/**
 * Per-instance platform pin — read-only, resolved at report time.
 *
 * One instance is owned by one platform. That ownership is not stored: it is
 * *derived* from `sessions.ndjson`, which already records `agent` on every
 * claim, renew and release event. Nothing here writes, and nothing on the write
 * path consults it.
 *
 * The separation is the whole point (design DD-1). If the pin fed
 * `resolveAgent`, every event after the first would record the first platform,
 * the log could never hold two distinct values, and `{ kind: 'skipped' }` would
 * be unreachable. Worse, `sync.ts` resolves a provider from the recorded
 * `agent`, so a Codex session on a claude-code-pinned instance would have its
 * rollout parsed by the claude-code provider and priced at Claude rates. A
 * confidently wrong figure is strictly worse than a missing one.
 *
 * Requirements: agent-portability/AC-59, AC-8, AC-31, AC-33, AC-34
 * Design: design.md A3
 *
 * @module
 */
/**
 * Who owns an instance's cost, as far as its session log can say.
 *
 * `unpinned` and `skipped` are deliberately different states. `unpinned` means
 * nobody could tell (no event ever named a platform) and reports as
 * unattributed, exactly as it does today. `skipped` means two platforms worked
 * the instance, so no single set of rates applies and the cost is *unmeasured* —
 * which must never render as `$0.00` (AC-9, AC-10, AC-28).
 */
export type PinVerdict = {
    kind: 'pinned';
    platform: string;
} | {
    kind: 'skipped';
    platforms: string[];
} | {
    kind: 'unpinned';
};
/**
 * Resolve which platform owns an instance's cost.
 *
 * Pure and uncached. `aidlc cost sync` walks every instance in one process, so a
 * memo keyed on anything less than the instance would hand the first instance's
 * answer to the second (AC-34) — the shape that made `resolveAgent`'s
 * `{root, home}` cache a hazard in the first draft of this design.
 *
 * A missing, empty, or wholly unparseable log yields `unpinned` rather than an
 * exception: `readSessionEvents` returns `[]` for all three (AC-33).
 */
export declare function resolvePin(projectRoot: string, instance: string): PinVerdict;
/** Human-readable reason for a skipped verdict — names both platforms (AC-9). */
export declare function skipReason(verdict: PinVerdict): string | null;
/**
 * How a verdict is labelled beside an instance name in `aidlc cost`.
 *
 * Extracted so the label is testable without spawning the CLI — this project has
 * enough subprocess tests already, and they are the ones that flake under load.
 *
 * Requirements: agent-portability/AC-56, agent-portability/AC-9
 */
export declare function pinLabel(verdict: PinVerdict): string;
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