fix: print shell completions to stdout by default

docs/handbook.md

@@ -400,9 +400,10 @@ lla completion zsh --output ./_lla
 lla completion zsh --path ~/.zsh/completions/_lla
 ```
 
-Without either option, the command installs to its shell-specific default file.
-`--path` overrides that installed file; `--output` writes the generated script
-to the requested file. Release packages may also include pre-generated assets.
+Without either option, the command prints the script to stdout, so it can be
+redirected or evaluated by your shell. `--path` installs to the specified file;
+`--output` writes the generated script to the requested file. Release packages
+may also include pre-generated assets.
 
 ### Shortcuts
 

lla/src/commands/command_handler.rs

@@ -54,8 +54,12 @@ fn install_completion(
     let mut buf = Vec::new();
     clap_complete::generate(shell, app, env!("CARGO_PKG_NAME"), &mut buf);
 
-    match output_path {
-        Some(path) => {
+    match (output_path, custom_path) {
+        (None, None) => {
+            std::io::stdout().lock().write_all(&buf)?;
+            Ok(())
+        }
+        (Some(path), _) => {
             if let Some(parent) = std::path::Path::new(path).parent() {
                 create_dir_all(parent)?;
             }
@@ -72,75 +76,14 @@ fn install_completion(
             }
             Ok(())
         }
-        None => {
-            let (install_path, post_install_msg) = if let Some(path) = custom_path {
-                (
-                    std::path::PathBuf::from(path),
-                    "Restart your shell to apply changes",
-                )
-            } else {
-                match shell {
-                    clap_complete::Shell::Bash => {
-                        let path = dirs::home_dir()
-                            .map(|h| h.join(".local/share/bash-completion/completions"))
-                            .ok_or_else(|| {
-                                LlaError::Other("Could not determine home directory".into())
-                            })?;
-                        (
-                            path.join("lla"),
-                            "Restart your shell or run 'source ~/.bashrc'",
-                        )
-                    }
-                    clap_complete::Shell::Fish => {
-                        let path = dirs::home_dir()
-                            .map(|h| h.join(".config/fish/completions"))
-                            .ok_or_else(|| {
-                                LlaError::Other("Could not determine home directory".into())
-                            })?;
-                        (
-                            path.join("lla.fish"),
-                            "Restart your shell or run 'source ~/.config/fish/config.fish'",
-                        )
-                    }
-                    clap_complete::Shell::Zsh => {
-                        let path = dirs::home_dir()
-                            .map(|h| h.join(".zsh/completions"))
-                            .ok_or_else(|| {
-                                LlaError::Other("Could not determine home directory".into())
-                            })?;
-                        (
-                            path.join("_lla"),
-                            "Add 'fpath=(~/.zsh/completions $fpath)' to ~/.zshrc and restart your shell",
-                        )
-                    }
-                    clap_complete::Shell::PowerShell => {
-                        let path = dirs::home_dir()
-                            .map(|h| h.join("Documents/WindowsPowerShell"))
-                            .ok_or_else(|| {
-                                LlaError::Other("Could not determine home directory".into())
-                            })?;
-                        (
-                            path.join("lla.ps1"),
-                            "Restart PowerShell or reload your profile",
-                        )
-                    }
-                    clap_complete::Shell::Elvish => {
-                        let path =
-                            dirs::home_dir()
-                                .map(|h| h.join(".elvish/lib"))
-                                .ok_or_else(|| {
-                                    LlaError::Other("Could not determine home directory".into())
-                                })?;
-                        (path.join("lla.elv"), "Restart your shell")
-                    }
-                    _ => return Err(LlaError::Other(format!("Unsupported shell: {:?}", shell))),
-                }
-            };
+        (None, Some(path)) => {
+            let install_path = std::path::Path::new(path);
+            let post_install_msg = "Restart your shell to apply changes";
 
             if let Some(parent) = install_path.parent() {
                 create_dir_all(parent)?;
             }
-            fs::write(&install_path, buf)?;
+            fs::write(install_path, buf)?;
 
             if color_state.is_enabled() {
                 println!(

lla/tests/completions.rs

@@ -0,0 +1,68 @@
+use std::fs;
+use std::process::{Command, Output};
+use tempfile::TempDir;
+
+fn completion(home: &TempDir, shell: &str, options: &[&str]) -> Output {
+    Command::new(env!("CARGO_BIN_EXE_lla"))
+        .env("HOME", home.path())
+        .env("USERPROFILE", home.path())
+        .env("APPDATA", home.path().join("AppData/Roaming"))
+        .env("LOCALAPPDATA", home.path().join("AppData/Local"))
+        .env("XDG_CONFIG_HOME", home.path().join(".config"))
+        .env("NO_COLOR", "1")
+        .current_dir(home.path())
+        .args(["completion", shell])
+        .args(options)
+        .output()
+        .expect("run completion command")
+}
+
+#[test]
+fn completions_default_to_stdout_without_installing_files() {
+    for shell in ["bash", "fish", "zsh", "powershell", "elvish"] {
+        let home = TempDir::new().unwrap();
+        let output = completion(&home, shell, &[]);
+        assert!(output.status.success(), "{shell}: {:?}", output);
+        let script = String::from_utf8(output.stdout).unwrap();
+        assert!(script.contains("lla"), "{shell}: missing completion script");
+        assert!(!script.contains("✓"), "{shell}: status message in script");
+        assert!(output.stderr.is_empty(), "{shell}: {:?}", output.stderr);
+        for path in [
+            ".local/share/bash-completion/completions/lla",
+            ".config/fish/completions/lla.fish",
+            ".zsh/completions/_lla",
+            "Documents/WindowsPowerShell/lla.ps1",
+            ".elvish/lib/lla.elv",
+        ] {
+            assert!(!home.path().join(path).exists(), "{shell}: created {path}");
+        }
+    }
+}
+
+#[test]
+fn explicit_paths_write_the_same_script_as_stdout() {
+    for shell in ["bash", "fish", "zsh", "powershell", "elvish"] {
+        let home = TempDir::new().unwrap();
+        let expected = completion(&home, shell, &[]);
+        assert!(expected.status.success());
+        for option in ["--output", "--path"] {
+            let path = home.path().join(format!("nested/{shell}/{option}"));
+            let output = completion(&home, shell, &[option, path.to_str().unwrap()]);
+            assert!(output.status.success(), "{shell} {option}: {:?}", output);
+            assert_eq!(fs::read(path).unwrap(), expected.stdout);
+        }
+    }
+}
+
+#[test]
+fn output_takes_precedence_over_install_path() {
+    let home = TempDir::new().unwrap();
+    let output = completion(
+        &home,
+        "zsh",
+        &["--path", "install/_lla", "--output", "output/_lla"],
+    );
+    assert!(output.status.success(), "{:?}", output);
+    assert!(home.path().join("output/_lla").is_file());
+    assert!(!home.path().join("install").exists());
+}