Local Web Verification
Local web verification proves the app running on localhost behaves correctly in a real browser; it is narrower than browser automation and broader than one screenshot. Source: User request, 2026-06-27; Browser Automation and QA
When To Use This
Use this page after changing frontend code, auth flow, routing, API integration, styles, loading states, or any UI whose correctness depends on rendered browser behavior. Source: Frontend and Design Skills, 2026-06-27
Decision Matrix
| Need | Route | Verification |
|---|---|---|
| Smoke a local page | Browser tool or Frontend and Design Skills | HTTP status, title/body, console status |
| Lock regression | Browser Testing Skills | Passing test |
| Visual/layout check | Browser Testing Skills or browser-harness | Screenshot at target viewport |
| Debug DOM/CSS | Chrome DevTools MCP or agent-browser | DOM/computed-style evidence |
Core Model
Localhost verification has three layers: server availability, rendered behavior, and durable regression. A page returning 200 is not enough; a screenshot alone is not enough; a passing test without looking at the changed UI can still miss layout damage. Source: Browser Automation and QA, 2026-06-27
Tool And Skill Routing
Use the existing dev server when it is already running and owned by the user. Do not kill unrelated listeners. Use Playwright for stable checks, browser-harness/agent-browser for visual and exploratory passes, and keep browser artifacts cleaned up after the turn. Source: Skill Resolver; Agent Process Tracking, Audit, And Cleanup
Failure Modes
- Treating
curl -Ias proof of UI behavior. - Starting duplicate dev servers instead of checking existing listeners.
- Ignoring browser console errors.
- Verifying desktop only when the UI must work on mobile.
Evidence And Timeline
The proof bundle should include the command or browser route checked, viewport when relevant, console/network status, and the smallest test or screenshot that would catch the bug again. Source: Frontend and Design Skills; Browser Testing Skills
Concept Position
| Field | Value |
|---|---|
| Concept family | Agent harness and runtime primitives |
| Concept owned | Local web verification proves the app running on localhost behaves correctly in a real browser; it is narrower than browser automation and... |
| Category map | Concept System Map |
Timeline
- 2026-07-01 | Concepts category refresh added this page to the Agent harness and runtime primitives family, linked it to Concept System Map, and kept it standalone because it owns this reusable mental model: Local web verification proves the app running on localhost behaves correctly in a real browser; it is narrower than browser automation and... Source: User request, 2026-07-01
- 2026-06-27 | Canonical cluster page created to keep localhost verification distinct from generic browser automation and agent search. Source: User request, 2026-06-27