# Url To Screenshot Runtime

> Runtime engine for url-to-screenshot. Use to detect a browser, capture and verify a URL-to-PNG result, browser-print and structurally inspect a PDF, or run the offline self-test of the deterministic core, without network, package installation, or live browser launch in the smoke path.

- Skill: `hoanganhduc/url-to-screenshot-runtime` (Agent Skill)
- Install (CLI): `npx skillmds@latest add hoanganhduc/url-to-screenshot-runtime`
- Raw SKILL.md: https://api.skillmd.com/api/skills/hoanganhduc/url-to-screenshot-runtime/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Docs & Writing
- Author: hoanganhduc (https://skillmd.com/u/hoanganhduc)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/hoanganhduc/url-to-screenshot-runtime

---


# URL to Screenshot Runtime

This companion skill provides the executable engine for the `url-to-screenshot`
skill: browser detection, the fail-closed SSRF URL-admission gate, headless CDP
capture, cookie-consent dismissal, blank-output detection, the artifact-truth
`verify` gate, and an offline `selftest`.

It is intentionally runtime-backed and is installed only for targets that support
runtime skill helpers. It is not an OpenClaw skill-file target.

## Windows Runtime Commands

On native Windows, use the managed Windows runner and the native runtime command
target. Set `$runtime` to the installed runtime root. Multi-agent installs usually
use `%LOCALAPPDATA%\ai-agents-skills\runtime`.

```powershell
$runtime = if ($env:AAS_RUNTIME_ROOT) { $env:AAS_RUNTIME_ROOT } else { "$env:LOCALAPPDATA\ai-agents-skills\runtime" }
& "$runtime\run_skill.ps1" "skills/url-to-screenshot-runtime/run_url_to_screenshot.ps1" doctor
& "$runtime\run_skill.ps1" "skills/url-to-screenshot-runtime/run_url_to_screenshot.ps1" doctor
```

POSIX examples below use `run_skill.sh` and the `.sh` command target.

## Commands

From a configured ai-agents-skills runtime, prefer:

```bash
bash "${AAS_RUNTIME_ROOT:-$HOME/.local/share/ai-agents-skills/runtime}/run_skill.sh" skills/url-to-screenshot-runtime/run_url_to_screenshot.sh selftest
```

Common commands:

```bash
bash "${AAS_RUNTIME_ROOT:-$HOME/.local/share/ai-agents-skills/runtime}/run_skill.sh" skills/url-to-screenshot-runtime/run_url_to_screenshot.sh doctor
```

```bash
bash "${AAS_RUNTIME_ROOT:-$HOME/.local/share/ai-agents-skills/runtime}/run_skill.sh" skills/url-to-screenshot-runtime/run_url_to_screenshot.sh capture --url https://example.com/ --out shot.png
```

```bash
bash "${AAS_RUNTIME_ROOT:-$HOME/.local/share/ai-agents-skills/runtime}/run_skill.sh" skills/url-to-screenshot-runtime/run_url_to_screenshot.sh verify --png shot.png --expected-width 1280 --expected-height 800
```

```bash
bash "${AAS_RUNTIME_ROOT:-$HOME/.local/share/ai-agents-skills/runtime}/run_skill.sh" skills/url-to-screenshot-runtime/run_url_to_screenshot.sh print-pdf --url https://example.com/ --out page.pdf --same-origin-only
```

```bash
bash "${AAS_RUNTIME_ROOT:-$HOME/.local/share/ai-agents-skills/runtime}/run_skill.sh" skills/url-to-screenshot-runtime/run_url_to_screenshot.sh verify-pdf --pdf page.pdf
```

## Verbs

- `doctor` — report capture readiness (browser, ImageMagick, Pillow); installs
  nothing; fail-soft to `missing` / `BLOCKED_ENVIRONMENT`. This is the only
  surface that reports whether a real capture is possible.
- `capture` — capture a URL to a PNG. The target URL is admitted through the
  fail-closed SSRF gate before any browser launch. A full-page result includes
  measured layout/pixel dimensions and a completeness attestation; the request
  flag alone is not evidence that the whole top-level layout was captured.
- `verify` — the artifact-truth gate: `final_verdict=VERIFIED` only when
  file/decode/dimensions/not-blank/consent all PASS; otherwise a structured
  `BLOCKED_*` / `UNVERIFIED`. Nothing else declares success.
- `print-pdf` — browser-print a bounded PDF through the guarded CDP path.
  `--same-origin-only` aborts if any paused redirect or sub-resource changes the
  initial origin tuple: scheme, canonical hostname, or effective port (explicit
  port, otherwise 80 for HTTP and 443 for HTTPS).
- `verify-pdf` — conservative bounded structure inspection. A sound classic
  page tree returns `status=STRUCTURALLY_VALID` but always
  `final_verdict=UNVERIFIED`, because parsing alone cannot prove that rendered
  pages are visually nonblank. The command exits 0 for this structural-only
  success so it remains scriptable; pair it with an independent visual gate
  when a final proof decision is required.
- `selftest` — offline smoke (no network, no browser launch, no socket, no
  package install). Prints a JSON contract and exits nonzero on any failure.

## Guarantees

The `selftest` path:

- uses only the Python standard library
- does not require network access
- does not install packages
- does not start servers
- does not launch a browser or open a socket
- synthesizes all PNG test bytes in memory (no committed binary fixtures, and it
  never reads the committed HTML capture fixtures)

`websocket-client`, `Pillow`, and ImageMagick are optional; the engine and the
offline self-test run with no third-party packages. A host browser
(Chromium/Chrome/Edge) is an optional system tool surfaced by `doctor`, never an
install gate.

Real capture and print results include `runtime_version` and the detected
browser's bounded `--version` probe. Guarded CDP results also include
`navigation_complete=true` only after the requested frame/loader emits its own
load lifecycle event. Full-page PNG results additionally include
`document_ready_state=complete`; the runtime remeasures after capture and does
not publish a false completeness attestation if the document grew beyond the
admitted clip. The offline self-test does not run the browser version probe.

Use the canonical `url-to-screenshot` skill for the user-facing workflow and
this helper only for the executable engine.