🤖 fix: correctly detect signal-killed processes in isRunning()

- Check both exitCode and signalCode when determining if process is alive
- Fixes terminate() always sending SIGKILL after SIGTERM, even when process
  already stopped (signal-killed processes have signalCode set but exitCode null)
- Also gate background tools for SSH runtimes (TODO: replace duck-type check
  with proper capability flag once SSH implements spawnBackground)

Author: ethanndickson

src/common/utils/tools/tools.ts

@@ -110,9 +110,12 @@ export async function getToolsForModel(
     web_fetch: wrap(createWebFetchTool(config)),
   };
 
-  // Only include background tools when manager is available
-  // (not available in CLI/debug paths)
-  if (config.backgroundProcessManager) {
+  // Only include background tools when manager is available and runtime supports it
+  // (not available in CLI/debug paths, and SSH runtimes don't support background execution yet)
+  // TODO: Replace this duck-type check with a proper runtime.supportsBackgroundExecution capability
+  // once SSHRuntime implements spawnBackground()
+  const isSSHRuntime = "getConfig" in config.runtime;
+  if (config.backgroundProcessManager && !isSSHRuntime) {
     runtimeTools.bash_background_read = wrap(createBashBackgroundReadTool(config));
     runtimeTools.bash_background_list = wrap(createBashBackgroundListTool(config));
     runtimeTools.bash_background_terminate = wrap(createBashBackgroundTerminateTool(config));

src/node/runtime/LocalBackgroundHandle.ts

@@ -76,7 +76,10 @@ export class LocalBackgroundHandle implements BackgroundHandle {
   }
 
   isRunning(): Promise<boolean> {
-    return Promise.resolve(this.disposable.underlying.exitCode === null);
+    const child = this.disposable.underlying;
+    // Process is dead if either exitCode or signalCode is set
+    // (signal-killed processes have signalCode set but exitCode remains null)
+    return Promise.resolve(child.exitCode === null && child.signalCode === null);
   }
 
   async terminate(): Promise<void> {