01 // RUNTIME PROOF CHOP & SEAM LEDGER

LET AGENTS BUILD FAST. PROVE THE UI SURVIVES REAL STATES.

■ LOADING ■ EMPTY ▲ ERROR ■ OFFLINE 04 STATES / 01 PROOF CARD

Interception in a controlled browser. No MSW, no proxy, no app edits. Forces loading, empty, error, and offline.

$ npx @stateproof-dev/cli init --url http://localhost:5173 --route /account/settings

account-settings.loading.desktop.png

1440×1024

PASS 3.1s · DESKTOP

02 // THE MECHANISM SYNTHETIC RUNTIME INJECTION

The happy path is not proof.

Four synthetic responses injected before your UI renders. Zero app instrumentation.

ID STATE FORCED RESPONSE EXPECTED SELECTOR STATUS

01 LOADING response: delay 3000ms expect [data-state='loading'] ■ PASS

02 EMPTY response: fixture account-empty.json expect [data-state='empty'] ■ PASS

03 ERROR response: error 500

retry control missing < 420px → FAIL

hint: render a retry control below 420px

expect [data-state='error'] ▲ FAIL

04 OFFLINE response: abort internetdisconnected expect [data-state='offline'] ■ PASS

Default viewports: desktop 1440×1024 · mobile 390×844 Exit codes: 0 (PASS) · 1 (FAIL) · 2 (ERROR) · 3 (TIMEOUT) · 4 (CRASH)

03 // THE WORKFLOW THREE-STATION PIPELINE

CHOOSE A REQUEST

Pinpoint the network route that populates your component.

GET /api/account

FORCE A STATE

Inject error status, artificial delay, or empty fixture payload.

"mode": "error" | 500

CAPTURE PROOF

Record screenshot evidence, Stateproof Card, and offline report.

PASS / FAIL + screenshot

delay 3000ms ▪ fixture account-empty.json ▪ status 500 ▪ internetdisconnected ▪ exit 0 ▪ exit 1 ▪ [data-state='loading'] ▪ viewport 1440×1024 ▪ Chromium 141 ▪ loopback guardrail ▪ zero telemetry ▪ delay 3000ms ▪ fixture account-empty.json ▪ status 500 ▪ internetdisconnected ▪ exit 0 ▪ exit 1 ▪ [data-state='loading'] ▪ viewport 1440×1024 ▪ Chromium 141 ▪ loopback guardrail ▪ zero telemetry

04 // THE EXPERIENCE EVIDENCE & CARD REPORTING

How runtime proof works beside your stack.

Stateproof runs beside npm run dev against your localhost in a dedicated headless Chromium instance. There is no mock service worker, no local reverse proxy, and zero modifications to your source code.

A scenario file is strict, typed JSON. When testing empty states, responses are explicit fixtures—Stateproof never guesses your application’s empty data shape.

Every run collects concrete evidence: full-resolution viewport screenshots, a markdown Stateproof Card for pull requests, and a standalone offline HTML report that opens directly from file:// with zero network dependency.

CONTRACT INTEGRITY FROZEN CLI FLAGS

--url --route --force --scenario --viewport --timeout-ms --allow-remote --reporter

STATEPROOF CARD ARTIFACT

MARKDOWN ENVELOPE

## Stateproof Card — Account settings

State	desktop	mobile
Loading	PASS	PASS
Empty	PASS	PASS
Error	PASS	FAIL

Artifacts: artifacts/stateproof/account-settings/ — account-loading.desktop.png · …

Run: local · Stateproof 0.1.0 · Chromium 141 · runId 01J9ZK84 · 2026-08-23T14:02:15Z

HTML REPORT: file:///artifacts/stateproof/report.html ZERO NETWORK

05 // INTERACTIVE DEMO LIVE SWITCHBOARD & CHROMIUM PREVIEW

Force the state. Capture the proof.

Test how an account settings UI reacts across desktop and mobile viewports.

1. FORCE STATE

2. VIEWPORT

3. EXECUTE

http:// localhost:5173 /account/settings INTERCEPT: DELAY 3000ms

1440×1024

LIVE SERVER

⌧

No Connected Organizations

This account currently has no active team memberships or API tokens.

The account settings service returned an unhandled server exception.

Organization Name

Changes cannot be saved while offline. Reconnect to resume sync.

Alex Rivera

alex@runtime-foundry.io

Billing Organization

Active API Key

RESULT ENVELOPE: READY ▪ Select state and press RUN PROOF

IDLE

06 // INTEGRITY LOCAL-FIRST ARCHITECTURE

Local-first by architecture, not by promise.

Built for security-conscious teams. Interception lives in our browser process, never in your code.

ZERO TELEMETRY

No telemetry, analytics, or background pings. Nothing leaves your machine unless you explicitly export or commit the artifact directory.

CONTROLLED CHROMIUM PROCESS

Network interception happens inside the Chromium instance launched by Stateproof via Playwright CDP. No production proxies, no monkey-patching.

LOOPBACK GUARDRAIL

Interception is strictly restricted to localhost and 127.0.0.1 by default. External origins require the explicit --allow-remote flag.

DISK-ONLY ARTIFACTS

Screenshots, JSON envelopes, and reports write to ./artifacts on local disk. You control your git history and CI attachments.

OFFLINE HTML REPORT

The generated test report is a standalone HTML document with inline styles and assets. It opens directly from file:// with zero network requests.

07 // RUN PROOF FIRST-RUN INVITATION

PROVE YOUR RUNTIME
IN FOUR COMMANDS.

Drop Stateproof into your project. Intercept real runtime failure modes against localhost in under 60 seconds.

BASH / TERMINAL

NODE ≥ 20

$ npx @stateproof-dev/cli init --url http://localhost:3000 --route /settings

$ npx @stateproof-dev/cli --tui # launch interactive studio

$ npx @stateproof-dev/cli run # capture proof cards

GITHUB REPOSITORY ↗

■ Captured, not guaranteed. No telemetry, no cloud dependencies.

stdout // stateproof run

EXIT 0

✔ CDP browser connected (Chromium 141)

✔ Intercepting route: /account/settings

01 LOADING 3000ms delay PASS

02 EMPTY account-empty.json PASS

03 ERROR HTTP 500 response PASS

04 OFFLINE aborted socket PASS

RESULT: 4/4 passed (100%) · 0 warnings

TIME: 2.84s total · 0 telemetry pings

SAVED: ./artifacts/stateproof/01J9ZK84/

VERIFIED LOCAL ENGINE · EXIT 0