Clarify update checks for releases

src/bin/dosh-client.rs

@@ -1503,7 +1503,54 @@ fn latest_release_download_url(repo: &str, artifact: &str) -> Option<String> {
     Some(format!("{web}/releases/latest/download/{artifact}"))
 }
 
-fn latest_release_tag_download_url(repo: &str, artifact: &str) -> Result<Option<String>> {
+fn release_tag_from_effective_url(web: &str, effective: &str) -> Option<String> {
+    let prefix = format!("{web}/releases/tag/");
+    let tag = effective.strip_prefix(&prefix)?;
+    if tag.is_empty() {
+        None
+    } else {
+        Some(tag.to_string())
+    }
+}
+
+fn release_version_from_tag(tag: &str) -> &str {
+    tag.strip_prefix('v').unwrap_or(tag)
+}
+
+fn update_version_status(local: &str, latest: &str) -> &'static str {
+    match compare_dotted_versions(latest, local) {
+        std::cmp::Ordering::Equal => "current",
+        std::cmp::Ordering::Greater => "update available",
+        std::cmp::Ordering::Less => "different",
+    }
+}
+
+fn compare_dotted_versions(left: &str, right: &str) -> std::cmp::Ordering {
+    let left = parse_dotted_version(left);
+    let right = parse_dotted_version(right);
+    let width = left.len().max(right.len());
+    for index in 0..width {
+        let ordering = left
+            .get(index)
+            .copied()
+            .unwrap_or(0)
+            .cmp(&right.get(index).copied().unwrap_or(0));
+        if ordering != std::cmp::Ordering::Equal {
+            return ordering;
+        }
+    }
+    std::cmp::Ordering::Equal
+}
+
+fn parse_dotted_version(version: &str) -> Vec<u64> {
+    version
+        .split(|byte: char| !byte.is_ascii_digit())
+        .filter(|part| !part.is_empty())
+        .map(|part| part.parse::<u64>().unwrap_or(0))
+        .collect()
+}
+
+fn latest_release_tag(repo: &str) -> Result<Option<String>> {
     let web = repo
         .strip_suffix(".git")
         .unwrap_or(repo)
@@ -1525,14 +1572,18 @@ fn latest_release_tag_download_url(repo: &str, artifact: &str) -> Result<Option<
         return Ok(None);
     }
     let effective = String::from_utf8_lossy(&output.stdout);
-    let prefix = format!("{web}/releases/tag/");
-    let Some(tag) = effective.strip_prefix(&prefix) else {
-        return Ok(None);
-    };
-    if tag.is_empty() {
+    Ok(release_tag_from_effective_url(web, &effective))
+}
+
+fn latest_release_tag_download_url(repo: &str, artifact: &str) -> Result<Option<String>> {
+    let web = repo
+        .strip_suffix(".git")
+        .unwrap_or(repo)
+        .trim_end_matches('/');
+    if !web.starts_with("http://") && !web.starts_with("https://") {
         return Ok(None);
     }
-    Ok(Some(format!("{web}/releases/download/{tag}/{artifact}")))
+    Ok(latest_release_tag(repo)?.map(|tag| format!("{web}/releases/download/{tag}/{artifact}")))
 }
 
 fn url_reachable(url: &str) -> Result<bool> {
@@ -1556,9 +1607,20 @@ fn run_update(config: &dosh::config::ClientConfig, check_only: bool) -> Result<(
     let installer = format!("{raw_base}/raw/branch/main/install.sh");
     let artifact = release_artifact_name();
     if check_only {
-        println!("dosh {}", env!("CARGO_PKG_VERSION"));
+        let local_version = env!("CARGO_PKG_VERSION");
+        println!("dosh {local_version}");
         println!("repo: {repo}");
         println!("installer: {installer}");
+        match latest_release_tag(&repo)? {
+            Some(tag) => {
+                let latest_version = release_version_from_tag(&tag);
+                println!(
+                    "latest: {latest_version} ({})",
+                    update_version_status(local_version, latest_version)
+                );
+            }
+            None => println!("latest: unknown"),
+        }
         if let Some(latest_url) = latest_release_download_url(&repo, artifact) {
             let mut status = "missing";
             let mut display_url = latest_url.clone();
@@ -5557,12 +5619,13 @@ mod tests {
         load_first_native_identity_with_prompt, parse_dynamic_forward, parse_escape_key,
         parse_local_forward, parse_remote_forward, parse_ssh_config, post_submit_hold_duration,
         queue_pending_user_input, raw_contains_host_table, recv_response_until, refresh_live_addr,
-        render_status_clear, render_status_overlay, requested_env, resolved_startup_command,
-        retransmit_stream_opens, rewrite_forward_command, selected_predict_mode, selected_udp_host,
-        server_version_mismatch, should_hold_during_startup_gate, should_hold_post_submit_input,
-        split_after_command_submit, ssh_destination_host, ssh_username, ssh_with_user,
-        startup_command, status_ssh_target, strip_stale_mouse_reports, toml_bare_key_or_quoted,
-        update_check_requested, valid_forward_host,
+        release_tag_from_effective_url, release_version_from_tag, render_status_clear,
+        render_status_overlay, requested_env, resolved_startup_command, retransmit_stream_opens,
+        rewrite_forward_command, selected_predict_mode, selected_udp_host, server_version_mismatch,
+        should_hold_during_startup_gate, should_hold_post_submit_input, split_after_command_submit,
+        ssh_destination_host, ssh_username, ssh_with_user, startup_command, status_ssh_target,
+        strip_stale_mouse_reports, toml_bare_key_or_quoted, update_check_requested,
+        update_version_status, valid_forward_host,
     };
     use dosh::config::{ClientConfig, CommandExtension, HostConfig};
     use dosh::native::EnvVar;
@@ -6435,6 +6498,28 @@ mod tests {
         );
     }
 
+    #[test]
+    fn release_tag_parses_effective_latest_url() {
+        assert_eq!(
+            release_tag_from_effective_url(
+                "https://example.com/owner/dosh",
+                "https://example.com/owner/dosh/releases/tag/v1.0.0"
+            )
+            .as_deref(),
+            Some("v1.0.0")
+        );
+        assert_eq!(release_version_from_tag("v1.0.0"), "1.0.0");
+        assert_eq!(release_version_from_tag("2026.06.28"), "2026.06.28");
+        assert!(release_tag_from_effective_url("https://example.com/owner/dosh", "").is_none());
+    }
+
+    #[test]
+    fn update_version_status_compares_numeric_parts() {
+        assert_eq!(update_version_status("0.1.5", "0.1.5"), "current");
+        assert_eq!(update_version_status("0.1.9", "0.1.10"), "update available");
+        assert_eq!(update_version_status("1.0.0", "0.9.9"), "different");
+    }
+
     #[test]
     fn resolved_startup_command_expands_global_extension() {
         let mut config = ClientConfig::default();