chore: import upstream snapshot with attribution

skills/media-use/scripts/lib/cache.mjs

@@ -0,0 +1,150 @@
+import { readFileSync, writeFileSync, mkdirSync, existsSync, copyFileSync } from "node:fs";
+import { join, basename } from "node:path";
+import { createHash } from "node:crypto";
+import { homedir } from "node:os";
+import { readManifest, appendRecord, normalizePrompt } from "./manifest.mjs";
+
+const SCHEMA_PREFIX = "mu-v1-";
+const KEY_HEX_CHARS = 16;
+const COMPLETE_SENTINEL = ".hf-complete";
+
+export function globalMediaDir() {
+  return join(homedir(), ".media");
+}
+
+export function contentHash(filePath) {
+  const bytes = readFileSync(filePath);
+  return createHash("sha256").update(bytes).digest("hex");
+}
+
+function cacheEntryDir(rootDir, sha) {
+  return join(rootDir, SCHEMA_PREFIX + sha.slice(0, KEY_HEX_CHARS));
+}
+
+function isComplete(entryDir) {
+  return existsSync(join(entryDir, COMPLETE_SENTINEL));
+}
+
+function markComplete(entryDir) {
+  writeFileSync(join(entryDir, COMPLETE_SENTINEL), "", "utf8");
+}
+
+// The manifest helpers append their own ".media" to the dir they get, so the
+// global manifest must be addressed by HOME, not by globalMediaDir() — passing
+// the latter nested it at ~/.media/.media/manifest.jsonl, invisible to the
+// Studio /api/assets/global route (which reads the documented flat path).
+export function readGlobalManifest() {
+  return readManifest(homedir());
+}
+
+// Resolve a content-sha (full or unambiguous prefix) to a reusable global-cache
+// record, for `resolve --reuse <sha>`. Returns null on no match, or
+// { ambiguous: true, count } when a prefix matches multiple distinct entries.
+// Completeness (the .hf-complete sentinel) is left to importFromCache so the
+// caller can surface an "incomplete cache entry" error distinctly from a miss.
+export function findGlobalBySha(shaPrefix) {
+  const p = String(shaPrefix || "")
+    .toLowerCase()
+    .trim();
+  if (!p) return null;
+  const matches = readGlobalManifest().filter(
+    (r) => r.reusable && typeof r.sha === "string" && r.sha.startsWith(p),
+  );
+  if (matches.length === 0) return null;
+  if (matches.length > 1) {
+    const exact = matches.find((r) => r.sha === p);
+    if (exact) return exact;
+    return { ambiguous: true, count: matches.length };
+  }
+  return matches[0];
+}
+
+function validateCacheHit(match) {
+  if (!match?.sha) return null;
+  return isComplete(cacheEntryDir(globalMediaDir(), match.sha)) ? match : null;
+}
+
+export function cacheGet(prompt, type) {
+  const key = normalizePrompt(prompt);
+  if (!key) return null;
+  return validateCacheHit(
+    readGlobalManifest().find(
+      (r) =>
+        r.reusable &&
+        normalizePrompt(r.provenance?.prompt) === key &&
+        (type == null || r.type === type),
+    ),
+  );
+}
+
+export function cacheGetByEntity(entity) {
+  const lower = entity.toLowerCase();
+  return validateCacheHit(
+    readGlobalManifest().find((r) => r.reusable && r.entity && r.entity.toLowerCase() === lower),
+  );
+}
+
+export function cachePut(filePath, record) {
+  const sha = contentHash(filePath);
+  // Idempotent: same content already promoted -> don't duplicate the global
+  // record. ponytail: skips usage_count bump; add it when the metric is needed.
+  const existing = readGlobalManifest().find((r) => r.sha === sha);
+  if (existing) return { sha, cached_path: existing.cached_path, deduped: true };
+
+  const dir = globalMediaDir();
+  const entryDir = cacheEntryDir(dir, sha);
+  mkdirSync(entryDir, { recursive: true });
+
+  const dest = join(entryDir, basename(filePath));
+  copyFileSync(filePath, dest);
+  markComplete(entryDir);
+
+  const globalRecord = {
+    ...record,
+    sha,
+    reusable: true,
+    cached_path: dest,
+  };
+  appendRecord(homedir(), globalRecord);
+  return { sha, cached_path: dest };
+}
+
+export function importFromCache(cacheRecord, projectDir, localId, localPath) {
+  const sha = cacheRecord.sha;
+  const entryDir = cacheEntryDir(globalMediaDir(), sha);
+  if (!isComplete(entryDir)) return null;
+
+  const cachedFile = cacheRecord.cached_path;
+  if (!cachedFile || !existsSync(cachedFile)) return null;
+
+  mkdirSync(join(projectDir, ".media"), { recursive: true });
+  const fullDest = join(projectDir, localPath);
+  mkdirSync(join(fullDest, ".."), { recursive: true });
+  copyFileSync(cachedFile, fullDest);
+
+  const projectRecord = {
+    ...cacheRecord,
+    id: localId,
+    path: localPath,
+    provenance: {
+      ...cacheRecord.provenance,
+      imported_from: sha,
+    },
+  };
+  delete projectRecord.sha;
+  delete projectRecord.reusable;
+  delete projectRecord.cached_path;
+
+  return projectRecord;
+}
+
+export function promote(projectDir, id) {
+  const records = readManifest(projectDir);
+  const record = records.find((r) => r.id === id);
+  if (!record) throw new Error(`asset not found in project manifest: ${id}`);
+
+  const filePath = join(projectDir, record.path);
+  if (!existsSync(filePath)) throw new Error(`asset file not found: ${filePath}`);
+
+  return cachePut(filePath, record);
+}