/**
 * Harness detection for Pi and Pi-compatible hosts (such as OMP / oh-my-pi).
 */
export type PiHarness = "pi" | "omp" | "unknown";
/**
 * Set or clear an explicit harness override for tests.
 */
export declare function setHarnessOverrideForTesting(override: PiHarness | null): void;
/**
 * Record the active host ExtensionAPI instance passed to the extension factory.
 */
export declare function recordActiveExtensionApi(api: unknown): void;
/**
 * Clear any recorded ExtensionAPI reference.
 */
export declare function resetRecordedExtensionApi(): void;
/**
 * Determine the active Pi harness ("pi" | "omp" | "unknown").
 *
 * Runtime signal selection:
 * - Candidate 1: Host package resolution (`@oh-my-pi/pi-coding-agent` vs `@earendil-works/pi-coding-agent`).
 *   Rejected because resolving package names depends on node_modules layout. If `@oh-my-pi/pi-coding-agent`
 *   is present in node_modules (e.g. in a monorepo or test environment), resolving it succeeds even when the
 *   active host process is upstream Pi, producing a false positive on Pi.
 * - Candidate 2: `process.argv[1]`.
 *   Rejected because it is fragile and unreliable. Under test runners (bun test, vitest), CLI wrappers,
 *   symlinks, or programmatic embeds, `argv[1]` reflects the test runner or wrapper rather than the host.
 *   Furthermore, directory paths containing "omp" would produce false positives.
 * - Candidate 3: Fields on the `ExtensionAPI` object passed by the host.
 *   SELECTED. When an extension is loaded, the host creates and injects an `ExtensionAPI` instance into
 *   the extension factory (`ConcreteExtensionAPI` in OMP vs `createExtensionAPI` in upstream Pi).
 *   OMP's `ExtensionAPI` implementation (`extensibility/extensions/loader.ts:154-172` and `types.ts:1218-1231`)
 *   injects OMP-specific members that upstream Pi (`pi-mono/packages/coding-agent/src/core/extensions/loader.ts:280-360`
 *   and `types.ts:1252-1360`) has never exposed:
 *     - `api.arktype`: injected `@oh-my-pi/omptype` schema builder for extension tools (upstream Pi uses `@sinclair/typebox` and has no ArkType dependency).
 *     - `api.registerFileWriteFallback` / `api.registerFileDeleteFallback`: OMP's sandbox write/delete fallback handlers.
 *   Upstream Pi's `ExtensionAPI` (`pi-mono/packages/coding-agent/src/core/extensions/types.ts:1252-1500`) declares
 *   neither `arktype` nor `registerFileWriteFallback`, so inspecting those two cannot false-positive on Pi.
 *   NOT a signal: `api.events`. Upstream Pi's `ExtensionAPI` also carries `events: EventBus` (types.ts:1499,
 *   populated by `loader.ts:447`), so testing for it would classify every upstream Pi host as OMP and fold the
 *   guidance into descriptions that Pi already renders - the double-render this detector exists to prevent.
 *
 * @param api Optional ExtensionAPI instance. If omitted, the recorded API from extension initialization is checked,
 *            followed by global OMP environment indicators.
 */
export declare function detectPiHarness(api?: unknown): PiHarness;
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