fix(tasks): bound per-session background work

examples/acp-agent/tests/acp.snapshot.ts

@@ -57,6 +57,9 @@ const WEB_CONFIG = fileURLToPath(new URL('../web.cordis.yml', import.meta.url))
 const FS_SEARCH_CONFIG = fileURLToPath(new URL('./fs-search.cordis.yml', import.meta.url))
 const PARTIAL_LANDLOCK_CONFIG = fileURLToPath(new URL('../partial-landlock.cordis.yml', import.meta.url))
 const PWSH_CONFIG = fileURLToPath(new URL('./pwsh.cordis.yml', import.meta.url))
+const BACKGROUND_TASK_ADMISSION_CONFIG = fileURLToPath(
+  new URL('../background-task-admission.cordis.yml', import.meta.url),
+)
 const PRODUCT_SUBAGENT_CODEX_CONFIG = fileURLToPath(new URL('../product-subagent-codex.cordis.yml', import.meta.url))
 const PRODUCT_SUBAGENT_BOTH_CONFIG = fileURLToPath(new URL('../product-subagent-both.cordis.yml', import.meta.url))
 const FS_DIFF_BOUND_CONFIG = fileURLToPath(new URL('./fs-diff-bound.cordis.yml', import.meta.url))
@@ -215,6 +218,14 @@ const SCENARIOS: Scenario[] = [
     configPath: PTY_CONFIG,
   },
   { name: 'bash-tool-turn', hasModelTurn: true, recorded: true },
+  {
+    name: 'background-task-admission',
+    hasModelTurn: true,
+    recorded: false,
+    overridden: true,
+    configPath: BACKGROUND_TASK_ADMISSION_CONFIG,
+    posixOnly: true,
+  },
   // The pwsh overlay (pwsh.cordis.yml / pwsh.cordis.snapshot.yml) swaps the
   // bundle's bash tool for the PowerShell twin, so its header class pins its
   // own prompt/tool sidecars and a recorded transcript.