[codex] current time reminder interval to be set to 0 (#30029)

A zero interval lets callers request a reminder at every
otherwise-eligible inference boundary.

## Validation
- just test -p codex-core load_config_resolves_current_time_reminder

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

@@ -625,12 +625,12 @@ current_time_reminder = true
             r#"
 [features.current_time_reminder]
 enabled = true
-reminder_interval_seconds = 4
+reminder_interval_seconds = 0
 clock_source = "external"
 sleep_tool = true
 "#,
             CurrentTimeReminderConfig {
-                reminder_interval_seconds: 4,
+                reminder_interval_seconds: 0,
                 clock_source: CurrentTimeSource::External,
                 sleep_tool: true,
             },
@@ -643,26 +643,6 @@ sleep_tool = true
     Ok(())
 }
 
-#[tokio::test]
-async fn load_config_rejects_zero_current_time_reminder_interval() -> std::io::Result<()> {
-    let error = load_current_time_reminder_config(
-        r#"
-[features.current_time_reminder]
-enabled = true
-reminder_interval_seconds = 0
-"#,
-    )
-    .await
-    .expect_err("zero reminder interval should be rejected");
-
-    assert_eq!(error.kind(), std::io::ErrorKind::InvalidInput);
-    assert_eq!(
-        error.to_string(),
-        "features.current_time_reminder.reminder_interval_seconds must be positive"
-    );
-    Ok(())
-}
-
 async fn load_current_time_reminder_config(config_toml: &str) -> std::io::Result<Config> {
     let codex_home = tempdir()?;
     let config_toml = toml::from_str(config_toml).expect("TOML should deserialize");

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

@@ -2685,12 +2685,6 @@ fn resolve_current_time_reminder_config(
     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_seconds must be positive",
-        ));
-    }
 
     Ok(Some(CurrentTimeReminderConfig {
         reminder_interval_seconds,