feat: add self-update command (#13)

- Add 'self-update' command with --check flag
- Query GitHub for latest gitclaw release
- Download and replace current binary atomically
- Support for all platforms (Linux, macOS, Windows)
- Backup current binary before update (rollback on failure)

Part of v0.3.0 phase 2 (self-update).

Author: clawdeeo

AGENTS.md

@@ -284,6 +284,41 @@ let file = fs::read(&path)?;  // Less helpful
 
 ---
 
+### Code Formatting Rules
+
+**Spacing for multi-line code blocks:**
+- Use blank line *after* multi-line code blocks (if/while/match/fn bodies spanning multiple lines)
+- Single-line statements don't need trailing blank line
+- Opening brace on same line for functions, structs, enums
+
+**Example:**
+```rust
+// Good: no blank line after single-line if
+if condition { do_something(); }
+let x = 1;
+
+// Good: blank line after multi-line if
+if condition {
+    do_first();
+    do_second();
+}
+
+let y = 2;
+
+// Good: no blank line within single expressions
+let result = match value {
+    Some(v) => process(v),
+    None => default(),
+};
+```
+
+**Avoid:**
+- Excessive blank lines
+- Comments that restate the obvious
+- "What" comments instead of "why" comments
+
+---
+
 ## Resources
 
 - [Rust API Guidelines](https://rust-lang.github.io/api-guidelines/)

src/cli.rs

@@ -39,4 +39,10 @@ pub enum Commands {
         #[arg(value_enum)]
         shell: Shell,
     },
+    /// Update gitclaw itself
+    SelfUpdate {
+        /// Only check for updates, don't install
+        #[arg(long)]
+        check: bool,
+    },
 }

src/lib.rs

@@ -5,4 +5,5 @@ pub mod github;
 pub mod install;
 pub mod platform;
 pub mod registry;
+pub mod self_update;
 pub mod util;

src/main.rs

@@ -7,6 +7,7 @@ mod github;
 mod install;
 mod platform;
 mod registry;
+mod self_update;
 mod util;
 
 // Extract module as a directory
@@ -76,6 +77,13 @@ async fn run(cli: Cli, config: Config) -> anyhow::Result<()> {
             let name = cmd.get_name().to_string();
             generate(shell, &mut cmd, name, &mut std::io::stdout());
         }
+        Commands::SelfUpdate { check } => {
+            if check {
+                self_update::check_for_update(&config).await?
+            } else {
+                self_update::perform_update(&config).await?
+            }
+        }
     }
 
     Ok(())

src/self_update.rs

@@ -0,0 +1,155 @@
+use anyhow::{anyhow, bail, Context, Result};
+use std::env;
+use std::path::PathBuf;
+
+use crate::config::Config;
+use crate::extract::extract_archive;
+use crate::github::{find_matching_asset, GithubClient, Platform};
+
+const REPO_OWNER: &str = "clawdeeo";
+const REPO_NAME: &str = "gitclaw";
+
+/// Get the current executable path
+fn current_executable() -> Result<PathBuf> {
+    env::current_exe().context("Failed to get current executable path")
+}
+
+/// Get the current version from Cargo.toml
+fn current_version() -> String {
+    env!("CARGO_PKG_VERSION").to_string()
+}
+
+/// Check for updates without installing
+pub async fn check_for_update(config: &Config) -> Result<()> {
+    let client = GithubClient::new(config.github_token.clone())?;
+    let release = client.get_release(REPO_OWNER, REPO_NAME, "latest").await?;
+
+    let current = current_version();
+    let latest = release.tag_name.trim_start_matches('v').to_string();
+
+    println!("Current version: {}", current);
+    println!("Latest version:  {}", latest);
+
+    if latest == current {
+        println!("gitclaw is up to date!");
+    } else {
+        println!("Update available: {} -> {}", current, latest);
+        println!("Run 'gitclaw self-update' to install");
+    }
+
+    Ok(())
+}
+
+/// Perform self-update
+pub async fn perform_update(config: &Config) -> Result<()> {
+    let client = GithubClient::new(config.github_token.clone())?;
+    let release = client.get_release(REPO_OWNER, REPO_NAME, "latest").await?;
+
+    let current = current_version();
+    let latest = release.tag_name.trim_start_matches('v').to_string();
+
+    if latest == current {
+        println!("gitclaw is already at the latest version ({})", current);
+        return Ok(());
+    }
+
+    println!("Updating gitclaw: {} -> {}", current, latest);
+
+    // Find matching asset for current platform
+    let platform = Platform::current()?;
+    let asset = find_matching_asset(&release, platform)
+        .map_err(|_| anyhow!("No suitable asset found for platform: {}", platform))?;
+
+    if !config.output.quiet {
+        println!("Downloading: {}", asset.name);
+    }
+
+    // Download to temp location
+    let temp_dir = std::env::temp_dir().join("gitclaw-self-update");
+    std::fs::create_dir_all(&temp_dir)?;
+    let download_path = temp_dir.join(&asset.name);
+
+    client
+        .download_asset(asset, &download_path, config.download.show_progress)
+        .await?;
+
+    // Get current executable path
+    let current_exe = current_executable()?;
+
+    // Handle based on archive type vs direct binary
+    if asset.name.ends_with(".tar.gz")
+        || asset.name.ends_with(".zip")
+        || asset.name.ends_with(".tar.xz")
+    {
+        let extract_dir = temp_dir.join("extracted");
+        extract_archive(&download_path, &extract_dir, true)?;
+        let new_binary = find_binary(&extract_dir, REPO_NAME)?;
+        replace_binary(&new_binary, &current_exe)?;
+    } else {
+        replace_binary(&download_path, &current_exe)?;
+    }
+    let _ = std::fs::remove_dir_all(&temp_dir);
+    println!("gitclaw updated successfully to {}", latest);
+    Ok(())
+}
+
+/// Find binary in extracted directory
+fn find_binary(dir: &std::path::Path, name: &str) -> Result<PathBuf> {
+    use walkdir::WalkDir;
+
+    for entry in WalkDir::new(dir).max_depth(2) {
+        let entry = entry?;
+        if !entry.file_type().is_file() {
+            continue;
+        }
+        let file_name = entry
+            .path()
+            .file_stem()
+            .unwrap_or_default()
+            .to_string_lossy();
+        if file_name == name {
+            return Ok(entry.path().to_path_buf());
+        }
+    }
+    bail!("Binary '{}' not found in extracted archive", name)
+}
+
+/// Replace current binary with new one
+#[cfg(unix)]
+fn replace_binary(new: &std::path::Path, current: &std::path::Path) -> Result<()> {
+    use std::os::unix::fs::PermissionsExt;
+
+    // On Unix: write to temp file, then rename (atomic)
+    let backup = current.with_extension("backup");
+    std::fs::rename(current, &backup)?;
+    match std::fs::copy(new, current) {
+        Ok(_) => {
+            let mut perms = std::fs::metadata(current)?.permissions();
+            perms.set_mode(0o755);
+            std::fs::set_permissions(current, perms)?;
+            let _ = std::fs::remove_file(&backup);
+            Ok(())
+        }
+        Err(e) => {
+            let _ = std::fs::rename(&backup, current);
+            bail!("Failed to install new binary: {}", e)
+        }
+    }
+}
+
+#[cfg(windows)]
+fn replace_binary(new: &std::path::Path, current: &std::path::Path) -> Result<()> {
+    // On Windows: rename current (in-use files can't be overwritten)
+    let backup = current.with_extension("exe.backup");
+    std::fs::rename(current, &backup)?;
+    match std::fs::copy(new, current) {
+        Ok(_) => {
+            let _ = std::fs::remove_file(&backup);
+            Ok(())
+        }
+        Err(e) => {
+            let _ = std::fs::rename(&backup, current);
+            bail!("Failed to install new binary: {}", e)
+        }
+    }
+}