diff --git a/agent/sandbox/v2/opencode/command.go b/agent/sandbox/v2/opencode/command.go
index 63f600bd..c1d8405d 100644
--- a/agent/sandbox/v2/opencode/command.go
+++ b/agent/sandbox/v2/opencode/command.go
@@ -66,7 +66,7 @@ func (r *Runner) buildCommand(req *types.StreamRequest, p platform, attachmentPa
 
 	stdinMsg := buildStdinMessage(req.Messages, attachmentPaths)
 
-	script := shellQuote("opencode", args...)
+	script := shellQuoteForPlatform(p, "opencode", args...)
 
 	return command{
 		shell:   p.ShellCmd(script),
@@ -255,12 +255,18 @@ func buildSandboxEnvPrompt(p platform, workDir string) string {
 		shell = "bash"
 	}
 
+	envVarSyntax := "$VAR_NAME"
+	if osName == "windows" {
+		envVarSyntax = "$env:VAR_NAME"
+	}
+
 	return fmt.Sprintf(`## Sandbox Environment
 
 - **Operating System**: %[2]s
 - **Shell**: %[3]s
 - **Working Directory**: %[1]s
 - **File Access**: You have full read/write access to %[1]s
+- **Environment variable syntax**: `+"`%[4]s`"+`
 
 ## User Attachments
 
@@ -268,7 +274,7 @@ User-uploaded files are placed in %[1]s/.attachments/{chatID}/
 Each chat session has its own subdirectory.
 When the user attaches files, their paths are listed at the top of the message.
 **Read these files yourself** using the Read or Bash tool — they are NOT passed as CLI arguments.
-`, workDir, osName, shell)
+`, workDir, osName, shell, envVarSyntax)
 }
 
 func getProviderPrefix(conn connector.Connector) string {
@@ -302,7 +308,17 @@ func getRoleConnectors(req *types.StreamRequest) map[string]*types.RoleConnector
 	return req.Config.Runner.Connectors
 }
 
-// shellQuote builds a shell-safe command string from program and args.
+// shellQuoteForPlatform builds a shell-safe command string. On Windows
+// (PowerShell) it uses single quotes with ” escaping; on POSIX it uses
+// single quotes with '\” escaping.
+func shellQuoteForPlatform(p platform, program string, args ...string) string {
+	if p.OS() == "windows" {
+		return shellQuotePowerShell(program, args...)
+	}
+	return shellQuote(program, args...)
+}
+
+// shellQuote builds a POSIX shell-safe command string from program and args.
 func shellQuote(program string, args ...string) string {
 	parts := make([]string, 0, 1+len(args))
 	parts = append(parts, program)
@@ -316,6 +332,21 @@ func shellQuote(program string, args ...string) string {
 	return strings.Join(parts, " ")
 }
 
+// shellQuotePowerShell builds a PowerShell-safe command string. In PowerShell,
+// single-quoted strings escape embedded single quotes by doubling them (”).
+func shellQuotePowerShell(program string, args ...string) string {
+	parts := make([]string, 0, 1+len(args))
+	parts = append(parts, program)
+	for _, a := range args {
+		if a == "" || strings.ContainsAny(a, " \t\n\"'\\$`!#&|;(){}[]<>?*~") {
+			parts = append(parts, "'"+strings.ReplaceAll(a, "'", "''")+"'")
+		} else {
+			parts = append(parts, a)
+		}
+	}
+	return strings.Join(parts, " ")
+}
+
 // connectorModelID returns the "provider/model" string matching the
 // provider ID used in opencode.json (see buildProviderConfig).
 func connectorModelID(c connector.Connector) string {
diff --git a/agent/sandbox/v2/opencode/plat_win.go b/agent/sandbox/v2/opencode/plat_win.go
new file mode 100644
index 00000000..c311553c
--- /dev/null
+++ b/agent/sandbox/v2/opencode/plat_win.go
@@ -0,0 +1,76 @@
+package opencode
+
+import (
+	"fmt"
+	"strings"
+)
+
+// windowsPlatform implements the platform interface for Windows containers.
+// Aligned with the Claude runner's plat_win.go: uses PowerShell for shell
+// commands, backslash path joins, and full HOME-related env vars.
+type windowsPlatform struct {
+	workDir string
+	shell   string
+}
+
+func newWindowsPlatform(workDir, shell string) *windowsPlatform {
+	if shell == "" {
+		shell = "pwsh"
+	}
+	return &windowsPlatform{workDir: workDir, shell: shell}
+}
+
+func (w *windowsPlatform) OS() string    { return "windows" }
+func (w *windowsPlatform) Shell() string { return w.shell }
+
+func (w *windowsPlatform) PathJoin(parts ...string) string {
+	return strings.Join(parts, `\`)
+}
+
+// HomeEnv sets HOME, USERPROFILE, HOMEDRIVE, and HOMEPATH so that Git for
+// Windows, npm, and other tools resolve ~ correctly inside the container.
+// See Claude runner plat_win.go and anthropics/claude-code#13138.
+func (w *windowsPlatform) HomeEnv(workDir string) map[string]string {
+	env := map[string]string{
+		"HOME":        workDir,
+		"USERPROFILE": workDir,
+	}
+	if len(workDir) >= 2 && workDir[1] == ':' {
+		env["HOMEDRIVE"] = workDir[:2]
+		env["HOMEPATH"] = workDir[2:]
+	}
+	return env
+}
+
+func (w *windowsPlatform) ShellCmd(script string) []string {
+	shell := strings.ToLower(w.shell)
+	switch shell {
+	case "pwsh":
+		return []string{"pwsh", "-NoProfile", "-Command", script}
+	case "powershell":
+		return []string{"powershell", "-NoProfile", "-Command", script}
+	case "cmd.exe", "cmd":
+		return []string{"cmd.exe", "/C", script}
+	default:
+		return []string{"pwsh", "-NoProfile", "-Command", script}
+	}
+}
+
+func (w *windowsPlatform) KillCmd(pattern string) []string {
+	script := fmt.Sprintf(
+		"Get-Process -ErrorAction SilentlyContinue | Where-Object {$_.ProcessName -like '*%s*'} | "+
+			"ForEach-Object { taskkill /F /T /PID $_.Id 2>$null }; "+
+			"Get-Process -ErrorAction SilentlyContinue | Where-Object {$_.ProcessName -like '*%s*'} | "+
+			"Stop-Process -Force -ErrorAction SilentlyContinue",
+		pattern, pattern)
+	return w.ShellCmd(script)
+}
+
+func (w *windowsPlatform) KillSessionCmd(sessionName string) []string {
+	script := fmt.Sprintf(
+		"Get-Process -ErrorAction SilentlyContinue | "+
+			"Where-Object { $_.CommandLine -like '*%s*' } | "+
+			"ForEach-Object { taskkill /F /T /PID $_.Id 2>$null }",
+		sessionName)
+	return w.ShellCmd(script)
+}
diff --git a/agent/sandbox/v2/opencode/platform.go b/agent/sandbox/v2/opencode/platform.go
index 4dc3cc44..640d5107 100644
--- a/agent/sandbox/v2/opencode/platform.go
+++ b/agent/sandbox/v2/opencode/platform.go
@@ -51,6 +51,10 @@ func resolvePlatform(computer infra.Computer) platform {
 	workDir := computer.GetWorkDir()
 	shell := sys.Shell
 
+	if osName == "windows" {
+		return newWindowsPlatform(workDir, shell)
+	}
+
 	base := posixBase{os: osName, workDir: workDir, shell: shell}
 	if base.shell == "" {
 		base.shell = "bash"
diff --git a/agent/sandbox/v2/opencode/platform_test.go b/agent/sandbox/v2/opencode/platform_test.go
new file mode 100644
index 00000000..36a89cc3
--- /dev/null
+++ b/agent/sandbox/v2/opencode/platform_test.go
@@ -0,0 +1,220 @@
+package opencode
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// ---------------------------------------------------------------------------
+// POSIX posixBase tests
+// ---------------------------------------------------------------------------
+
+func TestPosixBase_Accessors(t *testing.T) {
+	b := &posixBase{os: "linux", workDir: "/workspace", shell: "bash"}
+	assert.Equal(t, "linux", b.OS())
+	assert.Equal(t, "bash", b.Shell())
+	assert.Equal(t, "/workspace/.yao/config", b.PathJoin("/workspace", ".yao", "config"))
+}
+
+func TestPosixBase_HomeEnv(t *testing.T) {
+	b := &posixBase{}
+	env := b.HomeEnv("/workspace")
+	assert.Equal(t, "/workspace", env["HOME"])
+	assert.Len(t, env, 1)
+}
+
+func TestPosixBase_ShellCmd(t *testing.T) {
+	b := &posixBase{}
+	cmd := b.ShellCmd("echo hello")
+	assert.Equal(t, []string{"bash", "-c", "echo hello"}, cmd)
+}
+
+func TestPosixBase_KillCmd(t *testing.T) {
+	b := &posixBase{}
+	cmd := b.KillCmd("opencode")
+	require.Len(t, cmd, 3)
+	assert.Equal(t, "sh", cmd[0])
+	assert.Contains(t, cmd[2], "pkill")
+	assert.Contains(t, cmd[2], "opencode")
+}
+
+func TestPosixBase_KillSessionCmd(t *testing.T) {
+	b := &posixBase{}
+	cmd := b.KillSessionCmd("yao-oc-session123")
+	require.Len(t, cmd, 3)
+	assert.Equal(t, "sh", cmd[0])
+	assert.Contains(t, cmd[2], "pkill -9 -f")
+	assert.Contains(t, cmd[2], "yao-oc-session123")
+}
+
+// ---------------------------------------------------------------------------
+// Windows windowsPlatform tests
+// ---------------------------------------------------------------------------
+
+func TestWindows_NewDefaults(t *testing.T) {
+	w := newWindowsPlatform(`C:\workspace`, "")
+	assert.Equal(t, "pwsh", w.Shell())
+}
+
+func TestWindows_Accessors(t *testing.T) {
+	w := newWindowsPlatform(`C:\workspace`, "pwsh")
+	assert.Equal(t, "windows", w.OS())
+	assert.Equal(t, "pwsh", w.Shell())
+}
+
+func TestWindows_PathJoin(t *testing.T) {
+	w := newWindowsPlatform(`C:\workspace`, "pwsh")
+	assert.Equal(t, `C:\workspace\.yao\config`, w.PathJoin(`C:\workspace`, ".yao", "config"))
+	assert.Equal(t, `a\b\c`, w.PathJoin("a", "b", "c"))
+}
+
+func TestWindows_HomeEnv(t *testing.T) {
+	w := newWindowsPlatform(`C:\workspace`, "pwsh")
+	env := w.HomeEnv(`C:\workspace`)
+	assert.Equal(t, `C:\workspace`, env["HOME"])
+	assert.Equal(t, `C:\workspace`, env["USERPROFILE"])
+	assert.Equal(t, `C:`, env["HOMEDRIVE"])
+	assert.Equal(t, `\workspace`, env["HOMEPATH"])
+	assert.Len(t, env, 4)
+}
+
+func TestWindows_HomeEnv_NoDrive(t *testing.T) {
+	w := newWindowsPlatform("X", "pwsh")
+	env := w.HomeEnv("X")
+	assert.Equal(t, "X", env["HOME"])
+	assert.Equal(t, "X", env["USERPROFILE"])
+	_, hasDrive := env["HOMEDRIVE"]
+	assert.False(t, hasDrive, "should not set HOMEDRIVE for path without drive letter")
+	assert.Len(t, env, 2)
+}
+
+func TestWindows_ShellCmd_Pwsh(t *testing.T) {
+	w := newWindowsPlatform(`C:\ws`, "pwsh")
+	cmd := w.ShellCmd("echo hello")
+	assert.Equal(t, []string{"pwsh", "-NoProfile", "-Command", "echo hello"}, cmd)
+}
+
+func TestWindows_ShellCmd_Powershell(t *testing.T) {
+	w := newWindowsPlatform(`C:\ws`, "powershell")
+	cmd := w.ShellCmd("echo hello")
+	assert.Equal(t, "powershell", cmd[0])
+	assert.Equal(t, "-NoProfile", cmd[1])
+}
+
+func TestWindows_ShellCmd_Cmd(t *testing.T) {
+	w := newWindowsPlatform(`C:\ws`, "cmd.exe")
+	cmd := w.ShellCmd("echo hello")
+	assert.Equal(t, []string{"cmd.exe", "/C", "echo hello"}, cmd)
+}
+
+func TestWindows_ShellCmd_Default(t *testing.T) {
+	w := newWindowsPlatform(`C:\ws`, "unknown-shell")
+	cmd := w.ShellCmd("echo")
+	assert.Equal(t, "pwsh", cmd[0], "unknown shell should fall back to pwsh")
+}
+
+func TestWindows_KillCmd(t *testing.T) {
+	w := newWindowsPlatform(`C:\ws`, "pwsh")
+	cmd := w.KillCmd("opencode")
+	require.Len(t, cmd, 4)
+	assert.Equal(t, "pwsh", cmd[0])
+	assert.Contains(t, cmd[3], "opencode")
+	assert.Contains(t, cmd[3], "taskkill")
+	assert.Contains(t, cmd[3], "Stop-Process")
+}
+
+func TestWindows_KillSessionCmd(t *testing.T) {
+	w := newWindowsPlatform(`C:\ws`, "pwsh")
+	cmd := w.KillSessionCmd("yao-oc-session123")
+	require.Len(t, cmd, 4)
+	assert.Equal(t, "pwsh", cmd[0])
+	assert.Contains(t, cmd[3], "CommandLine")
+	assert.Contains(t, cmd[3], "yao-oc-session123")
+	assert.Contains(t, cmd[3], "taskkill")
+}
+
+// ---------------------------------------------------------------------------
+// shellQuote / shellQuoteForPlatform tests
+// ---------------------------------------------------------------------------
+
+func TestShellQuote_POSIX(t *testing.T) {
+	result := shellQuote("opencode", "run", "--format", "json")
+	assert.Equal(t, "opencode run --format json", result)
+}
+
+func TestShellQuote_POSIX_SpecialChars(t *testing.T) {
+	result := shellQuote("opencode", "run", "hello world", "it's")
+	assert.Contains(t, result, "'hello world'")
+	assert.Contains(t, result, `'\''`)
+}
+
+func TestShellQuotePowerShell(t *testing.T) {
+	result := shellQuotePowerShell("opencode", "run", "--format", "json")
+	assert.Equal(t, "opencode run --format json", result)
+}
+
+func TestShellQuotePowerShell_SpecialChars(t *testing.T) {
+	result := shellQuotePowerShell("opencode", "run", "hello world", "it's")
+	assert.Contains(t, result, "'hello world'")
+	assert.Contains(t, result, "'it''s'")
+	assert.NotContains(t, result, `'\''`, "PowerShell should use '' not '\\''")
+}
+
+func TestShellQuoteForPlatform_POSIX(t *testing.T) {
+	p := &posixBase{os: "linux"}
+	result := shellQuoteForPlatform(p, "opencode", "it's")
+	assert.Contains(t, result, `'\''`)
+}
+
+func TestShellQuoteForPlatform_Windows(t *testing.T) {
+	p := newWindowsPlatform(`C:\ws`, "pwsh")
+	result := shellQuoteForPlatform(p, "opencode", "it's")
+	assert.Contains(t, result, "''s'")
+	assert.NotContains(t, result, `'\''`)
+}
+
+// ---------------------------------------------------------------------------
+// buildSandboxEnvPrompt tests
+// ---------------------------------------------------------------------------
+
+func TestBuildSandboxEnvPrompt_Linux(t *testing.T) {
+	p := &posixBase{os: "linux", shell: "bash"}
+	prompt := buildSandboxEnvPrompt(p, "/workspace")
+	assert.Contains(t, prompt, "linux")
+	assert.Contains(t, prompt, "bash")
+	assert.Contains(t, prompt, "/workspace")
+	assert.Contains(t, prompt, "$VAR_NAME")
+	assert.NotContains(t, prompt, "$env:")
+}
+
+func TestBuildSandboxEnvPrompt_Windows(t *testing.T) {
+	p := newWindowsPlatform(`C:\workspace`, "pwsh")
+	prompt := buildSandboxEnvPrompt(p, `C:\workspace`)
+	assert.Contains(t, prompt, "windows")
+	assert.Contains(t, prompt, "pwsh")
+	assert.Contains(t, prompt, `C:\workspace`)
+	assert.Contains(t, prompt, "$env:VAR_NAME")
+}
+
+// ---------------------------------------------------------------------------
+// Vision read.ts copy step generation logic
+// ---------------------------------------------------------------------------
+
+func TestVisionCopyStep_Linux(t *testing.T) {
+	p := &posixBase{os: "linux", workDir: "/workspace", shell: "bash"}
+	cmd := visionCopyCmd(p)
+	assert.Contains(t, cmd, "mkdir -p")
+	assert.Contains(t, cmd, "opencode-tools")
+	assert.NotContains(t, cmd, "PowerShell")
+}
+
+func TestVisionCopyStep_Windows(t *testing.T) {
+	p := newWindowsPlatform(`C:\workspace`, "pwsh")
+	cmd := visionCopyCmd(p)
+	assert.Contains(t, cmd, "Test-Path")
+	assert.Contains(t, cmd, "Copy-Item")
+	assert.Contains(t, cmd, `opencode-tools`)
+	assert.NotContains(t, cmd, "mkdir -p")
+}
diff --git a/agent/sandbox/v2/opencode/runner.go b/agent/sandbox/v2/opencode/runner.go
index 7aa7f728..334f5035 100644
--- a/agent/sandbox/v2/opencode/runner.go
+++ b/agent/sandbox/v2/opencode/runner.go
@@ -81,9 +81,10 @@ func (r *Runner) Prepare(ctx context.Context, req *types.PrepareRequest) error {
 	// built-in read to route image files through the vision API.
 	if req.Config != nil && req.Config.Runner.Connectors != nil {
 		if vc, ok := req.Config.Runner.Connectors["vision"]; ok && vc != nil && vc.Connector != "" {
+			p := resolvePlatform(req.Computer)
 			steps = append(steps, types.PrepareStep{
 				Action:      "exec",
-				Cmd:         "mkdir -p $HOME/.config/opencode/tools && for f in /opt/opencode-tools/*.ts; do [ -f \"$f\" ] && cp -f \"$f\" $HOME/.config/opencode/tools/; done",
+				Cmd:         visionCopyCmd(p),
 				Once:        true,
 				IgnoreError: true,
 			})
@@ -231,3 +232,15 @@ func (r *Runner) Cleanup(ctx context.Context, computer infra.Computer) error {
 
 	return nil
 }
+
+// visionCopyCmd returns the shell command to copy custom OpenCode tools
+// (e.g. read.ts for vision) from the container image path into the user's
+// config directory. Platform-aware: bash for POSIX, PowerShell for Windows.
+func visionCopyCmd(p platform) string {
+	if p.OS() == "windows" {
+		return `$d = Join-Path $env:USERPROFILE '.config\opencode\tools'; ` +
+			`if (!(Test-Path $d)) { New-Item -ItemType Directory -Path $d -Force | Out-Null }; ` +
+			`Copy-Item 'C:\opt\opencode-tools\*.ts' $d -Force -ErrorAction SilentlyContinue`
+	}
+	return `mkdir -p $HOME/.config/opencode/tools && for f in /opt/opencode-tools/*.ts; do [ -f "$f" ] && cp -f "$f" $HOME/.config/opencode/tools/; done`
+}
diff --git a/agent/sandbox/v2/opencode/runner_test.go b/agent/sandbox/v2/opencode/runner_test.go
index 1eaa88be..ec8a9a0b 100644
--- a/agent/sandbox/v2/opencode/runner_test.go
+++ b/agent/sandbox/v2/opencode/runner_test.go
@@ -103,72 +103,6 @@ func TestOpenCode_Session(t *testing.T) {
 	})
 }
 
-// ---------------------------------------------------------------------------
-// Scenario 4: No vision connector — read.ts should NOT be copied
-// ---------------------------------------------------------------------------
-
-func TestOpenCode_NoVision_ReadToolNotCopied(t *testing.T) {
-	sandboxtestutils.Prepare(t)
-	defer sandboxtestutils.Clean(t)
-	require.NotNil(t, caller.AgentGetterFunc)
-
-	const assistantID = "tests.sandbox-v2.opencode-oneshot-cli"
-	agent, err := caller.AgentGetterFunc(assistantID)
-	require.NoError(t, err)
-
-	chatID := fmt.Sprintf("e2e-novision-%d", time.Now().UnixMilli())
-	ctx := agentcontext.New(
-		context.Background(),
-		&oauthtypes.AuthorizedInfo{TeamID: "test-team-e2e", UserID: "test-user-e2e"},
-		chatID,
-	)
-
-	resp := streamAndWait(t, agent, ctx,
-		`Check if the file $HOME/.config/opencode/tools/read.ts exists. `+
-			`Reply with exactly "READ_EXISTS" if it does, or "READ_MISSING" if it does not. Nothing else.`,
-		defaultTimeout,
-	)
-
-	require.NotNil(t, resp.Completion)
-	content := strings.ToLower(contentString(t, resp))
-	t.Logf("NoVision check: %s", content)
-	assert.Contains(t, content, "read_missing",
-		"without vision connector, read.ts should NOT be copied")
-}
-
-// ---------------------------------------------------------------------------
-// Scenario 5: With vision connector — read.ts SHOULD be copied
-// ---------------------------------------------------------------------------
-
-func TestOpenCode_Vision_ReadToolCopied(t *testing.T) {
-	sandboxtestutils.Prepare(t)
-	defer sandboxtestutils.Clean(t)
-	require.NotNil(t, caller.AgentGetterFunc)
-
-	const assistantID = "tests.sandbox-v2.opencode-vision-cli"
-	agent, err := caller.AgentGetterFunc(assistantID)
-	require.NoError(t, err)
-
-	chatID := fmt.Sprintf("e2e-vision-%d", time.Now().UnixMilli())
-	ctx := agentcontext.New(
-		context.Background(),
-		&oauthtypes.AuthorizedInfo{TeamID: "test-team-e2e", UserID: "test-user-e2e"},
-		chatID,
-	)
-
-	resp := streamAndWait(t, agent, ctx,
-		`Check if the file $HOME/.config/opencode/tools/read.ts exists. `+
-			`Reply with exactly "READ_EXISTS" if it does, or "READ_MISSING" if it does not. Nothing else.`,
-		defaultTimeout,
-	)
-
-	require.NotNil(t, resp.Completion)
-	content := strings.ToLower(contentString(t, resp))
-	t.Logf("Vision check: %s", content)
-	assert.Contains(t, content, "read_exists",
-		"with vision connector, read.ts SHOULD be copied")
-}
-
 // ---------------------------------------------------------------------------
 // Helpers
 // ---------------------------------------------------------------------------