export declare const VALID_SOURCES: readonly ["Nano Banana", "Seedream 4.0", "Seedream 4.5", "OpenAI", "Flux 1.1 Pro", "Flux 2 Pro", "Google Imagen 4", "GPT Image 2", "Grok Imagine", "Wan 2.7"];
export type DesignStyle = 'photoreal' | 'vector' | 'abstract' | 'auto';
/** Normalize a caller-supplied `source` to its canonical VALID_SOURCES spelling, case-insensitively.
 *  The platform's source-name match is case-insensitive too, but its slow-model async routing is
 *  case-SENSITIVE — so a near-miss like "SeeDream 4.5" would run synchronously and a wrong name like
 *  "Flux 1.1" would 500 there. Normalizing here forwards the exact canonical name, or throws a clear
 *  bad_request (non-fallbackable) listing the valid sources, instead of a confusing downstream
 *  failure (ApparelHub-AI/apparelhub-mcp#70). */
export declare function normalizeSource(source: string): string;
export declare const EDIT_CAPABLE_SOURCES: Set<string>;
/** Pick a source. Nano Banana is the best all-rounder (photoreal + text + abstract). OpenAI is
 *  deliberately NEVER preferred (operator directive: it's the least-preferred model — its account
 *  is a shared billing surface and it only wins on nothing today). The user can always override
 *  with an explicit source. */
export declare function pickSource(_opts?: {
    style?: DesignStyle;
    hasText?: boolean;
}): string;
/** Build the ordered, de-duplicated list of sources to try for one generation. When an explicit
 *  `source` is given it goes FIRST, then the appropriate ladder is appended (deduped). When
 *  `edit` is true the list is restricted to the edit-capable sources (img2img); a text-to-image-only
 *  source (only Google Imagen 4) can never be a valid edit fallback. */
export declare function fallbackLadder(opts?: {
    style?: DesignStyle;
    source?: string;
    edit?: boolean;
}): string[];
/** TRUE for per-model / transient failures that warrant trying a different model. Validation
 *  (bad_request/unprocessable), auth (auth_required), forbidden/membership-quota (forbidden),
 *  not_found, AND `platform_rate_limited` (ApparelHub's own per-key throttle — model-independent)
 *  MUST return FALSE so they surface immediately. A `generation_failed` is fallbackable ONLY when
 *  its message is rate-limit-shaped (legacy heuristic; structured async failures now arrive as
 *  the precise `model_rate_limited` code instead). */
export declare function isFallbackableError(err: unknown): boolean;
/** The terminal code for "every model refused this on content grounds".
 *
 *  This is the ONLY signal that abandoning a design is legitimate. A single block never is —
 *  that was the behaviour being corrected. Kept distinct from `content_blocked` so an agent can
 *  tell "one model said no" from "all ten did". */
export declare const CONTENT_BLOCKED_ALL_MODELS = "content_blocked_all_models";
/** TRUE when a provider refused on content/copyright grounds (platform code `content_blocked`,
 *  normalised across every provider by the platform side of this work). */
export declare function isContentBlockError(err: unknown): boolean;
/** Every model worth trying after a content block, ordered provider-diverse, minus `exclude`.
 *
 *  Round-robin across providers means the first few rungs each land on a DIFFERENT guard, which is
 *  where nearly all the value is: if a different guard is going to render this prompt, it renders
 *  on rung 2, not rung 7. Siblings on an already-refused host come later, once diversity is spent.
 *
 *  `edit` restricts to the edit-capable set — a text-to-image-only model can never be a valid edit
 *  fallback, and offering one would just spend a rung on a guaranteed 400. */
export declare function contentBlockSweep(opts?: {
    edit?: boolean;
    exclude?: Iterable<string>;
}): string[];
/** The provider a source rides, for honest reporting. */
export declare function providerOf(source: string): string | undefined;
/** Lesson 9b: never ask a model for a "transparent background" — request a solid green one and
 *  key it out afterward. Idempotent (skips if the prompt already asks for a green background).
 *
 *  ⚠️ Only call this when the design will actually be keyed. Appending it for an
 *  all-over print produced a green-framed image that nothing then keyed out (#765). */
export declare function augmentPromptForTransparency(prompt: string): string;
/** TRUE when a provider rejected the request for prompt LENGTH.
 *
 *  Distinct from a rate limit or a transient 5xx: retrying the same prompt on the
 *  same model can never succeed, but the same prompt on a model with a longer limit
 *  will. So it IS fallbackable — and it must never be reported to the agent as "the
 *  model is rate limiting" or "the model is down", because neither is true and both
 *  send the agent to the wrong remedy (#766). */
export declare function isPromptTooLongError(err: unknown): boolean;
/** Build an img2img edit prompt from a change description + a list of aspects to preserve. */
export declare function buildIterationPrompt(change: string, preserve: string[]): string;