🤖 fix: guard script abort controller

_Generated with `mux`_

Change-Id: I1da3c370a76e61e583b3d266570caf6dcca2f0b6
Signed-off-by: Thomas Kosiewski <tk@coder.com>

Author: ThomasK33

docs/scripts.md

@@ -37,6 +37,7 @@ Scripts run in the workspace directory with full access to project secrets and e
    **Crucial**: The `# Description:` line is what the AI reads to understand the tool. Be descriptive about what the script does and what arguments it accepts.
 
 3. **Make it executable**:
+
    ```bash
    chmod +x .cmux/scripts/deploy
    ```
@@ -54,9 +55,11 @@ Every executable script in `.cmux/scripts/` is automatically registered as a too
 To make your scripts effective AI tools:
 
 1. **Clear Descriptions**: Explicitly state what the script does and what arguments it expects.
+
    ```bash
    # Description: Fetch logs. Requires one argument: the environment name (dev|prod).
    ```
+
 2. **Robustness**: Use `set -euo pipefail` to ensure the script fails loudly if something goes wrong, allowing the AI to catch the error.
 3. **Feedback**: Use `MUX_PROMPT` to guide the AI on what to do next if the script succeeds or fails (see below).
 

src/node/services/agentSession.ts

@@ -512,8 +512,14 @@ export class AgentSession {
   }
 
   public startScriptExecution(): AbortSignal {
-    this.scriptAbortController = new AbortController();
-    return this.scriptAbortController.signal;
+    assert(
+      this.scriptAbortController === null,
+      "AgentSession.startScriptExecution called while script is running"
+    );
+
+    const abortController = new AbortController();
+    this.scriptAbortController = abortController;
+    return abortController.signal;
   }
 
   public endScriptExecution(): void {