Senior Web App Architect for Coding Agents

Turn any coding agent into a senior web architect. Eight files of production-audit judgement — the decisions, failure modes and orderings that separate apps that survive production from apps that get debugged there. If your agent writes web code, this is the skill it should be carrying.

The problem

Web applications fail in production because architectural decisions get made implicitly. The symptoms are always the same: content stays stale after an editor saves, hydration mismatch warnings, pages Google never indexes, social previews pointing at localhost, spam records appearing despite "validation", builds that only break on a clean clone, a site that gets a little slower every sprint — and security holes where the browser was trusted as a boundary. Generic AI output reproduces these failures, because the knowledge that prevents them is not in the docs. It is judgement.

What it does

• Rendering, decided per route — static, regenerated (ISR), server-rendered, streamed or client, chosen by four questions (differs per visitor? staleness tolerance? must it be indexed? cost to produce?) — plus an opinionated default posture: static shell with islands, purged automatically the moment an editor saves.
• Data and caching with one owner per fact — a reader pattern that never throws, per-record validation that drops one bad row instead of crashing the page, and writes paired with exactly the caches they invalidate. The "save button is broken" bug, designed out.
• A real security boundary — authorisation on an attribute the caller cannot self-assign, the six privilege-escalation shapes (self-promotion via writable records, open creates, unlisted upload paths, UI-filter "security" and more), the CSRF question, and the grant-then-tighten ordering that avoids locking your own admin out.
• SEO as architecture — canonical host discipline, honest status codes (no soft-404s), escaped structured data, breadcrumbs, and sitemaps enumerated from your datastore.
• Performance and assets, budgeted — images served at rendered size with the LCP image never lazy-loaded, fonts swapped without layout shift, JavaScript priced per route, third-party scripts governed like dependencies, and Core Web Vitals (LCP / INP / CLS at p75) mapped to their structural fixes.
• TypeScript and JavaScript defaults that are day-one-or-never — the compiler flags you cannot retrofit, typed boundaries, async discipline, and the money, date and JSON traps. Each item earns its place by the production failure it prevents.
• Verification drills — clean-clone builds, shipped-artefact checks, boundary probes (401 / 403 / 2xx), invalidation drills. The architecture gets proven, not intended.

Frameworks & tools

Stack-independent by design: Next.js, Nuxt, SvelteKit, Angular, Django, Rails, .NET — anything that serves HTML, with the framework vocabulary verified against current documentation. The language reference applies to any TypeScript or JavaScript codebase; the architecture applies regardless of language.

Why this beats prompting it yourself

A general model already knows what SSR and ISR are — nobody needs to buy definitions. What it reliably misses is when to choose which, what each choice costs, and how the wrong one fails. This skill encodes that judgement from audits of live production sites: the write-to-purge link whose absence gets reported as a broken save button, the escalation paths hiding behind client-side guards, the third-party tag audit nobody runs, the compiler settings that are day-one-or-never. Decisions and failure modes baked into the structure — not patched on after the incident.

Use cases

• Design the rendering and caching strategy for a content site or e-commerce catalogue, route by route.
• Audit an existing app for boundaries where the UI is the only gatekeeper.
• Debug stale-content reports by walking the invalidation path from write to CDN.
• Make generated detail pages discoverable: crawler-readable content, per-record structured data, datastore-driven sitemaps.
• Diagnose failing Core Web Vitals and fix them structurally — budgets, LCP priority, font swap, tag governance.
• Start a TypeScript project with the strict defaults that survive a clean-clone CI run.

What it deliberately is not

Application architecture only — honest scope is part of the product. It does not choose your stack, datastore or vendors; no framework tutorials, no UI design, no cloud-provider configuration, no native apps, no hosted CMS platforms (WordPress and similar). Every paragraph inside had to earn its place by encoding a decision or a failure mode; the padding was cut so your context window does not pay for it.

Compact by design: a lean SKILL.md loads on trigger; seven reference files load only when the agent needs that topic. One prevented incident — a leaked record, a locked-out admin, a week of stale-cache debugging — pays for this skill many times over.