Default channel_monitor_mode to v1 (opt-in V2) so upgrades keep active
probes; existing explicit v2 rows are left alone via ON CONFLICT DO NOTHING
plus migration checksum compatibility for already-applied 195.
V2 first-enable backfill no longer compresses ticks to 5s or uses 24h
chunks. Each tick does recent overlap plus at most one historical chunk
with depth-based ceilings (2h/4h/6h), adaptive grow/shrink, and failure
backoff. Error request_id dedup is bounded by a 90-minute lookback so
ops_error_logs is not scanned for full history.
Also align hide_throughput parse default with privacy-preserving public
runtime (missing key → true).
Root cause: GetPublicSettingsForInjection used an inline struct that silently
drifted from dto.PublicSettings and omitted channel_monitor_enabled /
available_channels_enabled. On refresh window.__APP_CONFIG__ lacked these
keys, so cachedPublicSettings.available_channels_enabled resolved to
undefined and the opt-in sidebar entry (=== true) disappeared.
Backend: extract PublicSettingsInjectionPayload as a named type with all
feature-flag fields wired, and add a reflect-based drift test in the dto
package so forgetting a future flag fails CI instead of the browser.
Frontend: introduce utils/featureFlags.ts as the single registry for
public-settings-driven toggles, with explicit opt-in / opt-out modes that
encode the pre-load fallback. AppSidebar switches to makeSidebarFlag() so
adding a new switch only touches the registry.
IanShaw027