feat: Add stream option for real-time output without requiring TTY

docs/mdbook/SUMMARY.md

@@ -86,6 +86,7 @@
       - [`fail_text`](./configuration/fail_text.md)
       - [`stage_fixed`](./configuration/stage_fixed.md)
       - [`interactive`](./configuration/interactive.md)
+      - [`stream`](./configuration/stream.md)
       - [`use_stdin`](./configuration/use_stdin.md)
     - [`commands`](./configuration/Commands.md)
       - [`run`](./configuration/run.md)
@@ -101,6 +102,7 @@
       - [`fail_text`](./configuration/fail_text.md)
       - [`stage_fixed`](./configuration/stage_fixed.md)
       - [`interactive`](./configuration/interactive.md)
+      - [`stream`](./configuration/stream.md)
       - [`use_stdin`](./configuration/use_stdin.md)
       - [`priority`](./configuration/priority.md)
     - [`scripts`](./configuration/Scripts.md)
@@ -112,6 +114,7 @@
       - [`fail_text`](./configuration/fail_text.md)
       - [`stage_fixed`](./configuration/stage_fixed.md)
       - [`interactive`](./configuration/interactive.md)
+      - [`stream`](./configuration/stream.md)
       - [`use_stdin`](./configuration/use_stdin.md)
       - [`priority`](./configuration/priority.md)
 - [ENV variables](./usage/env.md)

docs/mdbook/configuration/stream.md

@@ -0,0 +1,37 @@
+## `stream`
+
+**Default: `false`**
+
+Enable real-time streaming output for commands or scripts without requiring a TTY. This is useful when you want to see command output as it happens in non-interactive environments like VS Code's git commit interface, CI/CD pipelines, or any environment where a TTY is not available.
+
+Unlike [`interactive`](./interactive.md), `stream` does not attempt to open `/dev/tty` for user input, making it work seamlessly in environments without TTY access.
+
+**Example**
+
+Use this option when you want to see real-time output from long-running commands or scripts, such as linters or test runners, even when running commits from editors or IDEs:
+
+```yml
+# lefthook.yml
+pre-commit:
+  commands:
+    tests:
+      run: npm test
+      stream: true
+    lint:
+      run: npm run lint
+      stream: true
+```
+
+**Comparison with other options**
+
+- `stream: true` - Streams output in real-time, no TTY required, no user input
+- `interactive: true` - Requires TTY for user input, will fail if TTY is unavailable
+- `use_stdin: true` - Passes stdin to the command but doesn't control output streaming
+- Default (all false) - Uses pseudo-TTY for output buffering
+
+**When to use**
+
+- You want real-time output visibility
+- You're running hooks from non-TTY environments (VS Code, GitHub Desktop, etc.)
+- Your command produces output you want to see immediately
+- You don't need user input during execution

internal/config/command.go

@@ -27,6 +27,7 @@ type Command struct {
 
 	Priority    int  `json:"priority,omitempty"    mapstructure:"priority"    toml:"priority,omitempty"    yaml:",omitempty"`
 	Interactive bool `json:"interactive,omitempty" mapstructure:"interactive" toml:"interactive,omitempty" yaml:",omitempty"`
+	Stream      bool `json:"stream,omitempty"      mapstructure:"stream"      toml:"stream,omitempty"      yaml:",omitempty"`
 	UseStdin    bool `json:"use_stdin,omitempty"   koanf:"use_stdin"          mapstructure:"use_stdin"     toml:"use_stdin,omitempty"   yaml:"use_stdin,omitempty"`
 	StageFixed  bool `json:"stage_fixed,omitempty" koanf:"stage_fixed"        mapstructure:"stage_fixed"   toml:"stage_fixed,omitempty" yaml:"stage_fixed,omitempty"`
 }
@@ -45,6 +46,7 @@ func CommandsToJobs(commands map[string]*Command) []*Job {
 			FileTypes:   command.FileTypes,
 			Env:         command.Env,
 			Interactive: command.Interactive,
+			Stream:      command.Stream,
 			UseStdin:    command.UseStdin,
 			StageFixed:  command.StageFixed,
 			Exclude:     command.Exclude,

internal/config/job.go

@@ -17,6 +17,7 @@ type Job struct {
 	Env map[string]string `json:"env,omitempty" mapstructure:"env" toml:"env,omitempty" yaml:",omitempty"`
 
 	Interactive bool `json:"interactive,omitempty" mapstructure:"interactive" toml:"interactive,omitempty" yaml:",omitempty"`
+	Stream      bool `json:"stream,omitempty"      mapstructure:"stream"      toml:"stream,omitempty"      yaml:",omitempty"`
 	UseStdin    bool `json:"use_stdin,omitempty"   koanf:"use_stdin"          mapstructure:"use_stdin"     toml:"use_stdin,omitempty"   yaml:"use_stdin,omitempty"`
 	StageFixed  bool `json:"stage_fixed,omitempty" koanf:"stage_fixed"        mapstructure:"stage_fixed"   toml:"stage_fixed,omitempty" yaml:"stage_fixed,omitempty"`
 

internal/config/jsonschema.json

@@ -93,6 +93,9 @@
         "interactive": {
           "type": "boolean"
         },
+        "stream": {
+          "type": "boolean"
+        },
         "use_stdin": {
           "type": "boolean"
         },
@@ -300,6 +303,9 @@
         "interactive": {
           "type": "boolean"
         },
+        "stream": {
+          "type": "boolean"
+        },
         "use_stdin": {
           "type": "boolean"
         },
@@ -421,6 +427,9 @@
         "interactive": {
           "type": "boolean"
         },
+        "stream": {
+          "type": "boolean"
+        },
         "use_stdin": {
           "type": "boolean"
         },
@@ -432,7 +441,7 @@
       "type": "object"
     }
   },
-  "$comment": "Last updated on 2025.10.24.",
+  "$comment": "Last updated on 2025.10.31.",
   "properties": {
     "min_version": {
       "type": "string",

internal/config/script.go

@@ -19,6 +19,7 @@ type Script struct {
 
 	FailText    string `json:"fail_text,omitempty"   koanf:"fail_text"          mapstructure:"fail_text"     toml:"fail_text,omitempty"   yaml:"fail_text,omitempty"`
 	Interactive bool   `json:"interactive,omitempty" mapstructure:"interactive" toml:"interactive,omitempty" yaml:",omitempty"`
+	Stream      bool   `json:"stream,omitempty"      mapstructure:"stream"      toml:"stream,omitempty"      yaml:",omitempty"`
 	UseStdin    bool   `json:"use_stdin,omitempty"   koanf:"use_stdin"          mapstructure:"use_stdin"     toml:"use_stdin,omitempty"   yaml:"use_stdin,omitempty"`
 	StageFixed  bool   `json:"stage_fixed,omitempty" koanf:"stage_fixed"        mapstructure:"stage_fixed"   toml:"stage_fixed,omitempty" yaml:"stage_fixed,omitempty"`
 }
@@ -34,6 +35,7 @@ func ScriptsToJobs(scripts map[string]*Script) []*Job {
 			Tags:        script.Tags,
 			Env:         script.Env,
 			Interactive: script.Interactive,
+			Stream:      script.Stream,
 			UseStdin:    script.UseStdin,
 			StageFixed:  script.StageFixed,
 			Skip:        script.Skip,

internal/run/controller/exec/exec_unix.go

@@ -20,15 +20,16 @@ import (
 type CommandExecutor struct{}
 
 type executeArgs struct {
-	in                    io.Reader
-	out                   io.Writer
-	envs                  []string
-	root                  string
-	interactive, useStdin bool
+	in                            io.Reader
+	out                           io.Writer
+	envs                          []string
+	root                          string
+	interactive, stream, useStdin bool
 }
 
 func (e CommandExecutor) Execute(ctx context.Context, opts Options, in io.Reader, out io.Writer) error {
-	if opts.Interactive && !isatty.IsTerminal(os.Stdin.Fd()) {
+	// Only try to open TTY for interactive mode (user input needed), not for stream mode
+	if opts.Interactive && !opts.Stream && !isatty.IsTerminal(os.Stdin.Fd()) {
 		tty, err := os.Open("/dev/tty")
 		if err == nil {
 			defer func() {
@@ -63,6 +64,7 @@ func (e CommandExecutor) Execute(ctx context.Context, opts Options, in io.Reader
 		envs:        envs,
 		root:        root,
 		interactive: opts.Interactive,
+		stream:      opts.Stream,
 		useStdin:    opts.UseStdin,
 	}
 
@@ -83,7 +85,7 @@ func (e CommandExecutor) execute(ctx context.Context, cmdstr string, args *execu
 	command.Dir = args.root
 	command.Env = append(os.Environ(), args.envs...)
 
-	if args.interactive || args.useStdin {
+	if args.interactive || args.stream || args.useStdin {
 		command.Stdout = args.out
 		command.Stdin = args.in
 		command.Stderr = os.Stderr

internal/run/controller/exec/exec_windows.go

@@ -25,7 +25,8 @@ type executeArgs struct {
 }
 
 func (e CommandExecutor) Execute(ctx context.Context, opts Options, in io.Reader, out io.Writer) error {
-	if opts.Interactive && !isatty.IsTerminal(os.Stdin.Fd()) {
+	// Only try to open TTY for interactive mode (user input needed), not for stream mode
+	if opts.Interactive && !opts.Stream && !isatty.IsTerminal(os.Stdin.Fd()) {
 		tty, err := tty.Open()
 		if err == nil {
 			defer tty.Close()

internal/run/controller/exec/executor.go

@@ -7,10 +7,10 @@ import (
 
 // Options contains the data that controls the execution.
 type Options struct {
-	Root                  string
-	Commands              []string
-	Env                   map[string]string
-	Interactive, UseStdin bool
+	Root                          string
+	Commands                      []string
+	Env                           map[string]string
+	Interactive, Stream, UseStdin bool
 }
 
 // Executor provides an interface for command execution.

internal/run/controller/job.go

@@ -131,6 +131,7 @@ func (c *Controller) runSingleJob(ctx context.Context, scope *scope, id string,
 		Root:        filepath.Join(c.git.RootPath, scope.root),
 		Commands:    commands,
 		Interactive: job.Interactive && !scope.opts.DisableTTY,
+		Stream:      job.Stream,
 		UseStdin:    job.UseStdin,
 		Env:         env,
 	})

schema.json

@@ -93,6 +93,9 @@
         "interactive": {
           "type": "boolean"
         },
+        "stream": {
+          "type": "boolean"
+        },
         "use_stdin": {
           "type": "boolean"
         },
@@ -300,6 +303,9 @@
         "interactive": {
           "type": "boolean"
         },
+        "stream": {
+          "type": "boolean"
+        },
         "use_stdin": {
           "type": "boolean"
         },
@@ -421,6 +427,9 @@
         "interactive": {
           "type": "boolean"
         },
+        "stream": {
+          "type": "boolean"
+        },
         "use_stdin": {
           "type": "boolean"
         },
@@ -432,7 +441,7 @@
       "type": "object"
     }
   },
-  "$comment": "Last updated on 2025.10.24.",
+  "$comment": "Last updated on 2025.10.31.",
   "properties": {
     "min_version": {
       "type": "string",