[core] debounce current-time reminders by elapsed time (#29659)

## Summary
- rename `reminder_interval_model_requests` to
`reminder_interval_seconds`
- read the configured time provider before every model request and
inject a reminder only after the configured number of seconds has
elapsed
- preserve immediate first delivery and forced delivery after compaction
changes the context window

## Tests
- `just test -p codex-core current_time_reminder`

codex-rs/core/src/config/config_tests.rs

@@ -620,11 +620,11 @@ current_time_reminder = true
             r#"
 [features.current_time_reminder]
 enabled = true
-reminder_interval_model_requests = 4
+reminder_interval_seconds = 4
 clock_source = "external"
 "#,
             CurrentTimeReminderConfig {
-                reminder_interval_model_requests: 4,
+                reminder_interval_seconds: 4,
                 clock_source: CurrentTimeSource::External,
             },
         ),
@@ -642,7 +642,7 @@ async fn load_config_rejects_zero_current_time_reminder_interval() -> std::io::R
         r#"
 [features.current_time_reminder]
 enabled = true
-reminder_interval_model_requests = 0
+reminder_interval_seconds = 0
 "#,
     )
     .await
@@ -651,7 +651,7 @@ reminder_interval_model_requests = 0
     assert_eq!(error.kind(), std::io::ErrorKind::InvalidInput);
     assert_eq!(
         error.to_string(),
-        "features.current_time_reminder.reminder_interval_model_requests must be positive"
+        "features.current_time_reminder.reminder_interval_seconds must be positive"
     );
     Ok(())
 }

codex-rs/core/src/config/mod.rs

@@ -1115,14 +1115,14 @@ pub struct RolloutBudgetConfig {
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize)]
 pub struct CurrentTimeReminderConfig {
-    pub reminder_interval_model_requests: u64,
+    pub reminder_interval_seconds: u64,
     pub clock_source: CurrentTimeSource,
 }
 
 impl Default for CurrentTimeReminderConfig {
     fn default() -> Self {
         Self {
-            reminder_interval_model_requests: 1,
+            reminder_interval_seconds: 1,
             clock_source: CurrentTimeSource::System,
         }
     }
@@ -2657,18 +2657,18 @@ fn resolve_current_time_reminder_config(
 
     let base = current_time_reminder_toml_config(config_toml.features.as_ref());
     let default = CurrentTimeReminderConfig::default();
-    let reminder_interval_model_requests = base
-        .and_then(|config| config.reminder_interval_model_requests)
-        .unwrap_or(default.reminder_interval_model_requests);
-    if reminder_interval_model_requests == 0 {
+    let reminder_interval_seconds = base
+        .and_then(|config| config.reminder_interval_seconds)
+        .unwrap_or(default.reminder_interval_seconds);
+    if reminder_interval_seconds == 0 {
         return Err(std::io::Error::new(
             std::io::ErrorKind::InvalidInput,
-            "features.current_time_reminder.reminder_interval_model_requests must be positive",
+            "features.current_time_reminder.reminder_interval_seconds must be positive",
         ));
     }
 
     Ok(Some(CurrentTimeReminderConfig {
-        reminder_interval_model_requests,
+        reminder_interval_seconds,
         clock_source: base
             .and_then(|config| config.clock_source)
             .unwrap_or(default.clock_source),