fixup: address PR #267 review (backend abstraction + version helper dedup)

Addresses two structural issues from ako's review:

1. **sdk/mpr import in cmd_microflows_builder.go** — lookupMicroflowReturnType
   called mpr.ParseMicroflowBSON directly, violating the executor's backend
   abstraction contract. Added ParseMicroflowBSON(contents, unitID, containerID)
   to the MicroflowBackend interface, implemented on MprBackend (delegates to
   mpr.ParseMicroflowBSON) and Mock (Func-field with descriptive
   'MockBackend.ParseMicroflowBSON not configured' default). lookupMicroflow
   ReturnType now goes through fb.backend.ParseMicroflowBSON. sdk/mpr import
   removed from the builder.

2. **newestVersionedPath duplication** — the four version-comparison helpers
   (newestVersionedPath, versionFromPath, parseVersionParts, compareVersion
   Parts) lived identically in cmd/mxcli/docker/download.go and
   mdl/executor/roundtrip_helpers_test.go. Exported the production helper as
   docker.NewestVersionedPath (with a full doc comment explaining the
   ranking); internal docker callers updated; the integration-test harness
   now imports docker and calls docker.NewestVersionedPath. All four copies
   removed from the test file.

Author: hjothamendix

cmd/mxcli/docker/check.go

@@ -162,7 +162,7 @@ func ResolveMxForVersion(mxbuildPath, preferredVersion string) (string, error) {
 		if exact := exactVersionedPath(matches, preferredVersion); exact != "" {
 			return exact, nil
 		}
-		if newest := newestVersionedPath(matches); newest != "" {
+		if newest := NewestVersionedPath(matches); newest != "" {
 			return newest, nil
 		}
 	}

cmd/mxcli/docker/detect.go

@@ -116,7 +116,7 @@ func resolveMxBuild(explicitPath string, preferredVersion ...string) (string, er
 		if exact := exactVersionedPath(matches, targetVersion); exact != "" {
 			return exact, nil
 		}
-		if newest := newestVersionedPath(matches); newest != "" {
+		if newest := NewestVersionedPath(matches); newest != "" {
 			return newest, nil
 		}
 	}

cmd/mxcli/docker/download.go

@@ -76,7 +76,7 @@ func anyCachedBinaryPath(names []string) string {
 		found, _ := filepath.Glob(pattern)
 		matches = append(matches, found...)
 	}
-	return newestVersionedPath(matches)
+	return NewestVersionedPath(matches)
 }
 
 func globVersionedMatches(patterns []string) []string {
@@ -98,10 +98,16 @@ func exactVersionedPath(paths []string, version string) string {
 			exact = append(exact, path)
 		}
 	}
-	return newestVersionedPath(exact)
+	return NewestVersionedPath(exact)
 }
 
-func newestVersionedPath(paths []string) string {
+// NewestVersionedPath selects the lexicographically-highest "versioned"
+// directory from paths, where "versioned" means the grandparent directory
+// name parses as a dotted numeric version (`11.9.0`). Paths whose version
+// cannot be parsed compare as a pure lexicographic fallback, but always rank
+// below any parseable version. Used by both the mx-binary resolver and the
+// integration test harness.
+func NewestVersionedPath(paths []string) string {
 	var best string
 	var bestVersion []int
 	bestValid := false

mdl/backend/microflow.go

@@ -20,6 +20,12 @@ type MicroflowBackend interface {
 	// map. Used by diff-local and other callers that have raw map data.
 	ParseMicroflowFromRaw(raw map[string]any, unitID, containerID model.ID) *microflows.Microflow
 
+	// ParseMicroflowBSON parses raw microflow BSON bytes into a Microflow.
+	// Used by the executor to inspect microflows it has not necessarily
+	// loaded via ListMicroflows (e.g. to resolve a CALL MICROFLOW's return
+	// type from its raw unit).
+	ParseMicroflowBSON(contents []byte, unitID, containerID model.ID) (*microflows.Microflow, error)
+
 	ListNanoflows() ([]*microflows.Nanoflow, error)
 	GetNanoflow(id model.ID) (*microflows.Nanoflow, error)
 	CreateNanoflow(nf *microflows.Nanoflow) error

mdl/backend/mock/backend.go

@@ -82,6 +82,7 @@ type MockBackend struct {
 	DeleteMicroflowFunc       func(id model.ID) error
 	MoveMicroflowFunc         func(mf *microflows.Microflow) error
 	ParseMicroflowFromRawFunc func(raw map[string]any, unitID, containerID model.ID) *microflows.Microflow
+	ParseMicroflowBSONFunc    func(contents []byte, unitID, containerID model.ID) (*microflows.Microflow, error)
 	ListNanoflowsFunc         func() ([]*microflows.Nanoflow, error)
 	GetNanoflowFunc           func(id model.ID) (*microflows.Nanoflow, error)
 	CreateNanoflowFunc        func(nf *microflows.Nanoflow) error

mdl/backend/mock/mock_microflow.go

@@ -3,6 +3,8 @@
 package mock
 
 import (
+	"fmt"
+
 	"github.com/mendixlabs/mxcli/model"
 	"github.com/mendixlabs/mxcli/sdk/microflows"
 )
@@ -56,6 +58,13 @@ func (m *MockBackend) ParseMicroflowFromRaw(raw map[string]any, unitID, containe
 	panic("mock ParseMicroflowFromRaw called but ParseMicroflowFromRawFunc is not set")
 }
 
+func (m *MockBackend) ParseMicroflowBSON(contents []byte, unitID, containerID model.ID) (*microflows.Microflow, error) {
+	if m.ParseMicroflowBSONFunc != nil {
+		return m.ParseMicroflowBSONFunc(contents, unitID, containerID)
+	}
+	return nil, fmt.Errorf("MockBackend.ParseMicroflowBSON not configured")
+}
+
 func (m *MockBackend) ListNanoflows() ([]*microflows.Nanoflow, error) {
 	if m.ListNanoflowsFunc != nil {
 		return m.ListNanoflowsFunc()

mdl/backend/mpr/backend.go

@@ -231,6 +231,9 @@ func (b *MprBackend) ListNanoflows() ([]*microflows.Nanoflow, error) {
 func (b *MprBackend) ParseMicroflowFromRaw(raw map[string]any, unitID, containerID model.ID) *microflows.Microflow {
 	return mpr.ParseMicroflowFromRaw(raw, unitID, containerID)
 }
+func (b *MprBackend) ParseMicroflowBSON(contents []byte, unitID, containerID model.ID) (*microflows.Microflow, error) {
+	return mpr.ParseMicroflowBSON(contents, unitID, containerID)
+}
 func (b *MprBackend) GetNanoflow(id model.ID) (*microflows.Nanoflow, error) {
 	return b.reader.GetNanoflow(id)
 }

mdl/executor/cmd_microflows_builder.go

@@ -12,7 +12,6 @@ import (
 	"github.com/mendixlabs/mxcli/mdl/types"
 	"github.com/mendixlabs/mxcli/model"
 	"github.com/mendixlabs/mxcli/sdk/microflows"
-	"github.com/mendixlabs/mxcli/sdk/mpr"
 )
 
 // flowBuilder helps construct the flow graph from AST statements.
@@ -131,7 +130,7 @@ func (fb *flowBuilder) lookupMicroflowReturnType(qualifiedName string) microflow
 	}
 
 	if rawUnit, err := fb.backend.GetRawUnitByName("microflow", qualifiedName); err == nil && rawUnit != nil && len(rawUnit.Contents) > 0 {
-		if mf, err := mpr.ParseMicroflowBSON(rawUnit.Contents, model.ID(rawUnit.ID), ""); err == nil && mf != nil {
+		if mf, err := fb.backend.ParseMicroflowBSON(rawUnit.Contents, model.ID(rawUnit.ID), ""); err == nil && mf != nil {
 			return mf.ReturnType
 		}
 	}

mdl/executor/roundtrip_helpers_mx_test.go

@@ -8,6 +8,8 @@ import (
 	"os"
 	"path/filepath"
 	"testing"
+
+	"github.com/mendixlabs/mxcli/cmd/mxcli/docker"
 )
 
 func TestNewestVersionedPath_PicksNewestNumericVersion(t *testing.T) {
@@ -19,10 +21,10 @@ func TestNewestVersionedPath_PicksNewestNumericVersion(t *testing.T) {
 		"/tmp/.mxcli/mxbuild/9.24.40.80973/modeler/mx",
 	}
 
-	got := newestVersionedPath(paths)
+	got := docker.NewestVersionedPath(paths)
 	want := "/tmp/.mxcli/mxbuild/11.9.0/modeler/mx"
 	if got != want {
-		t.Fatalf("newestVersionedPath() = %q, want %q", got, want)
+		t.Fatalf("docker.NewestVersionedPath() = %q, want %q", got, want)
 	}
 }
 

mdl/executor/roundtrip_helpers_test.go

@@ -18,10 +18,10 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
-	"strconv"
 	"strings"
 	"testing"
 
+	"github.com/mendixlabs/mxcli/cmd/mxcli/docker"
 	"github.com/mendixlabs/mxcli/mdl/ast"
 	"github.com/mendixlabs/mxcli/mdl/backend"
 	mprbackend "github.com/mendixlabs/mxcli/mdl/backend/mpr"
@@ -160,88 +160,17 @@ func findMxBinary() string {
 	if home, err := os.UserHomeDir(); err == nil {
 		pattern := filepath.Join(home, ".mxcli", "mxbuild", "*", "modeler", "mx")
 		if matches, _ := filepath.Glob(pattern); len(matches) > 0 {
-			return newestVersionedPath(matches)
+			return docker.NewestVersionedPath(matches)
 		}
 	}
 
 	return ""
 }
 
-func newestVersionedPath(paths []string) string {
-	var best string
-	var bestVersion []int
-	bestValid := false
-
-	for _, path := range paths {
-		versionParts, ok := parseVersionParts(versionFromPath(path))
-		switch {
-		case best == "":
-			best = path
-			bestVersion = versionParts
-			bestValid = ok
-		case ok && !bestValid:
-			best = path
-			bestVersion = versionParts
-			bestValid = true
-		case ok && bestValid:
-			if cmp := compareVersionParts(versionParts, bestVersion); cmp > 0 || (cmp == 0 && path > best) {
-				best = path
-				bestVersion = versionParts
-			}
-		case !ok && !bestValid && path > best:
-			best = path
-		}
-	}
-
-	return best
-}
-
-func versionFromPath(path string) string {
-	versionDir := filepath.Dir(filepath.Dir(path))
-	return filepath.Base(versionDir)
-}
-
-func parseVersionParts(version string) ([]int, bool) {
-	if version == "" {
-		return nil, false
-	}
-	parts := strings.Split(version, ".")
-	values := make([]int, 0, len(parts))
-	for _, part := range parts {
-		if part == "" {
-			return nil, false
-		}
-		value, err := strconv.Atoi(part)
-		if err != nil {
-			return nil, false
-		}
-		values = append(values, value)
-	}
-	return values, true
-}
-
-func compareVersionParts(left, right []int) int {
-	maxLen := len(left)
-	if len(right) > maxLen {
-		maxLen = len(right)
-	}
-	for i := 0; i < maxLen; i++ {
-		var l, r int
-		if i < len(left) {
-			l = left[i]
-		}
-		if i < len(right) {
-			r = right[i]
-		}
-		switch {
-		case l < r:
-			return -1
-		case l > r:
-			return 1
-		}
-	}
-	return 0
-}
+// newestVersionedPath / versionFromPath / parseVersionParts / compareVersionParts
+// used to be duplicated here. They now live as exported helpers in
+// cmd/mxcli/docker (docker.NewestVersionedPath). The integration-test harness
+// call-site was adjusted to use the exported helper instead.
 
 // copyFile copies a single file from src to dst.
 func copyFile(src, dst string) error {