// Use this when adding Nix-based local runs for an existing Playwright e2e suite. Provides a self-contained `tests/shell.nix` that uses `nixpkgs-latest` for `playwright-driver.browsers`, plus a justfile entry — works on NixOS where `npx playwright install --with-deps` cannot.
Use this when setting up Nix for a development project (devShell + package build) and you care about `nix develop` being fast. Covers the zero-inputs flake.nix + npins + default.nix/shell.nix layout, sub-flakes for non-user-facing Nix, and language-specific recommendations.
Use this when a flake's `nix develop` / `direnv allow` / `nix flake archive` is slow on a fresh checkout (the "first time takes 10 minutes" complaint). Diagnoses where the time actually lives and how to shrink the flake.lock input graph without changing build outputs.
Write a programming essay or blog post in the voice of the canon — Spolsky, Yegge, Graham, Mickens, Dijkstra, Brooks, Nystrom, Kleppmann, patio11. Invoke when the user wants to argue an idea about software, architecture, languages, or the craft — not a debugging war story (use debugging-story for that), not a tutorial, not a release note. The audience is working developers worldwide with taste and strong opinions of their own.
Use this when setting up CI for a GitHub repository — offers GitHub Actions or Vira depending on the project
Use this when working on a Haskell project with Nix. Covers haskell-flake setup, adding/overriding dependencies, package settings, and devShell configuration.
Use this when diagnosing or fixing a user's Nix installation — checks flakes, version, caches, max-jobs, direnv, rosetta, trusted-users, and shell config
| name | nix-playwright |
| description | Use this when adding Nix-based local runs for an existing Playwright e2e suite. Provides a self-contained `tests/shell.nix` that uses `nixpkgs-latest` for `playwright-driver.browsers`, plus a justfile entry — works on NixOS where `npx playwright install --with-deps` cannot. |
For projects that already have a Playwright e2e suite (typically under tests/) and need it to run locally on NixOS / pure-Nix hosts, where Playwright's bundled Chromium download depends on apt-get + sudo.
GitHub Actions CI is left untouched — apt-provided Chromium on Ubuntu runners is cheaper than spinning up a Nix devshell. This skill is for local runs (and Nix-based CI like Vira); GHA continues to use its own apt path.
nixpkgs-latest flake inputIn top-level flake.nix, add an independent pin so the Playwright rev moves on its own cadence (decoupled from the main nixpkgs your build uses):
inputs.nixpkgs-latest.url = "github:nixos/nixpkgs/nixpkgs-unstable";
tests/shell.nixSelf-contained. Reads the parent flake's lock to resolve nixpkgs-latest without needing a flake context:
let
lock = builtins.fromJSON (builtins.readFile ../flake.lock);
nixpkgsLocked = lock.nodes.nixpkgs-latest.locked;
pkgs = import (builtins.fetchTree {
type = "github";
inherit (nixpkgsLocked) owner repo rev narHash;
}) { };
in
pkgs.mkShell {
packages = [ pkgs.nodejs ];
PLAYWRIGHT_BROWSERS_PATH = "${pkgs.playwright-driver.browsers}";
PLAYWRIGHT_SKIP_BROWSER_DOWNLOAD = "1";
}
e2e:
nix-shell tests/shell.nix --run "cd tests && { [ -d node_modules ] || npm ci; } && npm test"
pkgs.playwright-driver version must match the playwright version in tests/package.json. Drift raises "browser revision X not found at <PLAYWRIGHT_BROWSERS_PATH>" at launch.
Bump both together:
nix flake update nixpkgs-latestplaywright in tests/package.json to the new driver versionnpm install in tests/ to regenerate the lockfilePattern extracted from emanote#660.