feat(v0.3): add Projects filter to ListWorkspaces; fix last/delete

ListOpts gains a Projects bool that filters by EffectiveType.
Default behavior (Projects: false) now returns tasks only --
this is a deliberate semantic change that supports the new
'ctask list' (tasks) vs 'ctask list --projects' (projects)
spec.

The change silently regresses two cmd-level callers that scan
for "the most recently updated workspace": cmd/last.go (used by
'ctask last') and cmd/delete.go (used to print the "this was
your most recent workspace" note). Both are fixed by unioning a
tasks-scan with a projects-scan, so 'last' and 'delete' continue
to consider both types.

Test helper createTestWorkspaceTyped allows setting an explicit
type (or "" to simulate a v0.2 workspace with no type field).

internal/workspace/list.go

@@ -10,6 +10,11 @@ type ListOpts struct {
 	IncludeArchived bool
 	Category        string
 	Limit           int
+
+	// Projects, when true, returns project workspaces only. When false (default),
+	// only task workspaces are returned. v0.2 workspaces with no Type field are
+	// treated as tasks via EffectiveType.
+	Projects bool
 }
 
 // ListWorkspaces returns workspaces in reverse-chronological order.
@@ -19,6 +24,11 @@ func ListWorkspaces(root string, opts ListOpts) ([]QueryResult, error) {
 		return nil, err
 	}
 
+	wantType := "task"
+	if opts.Projects {
+		wantType = "project"
+	}
+
 	var filtered []QueryResult
 	for _, ws := range all {
 		if !opts.IncludeArchived && ws.Meta.Status == "archived" {
@@ -27,6 +37,9 @@ func ListWorkspaces(root string, opts ListOpts) ([]QueryResult, error) {
 		if opts.Category != "" && ws.Meta.Category != opts.Category {
 			continue
 		}
+		if EffectiveType(ws.Meta) != wantType {
+			continue
+		}
 		filtered = append(filtered, ws)
 	}
 

internal/workspace/list_test.go

@@ -47,6 +47,60 @@ func TestListWorkspaces(t *testing.T) {
 	}
 }
 
+func TestListProjectsFilter(t *testing.T) {
+	root := t.TempDir()
+	createTestWorkspaceTyped(t, root, "general", "2026-04-05_task-a", "active", "task")
+	createTestWorkspaceTyped(t, root, "general", "2026-04-04_task-b", "active", "") // legacy: no type -> task
+	createTestWorkspaceTyped(t, root, "projects", "2026-04-03_proj-a", "active", "project")
+	createTestWorkspaceTyped(t, root, "projects", "2026-04-02_proj-b", "archived", "project")
+
+	// Default: tasks only, active
+	results, err := ListWorkspaces(root, ListOpts{Limit: 20})
+	if err != nil {
+		t.Fatalf("ListWorkspaces: %v", err)
+	}
+	if len(results) != 2 {
+		t.Fatalf("expected 2 active tasks, got %d", len(results))
+	}
+	for _, r := range results {
+		if EffectiveType(r.Meta) != "task" {
+			t.Errorf("non-task in default list: %s (type %q)", r.Meta.Slug, r.Meta.Type)
+		}
+	}
+
+	// --projects: projects only, active
+	results, err = ListWorkspaces(root, ListOpts{Projects: true, Limit: 20})
+	if err != nil {
+		t.Fatalf("ListWorkspaces --projects: %v", err)
+	}
+	if len(results) != 1 {
+		t.Fatalf("expected 1 active project, got %d", len(results))
+	}
+	if results[0].Meta.Slug != "proj-a" {
+		t.Errorf("expected proj-a, got %s", results[0].Meta.Slug)
+	}
+
+	// --projects --all
+	results, err = ListWorkspaces(root, ListOpts{Projects: true, IncludeArchived: true, Limit: 20})
+	if err != nil {
+		t.Fatalf("ListWorkspaces --projects --all: %v", err)
+	}
+	if len(results) != 2 {
+		t.Fatalf("expected 2 projects with --all, got %d", len(results))
+	}
+
+	// --all alone: tasks only with archived
+	results, err = ListWorkspaces(root, ListOpts{IncludeArchived: true, Limit: 20})
+	if err != nil {
+		t.Fatalf("ListWorkspaces --all: %v", err)
+	}
+	for _, r := range results {
+		if EffectiveType(r.Meta) != "task" {
+			t.Errorf("--all alone returned non-task: %s", r.Meta.Slug)
+		}
+	}
+}
+
 func TestListReverseChronological(t *testing.T) {
 	root := t.TempDir()
 	createTestWorkspace(t, root, "general", "2026-04-01_first", "active")

internal/workspace/query_test.go

@@ -7,8 +7,15 @@ import (
 	"time"
 )
 
-// helper to create a minimal workspace for query testing
+// createTestWorkspace creates a minimal task workspace (Type defaults to "task")
+// for query/list testing.
 func createTestWorkspace(t *testing.T, root, category, dirName string, status string) {
+	createTestWorkspaceTyped(t, root, category, dirName, status, "task")
+}
+
+// createTestWorkspaceTyped creates a minimal workspace of an explicit type
+// (use "" to simulate a v0.2 workspace with no type field).
+func createTestWorkspaceTyped(t *testing.T, root, category, dirName, status, taskType string) {
 	t.Helper()
 	dir := filepath.Join(root, category, dirName)
 	os.MkdirAll(dir, 0755)
@@ -23,6 +30,7 @@ func createTestWorkspace(t *testing.T, root, category, dirName string, status st
 		UpdatedAt:     now,
 		Status:        status,
 		Category:      category,
+		Type:          taskType,
 		Mode:          "local",
 		Agent:         "claude",
 		WorkspacePath: dir,