test(sandbox): adapt scenarios to latest master

examples/acp-agent/session-sandbox-root.cordis.snapshot.yml

@@ -1,6 +1,7 @@
 # Keyless replay counterpart of session-sandbox-root.cordis.yml. Patches do not
-# compose across nested includes, so the replay swap and the deliberately
-# distinct sandbox fallback are applied together to the live tree.
+# compose across nested includes, so the replay swap, the recorded model pin,
+# and the deliberately distinct sandbox fallback are applied together to the
+# live tree.
 - id: base
   name: '@cordisjs/plugin-include'
   config:
@@ -9,6 +10,19 @@
       - id: llm-deepseek
         name: '@deepseek-ai/dsh-llm-deepseek'
         disabled: true
+      - id: acp-agent
+        name: '@deepseek-ai/dsh-acp-demo'
+        config:
+          provider: deepseek
+          model: deepseek-v4-flash
+          persistenceRoot: !!js process.env.DSH_SNAPSHOT_SESSIONS_ROOT ?? './.sessions'
+          persistenceCompression: none
+          workspaceContext:
+            maxBytes: 65536
+          persona: |
+            You are a coding assistant powered by the {{model}} model. Your working directory is {{cwd}}. Your bash tool runs under a file sandbox — a `[sandbox: file access denied …]` result is policy, not a command bug.
+
+            Verify your work by running the code or tests. Keep answers brief and factual.
       - id: sandbox
         name: '@deepseek-ai/dsh-sandbox-local'
         config: