feat(core): Implement JIT context manager and setting (#14324)

Co-authored-by: Abhi <43648792+abhipatel12@users.noreply.github.com>

packages/core/src/services/contextManager.ts

@@ -0,0 +1,111 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import {
+  loadGlobalMemory,
+  loadEnvironmentMemory,
+  loadJitSubdirectoryMemory,
+  concatenateInstructions,
+} from '../utils/memoryDiscovery.js';
+import type { ExtensionLoader } from '../utils/extensionLoader.js';
+import type { Config } from '../config/config.js';
+
+export class ContextManager {
+  private readonly loadedPaths: Set<string> = new Set();
+  private readonly config: Config;
+  private globalMemory: string = '';
+  private environmentMemory: string = '';
+
+  constructor(config: Config) {
+    this.config = config;
+  }
+
+  /**
+   * Loads the global memory (Tier 1) and returns the formatted content.
+   */
+  async loadGlobalMemory(): Promise<string> {
+    const result = await loadGlobalMemory(this.config.getDebugMode());
+    this.markAsLoaded(result.files.map((f) => f.path));
+    this.globalMemory = concatenateInstructions(
+      result.files.map((f) => ({ filePath: f.path, content: f.content })),
+      this.config.getWorkingDir(),
+    );
+    return this.globalMemory;
+  }
+
+  /**
+   * Loads the environment memory (Tier 2) and returns the formatted content.
+   */
+  async loadEnvironmentMemory(
+    trustedRoots: string[],
+    extensionLoader: ExtensionLoader,
+  ): Promise<string> {
+    const result = await loadEnvironmentMemory(
+      trustedRoots,
+      extensionLoader,
+      this.config.getDebugMode(),
+    );
+    this.markAsLoaded(result.files.map((f) => f.path));
+    this.environmentMemory = concatenateInstructions(
+      result.files.map((f) => ({ filePath: f.path, content: f.content })),
+      this.config.getWorkingDir(),
+    );
+    return this.environmentMemory;
+  }
+
+  /**
+   * Discovers and loads context for a specific accessed path (Tier 3 - JIT).
+   * Traverses upwards from the accessed path to the project root.
+   */
+  async discoverContext(
+    accessedPath: string,
+    trustedRoots: string[],
+  ): Promise<string> {
+    const result = await loadJitSubdirectoryMemory(
+      accessedPath,
+      trustedRoots,
+      this.loadedPaths,
+      this.config.getDebugMode(),
+    );
+
+    if (result.files.length === 0) {
+      return '';
+    }
+
+    this.markAsLoaded(result.files.map((f) => f.path));
+    return concatenateInstructions(
+      result.files.map((f) => ({ filePath: f.path, content: f.content })),
+      this.config.getWorkingDir(),
+    );
+  }
+
+  getGlobalMemory(): string {
+    return this.globalMemory;
+  }
+
+  getEnvironmentMemory(): string {
+    return this.environmentMemory;
+  }
+
+  private markAsLoaded(paths: string[]): void {
+    for (const p of paths) {
+      this.loadedPaths.add(p);
+    }
+  }
+
+  /**
+   * Resets the loaded paths tracking and memory. Useful for testing or full reloads.
+   */
+  reset(): void {
+    this.loadedPaths.clear();
+    this.globalMemory = '';
+    this.environmentMemory = '';
+  }
+
+  getLoadedPaths(): ReadonlySet<string> {
+    return this.loadedPaths;
+  }
+}