fix(cron): improve timezone scheduling and tz propagation

nanobot/agent/tools/cron.py

@@ -50,6 +50,10 @@ class CronTool(Tool):
                     "type": "string",
                     "description": "Cron expression like '0 9 * * *' (for scheduled tasks)"
                 },
+                "tz": {
+                    "type": "string",
+                    "description": "IANA timezone for cron expressions (e.g. 'America/Vancouver')"
+                },
                 "at": {
                     "type": "string",
                     "description": "ISO datetime for one-time execution (e.g. '2026-02-12T10:30:00')"
@@ -68,30 +72,40 @@ class CronTool(Tool):
         message: str = "",
         every_seconds: int | None = None,
         cron_expr: str | None = None,
+        tz: str | None = None,
         at: str | None = None,
         job_id: str | None = None,
         **kwargs: Any
     ) -> str:
         if action == "add":
-            return self._add_job(message, every_seconds, cron_expr, at)
+            return self._add_job(message, every_seconds, cron_expr, tz, at)
         elif action == "list":
             return self._list_jobs()
         elif action == "remove":
             return self._remove_job(job_id)
         return f"Unknown action: {action}"
     
-    def _add_job(self, message: str, every_seconds: int | None, cron_expr: str | None, at: str | None) -> str:
+    def _add_job(
+        self,
+        message: str,
+        every_seconds: int | None,
+        cron_expr: str | None,
+        tz: str | None,
+        at: str | None,
+    ) -> str:
         if not message:
             return "Error: message is required for add"
         if not self._channel or not self._chat_id:
             return "Error: no session context (channel/chat_id)"
+        if tz and not cron_expr:
+            return "Error: tz can only be used with cron_expr"
         
         # Build schedule
         delete_after = False
         if every_seconds:
             schedule = CronSchedule(kind="every", every_ms=every_seconds * 1000)
         elif cron_expr:
-            schedule = CronSchedule(kind="cron", expr=cron_expr)
+            schedule = CronSchedule(kind="cron", expr=cron_expr, tz=tz)
         elif at:
             from datetime import datetime
             dt = datetime.fromisoformat(at)

nanobot/cli/commands.py

@@ -719,21 +719,32 @@ def cron_list(
     table.add_column("Status")
     table.add_column("Next Run")
     
+    import datetime
     import time
+    from zoneinfo import ZoneInfo
     for job in jobs:
         # Format schedule
         if job.schedule.kind == "every":
             sched = f"every {(job.schedule.every_ms or 0) // 1000}s"
         elif job.schedule.kind == "cron":
             sched = job.schedule.expr or ""
+            if job.schedule.tz:
+                sched = f"{sched} ({job.schedule.tz})"
         else:
             sched = "one-time"
         
         # Format next run
         next_run = ""
         if job.state.next_run_at_ms:
-            next_time = time.strftime("%Y-%m-%d %H:%M", time.localtime(job.state.next_run_at_ms / 1000))
-            next_run = next_time
+            ts = job.state.next_run_at_ms / 1000
+            if job.schedule.kind == "cron" and job.schedule.tz:
+                try:
+                    dt = datetime.fromtimestamp(ts, ZoneInfo(job.schedule.tz))
+                    next_run = dt.strftime("%Y-%m-%d %H:%M")
+                except Exception:
+                    next_run = time.strftime("%Y-%m-%d %H:%M", time.localtime(ts))
+            else:
+                next_run = time.strftime("%Y-%m-%d %H:%M", time.localtime(ts))
         
         status = "[green]enabled[/green]" if job.enabled else "[dim]disabled[/dim]"
         
@@ -748,6 +759,7 @@ def cron_add(
     message: str = typer.Option(..., "--message", "-m", help="Message for agent"),
     every: int = typer.Option(None, "--every", "-e", help="Run every N seconds"),
     cron_expr: str = typer.Option(None, "--cron", "-c", help="Cron expression (e.g. '0 9 * * *')"),
+    tz: str | None = typer.Option(None, "--tz", help="IANA timezone for cron (e.g. 'America/Vancouver')"),
     at: str = typer.Option(None, "--at", help="Run once at time (ISO format)"),
     deliver: bool = typer.Option(False, "--deliver", "-d", help="Deliver response to channel"),
     to: str = typer.Option(None, "--to", help="Recipient for delivery"),
@@ -758,11 +770,15 @@ def cron_add(
     from nanobot.cron.service import CronService
     from nanobot.cron.types import CronSchedule
     
+    if tz and not cron_expr:
+        console.print("[red]Error: --tz can only be used with --cron[/red]")
+        raise typer.Exit(1)
+
     # Determine schedule type
     if every:
         schedule = CronSchedule(kind="every", every_ms=every * 1000)
     elif cron_expr:
-        schedule = CronSchedule(kind="cron", expr=cron_expr)
+        schedule = CronSchedule(kind="cron", expr=cron_expr, tz=tz)
     elif at:
         import datetime
         dt = datetime.datetime.fromisoformat(at)

nanobot/cron/service.py

@@ -32,7 +32,8 @@ def _compute_next_run(schedule: CronSchedule, now_ms: int) -> int | None:
         try:
             from croniter import croniter
             from zoneinfo import ZoneInfo
-            base_time = time.time()
+            # Use the caller-provided reference time for deterministic scheduling.
+            base_time = now_ms / 1000
             tz = ZoneInfo(schedule.tz) if schedule.tz else datetime.now().astimezone().tzinfo
             base_dt = datetime.fromtimestamp(base_time, tz=tz)
             cron = croniter(schedule.expr, base_dt)