diff --git a/agent/agent.go b/agent/agent.go
index 132c4b200181f..bcf4e50cc8bc9 100644
--- a/agent/agent.go
+++ b/agent/agent.go
@@ -92,7 +92,6 @@ type Client interface {
 	ReportStats(ctx context.Context, log slog.Logger, statsChan <-chan *agentsdk.Stats, setInterval func(time.Duration)) (io.Closer, error)
 	PostLifecycle(ctx context.Context, state agentsdk.PostLifecycleRequest) error
 	PostAppHealth(ctx context.Context, req agentsdk.PostAppHealthsRequest) error
-	PostStartup(ctx context.Context, req agentsdk.PostStartupRequest) error
 	PostMetadata(ctx context.Context, req agentsdk.PostMetadataRequest) error
 	PatchLogs(ctx context.Context, req agentsdk.PatchLogs) error
 	RewriteDERPMap(derpMap *tailcfg.DERPMap)
@@ -737,13 +736,18 @@ func (a *agent) run(ctx context.Context) error {
 	if err != nil {
 		return xerrors.Errorf("expand directory: %w", err)
 	}
-	err = a.client.PostStartup(ctx, agentsdk.PostStartupRequest{
+	subsys, err := agentsdk.ProtoFromSubsystems(a.subsystems)
+	if err != nil {
+		a.logger.Critical(ctx, "failed to convert subsystems", slog.Error(err))
+		return xerrors.Errorf("failed to convert subsystems: %w", err)
+	}
+	_, err = aAPI.UpdateStartup(ctx, &proto.UpdateStartupRequest{Startup: &proto.Startup{
 		Version:           buildinfo.Version(),
 		ExpandedDirectory: manifest.Directory,
-		Subsystems:        a.subsystems,
-	})
+		Subsystems:        subsys,
+	}})
 	if err != nil {
-		return xerrors.Errorf("update workspace agent version: %w", err)
+		return xerrors.Errorf("update workspace agent startup: %w", err)
 	}
 
 	oldManifest := a.manifest.Swap(&manifest)
diff --git a/agent/agent_test.go b/agent/agent_test.go
index 9f9d7efbaa39f..f7cbe41e96ec0 100644
--- a/agent/agent_test.go
+++ b/agent/agent_test.go
@@ -1394,56 +1394,52 @@ func TestAgent_Startup(t *testing.T) {
 
 	t.Run("EmptyDirectory", func(t *testing.T) {
 		t.Parallel()
+		ctx := testutil.Context(t, testutil.WaitShort)
 
 		_, client, _, _, _ := setupAgent(t, agentsdk.Manifest{
 			Directory: "",
 		}, 0)
-		assert.Eventually(t, func() bool {
-			return client.GetStartup().Version != ""
-		}, testutil.WaitShort, testutil.IntervalFast)
-		require.Equal(t, "", client.GetStartup().ExpandedDirectory)
+		startup := testutil.RequireRecvCtx(ctx, t, client.GetStartup())
+		require.Equal(t, "", startup.GetExpandedDirectory())
 	})
 
 	t.Run("HomeDirectory", func(t *testing.T) {
 		t.Parallel()
+		ctx := testutil.Context(t, testutil.WaitShort)
 
 		_, client, _, _, _ := setupAgent(t, agentsdk.Manifest{
 			Directory: "~",
 		}, 0)
-		assert.Eventually(t, func() bool {
-			return client.GetStartup().Version != ""
-		}, testutil.WaitShort, testutil.IntervalFast)
+		startup := testutil.RequireRecvCtx(ctx, t, client.GetStartup())
 		homeDir, err := os.UserHomeDir()
 		require.NoError(t, err)
-		require.Equal(t, homeDir, client.GetStartup().ExpandedDirectory)
+		require.Equal(t, homeDir, startup.GetExpandedDirectory())
 	})
 
 	t.Run("NotAbsoluteDirectory", func(t *testing.T) {
 		t.Parallel()
+		ctx := testutil.Context(t, testutil.WaitShort)
 
 		_, client, _, _, _ := setupAgent(t, agentsdk.Manifest{
 			Directory: "coder/coder",
 		}, 0)
-		assert.Eventually(t, func() bool {
-			return client.GetStartup().Version != ""
-		}, testutil.WaitShort, testutil.IntervalFast)
+		startup := testutil.RequireRecvCtx(ctx, t, client.GetStartup())
 		homeDir, err := os.UserHomeDir()
 		require.NoError(t, err)
-		require.Equal(t, filepath.Join(homeDir, "coder/coder"), client.GetStartup().ExpandedDirectory)
+		require.Equal(t, filepath.Join(homeDir, "coder/coder"), startup.GetExpandedDirectory())
 	})
 
 	t.Run("HomeEnvironmentVariable", func(t *testing.T) {
 		t.Parallel()
+		ctx := testutil.Context(t, testutil.WaitShort)
 
 		_, client, _, _, _ := setupAgent(t, agentsdk.Manifest{
 			Directory: "$HOME",
 		}, 0)
-		assert.Eventually(t, func() bool {
-			return client.GetStartup().Version != ""
-		}, testutil.WaitShort, testutil.IntervalFast)
+		startup := testutil.RequireRecvCtx(ctx, t, client.GetStartup())
 		homeDir, err := os.UserHomeDir()
 		require.NoError(t, err)
-		require.Equal(t, homeDir, client.GetStartup().ExpandedDirectory)
+		require.Equal(t, homeDir, startup.GetExpandedDirectory())
 	})
 }
 
diff --git a/agent/agenttest/client.go b/agent/agenttest/client.go
index a1fcc8c44a52e..3f721a3135a55 100644
--- a/agent/agenttest/client.go
+++ b/agent/agenttest/client.go
@@ -88,7 +88,6 @@ type Client struct {
 
 	mu              sync.Mutex // Protects following.
 	lifecycleStates []codersdk.WorkspaceAgentLifecycle
-	startup         agentsdk.PostStartupRequest
 	logs            []agentsdk.Log
 	derpMapUpdates  chan *tailcfg.DERPMap
 	derpMapOnce     sync.Once
@@ -173,10 +172,8 @@ func (c *Client) PostAppHealth(ctx context.Context, req agentsdk.PostAppHealthsR
 	return nil
 }
 
-func (c *Client) GetStartup() agentsdk.PostStartupRequest {
-	c.mu.Lock()
-	defer c.mu.Unlock()
-	return c.startup
+func (c *Client) GetStartup() <-chan *agentproto.Startup {
+	return c.fakeAgentAPI.startupCh
 }
 
 func (c *Client) GetMetadata() map[string]agentsdk.Metadata {
@@ -198,14 +195,6 @@ func (c *Client) PostMetadata(ctx context.Context, req agentsdk.PostMetadataRequ
 	return nil
 }
 
-func (c *Client) PostStartup(ctx context.Context, startup agentsdk.PostStartupRequest) error {
-	c.mu.Lock()
-	defer c.mu.Unlock()
-	c.startup = startup
-	c.logger.Debug(ctx, "post startup", slog.F("req", startup))
-	return nil
-}
-
 func (c *Client) GetStartupLogs() []agentsdk.Log {
 	c.mu.Lock()
 	defer c.mu.Unlock()
@@ -250,7 +239,8 @@ type FakeAgentAPI struct {
 	t      testing.TB
 	logger slog.Logger
 
-	manifest *agentproto.Manifest
+	manifest  *agentproto.Manifest
+	startupCh chan *agentproto.Startup
 
 	getServiceBannerFunc func() (codersdk.ServiceBannerConfig, error)
 }
@@ -294,9 +284,9 @@ func (*FakeAgentAPI) BatchUpdateAppHealths(context.Context, *agentproto.BatchUpd
 	panic("implement me")
 }
 
-func (*FakeAgentAPI) UpdateStartup(context.Context, *agentproto.UpdateStartupRequest) (*agentproto.Startup, error) {
-	// TODO implement me
-	panic("implement me")
+func (f *FakeAgentAPI) UpdateStartup(_ context.Context, req *agentproto.UpdateStartupRequest) (*agentproto.Startup, error) {
+	f.startupCh <- req.GetStartup()
+	return req.GetStartup(), nil
 }
 
 func (*FakeAgentAPI) BatchUpdateMetadata(context.Context, *agentproto.BatchUpdateMetadataRequest) (*agentproto.BatchUpdateMetadataResponse, error) {
@@ -311,8 +301,9 @@ func (*FakeAgentAPI) BatchCreateLogs(context.Context, *agentproto.BatchCreateLog
 
 func NewFakeAgentAPI(t testing.TB, logger slog.Logger, manifest *agentproto.Manifest) *FakeAgentAPI {
 	return &FakeAgentAPI{
-		t:        t,
-		logger:   logger.Named("FakeAgentAPI"),
-		manifest: manifest,
+		t:         t,
+		logger:    logger.Named("FakeAgentAPI"),
+		manifest:  manifest,
+		startupCh: make(chan *agentproto.Startup, 100),
 	}
 }
diff --git a/coderd/agentapi/api.go b/coderd/agentapi/api.go
index e6db4736af5f3..73b50d9c0c446 100644
--- a/coderd/agentapi/api.go
+++ b/coderd/agentapi/api.go
@@ -29,8 +29,6 @@ import (
 	tailnetproto "github.com/coder/coder/v2/tailnet/proto"
 )
 
-const AgentAPIVersionDRPC = "2.0"
-
 // API implements the DRPC agent API interface from agent/proto. This struct is
 // instantiated once per agent connection and kept alive for the duration of the
 // session.
diff --git a/coderd/agentapi/lifecycle.go b/coderd/agentapi/lifecycle.go
index 662d0c0c2e28e..9c34b2c5485ad 100644
--- a/coderd/agentapi/lifecycle.go
+++ b/coderd/agentapi/lifecycle.go
@@ -6,6 +6,7 @@ import (
 	"time"
 
 	"github.com/google/uuid"
+	"golang.org/x/exp/slices"
 	"golang.org/x/mod/semver"
 	"golang.org/x/xerrors"
 	"google.golang.org/protobuf/types/known/timestamppb"
@@ -16,6 +17,12 @@ import (
 	"github.com/coder/coder/v2/coderd/database/dbtime"
 )
 
+type contextKeyAPIVersion struct{}
+
+func WithAPIVersion(ctx context.Context, version string) context.Context {
+	return context.WithValue(ctx, contextKeyAPIVersion{}, version)
+}
+
 type LifecycleAPI struct {
 	AgentFn                  func(context.Context) (database.WorkspaceAgent, error)
 	WorkspaceIDFn            func(context.Context, *database.WorkspaceAgent) (uuid.UUID, error)
@@ -123,6 +130,10 @@ func (a *LifecycleAPI) UpdateLifecycle(ctx context.Context, req *agentproto.Upda
 }
 
 func (a *LifecycleAPI) UpdateStartup(ctx context.Context, req *agentproto.UpdateStartupRequest) (*agentproto.Startup, error) {
+	apiVersion, ok := ctx.Value(contextKeyAPIVersion{}).(string)
+	if !ok {
+		return nil, xerrors.Errorf("internal error; api version unspecified")
+	}
 	workspaceAgent, err := a.AgentFn(ctx)
 	if err != nil {
 		return nil, err
@@ -164,13 +175,14 @@ func (a *LifecycleAPI) UpdateStartup(ctx context.Context, req *agentproto.Update
 			dbSubsystems = append(dbSubsystems, dbSubsystem)
 		}
 	}
+	slices.Sort(dbSubsystems)
 
 	err = a.Database.UpdateWorkspaceAgentStartupByID(ctx, database.UpdateWorkspaceAgentStartupByIDParams{
 		ID:                workspaceAgent.ID,
 		Version:           req.Startup.Version,
 		ExpandedDirectory: req.Startup.ExpandedDirectory,
 		Subsystems:        dbSubsystems,
-		APIVersion:        AgentAPIVersionDRPC,
+		APIVersion:        apiVersion,
 	})
 	if err != nil {
 		return nil, xerrors.Errorf("update workspace agent startup in database: %w", err)
diff --git a/coderd/agentapi/lifecycle_test.go b/coderd/agentapi/lifecycle_test.go
index 855ff9329acc9..3a88ee5cb3726 100644
--- a/coderd/agentapi/lifecycle_test.go
+++ b/coderd/agentapi/lifecycle_test.go
@@ -382,10 +382,11 @@ func TestUpdateStartup(t *testing.T) {
 				database.WorkspaceAgentSubsystemEnvbuilder,
 				database.WorkspaceAgentSubsystemExectrace,
 			},
-			APIVersion: agentapi.AgentAPIVersionDRPC,
+			APIVersion: "2.0",
 		}).Return(nil)
 
-		resp, err := api.UpdateStartup(context.Background(), &agentproto.UpdateStartupRequest{
+		ctx := agentapi.WithAPIVersion(context.Background(), "2.0")
+		resp, err := api.UpdateStartup(ctx, &agentproto.UpdateStartupRequest{
 			Startup: startup,
 		})
 		require.NoError(t, err)
@@ -416,7 +417,8 @@ func TestUpdateStartup(t *testing.T) {
 			Subsystems:        []agentproto.Startup_Subsystem{},
 		}
 
-		resp, err := api.UpdateStartup(context.Background(), &agentproto.UpdateStartupRequest{
+		ctx := agentapi.WithAPIVersion(context.Background(), "2.0")
+		resp, err := api.UpdateStartup(ctx, &agentproto.UpdateStartupRequest{
 			Startup: startup,
 		})
 		require.Error(t, err)
@@ -451,7 +453,8 @@ func TestUpdateStartup(t *testing.T) {
 			},
 		}
 
-		resp, err := api.UpdateStartup(context.Background(), &agentproto.UpdateStartupRequest{
+		ctx := agentapi.WithAPIVersion(context.Background(), "2.0")
+		resp, err := api.UpdateStartup(ctx, &agentproto.UpdateStartupRequest{
 			Startup: startup,
 		})
 		require.Error(t, err)
diff --git a/coderd/workspaceagents_test.go b/coderd/workspaceagents_test.go
index 53bece8addd4b..bf303dd0bf703 100644
--- a/coderd/workspaceagents_test.go
+++ b/coderd/workspaceagents_test.go
@@ -24,7 +24,6 @@ import (
 	"github.com/coder/coder/v2/agent"
 	"github.com/coder/coder/v2/agent/agenttest"
 	agentproto "github.com/coder/coder/v2/agent/proto"
-	"github.com/coder/coder/v2/coderd"
 	"github.com/coder/coder/v2/coderd/coderdtest"
 	"github.com/coder/coder/v2/coderd/coderdtest/oidctest"
 	"github.com/coder/coder/v2/coderd/database"
@@ -1389,13 +1388,13 @@ func TestWorkspaceAgent_Startup(t *testing.T) {
 			}
 		)
 
-		err := agentClient.PostStartup(ctx, agentsdk.PostStartupRequest{
+		err := postStartup(ctx, t, agentClient, &agentproto.Startup{
 			Version:           expectedVersion,
 			ExpandedDirectory: expectedDir,
-			Subsystems: []codersdk.AgentSubsystem{
+			Subsystems: []agentproto.Startup_Subsystem{
 				// Not sorted.
-				expectedSubsystems[1],
-				expectedSubsystems[0],
+				agentproto.Startup_EXECTRACE,
+				agentproto.Startup_ENVBOX,
 			},
 		})
 		require.NoError(t, err)
@@ -1409,7 +1408,7 @@ func TestWorkspaceAgent_Startup(t *testing.T) {
 		require.Equal(t, expectedDir, wsagent.ExpandedDirectory)
 		// Sorted
 		require.Equal(t, expectedSubsystems, wsagent.Subsystems)
-		require.Equal(t, coderd.AgentAPIVersionREST, wsagent.APIVersion)
+		require.Equal(t, agentproto.CurrentVersion.String(), wsagent.APIVersion)
 	})
 
 	t.Run("InvalidSemver", func(t *testing.T) {
@@ -1427,13 +1426,10 @@ func TestWorkspaceAgent_Startup(t *testing.T) {
 
 		ctx := testutil.Context(t, testutil.WaitMedium)
 
-		err := agentClient.PostStartup(ctx, agentsdk.PostStartupRequest{
+		err := postStartup(ctx, t, agentClient, &agentproto.Startup{
 			Version: "1.2.3",
 		})
-		require.Error(t, err)
-		cerr, ok := codersdk.AsError(err)
-		require.True(t, ok)
-		require.Equal(t, http.StatusBadRequest, cerr.StatusCode())
+		require.ErrorContains(t, err, "invalid agent semver version")
 	})
 }
 
@@ -1640,3 +1636,15 @@ func requireGetManifest(ctx context.Context, t testing.TB, client agent.Client)
 	require.NoError(t, err)
 	return manifest
 }
+
+func postStartup(ctx context.Context, t testing.TB, client agent.Client, startup *agentproto.Startup) error {
+	conn, err := client.Listen(ctx)
+	require.NoError(t, err)
+	defer func() {
+		cErr := conn.Close()
+		require.NoError(t, cErr)
+	}()
+	aAPI := agentproto.NewDRPCAgentClient(conn)
+	_, err = aAPI.UpdateStartup(ctx, &agentproto.UpdateStartupRequest{Startup: startup})
+	return err
+}
diff --git a/coderd/workspaceagentsrpc.go b/coderd/workspaceagentsrpc.go
index e5398b271570e..c59e50387f784 100644
--- a/coderd/workspaceagentsrpc.go
+++ b/coderd/workspaceagentsrpc.go
@@ -154,6 +154,7 @@ func (api *API) workspaceAgentRPC(rw http.ResponseWriter, r *http.Request) {
 		Auth: tailnet.AgentTunnelAuth{},
 	}
 	ctx = tailnet.WithStreamID(ctx, streamID)
+	ctx = agentapi.WithAPIVersion(ctx, version)
 	err = agentAPI.Serve(ctx, mux)
 	if err != nil {
 		api.Logger.Warn(ctx, "workspace agent RPC listen error", slog.Error(err))
diff --git a/codersdk/agentsdk/agentsdk.go b/codersdk/agentsdk/agentsdk.go
index ad1e6bbda880c..cc19dd88e3ca9 100644
--- a/codersdk/agentsdk/agentsdk.go
+++ b/codersdk/agentsdk/agentsdk.go
@@ -556,18 +556,6 @@ type PostStartupRequest struct {
 	Subsystems        []codersdk.AgentSubsystem `json:"subsystems"`
 }
 
-func (c *Client) PostStartup(ctx context.Context, req PostStartupRequest) error {
-	res, err := c.SDK.Request(ctx, http.MethodPost, "/api/v2/workspaceagents/me/startup", req)
-	if err != nil {
-		return err
-	}
-	defer res.Body.Close()
-	if res.StatusCode != http.StatusOK {
-		return codersdk.ReadBodyAsError(res)
-	}
-	return nil
-}
-
 type Log struct {
 	CreatedAt time.Time         `json:"created_at"`
 	Output    string            `json:"output"`
diff --git a/codersdk/agentsdk/convert.go b/codersdk/agentsdk/convert.go
index 2a20cf5d0c98c..1838e52b013d9 100644
--- a/codersdk/agentsdk/convert.go
+++ b/codersdk/agentsdk/convert.go
@@ -266,3 +266,15 @@ func ProtoFromServiceBanner(sb codersdk.ServiceBannerConfig) *proto.ServiceBanne
 		BackgroundColor: sb.BackgroundColor,
 	}
 }
+
+func ProtoFromSubsystems(ss []codersdk.AgentSubsystem) ([]proto.Startup_Subsystem, error) {
+	ret := make([]proto.Startup_Subsystem, len(ss))
+	for i, s := range ss {
+		pi, ok := proto.Startup_Subsystem_value[strings.ToUpper(string(s))]
+		if !ok {
+			return nil, xerrors.Errorf("unknown subsystem: %s", s)
+		}
+		ret[i] = proto.Startup_Subsystem(pi)
+	}
+	return ret, nil
+}
diff --git a/codersdk/agentsdk/convert_test.go b/codersdk/agentsdk/convert_test.go
index 9205777e13a28..3417416b43fe1 100644
--- a/codersdk/agentsdk/convert_test.go
+++ b/codersdk/agentsdk/convert_test.go
@@ -8,6 +8,7 @@ import (
 	"github.com/stretchr/testify/require"
 	"tailscale.com/tailcfg"
 
+	"github.com/coder/coder/v2/agent/proto"
 	"github.com/coder/coder/v2/codersdk"
 	"github.com/coder/coder/v2/codersdk/agentsdk"
 	"github.com/coder/coder/v2/tailnet"
@@ -144,3 +145,19 @@ func TestManifest(t *testing.T) {
 	require.Equal(t, manifest.Metadata, back.Metadata)
 	require.Equal(t, manifest.Scripts, back.Scripts)
 }
+
+func TestSubsystems(t *testing.T) {
+	t.Parallel()
+	ss := []codersdk.AgentSubsystem{
+		codersdk.AgentSubsystemEnvbox,
+		codersdk.AgentSubsystemEnvbuilder,
+		codersdk.AgentSubsystemExectrace,
+	}
+	ps, err := agentsdk.ProtoFromSubsystems(ss)
+	require.NoError(t, err)
+	require.Equal(t, ps, []proto.Startup_Subsystem{
+		proto.Startup_ENVBOX,
+		proto.Startup_ENVBUILDER,
+		proto.Startup_EXECTRACE,
+	})
+}