security: stop spawning child processes through a shell

apps/desktop/src/shell/DesktopShellEnvironment.ts

@@ -241,7 +241,6 @@ const readWindowsEnvironment = Effect.fn("desktop.shellEnvironment.readWindowsEn
       const output = yield* runCommandOutput({
         command,
         args,
-        shell: true,
         timeout: LOGIN_SHELL_TIMEOUT,
       });
       const environment = extractEnvironment(output, names);

apps/server/scripts/cli.ts

@@ -160,8 +160,6 @@ const buildCmd = Command.make(
           cwd: serverDir,
           stdout: config.verbose ? "inherit" : "ignore",
           stderr: "inherit",
-          // Windows needs shell mode to resolve `.cmd` shims on PATH.
-          shell: process.platform === "win32",
         }),
       );
 

apps/server/src/diagnostics/ProcessDiagnostics.ts

@@ -280,7 +280,6 @@ const runProcess = Effect.fn("runProcess")(
     const child = yield* spawner.spawn(
       ChildProcess.make(input.command, input.args, {
         cwd: process.cwd(),
-        shell: process.platform === "win32",
       }),
     );
     const [stdout, stderr, exitCode] = yield* Effect.all(

apps/server/src/environment/Layers/ServerEnvironmentLabel.ts

@@ -59,7 +59,6 @@ const runFriendlyLabelCommand = Effect.fn("runFriendlyLabelCommand")(function* (
       command,
       args,
       timeoutBehavior: "timedOutResult",
-      shell: process.platform === "win32",
     })
     .pipe(Effect.option);
 

apps/server/src/project/Layers/RepositoryIdentityResolver.test.ts

@@ -23,7 +23,6 @@ const git = (cwd: string, args: ReadonlyArray<string>) =>
     return yield* processRunner.run({
       command: "git",
       args: ["-C", cwd, ...args],
-      shell: process.platform === "win32",
     });
   }).pipe(Effect.provide(ProcessRunner.layer));
 

apps/server/src/project/Layers/RepositoryIdentityResolver.ts

@@ -94,7 +94,6 @@ const resolveRepositoryIdentityCacheKey = Effect.fn("resolveRepositoryIdentityCa
       command: "git",
       args: ["-C", cwd, "rev-parse", "--show-toplevel"],
       timeoutBehavior: "timedOutResult",
-      shell: process.platform === "win32",
     })
     .pipe(Effect.option);
   if (topLevelResult._tag === "None" || topLevelResult.value.code !== 0) {
@@ -119,7 +118,6 @@ const resolveRepositoryIdentityFromCacheKey = Effect.fn("resolveRepositoryIdenti
         command: "git",
         args: ["-C", cacheKey, "remote", "-v"],
         timeoutBehavior: "timedOutResult",
-        shell: process.platform === "win32",
       })
       .pipe(Effect.option);
     if (remoteResult._tag === "None" || remoteResult.value.code !== 0) {

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

@@ -383,7 +383,6 @@ function checkWindowsSubprocessActivity(
       timeout: "1500 millis",
       maxOutputBytes: 32_768,
       outputMode: "truncate",
-      shell: process.platform === "win32",
       timeoutBehavior: "timedOutResult",
     });
   }).pipe(

packages/effect-acp/src/client.test.ts

@@ -35,7 +35,6 @@ it.layer(NodeServices.layer)("effect-acp client", (it) => {
       const path = yield* Path.Path;
       const command = ChildProcess.make("bun", ["run", yield* mockPeerPath], {
         cwd: path.join(import.meta.dirname, ".."),
-        shell: process.platform === "win32",
         ...(env ? { env: { ...process.env, ...env } } : {}),
       });
       return yield* spawner.spawn(command);

packages/effect-acp/src/protocol.test.ts

@@ -58,7 +58,6 @@ const makeHandle = (env?: Record<string, string>) =>
     const path = yield* Path.Path;
     const command = ChildProcess.make("bun", ["run", yield* mockPeerPath], {
       cwd: path.join(import.meta.dirname, ".."),
-      shell: process.platform === "win32",
       ...(env ? { env: { ...process.env, ...env } } : {}),
     });
     return yield* spawner.spawn(command);

packages/effect-codex-app-server/src/client.test.ts

@@ -22,7 +22,6 @@ it.layer(NodeServices.layer)("effect-codex-app-server client", (it) => {
       const path = yield* Path.Path;
       const command = ChildProcess.make("bun", ["run", yield* mockPeerPath], {
         cwd: path.join(import.meta.dirname, ".."),
-        shell: process.platform === "win32",
       });
       return yield* spawner.spawn(command);
     });

packages/ssh/src/command.ts

@@ -15,6 +15,7 @@ import { SshCommandError, SshInvalidTargetError } from "./errors.ts";
 
 const PUBLISHABLE_T3_VERSION_PATTERN = /^\d+\.\d+\.\d+(?:-[0-9A-Za-z.-]+)?$/u;
 const DEFAULT_SSH_COMMAND_TIMEOUT_MS = 60_000;
+export const SSH_COMMAND = process.platform === "win32" ? "ssh.exe" : "ssh";
 
 const encoder = new TextEncoder();
 
@@ -153,7 +154,7 @@ const runSshCommandInScope = Effect.fn("ssh/command.runSshCommand.inScope")(func
     Effect.mapError(
       (cause) =>
         new SshCommandError({
-          command: ["ssh"],
+          command: [SSH_COMMAND],
           exitCode: null,
           stderr: "",
           message: "Failed to prepare SSH authentication helpers.",
@@ -172,15 +173,14 @@ const runSshCommandInScope = Effect.fn("ssh/command.runSshCommand.inScope")(func
   const spawner = yield* ChildProcessSpawner.ChildProcessSpawner;
   yield* Effect.logDebug("ssh.command.start", {
     ...sshTargetLogFields(target),
-    command: ["ssh", ...args],
+    command: [SSH_COMMAND, ...args],
     hasStdin: input.stdin !== undefined,
     timeoutMs: input.timeoutMs ?? DEFAULT_SSH_COMMAND_TIMEOUT_MS,
   });
   const child = yield* spawner
     .spawn(
-      ChildProcess.make("ssh", args, {
+      ChildProcess.make(SSH_COMMAND, args, {
         env: environment,
-        shell: process.platform === "win32",
         stdin: {
           stream: stdinStream(input.stdin),
           endOnDone: true,
@@ -192,7 +192,7 @@ const runSshCommandInScope = Effect.fn("ssh/command.runSshCommand.inScope")(func
       Effect.mapError(
         (cause) =>
           new SshCommandError({
-            command: ["ssh", ...args],
+            command: [SSH_COMMAND, ...args],
             exitCode: null,
             stderr: "",
             message:
@@ -215,7 +215,7 @@ const runSshCommandInScope = Effect.fn("ssh/command.runSshCommand.inScope")(func
     Effect.mapError(
       (cause) =>
         new SshCommandError({
-          command: ["ssh", ...args],
+          command: [SSH_COMMAND, ...args],
           exitCode: null,
           stderr: "",
           message:
@@ -228,12 +228,12 @@ const runSshCommandInScope = Effect.fn("ssh/command.runSshCommand.inScope")(func
   if (exitCode !== 0) {
     yield* Effect.logWarning("ssh.command.failed", {
       ...sshTargetLogFields(target),
-      command: ["ssh", ...args],
+      command: [SSH_COMMAND, ...args],
       exitCode,
       stderr,
     });
     return yield* new SshCommandError({
-      command: ["ssh", ...args],
+      command: [SSH_COMMAND, ...args],
       exitCode,
       stderr,
       message: normalizeSshErrorMessage(
@@ -245,7 +245,7 @@ const runSshCommandInScope = Effect.fn("ssh/command.runSshCommand.inScope")(func
 
   yield* Effect.logDebug("ssh.command.succeeded", {
     ...sshTargetLogFields(target),
-    command: ["ssh", ...args],
+    command: [SSH_COMMAND, ...args],
   });
   return { stdout, stderr };
 });
@@ -275,7 +275,7 @@ export const runSshCommand = Effect.fn("ssh/command.runSshCommand")(function* (
               hasStdin: input.stdin !== undefined,
             });
             return yield* new SshCommandError({
-              command: ["ssh"],
+              command: [SSH_COMMAND],
               exitCode: null,
               stderr: "",
               message: `SSH command timed out after ${input.timeoutMs ?? DEFAULT_SSH_COMMAND_TIMEOUT_MS}ms.`,

packages/ssh/src/tunnel.ts

@@ -36,6 +36,7 @@ import {
   remoteStateKey,
   resolveSshTarget,
   runSshCommand,
+  SSH_COMMAND,
   targetConnectionKey,
 } from "./command.ts";
 import {
@@ -1138,7 +1139,7 @@ const startSshTunnel = Effect.fn("ssh/tunnel.startSshTunnel")(function* (input:
     `${input.localPort}:127.0.0.1:${input.remotePort}`,
     hostSpec,
   ];
-  const tunnelCommand = ["ssh", ...args];
+  const tunnelCommand = [SSH_COMMAND, ...args];
   const spawner = yield* ChildProcessSpawner.ChildProcessSpawner;
   const scope = yield* Scope.Scope;
   yield* Effect.logDebug("ssh.tunnel.spawn.start", {
@@ -1151,9 +1152,8 @@ const startSshTunnel = Effect.fn("ssh/tunnel.startSshTunnel")(function* (input:
   });
   const child = yield* spawner
     .spawn(
-      ChildProcess.make("ssh", args, {
+      ChildProcess.make(SSH_COMMAND, args, {
         env: childEnvironment,
-        shell: process.platform === "win32",
         stdin: {
           stream: Stream.empty,
           endOnDone: true,

packages/tailscale/src/tailscale.ts

@@ -10,6 +10,7 @@ export const DEFAULT_TAILSCALE_SERVE_PORT = 443;
 export const TAILSCALE_STATUS_TIMEOUT_MS = 1_500;
 export const TAILSCALE_SERVE_TIMEOUT_MS = 10_000;
 export const TAILSCALE_PROBE_TIMEOUT_MS = 2_500;
+const TAILSCALE_COMMAND = process.platform === "win32" ? "tailscale.exe" : "tailscale";
 
 export class TailscaleCommandError extends Data.TaggedError("TailscaleCommandError")<{
   readonly command: readonly string[];
@@ -133,11 +134,7 @@ export const readTailscaleStatus: Effect.Effect<
   const args = ["status", "--json"];
   const spawner = yield* ChildProcessSpawner.ChildProcessSpawner;
   const child = yield* spawner
-    .spawn(
-      ChildProcess.make("tailscale", args, {
-        shell: process.platform === "win32",
-      }),
-    )
+    .spawn(ChildProcess.make(TAILSCALE_COMMAND, args))
     .pipe(
       Effect.mapError((cause) =>
         tailscaleCommandError(
@@ -212,11 +209,7 @@ const runTailscaleCommand = (
   Effect.gen(function* () {
     const spawner = yield* ChildProcessSpawner.ChildProcessSpawner;
     const child = yield* spawner
-      .spawn(
-        ChildProcess.make("tailscale", args, {
-          shell: process.platform === "win32",
-        }),
-      )
+      .spawn(ChildProcess.make(TAILSCALE_COMMAND, args))
       .pipe(
         Effect.mapError((cause) =>
           tailscaleCommandError(