feat(api): add terminal WebSocket gateway with PTY session management (#515)

Co-authored-by: Jason Woltje <jason@diversecanvas.com>
Co-committed-by: Jason Woltje <jason@diversecanvas.com>

apps/api/src/terminal/terminal.gateway.ts

@@ -0,0 +1,423 @@
+/**
+ * TerminalGateway
+ *
+ * WebSocket gateway for real-time PTY terminal sessions.
+ * Uses the `/terminal` namespace to keep terminal traffic separate
+ * from the main WebSocket gateway.
+ *
+ * Protocol:
+ * 1. Client connects with auth token in handshake
+ * 2. Client emits `terminal:create` to spawn a new PTY session
+ * 3. Server emits `terminal:created` with { sessionId }
+ * 4. Client emits `terminal:input` with { sessionId, data } to send keystrokes
+ * 5. Server emits `terminal:output` with { sessionId, data } for stdout/stderr
+ * 6. Client emits `terminal:resize` with { sessionId, cols, rows } on window resize
+ * 7. Client emits `terminal:close` with { sessionId } to terminate the PTY
+ * 8. Server emits `terminal:exit` with { sessionId, exitCode, signal } on PTY exit
+ *
+ * Authentication:
+ * - Same pattern as websocket.gateway.ts and speech.gateway.ts
+ * - Token extracted from handshake.auth.token / query.token / Authorization header
+ *
+ * Workspace isolation:
+ * - Clients join room `terminal:{workspaceId}` on connect
+ * - Sessions are scoped to workspace; cross-workspace access is denied
+ */
+
+import {
+  WebSocketGateway as WSGateway,
+  WebSocketServer,
+  SubscribeMessage,
+  OnGatewayConnection,
+  OnGatewayDisconnect,
+} from "@nestjs/websockets";
+import { Logger } from "@nestjs/common";
+import { Server, Socket } from "socket.io";
+import { AuthService } from "../auth/auth.service";
+import { PrismaService } from "../prisma/prisma.service";
+import { TerminalService } from "./terminal.service";
+import {
+  CreateTerminalDto,
+  TerminalInputDto,
+  TerminalResizeDto,
+  CloseTerminalDto,
+} from "./terminal.dto";
+import { validate } from "class-validator";
+import { plainToInstance } from "class-transformer";
+
+// ==========================================
+// Types
+// ==========================================
+
+interface AuthenticatedSocket extends Socket {
+  data: {
+    userId?: string;
+    workspaceId?: string;
+  };
+}
+
+// ==========================================
+// Gateway
+// ==========================================
+
+@WSGateway({
+  namespace: "/terminal",
+  cors: {
+    origin: process.env.WEB_URL ?? "http://localhost:3000",
+    credentials: true,
+  },
+})
+export class TerminalGateway implements OnGatewayConnection, OnGatewayDisconnect {
+  @WebSocketServer()
+  server!: Server;
+
+  private readonly logger = new Logger(TerminalGateway.name);
+  private readonly CONNECTION_TIMEOUT_MS = 5000;
+
+  constructor(
+    private readonly authService: AuthService,
+    private readonly prisma: PrismaService,
+    private readonly terminalService: TerminalService
+  ) {}
+
+  // ==========================================
+  // Connection lifecycle
+  // ==========================================
+
+  /**
+   * Authenticate client on connection using handshake token.
+   * Validates workspace membership and joins the workspace-scoped room.
+   */
+  async handleConnection(client: Socket): Promise<void> {
+    const authenticatedClient = client as AuthenticatedSocket;
+
+    const timeoutId = setTimeout(() => {
+      if (!authenticatedClient.data.userId) {
+        this.logger.warn(
+          `Terminal client ${authenticatedClient.id} timed out during authentication`
+        );
+        authenticatedClient.emit("terminal:error", {
+          message: "Authentication timed out.",
+        });
+        authenticatedClient.disconnect();
+      }
+    }, this.CONNECTION_TIMEOUT_MS);
+
+    try {
+      const token = this.extractTokenFromHandshake(authenticatedClient);
+
+      if (!token) {
+        this.logger.warn(`Terminal client ${authenticatedClient.id} connected without token`);
+        authenticatedClient.emit("terminal:error", {
+          message: "Authentication failed: no token provided.",
+        });
+        authenticatedClient.disconnect();
+        clearTimeout(timeoutId);
+        return;
+      }
+
+      const sessionData = await this.authService.verifySession(token);
+
+      if (!sessionData) {
+        this.logger.warn(`Terminal client ${authenticatedClient.id} has invalid token`);
+        authenticatedClient.emit("terminal:error", {
+          message: "Authentication failed: invalid or expired token.",
+        });
+        authenticatedClient.disconnect();
+        clearTimeout(timeoutId);
+        return;
+      }
+
+      const user = sessionData.user as { id: string };
+      const userId = user.id;
+
+      const workspaceMembership = await this.prisma.workspaceMember.findFirst({
+        where: { userId },
+        select: { workspaceId: true, userId: true, role: true },
+      });
+
+      if (!workspaceMembership) {
+        this.logger.warn(`Terminal user ${userId} has no workspace access`);
+        authenticatedClient.emit("terminal:error", {
+          message: "Authentication failed: no workspace access.",
+        });
+        authenticatedClient.disconnect();
+        clearTimeout(timeoutId);
+        return;
+      }
+
+      authenticatedClient.data.userId = userId;
+      authenticatedClient.data.workspaceId = workspaceMembership.workspaceId;
+
+      // Join workspace-scoped terminal room
+      const room = this.getWorkspaceRoom(workspaceMembership.workspaceId);
+      await authenticatedClient.join(room);
+
+      clearTimeout(timeoutId);
+      this.logger.log(
+        `Terminal client ${authenticatedClient.id} connected (user: ${userId}, workspace: ${workspaceMembership.workspaceId})`
+      );
+    } catch (error) {
+      clearTimeout(timeoutId);
+      this.logger.error(
+        `Authentication failed for terminal client ${authenticatedClient.id}:`,
+        error instanceof Error ? error.message : "Unknown error"
+      );
+      authenticatedClient.emit("terminal:error", {
+        message: "Authentication failed: an unexpected error occurred.",
+      });
+      authenticatedClient.disconnect();
+    }
+  }
+
+  /**
+   * Clean up all PTY sessions for this client's workspace on disconnect.
+   */
+  handleDisconnect(client: Socket): void {
+    const authenticatedClient = client as AuthenticatedSocket;
+    const { workspaceId, userId } = authenticatedClient.data;
+
+    if (workspaceId) {
+      this.terminalService.closeWorkspaceSessions(workspaceId);
+
+      const room = this.getWorkspaceRoom(workspaceId);
+      void authenticatedClient.leave(room);
+      this.logger.log(
+        `Terminal client ${authenticatedClient.id} disconnected (user: ${userId ?? "unknown"}, workspace: ${workspaceId})`
+      );
+    } else {
+      this.logger.debug(`Terminal client ${authenticatedClient.id} disconnected (unauthenticated)`);
+    }
+  }
+
+  // ==========================================
+  // Terminal events
+  // ==========================================
+
+  /**
+   * Spawn a new PTY session for the connected client.
+   *
+   * Emits `terminal:created` with { sessionId, name, cols, rows } on success.
+   * Emits `terminal:error` on failure.
+   */
+  @SubscribeMessage("terminal:create")
+  async handleCreate(client: Socket, payload: unknown): Promise<void> {
+    const authenticatedClient = client as AuthenticatedSocket;
+    const { userId, workspaceId } = authenticatedClient.data;
+
+    if (!userId || !workspaceId) {
+      authenticatedClient.emit("terminal:error", {
+        message: "Not authenticated. Connect with a valid token.",
+      });
+      return;
+    }
+
+    // Validate DTO
+    const dto = plainToInstance(CreateTerminalDto, payload ?? {});
+    const errors = await validate(dto);
+    if (errors.length > 0) {
+      const messages = errors.map((e) => Object.values(e.constraints ?? {}).join(", ")).join("; ");
+      authenticatedClient.emit("terminal:error", {
+        message: `Invalid payload: ${messages}`,
+      });
+      return;
+    }
+
+    try {
+      const result = this.terminalService.createSession(authenticatedClient, {
+        workspaceId,
+        socketId: authenticatedClient.id,
+        ...(dto.name !== undefined ? { name: dto.name } : {}),
+        ...(dto.cols !== undefined ? { cols: dto.cols } : {}),
+        ...(dto.rows !== undefined ? { rows: dto.rows } : {}),
+        ...(dto.cwd !== undefined ? { cwd: dto.cwd } : {}),
+      });
+
+      authenticatedClient.emit("terminal:created", {
+        sessionId: result.sessionId,
+        name: result.name,
+        cols: result.cols,
+        rows: result.rows,
+      });
+
+      this.logger.log(
+        `Terminal session ${result.sessionId} created for client ${authenticatedClient.id} (workspace: ${workspaceId})`
+      );
+    } catch (error) {
+      const message = error instanceof Error ? error.message : String(error);
+      this.logger.error(
+        `Failed to create terminal session for client ${authenticatedClient.id}: ${message}`
+      );
+      authenticatedClient.emit("terminal:error", { message });
+    }
+  }
+
+  /**
+   * Write input data to an existing PTY session.
+   *
+   * Emits `terminal:error` if the session is not found or unauthorized.
+   */
+  @SubscribeMessage("terminal:input")
+  async handleInput(client: Socket, payload: unknown): Promise<void> {
+    const authenticatedClient = client as AuthenticatedSocket;
+    const { userId, workspaceId } = authenticatedClient.data;
+
+    if (!userId || !workspaceId) {
+      authenticatedClient.emit("terminal:error", {
+        message: "Not authenticated. Connect with a valid token.",
+      });
+      return;
+    }
+
+    const dto = plainToInstance(TerminalInputDto, payload ?? {});
+    const errors = await validate(dto);
+    if (errors.length > 0) {
+      const messages = errors.map((e) => Object.values(e.constraints ?? {}).join(", ")).join("; ");
+      authenticatedClient.emit("terminal:error", {
+        message: `Invalid payload: ${messages}`,
+      });
+      return;
+    }
+
+    if (!this.terminalService.sessionBelongsToWorkspace(dto.sessionId, workspaceId)) {
+      authenticatedClient.emit("terminal:error", {
+        message: `Terminal session ${dto.sessionId} not found or unauthorized.`,
+      });
+      return;
+    }
+
+    try {
+      this.terminalService.writeToSession(dto.sessionId, dto.data);
+    } catch (error) {
+      const message = error instanceof Error ? error.message : String(error);
+      this.logger.warn(`Failed to write to terminal session ${dto.sessionId}: ${message}`);
+      authenticatedClient.emit("terminal:error", { message });
+    }
+  }
+
+  /**
+   * Resize an existing PTY session.
+   *
+   * Emits `terminal:error` if the session is not found or unauthorized.
+   */
+  @SubscribeMessage("terminal:resize")
+  async handleResize(client: Socket, payload: unknown): Promise<void> {
+    const authenticatedClient = client as AuthenticatedSocket;
+    const { userId, workspaceId } = authenticatedClient.data;
+
+    if (!userId || !workspaceId) {
+      authenticatedClient.emit("terminal:error", {
+        message: "Not authenticated. Connect with a valid token.",
+      });
+      return;
+    }
+
+    const dto = plainToInstance(TerminalResizeDto, payload ?? {});
+    const errors = await validate(dto);
+    if (errors.length > 0) {
+      const messages = errors.map((e) => Object.values(e.constraints ?? {}).join(", ")).join("; ");
+      authenticatedClient.emit("terminal:error", {
+        message: `Invalid payload: ${messages}`,
+      });
+      return;
+    }
+
+    if (!this.terminalService.sessionBelongsToWorkspace(dto.sessionId, workspaceId)) {
+      authenticatedClient.emit("terminal:error", {
+        message: `Terminal session ${dto.sessionId} not found or unauthorized.`,
+      });
+      return;
+    }
+
+    try {
+      this.terminalService.resizeSession(dto.sessionId, dto.cols, dto.rows);
+    } catch (error) {
+      const message = error instanceof Error ? error.message : String(error);
+      this.logger.warn(`Failed to resize terminal session ${dto.sessionId}: ${message}`);
+      authenticatedClient.emit("terminal:error", { message });
+    }
+  }
+
+  /**
+   * Kill and close an existing PTY session.
+   *
+   * Emits `terminal:error` if the session is not found or unauthorized.
+   */
+  @SubscribeMessage("terminal:close")
+  async handleClose(client: Socket, payload: unknown): Promise<void> {
+    const authenticatedClient = client as AuthenticatedSocket;
+    const { userId, workspaceId } = authenticatedClient.data;
+
+    if (!userId || !workspaceId) {
+      authenticatedClient.emit("terminal:error", {
+        message: "Not authenticated. Connect with a valid token.",
+      });
+      return;
+    }
+
+    const dto = plainToInstance(CloseTerminalDto, payload ?? {});
+    const errors = await validate(dto);
+    if (errors.length > 0) {
+      const messages = errors.map((e) => Object.values(e.constraints ?? {}).join(", ")).join("; ");
+      authenticatedClient.emit("terminal:error", {
+        message: `Invalid payload: ${messages}`,
+      });
+      return;
+    }
+
+    if (!this.terminalService.sessionBelongsToWorkspace(dto.sessionId, workspaceId)) {
+      authenticatedClient.emit("terminal:error", {
+        message: `Terminal session ${dto.sessionId} not found or unauthorized.`,
+      });
+      return;
+    }
+
+    const closed = this.terminalService.closeSession(dto.sessionId);
+    if (!closed) {
+      authenticatedClient.emit("terminal:error", {
+        message: `Terminal session ${dto.sessionId} not found.`,
+      });
+      return;
+    }
+
+    this.logger.log(`Terminal session ${dto.sessionId} closed by client ${authenticatedClient.id}`);
+  }
+
+  // ==========================================
+  // Private helpers
+  // ==========================================
+
+  /**
+   * Extract authentication token from Socket.IO handshake.
+   * Checks auth.token, query.token, and Authorization header (in that order).
+   */
+  private extractTokenFromHandshake(client: Socket): string | undefined {
+    const authToken = client.handshake.auth.token as unknown;
+    if (typeof authToken === "string" && authToken.length > 0) {
+      return authToken;
+    }
+
+    const queryToken = client.handshake.query.token as unknown;
+    if (typeof queryToken === "string" && queryToken.length > 0) {
+      return queryToken;
+    }
+
+    const authHeader = client.handshake.headers.authorization as unknown;
+    if (typeof authHeader === "string") {
+      const parts = authHeader.split(" ");
+      const [type, token] = parts;
+      if (type === "Bearer" && token) {
+        return token;
+      }
+    }
+
+    return undefined;
+  }
+
+  /**
+   * Get the workspace-scoped room name for the terminal namespace.
+   */
+  private getWorkspaceRoom(workspaceId: string): string {
+    return `terminal:${workspaceId}`;
+  }
+}