The Rail · Reference & analysis

RD.1 Watch surface integration

The phone is the only composer of watch Rail state.

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Authority and selection#

The phone is the only composer of watch Rail state. buildWatchRailTile accepts one explicitly selected ChannelManifest, re-parses it, requires surfaces.watch, and rejects the adult ring before producing a v10.watch-rail.1 payload. WatchCompanionBridge.pushRailTile atomically replaces or clears that one selection over the existing versioned companion transport.

Neither native companion accepts a manifest or invents channel state. Both cache only the last validated rail_tile, so the chosen channel remains glanceable while the phone is unreachable.

Content and behavior#

  • Rich tiles render the canonical header, state line, and optional glance metric.
  • Cold/text-only tiles render faces.spectator.textOnlyDegradation byte-for-byte; the TS, Swift, and Kotlin codecs reject a text-only payload whose state line differs from that field.
  • The Wear OS provider is the single Rail tile and the first screen in each native app is the same restrained, single-channel presence. Existing Today, Breath, Streak, and Settings screens remain.
  • A live-moment alert can enter the wire shape only when a real decision is granted at effective loudness 3 and names a live moment declared by the chosen manifest.
  • Native clients deduplicate alert ids and emit one gentle click/28 ms low-amplitude pulse. They remain silent when haptics are disabled or the phone-synced quiet-hours window is active.

Structural exclusions#

WatchRailRing is wellness | games in TypeScript, Swift, and Kotlin. There is no adult enum case. The canonical Zod schema also fixes alerts to granted: true and effectiveLoudness: 3; both native decoders repeat those checks at the trust boundary.

Verification notes#

  • Contract and bridge suites cover verbatim degradation, adult rejection, real grant-3 projection, malformed alert rejection, one-tile replacement/clear, and sync replay.
  • Swift and Kotlin parity suites cover codec round trips, non-grant rejection, haptic deduplication, and quiet-hours silence.
  • On the July 22 Linux host, the TypeScript contract/mobile checks run normally. Native suite setup remains host-constrained: Swift is not installed, and Gradle cannot install Android 36.1 until the Android SDK license is accepted. These are environment limitations, not suppressed test failures.
  • The full contracts suite also reports its existing common-manifest drift for portfolio-release-gates.ts; the focused V10 watch contract suite passes independently.