feat(execute_code): add json_parse, shell_quote, retry helpers to sandbox

The execute_code sandbox generates a hermes_tools.py stub module for LLM
scripts. Three common failure modes keep tripping up scripts:

1. json.loads(strict=True) rejects control chars in terminal() output
   (e.g., GitHub issue bodies with literal tabs/newlines)
2. Shell backtick/quote interpretation when interpolating dynamic content
   into terminal() commands (markdown with backticks gets eaten by bash)
3. No retry logic for transient network failures (API timeouts, rate limits)

Adds three convenience helpers to the generated hermes_tools module:

- json_parse(text) — json.loads with strict=False for tolerant parsing
- shell_quote(s) — shlex.quote() for safe shell interpolation
- retry(fn, max_attempts=3, delay=2) — exponential backoff wrapper

Also updates the EXECUTE_CODE_SCHEMA description to document these helpers
so LLMs know they're available without importing anything extra.

Includes 7 new tests (unit + integration) covering all three helpers.

tools/code_execution_tool.py

@@ -137,10 +137,45 @@ def generate_hermes_tools_module(enabled_tools: List[str]) -> str:
 
     header = '''\
 """Auto-generated Hermes tools RPC stubs."""
-import json, os, socket
+import json, os, socket, shlex, time
 
 _sock = None
 
+
+# ---------------------------------------------------------------------------
+# Convenience helpers (avoid common scripting pitfalls)
+# ---------------------------------------------------------------------------
+
+def json_parse(text: str):
+    """Parse JSON tolerant of control characters (strict=False).
+    Use this instead of json.loads() when parsing output from terminal()
+    or web_extract() that may contain raw tabs/newlines in strings."""
+    return json.loads(text, strict=False)
+
+
+def shell_quote(s: str) -> str:
+    """Shell-escape a string for safe interpolation into commands.
+    Use this when inserting dynamic content into terminal() commands:
+        terminal(f"echo {shell_quote(user_input)}")
+    """
+    return shlex.quote(s)
+
+
+def retry(fn, max_attempts=3, delay=2):
+    """Retry a function up to max_attempts times with exponential backoff.
+    Use for transient failures (network errors, API rate limits):
+        result = retry(lambda: terminal("gh issue list ..."))
+    """
+    last_err = None
+    for attempt in range(max_attempts):
+        try:
+            return fn()
+        except Exception as e:
+            last_err = e
+            if attempt < max_attempts - 1:
+                time.sleep(delay * (2 ** attempt))
+    raise last_err
+
 def _connect():
     global _sock
     if _sock is None:
@@ -586,7 +621,11 @@ EXECUTE_CODE_SCHEMA = {
         "Limits: 5-minute timeout, 50KB stdout cap, max 50 tool calls per script. "
         "terminal() is foreground-only (no background or pty).\n\n"
         "Print your final result to stdout. Use Python stdlib (json, re, math, csv, "
-        "datetime, collections, etc.) for processing between tool calls."
+        "datetime, collections, etc.) for processing between tool calls.\n\n"
+        "Also available (no import needed — built into hermes_tools):\n"
+        "  json_parse(text: str) — json.loads with strict=False; use for terminal() output with control chars\n"
+        "  shell_quote(s: str) — shlex.quote(); use when interpolating dynamic strings into shell commands\n"
+        "  retry(fn, max_attempts=3, delay=2) — retry with exponential backoff for transient failures"
     ),
     "parameters": {
         "type": "object",