diff --git a/go.mod b/go.mod
index a8225e5..c821c5f 100644
--- a/go.mod
+++ b/go.mod
@@ -4,6 +4,7 @@ go 1.25.0
 
 require (
 	github.com/gin-gonic/gin v1.12.0
+	github.com/gorilla/websocket v1.5.3
 	gopkg.in/yaml.v3 v3.0.1
 )
 
diff --git a/go.sum b/go.sum
index bb72904..f3880d6 100644
--- a/go.sum
+++ b/go.sum
@@ -30,6 +30,8 @@ github.com/goccy/go-yaml v1.19.2/go.mod h1:XBurs7gK8ATbW4ZPGKgcbrY1Br56PdM69F7Lk
 github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
 github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
 github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
+github.com/gorilla/websocket v1.5.3 h1:saDtZ6Pbx/0u+bgYQ3q96pZgCzfhKXGPqt7kZ72aNNg=
+github.com/gorilla/websocket v1.5.3/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
 github.com/json-iterator/go v1.1.12 h1:PV8peI4a0ysnczrg+LtxykD8LfKY9ML6u2jnxaEnrnM=
 github.com/json-iterator/go v1.1.12/go.mod h1:e30LSqwooZae/UwlEbR2852Gd8hjQvJoHmT4TnhNGBo=
 github.com/klauspost/cpuid/v2 v2.4.0 h1:S6Hrbc7+ywsr0r+RLapfGBHfyefhCTwEh3A0tV913Dw=
diff --git a/internal/api/process_handler.go b/internal/api/process_handler.go
index 82008a9..9b0e8c6 100644
--- a/internal/api/process_handler.go
+++ b/internal/api/process_handler.go
@@ -1,18 +1,31 @@
 package api
 
 import (
+	"fmt"
 	"net/http"
+	"sync"
+	"time"
 
 	"codespace/internal/model"
+	"codespace/internal/process"
 	"codespace/internal/service"
+	"codespace/internal/util"
 
 	"github.com/gin-gonic/gin"
+	"github.com/gorilla/websocket"
 )
 
 type processHandler struct {
 	svc *service.ProcessService
 }
 
+func exitBanner(exit process.ExitInfo) string {
+	if exit.Signal != "" {
+		return fmt.Sprintf("\r\n[process exited: signal %s]\r\n", exit.Signal)
+	}
+	return fmt.Sprintf("\r\n[process exited with code %d]\r\n", exit.Code)
+}
+
 func (h *processHandler) start(c *gin.Context) {
 	id := c.Param("id")
 	if err := h.svc.Start(id); err != nil {
@@ -53,3 +66,92 @@ func (h *processHandler) status(c *gin.Context) {
 		PID:         status.PID,
 	})
 }
+
+func (h *processHandler) ws(c *gin.Context) {
+	id := c.Param("id")
+
+	stdin, err := h.svc.Input(id)
+	if err != nil {
+		if util.CodeOf(err) == util.CodeNotFound {
+			c.JSON(409, gin.H{"error": "process not running"})
+			return
+		}
+		writeError(c, err)
+		return
+	}
+
+	sub, err := h.svc.Subscribe(id)
+	if err != nil {
+		writeError(c, err)
+		return
+	}
+
+	exit, _ := h.svc.ExitStatus(id)
+
+	upgrader := websocket.Upgrader{
+		CheckOrigin:     func(r *http.Request) bool { return true },
+		ReadBufferSize:  4096,
+		WriteBufferSize: 4096,
+	}
+
+	conn, err := upgrader.Upgrade(c.Writer, c.Request, nil)
+	if err != nil {
+		return
+	}
+
+	done := make(chan struct{})
+	var closeOnce sync.Once
+	closeAll := func() {
+		closeOnce.Do(func() {
+			sub.Close()
+			conn.Close()
+			stdin.Close()
+			close(done)
+		})
+	}
+
+	go func() {
+		ticker := time.NewTicker(30 * time.Second)
+		defer ticker.Stop()
+		for {
+			select {
+			case <-done:
+				return
+			case <-ticker.C:
+				if err := conn.WriteControl(websocket.PingMessage, nil, time.Now().Add(5*time.Second)); err != nil {
+					closeAll()
+					return
+				}
+			case chunk, ok := <-sub.Output():
+				if !ok {
+					banner := exitBanner(exit)
+					conn.WriteMessage(websocket.TextMessage, []byte(banner))
+					conn.WriteMessage(websocket.CloseMessage, websocket.FormatCloseMessage(websocket.CloseNormalClosure, ""))
+					closeAll()
+					return
+				}
+				if err := conn.WriteMessage(websocket.TextMessage, chunk); err != nil {
+					closeAll()
+					return
+				}
+			}
+		}
+	}()
+
+	conn.SetReadLimit(1 << 20)
+	conn.SetReadDeadline(time.Now().Add(60 * time.Second))
+	conn.SetPongHandler(func(string) error {
+		conn.SetReadDeadline(time.Now().Add(60 * time.Second))
+		return nil
+	})
+	for {
+		mt, data, err := conn.ReadMessage()
+		if err != nil {
+			break
+		}
+		if mt == websocket.TextMessage {
+			stdin.Write(data)
+		}
+	}
+	closeAll()
+}
diff --git a/internal/api/process_ws_test.go b/internal/api/process_ws_test.go
new file mode 100644
index 0000000..a84d2ab
--- /dev/null
+++ b/internal/api/process_ws_test.go
@@ -0,0 +1,90 @@
+package api
+
+import (
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+
+	"codespace/internal/process"
+	"codespace/internal/service"
+	"codespace/internal/workspace"
+
+	"github.com/gin-gonic/gin"
+	"github.com/gorilla/websocket"
+)
+
+func TestProcessWS(t *testing.T) {
+	tmpDir := t.TempDir()
+
+	opencodePath := filepath.Join(tmpDir, "opencode")
+	script := []byte("#!/bin/sh\nread line\necho \"got: $line\"\nsleep 0.1\nexit 0\n")
+	if err := os.WriteFile(opencodePath, script, 0o755); err != nil {
+		t.Fatalf("write fake opencode: %v", err)
+	}
+
+	wsRoot := filepath.Join(tmpDir, "workspaces")
+	wsMgr := workspace.NewLocalManager(wsRoot)
+	procMgr := process.NewManager(opencodePath)
+	wsSvc := service.NewWorkspaceService(wsMgr, procMgr, nil)
+	fileSvc := service.NewFileService(wsMgr, 1<<20)
+	procSvc := service.NewProcessService(wsMgr, procMgr, nil)
+
+	r := NewRouter(wsSvc, fileSvc, procSvc, nil, gin.TestMode)
+	srv := httptest.NewServer(r)
+	defer srv.Close()
+
+	ws, err := wsSvc.Create("wstest")
+	if err != nil {
+		t.Fatalf("create workspace: %v", err)
+	}
+	t.Cleanup(func() {
+		if err := wsSvc.Delete(ws.ID); err != nil {
+			t.Logf("cleanup delete workspace: %v", err)
+		}
+	})
+
+	if err := procSvc.Start(ws.ID); err != nil {
+		t.Fatalf("start process: %v", err)
+	}
+
+	wsURL := "ws" + strings.TrimPrefix(srv.URL, "http") + "/api/workspaces/" + ws.ID + "/process/ws"
+	conn, _, err := websocket.DefaultDialer.Dial(wsURL, nil)
+	if err != nil {
+		t.Fatalf("dial websocket: %v", err)
+	}
+	defer conn.Close()
+
+	if err := conn.WriteMessage(websocket.TextMessage, []byte("hello\n")); err != nil {
+		t.Fatalf("write message: %v", err)
+	}
+
+	if err := conn.SetReadDeadline(time.Now().Add(3 * time.Second)); err != nil {
+		t.Fatalf("set read deadline: %v", err)
+	}
+
+	var gotEcho, gotExit bool
+	for {
+		_, data, err := conn.ReadMessage()
+		if err != nil {
+			break
+		}
+		text := string(data)
+		if strings.Contains(text, "got: hello") {
+			gotEcho = true
+		}
+		if strings.Contains(text, "[process exited") {
+			gotExit = true
+			break
+		}
+	}
+
+	if !gotEcho {
+		t.Fatal("did not receive echo frame containing \"got: hello\"")
+	}
+	if !gotExit {
+		t.Fatal("did not receive exit banner frame")
+	}
+}
diff --git a/internal/api/router.go b/internal/api/router.go
index e5ad6d2..6ba9183 100644
--- a/internal/api/router.go
+++ b/internal/api/router.go
@@ -40,6 +40,7 @@ func NewRouter(workspaces *service.WorkspaceService, files *service.FileService,
 	api.POST("/workspaces/:id/process/stop", procHandler.stop)
 	api.POST("/workspaces/:id/process/restart", procHandler.restart)
 	api.GET("/workspaces/:id/process/status", procHandler.status)
+	api.GET("/workspaces/:id/process/ws", procHandler.ws)
 
 	return r
 }