Executable, decision-gated campaign plan for Plenum issue #373 — adding authentication to the web UI (port 8099) and the MCP server (port 9099), which are BOTH unauthenticated today and rely entirely on Home Assistant ingress in front. Load when working on #373, when asked to design or implement auth/login/OAuth/bearer tokens/sessions for Plenum, when reasoning about ingress-vs-direct-port trust, MCP OAuth 2.1 authorization, or when someone proposes gating access by port number or trusting X-Ingress headers. This is a CANDIDATE plan, not decreed scope — the owner has not chosen an approach. NOT for general change-gating (load plenum-change-control) or the shipped MCP transport internals (plenum-architecture-contract).
The load-bearing design decisions of Plenum (smart-thermostat-with-vents), the invariants that must hold, WHY each exists, and the known-weak points. Load when you need the canonical temperature-unit contract (°F storage, single write boundary, #231), the component map with real file paths, the cycle-engine invariants (mode lock, in-place trigger updates, 60s tick), the MCP loopback design, or a "before you change X, understand Y" dependency check. Also load when CLAUDE.md prose seems to disagree with the repo — this skill flags the known drift.
Symptom-to-triage playbook for Plenum (smart-thermostat-with-vents). Load when something is behaving wrong at runtime and you need to find the cause fast — temperatures off by ~×1.8 or ~30°, cycles that never end or end early, vents thrashing or stuck open/closed, a zone the engine silently stopped controlling, timestamps shifted by hours, duplicated/zombie live-feed rows, HA entity or cover-service failures, wrong heat/cool mode or oscillation, or one of the three classic CI failures (golden-screenshot diff, TEMPERATURE_FIELDS parity, coverage gate). Gives ranked causes, the exact discriminating command/query/log line, and the issue precedent for each.
How to maintain Plenum's documents of record (README.md, DESIGN.md, CLAUDE.md, docs/*.md, CHANGELOG.md, RELEASE.md, screenshots/), the house prose style, and the external-claims discipline (test counts, coverage numbers, heat-pump non-support). Load when writing or editing any doc, refreshing the README "Tested" stats block, adding a docs/ feature page with a feature PR, amending CLAUDE.md after a hard-won lesson, or checking whether a documented number/path still matches the repo. Do NOT load for CI/release mechanics (plenum-ci-and-release) or PR gating rules (plenum-change-control).