Rebuild local Blender WASM environment and recovery evidence

tools/web/build-m12-git-snapshot.mjs

@@ -0,0 +1,107 @@
+import assert from "node:assert/strict";
+import crypto from "node:crypto";
+import fs from "node:fs";
+import path from "node:path";
+import { execFileSync } from "node:child_process";
+import { fileURLToPath } from "node:url";
+
+const root = path.resolve(path.dirname(fileURLToPath(import.meta.url)), "../..");
+const driftPath = path.join(root, "tests/golden/corrective/rehydration/M12-manifest-sha-drift.json");
+const outputArgumentIndex = process.argv.indexOf("--out");
+const outputRoot = path.resolve(root, outputArgumentIndex >= 0 ? process.argv[outputArgumentIndex + 1] : "tests/golden/corrective/rehydration/M12-git-history-snapshot");
+const filesRoot = path.join(outputRoot, "files");
+const drift = JSON.parse(fs.readFileSync(driftPath, "utf8"));
+const sha256 = (bytes) => crypto.createHash("sha256").update(bytes).digest("hex");
+const run = (args) => execFileSync("git", args, { cwd: root, encoding: "utf8", maxBuffer: 32 * 1024 * 1024 });
+const uniqueEntries = new Map();
+for (const entry of drift.entries) {
+  const key = `${entry.path}\0${entry.originalSha256}`;
+  if (!uniqueEntries.has(key)) uniqueEntries.set(key, entry);
+}
+
+function historicalBlob(pathname, expectedSha) {
+  let objectListing = "";
+  try {
+    objectListing = run(["rev-list", "--objects", "--all", "--", pathname]);
+  } catch {
+    return null;
+  }
+  const candidates = [...new Set(objectListing.split("\n").map((line) => line.split(" ")[0]).filter((id) => /^[0-9a-f]{40}$/u.test(id)))];
+  for (const blob of candidates) {
+    let type;
+    try {
+      type = run(["cat-file", "-t", blob]).trim();
+    } catch {
+      continue;
+    }
+    if (type !== "blob") continue;
+    const bytes = execFileSync("git", ["cat-file", "blob", blob], { cwd: root, maxBuffer: 64 * 1024 * 1024 });
+    if (sha256(bytes) !== expectedSha) continue;
+    let commits = [];
+    try {
+      commits = run(["log", "--all", "--format=%H", "--", pathname]).trim().split("\n").filter(Boolean);
+    } catch {
+      commits = [];
+    }
+    const commit = commits.find((candidate) => {
+      try {
+        return run(["rev-parse", `${candidate}:${pathname}`]).trim() === blob;
+      } catch {
+        return false;
+      }
+    }) ?? null;
+    return { blob, commit, bytes };
+  }
+  return null;
+}
+
+const matched = [];
+const unresolved = [];
+const pathPairCounts = new Map();
+for (const entry of uniqueEntries.values()) pathPairCounts.set(entry.path, (pathPairCounts.get(entry.path) ?? 0) + 1);
+for (const entry of uniqueEntries.values()) {
+  const pathname = entry.path;
+  const result = historicalBlob(pathname, entry.originalSha256);
+  if (!result) {
+    unresolved.push({ path: pathname, originalSha256: entry.originalSha256, reason: "exact SHA-256 content was not found in Git history" });
+    continue;
+  }
+  const suffix = (pathPairCounts.get(pathname) ?? 0) > 1 ? `.${entry.originalSha256.slice(0, 16)}` : "";
+  const snapshotPath = path.join("files", `${pathname}${suffix}`);
+  const destination = path.join(outputRoot, snapshotPath);
+  fs.mkdirSync(path.dirname(destination), { recursive: true });
+  fs.writeFileSync(destination, result.bytes);
+  matched.push({
+    path: pathname,
+    snapshotPath,
+    sha256: entry.originalSha256,
+    bytes: result.bytes.length,
+    gitBlob: result.blob,
+    gitCommit: result.commit,
+  });
+}
+
+const repository = run(["remote", "get-url", "origin"]).trim();
+const head = run(["rev-parse", "HEAD"]).trim();
+const manifest = {
+  schemaVersion: 1,
+  mode: "IMMUTABLE_REPOSITORY",
+  authorized: true,
+  source: {
+    kind: "GIT_HISTORY",
+    repository,
+    head,
+    selection: "exact original SHA-256 content match; current worktree is never read",
+  },
+  coverage: {
+    requestedPaths: new Set([...uniqueEntries.values()].map((entry) => entry.path)).size,
+    requestedPairs: uniqueEntries.size,
+    matchedPaths: matched.length,
+    unmatchedPaths: unresolved.length,
+    unresolved,
+  },
+  files: matched.sort((a, b) => a.path.localeCompare(b.path)),
+};
+fs.mkdirSync(outputRoot, { recursive: true });
+fs.writeFileSync(path.join(outputRoot, "snapshot-manifest.json"), `${JSON.stringify(manifest, null, 2)}\n`, "utf8");
+process.stdout.write(`m12-git-snapshot-ok requested=${uniqueEntries.size} matched=${matched.length} unmatched=${unresolved.length} output=${path.relative(root, outputRoot).replaceAll(path.sep, "/")}\n`);