feat: set merge method to: merge | semi_linear | ff

config/assignment.go

@@ -57,6 +57,7 @@ func GetAssignmentConfig(course, assignment string, onlyForStudentsOrGroups ...s
 		Description:           description(assignmentKey),
 		ContainerRegistry:     containerRegistry,
 		AccessLevel:           accessLevel(assignmentKey),
+		MergeRequest:          mergeRequest(assignmentKey),
 		Students:              students(per, course, assignment, onlyForStudentsOrGroups...),
 		Groups:                groups(per, course, assignment, onlyForStudentsOrGroups...),
 		Startercode:           startercode(assignmentKey),
@@ -134,3 +135,17 @@ func description(assignmentKey string) string {
 
 	return description
 }
+
+func mergeRequest(assignmentKey string) *MergeRequest {
+	mergeMethod := MergeCommit
+	switch viper.GetString(assignmentKey + ".mergeRequest.mergeMethod") {
+	case "semi_linear":
+		mergeMethod = SemiLinearHistory
+	case "ff":
+		mergeMethod = FastForward
+	case "merge":
+		mergeMethod = MergeCommit
+	}
+
+	return &MergeRequest{MergeMethod: mergeMethod}
+}

config/assignment_test.go

@@ -94,6 +94,8 @@ func TestGetAssignmentConfig(t *testing.T) {
 	viper.Set("course.a1.assignmentpath", "blatt-01")
 	viper.Set("course.a1.per", "student")
 	viper.Set("course.a1.description", "blatt 1")
+	viper.Set("course.a1.mergeRequest", map[string]any{"mergeMethod": "semi_linear"})
+	viper.Set("course.a1.mergeRequest.mergeMethod", "semi_linear")
 	viper.Set("course.a1.release", map[string]any{"dockerImages": []string{"registry/app"}})
 	viper.Set("course.a1.release.dockerImages", []string{"registry/app"})
 
@@ -123,4 +125,26 @@ func TestGetAssignmentConfig(t *testing.T) {
 	if cfg.AccessLevel != Developer {
 		t.Fatalf("AccessLevel = %v, want %v", cfg.AccessLevel, Developer)
 	}
+	if cfg.MergeRequest == nil || cfg.MergeRequest.MergeMethod != SemiLinearHistory {
+		t.Fatalf("MergeRequest = %#v, want semi_linear", cfg.MergeRequest)
+	}
+}
+
+func TestGetAssignmentConfig_DefaultMergeRequest(t *testing.T) {
+	resetViper(t)
+
+	viper.Set("gitlab.host", "https://gitlab.example.org")
+	viper.Set("course", true)
+	viper.Set("course.coursepath", "mpd")
+	viper.Set("course.a1", true)
+	viper.Set("course.a1.assignmentpath", "blatt-01")
+
+	cfg := GetAssignmentConfig("course", "a1")
+
+	if cfg.MergeRequest == nil {
+		t.Fatal("MergeRequest should be initialized with defaults")
+	}
+	if cfg.MergeRequest.MergeMethod != MergeCommit {
+		t.Fatalf("MergeRequest.MergeMethod = %q, want %q", cfg.MergeRequest.MergeMethod, MergeCommit)
+	}
 }

config/release.go

@@ -14,12 +14,12 @@ func release(assignmentKey string) *Release {
 	}
 
 	return &Release{
-		MergeRequest: mergeRequest(assignmentKey),
+		MergeRequest: releaseMergeRequest(assignmentKey),
 		DockerImages: dockerImages(assignmentKey),
 	}
 }
 
-func mergeRequest(assignmentKey string) *MergeRequest {
+func releaseMergeRequest(assignmentKey string) *ReleaseMergeRequest {
 	mergeRequestMap := viper.GetStringMapString(assignmentKey + ".release.mergeRequest")
 	if len(mergeRequestMap) == 0 {
 		log.Debug().Str("assignmemtKey", assignmentKey).Msg("no release by merge request provided")
@@ -36,7 +36,7 @@ func mergeRequest(assignmentKey string) *MergeRequest {
 		targetBranch = tB
 	}
 
-	return &MergeRequest{
+	return &ReleaseMergeRequest{
 		SourceBranch: sourceBranch,
 		TargetBranch: targetBranch,
 		HasPipeline:  viper.GetBool(assignmentKey + ".release.mergeRequest.pipeline"),

config/show.go

@@ -13,6 +13,16 @@ func (cfg *AssignmentConfig) Show() {
 		containerRegistry = aurora.Green("enabled")
 	}
 
+	mergeMethod := MergeCommit
+	if cfg.MergeRequest != nil {
+		mergeMethod = cfg.MergeRequest.MergeMethod
+	}
+	mergeRequestCfg := aurora.Sprintf(aurora.Cyan(`
+  %s      %s`),
+		aurora.Cyan("MergeMethod:"),
+		aurora.Yellow(mergeMethod),
+	)
+
 	startercode := aurora.Sprintf(aurora.Red("not defined"))
 	if cfg.Startercode != nil {
 		issueNumbers := aurora.Sprintf(aurora.Red("not defined"))
@@ -71,9 +81,9 @@ func (cfg *AssignmentConfig) Show() {
 	}
 	release := aurora.Sprintf(aurora.Red("not defined"))
 	if cfg.Release != nil {
-		mergeRequest := aurora.Sprintf(aurora.Red("not defined"))
+		releaseMergeRequest := aurora.Sprintf(aurora.Red("not defined"))
 		if cfg.Release.MergeRequest != nil {
-			mergeRequest = aurora.Sprintf(`
+			releaseMergeRequest = aurora.Sprintf(`
     %s   %s
     %s   %s
     %s       %t`,
@@ -100,7 +110,7 @@ func (cfg *AssignmentConfig) Show() {
   %s     %s
   %s     %s`),
 			aurora.Cyan("MergeRequest:"),
-			mergeRequest,
+			releaseMergeRequest,
 			aurora.Cyan("DockerImages:"),
 			dockerImages,
 		)
@@ -142,7 +152,8 @@ Per:                %s
 Base-URL:           %s
 Description:	    %s
 AccessLevel:        %s
-Container-Registry: %s
+MergeRequest:       %s
+%s %s
 Startercode:        %s
 Seeding:            %s
 Release:            %s
@@ -156,6 +167,8 @@ Release:            %s
 		aurora.Yellow(cfg.URL),
 		aurora.Yellow(cfg.Description),
 		aurora.Yellow(cfg.AccessLevel.String()),
+		mergeRequestCfg,
+		aurora.Cyan("Container-Registry:"),
 		containerRegistry,
 		aurora.Yellow(startercode),
 		aurora.Yellow(seeding),

config/types.go

@@ -19,6 +19,7 @@ type AssignmentConfig struct {
 	Description           string
 	ContainerRegistry     bool
 	AccessLevel           AccessLevel
+	MergeRequest          *MergeRequest
 	Students              []*Student
 	Groups                []*Group
 	Startercode           *Startercode
@@ -64,11 +65,15 @@ type Clone struct {
 }
 
 type Release struct {
-	MergeRequest *MergeRequest
+	MergeRequest *ReleaseMergeRequest
 	DockerImages []string
 }
 
 type MergeRequest struct {
+	MergeMethod MergeMethod
+}
+
+type ReleaseMergeRequest struct {
 	SourceBranch string
 	TargetBranch string
 	HasPipeline  bool
@@ -87,3 +92,16 @@ const (
 	Developer  AccessLevel = 30
 	Maintainer AccessLevel = 40
 )
+
+// MergeMethod represents the merge strategy for GitLab projects.
+// Values correspond to glabs config format, not the GitLab API directly.
+type MergeMethod string
+
+const (
+	// MergeCommit creates a merge commit for every merge (GitLab default).
+	MergeCommit MergeMethod = "merge"
+	// SemiLinearHistory requires linear history: rebase before creating merge commit.
+	SemiLinearHistory MergeMethod = "semi_linear"
+	// FastForward only allows fast-forward merges; no merge commits.
+	FastForward MergeMethod = "ff"
+)

config/urls_show_test.go

@@ -144,7 +144,7 @@ func TestShow_WithClone(t *testing.T) {
 func TestShow_WithRelease_MergeRequestAndDockerImages(t *testing.T) {
 	cfg := &AssignmentConfig{
 		Release: &Release{
-			MergeRequest: &MergeRequest{
+			MergeRequest: &ReleaseMergeRequest{
 				SourceBranch: "develop",
 				TargetBranch: "main",
 				HasPipeline:  true,
@@ -158,7 +158,7 @@ func TestShow_WithRelease_MergeRequestAndDockerImages(t *testing.T) {
 func TestShow_WithRelease_MergeRequestOnly(t *testing.T) {
 	cfg := &AssignmentConfig{
 		Release: &Release{
-			MergeRequest: &MergeRequest{
+			MergeRequest: &ReleaseMergeRequest{
 				SourceBranch: "develop",
 				TargetBranch: "main",
 			},
@@ -225,3 +225,19 @@ func TestShow_PerGroup_ListsGroups(t *testing.T) {
 		t.Fatalf("Show(PerGroup) output does not contain team1: %q", out)
 	}
 }
+
+func TestShow_WithMergeMethod(t *testing.T) {
+	cfg := &AssignmentConfig{
+		MergeRequest: &MergeRequest{MergeMethod: SemiLinearHistory},
+	}
+	out := captureStdout(t, func() { cfg.Show() })
+	if !strings.Contains(out, "MergeRequest:") {
+		t.Fatalf("Show() output does not contain MergeRequest header: %q", out)
+	}
+	if !strings.Contains(out, "MergeMethod:") {
+		t.Fatalf("Show() output does not contain nested MergeMethod key: %q", out)
+	}
+	if !strings.Contains(out, "semi_linear") {
+		t.Fatalf("Show() output does not contain merge method semi_linear: %q", out)
+	}
+}

docs/configuration.md

@@ -121,6 +121,8 @@ Patterns are **regular expressions**, so:
     per: student
     accesslevel: developer
     containerRegistry: false
+    mergeRequest:
+      mergeMethod: merge        # merge | semi_linear | ff
 
     startercode:
       ...
@@ -141,6 +143,7 @@ Patterns are **regular expressions**, so:
 | `description` | GitLab project description | `generated by glabs` | Visible in UI |
 | `accesslevel` | Initial project access (see below) | `developer` | Can be changed later with `setaccess` |
 | `containerRegistry` | Enable container registry | `false` | Auto-enabled if `release.dockerImages` set |
+| `mergeRequest.mergeMethod` | Merge strategy (see below) | `merge` | Applied at project creation |
 | `students` | Override/add assignment-specific students | — | Merged with course-level |
 | `groups` | Override/add assignment-specific groups | — | Merged with course-level |
 
@@ -306,6 +309,24 @@ release:
 | `mergeRequest.pipeline` | Wait for CI | `false` | Require passing checks |
 | `dockerImages` | Images to build | `[]` | Creates container registry entries |
 
+### Merge method values
+
+The assignment-level `mergeRequest.mergeMethod` option controls how merge requests are merged in every generated project:
+
+| Value | GitLab UI name | Description |
+|---|---|---|
+| `merge` | Merge commit | Always create a merge commit (GitLab default) |
+| `semi_linear` | Merge commit with semi-linear history | Require a linear history; fast-forward commits are rebased before merge |
+| `ff` | Fast-forward merge | No merge commits; only fast-forward merges allowed |
+
+**Example:**
+
+```yaml
+blatt01:
+  mergeRequest:
+    mergeMethod: ff   # Students must keep a linear history
+```
+
 **Notes:**
 
 - Container registry is auto-enabled when `dockerImages` is set

gitlab/integration_gitlab_test.go

@@ -324,6 +324,59 @@ func TestIntegration_GitLab_Operations(t *testing.T) {
 			t.Fatalf("expected user %q to be a project member after Setaccess()", itUsername)
 		}
 	})
+
+	// ── Sub-test: MergeMethod ─────────────────────────────────────────────────
+	t.Run("MergeMethod", func(t *testing.T) {
+		cases := []struct {
+			subPath     string
+			mergeMethod config.MergeMethod
+			wantGitLab  gitlabapi.MergeMethodValue
+		}{
+			{"mergemethod-merge-a1", config.MergeCommit, gitlabapi.NoFastForwardMerge},
+			{"mergemethod-semi-a1", config.SemiLinearHistory, gitlabapi.RebaseMerge},
+			{"mergemethod-ff-a1", config.FastForward, gitlabapi.FastForwardMerge},
+		}
+
+		for _, tc := range cases {
+			tc := tc
+			t.Run(string(tc.mergeMethod), func(t *testing.T) {
+				un := "student1"
+				path := parent.FullPath + "/" + tc.subPath
+				cfg := &config.AssignmentConfig{
+					Course:            "it",
+					Name:              "a1",
+					Path:              path,
+					URL:               baseURL + "/" + path,
+					Per:               config.PerStudent,
+					Description:       "merge method integration test",
+					ContainerRegistry: false,
+					MergeRequest:      &config.MergeRequest{MergeMethod: tc.mergeMethod},
+					Students:          []*config.Student{{Username: &un, Raw: un}},
+				}
+
+				groupID, err := client.createGroup(cfg)
+				if err != nil {
+					t.Fatalf("createGroup(%q) failed: %v", tc.subPath, err)
+				}
+
+				repoName := cfg.RepoNameWithSuffix(un)
+				project, _, err := client.generateProject(cfg, repoName, groupID)
+				if err != nil {
+					t.Fatalf("generateProject failed: %v", err)
+				}
+
+				projectPath := cfg.Path + "/" + repoName
+				proj, _, err := client.Projects.GetProject(projectPath, &gitlabapi.GetProjectOptions{})
+				if err != nil {
+					t.Fatalf("GetProject failed: %v", err)
+				}
+				_ = project
+				if proj.MergeMethod != tc.wantGitLab {
+					t.Fatalf("MergeMethod = %q, want %q", proj.MergeMethod, tc.wantGitLab)
+				}
+			})
+		}
+	})
 }
 
 func TestIntegration_GitLab_GroupAndProjectLifecycle(t *testing.T) {

gitlab/projects.go

@@ -11,6 +11,25 @@ import (
 
 func (c *Client) generateProject(assignmentCfg *config.AssignmentConfig, name string, inID int64) (*gitlab.Project, bool, error) {
 	generated := false
+
+	// Merge method should already be defaulted by config parsing.
+	// Keep this fallback for safety when AssignmentConfig is constructed manually.
+	mergeMethod := config.MergeCommit
+	if assignmentCfg.MergeRequest != nil {
+		mergeMethod = assignmentCfg.MergeRequest.MergeMethod
+	}
+
+	// Convert glabs MergeMethod to GitLab API MergeMethodValue
+	var gitlabMergeMethod gitlab.MergeMethodValue
+	switch mergeMethod {
+	case config.SemiLinearHistory:
+		gitlabMergeMethod = gitlab.RebaseMerge
+	case config.FastForward:
+		gitlabMergeMethod = gitlab.FastForwardMerge
+	default:
+		gitlabMergeMethod = gitlab.NoFastForwardMerge
+	}
+
 	p := &gitlab.CreateProjectOptions{
 		Name:                                  gitlab.Ptr(name),
 		Description:                           gitlab.Ptr(assignmentCfg.Description),
@@ -22,6 +41,7 @@ func (c *Client) generateProject(assignmentCfg *config.AssignmentConfig, name st
 		Visibility:                            gitlab.Ptr(gitlab.PrivateVisibility),
 		ContainerRegistryEnabled:              gitlab.Ptr(assignmentCfg.ContainerRegistry),
 		OnlyAllowMergeIfAllStatusChecksPassed: gitlab.Ptr(false),
+		MergeMethod:                           gitlab.Ptr(gitlabMergeMethod),
 	}
 
 	project, _, err := c.Projects.CreateProject(p)

gitlab/report_contract_test.go

@@ -159,7 +159,7 @@ func TestReport_HappyPath_WithRelease(t *testing.T) {
 		Path:   "mpd/ss26/blatt-01",
 		URL:    "https://gitlab.example.org/mpd/ss26/blatt-01",
 		Release: &config.Release{
-			MergeRequest: &config.MergeRequest{SourceBranch: "develop", TargetBranch: "main"},
+			MergeRequest: &config.ReleaseMergeRequest{SourceBranch: "develop", TargetBranch: "main"},
 			DockerImages: []string{"myimage:latest"},
 		},
 	}

gitlab/report_helper_contract_test.go

@@ -78,7 +78,7 @@ func TestProjectReport_AggregatesReleaseAndCommitData(t *testing.T) {
 
 	assignmentCfg := &config.AssignmentConfig{
 		Release: &config.Release{
-			MergeRequest: &config.MergeRequest{
+			MergeRequest: &config.ReleaseMergeRequest{
 				SourceBranch: "develop",
 				TargetBranch: "main",
 				HasPipeline:  true,