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import type { GitObjectType } from "@/worker/git/core";
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import { objTypeCode, encodeObjHeader, concatChunks } from "@/worker/git/core";
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import { asBufferSource, deflate } from "@/worker/common";
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/**
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 * Builds a PACKv2 file from a list of thick objects (no deltas expected here).
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 * Shared between upload-pack assembly and DO hydration segment builder.
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 */
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export async function buildPackV2(
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  objs: { type: GitObjectType; payload: Uint8Array }[]
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): Promise<Uint8Array> {
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  // Header: 'PACK' + version (2) + number of objects (big-endian)
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  const hdr = new Uint8Array(12);
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  hdr.set(new TextEncoder().encode("PACK"), 0);
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  const dv = new DataView(hdr.buffer);
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  dv.setUint32(4, 2); // version 2
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  dv.setUint32(8, objs.length);
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  const parts: Uint8Array[] = [hdr];
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  for (const o of objs) {
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    const typeCode = objTypeCode(o.type);
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    const head = encodeObjHeader(typeCode, o.payload.byteLength);
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    parts.push(head);
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    const comp = await deflate(o.payload);
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    parts.push(comp);
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  }
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  const body = concatChunks(parts);
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  const sha = new Uint8Array(await crypto.subtle.digest("SHA-1", asBufferSource(body)));
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  const out = new Uint8Array(body.length + 20);
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  out.set(body, 0);
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  out.set(sha, body.length);
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  return out;
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}