diff --git a/PROGRESS.md b/PROGRESS.md
index 0922015..1507f54 100644
--- a/PROGRESS.md
+++ b/PROGRESS.md
@@ -70,7 +70,7 @@ satisfied phases; `--json` matches the spec contract; `down` decrements refs;
 - [x] X2 `internal/health` full DAG — **DONE** (PR #37: BuildGraph/Cycle/Waves/RequireHealthchecks)
 - [~] X3 hooks full — **PARTIAL**: workspace + project preUp/postUp wired into the saga (PR #46). Remaining: firstRun/postPull (need provision scope_key) + --skip-hooks/--force-hooks flags.
 - [x] X4 profiles/selective-up — **DONE** (PR #53: internal/profile.Resolve — Q-PROFILE resolved). Saga --profile wiring is X5.
-- [ ] X5 orchestrate completion — TODO  *(ready: X2,X3,X4 in; wire profile slicing + DAG-pruned health into the saga)*
+- [x] X5 orchestrate completion — **DONE** (PR #55: `up --profile` service-slicing wired into BuildUp — inactive projects drop out, compose-up restricted to active services, shared phase + health gate pruned to `active.Shared`). Follow-ups (small): spec-native `COMPOSE_PROFILES`/`profiles:` emission, `memoryBudgetMB` warning.
 - [x] X6 `internal/doctor` full matrix + `--fix` — **DONE** (trust/dns/shared probes PRs #33/#35/#48 + safe reconcile `--fix` PR #49)
 - [ ] X7 `workspace destroy`/`uninstall` — BLOCKED (S5,X6)
 - [x] X8 self-update notifier — **DONE** (PR #25, `28c4a78`)
diff --git a/internal/cli/destroy.go b/internal/cli/destroy.go
new file mode 100644
index 0000000..e3f120e
--- /dev/null
+++ b/internal/cli/destroy.go
@@ -0,0 +1,178 @@
+package cli
+
+import (
+	"bufio"
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/spf13/cobra"
+
+	"github.com/open-source-cloud/devstack/internal/docker"
+	"github.com/open-source-cloud/devstack/internal/generate"
+	"github.com/open-source-cloud/devstack/internal/lock"
+	"github.com/open-source-cloud/devstack/internal/orchestrate"
+)
+
+// newWorkspaceCmd wires `devstack workspace <sub>` — workspace-scoped lifecycle
+// (spec 13 teardown). Today it carries `destroy`; `uninstall` (machine-global
+// teardown incl. CA removal) is a separate top-level verb.
+func newWorkspaceCmd(g *GlobalOpts) *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "workspace",
+		Short: "Workspace-level lifecycle (teardown)",
+	}
+	cmd.AddCommand(newWorkspaceDestroyCmd(g))
+	return cmd
+}
+
+// newWorkspaceDestroyCmd wires `devstack workspace destroy` (spec 13): tear down
+// THIS workspace's project stacks, release its ref/port ledger rows, warm-stop
+// any shared service left at zero refs, and remove generated `.devstack/`
+// artifacts. It leaves machine-global state (the shared network, the CA, alias
+// symlinks) intact for other workspaces, and — by design in this first cut —
+// PRESERVES data: named volumes and provisioned DBs/roles survive (shared
+// per-service volume removal is `uninstall`/`db gc` territory).
+func newWorkspaceDestroyCmd(g *GlobalOpts) *cobra.Command {
+	var yes bool
+	cmd := &cobra.Command{
+		Use:   "destroy",
+		Short: "Tear down THIS workspace's stacks and release its refs/ports (volumes/DBs preserved)",
+		Long: "destroy reverses what `up` created for this workspace: it `compose down`s every\n" +
+			"project stack, drops the workspace's ref + port ledger rows (under the lock),\n" +
+			"warm-stops any shared service now at zero references, and removes the generated\n" +
+			"`.devstack/` artifacts.\n\n" +
+			"It is data-preserving: named volumes and provisioned databases SURVIVE, and the\n" +
+			"shared network / local CA / alias symlinks are left for other workspaces. Full\n" +
+			"data + machine-global removal is `uninstall`.",
+		Args: cobra.NoArgs,
+		RunE: func(cmd *cobra.Command, _ []string) error {
+			// Fail fast before touching Docker: a scripted (--json) run can't answer
+			// an interactive prompt, so it must pass --yes explicitly.
+			if g.JSON && !yes {
+				return fmt.Errorf("refusing to destroy without confirmation: pass --yes for --json/non-interactive use")
+			}
+
+			d, closeFn, err := buildUpDeps(cmd)
+			if err != nil {
+				return err
+			}
+			defer closeFn()
+
+			projects := sortedProjectNames(d.Model)
+			if !yes {
+				prompt := fmt.Sprintf(
+					"This tears down workspace %q (%d project stack(s)) and releases its refs/ports.\n"+
+						"Volumes and databases are PRESERVED. Type 'yes' to continue: ",
+					d.Model.Workspace.Name, len(projects))
+				if !confirm(cmd, prompt) {
+					fmt.Fprintln(cmd.OutOrStdout(), "aborted")
+					return nil
+				}
+			}
+
+			res := destroyWorkspace(cmd.Context(), d, projects)
+			if g.JSON {
+				if err := writeJSON(cmd, res); err != nil {
+					return err
+				}
+			} else {
+				w := cmd.OutOrStdout()
+				for _, p := range res.Projects {
+					fmt.Fprintf(w, "[ok]      down %s\n", p)
+				}
+				for _, s := range res.SharedStopped {
+					fmt.Fprintf(w, "[ok]      stopped shared %s (0 refs)\n", s)
+				}
+				for _, e := range res.Errors {
+					fmt.Fprintf(w, "[warn]    %s\n", e)
+				}
+				fmt.Fprintf(w, "destroyed workspace %q: %d stack(s) down, %d shared stopped (volumes/DBs preserved)\n",
+					d.Model.Workspace.Name, len(res.Projects), len(res.SharedStopped))
+			}
+			if len(res.Errors) > 0 {
+				return fmt.Errorf("destroy completed with %d error(s)", len(res.Errors))
+			}
+			return nil
+		},
+	}
+	cmd.Flags().BoolVar(&yes, "yes", false, "skip the confirmation prompt (required for --json/non-interactive)")
+	return cmd
+}
+
+// DestroyResult is the machine-readable outcome of `workspace destroy`.
+type DestroyResult struct {
+	Workspace     string   `json:"workspace"`
+	Projects      []string `json:"projects"`       // project stacks brought down
+	SharedStopped []string `json:"shared_stopped"` // orphaned shared services warm-stopped
+	Errors        []string `json:"errors,omitempty"`
+}
+
+// destroyWorkspace performs the teardown mechanics (no prompting) so it is
+// unit-testable with injected mocks. It is best-effort: a failure on one project
+// is recorded and the rest proceed, so a partially-broken workspace can still be
+// cleaned up.
+func destroyWorkspace(ctx context.Context, d orchestrate.UpDeps, projects []string) DestroyResult {
+	res := DestroyResult{Workspace: d.Model.Workspace.Name}
+	runner := d.Runner
+	if runner == nil {
+		runner = docker.ExecRunner{}
+	}
+
+	// 1. compose down each project stack (containers + project default network;
+	// named volumes survive — never -v here).
+	for _, p := range projects {
+		outDir := filepath.Join(d.Model.ProjectDir(p), generate.GenDir)
+		composeFile := filepath.Join(outDir, generate.ComposeFile)
+		if _, err := os.Stat(composeFile); err != nil {
+			composeFile = "" // label-driven `compose -p devstack-<p> down`
+		}
+		cp := docker.Compose{Project: "devstack-" + p, File: composeFile, Dir: outDir, Runner: runner}
+		if err := cp.Down(ctx, false); err != nil {
+			res.Errors = append(res.Errors, fmt.Sprintf("down %s: %v", p, err))
+			continue
+		}
+		res.Projects = append(res.Projects, p)
+	}
+
+	// 2. drop this workspace's ledger rows (refs + ports) under the flock.
+	if err := lock.WithLock(ctx, d.LockPath, func() error {
+		for _, p := range projects {
+			if _, err := d.DB.RemoveProjectRefs(p); err != nil {
+				return err
+			}
+			if err := d.DB.ReleasePortsFor(p); err != nil {
+				return err
+			}
+		}
+		return nil
+	}); err != nil {
+		res.Errors = append(res.Errors, fmt.Sprintf("ledger cleanup: %v", err))
+	}
+
+	// 3. warm-stop any shared service now at zero refs (reversible; volumes
+	// survive). GC enumerates by ledger ∩ live labels, so it only touches
+	// services no OTHER workspace references.
+	if gc, err := d.Manager.GC(ctx, true); err != nil {
+		res.Errors = append(res.Errors, fmt.Sprintf("shared gc: %v", err))
+	} else {
+		res.SharedStopped = gc.Stopped
+	}
+
+	// 4. remove generated artifacts (.devstack): the workspace-root shared dir and
+	// each project's dir. Best-effort — a missing dir is fine.
+	_ = os.RemoveAll(filepath.Join(d.Model.Root, generate.GenDir))
+	for _, p := range projects {
+		_ = os.RemoveAll(filepath.Join(d.Model.ProjectDir(p), generate.GenDir))
+	}
+	return res
+}
+
+// confirm prompts on stdout and returns true only if the user types "yes".
+func confirm(cmd *cobra.Command, prompt string) bool {
+	fmt.Fprint(cmd.OutOrStdout(), prompt)
+	line, _ := bufio.NewReader(cmd.InOrStdin()).ReadString('\n')
+	return strings.EqualFold(strings.TrimSpace(line), "yes")
+}
diff --git a/internal/cli/destroy_test.go b/internal/cli/destroy_test.go
new file mode 100644
index 0000000..6ff6a71
--- /dev/null
+++ b/internal/cli/destroy_test.go
@@ -0,0 +1,169 @@
+package cli
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/open-source-cloud/devstack/internal/config"
+	"github.com/open-source-cloud/devstack/internal/docker"
+	"github.com/open-source-cloud/devstack/internal/generate"
+	"github.com/open-source-cloud/devstack/internal/orchestrate"
+	"github.com/open-source-cloud/devstack/internal/state"
+	"github.com/open-source-cloud/devstack/internal/template"
+	"github.com/open-source-cloud/devstack/internal/workspace"
+	"github.com/open-source-cloud/devstack/templates"
+)
+
+// destroyFakeRunner records compose invocations so teardown can assert on them.
+type destroyFakeRunner struct{ cmds [][]string }
+
+func (f *destroyFakeRunner) Run(_ context.Context, _ []string, _, name string, args ...string) error {
+	f.cmds = append(f.cmds, append([]string{name}, args...))
+	return nil
+}
+func (f *destroyFakeRunner) Output(_ context.Context, _ []string, _, name string, args ...string) ([]byte, error) {
+	f.cmds = append(f.cmds, append([]string{name}, args...))
+	return nil, nil
+}
+func (f *destroyFakeRunner) saw(needles ...string) bool {
+	for _, c := range f.cmds {
+		joined := strings.Join(c, " ")
+		all := true
+		for _, n := range needles {
+			if !strings.Contains(joined, n) {
+				all = false
+				break
+			}
+		}
+		if all {
+			return true
+		}
+	}
+	return false
+}
+
+// destroyFixture builds a one-project workspace whose shared postgres is live and
+// referenced by the project, with a generated .devstack/ on disk.
+func destroyFixture(t *testing.T) (orchestrate.UpDeps, *destroyFakeRunner) {
+	t.Helper()
+	root := t.TempDir()
+	write := func(rel, body string) {
+		p := filepath.Join(root, rel)
+		if err := os.MkdirAll(filepath.Dir(p), 0o755); err != nil {
+			t.Fatal(err)
+		}
+		if err := os.WriteFile(p, []byte(body), 0o644); err != nil {
+			t.Fatal(err)
+		}
+	}
+	write("workspace.yaml", "apiVersion: devstack/v1\nkind: Workspace\nname: demo\nshared:\n  postgres: { template: postgres, params: { version: \"16\" } }\nprojects:\n  - { name: app, path: app }\n")
+	write("app/devstack.yaml", "apiVersion: devstack/v1\nkind: Project\nname: app\nservices:\n  web:\n    template: node.vite\n    uses: [workspace.shared.postgres]\n")
+	// Generated artifacts that destroy must remove.
+	write(filepath.Join("app", generate.GenDir, generate.ComposeFile), "services: {}\n")
+	write(filepath.Join(generate.GenDir, "shared", generate.ComposeFile), "services: {}\n")
+
+	m, err := config.LoadAt(root)
+	if err != nil {
+		t.Fatalf("load: %v", err)
+	}
+	db, err := state.Open(context.Background(), filepath.Join(root, "state"), "ctx")
+	if err != nil {
+		t.Fatalf("state: %v", err)
+	}
+	t.Cleanup(func() { db.Close() })
+
+	mc := &docker.MockClient{
+		Context: "ctx",
+		Containers: []docker.Container{{
+			ID: "pg1", Name: "devstack-shared-postgres-1", State: "running",
+			Labels: map[string]string{generate.LabelManaged: "true", generate.LabelShared: "postgres"},
+		}},
+	}
+	src := template.NewFSSource(templates.FS)
+	lockPath := filepath.Join(root, "lock")
+	fr := &destroyFakeRunner{}
+	mgr := &workspace.Manager{Model: m, DB: db, Docker: mc, Source: src, LockPath: lockPath, Runner: fr}
+	d := orchestrate.UpDeps{
+		Model: m, DB: db, Docker: mc, Manager: mgr, Source: src, LockPath: lockPath, Runner: fr,
+	}
+	return d, fr
+}
+
+func TestWorkspaceDestroyRegistered(t *testing.T) {
+	root := NewRootCmd(Options{})
+	c, _, err := root.Find([]string{"workspace", "destroy"})
+	if err != nil || c.Name() != "destroy" || c.RunE == nil {
+		t.Fatalf("workspace destroy not registered as a real command: %v", err)
+	}
+}
+
+func TestWorkspaceDestroyJSONRequiresYes(t *testing.T) {
+	t.Chdir(t.TempDir())
+	var out strings.Builder
+	root := NewRootCmd(Options{})
+	root.SetArgs([]string{"workspace", "destroy", "--json"})
+	root.SetOut(&out)
+	root.SetErr(&out)
+	// The --json-without-yes guard fires before any Docker/workspace access.
+	if err := root.Execute(); err == nil {
+		t.Fatal("workspace destroy --json without --yes must error")
+	}
+}
+
+func TestDestroyWorkspaceTeardown(t *testing.T) {
+	d, fr := destroyFixture(t)
+	ctx := context.Background()
+
+	// Seed live state: a ref row for the project + a port allocation it owns.
+	if err := d.Manager.RegisterUp(ctx, "app"); err != nil {
+		t.Fatalf("register up: %v", err)
+	}
+	if _, err := d.DB.AllocatePort("app", "web", 30000, 30100, func(int) bool { return true }); err != nil {
+		t.Fatalf("alloc port: %v", err)
+	}
+	if n, _ := d.DB.RefCount("shared-postgres"); n != 1 {
+		t.Fatalf("precondition: ref count = %d, want 1", n)
+	}
+
+	res := destroyWorkspace(ctx, d, []string{"app"})
+	if len(res.Errors) != 0 {
+		t.Fatalf("destroy errors: %v", res.Errors)
+	}
+
+	// Project stack was composed down (never with --volumes).
+	if !fr.saw("-p devstack-app", "down") {
+		t.Errorf("project stack was not composed down: %v", fr.cmds)
+	}
+	if fr.saw("down", "--volumes") {
+		t.Error("destroy must never pass --volumes (data preservation)")
+	}
+	// Project is in the result.
+	if len(res.Projects) != 1 || res.Projects[0] != "app" {
+		t.Errorf("projects = %v, want [app]", res.Projects)
+	}
+	// Ref rows + port rows for the project are gone.
+	if n, _ := d.DB.RefCount("shared-postgres"); n != 0 {
+		t.Errorf("ref count after destroy = %d, want 0", n)
+	}
+	if _, ok, _ := d.DB.PortFor("app", "web"); ok {
+		t.Error("port allocation for app/web should be released")
+	}
+	// The now-orphaned shared service was warm-stopped (compose stop on the shared
+	// stack), not downed.
+	if !fr.saw("-p "+generate.SharedStackName, "stop") {
+		t.Errorf("orphaned shared service was not warm-stopped: %v", fr.cmds)
+	}
+	if len(res.SharedStopped) != 1 || res.SharedStopped[0] != generate.SharedAlias("postgres") {
+		t.Errorf("shared stopped = %v, want [%s]", res.SharedStopped, generate.SharedAlias("postgres"))
+	}
+	// Generated artifacts were removed.
+	if _, err := os.Stat(filepath.Join(d.Model.Root, generate.GenDir)); !os.IsNotExist(err) {
+		t.Error("workspace .devstack/ should be removed")
+	}
+	if _, err := os.Stat(filepath.Join(d.Model.ProjectDir("app"), generate.GenDir)); !os.IsNotExist(err) {
+		t.Error("project .devstack/ should be removed")
+	}
+}
diff --git a/internal/cli/root.go b/internal/cli/root.go
index aea45d7..45cc6fe 100644
--- a/internal/cli/root.go
+++ b/internal/cli/root.go
@@ -90,6 +90,7 @@ func NewRootCmd(opts Options) *cobra.Command {
 		newTemplateCmd(g),
 		newSharedCmd(g),
 		newWsCmd(g),
+		newWorkspaceCmd(g),
 		newSelfCmd(g),
 		newStoreCmd(g),
 		newAliasCmd(g),
diff --git a/internal/cli/stubs.go b/internal/cli/stubs.go
index 2667c50..b4360cb 100644
--- a/internal/cli/stubs.go
+++ b/internal/cli/stubs.go
@@ -33,8 +33,5 @@ func addStubCommands(root *cobra.Command, _ *GlobalOpts) {
 		stub("shell", "Open a shell in a service container", "M2"),
 		stub("logs", "Stream service logs", "M2"),
 		stub("import", "Import an old devdock project.yaml into workspace.yaml + devstack.yaml", "M1"),
-		stub("workspace", "Workspace-level lifecycle", "M6",
-			stub("destroy", "Reverse ALL machine-global artifacts for this workspace", "M6"),
-		),
 	)
 }