源码快照 @ 2026-09-02 (source-only, 剔除非源码素材)

evals/docs-shots/ctx.ts

@@ -0,0 +1,38 @@
+export type Cleanup = () => void | PromiseLike<void>;
+
+export interface Provider<T> {
+  readonly load: (ctx: Ctx) => Promise<T>;
+  readonly values: WeakMap<Ctx, Promise<T>>;
+}
+
+export function provider<T>(load: (ctx: Ctx) => Promise<T>): Provider<T> {
+  return { load, values: new WeakMap() };
+}
+
+/** A run-scoped, lazy provider cache with last-created-first-disposed cleanup. */
+export class Ctx {
+  private readonly cleanups: Cleanup[] = [];
+
+  use<T>(source: Provider<T>): Promise<T> {
+    const existing = source.values.get(this);
+    if (existing) return existing;
+    const value = source.load(this);
+    source.values.set(this, value);
+    return value;
+  }
+
+  onDispose(cleanup: Cleanup): void {
+    this.cleanups.push(cleanup);
+  }
+
+  async dispose(): Promise<void> {
+    for (const cleanup of this.cleanups.reverse()) {
+      try {
+        await cleanup();
+      } catch (error) {
+        console.error("cleanup failed:", error);
+      }
+    }
+    this.cleanups.length = 0;
+  }
+}