chore: update exec crate to use std::time instead of chrono (#952)

When I originally wrote `elapsed.rs`, I realized we were using both
`std::time` and `chrono` with no real benefit of having both. We should
try to keep the `exec` subcommand trim (as it also buildable as a
standalone executable), so this helps tighten things up.

codex-rs/Cargo.lock

@@ -503,7 +503,6 @@ dependencies = [
 name = "codex-common"
 version = "0.0.0"
 dependencies = [
- "chrono",
  "clap",
  "codex-core",
 ]

codex-rs/common/Cargo.toml

@@ -7,11 +7,10 @@ edition = "2024"
 workspace = true
 
 [dependencies]
-chrono = { version = "0.4.40", optional = true }
 clap = { version = "4", features = ["derive", "wrap_help"], optional = true }
 codex-core = { path = "../core" }
 
 [features]
 # Separate feature so that `clap` is not a mandatory dependency.
 cli = ["clap"]
-elapsed = ["chrono"]
+elapsed = []

codex-rs/common/src/elapsed.rs

@@ -1,18 +1,19 @@
-use chrono::Utc;
+use std::time::Duration;
+use std::time::Instant;
 
 /// Returns a string representing the elapsed time since `start_time` like
 /// "1m15s" or "1.50s".
-pub fn format_elapsed(start_time: chrono::DateTime<Utc>) -> String {
-    let elapsed = Utc::now().signed_duration_since(start_time);
-    format_time_delta(elapsed)
+pub fn format_elapsed(start_time: Instant) -> String {
+    format_duration(start_time.elapsed())
 }
 
-fn format_time_delta(elapsed: chrono::TimeDelta) -> String {
-    let millis = elapsed.num_milliseconds();
-    format_elapsed_millis(millis)
-}
-
-pub fn format_duration(duration: std::time::Duration) -> String {
+/// Convert a [`std::time::Duration`] into a human-readable, compact string.
+///
+/// Formatting rules:
+/// * < 1 s  ->  "{milli}ms"
+/// * < 60 s ->  "{sec:.2}s" (two decimal places)
+/// * >= 60 s ->  "{min}m{sec:02}s"
+pub fn format_duration(duration: Duration) -> String {
     let millis = duration.as_millis() as i64;
     format_elapsed_millis(millis)
 }
@@ -32,41 +33,40 @@ fn format_elapsed_millis(millis: i64) -> String {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use chrono::Duration;
 
     #[test]
-    fn test_format_time_delta_subsecond() {
+    fn test_format_duration_subsecond() {
         // Durations < 1s should be rendered in milliseconds with no decimals.
-        let dur = Duration::milliseconds(250);
-        assert_eq!(format_time_delta(dur), "250ms");
+        let dur = Duration::from_millis(250);
+        assert_eq!(format_duration(dur), "250ms");
 
         // Exactly zero should still work.
-        let dur_zero = Duration::milliseconds(0);
-        assert_eq!(format_time_delta(dur_zero), "0ms");
+        let dur_zero = Duration::from_millis(0);
+        assert_eq!(format_duration(dur_zero), "0ms");
     }
 
     #[test]
-    fn test_format_time_delta_seconds() {
+    fn test_format_duration_seconds() {
         // Durations between 1s (inclusive) and 60s (exclusive) should be
         // printed with 2-decimal-place seconds.
-        let dur = Duration::milliseconds(1_500); // 1.5s
-        assert_eq!(format_time_delta(dur), "1.50s");
+        let dur = Duration::from_millis(1_500); // 1.5s
+        assert_eq!(format_duration(dur), "1.50s");
 
         // 59.999s rounds to 60.00s
-        let dur2 = Duration::milliseconds(59_999);
-        assert_eq!(format_time_delta(dur2), "60.00s");
+        let dur2 = Duration::from_millis(59_999);
+        assert_eq!(format_duration(dur2), "60.00s");
     }
 
     #[test]
-    fn test_format_time_delta_minutes() {
+    fn test_format_duration_minutes() {
         // Durations ≥ 1 minute should be printed mmss.
-        let dur = Duration::milliseconds(75_000); // 1m15s
-        assert_eq!(format_time_delta(dur), "1m15s");
+        let dur = Duration::from_millis(75_000); // 1m15s
+        assert_eq!(format_duration(dur), "1m15s");
 
-        let dur_exact = Duration::milliseconds(60_000); // 1m0s
-        assert_eq!(format_time_delta(dur_exact), "1m00s");
+        let dur_exact = Duration::from_millis(60_000); // 1m0s
+        assert_eq!(format_duration(dur_exact), "1m00s");
 
-        let dur_long = Duration::milliseconds(3_601_000);
-        assert_eq!(format_time_delta(dur_long), "60m01s");
+        let dur_long = Duration::from_millis(3_601_000);
+        assert_eq!(format_duration(dur_long), "60m01s");
     }
 }

codex-rs/exec/src/event_processor.rs

@@ -17,6 +17,7 @@ use owo_colors::OwoColorize;
 use owo_colors::Style;
 use shlex::try_join;
 use std::collections::HashMap;
+use std::time::Instant;
 
 /// This should be configurable. When used in CI, users may not want to impose
 /// a limit so they can see the full transcript.
@@ -76,7 +77,7 @@ impl EventProcessor {
 
 struct ExecCommandBegin {
     command: Vec<String>,
-    start_time: chrono::DateTime<Utc>,
+    start_time: Instant,
 }
 
 /// Metadata captured when an `McpToolCallBegin` event is received.
@@ -84,11 +85,11 @@ struct McpToolCallBegin {
     /// Formatted invocation string, e.g. `server.tool({"city":"sf"})`.
     invocation: String,
     /// Timestamp when the call started so we can compute duration later.
-    start_time: chrono::DateTime<Utc>,
+    start_time: Instant,
 }
 
 struct PatchApplyBegin {
-    start_time: chrono::DateTime<Utc>,
+    start_time: Instant,
     auto_approved: bool,
 }
 
@@ -133,7 +134,7 @@ impl EventProcessor {
                     call_id.clone(),
                     ExecCommandBegin {
                         command: command.clone(),
-                        start_time: Utc::now(),
+                        start_time: Instant::now(),
                     },
                 );
                 ts_println!(
@@ -208,7 +209,7 @@ impl EventProcessor {
                     call_id.clone(),
                     McpToolCallBegin {
                         invocation: invocation.clone(),
-                        start_time: Utc::now(),
+                        start_time: Instant::now(),
                     },
                 );
 
@@ -263,7 +264,7 @@ impl EventProcessor {
                 self.call_id_to_patch.insert(
                     call_id.clone(),
                     PatchApplyBegin {
-                        start_time: Utc::now(),
+                        start_time: Instant::now(),
                         auto_approved,
                     },
                 );