run402-mcp/dist/value-paging.js

MCP server for Run402 — full-stack backend infrastructure for AI agents: Postgres, auth, storage, serverless functions and atomic deploys. Paid with x402/MPP. Includes $0.03 image generation.

/**
 * How a `run` value is paged: by items, never by text lines.
 *
 * A value that fits the inline budget is returned whole. A larger one is paged
 * by the unit a reader thinks in:
 *
 *   - an array: its elements (`path: "$"`);
 *   - an object holding arrays: the elements of its largest top-level array,
 *     e.g. the `rows` of a SQL result (`path: "$.rows"`), with the object's
 *     other fields kept whole beside the window (`rest`);
 *   - any other object: its entries as `{ key, value }` (`path: "$entries"`);
 *   - a long string: its lines (`path: "$lines"`).
 *
 * The window is whole items only: as many leading items as fit the budget,
 * and always at least one, so a page never ends in the middle of a row.
 */
/** A value whose pretty-printed JSON fits in this many lines is returned whole. */
export const VALUE_INLINE_LINES = 200;
function prettyLines(value) {
    const text = JSON.stringify(value, null, 2);
    return text === undefined ? 1 : text.split("\n").length;
}
/** True when the whole value fits the inline budget. */
export function fitsInline(value, budget = VALUE_INLINE_LINES) {
    return prettyLines(value) <= budget;
}
/** The items a value pages by, and where they live. */
export function pageableItems(value) {
    if (Array.isArray(value))
        return { path: "$", items: value };
    if (value !== null && typeof value === "object") {
        const obj = value;
        let best = null;
        for (const [key, v] of Object.entries(obj)) {
            if (Array.isArray(v) && (best === null || v.length > obj[best].length))
                best = key;
        }
        if (best !== null && obj[best].length > 0) {
            const rest = {};
            for (const [key, v] of Object.entries(obj))
                if (key !== best)
                    rest[key] = v;
            return { path: `$.${best}`, items: obj[best], rest };
        }
        return { path: "$entries", items: Object.entries(obj).map(([key, v]) => ({ key, value: v })) };
    }
    if (typeof value === "string")
        return { path: "$lines", items: value.split("\n") };
    return { path: "$", items: [value] };
}
/** Page a value that does not fit inline: every item, and the leading window of whole items. */
export function pageValue(value, budget = VALUE_INLINE_LINES) {
    const { path, items, rest } = pageableItems(value);
    const restLines = rest ? prettyLines(rest) : 0;
    const window = [];
    let used = restLines + 2; // the brackets around the window
    for (const item of items) {
        const cost = prettyLines(item);
        if (window.length > 0 && used + cost > budget)
            break;
        window.push(item);
        used += cost;
    }
    return { path, items, window, ...(rest ? { rest } : {}) };
}
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