refactor(cron): extract _format_timing and _format_state helpers

Addresses review feedback: moves schedule formatting and state
formatting into dedicated static methods, removes duplicate
in-loop imports, and simplifies _list_jobs() to a clean loop.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

nanobot/agent/tools/cron.py

@@ -1,11 +1,12 @@
 """Cron tool for scheduling reminders and tasks."""
 
 from contextvars import ContextVar
+from datetime import datetime, timezone
 from typing import Any
 
 from nanobot.agent.tools.base import Tool
 from nanobot.cron.service import CronService
-from nanobot.cron.types import CronSchedule
+from nanobot.cron.types import CronJobState, CronSchedule
 
 
 class CronTool(Tool):
@@ -143,49 +144,49 @@ class CronTool(Tool):
         )
         return f"Created job '{job.name}' (id: {job.id})"
 
+    @staticmethod
+    def _format_timing(schedule: CronSchedule) -> str:
+        """Format schedule as a human-readable timing string."""
+        if schedule.kind == "cron":
+            tz = f" ({schedule.tz})" if schedule.tz else ""
+            return f"cron: {schedule.expr}{tz}"
+        if schedule.kind == "every" and schedule.every_ms:
+            secs = schedule.every_ms // 1000
+            if secs >= 3600:
+                return f"every {secs // 3600}h"
+            if secs >= 60:
+                return f"every {secs // 60}m"
+            return f"every {secs}s"
+        if schedule.kind == "at" and schedule.at_ms:
+            dt = datetime.fromtimestamp(schedule.at_ms / 1000, tz=timezone.utc)
+            return f"at {dt.isoformat()}"
+        return schedule.kind
+
+    @staticmethod
+    def _format_state(state: CronJobState) -> list[str]:
+        """Format job run state as display lines."""
+        lines: list[str] = []
+        if state.last_run_at_ms:
+            last_dt = datetime.fromtimestamp(state.last_run_at_ms / 1000, tz=timezone.utc)
+            info = f"  Last run: {last_dt.isoformat()} — {state.last_status or 'unknown'}"
+            if state.last_error:
+                info += f" ({state.last_error})"
+            lines.append(info)
+        if state.next_run_at_ms:
+            next_dt = datetime.fromtimestamp(state.next_run_at_ms / 1000, tz=timezone.utc)
+            lines.append(f"  Next run: {next_dt.isoformat()}")
+        return lines
+
     def _list_jobs(self) -> str:
         jobs = self._cron.list_jobs()
         if not jobs:
             return "No scheduled jobs."
         lines = []
         for j in jobs:
-            s = j.schedule
-            if s.kind == "cron":
-                timing = f"cron: {s.expr}"
-                if s.tz:
-                    timing += f" ({s.tz})"
-            elif s.kind == "every" and s.every_ms:
-                secs = s.every_ms // 1000
-                if secs >= 3600:
-                    timing = f"every {secs // 3600}h"
-                elif secs >= 60:
-                    timing = f"every {secs // 60}m"
-                else:
-                    timing = f"every {secs}s"
-            elif s.kind == "at" and s.at_ms:
-                from datetime import datetime, timezone
-
-                dt = datetime.fromtimestamp(s.at_ms / 1000, tz=timezone.utc)
-                timing = f"at {dt.isoformat()}"
-            else:
-                timing = s.kind
+            timing = self._format_timing(j.schedule)
             status = "enabled" if j.enabled else "disabled"
             parts = [f"- {j.name} (id: {j.id}, {timing}, {status})"]
-            if j.state.last_run_at_ms:
-                from datetime import datetime, timezone
-
-                last_dt = datetime.fromtimestamp(j.state.last_run_at_ms / 1000, tz=timezone.utc)
-                last_info = (
-                    f"  Last run: {last_dt.isoformat()} — {j.state.last_status or 'unknown'}"
-                )
-                if j.state.last_error:
-                    last_info += f" ({j.state.last_error})"
-                parts.append(last_info)
-            if j.state.next_run_at_ms:
-                from datetime import datetime, timezone
-
-                next_dt = datetime.fromtimestamp(j.state.next_run_at_ms / 1000, tz=timezone.utc)
-                parts.append(f"  Next run: {next_dt.isoformat()}")
+            parts.extend(self._format_state(j.state))
             lines.append("\n".join(parts))
         return "Scheduled jobs:\n" + "\n".join(lines)