agent-first-screenshots

Agent-First Screenshots

An agent-first screenshot is produced by an agent driving the real app via CDP, gated by structural + pixel + vision verification before it ships. It turns screenshots from hand-crafted artifacts into a regenerable pipeline.

Use this for "take/redo screenshots / make marketing images" tasks. It is NOT e2e evidence — for pass/fail proof use the fraimz skill.

The Zero-Defect Bar

A shippable screenshot has ZERO obvious visual defects — the bar is not "the content is present", it is: would a human glancing at it immediately spot something broken? Overlapping or clipped text, misaligned/collapsed layout, garbled or mid-transition content, blank regions, stray modals/tooltips — any of these disqualifies the frame. Full stop.

The One Method

Operate the app like a power user preparing a demo, not like a developer hacking the DOM. The app already looks great: get it into a real, settled state through the UI and capture it cleanly. Never rebuild or fake it.

Golden Rules

1. Only remove, never add. Hiding a leaf distraction (notification badge, "Sign in" footer link, status text) via display:none is safe. Never inject fake HTML, override flex/height/width on structural containers, add fixed-position overlays, or mutate the DOM tree — the layout engine will collapse (scroll areas shrink to 0, content disappears).
2. If a feature isn't available, don't fake it. Enable it through the settings UI like a real user, or skip the shot and say so.
3. Each shot starts from a clean reload. location.reload(), wait for full render, navigate through the UI, minimal leaf cleanup, verify, capture. Never carry CSS hacks across shots.
4. Get state naturally. Click the real tabs/buttons/pickers; close panels via their close buttons (not CSS); run real multi-turn tasks so content is impressive — no toy data, no mid-stream captures.
5. Match the target aspect ratio via CDP metrics override (e.g. 1440x900 at deviceScaleFactor: 2), then wait ~1s and re-verify — the override can trigger re-layout.

Verify with three channels, in a loop

innerText existing does not mean visible; a healthy DOM rect does not mean it rendered. Every frame must pass all three before it ships:

1. DOM pre-check (cheap, before capture): scroll area height > 100px (not collapsed), hero text inside the viewport rect, no unexpected modal/overlay. If it fails: reload and redo — never fix with more CSS.

2. Pixel post-check (truth, after capture): decode the PNG and sample the DOM-derived hero rects. Calibration: for text-on-white UI, background ratio is a bad signal (85–92% background is normal). Variance is the reliable signal: content-filled region variance > ~200 (often 1000+); blank/flat region < 50. Whole-image bgRatio > 0.97 → blank frame.

3. Vision check (mandatory gate): deterministic stats CANNOT catch the defects that matter most — overlap, clipping, misalignment, double-rendering. Hand the PNG to a vision-capable model with a zero-defect rubric returning JSON:

   { any_obvious_defect: bool,   // the gate — if true, REJECT
     overlapping_text_or_elements: bool, clipped_or_cutoff: bool,
     misaligned_or_broken_layout: bool, blank_or_empty_regions: bool,
     stray_modal_tooltip_or_panel: bool, legible: bool,
     polish_score: 1-5, defects: ["..."] }
   

   If any_obvious_defect is true the frame is rejected regardless of layers 1–2. Diagnose, fix the root cause (settle the state, close the picker, reload), recapture.

Reusable scripts in this skill's directory: screenshot-verify.mjs (verify an existing PNG) and capture-verify.mjs (capture at 2x + verify regions + save only on pass); both use sharp.

Common failure modes

Symptom	Fix
Overlapping/clipped text (layers 1–2 pass)	Unsettled/edit-mode/wrong-width state — settle, use preview mode, gate on vision
Blank screenshot / 32px scroll area	Structural element was CSS-hidden — reload, close panels via UI
Overlay (picker/modal) on every shot	It was opened and never closed — Escape before capturing
In DOM but not in pixels	Clipped/blank render — trust variance + vision, not innerText

Anti-patterns

Injecting fake components; overriding flex properties; fixed-position overlays; carrying state across shots; verifying via innerText only; proof-frame mindset (the goal is "I want that", not "it didn't crash").