diff --git a/generic_manager.go b/generic_manager.go
index 5303d9e..0ef61b2 100644
--- a/generic_manager.go
+++ b/generic_manager.go
@@ -32,43 +32,51 @@ func (m *GenericManager) Warnings() []string {
 	return m.warnings
 }
 
-func (m *GenericManager) Init(ctx context.Context) (*Result, error) {
-	input := CommandInput{
-		Args:  map[string]string{},
-		Flags: map[string]any{},
-	}
-
-	cmd, err := m.translator.BuildCommand(m.def.Name, "init", input)
+// run builds the command chain for an operation (base command plus any
+// then: entries) and executes them in order. It returns the first
+// command's result with subsequent results attached in Then. Execution
+// stops after the first non-zero exit; Success() on the returned result
+// reflects the whole chain.
+func (m *GenericManager) run(ctx context.Context, operation string, input CommandInput) (*Result, error) {
+	cmds, err := m.translator.BuildCommands(m.def.Name, operation, input)
 	if err != nil {
 		return nil, err
 	}
+	var first *Result
+	for i, cmd := range cmds {
+		res, err := m.runner.Run(ctx, m.dir, cmd...)
+		if i == 0 {
+			first = res
+		} else if first != nil && res != nil {
+			first.Then = append(first.Then, res)
+		}
+		if err != nil {
+			return first, err
+		}
+		if res == nil || res.ExitCode != 0 {
+			return first, nil
+		}
+	}
+	return first, nil
+}
 
-	return m.runner.Run(ctx, m.dir, cmd...)
+func (m *GenericManager) Init(ctx context.Context) (*Result, error) {
+	return m.run(ctx, "init", CommandInput{})
 }
 
 func (m *GenericManager) Install(ctx context.Context, opts InstallOptions) (*Result, error) {
-	input := CommandInput{
-		Args: map[string]string{},
+	return m.run(ctx, "install", CommandInput{
 		Flags: map[string]any{
 			"frozen":     opts.Frozen,
 			"clean":      opts.Clean,
 			"production": opts.Production,
 		},
-	}
-
-	cmd, err := m.translator.BuildCommand(m.def.Name, "install", input)
-	if err != nil {
-		return nil, err
-	}
-
-	return m.runner.Run(ctx, m.dir, cmd...)
+	})
 }
 
 func (m *GenericManager) Add(ctx context.Context, pkg string, opts AddOptions) (*Result, error) {
 	input := CommandInput{
-		Args: map[string]string{
-			argPackage: pkg,
-		},
+		Args: map[string]string{argPackage: pkg},
 		Flags: map[string]any{
 			"dev":       opts.Dev,
 			"optional":  opts.Optional,
@@ -76,79 +84,30 @@ func (m *GenericManager) Add(ctx context.Context, pkg string, opts AddOptions) (
 			"workspace": opts.Workspace,
 		},
 	}
-
 	if opts.Version != "" {
 		input.Args["version"] = opts.Version
 	}
-
-	cmd, err := m.translator.BuildCommand(m.def.Name, "add", input)
-	if err != nil {
-		return nil, err
-	}
-
-	return m.runner.Run(ctx, m.dir, cmd...)
+	return m.run(ctx, "add", input)
 }
 
 func (m *GenericManager) Remove(ctx context.Context, pkg string) (*Result, error) {
-	input := CommandInput{
-		Args: map[string]string{
-			argPackage: pkg,
-		},
-		Flags: map[string]any{},
-	}
-
-	cmd, err := m.translator.BuildCommand(m.def.Name, "remove", input)
-	if err != nil {
-		return nil, err
-	}
-
-	return m.runner.Run(ctx, m.dir, cmd...)
+	return m.run(ctx, "remove", CommandInput{Args: map[string]string{argPackage: pkg}})
 }
 
 func (m *GenericManager) List(ctx context.Context) (*Result, error) {
-	input := CommandInput{
-		Args:  map[string]string{},
-		Flags: map[string]any{},
-	}
-
-	cmd, err := m.translator.BuildCommand(m.def.Name, "list", input)
-	if err != nil {
-		return nil, err
-	}
-
-	return m.runner.Run(ctx, m.dir, cmd...)
+	return m.run(ctx, "list", CommandInput{})
 }
 
 func (m *GenericManager) Outdated(ctx context.Context) (*Result, error) {
-	input := CommandInput{
-		Args:  map[string]string{},
-		Flags: map[string]any{},
-	}
-
-	cmd, err := m.translator.BuildCommand(m.def.Name, "outdated", input)
-	if err != nil {
-		return nil, err
-	}
-
-	return m.runner.Run(ctx, m.dir, cmd...)
+	return m.run(ctx, "outdated", CommandInput{})
 }
 
 func (m *GenericManager) Update(ctx context.Context, pkg string) (*Result, error) {
-	input := CommandInput{
-		Args:  map[string]string{},
-		Flags: map[string]any{},
-	}
-
+	input := CommandInput{}
 	if pkg != "" {
-		input.Args[argPackage] = pkg
+		input.Args = map[string]string{argPackage: pkg}
 	}
-
-	cmd, err := m.translator.BuildCommand(m.def.Name, "update", input)
-	if err != nil {
-		return nil, err
-	}
-
-	return m.runner.Run(ctx, m.dir, cmd...)
+	return m.run(ctx, "update", input)
 }
 
 func (m *GenericManager) Supports(cap Capability) bool {
@@ -172,31 +131,11 @@ func (m *GenericManager) Capabilities() []Capability {
 }
 
 func (m *GenericManager) Vendor(ctx context.Context) (*Result, error) {
-	input := CommandInput{
-		Args:  map[string]string{},
-		Flags: map[string]any{},
-	}
-
-	cmd, err := m.translator.BuildCommand(m.def.Name, "vendor", input)
-	if err != nil {
-		return nil, err
-	}
-
-	return m.runner.Run(ctx, m.dir, cmd...)
+	return m.run(ctx, "vendor", CommandInput{})
 }
 
 func (m *GenericManager) Resolve(ctx context.Context) (*Result, error) {
-	input := CommandInput{
-		Args:  map[string]string{},
-		Flags: map[string]any{},
-	}
-
-	cmd, err := m.translator.BuildCommand(m.def.Name, "resolve", input)
-	if err != nil {
-		return nil, err
-	}
-
-	return m.runner.Run(ctx, m.dir, cmd...)
+	return m.run(ctx, "resolve", CommandInput{})
 }
 
 func (m *GenericManager) Path(ctx context.Context, pkg string) (*PathResult, error) {
diff --git a/generic_manager_test.go b/generic_manager_test.go
index e5b5241..1639697 100644
--- a/generic_manager_test.go
+++ b/generic_manager_test.go
@@ -61,6 +61,151 @@ func TestGenericManager_Add_CargoVersion(t *testing.T) {
 	}
 }
 
+func TestGenericManager_Add_RunsThenChain(t *testing.T) {
+	runner := NewMockRunner()
+	mgr := newTestManager(embeddedDef(t, "gomod"), runner)
+	res, err := mgr.Add(context.Background(), "github.com/pkg/errors", AddOptions{})
+	if err != nil {
+		t.Fatalf("Add: %v", err)
+	}
+	if len(runner.Captured) != 2 {
+		t.Fatalf("captured %d commands, want 2 (go get + go mod tidy)", len(runner.Captured))
+	}
+	if !slicesEqual(runner.Captured[0], []string{"go", "get", "github.com/pkg/errors"}) {
+		t.Errorf("cmd[0] = %v", runner.Captured[0])
+	}
+	if !slicesEqual(runner.Captured[1], []string{"go", "mod", "tidy"}) {
+		t.Errorf("cmd[1] = %v", runner.Captured[1])
+	}
+	if !slicesEqual(res.Command, runner.Captured[0]) {
+		t.Errorf("res.Command = %v, want the primary go get", res.Command)
+	}
+	if len(res.Then) != 1 || !slicesEqual(res.Then[0].Command, runner.Captured[1]) {
+		t.Errorf("res.Then = %+v, want the go mod tidy result", res.Then)
+	}
+	if !res.Success() {
+		t.Error("Success() should be true when all chain commands exit zero")
+	}
+}
+
+func TestGenericManager_Add_ChainNilFollowupError(t *testing.T) {
+	// A Runner that returns (nil, err) for the second call, as
+	// PolicyRunner does on a policy violation.
+	runner := NewMockRunner()
+	runner.Results = []*Result{{Command: []string{"go", "get", "x"}, ExitCode: 0}}
+	runner.Errors = []error{nil, errors.New("policy denied")}
+	mgr := newTestManager(embeddedDef(t, "gomod"), runner)
+	res, err := mgr.Add(context.Background(), "example.com/x", AddOptions{})
+	if err == nil {
+		t.Fatal("expected error from follow-up")
+	}
+	if res == nil {
+		t.Fatal("expected first command's result")
+	}
+	for _, th := range res.Then {
+		if th == nil {
+			t.Fatal("Then must not contain nil entries")
+		}
+	}
+	// Success() must not panic; its value is not asserted since the
+	// failure is signalled via the returned error, not the Result.
+	_ = res.Success()
+}
+
+func TestGenericManager_Add_ChainStopsOnFailure(t *testing.T) {
+	runner := NewMockRunner()
+	runner.Results = []*Result{
+		{Command: []string{"go", "get", "x"}, ExitCode: 1, Stderr: "boom"},
+	}
+	mgr := newTestManager(embeddedDef(t, "gomod"), runner)
+	res, err := mgr.Add(context.Background(), "example.com/x", AddOptions{})
+	if err != nil {
+		t.Fatalf("Add: %v", err)
+	}
+	if res.Success() {
+		t.Error("Success() should be false when first command exits non-zero")
+	}
+	if len(runner.Captured) != 1 {
+		t.Errorf("captured %d commands, want 1 (chain should stop)", len(runner.Captured))
+	}
+}
+
+func TestGenericManager_Add_ChainThenFails(t *testing.T) {
+	runner := NewMockRunner()
+	runner.Results = []*Result{
+		{Command: []string{"go", "get", "x"}, ExitCode: 0},
+		{Command: []string{"go", "mod", "tidy"}, ExitCode: 1, Stderr: "tidy failed"},
+	}
+	mgr := newTestManager(embeddedDef(t, "gomod"), runner)
+	res, err := mgr.Add(context.Background(), "example.com/x", AddOptions{})
+	if err != nil {
+		t.Fatalf("Add: %v", err)
+	}
+	if res.Success() {
+		t.Error("Success() should be false when a then: command exits non-zero")
+	}
+	if !slicesEqual(res.Command, []string{"go", "get", "x"}) {
+		t.Errorf("res.Command = %v, want the primary command", res.Command)
+	}
+	if len(res.Then) != 1 {
+		t.Fatalf("res.Then = %d, want 1", len(res.Then))
+	}
+	if res.Then[0].ExitCode != 1 || res.Then[0].Stderr != "tidy failed" {
+		t.Errorf("res.Then[0] = %+v", res.Then[0])
+	}
+}
+
+func TestGenericManager_Replace_RunsChain(t *testing.T) {
+	runner := NewMockRunner()
+	mgr := newTestManager(embeddedDef(t, "gomod"), runner)
+	res, err := mgr.Replace(context.Background(), "example.com/x", ReplaceOptions{Path: "../x"})
+	if err != nil {
+		t.Fatalf("Replace: %v", err)
+	}
+	// gomod Replace runs `go mod edit -replace ...` then `go mod tidy`
+	// as two separate operations; both must be reachable via Then.
+	if len(runner.Captured) != 2 {
+		t.Fatalf("captured %d commands, want 2", len(runner.Captured))
+	}
+	if !slicesEqual(runner.Captured[1], []string{"go", "mod", "tidy"}) {
+		t.Errorf("cmd[1] = %v, want go mod tidy", runner.Captured[1])
+	}
+	if len(res.Then) != 1 || !slicesEqual(res.Then[0].Command, runner.Captured[1]) {
+		t.Errorf("res.Then = %+v, want the tidy result", res.Then)
+	}
+}
+
+func TestGenericManager_Replace_RunsOperationThen(t *testing.T) {
+	// A synthetic definition where the replace operation itself has a
+	// then: entry, to prove Replace routes through the chain executor.
+	def := &definitions.Definition{
+		Name:   "gomod",
+		Binary: "go",
+		Commands: map[string]definitions.Command{
+			"replace": {
+				Base: []string{"mod", "edit"},
+				Args: map[string]definitions.Arg{"spec": {Flag: "-replace"}},
+				Then: []definitions.Command{{Base: []string{"post"}}},
+			},
+			"tidy": {Base: []string{"mod", "tidy"}},
+		},
+		Capabilities: []string{"replace_path"},
+	}
+	runner := NewMockRunner()
+	mgr := newTestManager(def, runner)
+	_, err := mgr.Replace(context.Background(), "example.com/x", ReplaceOptions{Path: "../x"})
+	if err != nil {
+		t.Fatalf("Replace: %v", err)
+	}
+	// replace + its then: (post) + tidy = 3
+	if len(runner.Captured) != 3 {
+		t.Fatalf("captured %d commands, want 3: %v", len(runner.Captured), runner.Captured)
+	}
+	if !slicesEqual(runner.Captured[1], []string{"go", "post"}) {
+		t.Errorf("then: command not run: %v", runner.Captured)
+	}
+}
+
 func TestGenericManager_Path_Raw(t *testing.T) {
 	def := &definitions.Definition{
 		Name:   "testpkg",
diff --git a/manager.go b/manager.go
index 6bf78e6..b46dc61 100644
--- a/manager.go
+++ b/manager.go
@@ -58,10 +58,24 @@ type Result struct {
 	Duration time.Duration
 	Cwd      string
 	Context  ExecContext
+	// Then holds the results of any follow-up commands the operation
+	// ran after this one, in order. It is empty for single-command
+	// operations and when this command failed.
+	Then []*Result
 }
 
+// Success reports whether this command and every follow-up in Then
+// exited zero.
 func (r *Result) Success() bool {
-	return r.ExitCode == 0
+	if r.ExitCode != 0 {
+		return false
+	}
+	for _, t := range r.Then {
+		if !t.Success() {
+			return false
+		}
+	}
+	return true
 }
 
 type PathResult struct {
diff --git a/replace.go b/replace.go
index 2356fc6..c199974 100644
--- a/replace.go
+++ b/replace.go
@@ -95,21 +95,22 @@ func (m *GenericManager) Replace(ctx context.Context, pkg string, opts ReplaceOp
 		return nil, err
 	}
 
-	var result *Result
+	var first *Result
 	for _, in := range inputs {
-		cmd, err := m.translator.BuildCommand(m.def.Name, in.operation, in.input)
-		if err != nil {
-			return nil, err
+		res, err := m.run(ctx, in.operation, in.input)
+		if first == nil {
+			first = res
+		} else if res != nil {
+			first.Then = append(first.Then, res)
 		}
-		result, err = m.runner.Run(ctx, m.dir, cmd...)
 		if err != nil {
-			return result, err
+			return first, err
 		}
-		if result.ExitCode != 0 {
-			return result, nil
+		if res != nil && !res.Success() {
+			return first, nil
 		}
 	}
-	return result, nil
+	return first, nil
 }
 
 type replaceInput struct {