/**
 * Merge Byline's required Vite settings into a host application's own
 * `vite.config.ts`.
 *
 * The settings themselves are never written out by hand here. They are
 * extracted from the canonical template (`templates/host/vite.config.ts`) at
 * runtime, so that file stays the single source of truth and this module
 * cannot drift from it. `extractCanonicalPieces` is pinned by a contract test.
 *
 * Merging is deliberately conservative: every insertion must land in a key the
 * host config does not already define. If the config declares any of the keys
 * Byline owns, or is shaped in a way this module does not recognise, the caller
 * is told which pieces could not be placed and falls back to asking the user to
 * merge them by hand. A wrong merge is worse than no merge — it moves the
 * failure from install time, where the CLI can explain it, to a confusing
 * runtime or production-build failure.
 */
export interface CanonicalPieces {
    /** Source text of each module-level statement, keyed by declaration name. */
    statements: Map<string, string>;
    /** Source text of each `defineConfig` property, keyed by property name. */
    configProps: Map<string, string>;
    /** Source text of each `nitro()` option, keyed by property name. */
    nitroProps: Map<string, string>;
}
export interface MergePlan {
    /** Human-readable description of each edit, for the phase preview. */
    changes: string[];
    /** Pieces that could not be placed; the caller surfaces these for hand-merge. */
    unplaced: string[];
    /** Applies the plan and returns the edited source text. */
    apply(): string;
}
export type MergeAnalysis = {
    kind: 'canonical';
} | {
    kind: 'mergeable';
    plan: MergePlan;
} | {
    kind: 'unrecognized';
    reason: string;
};
/**
 * Pull the Byline-owned pieces out of the canonical template. Throws if the
 * template no longer contains an expected piece — that is a build-time bug in
 * Byline, not a problem with the user's config, and it must fail loudly.
 */
export declare function extractCanonicalPieces(canonicalSource: string): CanonicalPieces;
/**
 * Decide whether the host's config can take Byline's settings, and if so return
 * a plan that applies them.
 *
 * The async-hooks alias references `byline/async-hooks.browser.ts`, which the
 * scaffold phase writes. Wire runs *before* scaffold, so that file does not
 * exist yet at this point — we still emit the reference, exactly as the
 * canonical full-replace path does, because scaffold always follows wire in a
 * normal `init`. Gating on the file's presence would silently drop the alias
 * from every fresh install.
 */
export declare function analyzeUserConfig(userSource: string, canonical: CanonicalPieces): MergeAnalysis;
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