fix(SEC-ORCH-2): Add API key authentication to orchestrator API

Add OrchestratorApiKeyGuard to protect agent management endpoints (spawn,
kill, kill-all, status) from unauthorized access. Uses X-API-Key header
with constant-time comparison to prevent timing attacks.

- Create apps/orchestrator/src/common/guards/api-key.guard.ts
- Add comprehensive tests for all guard scenarios
- Apply guard to AgentsController (controller-level protection)
- Document ORCHESTRATOR_API_KEY in .env.example files
- Health endpoints remain unauthenticated for monitoring

Security: Prevents unauthorized users from draining API credits or
killing all agents via unprotected endpoints.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/orchestrator/.env.example

@@ -21,6 +21,13 @@ GIT_USER_EMAIL="orchestrator@mosaicstack.dev"
 KILLSWITCH_ENABLED=true
 SANDBOX_ENABLED=true
 
+# API Authentication
+# CRITICAL: Generate a random API key with at least 32 characters
+# Example: openssl rand -base64 32
+# Required for all /agents/* endpoints (spawn, kill, kill-all, status)
+# Health endpoints (/health/*) remain unauthenticated
+ORCHESTRATOR_API_KEY=REPLACE_WITH_RANDOM_API_KEY_MINIMUM_32_CHARS
+
 # Quality Gates
 # YOLO mode bypasses all quality gates (default: false)
 # WARNING: Only enable for development/testing. Not recommended for production.

apps/orchestrator/src/api/agents/agents.controller.ts

@@ -10,17 +10,23 @@ import {
   UsePipes,
   ValidationPipe,
   HttpCode,
+  UseGuards,
 } from "@nestjs/common";
 import { QueueService } from "../../queue/queue.service";
 import { AgentSpawnerService } from "../../spawner/agent-spawner.service";
 import { AgentLifecycleService } from "../../spawner/agent-lifecycle.service";
 import { KillswitchService } from "../../killswitch/killswitch.service";
 import { SpawnAgentDto, SpawnAgentResponseDto } from "./dto/spawn-agent.dto";
+import { OrchestratorApiKeyGuard } from "../../common/guards/api-key.guard";
 
 /**
  * Controller for agent management endpoints
+ *
+ * All endpoints require API key authentication via X-API-Key header.
+ * Set ORCHESTRATOR_API_KEY environment variable to configure the expected key.
  */
 @Controller("agents")
+@UseGuards(OrchestratorApiKeyGuard)
 export class AgentsController {
   private readonly logger = new Logger(AgentsController.name);
 

apps/orchestrator/src/api/agents/agents.module.ts

@@ -4,9 +4,11 @@ import { QueueModule } from "../../queue/queue.module";
 import { SpawnerModule } from "../../spawner/spawner.module";
 import { KillswitchModule } from "../../killswitch/killswitch.module";
 import { ValkeyModule } from "../../valkey/valkey.module";
+import { OrchestratorApiKeyGuard } from "../../common/guards/api-key.guard";
 
 @Module({
   imports: [QueueModule, SpawnerModule, KillswitchModule, ValkeyModule],
   controllers: [AgentsController],
+  providers: [OrchestratorApiKeyGuard],
 })
 export class AgentsModule {}

apps/orchestrator/src/common/guards/api-key.guard.spec.ts

@@ -0,0 +1,169 @@
+import { describe, it, expect, beforeEach, vi } from "vitest";
+import { ExecutionContext, UnauthorizedException } from "@nestjs/common";
+import { ConfigService } from "@nestjs/config";
+import { OrchestratorApiKeyGuard } from "./api-key.guard";
+
+describe("OrchestratorApiKeyGuard", () => {
+  let guard: OrchestratorApiKeyGuard;
+  let mockConfigService: ConfigService;
+
+  beforeEach(() => {
+    mockConfigService = {
+      get: vi.fn(),
+    } as unknown as ConfigService;
+
+    guard = new OrchestratorApiKeyGuard(mockConfigService);
+  });
+
+  const createMockExecutionContext = (headers: Record<string, string>): ExecutionContext => {
+    return {
+      switchToHttp: () => ({
+        getRequest: () => ({
+          headers,
+        }),
+      }),
+    } as ExecutionContext;
+  };
+
+  describe("canActivate", () => {
+    it("should return true when valid API key is provided", () => {
+      const validApiKey = "test-orchestrator-api-key-12345";
+      vi.mocked(mockConfigService.get).mockReturnValue(validApiKey);
+
+      const context = createMockExecutionContext({
+        "x-api-key": validApiKey,
+      });
+
+      const result = guard.canActivate(context);
+
+      expect(result).toBe(true);
+      expect(mockConfigService.get).toHaveBeenCalledWith("ORCHESTRATOR_API_KEY");
+    });
+
+    it("should throw UnauthorizedException when no API key is provided", () => {
+      const context = createMockExecutionContext({});
+
+      expect(() => guard.canActivate(context)).toThrow(UnauthorizedException);
+      expect(() => guard.canActivate(context)).toThrow("No API key provided");
+    });
+
+    it("should throw UnauthorizedException when API key is invalid", () => {
+      const validApiKey = "correct-orchestrator-api-key";
+      const invalidApiKey = "wrong-api-key";
+
+      vi.mocked(mockConfigService.get).mockReturnValue(validApiKey);
+
+      const context = createMockExecutionContext({
+        "x-api-key": invalidApiKey,
+      });
+
+      expect(() => guard.canActivate(context)).toThrow(UnauthorizedException);
+      expect(() => guard.canActivate(context)).toThrow("Invalid API key");
+    });
+
+    it("should throw UnauthorizedException when ORCHESTRATOR_API_KEY is not configured", () => {
+      vi.mocked(mockConfigService.get).mockReturnValue(undefined);
+
+      const context = createMockExecutionContext({
+        "x-api-key": "some-key",
+      });
+
+      expect(() => guard.canActivate(context)).toThrow(UnauthorizedException);
+      expect(() => guard.canActivate(context)).toThrow("API key authentication not configured");
+    });
+
+    it("should handle uppercase header name (X-API-Key)", () => {
+      const validApiKey = "test-orchestrator-api-key-12345";
+      vi.mocked(mockConfigService.get).mockReturnValue(validApiKey);
+
+      const context = createMockExecutionContext({
+        "X-API-Key": validApiKey,
+      });
+
+      const result = guard.canActivate(context);
+
+      expect(result).toBe(true);
+    });
+
+    it("should handle mixed case header name (X-Api-Key)", () => {
+      const validApiKey = "test-orchestrator-api-key-12345";
+      vi.mocked(mockConfigService.get).mockReturnValue(validApiKey);
+
+      const context = createMockExecutionContext({
+        "X-Api-Key": validApiKey,
+      });
+
+      const result = guard.canActivate(context);
+
+      expect(result).toBe(true);
+    });
+
+    it("should reject empty string API key", () => {
+      vi.mocked(mockConfigService.get).mockReturnValue("valid-key");
+
+      const context = createMockExecutionContext({
+        "x-api-key": "",
+      });
+
+      expect(() => guard.canActivate(context)).toThrow(UnauthorizedException);
+      expect(() => guard.canActivate(context)).toThrow("No API key provided");
+    });
+
+    it("should reject whitespace-only API key", () => {
+      vi.mocked(mockConfigService.get).mockReturnValue("valid-key");
+
+      const context = createMockExecutionContext({
+        "x-api-key": "   ",
+      });
+
+      expect(() => guard.canActivate(context)).toThrow(UnauthorizedException);
+      expect(() => guard.canActivate(context)).toThrow("No API key provided");
+    });
+
+    it("should use constant-time comparison to prevent timing attacks", () => {
+      const validApiKey = "test-api-key-12345";
+      vi.mocked(mockConfigService.get).mockReturnValue(validApiKey);
+
+      const startTime = Date.now();
+      const context1 = createMockExecutionContext({
+        "x-api-key": "wrong-key-short",
+      });
+
+      try {
+        guard.canActivate(context1);
+      } catch {
+        // Expected to fail
+      }
+      const shortKeyTime = Date.now() - startTime;
+
+      const startTime2 = Date.now();
+      const context2 = createMockExecutionContext({
+        "x-api-key": "test-api-key-12344", // Very close to correct key
+      });
+
+      try {
+        guard.canActivate(context2);
+      } catch {
+        // Expected to fail
+      }
+      const longKeyTime = Date.now() - startTime2;
+
+      // Times should be similar (within 10ms) to prevent timing attacks
+      // Note: This is a simplified test; real timing attack prevention
+      // is handled by crypto.timingSafeEqual
+      expect(Math.abs(shortKeyTime - longKeyTime)).toBeLessThan(10);
+    });
+
+    it("should reject keys with different lengths even if prefix matches", () => {
+      const validApiKey = "orchestrator-secret-key-abc123";
+      vi.mocked(mockConfigService.get).mockReturnValue(validApiKey);
+
+      const context = createMockExecutionContext({
+        "x-api-key": "orchestrator-secret-key-abc123-extra",
+      });
+
+      expect(() => guard.canActivate(context)).toThrow(UnauthorizedException);
+      expect(() => guard.canActivate(context)).toThrow("Invalid API key");
+    });
+  });
+});

apps/orchestrator/src/common/guards/api-key.guard.ts

@@ -0,0 +1,82 @@
+import { Injectable, CanActivate, ExecutionContext, UnauthorizedException } from "@nestjs/common";
+import { ConfigService } from "@nestjs/config";
+import { timingSafeEqual } from "crypto";
+
+/**
+ * OrchestratorApiKeyGuard - Authentication guard for orchestrator API endpoints
+ *
+ * Validates the X-API-Key header against the ORCHESTRATOR_API_KEY environment variable.
+ * Uses constant-time comparison to prevent timing attacks.
+ *
+ * Usage:
+ * @UseGuards(OrchestratorApiKeyGuard)
+ * @Controller('agents')
+ * export class AgentsController { ... }
+ */
+@Injectable()
+export class OrchestratorApiKeyGuard implements CanActivate {
+  constructor(private readonly configService: ConfigService) {}
+
+  canActivate(context: ExecutionContext): boolean {
+    const request = context.switchToHttp().getRequest<{ headers: Record<string, string> }>();
+    const providedKey = this.extractApiKeyFromHeader(request);
+
+    if (!providedKey) {
+      throw new UnauthorizedException("No API key provided");
+    }
+
+    const configuredKey = this.configService.get<string>("ORCHESTRATOR_API_KEY");
+
+    if (!configuredKey) {
+      throw new UnauthorizedException("API key authentication not configured");
+    }
+
+    if (!this.isValidApiKey(providedKey, configuredKey)) {
+      throw new UnauthorizedException("Invalid API key");
+    }
+
+    return true;
+  }
+
+  /**
+   * Extract API key from X-API-Key header (case-insensitive)
+   */
+  private extractApiKeyFromHeader(request: {
+    headers: Record<string, string>;
+  }): string | undefined {
+    const headers = request.headers;
+
+    // Check common variations (lowercase, uppercase, mixed case)
+    // HTTP headers are typically normalized to lowercase, but we check common variations for safety
+    const apiKey =
+      headers["x-api-key"] || headers["X-API-Key"] || headers["X-Api-Key"] || undefined;
+
+    // Return undefined if key is empty string
+    if (typeof apiKey === "string" && apiKey.trim() === "") {
+      return undefined;
+    }
+
+    return apiKey;
+  }
+
+  /**
+   * Validate API key using constant-time comparison to prevent timing attacks
+   */
+  private isValidApiKey(providedKey: string, configuredKey: string): boolean {
+    try {
+      // Convert strings to buffers for constant-time comparison
+      const providedBuffer = Buffer.from(providedKey, "utf8");
+      const configuredBuffer = Buffer.from(configuredKey, "utf8");
+
+      // Keys must be same length for timingSafeEqual
+      if (providedBuffer.length !== configuredBuffer.length) {
+        return false;
+      }
+
+      return timingSafeEqual(providedBuffer, configuredBuffer);
+    } catch {
+      // If comparison fails for any reason, reject
+      return false;
+    }
+  }
+}