diff --git a/THIRD_PARTY_LICENSES.md b/THIRD_PARTY_LICENSES.md
index 6190cd4076..b5fef46da7 100644
--- a/THIRD_PARTY_LICENSES.md
+++ b/THIRD_PARTY_LICENSES.md
@@ -125,7 +125,7 @@ To regenerate this file after changing dependencies, run `task cli:licenses`.
 | [github.com/devsy-org/agentapi](https://github.com/devsy-org/agentapi) | `v1.0.1` | MPL-2.0 |
 | [github.com/devsy-org/api](https://github.com/devsy-org/api) | `v1.1.0` | MPL-2.0 |
 | [github.com/devsy-org/apiserver](https://github.com/devsy-org/apiserver) | `v1.5.4` | Apache-2.0 |
-| [github.com/devsy-org/devsy-runtime-sdk](https://github.com/devsy-org/devsy-runtime-sdk) | `v1.2.0` | MPL-2.0 |
+| [github.com/devsy-org/devsy-runtime-sdk](https://github.com/devsy-org/devsy-runtime-sdk) | `v1.4.0` | MPL-2.0 |
 | [github.com/devsy-org/ssh](https://github.com/devsy-org/ssh) | `v1.2.9` | BSD-3-Clause |
 | [github.com/distribution/reference](https://github.com/distribution/reference) | `v0.6.0` | Apache-2.0 |
 | [github.com/docker/cli](https://github.com/docker/cli) | `v29.8.0+incompatible` | Apache-2.0 |
@@ -379,7 +379,7 @@ To regenerate this file after changing dependencies, run `task cli:licenses`.
 | [k8s.io/metrics](https://github.com/kubernetes/metrics) | `v0.37.0` | Apache-2.0 |
 | [k8s.io/streaming](https://github.com/kubernetes/streaming) | `v0.37.1` | Apache-2.0 |
 | [k8s.io/utils](https://github.com/kubernetes/utils) | `v0.0.0-20260707023825-cf1189d6abe3` | Apache-2.0 |
-| [mvdan.cc/sh/v3](https://mvdan.cc/sh/v3) | `v3.14.0` | BSD-3-Clause |
+| [mvdan.cc/sh/v3](https://mvdan.cc/sh/v3) | `v3.14.1` | BSD-3-Clause |
 | [sigs.k8s.io/apiserver-network-proxy/konnectivity-client](https://sigs.k8s.io/apiserver-network-proxy/konnectivity-client) | `v0.36.0` | Apache-2.0 |
 | [sigs.k8s.io/controller-runtime](https://sigs.k8s.io/controller-runtime) | `v0.25.0` | Apache-2.0 |
 | [sigs.k8s.io/json](https://sigs.k8s.io/json) | `v0.0.0-20250730193827-2d320260d730` | Apache-2.0 |
diff --git a/go.mod b/go.mod
index 60d2f53716..5cb904f858 100644
--- a/go.mod
+++ b/go.mod
@@ -23,7 +23,7 @@ require (
 	github.com/devsy-org/agentapi v1.0.1
 	github.com/devsy-org/api v1.1.0
 	github.com/devsy-org/apiserver v1.5.4
-	github.com/devsy-org/devsy-runtime-sdk v1.2.0
+	github.com/devsy-org/devsy-runtime-sdk v1.4.0
 	github.com/devsy-org/ssh v1.2.9
 	github.com/distribution/reference v0.6.0
 	github.com/docker/cli v29.8.0+incompatible
diff --git a/go.sum b/go.sum
index 8974774707..678ef9b1dd 100644
--- a/go.sum
+++ b/go.sum
@@ -416,8 +416,8 @@ github.com/devsy-org/api v1.1.0 h1:l7T9k7RVwatwN4lxeDTF3iN6EYmfGZgR3ZTJMDGha1M=
 github.com/devsy-org/api v1.1.0/go.mod h1:mAZklKdnywJYiXDReBLte/H+3m69z6G7RHB3n1lI53Q=
 github.com/devsy-org/apiserver v1.5.4 h1:/bEPrSRSlfii2QHxc9qAiXlQawNJfIaPLraR3bYKHxg=
 github.com/devsy-org/apiserver v1.5.4/go.mod h1:sDFCTjCN13wAHhno4KX0Z756gCI8ttW/c7NwTzo16K0=
-github.com/devsy-org/devsy-runtime-sdk v1.2.0 h1:yQ6yJq00ZOcdn0+IjYygK7Byk9qLBuZgSD1AIiA/FRo=
-github.com/devsy-org/devsy-runtime-sdk v1.2.0/go.mod h1:MiBP/fiY83DAS0TueEiJZSHYZ1vq85UR4KJTMfHIM+E=
+github.com/devsy-org/devsy-runtime-sdk v1.4.0 h1:dJqPJrKxJVmgWT9r1vnZ08rqZTxshyazj9eM+fZG8k4=
+github.com/devsy-org/devsy-runtime-sdk v1.4.0/go.mod h1:MiBP/fiY83DAS0TueEiJZSHYZ1vq85UR4KJTMfHIM+E=
 github.com/devsy-org/ssh v1.2.9 h1:KHqX1xAplGFanm0FMSAojtiC9nV/UFxUeP/5jU5quak=
 github.com/devsy-org/ssh v1.2.9/go.mod h1:Uff10+cSSDZk3bG07u5D9+eQ8GMGqsgE70WCUJWcHv4=
 github.com/devsy-org/tailscale v1.102.2 h1:9SB6htvO+HmG8alal8WGCshHapfHR7dUFRSMYiFIzIM=
diff --git a/pkg/driver/external/internal/testfixture/main.go b/pkg/driver/external/internal/testfixture/main.go
index aa8ce9cda1..c020889662 100644
--- a/pkg/driver/external/internal/testfixture/main.go
+++ b/pkg/driver/external/internal/testfixture/main.go
@@ -48,7 +48,8 @@ func serve(mode, state string, delay time.Duration) {
 	}
 	fixtureMode := mode
 	if fixtureMode == "blocked" || fixtureMode == "environment" || fixtureMode == "block-info" ||
-		fixtureMode == "env-error" || strings.HasPrefix(fixtureMode, "stream-") {
+		fixtureMode == "env-error" || fixtureMode == "workspace-identity" ||
+		strings.HasPrefix(fixtureMode, "stream-") {
 		fixtureMode = fake.Normal
 	}
 	runtime, err := fake.New(fake.Config{StateDir: state, Mode: fixtureMode})
@@ -122,6 +123,12 @@ func (f *fixture) RunImage(
 	ctx context.Context,
 	request *runtimev1.RunImageRequest,
 ) (*runtimev1.RunImageResponse, error) {
+	if f.mode == "workspace-identity" {
+		request.Labels = append(request.Labels,
+			"fixture.remote-user="+request.GetRemoteUser(),
+			"fixture.dockerless="+strconv.FormatBool(request.GetDockerless()),
+		)
+	}
 	if f.mode == "stream-workspace-secret" {
 		if err := f.saveEnvironment(request); err != nil {
 			return nil, err
diff --git a/pkg/driver/external/run_image.go b/pkg/driver/external/run_image.go
index d9657fdf79..73ddcdc733 100644
--- a/pkg/driver/external/run_image.go
+++ b/pkg/driver/external/run_image.go
@@ -53,6 +53,8 @@ func runImageRequest(
 		Image:             options.Image,
 		ImageBuiltLocally: options.ImageBuilt,
 		User:              options.User,
+		RemoteUser:        options.RemoteUser,
+		Dockerless:        options.Dockerless,
 		Entrypoint:        options.Entrypoint,
 		Args:              slices.Clone(options.Cmd),
 		Environment:       maps.Clone(options.Env),
diff --git a/pkg/driver/external/run_image_test.go b/pkg/driver/external/run_image_test.go
index 2ff4ca2900..134e340058 100644
--- a/pkg/driver/external/run_image_test.go
+++ b/pkg/driver/external/run_image_test.go
@@ -35,8 +35,9 @@ func (s *ImageRunSuite) TestResolvedIntentAndOwnership() {
 			UID:        "host-uid",
 			Image:      imageRunImage,
 			ImageBuilt: true,
-			User:       "root",
-			RemoteUser: "developer",
+			User:       fixtureProcessUser,
+			RemoteUser: fixtureRemoteUser,
+			Dockerless: true,
 			Entrypoint: imageRunEntrypoint,
 			Cmd:        []string{"", "literal $arg"},
 			Env:        map[string]string{"TOKEN": "secret"},
@@ -83,7 +84,9 @@ func (s *ImageRunSuite) TestResolvedIntentAndOwnership() {
 		WorkspaceId:       fixtureWorkspace,
 		Image:             imageRunImage,
 		ImageBuiltLocally: true,
-		User:              "root",
+		User:              fixtureProcessUser,
+		RemoteUser:        fixtureRemoteUser,
+		Dockerless:        true,
 		Entrypoint:        imageRunEntrypoint,
 		Args:              []string{"", "literal $arg"},
 		Environment: map[string]string{
diff --git a/pkg/driver/external/workspace_identity_test.go b/pkg/driver/external/workspace_identity_test.go
new file mode 100644
index 0000000000..1f9af2c05d
--- /dev/null
+++ b/pkg/driver/external/workspace_identity_test.go
@@ -0,0 +1,48 @@
+package external
+
+import (
+	"context"
+	"strconv"
+	"time"
+
+	"github.com/devsy-org/devsy/pkg/driver"
+)
+
+const (
+	fixtureProcessUser = "root"
+	fixtureRemoteUser  = "developer"
+)
+
+func (s *HostSuite) TestWorkspaceIdentityThroughRuntimeProcess() {
+	for _, tc := range []struct {
+		name       string
+		user       string
+		remoteUser string
+		dockerless bool
+	}{
+		{"dockerless developer", fixtureProcessUser, fixtureRemoteUser, true},
+		{"prebuilt developer", fixtureProcessUser, fixtureRemoteUser, false},
+		{"numeric developer", fixtureProcessUser, "1000:1001", true},
+		{"empty developer identity", fixtureProcessUser, "", false},
+		{"unset identities", "", "", false},
+	} {
+		s.Run(tc.name, func() {
+			host := s.host("workspace-identity")
+			ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+			defer cancel()
+			s.Require().NoError(host.RunImageDevContainer(ctx, &driver.RunImageDevContainerParams{
+				WorkspaceID: fixtureWorkspace,
+				Options: &driver.RunOptions{
+					Image: fixtureImage, User: tc.user,
+					RemoteUser: tc.remoteUser, Dockerless: tc.dockerless,
+				},
+			}))
+			found, err := host.FindDevContainer(ctx, fixtureWorkspace)
+			s.Require().NoError(err)
+			s.Require().NotNil(found)
+			s.Equal(tc.user, found.Config.User)
+			s.Equal(tc.remoteUser, found.Config.Labels["fixture.remote-user"])
+			s.Equal(strconv.FormatBool(tc.dockerless), found.Config.Labels["fixture.dockerless"])
+		})
+	}
+}
diff --git a/sites/docs-devsy-sh/content/docs/developing-providers/runtime-protocol.mdx b/sites/docs-devsy-sh/content/docs/developing-providers/runtime-protocol.mdx
index f8c1b46c28..2075055581 100644
--- a/sites/docs-devsy-sh/content/docs/developing-providers/runtime-protocol.mdx
+++ b/sites/docs-devsy-sh/content/docs/developing-providers/runtime-protocol.mdx
@@ -7,7 +7,7 @@ description: Contract for external runtime driver authors using the Devsy Runtim
 Providers can select `agent.driver: external` using the [external runtime configuration](./driver). The SDK and Devsy host integration are available; backend extraction and parity testing remain in development.
 </Callout>
 
-The canonical [protobuf schema](https://github.com/devsy-org/devsy-runtime-sdk/blob/main/proto/devsy/runtime/v1/runtime.proto) is maintained in the [Devsy Runtime SDK](https://github.com/devsy-org/devsy-runtime-sdk). The module path is `github.com/devsy-org/devsy-runtime-sdk`; the logical plugin name is `devsy-runtime`. HashiCorp application protocol 1 and Info API major 1/minor 0 are separate version checks. Same-major newer minor versions are accepted. Unknown mount/recreate enum values are rejected because they control host behavior.
+The canonical [protobuf schema](https://github.com/devsy-org/devsy-runtime-sdk/blob/main/proto/devsy/runtime/v1/runtime.proto) is maintained in the [Devsy Runtime SDK](https://github.com/devsy-org/devsy-runtime-sdk). The module path is `github.com/devsy-org/devsy-runtime-sdk`; the logical plugin name is `devsy-runtime`. HashiCorp application protocol 1 and Info API major 1/minor 1 are separate version checks. Same-major newer minor versions are accepted. Unknown mount/recreate enum values are rejected because they control host behavior.
 
 ## Runtime boundary
 
@@ -15,6 +15,8 @@ Info, Preflight, ProvisioningPreflight, Find, TargetArchitecture, RunImage, Star
 
 RunImage receives resolved intent. Its empty response acknowledges completion; Find queries state. `image_built_locally` is an image-origin hint, not permission to build. Optional privileged/init flags distinguish absent from explicit false. Environment and mounts may contain secrets and must not appear in diagnostic logs.
 
+`remote_user` carries the developer identity used for workspace ownership, separately from the container process `user`. The host forwards both values without substituting one for the other. Runtimes use `remote_user` when set, otherwise `user`, otherwise `root` for workspace ownership. `dockerless` indicates that the host will build the developer filesystem after the image starts, so that identity may not yet exist in the image. A runtime that resolves mount ownership from image contents must validate this case before changing workspace resources. These fields describe provisioning intent and do not authorize replacement of an existing workspace.
+
 Runtime name, driver name/version, and capabilities are required in Info. Runtime version may be empty when a backend cannot report it without expensive setup. An empty mount list means no supported mount types. ProvisioningPreflight may be a no-op when its capability is false. Logs may return Unimplemented when its capability is false. Reprovision means RunImage can update an existing workspace with complete resolved intent; it does not imply that an empty request is safe. The Devsy host does not enable in-place reprovisioning; workspace changes follow the negotiated stop/delete recreate policy.
 
 TargetArchitecture returns canonical `amd64` or `arm64`. A runtime may require an existing workspace to answer; hosts must not require pre-start architecture discovery from such runtimes.