prompts: restore tool examples for better model guidance

Commit 54362bf8ee went too far stripping too many JSON examples to guide LLMs.

plugins/_code_execution/prompts/agent.system.tool.code_exe.md

@@ -6,11 +6,17 @@ args:
 - `session`: terminal session id; default `0`
 - `reset`: kill a session before running; `true` or `false`
 rules:
+- place the command or script in `code`
 - use `runtime=output` to poll running work
 - use `input` for interactive terminal prompts
+- if a session is stuck, call again with the same `session` and `reset=true`
+- check dependencies before running code
+- replace placeholder or demo data with real values before execution
+- use `print()` or `console.log()` when you need explicit output
 - do not interleave other tools while waiting
 - ignore framework `[SYSTEM: ...]` info in output
-example:
+examples:
+1 terminal command
 ~~~json
 {
   "thoughts": ["I should run a terminal command in the default session."],
@@ -24,3 +30,31 @@ example:
   }
 }
 ~~~
+
+2 python snippet
+~~~json
+{
+  "thoughts": ["A short Python check is faster than using the shell."],
+  "headline": "Running Python snippet",
+  "tool_name": "code_execution_tool",
+  "tool_args": {
+    "runtime": "python",
+    "session": 0,
+    "reset": false,
+    "code": "import os\nprint(os.getcwd())"
+  }
+}
+~~~
+
+3 wait for running output
+~~~json
+{
+  "thoughts": ["The previous command is still running, so I should poll for output."],
+  "headline": "Waiting for command output",
+  "tool_name": "code_execution_tool",
+  "tool_args": {
+    "runtime": "output",
+    "session": 0
+  }
+}
+~~~