DevTools API Reference

Hand-written reference for everything @useoptimus/devtools exports today (packages/devtools/src/index.ts). See the DevTools adapter guide for usage and override precedence.

Overrides

resolveOverridesFromEnvironment(sources?)

interface OverrideSources {
  location?: Pick<Location, "search">;
  storage?: Pick<Storage, "getItem">;
  globalOverrides?: unknown; // e.g. window.__FEATURE_FLAGS_OVERRIDES__
}

function resolveOverridesFromEnvironment(
  sources?: OverrideSources, // defaults to reading window/localStorage
): Record<string, FlagOverride>;

Resolves with precedence query param (__ff_overrides) > localStorage (feature-flags:devtools:overrides) > injected global. Malformed JSON at any source is treated as absent, falling through to the next. Returns {} outside a browser (e.g. SSR) or when no source is present, instead of throwing.

applyOverridesToClient(client, overrides)

function applyOverridesToClient(client: FlagsClient, overrides: Record<string, FlagOverride>): void;

One-line convenience for client.setOverrides(overrides). FlagOverride comes from @useoptimus/core; overridden reads always resolve with reason: "override" and never fire onEvaluate exposure handlers.

Debug panel

FeatureFlagsPanelElement / registerFeatureFlagsPanel

class FeatureFlagsPanelElement extends HTMLElement {
  client: FlagsClient | undefined; // settable property, not an HTML attribute
}

function registerFeatureFlagsPanel(): void; // idempotent

registerFeatureFlagsPanel() defines the <feature-flags-panel> custom element (a no-op if already defined). Setting .client subscribes to client.subscribe() and renders one row per registered flag — a raw-JSON value input, an optional variant-key input, and Apply/Clear buttons that call client.setOverrides()/client.clearOverrides(). v1 scope is deliberately minimal: no type-aware widgets (no boolean toggle, no variant dropdown).