/** A phase number claimed somewhere CADENCE can observe. */
export interface Occupancy {
    /** The leading numeric token of the phase dir name (`30-auth` → 30). */
    number: number;
    /** The full phase-directory name (e.g. `30-auth`), not just the parsed number. */
    name: string;
    /** Where the claim was observed. `local` is this worktree's own `.cadence/phases/`. */
    source: 'local' | 'sibling' | 'upstream';
    /** Human-readable origin — a worktree path or `origin/<ref>`. */
    location: string;
}
export interface CollisionResult {
    collides: boolean;
    conflicts: Occupancy[];
    /** `max(target, ...observed) + 1` — monotonic, not lowest-gap. */
    nextFree: number;
}
/**
 * The collision key is the **leading numeric token** of a phase dir name, NOT
 * the full slug — so `30-auth` and `30-cache` both normalize to `30` and
 * collide. Non-numeric / unparseable names return `null` and are ignored.
 */
export declare function phaseNumber(dirName: string): number | null;
/**
 * Detect whether `target` collides with any observed occupancy. A collision is
 * pure numeric equality, ignoring any source in `opts.excludeSources` — the
 * settle backstop passes `['local']` to drop self (the active phase lives in the
 * local worktree, so a cross-worktree collision is sibling/upstream only).
 * Exclusion is by SOURCE, not number: self and a genuine sibling collision share
 * the same number, so a number-based exclusion would also hide the sibling.
 * `nextFree` is `max(target, ...all observed numbers) + 1` — every observed
 * number counts toward the next free slot, even excluded-source ones.
 *
 * A further, narrower exemption (issue #129) layers on top of `excludeSources`:
 * an `upstream` occupancy at `target` is NOT a conflict when its `name` exactly
 * matches a `local` occupancy's `name` at the same number — this is the
 * worktree's own phase directory, already pushed to `origin/<ref>`, showing up
 * as if it were a foreign upstream claim. An `upstream` occupancy whose `name`
 * differs (same number, different slug) is still a genuine foreign conflict.
 * `sibling` occupancies are deliberately NOT exempted by this — only `upstream`.
 */
export declare function detectPhaseCollision(target: number, occupancies: readonly Occupancy[], opts?: {
    excludeSources?: Occupancy['source'][];
}): CollisionResult;
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