feat: add attach config option (#145)

* feat: add attach config option

Currently, auto-attach requires using the -a flag on every smug start
command. This adds an optional 'attach' field to the config file,
allowing per-project control over attachment behavior.

The -a flag still works and takes precedence, so this is backward
compatible.

Example usage in config:
  session: my-project
  attach: true
  windows:
    - name: editor
      commands:
        - vim

* test: add tests for attach config option

Add tests to verify:
- attach: true is parsed correctly
- attach defaults to false when not specified

* docs: add comment for attach config field

* docs: add attach option to README

Author: stefanwalther

README.md

@@ -151,6 +151,10 @@ xyz@localhost:~$ smug start -f ./project.yml -w window1 -w window2
 Configuration files can stored in the `~/.config/smug` directory in the `YAML` format, e.g `~/.config/smug/your_project.yml`.
 You may also create a file named `.smug.yml` in the current working directory, which will be used by default.
 
+### Session-level options
+
+- `attach` - Automatically attach to the session after creation (defaults to `false`). The `-a` flag can also enable attachment.
+
 ### Examples
 
 #### Example 1
@@ -199,6 +203,7 @@ windows:
 
 ```yaml
 session: blog
+attach: true # Automatically attach to this session
 
 root: ~/Code/blog
 

config.go

@@ -41,7 +41,10 @@ type Window struct {
 type Config struct {
 	SendKeysTimeout int    `yaml:"sendkeys_timeout"`
 	Session         string `yaml:"session"`
-	TmuxOptions     `yaml:"tmux_options"`
+	// Attach controls whether the session automatically attaches after creation.
+	// The -a/--attach CLI flag can also enable attachment.
+	Attach      bool              `yaml:"attach,omitempty"`
+	TmuxOptions `yaml:"tmux_options"`
 	Env             map[string]string `yaml:"env"`
 	Root            string            `yaml:"root"`
 	BeforeStart     []string          `yaml:"before_start"`

config_test.go

@@ -58,3 +58,40 @@ windows:
 		t.Fatalf("expected %v, got %v", expected, config)
 	}
 }
+
+func TestParseConfigWithAttach(t *testing.T) {
+	yaml := `
+session: test
+attach: true
+windows:
+  - name: editor
+    commands:
+      - vim`
+
+	config, err := ParseConfig(yaml, map[string]string{})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !config.Attach {
+		t.Fatal("expected attach to be true, got false")
+	}
+}
+
+func TestParseConfigWithoutAttach(t *testing.T) {
+	yaml := `
+session: test
+windows:
+  - name: editor
+    commands:
+      - vim`
+
+	config, err := ParseConfig(yaml, map[string]string{})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if config.Attach {
+		t.Fatal("expected attach to be false by default, got true")
+	}
+}

smug.go

@@ -108,7 +108,7 @@ func (smug Smug) Start(config *Config, options *Options, context Context) error
 	sessionExists := smug.tmux.SessionExists(sessionName)
 	sessionRoot := ExpandPath(config.Root)
 	windows := options.Windows
-	attach := options.Attach
+	attach := options.Attach || config.Attach
 
 	if !sessionExists && !createWindowsInsideCurrSession {
 		err := smug.execShellCommands(config.BeforeStart, sessionRoot)