Add a stable TUI/app-server version comparison helper (#43619)

## What changed

Add `is_official_server_older` to check whether a stable TUI version is newer than the app-server version. Require both versions to contain exactly three numeric components without leading zeros, and return `false` for source builds (`0.0.0`), prereleases, and malformed versions.

## Testing

Add unit coverage for older, equal, and newer server versions, plus invalid versions in either argument.

GitOrigin-RevId: afcc90b56e188df1bf410c69ca238765b4658000

codex-rs/tui/src/update_versions.rs

@@ -16,6 +16,32 @@ pub(crate) fn is_source_build_version(version: &str) -> bool {
     parse_version(version) == Some((0, 0, 0))
 }
 
+/// Whether an official stable TUI release is newer than the connected app server.
+pub(crate) fn is_official_server_older(client: &str, server: &str) -> bool {
+    fn stable_version(version: &str) -> Option<(u64, u64, u64)> {
+        fn component(value: Option<&str>) -> Option<u64> {
+            let value = value?;
+            if value.is_empty()
+                || !value.bytes().all(|byte| byte.is_ascii_digit())
+                || (value.len() > 1 && value.starts_with('0'))
+            {
+                return None;
+            }
+            value.parse().ok()
+        }
+
+        let mut parts = version.split('.');
+        let version = (
+            component(parts.next())?,
+            component(parts.next())?,
+            component(parts.next())?,
+        );
+        (parts.next().is_none() && version != (0, 0, 0)).then_some(version)
+    }
+
+    matches!((stable_version(client), stable_version(server)), (Some(client), Some(server)) if client > server)
+}
+
 fn parse_version(v: &str) -> Option<(u64, u64, u64)> {
     let mut iter = v.trim().split('.');
     let maj = iter.next()?.parse::<u64>().ok()?;
@@ -67,4 +93,26 @@ mod tests {
         assert_eq!(parse_version(" 1.2.3 \n"), Some((1, 2, 3)));
         assert_eq!(is_newer(" 1.2.3 ", "1.2.2"), Some(true));
     }
+
+    #[test]
+    fn official_server_version_comparison() {
+        assert!(is_official_server_older("0.152.1", "0.152.0"));
+        assert!(is_official_server_older("0.153.0", "0.152.1"));
+        assert!(!is_official_server_older("0.152.0", "0.152.0"));
+        assert!(!is_official_server_older("0.152.0", "0.153.0"));
+        for version in [
+            "0.0.0",
+            "0.0.0.0",
+            "0.153.0-alpha.1",
+            "unknown",
+            "0.153",
+            "0.153.0.1",
+            " 0.153.0",
+            "+0.153.0",
+            "0.0153.0",
+        ] {
+            assert!(!is_official_server_older(version, "0.152.0"));
+            assert!(!is_official_server_older("0.153.0", version));
+        }
+    }
 }