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# stardust:diff — prototype ↔ build reconcile Two probes that compare a **source** prototype against a **built** page. They catch **disjoint** failure classes — run BOTH; either alone gives a false "looks fine". Both are framework-agnostic Playwright probes that compare two rendered URLs by **computed style + DOM** (not pixels). All stack-specific language lives in a **profile** (`--profile eds|generic`); the comparison logic is generic. ## When to use - After converting a prototype to EDS (the stardust `deploy` skill's Step 10) — use `--profile eds`. - Any "does the build match the design?" check between two rendered URLs (a Figma export vs a React build, a legacy page vs a rebuild) — use `--profile generic`. - Inside a conversion/QA workflow as the validation gate (see *Workflow use*). Not for: a single static file with no JS decoration (use the build/harness URL so components are decorated — a raw `.plain.html` has no roles to classify). ## The two probes | Probe | Script | Sees | Blind to | |---|---|---|---| | **Pixel / layout** | `skills/diff/scripts/visual-diff.mjs` | stretched images, dropped max-width wraps, blank renders, surface/ground colour flips, image-count gaps | "right text, wrong slot"; a dropped CTA (full pixels, plausible colours → no flag) | | **Structural content + type** | `skills/diff/scripts/content-diff.mjs` | MISSING / ROLE-SWAPPED headings·eyebrows·CTAs, invented/dropped body copy, rendered-FACE font forks (width probe); dropped `placeholder`/`aria-label`/`title` values, missing/wrong/moved icons — on the main root AND the `header`/`footer` chrome roots by default | geometry / layout regressions | `content-diff` extracts an ordered, role-classified inventory (`heading` / `eyebrow` / `cta`+href / `body`) from each root — the `--main` root(s) plus, by default, the `header` and `footer` chrome roots — classifying by **computed style + tag** so the prototype's DOM and the built DOM compare symmetrically, then diffs them root by root; a second inventory per root carries the `placeholder` / `aria-label` / `title` values and the icons. ## Run it ```bash # Prereq 0: playwright importable from the project root (node -e "import('playwright')"), else # npm i -D playwright pixelmatch pngjs cheerio --legacy-peer-deps # (never --no-save; extract SKILL.md § Setup). Run the copied scripts from the project # root: ESM resolves from the script. # Copy the WHOLE skills/diff/scripts/ dir: content-diff imports its local diff-profiles.mjs # AND content-inventory.mjs (deploy keeps its own synced copies for #93/#94). # Prereq: a RENDERABLE source. Static → serve from its own dir (python3 -m http.server). # The build URL must be the DECORATED page (live/preview or a local harness), not raw markup. # ONE server, ONE port — probe before starting one (curl is always present, lsof is not): curl -sI localhost:8791/ | head -1 # 200/404 = something serves the port; no line = free curl -sI localhost:8791/<prototype>.html | head -1 # 200 = it serves YOUR dir: reuse it command -v lsof >/dev/null && lsof -nP -iTCP:8791 -sTCP:LISTEN # optional: names the pid # Nothing answered → start yours. A foreign server: never kill it; use a per-project port # (the traps: ../deploy/SKILL.md § Step 10). PROTO="http://localhost:8791/<prototype>.html" BUILD="https://<branch>--<repo>--<owner>.aem.page/<path>" # or http://localhost:3000/<harness> # 1. PIXEL/layout node skills/diff/scripts/visual-diff.mjs "$PROTO" "$BUILD" --profile eds --sections ".hero" # 2. STRUCTURAL content + type node skills/diff/scripts/content-diff.mjs "$PROTO" "$BUILD" --profile eds # --json dumps both inventories ``` Flags (both tools): `--profile eds|generic` (default `eds`), `--width <px>` (default 1280), `--main <selector[,selector…]>` (content root; content-diff defaults from the profile and takes a comma-separated list — every root is inventoried and diffed on its own and each finding line carries its root as `[root]`; visual-diff takes one selector, default `main`), content-diff only: `--chrome` / `--no-chrome` (default on — the `header` and `footer` roots, resolved as the first `<header>`/`[role=banner]` and `<footer>`/`[role=contentinfo]` outside the main root(s), are compared beside it; a side lacking one is measured as empty there and the root line says so), plus the live-target set (shared engine: `scripts/live-session.mjs` — every context sends the real-Chrome UA **and** the standard Chrome request headers; the UA alone still 403s on Akamai-class bot management): - `--ua <string>` — user agent override (default: real-Chrome desktop UA). - `--wait-until <state>` — goto wait override. Default rule (one shared `defaultWaitUntil` in `scripts/live-session.mjs`), decided **per URL side**, three tiers: - localhost/127.0.0.1 → `networkidle` (local prototypes / harnesses, unchanged); - EDS build/preview origins — hostnames ending in `.aem.page`, `.aem.live`, `.hlx.page`, `.hlx.live` → `networkidle` (they decorate asynchronously and reliably reach networkidle; measuring at domcontentloaded reads the pre-decoration DOM — flaky false reds / FONT FORK on deploy Step 10); - all other live http(s) → `domcontentloaded` (live sites with analytics beacons never reach networkidle). `--wait-until` overrides all three tiers. - `--dismiss [sel,...]` — dismiss overlays on both sides: cookie consent (clicked, not removed) AND timed marketing/newsletter modals, plus optional extra site-specific selectors; the mouse is parked afterwards. - `--headed` — escalation for bot-managed sites: headed stealth real Chrome. - `--locale <tag>` — pin Accept-Language + context locale (geo-redirecting sites capture a different locale per run otherwise). `visual-diff` also: `--out <dir>`, `--sections a,b` (per-section screenshots). A bot-management challenge/blocked interstitial on either navigation fails LOUD with **exit 3** — it is never measured as the source. Escalate with `--headed`; if that is still blocked, the site needs crawl.mjs-class capture and the check cannot run headless. A plain (non-challenge) HTTP error on either side — e.g. a **404 build side, normal on aem.page before preview propagation** — is NOT fatal: the probe logs a loud warning, measures the error page, and the flags (BLANK RENDER / content asymmetry) carry the signal with **exit 0**. That is the probes' advisory contract: 0 = ran (flags advisory), 1 = probe error, 3 = bot challenge. ## The published-origin probes (#125) `content-diff` reconciles a prototype with its build; against a LIVE commerce origin its per-node findings were false, and the pixel gate passed a page whose every card was clipped (`../replica/reference/source-fidelity-gate.md` § The all-pages published-origin gate). Three probes ask the checkable questions; all load both sides in the same window-free real-Chrome tier and settle them the same way (`scripts/measure-live.mjs`). ```bash ORIGIN="https://www.example.com/<path>"; SERVED="https://main--repo--owner.aem.live/<path>" node stardust/scripts/diff/clip-probe.mjs "$SERVED" [--json clip.json] # D1: exit 2 on cut / hidden text or controls node stardust/scripts/diff/content-presence.mjs "$ORIGIN" "$SERVED" [--variable "<selO>=<selE>"] # D2: exit 2 on MISSING/HIDDEN link or heading node stardust/scripts/diff/unit-geometry.mjs "$ORIGIN" "$SERVED" --unit "<selO>=<selE>" --n 2 # D3: exit 2 on an element off / hidden / missing ``` Reading: a 🔴 clip group names the clipper (a fixed-height box with `overflow: hidden`) — fix that block's CSS, never the content. HIDDEN LINK = in the DOM but clipped (CSS); MISSING LINK = not served (encoder); CONTROL STATE = same control, another value; COUNT … = session-variable region, confirm by eye. The origin side fails loud on HTTP ≥ 400 (exit 4) and a bot challenge (exit 3). Traps: an infinite-scroll origin keeps loading under the settle — mark the region `--variable`; a live origin without `<main>` compares whole page against whole page (the scope line says so), header / footer left to the chrome crop gate unless `--chrome`; the count-phrase and "read more" heuristics are English word lists (`--count-words`, `--more-words`). ## The header contract (#132) Every probe above sees the header at rest (pointer parked, motion frozen), so it passes with every menu wrong; runs shipped boilerplate click dropdowns for hover mega menus, search and cart as plain links, a static list for a drill-down drawer. The header's behaviour is recorded from the source once and the build compared with it: ```bash node stardust/scripts/diff/chrome-explore.mjs "$ORIGIN" stardust/chrome/header-contract.json # 1440 + 390 node stardust/scripts/diff/chrome-explore.mjs "$SERVED" stardust/chrome/header-build.json node stardust/scripts/diff/chrome-compare.mjs stardust/chrome/header-contract.json stardust/chrome/header-build.json \ --profile replica --json stardust/chrome/header-parity.json # functional under redesign and reskin ``` The explorer hovers (desktop), clicks and keys every header control and records each opened state (links, headings, crop, `aria-expanded`, focus, scroll lock, motion, close paths), nested levels within `--max-states 400 --max-depth 4`, search typeahead and submit, and the header scrolled; its summary line sizes the work. The comparer exits 2 on a missing control or state (hover rebuilt as click included), panel links, keyboard, close paths or scroll lock; `replica` adds open-state crops (2 %), motion (max(80 ms, 25 %)) and scroll states. **Only the site owner clears a finding**: `stardust/chrome/header-decisions.json` (`{ decisions: [{ finding, decision, reason, by, at }] }`), never signed by an agent. It runs at extract `--prep` (the contract), on the foundation shell and in deploy Step 10, on the live host before handover (`done-check` `header_parity`), and in qa. Crops stay in `stardust/.work/chrome/`. ## Reading content-diff - 🔴 **MISSING CTA / HEADING / EYEBROW** — real dropped content. FIX. A missing eyebrow is most often a segmentation drop where the eyebrow precedes its heading; a missing CTA means the component never rendered the link. These are exactly what the pixel probe cannot see. - 🔴 **ROLE SWAP** — same text under a different role (body painted as eyebrow, eyebrow folded into a teaser). FIX the component's node segmentation. - 🔴 **MISSING PLACEHOLDER / ARIA-LABEL, MISSING ICON, ICON DIFF on an interactive element** (an input, a button, a link or inside one) — a dropped localized search placeholder, a share link without its aria-label or icon, a wrong flag in a locale link, an empty icon box. FIX. Outside interactive elements the same findings are 🟡. - 🟡 **MISSING TITLE** — always 🟡: a title tooltip is not read by most assistive tech and is commonly dropped by design. 🟡 **ICON MOVED** — the same icon (glyph code point / file name / svg signature) at another anchor, paired by identity and document order after the anchor passes (typically a text-less `<button>` host that anchors as `button#n`): the icon is present, CONFIRM its placement. 🟡 **ICON KIND** (glyph vs svg vs image — the pixel probe judges) and every **EXTRA**. - Every finding line names its root — `🔴 MISSING PLACEHOLDER [header]: …` — and the report prints one block per root (`root "main"`, `root "header"`, …; a root a side lacks is measured as empty there and the line says which side). - 🟡 **MISSING BODY / EXTRA** — body prose dropped, or build copy with no source. Usually a placeholder→real-copy rewrite. CONFIRM intended; don't blindly "fix". - 🟠 **FONT FORK** — matched lines whose rendered FACE differs (width probe, never `document.fonts.check`). `source X→sys` means the prototype named font X but never loaded it and fell back to system — the build self-hosting the intended fallback is then CORRECT, not a bug. All forked lines are grouped into one advisory. - **Known limitation — node-granularity JOIN/SPLIT reads as 🔴 (#87).** When the source renders one text run as N sibling nodes and the build renders the same text as ONE node (or vice versa — e.g. three fact chips vs one combined chip span), the diff currently reports MISSING + ROLE SWAP + EXTRA for what is a non-defect. Until concat-matching lands (a source node that is a substring of a same-region build node → 🟡 JOIN/SPLIT advisory), verify a 🔴 whose texts concatenate into an EXTRA finding's text before treating it as dropped content — confirmed-justified is a pass. **Pass bar:** visual red flags none/justified **AND** content-diff **0 structural 🔴** (🟡/🟠 confirmed intended). Re-run BOTH after each fix. ## Profiles `skills/diff/scripts/diff-profiles.mjs` holds them. A profile supplies the source/target **labels**, per-flag **remediation hints**, the **font-delta** threshold, the default content-root **selector**, and the **eyebrow** classifier thresholds. The engines carry no stack strings. - **`eds`** (default) — Edge Delivery / DA remediation language + the stardust `deploy` skill's finding numbers. - **`generic`** — neutral source/build language for any stack. Add a profile by copying `generic` in `diff-profiles.mjs` and editing `hints`. ## Shared engine + the in-loop sibling The structural probe's classifier + differ live in `skills/diff/scripts/content-inventory.mjs` (deploy imports its synced copy). They measure with the same instrument as two gates of the stardust `deploy` skill: `section-schema.mjs` (the pre-code ENCODE/DECODE contract, deploy #93) and `block-roundtrip.mjs` (the in-loop per-block gate, deploy #94 — the same inventory diff, run per block at authoring time against a local decorate() harness, no DA needed, exit-code gated). Run the in-loop gate while converting; run THIS skill's two probes as the final post-deploy proof. A defect first found here that the in-loop gate passed = the delivery pipeline reshaped the content in transport — fix the block's flattened-shape fallback, not the authoring. ## Workflow use Call both scripts in a validation phase and gate on the output, as deploy's Validate phase does on a served, decorated build (local harness or branch preview): fix visual-diff's STRETCHED/FLUSH-LEFT/SURFACE-GROUND/GAP flags (unless justified) and every content-diff 🔴, confirm 🟡/🟠, loop until both are clean.