import type { AgentMessage } from "../internal/harness.js";
import type { Model } from "../internal/llm.js";
/**
 * Last-resort, in-task context trim. Proper compaction (LLM summary) runs *between* tasks;
 * this prevents a single task whose internal tool-loop balloons from overflowing the window.
 *
 * Keeps all summary messages (compaction/branch) and the most recent messages that fit the
 * budget, dropping older regular messages at a safe boundary (never starting on an orphan
 * toolResult). Returns the original array when already within budget.
 *
 * design/123 D3 (codex-B1 = fable-M5) — anchored accounting: when `anchoredTotalTokens`
 * (= `estimateContextTokens(messages, charsPerToken).tokens` for the SAME array) is provided, the
 * trigger gate and the internal bookkeeping start from the usage-anchored value instead of the
 * structural sum (which underestimates code/CJK and lets over-window requests through). Dropping a
 * message AFTER the usage anchor reduces the accounted total by its structural estimate; dropping a
 * message AT/BEFORE the anchor reduces it by ZERO (the anchor usage was billed with that content —
 * a request-view drop only pays off on the NEXT request), so the trim keeps cutting deeper until
 * the anchored total meets the budget or only the minimal tail is left. Absent ⇒ legacy structural
 * behavior, byte-identical. `charsPerToken` (design/123 D2): structural coefficient, default 4.
 */
export declare function trimToBudget(messages: AgentMessage[], budgetTokens: number, anchoredTotalTokens?: number, charsPerToken?: number): AgentMessage[];
/**
 * design/123 D3 belt (invariant-level, live-caught 16k 400s): the FINAL request view must never
 * contain a toolResult whose tool-call assistant is absent — strict gateways hard-400 on it
 * ("Messages with role 'tool' must be a response to a preceding message with 'tool_calls'"). Every
 * individual producer is turn-aligned (findCutPoint never cuts on a toolResult; trimToBudget
 * turn-aligns its floor), but NO pipeline combination may ship an orphan, so the prepare-task
 * context hook sweeps its output through this last. Deterministic ⇒ byte-stable per request ⇒
 * prefix-cache safe. Returns the SAME array when clean (zero-cost fast path); `dropped` carries a
 * diagnostic per removed orphan (toolCallId + neighbor roles) for onError attribution.
 */
export declare function dropOrphanToolResults(messages: AgentMessage[]): {
    messages: AgentMessage[];
    dropped: Array<{
        toolCallId: string;
        index: number;
        prevRole: string;
        nextRole: string;
    }>;
};
/** Budget the in-task guard targets for a model. */
export declare function guardBudget(model: Model): number;
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