feat(upstream): Add dynamic per-request upstream provider and integrate into registries

ts/upstream/interfaces.upstream.ts

@@ -1,4 +1,4 @@
-import type { TRegistryProtocol } from '../core/interfaces.core.js';
+import type { TRegistryProtocol, IRequestActor } from '../core/interfaces.core.js';
 
 /**
  * Scope rule for routing requests to specific upstreams.
@@ -146,6 +146,8 @@ export interface IUpstreamFetchContext {
   headers: Record<string, string>;
   /** Query parameters */
   query: Record<string, string>;
+  /** Actor performing the request (for cache key isolation) */
+  actor?: IRequestActor;
 }
 
 /**
@@ -193,3 +195,80 @@ export const DEFAULT_RESILIENCE_CONFIG: IUpstreamResilienceConfig = {
   circuitBreakerThreshold: 5,
   circuitBreakerResetMs: 30000,
 };
+
+// ============================================================================
+// Upstream Provider Interfaces
+// ============================================================================
+
+/**
+ * Context for resolving upstream configuration.
+ * Passed to IUpstreamProvider per-request to enable dynamic upstream routing.
+ */
+export interface IUpstreamResolutionContext {
+  /** Protocol being accessed */
+  protocol: TRegistryProtocol;
+  /** Resource identifier (package name, repository, coordinates, etc.) */
+  resource: string;
+  /** Extracted scope (e.g., "company" from "@company/pkg", "myorg" from "myorg/image") */
+  scope: string | null;
+  /** Actor performing the request */
+  actor?: IRequestActor;
+  /** HTTP method */
+  method: string;
+  /** Resource type (packument, tarball, manifest, blob, etc.) */
+  resourceType: string;
+}
+
+/**
+ * Dynamic upstream configuration provider.
+ * Implement this interface to provide per-request upstream routing
+ * based on actor context (user, organization, etc.)
+ *
+ * @example
+ * ```typescript
+ * class OrgUpstreamProvider implements IUpstreamProvider {
+ *   constructor(private db: Database) {}
+ *
+ *   async resolveUpstreamConfig(ctx: IUpstreamResolutionContext) {
+ *     if (ctx.actor?.orgId) {
+ *       const orgConfig = await this.db.getOrgUpstream(ctx.actor.orgId, ctx.protocol);
+ *       if (orgConfig) return orgConfig;
+ *     }
+ *     return this.db.getDefaultUpstream(ctx.protocol);
+ *   }
+ * }
+ * ```
+ */
+export interface IUpstreamProvider {
+  /** Optional initialization */
+  init?(): Promise<void>;
+
+  /**
+   * Resolve upstream configuration for a request.
+   * @param context - Information about the current request
+   * @returns Upstream config to use, or null to skip upstream lookup
+   */
+  resolveUpstreamConfig(context: IUpstreamResolutionContext): Promise<IProtocolUpstreamConfig | null>;
+}
+
+/**
+ * Static upstream provider for simple configurations.
+ * Use this when you have fixed upstream registries that don't change per-request.
+ *
+ * @example
+ * ```typescript
+ * const provider = new StaticUpstreamProvider({
+ *   npm: {
+ *     enabled: true,
+ *     upstreams: [{ id: 'npmjs', url: 'https://registry.npmjs.org', priority: 1, enabled: true, auth: { type: 'none' } }],
+ *   },
+ * });
+ * ```
+ */
+export class StaticUpstreamProvider implements IUpstreamProvider {
+  constructor(private configs: Partial<Record<TRegistryProtocol, IProtocolUpstreamConfig>>) {}
+
+  async resolveUpstreamConfig(ctx: IUpstreamResolutionContext): Promise<IProtocolUpstreamConfig | null> {
+    return this.configs[ctx.protocol] ?? null;
+  }
+}