Status: Phase 3 — first cut shipped (this stub names the contract; the four-query plumbing already exists in src/app/globals.css). Deepens in Phase 5 with per-token fallback resolution map and per-primitive citations.

Statement

Epoch Shield honors four platform-level accessibility media queries as a single contract. They are not optional polish; they are the cheapest, highest-leverage user-agency hooks the browser gives us. Every primitive that ships a frosted surface, gradient, animation, or focus affordance MUST resolve its appearance under each query.

Query	Contract
`prefers-reduced-motion: reduce`	Signature transitions degrade to a calmer equivalent per A-2. Decorative animations (`pulse-glow`, `shimmer`, `float`, etc.) collapse to static. Loading indicators may persist if they encode state, but their motion budget shrinks.
`prefers-reduced-transparency: reduce`	Materials (F-8 `.material-regular`, `.material-thin`) collapse `backdrop-filter` to `none` and substitute the underlying token-backed solid surface (`var(--surface-1)`). The ambient `body::before` gradient glow and any decorative chroma overlays are suppressed.
`prefers-contrast: more`	Focus ring outline thickens from 2px → 3px per DEC-0019. Semantic ink (`--ink-1`, `--ink-2`, `--ink-3`) saturates toward the canonical hex (not toward black/white — saturation preserves meaning). Gradient text degrades to flat brand ink. Inactive-row affordances gain a 1px border.
`forced-colors: active`	Focus ring cedes to the OS highlight color per DEC-0019. Gradient backgrounds collapse to `Canvas` / `CanvasText`. Semantic-color chips retain their meaning by mapping to `Mark` / `MarkText` (warning), `LinkText` (interactive), `GrayText` (disabled). The brand logo and `body::before` glow are hidden — they carry no information.

Why

Each query represents a user who has explicitly told their OS what they need. Ignoring them is not a "wasn't tested" failure — it is an active decision to override the user's stated preference. The four queries cover the four most common accommodation domains: vestibular (motion), cognitive load (transparency), low vision (contrast), and high-contrast OS modes including Windows High Contrast (forced-colors).

The audit (Design/0000-hig-diagnostic.md §2.4, §3.2) flagged this as the single largest a11y gap: only prefers-reduced-motion had any plumbing, and even that was partial (the three signature transitions honored it; the decorative-animation pool did not). The other three queries had zero hooks anywhere in the codebase. This stub closes the contract.

How

The four queries are wired at the globals.css layer so primitives inherit the behavior without per-component plumbing:

prefers-reduced-motion — three blocks at globals.css#L579, L600, L624 cover signature transitions (route crossfade, shield pulse, message-in spring). A fourth block at #L957 provides the catch-all animation-duration: 0.01ms !important for everything else.
prefers-reduced-transparency — two blocks at globals.css#L256, L711 degrade materials (per F-8) and the body-level glow.
prefers-contrast: more — one block at globals.css#L217 thickens the focus ring per DEC-0019 and saturates semantic ink.
forced-colors: active — handled inline at the focus-ring site per DEC-0019, and at the body::before ornamental layer (suppressed entirely).

Components that ship their own animation, gradient, or material must not override these blocks. If a primitive needs a per-component fallback (e.g. a custom keyframe that would otherwise run under reduced-motion), it MUST add its own @media (prefers-reduced-motion: reduce) block citing this principle.

Cross-references

A-2 — reduced-motion fallback per motion token. A-2 is the per-token policy; A-4 is the platform-query contract that A-2 plugs into.
F-8 — materials taxonomy. F-8 specifies the materials; A-4 names the queries under which they degrade.
DEC-0019 — focus-ring contract. The contrast + forced-colors hooks live there.

Out of scope (Phase 5)

Per-token fallback resolution map (every token in tokens.json documents its appearance under each of the four queries).
Storybook a11y addon coverage that exercises each query in the snapshot matrix.
Per-primitive citation of which queries each Footer/Sheet/Popover/Modal/Drawer/Toast honors.

Stop conditions

If any decorative animation can be shown to fire under prefers-reduced-motion: reduce, file as an A-4 violation (not a one-off bug).
If prefers-reduced-transparency: reduce ever produces an unreadable surface (contrast collapse on the substituted solid), raise --surface-1 opacity in that context — never revert the degradation.
If forced-colors: active strips a primitive of meaning (e.g. severity chip color encoding is lost), add a border + glyph fallback. Never reinstate the gradient.