diff --git a/.gitignore b/.gitignore
index 9397a220..17bdb86d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,8 +4,9 @@
 .env.*
 !.env.example
 
-# Claude Code worktrees
+# Claude Code worktrees and lock files
 .claude/worktrees/
+.claude/scheduled_tasks.lock
 
 # Sidecar tool data
 .sidecar/
diff --git a/Cargo.lock b/Cargo.lock
index c6ad733a..31998df0 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -864,6 +864,16 @@ dependencies = [
  "windows-link",
 ]
 
+[[package]]
+name = "chrono-tz"
+version = "0.10.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a6139a8597ed92cf816dfb33f5dd6cf0bb93a6adc938f11039f371bc5bcd26c3"
+dependencies = [
+ "chrono",
+ "phf 0.12.1",
+]
+
 [[package]]
 name = "cipher"
 version = "0.4.4"
@@ -2872,6 +2882,7 @@ dependencies = [
  "bollard",
  "bytes",
  "chrono",
+ "chrono-tz",
  "clap",
  "clap_complete",
  "cron",
@@ -2890,6 +2901,7 @@ dependencies = [
  "http-body-util",
  "hyper 1.8.1",
  "hyper-util",
+ "iana-time-zone",
  "insta",
  "libsql",
  "lru",
@@ -3892,6 +3904,15 @@ dependencies = [
  "phf_shared 0.11.3",
 ]
 
+[[package]]
+name = "phf"
+version = "0.12.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "913273894cec178f401a31ec4b656318d95473527be05c0752cc41cdc32be8b7"
+dependencies = [
+ "phf_shared 0.12.1",
+]
+
 [[package]]
 name = "phf"
 version = "0.13.1"
@@ -3966,6 +3987,15 @@ dependencies = [
  "uncased",
 ]
 
+[[package]]
+name = "phf_shared"
+version = "0.12.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "06005508882fb681fd97892ecff4b7fd0fee13ef1aa569f8695dae7ab9099981"
+dependencies = [
+ "siphasher",
+]
+
 [[package]]
 name = "phf_shared"
 version = "0.13.1"
diff --git a/Cargo.toml b/Cargo.toml
index 75d42f63..6747bbd0 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -73,6 +73,8 @@ toml = "0.8"
 # Core types
 uuid = { version = "1", features = ["v4", "v5", "serde"] }
 chrono = { version = "0.4", features = ["serde"] }
+chrono-tz = "0.10"
+iana-time-zone = "0.1"
 rust_decimal = { version = "1", features = ["serde", "serde-with-str", "maths"] }
 rust_decimal_macros = "1"
 
diff --git a/src/agent/agent_loop.rs b/src/agent/agent_loop.rs
index f76afc75..0e6f508c 100644
--- a/src/agent/agent_loop.rs
+++ b/src/agent/agent_loop.rs
@@ -356,6 +356,12 @@ impl Agent {
                 if let Some(workspace) = self.workspace() {
                     let mut config = AgentHeartbeatConfig::default()
                         .with_interval(std::time::Duration::from_secs(hb_config.interval_secs));
+                    config.quiet_hours_start = hb_config.quiet_hours_start;
+                    config.quiet_hours_end = hb_config.quiet_hours_end;
+                    config.timezone = hb_config
+                        .timezone
+                        .clone()
+                        .or_else(|| Some(self.config.default_timezone.clone()));
                     if let (Some(user), Some(channel)) =
                         (&hb_config.notify_user, &hb_config.notify_channel)
                     {
diff --git a/src/agent/dispatcher.rs b/src/agent/dispatcher.rs
index 2834777a..85c24763 100644
--- a/src/agent/dispatcher.rs
+++ b/src/agent/dispatcher.rs
@@ -50,8 +50,18 @@ impl Agent {
 
         // Load workspace system prompt (identity files: AGENTS.md, SOUL.md, etc.)
         // In group chats, MEMORY.md is excluded to prevent leaking personal context.
+        // Resolve the user's timezone
+        let user_tz = crate::timezone::resolve_timezone(
+            message.timezone.as_deref(),
+            None, // user setting lookup can be added later
+            &self.config.default_timezone,
+        );
+
         let system_prompt = if let Some(ws) = self.workspace() {
-            match ws.system_prompt_for_context(is_group_chat).await {
+            match ws
+                .system_prompt_for_context_tz(is_group_chat, user_tz)
+                .await
+            {
                 Ok(prompt) if !prompt.is_empty() => Some(prompt),
                 Ok(_) => None,
                 Err(e) => {
@@ -130,6 +140,7 @@ impl Agent {
         let mut job_ctx =
             JobContext::with_user(&message.user_id, "chat", "Interactive chat session");
         job_ctx.http_interceptor = self.deps.http_interceptor.clone();
+        job_ctx.user_timezone = user_tz.name().to_string();
 
         // Build system prompts once for this turn. Two variants: with tools
         // (normal iterations) and without (force_text final iteration).
@@ -785,6 +796,7 @@ impl Agent {
                             tool_call_id: tc.id.clone(),
                             context_messages: context_messages.clone(),
                             deferred_tool_calls: tool_calls[approval_idx + 1..].to_vec(),
+                            user_timezone: Some(user_tz.name().to_string()),
                         };
 
                         return Ok(AgenticLoopResult::NeedApproval { pending });
@@ -1146,6 +1158,7 @@ mod tests {
                 max_actions_per_hour: None,
                 max_tool_iterations: 50,
                 auto_approve_tools: false,
+                default_timezone: "UTC".to_string(),
             },
             deps,
             Arc::new(ChannelManager::new()),
@@ -1248,6 +1261,7 @@ mod tests {
                     arguments: serde_json::json!({"message": "done"}),
                 },
             ],
+            user_timezone: None,
         };
 
         let json = serde_json::to_string(&pending).expect("serialize");
@@ -1900,6 +1914,7 @@ mod tests {
                 max_actions_per_hour: None,
                 max_tool_iterations,
                 auto_approve_tools: true,
+                default_timezone: "UTC".to_string(),
             },
             deps,
             Arc::new(ChannelManager::new()),
@@ -2015,6 +2030,7 @@ mod tests {
                     max_actions_per_hour: None,
                     max_tool_iterations: max_iter,
                     auto_approve_tools: true,
+                    default_timezone: "UTC".to_string(),
                 },
                 deps,
                 Arc::new(ChannelManager::new()),
diff --git a/src/agent/heartbeat.rs b/src/agent/heartbeat.rs
index a034a1a1..5c99d01e 100644
--- a/src/agent/heartbeat.rs
+++ b/src/agent/heartbeat.rs
@@ -48,6 +48,12 @@ pub struct HeartbeatConfig {
     pub notify_user_id: Option<String>,
     /// Channel to notify on heartbeat findings.
     pub notify_channel: Option<String>,
+    /// Hour (0-23) when quiet hours start.
+    pub quiet_hours_start: Option<u32>,
+    /// Hour (0-23) when quiet hours end.
+    pub quiet_hours_end: Option<u32>,
+    /// Timezone for quiet hours evaluation (IANA name).
+    pub timezone: Option<String>,
 }
 
 impl Default for HeartbeatConfig {
@@ -58,6 +64,9 @@ impl Default for HeartbeatConfig {
             max_failures: 3,
             notify_user_id: None,
             notify_channel: None,
+            quiet_hours_start: None,
+            quiet_hours_end: None,
+            timezone: None,
         }
     }
 }
@@ -75,6 +84,26 @@ impl HeartbeatConfig {
         self
     }
 
+    /// Check whether the current time falls within configured quiet hours.
+    pub fn is_quiet_hours(&self) -> bool {
+        use chrono::Timelike;
+        let (Some(start), Some(end)) = (self.quiet_hours_start, self.quiet_hours_end) else {
+            return false;
+        };
+        let tz = self
+            .timezone
+            .as_deref()
+            .and_then(crate::timezone::parse_timezone)
+            .unwrap_or(chrono_tz::UTC);
+        let now_hour = crate::timezone::now_in_tz(tz).hour();
+        if start <= end {
+            now_hour >= start && now_hour < end
+        } else {
+            // Wraps midnight, e.g. 22..06
+            now_hour >= start || now_hour < end
+        }
+    }
+
     /// Set the notification target.
     pub fn with_notify(mut self, user_id: impl Into<String>, channel: impl Into<String>) -> Self {
         self.notify_user_id = Some(user_id.into());
@@ -162,6 +191,12 @@ impl HeartbeatRunner {
         loop {
             interval.tick().await;
 
+            // Skip during quiet hours
+            if self.config.is_quiet_hours() {
+                tracing::debug!("Heartbeat skipped: quiet hours");
+                continue;
+            }
+
             // Run memory hygiene in the background so it never delays the
             // heartbeat checklist. Failures are logged inside run_if_due.
             let hygiene_workspace = Arc::clone(&self.workspace);
@@ -532,6 +567,83 @@ mod tests {
         assert!(!is_effectively_empty(content));
     }
 
+    // ==================== quiet hours ====================
+
+    #[test]
+    fn test_quiet_hours_inside() {
+        use chrono::{Timelike, Utc};
+
+        let now_utc = Utc::now();
+        let hour = now_utc.hour();
+        let start = hour;
+        let end = (hour + 1) % 24;
+
+        let config = HeartbeatConfig {
+            quiet_hours_start: Some(start),
+            quiet_hours_end: Some(end),
+            timezone: Some("UTC".to_string()),
+            ..HeartbeatConfig::default()
+        };
+        // Current UTC hour is inside [start, end) by construction
+        assert!(config.is_quiet_hours());
+    }
+
+    #[test]
+    fn test_quiet_hours_outside() {
+        use chrono::{Timelike, Utc};
+
+        let now_utc = Utc::now();
+        let hour = now_utc.hour();
+        let start = (hour + 1) % 24;
+        let end = (hour + 2) % 24;
+
+        let config = HeartbeatConfig {
+            quiet_hours_start: Some(start),
+            quiet_hours_end: Some(end),
+            timezone: Some("UTC".to_string()),
+            ..HeartbeatConfig::default()
+        };
+        // Current UTC hour is outside [start, end) by construction
+        assert!(!config.is_quiet_hours());
+    }
+
+    #[test]
+    fn test_quiet_hours_wraparound_excludes_now() {
+        use chrono::{Timelike, Utc};
+
+        let now_utc = Utc::now();
+        let hour = now_utc.hour();
+        // Window covers all hours except the current one
+        let start = (hour + 1) % 24;
+        let end = hour;
+
+        let config = HeartbeatConfig {
+            quiet_hours_start: Some(start),
+            quiet_hours_end: Some(end),
+            timezone: Some("UTC".to_string()),
+            ..HeartbeatConfig::default()
+        };
+        assert!(!config.is_quiet_hours());
+    }
+
+    #[test]
+    fn test_quiet_hours_none_configured() {
+        let config = HeartbeatConfig::default();
+        assert!(!config.is_quiet_hours());
+    }
+
+    #[test]
+    fn test_quiet_hours_same_start_end() {
+        let config = HeartbeatConfig {
+            quiet_hours_start: Some(10),
+            quiet_hours_end: Some(10),
+            timezone: Some("UTC".to_string()),
+            ..HeartbeatConfig::default()
+        };
+        // start == end means zero-width window, should be false
+        assert!(!config.is_quiet_hours());
+    }
+
     #[test]
     fn test_spawn_heartbeat_accepts_store_param() {
         // Regression: spawn_heartbeat must accept an optional Database store
diff --git a/src/agent/routine.rs b/src/agent/routine.rs
index 4cf691be..fdd61012 100644
--- a/src/agent/routine.rs
+++ b/src/agent/routine.rs
@@ -57,7 +57,11 @@ pub struct Routine {
 #[serde(tag = "type", rename_all = "snake_case")]
 pub enum Trigger {
     /// Fire on a cron schedule (e.g. "0 9 * * MON-FRI" or "every 2h").
-    Cron { schedule: String },
+    Cron {
+        schedule: String,
+        #[serde(default)]
+        timezone: Option<String>,
+    },
     /// Fire when a channel message matches a pattern.
     Event {
         /// Optional channel filter (e.g. "telegram", "slack").
@@ -99,7 +103,21 @@ impl Trigger {
                         field: "schedule".into(),
                     })?
                     .to_string();
-                Ok(Trigger::Cron { schedule })
+                let timezone = config
+                    .get("timezone")
+                    .and_then(|v| v.as_str())
+                    .and_then(|tz| {
+                        if crate::timezone::parse_timezone(tz).is_some() {
+                            Some(tz.to_string())
+                        } else {
+                            tracing::warn!(
+                                "Ignoring invalid timezone '{}' from DB for cron trigger",
+                                tz
+                            );
+                            None
+                        }
+                    });
+                Ok(Trigger::Cron { schedule, timezone })
             }
             "event" => {
                 let pattern = config
@@ -137,7 +155,10 @@ impl Trigger {
     /// Serialize trigger-specific config to JSON for DB storage.
     pub fn to_config_json(&self) -> serde_json::Value {
         match self {
-            Trigger::Cron { schedule } => serde_json::json!({ "schedule": schedule }),
+            Trigger::Cron { schedule, timezone } => serde_json::json!({
+                "schedule": schedule,
+                "timezone": timezone,
+            }),
             Trigger::Event { channel, pattern } => serde_json::json!({
                 "pattern": pattern,
                 "channel": channel,
@@ -415,12 +436,25 @@ pub fn content_hash(content: &str) -> u64 {
 }
 
 /// Parse a cron expression and compute the next fire time from now.
-pub fn next_cron_fire(schedule: &str) -> Result<Option<DateTime<Utc>>, RoutineError> {
+///
+/// When `timezone` is provided and valid, the schedule is evaluated in that
+/// timezone and the result is converted back to UTC. Otherwise UTC is used.
+pub fn next_cron_fire(
+    schedule: &str,
+    timezone: Option<&str>,
+) -> Result<Option<DateTime<Utc>>, RoutineError> {
     let cron_schedule =
         cron::Schedule::from_str(schedule).map_err(|e| RoutineError::InvalidCron {
             reason: e.to_string(),
         })?;
-    Ok(cron_schedule.upcoming(Utc).next())
+    if let Some(tz) = timezone.and_then(crate::timezone::parse_timezone) {
+        Ok(cron_schedule
+            .upcoming(tz)
+            .next()
+            .map(|dt| dt.with_timezone(&Utc)))
+    } else {
+        Ok(cron_schedule.upcoming(Utc).next())
+    }
 }
 
 #[cfg(test)]
@@ -433,10 +467,11 @@ mod tests {
     fn test_trigger_roundtrip() {
         let trigger = Trigger::Cron {
             schedule: "0 9 * * MON-FRI".to_string(),
+            timezone: None,
         };
         let json = trigger.to_config_json();
         let parsed = Trigger::from_db("cron", json).expect("parse cron");
-        assert!(matches!(parsed, Trigger::Cron { schedule } if schedule == "0 9 * * MON-FRI"));
+        assert!(matches!(parsed, Trigger::Cron { schedule, .. } if schedule == "0 9 * * MON-FRI"));
     }
 
     #[test]
@@ -509,16 +544,58 @@ mod tests {
     #[test]
     fn test_next_cron_fire_valid() {
         // Every minute should always have a next fire
-        let next = next_cron_fire("* * * * * *").expect("valid cron");
+        let next = next_cron_fire("* * * * * *", None).expect("valid cron");
         assert!(next.is_some());
     }
 
     #[test]
     fn test_next_cron_fire_invalid() {
-        let result = next_cron_fire("not a cron");
+        let result = next_cron_fire("not a cron", None);
         assert!(result.is_err());
     }
 
+    #[test]
+    fn test_trigger_cron_timezone_roundtrip() {
+        let trigger = Trigger::Cron {
+            schedule: "0 9 * * MON-FRI".to_string(),
+            timezone: Some("America/New_York".to_string()),
+        };
+        let json = trigger.to_config_json();
+        let parsed = Trigger::from_db("cron", json).expect("parse cron");
+        assert!(matches!(parsed, Trigger::Cron { schedule, timezone }
+                if schedule == "0 9 * * MON-FRI"
+                && timezone.as_deref() == Some("America/New_York")));
+    }
+
+    #[test]
+    fn test_trigger_cron_no_timezone_backward_compat() {
+        let json = serde_json::json!({"schedule": "0 9 * * *"});
+        let parsed = Trigger::from_db("cron", json).expect("parse cron");
+        assert!(matches!(parsed, Trigger::Cron { timezone, .. } if timezone.is_none()));
+    }
+
+    #[test]
+    fn test_trigger_cron_invalid_timezone_coerced_to_none() {
+        let json = serde_json::json!({"schedule": "0 9 * * *", "timezone": "Fake/Zone"});
+        let parsed = Trigger::from_db("cron", json).expect("parse cron");
+        assert!(
+            matches!(parsed, Trigger::Cron { timezone, .. } if timezone.is_none()),
+            "invalid timezone should be coerced to None"
+        );
+    }
+
+    #[test]
+    fn test_next_cron_fire_with_timezone() {
+        let next_utc = next_cron_fire("0 0 9 * * * *", None)
+            .expect("valid cron")
+            .expect("has next");
+        let next_est = next_cron_fire("0 0 9 * * * *", Some("America/New_York"))
+            .expect("valid cron")
+            .expect("has next");
+        // EST is UTC-5 (or EDT UTC-4), so the UTC result should differ
+        assert_ne!(next_utc, next_est, "timezone should shift the fire time");
+    }
+
     #[test]
     fn test_guardrails_default() {
         let g = RoutineGuardrails::default();
@@ -531,7 +608,8 @@ mod tests {
     fn test_trigger_type_tag() {
         assert_eq!(
             Trigger::Cron {
-                schedule: String::new()
+                schedule: String::new(),
+                timezone: None,
             }
             .type_tag(),
             "cron"
diff --git a/src/agent/routine_engine.rs b/src/agent/routine_engine.rs
index da22ffc1..fe2b95d5 100644
--- a/src/agent/routine_engine.rs
+++ b/src/agent/routine_engine.rs
@@ -170,7 +170,7 @@ impl RoutineEngine {
                 continue;
             }
 
-            let detail = if let Trigger::Cron { ref schedule } = routine.trigger {
+            let detail = if let Trigger::Cron { ref schedule, .. } = routine.trigger {
                 Some(schedule.clone())
             } else {
                 None
@@ -380,8 +380,12 @@ async fn execute_routine(ctx: EngineContext, routine: Routine, run: RoutineRun)
 
     // Update routine runtime state
     let now = Utc::now();
-    let next_fire = if let Trigger::Cron { ref schedule } = routine.trigger {
-        next_cron_fire(schedule).unwrap_or(None)
+    let next_fire = if let Trigger::Cron {
+        ref schedule,
+        ref timezone,
+    } = routine.trigger
+    {
+        next_cron_fire(schedule, timezone.as_deref()).unwrap_or(None)
     } else {
         None
     };
diff --git a/src/agent/session.rs b/src/agent/session.rs
index 5dee8b47..a051ffea 100644
--- a/src/agent/session.rs
+++ b/src/agent/session.rs
@@ -164,6 +164,10 @@ pub struct PendingApproval {
     /// executed yet when approval was requested.
     #[serde(default)]
     pub deferred_tool_calls: Vec<ToolCall>,
+    /// User timezone at the time the approval was requested, so it persists
+    /// through the approval flow even if the approval message lacks timezone.
+    #[serde(default)]
+    pub user_timezone: Option<String>,
 }
 
 /// A conversation thread within a session.
@@ -976,6 +980,7 @@ mod tests {
             tool_call_id: "call_123".to_string(),
             context_messages: vec![ChatMessage::user("do it")],
             deferred_tool_calls: vec![],
+            user_timezone: None,
         };
 
         thread.await_approval(approval);
@@ -1001,6 +1006,7 @@ mod tests {
             tool_call_id: "call_456".to_string(),
             context_messages: vec![],
             deferred_tool_calls: vec![],
+            user_timezone: None,
         };
 
         thread.await_approval(approval);
diff --git a/src/agent/thread_ops.rs b/src/agent/thread_ops.rs
index 954c0f02..a2001e4c 100644
--- a/src/agent/thread_ops.rs
+++ b/src/agent/thread_ops.rs
@@ -746,6 +746,16 @@ impl Agent {
             let mut job_ctx =
                 JobContext::with_user(&message.user_id, "chat", "Interactive chat session");
             job_ctx.http_interceptor = self.deps.http_interceptor.clone();
+            // Prefer a valid timezone from the approval message, fall back to the
+            // resolved timezone stored when the approval was originally requested.
+            let tz_candidate = message
+                .timezone
+                .as_deref()
+                .filter(|tz| crate::timezone::parse_timezone(tz).is_some())
+                .or(pending.user_timezone.as_deref());
+            if let Some(tz) = tz_candidate {
+                job_ctx.user_timezone = tz.to_string();
+            }
 
             let _ = self
                 .channels
@@ -1111,6 +1121,8 @@ impl Agent {
                     tool_call_id: tc.id.clone(),
                     context_messages: context_messages.clone(),
                     deferred_tool_calls: deferred_tool_calls[approval_idx + 1..].to_vec(),
+                    // Carry forward the resolved timezone from the original pending approval
+                    user_timezone: pending.user_timezone.clone(),
                 };
 
                 let request_id = new_pending.request_id;
diff --git a/src/channels/channel.rs b/src/channels/channel.rs
index 1160c411..3ab5c1f6 100644
--- a/src/channels/channel.rs
+++ b/src/channels/channel.rs
@@ -79,6 +79,8 @@ pub struct IncomingMessage {
     pub received_at: DateTime<Utc>,
     /// Channel-specific metadata.
     pub metadata: serde_json::Value,
+    /// IANA timezone string from the client (e.g. "America/New_York").
+    pub timezone: Option<String>,
     /// File or media attachments on this message.
     pub attachments: Vec<IncomingAttachment>,
 }
@@ -99,6 +101,7 @@ impl IncomingMessage {
             thread_id: None,
             received_at: Utc::now(),
             metadata: serde_json::Value::Null,
+            timezone: None,
             attachments: Vec::new(),
         }
     }
@@ -121,6 +124,12 @@ impl IncomingMessage {
         self
     }
 
+    /// Set the client timezone.
+    pub fn with_timezone(mut self, tz: impl Into<String>) -> Self {
+        self.timezone = Some(tz.into());
+        self
+    }
+
     /// Set attachments.
     pub fn with_attachments(mut self, attachments: Vec<IncomingAttachment>) -> Self {
         self.attachments = attachments;
@@ -454,4 +463,10 @@ mod tests {
             panic!("expected ToolCompleted variant");
         }
     }
+
+    #[test]
+    fn test_incoming_message_with_timezone() {
+        let msg = IncomingMessage::new("test", "user1", "hello").with_timezone("America/New_York");
+        assert_eq!(msg.timezone.as_deref(), Some("America/New_York"));
+    }
 }
diff --git a/src/channels/repl.rs b/src/channels/repl.rs
index f4cc7d3f..9031aa4e 100644
--- a/src/channels/repl.rs
+++ b/src/channels/repl.rs
@@ -297,9 +297,11 @@ impl Channel for ReplChannel {
         let esc_interrupt_triggered_for_thread = Arc::new(AtomicBool::new(false));
 
         std::thread::spawn(move || {
+            let sys_tz = crate::timezone::detect_system_timezone().name().to_string();
+
             // Single message mode: send it and return
             if let Some(msg) = single_message {
-                let incoming = IncomingMessage::new("repl", "default", &msg);
+                let incoming = IncomingMessage::new("repl", "default", &msg).with_timezone(&sys_tz);
                 let _ = tx.blocking_send(incoming);
                 return;
             }
@@ -361,7 +363,8 @@ impl Channel for ReplChannel {
                             "/quit" | "/exit" => {
                                 // Forward shutdown command so the agent loop exits even
                                 // when other channels (e.g. web gateway) are still active.
-                                let msg = IncomingMessage::new("repl", "default", "/quit");
+                                let msg = IncomingMessage::new("repl", "default", "/quit")
+                                    .with_timezone(&sys_tz);
                                 let _ = tx.blocking_send(msg);
                                 break;
                             }
@@ -382,7 +385,8 @@ impl Channel for ReplChannel {
                             _ => {}
                         }
 
-                        let msg = IncomingMessage::new("repl", "default", line);
+                        let msg =
+                            IncomingMessage::new("repl", "default", line).with_timezone(&sys_tz);
                         if tx.blocking_send(msg).is_err() {
                             break;
                         }
@@ -390,20 +394,23 @@ impl Channel for ReplChannel {
                     Err(ReadlineError::Interrupted) => {
                         if esc_interrupt_triggered_for_thread.swap(false, Ordering::Relaxed) {
                             // Esc: interrupt current operation and keep REPL open.
-                            let msg = IncomingMessage::new("repl", "default", "/interrupt");
+                            let msg = IncomingMessage::new("repl", "default", "/interrupt")
+                                .with_timezone(&sys_tz);
                             if tx.blocking_send(msg).is_err() {
                                 break;
                             }
                         } else {
                             // Ctrl+C (VINTR): request graceful shutdown.
-                            let msg = IncomingMessage::new("repl", "default", "/quit");
+                            let msg = IncomingMessage::new("repl", "default", "/quit")
+                                .with_timezone(&sys_tz);
                             let _ = tx.blocking_send(msg);
                             break;
                         }
                     }
                     Err(ReadlineError::Eof) => {
                         // Ctrl+D: send /quit so the agent loop runs graceful shutdown
-                        let msg = IncomingMessage::new("repl", "default", "/quit");
+                        let msg =
+                            IncomingMessage::new("repl", "default", "/quit").with_timezone(&sys_tz);
                         let _ = tx.blocking_send(msg);
                         break;
                     }
diff --git a/src/channels/web/handlers/routines.rs b/src/channels/web/handlers/routines.rs
index 88abfc68..d7c4f764 100644
--- a/src/channels/web/handlers/routines.rs
+++ b/src/channels/web/handlers/routines.rs
@@ -264,7 +264,7 @@ pub async fn routines_runs_handler(
 /// Convert a Routine to the trimmed RoutineInfo for list display.
 fn routine_to_info(r: &crate::agent::routine::Routine) -> RoutineInfo {
     let (trigger_type, trigger_summary) = match &r.trigger {
-        crate::agent::routine::Trigger::Cron { schedule } => {
+        crate::agent::routine::Trigger::Cron { schedule, .. } => {
             ("cron".to_string(), format!("cron: {}", schedule))
         }
         crate::agent::routine::Trigger::Event {
diff --git a/src/channels/web/server.rs b/src/channels/web/server.rs
index 2f3b2a5b..1c6e7f85 100644
--- a/src/channels/web/server.rs
+++ b/src/channels/web/server.rs
@@ -610,6 +610,7 @@ async fn oauth_callback_handler(
 
 async fn chat_send_handler(
     State(state): State<Arc<GatewayState>>,
+    headers: axum::http::HeaderMap,
     Json(req): Json<SendMessageRequest>,
 ) -> Result<(StatusCode, Json<SendMessageResponse>), (StatusCode, String)> {
     tracing::debug!(
@@ -626,6 +627,14 @@ async fn chat_send_handler(
     }
 
     let mut msg = IncomingMessage::new("gateway", &state.user_id, &req.content);
+    // Prefer timezone from JSON body, fall back to X-Timezone header
+    let tz = req
+        .timezone
+        .as_deref()
+        .or_else(|| headers.get("X-Timezone").and_then(|v| v.to_str().ok()));
+    if let Some(tz) = tz {
+        msg = msg.with_timezone(tz);
+    }
 
     if let Some(ref thread_id) = req.thread_id {
         msg = msg.with_thread(thread_id);
@@ -2115,7 +2124,7 @@ async fn routines_runs_handler(
 /// Convert a Routine to the trimmed RoutineInfo for list display.
 fn routine_to_info(r: &crate::agent::routine::Routine) -> RoutineInfo {
     let (trigger_type, trigger_summary) = match &r.trigger {
-        crate::agent::routine::Trigger::Cron { schedule } => {
+        crate::agent::routine::Trigger::Cron { schedule, .. } => {
             ("cron".to_string(), format!("cron: {}", schedule))
         }
         crate::agent::routine::Trigger::Event {
diff --git a/src/channels/web/static/app.js b/src/channels/web/static/app.js
index 1513c418..68b803f9 100644
--- a/src/channels/web/static/app.js
+++ b/src/channels/web/static/app.js
@@ -181,6 +181,7 @@ function confirmRestart() {
     body: {
       content: '/restart',
       thread_id: currentThreadId,
+      timezone: Intl.DateTimeFormat().resolvedOptions().timeZone,
     },
   })
     .then((response) => {
@@ -454,7 +455,7 @@ function sendMessage() {
 
   apiFetch('/api/chat/send', {
     method: 'POST',
-    body: { content, thread_id: currentThreadId || undefined },
+    body: { content, thread_id: currentThreadId || undefined, timezone: Intl.DateTimeFormat().resolvedOptions().timeZone },
   }).catch((err) => {
     addMessage('system', 'Failed to send: ' + err.message);
   });
diff --git a/src/channels/web/types.rs b/src/channels/web/types.rs
index 20844fc5..7d65965d 100644
--- a/src/channels/web/types.rs
+++ b/src/channels/web/types.rs
@@ -9,6 +9,7 @@ use uuid::Uuid;
 pub struct SendMessageRequest {
     pub content: String,
     pub thread_id: Option<String>,
+    pub timezone: Option<String>,
 }
 
 #[derive(Debug, Serialize)]
@@ -613,6 +614,7 @@ pub enum WsClientMessage {
     Message {
         content: String,
         thread_id: Option<String>,
+        timezone: Option<String>,
     },
     /// Approve or deny a pending tool execution.
     #[serde(rename = "approval")]
@@ -798,7 +800,9 @@ mod tests {
         let json = r#"{"type":"message","content":"hello","thread_id":"t1"}"#;
         let msg: WsClientMessage = serde_json::from_str(json).unwrap();
         match msg {
-            WsClientMessage::Message { content, thread_id } => {
+            WsClientMessage::Message {
+                content, thread_id, ..
+            } => {
                 assert_eq!(content, "hello");
                 assert_eq!(thread_id.as_deref(), Some("t1"));
             }
@@ -811,7 +815,9 @@ mod tests {
         let json = r#"{"type":"message","content":"hi"}"#;
         let msg: WsClientMessage = serde_json::from_str(json).unwrap();
         match msg {
-            WsClientMessage::Message { content, thread_id } => {
+            WsClientMessage::Message {
+                content, thread_id, ..
+            } => {
                 assert_eq!(content, "hi");
                 assert!(thread_id.is_none());
             }
diff --git a/src/channels/web/ws.rs b/src/channels/web/ws.rs
index 8a0caa54..e9e3c8e6 100644
--- a/src/channels/web/ws.rs
+++ b/src/channels/web/ws.rs
@@ -156,8 +156,15 @@ async fn handle_client_message(
     direct_tx: &mpsc::Sender<WsServerMessage>,
 ) {
     match msg {
-        WsClientMessage::Message { content, thread_id } => {
+        WsClientMessage::Message {
+            content,
+            thread_id,
+            timezone,
+        } => {
             let mut incoming = IncomingMessage::new("gateway", user_id, &content);
+            if let Some(ref tz) = timezone {
+                incoming = incoming.with_timezone(tz);
+            }
             if let Some(ref tid) = thread_id {
                 incoming = incoming.with_thread(tid);
             }
@@ -349,6 +356,7 @@ mod tests {
             WsClientMessage::Message {
                 content: "hello agent".to_string(),
                 thread_id: Some("t1".to_string()),
+                timezone: None,
             },
             &state,
             "user1",
@@ -373,6 +381,7 @@ mod tests {
             WsClientMessage::Message {
                 content: "hello".to_string(),
                 thread_id: None,
+                timezone: None,
             },
             &state,
             "user1",
diff --git a/src/config/agent.rs b/src/config/agent.rs
index b94e5d4b..096c141f 100644
--- a/src/config/agent.rs
+++ b/src/config/agent.rs
@@ -27,6 +27,8 @@ pub struct AgentConfig {
     pub max_tool_iterations: usize,
     /// When true, skip tool approval checks entirely. For benchmarks/CI.
     pub auto_approve_tools: bool,
+    /// Default timezone for new sessions (IANA name, e.g. "America/New_York").
+    pub default_timezone: String,
 }
 
 impl AgentConfig {
@@ -47,6 +49,7 @@ impl AgentConfig {
             max_actions_per_hour: None,
             max_tool_iterations: 10,
             auto_approve_tools: true,
+            default_timezone: "UTC".to_string(),
         }
     }
 
@@ -89,6 +92,40 @@ impl AgentConfig {
                 "AGENT_AUTO_APPROVE_TOOLS",
                 settings.agent.auto_approve_tools,
             )?,
+            default_timezone: {
+                let tz: String = parse_optional_env(
+                    "DEFAULT_TIMEZONE",
+                    settings.agent.default_timezone.clone(),
+                )?;
+                if crate::timezone::parse_timezone(&tz).is_none() {
+                    return Err(ConfigError::InvalidValue {
+                        key: "DEFAULT_TIMEZONE".into(),
+                        message: format!("invalid IANA timezone: '{tz}'"),
+                    });
+                }
+                tz
+            },
         })
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_default_timezone_rejects_invalid() {
+        let mut settings = Settings::default();
+        settings.agent.default_timezone = "Fake/Zone".to_string();
+
+        let result = AgentConfig::resolve(&settings);
+        assert!(result.is_err(), "invalid IANA timezone should be rejected");
+    }
+
+    #[test]
+    fn test_default_timezone_accepts_valid() {
+        let settings = Settings::default(); // default is "UTC"
+        let config = AgentConfig::resolve(&settings).expect("resolve");
+        assert_eq!(config.default_timezone, "UTC");
+    }
+}
diff --git a/src/config/heartbeat.rs b/src/config/heartbeat.rs
index f2f98071..3de1da66 100644
--- a/src/config/heartbeat.rs
+++ b/src/config/heartbeat.rs
@@ -1,4 +1,4 @@
-use crate::config::helpers::{optional_env, parse_bool_env, parse_optional_env};
+use crate::config::helpers::{optional_env, parse_bool_env, parse_option_env, parse_optional_env};
 use crate::error::ConfigError;
 use crate::settings::Settings;
 
@@ -13,6 +13,12 @@ pub struct HeartbeatConfig {
     pub notify_channel: Option<String>,
     /// User ID to notify on heartbeat findings.
     pub notify_user: Option<String>,
+    /// Hour (0-23) when quiet hours start.
+    pub quiet_hours_start: Option<u32>,
+    /// Hour (0-23) when quiet hours end.
+    pub quiet_hours_end: Option<u32>,
+    /// Timezone for quiet hours evaluation (IANA name).
+    pub timezone: Option<String>,
 }
 
 impl Default for HeartbeatConfig {
@@ -22,6 +28,9 @@ impl Default for HeartbeatConfig {
             interval_secs: 1800, // 30 minutes
             notify_channel: None,
             notify_user: None,
+            quiet_hours_start: None,
+            quiet_hours_end: None,
+            timezone: None,
         }
     }
 }
@@ -38,6 +47,98 @@ impl HeartbeatConfig {
                 .or_else(|| settings.heartbeat.notify_channel.clone()),
             notify_user: optional_env("HEARTBEAT_NOTIFY_USER")?
                 .or_else(|| settings.heartbeat.notify_user.clone()),
+            quiet_hours_start: parse_option_env::<u32>("HEARTBEAT_QUIET_START")?
+                .or(settings.heartbeat.quiet_hours_start)
+                .map(|h| {
+                    if h > 23 {
+                        return Err(ConfigError::InvalidValue {
+                            key: "HEARTBEAT_QUIET_START".into(),
+                            message: "must be 0-23".into(),
+                        });
+                    }
+                    Ok(h)
+                })
+                .transpose()?,
+            quiet_hours_end: parse_option_env::<u32>("HEARTBEAT_QUIET_END")?
+                .or(settings.heartbeat.quiet_hours_end)
+                .map(|h| {
+                    if h > 23 {
+                        return Err(ConfigError::InvalidValue {
+                            key: "HEARTBEAT_QUIET_END".into(),
+                            message: "must be 0-23".into(),
+                        });
+                    }
+                    Ok(h)
+                })
+                .transpose()?,
+            timezone: {
+                let tz = optional_env("HEARTBEAT_TIMEZONE")?
+                    .or_else(|| settings.heartbeat.timezone.clone());
+                if let Some(ref tz_str) = tz
+                    && crate::timezone::parse_timezone(tz_str).is_none()
+                {
+                    return Err(ConfigError::InvalidValue {
+                        key: "HEARTBEAT_TIMEZONE".into(),
+                        message: format!("invalid IANA timezone: '{tz_str}'"),
+                    });
+                }
+                tz
+            },
         })
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_quiet_hours_settings_fallback() {
+        // When env vars are not set, settings values should be used
+        let mut settings = Settings::default();
+        settings.heartbeat.quiet_hours_start = Some(22);
+        settings.heartbeat.quiet_hours_end = Some(6);
+
+        let config = HeartbeatConfig::resolve(&settings).expect("resolve");
+        assert_eq!(config.quiet_hours_start, Some(22));
+        assert_eq!(config.quiet_hours_end, Some(6));
+    }
+
+    #[test]
+    fn test_quiet_hours_rejects_invalid_hour() {
+        let mut settings = Settings::default();
+        settings.heartbeat.quiet_hours_start = Some(24);
+
+        let result = HeartbeatConfig::resolve(&settings);
+        assert!(result.is_err());
+    }
+
+    #[test]
+    fn test_quiet_hours_accepts_boundary_values() {
+        let mut settings = Settings::default();
+        settings.heartbeat.quiet_hours_start = Some(0);
+        settings.heartbeat.quiet_hours_end = Some(23);
+
+        let config = HeartbeatConfig::resolve(&settings).expect("resolve");
+        assert_eq!(config.quiet_hours_start, Some(0));
+        assert_eq!(config.quiet_hours_end, Some(23));
+    }
+
+    #[test]
+    fn test_heartbeat_timezone_rejects_invalid() {
+        let mut settings = Settings::default();
+        settings.heartbeat.timezone = Some("Fake/Zone".to_string());
+
+        let result = HeartbeatConfig::resolve(&settings);
+        assert!(result.is_err(), "invalid IANA timezone should be rejected");
+    }
+
+    #[test]
+    fn test_heartbeat_timezone_accepts_valid() {
+        let mut settings = Settings::default();
+        settings.heartbeat.timezone = Some("America/New_York".to_string());
+
+        let config = HeartbeatConfig::resolve(&settings).expect("resolve");
+        assert_eq!(config.timezone.as_deref(), Some("America/New_York"));
+    }
+}
diff --git a/src/context/state.rs b/src/context/state.rs
index 5b9c200b..a55cb8d1 100644
--- a/src/context/state.rs
+++ b/src/context/state.rs
@@ -164,6 +164,8 @@ pub struct JobContext {
     /// previous results by ID via `$tool_call_id` parameter syntax.
     #[serde(skip)]
     pub tool_output_stash: Arc<tokio::sync::RwLock<HashMap<String, String>>>,
+    /// User's preferred timezone (IANA name, e.g. "America/New_York"). Defaults to "UTC".
+    pub user_timezone: String,
 }
 
 impl JobContext {
@@ -203,9 +205,16 @@ impl JobContext {
             http_interceptor: None,
             metadata: serde_json::Value::Null,
             tool_output_stash: Arc::new(tokio::sync::RwLock::new(HashMap::new())),
+            user_timezone: "UTC".to_string(),
         }
     }
 
+    /// Set the user timezone on this context.
+    pub fn with_timezone(mut self, tz: impl Into<String>) -> Self {
+        self.user_timezone = tz.into();
+        self
+    }
+
     /// Transition to a new state.
     pub fn transition_to(
         &mut self,
diff --git a/src/db/libsql/jobs.rs b/src/db/libsql/jobs.rs
index 37506b51..d5172360 100644
--- a/src/db/libsql/jobs.rs
+++ b/src/db/libsql/jobs.rs
@@ -121,6 +121,9 @@ impl JobStore for LibSqlBackend {
                     tool_output_stash: std::sync::Arc::new(tokio::sync::RwLock::new(
                         std::collections::HashMap::new(),
                     )),
+                    // TODO(#661): persist user_timezone in agent_jobs table so
+                    // background/routine jobs retain the session's timezone context.
+                    user_timezone: "UTC".to_string(),
                 }))
             }
             None => Ok(None),
diff --git a/src/history/store.rs b/src/history/store.rs
index 2a46aaea..f0b0b144 100644
--- a/src/history/store.rs
+++ b/src/history/store.rs
@@ -241,6 +241,9 @@ impl Store {
                     tool_output_stash: std::sync::Arc::new(tokio::sync::RwLock::new(
                         std::collections::HashMap::new(),
                     )),
+                    // TODO(#661): persist user_timezone in agent_jobs table so
+                    // background/routine jobs retain the session's timezone context.
+                    user_timezone: "UTC".to_string(),
                 }))
             }
             None => Ok(None),
diff --git a/src/lib.rs b/src/lib.rs
index fff5c5fa..128d3edc 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -66,6 +66,7 @@ pub mod service;
 pub mod settings;
 pub mod setup;
 pub mod skills;
+pub mod timezone;
 pub mod tools;
 pub mod tracing_fmt;
 pub mod transcription;
diff --git a/src/settings.rs b/src/settings.rs
index 8e62feaf..92fe207d 100644
--- a/src/settings.rs
+++ b/src/settings.rs
@@ -291,6 +291,18 @@ pub struct HeartbeatSettings {
     /// User ID to notify on heartbeat findings.
     #[serde(default)]
     pub notify_user: Option<String>,
+
+    /// Hour (0-23) when quiet hours start (heartbeat skipped).
+    #[serde(default)]
+    pub quiet_hours_start: Option<u32>,
+
+    /// Hour (0-23) when quiet hours end (heartbeat resumes).
+    #[serde(default)]
+    pub quiet_hours_end: Option<u32>,
+
+    /// Timezone for quiet hours evaluation (IANA name, e.g. "America/New_York").
+    #[serde(default)]
+    pub timezone: Option<String>,
 }
 
 fn default_heartbeat_interval() -> u64 {
@@ -304,6 +316,9 @@ impl Default for HeartbeatSettings {
             interval_secs: default_heartbeat_interval(),
             notify_channel: None,
             notify_user: None,
+            quiet_hours_start: None,
+            quiet_hours_end: None,
+            timezone: None,
         }
     }
 }
@@ -351,6 +366,10 @@ pub struct AgentSettings {
     /// When true, skip tool approval checks entirely. For benchmarks/CI.
     #[serde(default)]
     pub auto_approve_tools: bool,
+
+    /// Default timezone for new sessions (IANA name, e.g. "America/New_York").
+    #[serde(default = "default_timezone")]
+    pub default_timezone: String,
 }
 
 fn default_agent_name() -> String {
@@ -385,6 +404,10 @@ fn default_max_tool_iterations() -> usize {
     50
 }
 
+fn default_timezone() -> String {
+    "UTC".to_string()
+}
+
 fn default_true() -> bool {
     true
 }
@@ -402,6 +425,7 @@ impl Default for AgentSettings {
             session_idle_timeout_secs: default_session_idle_timeout(),
             max_tool_iterations: default_max_tool_iterations(),
             auto_approve_tools: false,
+            default_timezone: default_timezone(),
         }
     }
 }
diff --git a/src/testing.rs b/src/testing.rs
index 8660f82f..8f57cffc 100644
--- a/src/testing.rs
+++ b/src/testing.rs
@@ -1009,6 +1009,7 @@ mod tests {
             enabled: true,
             trigger: Trigger::Cron {
                 schedule: "0 * * * *".to_string(),
+                timezone: None,
             },
             action: RoutineAction::Lightweight {
                 prompt: "Check status".to_string(),
diff --git a/src/timezone.rs b/src/timezone.rs
new file mode 100644
index 00000000..e0f93b76
--- /dev/null
+++ b/src/timezone.rs
@@ -0,0 +1,110 @@
+//! Timezone resolution and utilities.
+
+use chrono::{DateTime, NaiveDate, Utc};
+use chrono_tz::Tz;
+
+/// Resolve the effective timezone from a priority chain.
+///
+/// Priority: client_tz > user_setting > config_default > UTC
+pub fn resolve_timezone(
+    client_tz: Option<&str>,
+    user_setting: Option<&str>,
+    config_default: &str,
+) -> Tz {
+    // Try each in priority order, skipping invalid values
+    for candidate in [client_tz, user_setting, Some(config_default)] {
+        if let Some(tz) = candidate.and_then(parse_timezone) {
+            return tz;
+        }
+    }
+    Tz::UTC
+}
+
+/// Parse a timezone string (IANA name) into a `Tz`.
+pub fn parse_timezone(s: &str) -> Option<Tz> {
+    s.parse::<Tz>().ok()
+}
+
+/// Get today's date in the given timezone.
+pub fn today_in_tz(tz: Tz) -> NaiveDate {
+    Utc::now().with_timezone(&tz).date_naive()
+}
+
+/// Get the current time in the given timezone.
+pub fn now_in_tz(tz: Tz) -> DateTime<Tz> {
+    Utc::now().with_timezone(&tz)
+}
+
+/// Detect the system's timezone, falling back to UTC.
+pub fn detect_system_timezone() -> Tz {
+    iana_time_zone::get_timezone()
+        .ok()
+        .and_then(|s| parse_timezone(&s))
+        .unwrap_or(Tz::UTC)
+}
+
+#[cfg(test)]
+mod tests {
+    use chrono::Datelike;
+
+    use super::*;
+
+    #[test]
+    fn test_resolve_client_wins() {
+        let tz = resolve_timezone(Some("America/New_York"), Some("Europe/London"), "UTC");
+        assert_eq!(tz, chrono_tz::America::New_York);
+    }
+
+    #[test]
+    fn test_resolve_user_setting_fallback() {
+        let tz = resolve_timezone(None, Some("Europe/London"), "UTC");
+        assert_eq!(tz, chrono_tz::Europe::London);
+    }
+
+    #[test]
+    fn test_resolve_config_fallback() {
+        let tz = resolve_timezone(None, None, "Asia/Tokyo");
+        assert_eq!(tz, chrono_tz::Asia::Tokyo);
+    }
+
+    #[test]
+    fn test_resolve_all_none_utc() {
+        let tz = resolve_timezone(None, None, "UTC");
+        assert_eq!(tz, Tz::UTC);
+    }
+
+    #[test]
+    fn test_resolve_invalid_client_skipped() {
+        let tz = resolve_timezone(Some("Fake/Zone"), Some("Europe/London"), "UTC");
+        assert_eq!(tz, chrono_tz::Europe::London);
+    }
+
+    #[test]
+    fn test_parse_valid() {
+        assert_eq!(
+            parse_timezone("America/Chicago"),
+            Some(chrono_tz::America::Chicago)
+        );
+    }
+
+    #[test]
+    fn test_parse_invalid() {
+        assert_eq!(parse_timezone("Fake/Zone"), None);
+    }
+
+    #[test]
+    fn test_detect_system_tz() {
+        // Should always return a valid Tz (at minimum UTC)
+        let tz = detect_system_timezone();
+        let _ = now_in_tz(tz); // Should not panic
+    }
+
+    #[test]
+    fn test_today_in_tz_returns_valid_date() {
+        let date = today_in_tz(Tz::UTC);
+        // Verify it returns a valid date (year, month, day are all positive)
+        assert!(date.year() > 0);
+        assert!((1..=12).contains(&date.month()));
+        assert!((1..=31).contains(&date.day()));
+    }
+}
diff --git a/src/tools/builtin/memory.rs b/src/tools/builtin/memory.rs
index dbb6b20b..71fe8a3b 100644
--- a/src/tools/builtin/memory.rs
+++ b/src/tools/builtin/memory.rs
@@ -172,7 +172,7 @@ impl Tool for MemoryWriteTool {
     async fn execute(
         &self,
         params: serde_json::Value,
-        _ctx: &JobContext,
+        ctx: &JobContext,
     ) -> Result<ToolOutput, ToolError> {
         let start = std::time::Instant::now();
 
@@ -239,11 +239,12 @@ impl Tool for MemoryWriteTool {
                 paths::MEMORY.to_string()
             }
             "daily_log" => {
+                let tz = crate::timezone::parse_timezone(&ctx.user_timezone)
+                    .unwrap_or(chrono_tz::Tz::UTC);
                 self.workspace
-                    .append_daily_log(content)
+                    .append_daily_log_tz(content, tz)
                     .await
-                    .map_err(|e| ToolError::ExecutionFailed(format!("Write failed: {}", e)))?;
-                format!("daily/{}.md", chrono::Utc::now().format("%Y-%m-%d"))
+                    .map_err(|e| ToolError::ExecutionFailed(format!("Write failed: {}", e)))?
             }
             "heartbeat" => {
                 if append {
diff --git a/src/tools/builtin/routine.rs b/src/tools/builtin/routine.rs
index 2fddec29..090d1ff9 100644
--- a/src/tools/builtin/routine.rs
+++ b/src/tools/builtin/routine.rs
@@ -107,6 +107,10 @@ impl Tool for RoutineCreateTool {
                 "notify_user": {
                     "type": "string",
                     "description": "User/target to notify (e.g. username, chat ID). Defaults to 'default'."
+                },
+                "timezone": {
+                    "type": "string",
+                    "description": "IANA timezone for cron schedule evaluation (e.g. 'America/New_York'). Defaults to UTC."
                 }
             },
             "required": ["name", "trigger_type", "prompt"]
@@ -143,12 +147,26 @@ impl Tool for RoutineCreateTool {
                                 "cron trigger requires 'schedule'".to_string(),
                             )
                         })?;
+                let timezone = params
+                    .get("timezone")
+                    .and_then(|v| v.as_str())
+                    .map(|tz| {
+                        crate::timezone::parse_timezone(tz)
+                            .map(|_| tz.to_string())
+                            .ok_or_else(|| {
+                                ToolError::InvalidParameters(format!(
+                                    "invalid IANA timezone: '{tz}'"
+                                ))
+                            })
+                    })
+                    .transpose()?;
                 // Validate cron expression
-                next_cron_fire(schedule).map_err(|e| {
+                next_cron_fire(schedule, timezone.as_deref()).map_err(|e| {
                     ToolError::InvalidParameters(format!("invalid cron schedule: {e}"))
                 })?;
                 Trigger::Cron {
                     schedule: schedule.to_string(),
+                    timezone,
                 }
             }
             "event" => {
@@ -228,8 +246,12 @@ impl Tool for RoutineCreateTool {
             .unwrap_or(300);
 
         // Compute next fire time for cron
-        let next_fire = if let Trigger::Cron { ref schedule } = trigger {
-            next_cron_fire(schedule).unwrap_or(None)
+        let next_fire = if let Trigger::Cron {
+            ref schedule,
+            ref timezone,
+        } = trigger
+        {
+            next_cron_fire(schedule, timezone.as_deref()).unwrap_or(None)
         } else {
             None
         };
@@ -412,6 +434,10 @@ impl Tool for RoutineUpdateTool {
                     "type": "string",
                     "description": "New cron schedule (for cron triggers)"
                 },
+                "timezone": {
+                    "type": "string",
+                    "description": "IANA timezone for cron schedule (e.g. 'America/New_York'). Only valid for cron triggers."
+                },
                 "description": {
                     "type": "string",
                     "description": "New description"
@@ -453,15 +479,47 @@ impl Tool for RoutineUpdateTool {
             }
         }
 
-        if let Some(schedule) = params.get("schedule").and_then(|v| v.as_str()) {
-            // Validate
-            next_cron_fire(schedule)
-                .map_err(|e| ToolError::InvalidParameters(format!("invalid cron schedule: {e}")))?;
+        // Validate timezone param if provided
+        let new_timezone = params
+            .get("timezone")
+            .and_then(|v| v.as_str())
+            .map(|tz| {
+                crate::timezone::parse_timezone(tz)
+                    .map(|_| tz.to_string())
+                    .ok_or_else(|| {
+                        ToolError::InvalidParameters(format!("invalid IANA timezone: '{tz}'"))
+                    })
+            })
+            .transpose()?;
 
-            routine.trigger = Trigger::Cron {
-                schedule: schedule.to_string(),
+        let new_schedule = params.get("schedule").and_then(|v| v.as_str());
+
+        if new_schedule.is_some() || new_timezone.is_some() {
+            // Extract existing cron fields (cloned to avoid borrow conflict)
+            let existing_cron = match &routine.trigger {
+                Trigger::Cron { schedule, timezone } => Some((schedule.clone(), timezone.clone())),
+                _ => None,
             };
-            routine.next_fire_at = next_cron_fire(schedule).unwrap_or(None);
+
+            if let Some((old_schedule, old_tz)) = existing_cron {
+                let effective_schedule = new_schedule.unwrap_or(&old_schedule);
+                let effective_tz = new_timezone.or(old_tz);
+                // Validate
+                next_cron_fire(effective_schedule, effective_tz.as_deref()).map_err(|e| {
+                    ToolError::InvalidParameters(format!("invalid cron schedule: {e}"))
+                })?;
+
+                routine.trigger = Trigger::Cron {
+                    schedule: effective_schedule.to_string(),
+                    timezone: effective_tz.clone(),
+                };
+                routine.next_fire_at =
+                    next_cron_fire(effective_schedule, effective_tz.as_deref()).unwrap_or(None);
+            } else {
+                return Err(ToolError::InvalidParameters(
+                    "Cannot update schedule or timezone on a non-cron routine.".to_string(),
+                ));
+            }
         }
 
         self.store
diff --git a/src/tools/builtin/time.rs b/src/tools/builtin/time.rs
index 9388f8c7..d93c09e4 100644
--- a/src/tools/builtin/time.rs
+++ b/src/tools/builtin/time.rs
@@ -48,7 +48,7 @@ impl Tool for TimeTool {
     async fn execute(
         &self,
         params: serde_json::Value,
-        _ctx: &JobContext,
+        ctx: &JobContext,
     ) -> Result<ToolOutput, ToolError> {
         let start = std::time::Instant::now();
 
@@ -57,10 +57,15 @@ impl Tool for TimeTool {
         let result = match operation {
             "now" => {
                 let now = Utc::now();
+                let tz =
+                    crate::timezone::parse_timezone(&ctx.user_timezone).unwrap_or(chrono_tz::UTC);
+                let local = now.with_timezone(&tz);
                 serde_json::json!({
                     "iso": now.to_rfc3339(),
                     "unix": now.timestamp(),
-                    "unix_millis": now.timestamp_millis()
+                    "unix_millis": now.timestamp_millis(),
+                    "local_iso": local.to_rfc3339(),
+                    "timezone": tz.name()
                 })
             }
             "parse" => {
@@ -112,3 +117,42 @@ impl Tool for TimeTool {
         false // Internal tool, no external data
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[tokio::test]
+    async fn test_now_includes_local_time_when_timezone_set() {
+        let tool = TimeTool;
+        let mut ctx = JobContext::with_user("test", "chat", "test");
+        ctx.user_timezone = "America/New_York".to_string();
+
+        let output = tool
+            .execute(serde_json::json!({"operation": "now"}), &ctx)
+            .await
+            .expect("execute");
+        assert!(
+            output.result.get("local_iso").is_some(),
+            "should have local_iso"
+        );
+        assert_eq!(
+            output.result["timezone"].as_str(),
+            Some("America/New_York"),
+            "should report timezone"
+        );
+    }
+
+    #[tokio::test]
+    async fn test_now_includes_utc_timezone_by_default() {
+        let tool = TimeTool;
+        let ctx = JobContext::with_user("test", "chat", "test");
+        // Default user_timezone is "UTC" which is a valid IANA timezone
+        let output = tool
+            .execute(serde_json::json!({"operation": "now"}), &ctx)
+            .await
+            .expect("execute");
+        assert!(output.result.get("iso").is_some(), "should have iso");
+        assert_eq!(output.result["timezone"].as_str(), Some("UTC"));
+    }
+}
diff --git a/src/workspace/mod.rs b/src/workspace/mod.rs
index 6196b3f1..16c7bc0e 100644
--- a/src/workspace/mod.rs
+++ b/src/workspace/mod.rs
@@ -565,11 +565,26 @@ impl Workspace {
     ///
     /// Daily logs are raw, append-only notes for the current day.
     pub async fn append_daily_log(&self, entry: &str) -> Result<(), WorkspaceError> {
-        let today = Utc::now().date_naive();
+        self.append_daily_log_tz(entry, chrono_tz::Tz::UTC)
+            .await
+            .map(|_| ())
+    }
+
+    /// Append an entry to today's daily log using the given timezone.
+    ///
+    /// Returns the path that was written to (e.g. `daily/2024-01-15.md`).
+    pub async fn append_daily_log_tz(
+        &self,
+        entry: &str,
+        tz: chrono_tz::Tz,
+    ) -> Result<String, WorkspaceError> {
+        let now = crate::timezone::now_in_tz(tz);
+        let today = now.date_naive();
         let path = format!("daily/{}.md", today.format("%Y-%m-%d"));
-        let timestamp = Utc::now().format("%H:%M:%S");
+        let timestamp = now.format("%H:%M:%S");
         let timestamped_entry = format!("[{}] {}", timestamp, entry);
-        self.append(&path, &timestamped_entry).await
+        self.append(&path, &timestamped_entry).await?;
+        Ok(path)
     }
 
     // ==================== System Prompt ====================
@@ -584,6 +599,18 @@ impl Workspace {
         self.system_prompt_for_context(false).await
     }
 
+    /// Build the system prompt with timezone-aware daily log dates.
+    ///
+    /// Uses the given timezone to determine "today" and "yesterday" for daily log injection.
+    pub async fn system_prompt_for_context_tz(
+        &self,
+        is_group_chat: bool,
+        tz: chrono_tz::Tz,
+    ) -> Result<String, WorkspaceError> {
+        self.system_prompt_for_context_inner(is_group_chat, Some(tz))
+            .await
+    }
+
     /// Build the system prompt, optionally excluding personal memory.
     ///
     /// When `is_group_chat` is true, MEMORY.md is excluded to prevent
@@ -591,6 +618,16 @@ impl Workspace {
     pub async fn system_prompt_for_context(
         &self,
         is_group_chat: bool,
+    ) -> Result<String, WorkspaceError> {
+        self.system_prompt_for_context_inner(is_group_chat, None)
+            .await
+    }
+
+    /// Inner implementation for system prompt building.
+    async fn system_prompt_for_context_inner(
+        &self,
+        is_group_chat: bool,
+        tz: Option<chrono_tz::Tz>,
     ) -> Result<String, WorkspaceError> {
         let mut parts = Vec::new();
 
@@ -645,7 +682,10 @@ impl Workspace {
         }
 
         // Add today's memory context (last 2 days of daily logs)
-        let today = Utc::now().date_naive();
+        let today = match tz {
+            Some(t) => crate::timezone::today_in_tz(t),
+            None => Utc::now().date_naive(),
+        };
         let yesterday = today.pred_opt().unwrap_or(today);
 
         for date in [today, yesterday] {
diff --git a/tests/e2e_routine_heartbeat.rs b/tests/e2e_routine_heartbeat.rs
index 1e65fb3d..2e124816 100644
--- a/tests/e2e_routine_heartbeat.rs
+++ b/tests/e2e_routine_heartbeat.rs
@@ -118,6 +118,7 @@ mod tests {
             "cron-test",
             Trigger::Cron {
                 schedule: "* * * * *".to_string(),
+                timezone: None,
             },
             "Check system status.",
         );
@@ -203,6 +204,7 @@ mod tests {
             thread_id: None,
             received_at: Utc::now(),
             metadata: serde_json::json!({}),
+            timezone: None,
             attachments: Vec::new(),
         };
         let fired = engine.check_event_triggers(&matching_msg).await;
@@ -224,6 +226,7 @@ mod tests {
             thread_id: None,
             received_at: Utc::now(),
             metadata: serde_json::json!({}),
+            timezone: None,
             attachments: Vec::new(),
         };
         let fired_neg = engine.check_event_triggers(&non_matching_msg).await;
@@ -288,6 +291,7 @@ mod tests {
             thread_id: None,
             received_at: Utc::now(),
             metadata: serde_json::json!({}),
+            timezone: None,
             attachments: Vec::new(),
         };
         let fired1 = engine.check_event_triggers(&msg).await;