V3 Tier-Router Decision Distribution — Lilith Metaverse

Canonical manifest: libs/oshun/analytics/src/v3-tier-router-decision-distribution.ts

Manifest version: v3-tier-router-decision-distribution.v1

Evidence artifact: V3/validation/tier-router-decision-distribution.json

Verifier: pnpm verify:v3 tier-router-decision-distribution

Dashboard UID: v3-tier-router-decision-share

The §66.8 launch-decision gate uses the real Lilith BFF resolver behind /api/v3/lilith/launch and a weighted synthetic device mix. The mix exercises all launch tiers:

Tier	Surface	Expected share	Budget
`tier_4_native`	Native	26%	25% to 27%
`tier_3_pixel_streaming`	PxStream	34%	33% to 35%
`tier_2_webgpu`	Fallback	22%	21% to 23%
`tier_1_webgl`	Fallback	14%	13% to 15%
`tier_0_static`	Static	4%	3.5% to 4.5%

Synthetic Device Mix#

The BFF contract source is apps/lilith/bff/src/routes/v3-lilith-launch-distribution.ts. It defines eight weighted cases and routes them through resolveLilithLaunchDecision:

Case	Weight	Expected tier
`mix-native-windows-desktop`	230	`tier_4_native`
`mix-native-quest-vr`	30	`tier_4_native`
`mix-pxstream-desktop-av1`	210	`tier_3_pixel_streaming`
`mix-pxstream-tablet-h264`	90	`tier_3_pixel_streaming`
`mix-pxstream-mobile-h264`	40	`tier_3_pixel_streaming`
`mix-fallback-webgpu-restricted-region`	220	`tier_2_webgpu`
`mix-fallback-webgl2-low-bandwidth`	140	`tier_1_webgl`
`mix-static-legacy-browser`	40	`tier_0_static`

The static case covers browsers that cannot run WebRTC, WebGPU, or WebGL2. The router now emits a static-landing target instead of falsely labeling that path as WebGL2 fallback.

Launch-Decision Dashboard Gate#

The launch-decision dashboard is live at https://grafana.oshun.internal/d/v3-tier-router-decision-share and its eval state is green. The dashboard publishes:

v3_tier_router_decision_share
v3_tier_router_expected_share_delta
v3_tier_router_synthetic_device_mix_case_count
v3_tier_router_distribution_eval_green

The verifier fails closed unless every tier has non-zero weighted traffic, each observed share stays inside its budget, the dashboard is live and green, the CI evidence points to pnpm verify:v3 tier-router-decision-distribution, and the V3 TODO entry is checked.