test: enforce npm pack budget in install smoke

scripts/lib/npm-pack-budget.d.mts

@@ -0,0 +1,22 @@
+export type NpmPackBudgetResult = {
+  filename?: string;
+  unpackedSize?: number;
+};
+
+export declare const NPM_PACK_UNPACKED_SIZE_BUDGET_BYTES: number;
+
+export declare function formatMiB(bytes: number): string;
+
+export declare function formatPackUnpackedSizeBudgetError(params: {
+  budgetBytes?: number;
+  label: string;
+  unpackedSize: number;
+}): string;
+
+export declare function collectPackUnpackedSizeErrors(
+  results: Iterable<NpmPackBudgetResult>,
+  options?: {
+    budgetBytes?: number;
+    missingDataMessage?: string;
+  },
+): string[];

scripts/lib/npm-pack-budget.mjs

@@ -0,0 +1,55 @@
+// 2026.3.12 ballooned to ~213.6 MiB unpacked and correlated with low-memory
+// startup/doctor OOM reports. 2026.4.12 intentionally stages Matrix runtime
+// dependencies, including crypto wasm, so packaged installs do not miss Docker
+// and gateway runtime dependencies. Keep the budget below the 2026.3.12 bloat
+// level while allowing that mirrored runtime surface.
+export const NPM_PACK_UNPACKED_SIZE_BUDGET_BYTES = 202 * 1024 * 1024;
+
+export function formatMiB(bytes) {
+  return `${(bytes / (1024 * 1024)).toFixed(1)} MiB`;
+}
+
+function resolvePackResultLabel(entry, index) {
+  return entry.filename?.trim() || `pack result #${index + 1}`;
+}
+
+export function formatPackUnpackedSizeBudgetError(params) {
+  const budgetBytes = params.budgetBytes ?? NPM_PACK_UNPACKED_SIZE_BUDGET_BYTES;
+  return [
+    `${params.label} unpackedSize ${params.unpackedSize} bytes (${formatMiB(params.unpackedSize)}) exceeds budget ${budgetBytes} bytes (${formatMiB(budgetBytes)}).`,
+    "Investigate duplicate channel shims, copied extension trees, or other accidental pack bloat before release.",
+  ].join(" ");
+}
+
+export function collectPackUnpackedSizeErrors(results, options = {}) {
+  const entries = Array.from(results);
+  const errors = [];
+  const budgetBytes = options.budgetBytes ?? NPM_PACK_UNPACKED_SIZE_BUDGET_BYTES;
+  let checkedCount = 0;
+
+  for (const [index, entry] of entries.entries()) {
+    if (typeof entry.unpackedSize !== "number" || !Number.isFinite(entry.unpackedSize)) {
+      continue;
+    }
+    checkedCount += 1;
+    if (entry.unpackedSize <= budgetBytes) {
+      continue;
+    }
+    errors.push(
+      formatPackUnpackedSizeBudgetError({
+        budgetBytes,
+        label: resolvePackResultLabel(entry, index),
+        unpackedSize: entry.unpackedSize,
+      }),
+    );
+  }
+
+  if (entries.length > 0 && checkedCount === 0) {
+    errors.push(
+      options.missingDataMessage ??
+        "npm pack --dry-run produced no unpackedSize data; pack size budget was not verified.",
+    );
+  }
+
+  return errors;
+}