fix: add quotePath to buildTerminateCommand for SSH tilde support

buildTerminateCommand now accepts optional quotePath parameter (like
buildSpawnCommand) to avoid double-quoting when used with SSH paths.

SSHBackgroundHandle.terminate() passes raw path + expandTildeForSSH
instead of pre-expanded path that would get quoted again by shellQuote.

Author: ethanndickson

src/node/runtime/SSHBackgroundHandle.ts

@@ -61,9 +61,10 @@ export class SSHBackgroundHandle implements BackgroundHandle {
 
     try {
       // Use shared buildTerminateCommand for parity with Local
-      // Must expand tilde - buildTerminateCommand uses shellQuote which prevents expansion
-      const exitCodePath = expandTildeForSSH(`${this.outputDir}/exit_code`);
-      const terminateCmd = buildTerminateCommand(this.pid, exitCodePath);
+      // Pass raw path + expandTildeForSSH to avoid double-quoting
+      // (expandTildeForSSH returns quoted strings, buildTerminateCommand would quote again)
+      const exitCodePath = `${this.outputDir}/exit_code`;
+      const terminateCmd = buildTerminateCommand(this.pid, exitCodePath, expandTildeForSSH);
       await execBuffered(this.sshRuntime, terminateCmd, {
         cwd: "/",
         timeout: 15,

src/node/runtime/backgroundCommands.test.ts

@@ -249,6 +249,23 @@ describe("backgroundCommands", () => {
 
       expect(result).toContain("'/tmp/my dir/exit_code'");
     });
+
+    it("should use custom quotePath function when provided", () => {
+      // Simulate expandTildeForSSH behavior (returns double-quoted string)
+      const customQuote = (p: string) => `"${p}"`;
+      const result = buildTerminateCommand(1234, "/tmp/exit_code", customQuote);
+
+      expect(result).toContain('"/tmp/exit_code"');
+      expect(result).not.toContain("'/tmp/exit_code'");
+    });
+
+    it("should handle tilde paths with custom quotePath", () => {
+      // Simulate expandTildeForSSH("~/mux/exit_code") → "$HOME/mux/exit_code"
+      const expandTilde = (p: string) => (p.startsWith("~/") ? `"$HOME/${p.slice(2)}"` : `"${p}"`);
+      const result = buildTerminateCommand(1234, "~/mux/exit_code", expandTilde);
+
+      expect(result).toContain('"$HOME/mux/exit_code"');
+    });
   });
 
   describe("parseExitCode", () => {

src/node/runtime/backgroundCommands.ts

@@ -116,15 +116,23 @@ export function buildSpawnCommand(options: SpawnCommandOptions): string {
  * Uses negative PID to kill entire process group (setsid makes process a group leader).
  * Sends SIGTERM, waits 2 seconds, then SIGKILL if still running.
  * Writes EXIT_CODE_SIGKILL on force kill.
+ *
+ * @param pid - Process ID to terminate
+ * @param exitCodePath - Path to write exit code (raw, will be quoted by quotePath)
+ * @param quotePath - Function to quote path (default: shellQuote). Use expandTildeForSSH for SSH.
  */
-export function buildTerminateCommand(pid: number, exitCodePath: string): string {
+export function buildTerminateCommand(
+  pid: number,
+  exitCodePath: string,
+  quotePath: (p: string) => string = shellQuote
+): string {
   const pgid = -pid;
   return (
     `kill -TERM ${pgid} 2>/dev/null || true; ` +
     `sleep 2; ` +
     `if kill -0 ${pid} 2>/dev/null; then ` +
     `kill -KILL ${pgid} 2>/dev/null || true; ` +
-    `echo ${EXIT_CODE_SIGKILL} > ${shellQuote(exitCodePath)}; ` +
+    `echo ${EXIT_CODE_SIGKILL} > ${quotePath(exitCodePath)}; ` +
     `fi`
   );
 }