Manifest position 513 · CrUX rank bucket 1000
https://m.youtube.com
Coverage complete
Coverage-complete audit of the public first-time mobile entry, watch, search and error-route surfaces. Authenticated and post-consent playback/account journeys were not covered.
Attempts
1 / 3
Judged checks
58 / 58
Blocked
0
Not run
0
This report has no published overall score. Blocked and not-run checks are not passes. A coverage-complete report means every check has a judged outcome; it does not mean every check passed.
All 58 atomic check outcomes
| Principle / check | Status | Confidence | Evidence or reason |
|---|---|---|---|
respect-user-preferencesrespects-color-scheme | issues | high | The prefers-color-scheme:dark screenshot is pixel-identical in appearance and file size (96,160 bytes) to the light capture, remaining a bright white full-screen surface even though matchMedia reports dark=true. F01 high: The mandatory consent surface ignores the user’s dark colour preference. |
respect-user-preferencesrespects-reduced-motion | pass | high | Preference probe reports reduced=true and zero active animations on the consent surface. |
respect-user-preferencesrespects-contrast | pass | high | High-contrast screenshot preserves readable text, icons, borders, and controls without clipping. |
implement-natural-interactionsview-transitions | pass | high | The audited initial consent state does not perform an abrupt in-document state swap; navigation uses normal document navigation. |
implement-natural-interactionsscroll-driven-animations | not-applicable | high | No scroll-linked storytelling, parallax, carousel motion, or entry/exit reveal is present on the audited consent surface. |
implement-natural-interactionsphysical-gestures | not-applicable | high | No gesture-driven removal, pull-to-refresh replacement, or custom swipe interaction is exposed on the audited surface. |
provide-guided-navigationscroll-state-aware-chrome | pass | high | The consent document scrolls within a stable single-column surface without JS-driven sticky chrome obscuring content. |
provide-guided-navigationanchored-positioning | not-applicable | high | No tooltip, popover, or edge-positioned menu is opened on the consent path. |
provide-guided-navigationdirects-attention | pass | high | Heading, explanatory sequence, icon bullets, and equal decision controls provide a clear reading and decision order. |
maximize-content-reduce-noiseno-intrusive-interruptions | issues | high | Mobile screenshots on home, search, watch, and an error route show only the consent document; Reject all and Accept all are below the initial 844px viewport after several paragraphs. F02 high: A long, full-viewport consent interstitial hides all YouTube content before first use. |
maximize-content-reduce-noisesemantic-dismissible-primitives | pass | high | The consent surface is exposed as a modal/dialog-like custom element, traps focus, and provides explicit Reject, Accept, and More options actions. |
maximize-content-reduce-noisereduced-chrome | pass | high | The screenshot shows a restrained single-column consent layout with little decorative application chrome. |
adapt-to-the-form-factorresponsive-no-horizontal-scroll | pass | high | Layout at 390×844 reports scrollWidth=clientWidth=390 and horizontalOverflowPx=0 with viewport meta present. |
adapt-to-the-form-factorcomponent-level-responsiveness | pass | medium | Mobile and desktop captures reflow the consent layout to the available viewport without fixed desktop-width overflow. |
adapt-to-the-form-factorinput-modality-aware | issues | high | The target probe measured Guide, Search, Settings and icon controls at 24×24 CSS px, below the recommended 44×44 mobile target, although consent decision buttons are 40px high and keyboard focus remains visible. F15 medium: Several mobile header controls expose undersized touch targets. |
support-core-task-successclear-purpose-and-primary-action | pass | high | The heading states “Before you continue to YouTube” and the copy explicitly explains Reject all, Accept all, and More options. |
support-core-task-successprimary-flow-completion | pass | high | The consent surface exposes equally labelled Reject all and Accept all completion actions plus More options, without hidden required fields. |
support-core-task-successclear-system-state-and-recovery | pass | high | The modal clearly states why content is paused and offers rejection, acceptance, settings, privacy, terms, and sign-in paths. |
be-fast-and-stablegood-core-web-vitals | issues | high | Lighthouse measured FCP 4.9s, LCP 6.7s, TBT 256ms and performance 0.59; the independent trace measured LCP 3.94s and 286ms total blocking time. F03 high: The first-time mobile experience paints too slowly. |
be-fast-and-stablevisual-stability | pass | high | Layout observer measured CLS 0.000143 and Lighthouse measured 0.000714, both well inside the good threshold. |
be-fast-and-stableefficient-main-thread | issues | high | The trace recorded five long tasks, including 267ms, with 285.88ms total blocking time; layout observation independently found a 413ms task. F04 medium: Startup JavaScript blocks the main thread. |
be-fast-and-stableefficient-resource-delivery | issues | high | Lighthouse flagged render-blocking requests with an estimated 210ms saving and a long network dependency tree; HAR transferred 4.05MB over 146 requests before consent completion. F16 high: Critical delivery is burdened by render-blocking and oversized startup resources. |
be-fast-and-stabletrim-unused-and-duplicate-code | issues | high | HAR captured 146 requests and 4,047,594 transferred bytes, including 3,031,432 script bytes. Lighthouse estimated 639KiB unused JavaScript and 153KiB unused CSS. F05 high: The consent path ships a disproportionate application payload before the user can access content. |
be-inclusivenames-roles-labels | issues | high | Lighthouse accessibility 0.85 found the visible “en-GB” button name does not match aria-label “Language: English (United Kingdom)”, and the underlying language select has no label or accessible name. F06 high: The consent language control has broken accessible naming. |
be-inclusivesufficient-contrast | issues | high | Lighthouse measured the Search YouTube text at 3.06:1 (#717171 on #272727), below the required 4.5:1 for 16px normal text; links in text also rely on colour alone. F07 high: Some primary UI text fails minimum colour contrast. |
be-inclusivestructure-and-focus | pass | high | Consent surface has a clear heading and keyboard focus-visible styles; Lighthouse did not flag focus order or landmark failures. |
be-inclusivelegible-text | pass | high | Mobile screenshot shows comfortable 16px body text, adequate line spacing, and no clipped wrapping at 390px. |
be-inclusivezoom-reflow-targets-and-media | issues | high | Lighthouse found user-scalable=no / a restrictive maximum-scale in the viewport meta. The focus/target probe also measured several header controls at only 24×24 CSS px. F08 high: The viewport configuration disables user zoom. |
follow-best-practicesno-console-errors | issues | high | Lighthouse captured an HTTP 400 from /youtubei/v1/feedback?prettyPrint=false and scored the console-errors audit 0. F09 medium: The initial page load logs a failed application request. |
follow-best-practicessound-document-and-assets | pass | high | Lighthouse passes doctype, charset, image aspect ratio, and deprecated API audits. |
follow-best-practicesbrowser-platform-hygiene | issues | high | Lighthouse found missing source maps for large first-party JavaScript, Inspector issues, and a BFCache failure caused by cache-control:no-store plus an HTTP-only cookie mutation. F10 medium: The page misses platform diagnostics and navigation-restoration opportunities. |
be-discoverabletitle-and-description | pass | high | Home has title YouTube and a meta description; the watch page has a unique descriptive title and description. |
be-discoverablecrawlable-and-mobile-friendly | issues | high | Discoverability captures classified both home and watch as JavaScript shells with only 6% rendered-word coverage in raw HTML. The crawler screenshots show skeleton cards rather than the rendered labels and page content. F11 high: Non-JavaScript crawlers receive only a small fraction of the visible content. |
be-discoverablecanonical-and-indexing-signals | pass | high | Watch response is HTTP 200 with canonical https://www.youtube.com/watch?v=uT7MVcCQ4rw; robots.txt is available and does not block watch URLs. |
be-discoverablestructured-and-shareable-metadata | pass | high | Watch page exposes canonical metadata, 18 Open Graph entries and two JSON-LD blocks that match the visible video title and thumbnail. |
be-private-and-securesecure-transport-and-headers | pass | high | HTTPS, HSTS, nosniff, SAMEORIGIN, CSP and Secure cookies are present; no mixed-content or sensitive-secret signal was found. |
be-private-and-securedata-minimisation-and-third-parties | pass | high | Tracker primitive found no known tracker domains before consent; SameSite cookies are first-party and public Google API keys are expected client configuration, not secrets. |
be-private-and-securein-context-permissions-and-modern-auth | pass | medium | No geolocation/notification permission prompt occurs on load; a sign-in action is user initiated. Authentication internals were not required to judge prompt timing on this path. |
be-private-and-securedefensive-browser-policies | issues | high | Headers include HSTS, nosniff, SAMEORIGIN and Trusted Types, but CSP still permits unsafe-eval/unsafe-inline and Referrer-Policy is absent. F12 medium: The security policy has avoidable browser-defense gaps. |
be-resilientprogressive-enhancement | issues | high | Raw HTML comparison found only 6% content-word coverage on the watch page; the no-JavaScript screenshot is largely a skeleton despite the server response containing title metadata. F13 high: Core content is not progressively available without JavaScript. |
be-resilientresilient-runtime-behaviour | pass | high | The consent overlay remains within the viewport, scrolls without horizontal clipping, preserves controls, and presents stable state. |
be-resilientoffline-and-installable | not-applicable | high | YouTube playback and search are intrinsically network-dependent; an install/offline playback promise was not part of the unauthenticated web surface audited. |
be-resilientnetwork-and-http-failure-states | pass | high | A nonexistent route still renders a stable recoverable consent entry rather than a blank screen; users retain navigation/sign-in/privacy controls. |
be-internationalisedlang-dir-and-logical-properties | pass | high | html lang is en-GB and a prominent language picker offers many locales; the mobile layout preserves reading order. |
be-internationalisedlocale-aware-data | not-applicable | high | The audited consent surface exposes no dates, numbers, currencies, durations, or calendars requiring locale formatting. |
be-internationalisedtime-zone-correctness | not-applicable | high | The audited surface exposes no scheduled or time-zone-sensitive event data. |
be-trustworthyno-dark-patterns | pass | high | Reject all and Accept all use equal button treatment and More options is explicit; no preselected checkbox, confirmshaming, or disguised advert appears. |
be-trustworthyhumane-error-handling | not-applicable | high | No editable form or validation flow appears on the audited unauthenticated consent surface. |
be-trustworthytrustworthy-input-assistance | not-applicable | high | No address, payment, sign-in, sign-up, or other editable input appears on the audited consent surface. |
be-trustworthysafe-commercial-and-account-flows | not-applicable | high | No checkout, subscription, authenticated account-management, or sensitive-action flow was entered; the visible consent choice was assessed under no-dark-patterns. |
be-sustainableoptimised-assets | pass | high | Images primitive found no oversized or legacy raster payload on the consent path; HAR image transfer was only 127 bytes. |
be-sustainableno-wasteful-work | pass | high | No ongoing animation is active under reduced motion; repeated scrolling did not grow heap, though pre-consent request volume is separately flagged. |
be-sustainablethird-party-and-media-budget | issues | high | The first-load HAR transferred 4.05MB across 146 requests before content access, including 3.03MB script and 100 XHR/fetch requests. Host classification overstates third parties because m.youtube.com redirects to www.youtube.com, but the total work remains large. F14 medium: The pre-consent network and script budget is disproportionate to the visible consent task. |
be-agent-readystructured-agent-capabilities | not-applicable | high | The public watch/content surface provides metadata but exposes no safe transactional capability that requires WebMCP tools; emerging agent actions are out of this run’s scope. |
be-agent-readyon-device-inference | not-applicable | high | No summarisation or language-model task is offered in the audited unauthenticated surface, so on-device inference has no applicable user-facing task. |
be-memory-efficientno-leak-under-repeated-interaction | pass | high | After ten top-to-bottom scroll cycles, retained self size fell from 70,528,211 to 70,480,731 bytes; node count changed by only 2,143 (0.15%). |
be-memory-efficientbounded-footprint | pass | high | Heap summary reports about 70.5MB retained self size for the loaded YouTube consent/application shell; high but bounded for this media application. |
be-memory-efficientno-detached-dom-or-unbounded-listeners | pass | high | Neither heap summary contains Detached* constructors and the repeated-scroll comparison shows no unbounded retained growth. |
Provenance
Canonical report: results/atomic/reports/0513-m_youtube_com.json
Report SHA-256: 0e1607d596e19cebe6704b9ef0f061a34365b5abd593018664619ac0bd0a662c
Local retained report: runs/2026-07-17T17-27-24-856Z/atomic-reports/m_youtube_com/2026-07-21T07-34-49-272Z/report.json
Local evidence root: runs/2026-07-17T17-27-24-856Z/atomic-reports/m_youtube_com/2026-07-21T07-34-49-272Z
Catalog SHA-256: sha256:78ccfdb2d483f4c57d9dafed80fd86c6265585a56457c8dcfddc254b80fb44d7
Raw screenshots, HARs, traces, heaps, and other browser artifacts are retained at the local evidence root and intentionally are not committed. Artifact paths in the canonical report are relative to that root.