fix(session): add semantic crash checkpoints

packages/bash/tool-bash/src/index.ts

@@ -440,6 +440,10 @@ export function apply(ctx: Context, config: Config = {}): void {
         })
         return [{ type: 'text', text: `started background task ${id}` }]
       }
+      // A durability or policy wrapper may yield before dispatch. Normalize a
+      // cancellation that arrived during that boundary before the executor can
+      // expose its backend-specific pre-spawn error.
+      if (exec.signal?.aborted) throw new Error('command aborted')
       const result = await ctx.bash.run(ctx.bash.resolve({
         ...request,
         ...exec.signal ? { signal: exec.signal } : {},