fix: closing a terminal on Windows never kills its processes

apps/server/src/terminal/Layers/Manager.test.ts

@@ -983,7 +983,10 @@ it.layer(
 
   it.effect("escalates terminal shutdown to SIGKILL when process does not exit in time", () =>
     Effect.gen(function* () {
-      const { manager, ptyAdapter } = yield* createManager(5, { processKillGraceMs: 10 });
+      const { manager, ptyAdapter } = yield* createManager(5, {
+        platform: "linux",
+        processKillGraceMs: 10,
+      });
       yield* manager.open(openInput());
       const process = ptyAdapter.processes[0];
       expect(process).toBeDefined();
@@ -999,6 +1002,25 @@ it.layer(
     }).pipe(Effect.provide(TestClock.layer())),
   );
 
+  it.effect("kills the terminal without a signal on Windows", () =>
+    Effect.gen(function* () {
+      const { manager, ptyAdapter } = yield* createManager(5, {
+        platform: "win32",
+        subprocessInspector: () =>
+          Effect.succeed({ hasRunningSubprocess: false, childCommand: null }),
+      });
+      yield* manager.open(openInput());
+      const process = ptyAdapter.processes[0];
+      expect(process).toBeDefined();
+      if (!process) return;
+
+      yield* manager.close({ threadId: "thread-1" });
+      yield* waitFor(Effect.sync(() => process.killed));
+
+      expect(process.killSignals).toEqual([undefined]);
+    }),
+  );
+
   it.effect("publishes closed events when terminals are explicitly closed", () =>
     Effect.gen(function* () {
       const { manager, getEvents } = yield* createManager();
@@ -1501,6 +1523,7 @@ it.layer(
     Effect.gen(function* () {
       const scope = yield* Scope.make("sequential");
       const { manager, ptyAdapter } = yield* createManager(5, {
+        platform: "linux",
         processKillGraceMs: 10,
       }).pipe(Effect.provideService(Scope.Scope, scope));
       yield* manager.open(openInput());

apps/server/src/terminal/Layers/Manager.ts

@@ -75,7 +75,7 @@ class TerminalProcessSignalError extends Schema.TaggedErrorClass<TerminalProcess
   {
     message: Schema.String,
     cause: Schema.optional(Schema.Defect()),
-    signal: Schema.Literals(["SIGTERM", "SIGKILL"]),
+    signal: Schema.optional(Schema.Literals(["SIGTERM", "SIGKILL"])),
   },
 ) {}
 
@@ -1075,6 +1075,29 @@ export const makeTerminalManagerWithOptions = Effect.fn("makeTerminalManagerWith
       threadId: string,
       terminalId: string,
     ) {
+      if (platform === "win32") {
+        // node-pty throws on Windows whenever a signal is passed; a signal-less
+        // kill terminates every process attached to the pty's console
+        // (shell and child processes such as dev servers), so no escalation step.
+        yield* Effect.try({
+          try: () => process.kill(),
+          catch: (cause) =>
+            new TerminalProcessSignalError({
+              message: "Failed to kill terminal console process tree.",
+              cause,
+            }),
+        }).pipe(
+          Effect.catch((error) =>
+            Effect.logWarning("failed to kill terminal process", {
+              threadId,
+              terminalId,
+              error: error.message,
+            }),
+          ),
+        );
+        return;
+      }
+
       const terminated = yield* Effect.try({
         try: () => process.kill("SIGTERM"),
         catch: (cause) =>