fix(FN-4557): replace loose node-pty ambient shim in @fusion/desktop with accurate IPty surface

Fusion-Task-Id: FN-4557
Fusion-Task-Lineage: 53e20d45-b7e9-43d6-bf6f-2a5a3b568d4a

packages/desktop/src/node-pty.d.ts

@@ -1,12 +1,70 @@
+/** Desktop must mirror dashboard's node-pty shim because desktop typechecks dashboard source via @fusion/dashboard workspace imports. */
 declare module "node-pty" {
+  /**
+   * An object that can be disposed via a dispose function.
+   */
+  export interface IDisposable {
+    dispose(): void;
+  }
+
+  /**
+   * An event that can be listened to.
+   * @returns an IDisposable to stop listening.
+   */
+  export interface IEvent<T> {
+    (listener: (e: T) => unknown): IDisposable;
+  }
+
+  export interface IBasePtyForkOptions {
+    name?: string;
+    cols?: number;
+    rows?: number;
+    cwd?: string;
+    env?: { [key: string]: string | undefined };
+    encoding?: string | null;
+    handleFlowControl?: boolean;
+    flowControlPause?: string;
+    flowControlResume?: string;
+  }
+
+  export interface IPtyForkOptions extends IBasePtyForkOptions {
+    uid?: number;
+    gid?: number;
+  }
+
+  export interface IWindowsPtyForkOptions extends IBasePtyForkOptions {
+    useConpty?: boolean;
+    useConptyDll?: boolean;
+    conptyInheritCursor?: boolean;
+  }
+
+  /**
+   * An interface representing a pseudoterminal.
+   */
   export interface IPty {
-    [key: string]: unknown;
+    readonly pid: number;
+    readonly cols: number;
+    readonly rows: number;
+    readonly process: string;
+    handleFlowControl: boolean;
+    readonly onData: IEvent<string>;
+    readonly onExit: IEvent<{ exitCode: number; signal?: number }>;
+    resize(columns: number, rows: number): void;
+    on(event: "data", listener: (data: string) => void): void;
+    on(event: "exit", listener: (exitCode: number, signal?: number) => void): void;
+    clear(): void;
+    write(data: string): void;
+    kill(signal?: string): void;
+    pause(): void;
+    resume(): void;
   }
-  export interface IPtyForkOptions {
-    [key: string]: unknown;
-  }
-  export interface IWindowsPtyForkOptions extends IPtyForkOptions {
-    [key: string]: unknown;
-  }
-  export function spawn(...args: unknown[]): IPty;
+
+  /**
+   * Forks a process as a pseudoterminal.
+   */
+  export function spawn(
+    file: string,
+    args: string[] | string,
+    options: IPtyForkOptions | IWindowsPtyForkOptions,
+  ): IPty;
 }