refactor(completion): tighten the engine after a cleanup pass

`--temp-dir` was missing from the flag-to-directive map, so it fell back to plain file completion while `--dir` and `--remote-cache-dir` offered directories.

The rest is dead weight: `listTasks` re-defaulted a sorter `NewExecutor` already sets and scanned descriptions for templates even with `--no-descriptions`; `detectTaskName` had a `--` branch `Complete` returns before reaching; the two flag-value branches built the same suggestion slice twice. `os.Args[2:]` is now sliced in one place, `complete.Words()`, instead of three, and the test helpers reuse `slicesext.Convert`.

cmd/task/task.go

@@ -62,7 +62,7 @@ func run() error {
 	// Dispatched before flag validation: the args after __complete are the
 	// user's command line, not Task's own flags.
 	if complete.IsActive() {
-		return runComplete(os.Args[2:])
+		return runComplete(complete.Words())
 	}
 
 	log := &logger.Logger{

internal/complete/complete.go

@@ -10,6 +10,11 @@ func IsActive() bool {
 	return len(os.Args) >= 2 && os.Args[1] == CommandName
 }
 
+// Words returns the command line being completed: the args after __complete.
+func Words() []string {
+	return os.Args[2:]
+}
+
 // Directive mirrors cobra's ShellCompDirective bitfield, emitted as `:<n>`.
 type Directive int
 

internal/complete/complete_test.go

@@ -12,6 +12,7 @@ import (
 
 	"github.com/go-task/task/v3"
 	"github.com/go-task/task/v3/internal/complete"
+	"github.com/go-task/task/v3/internal/slicesext"
 )
 
 func newTestFlagSet() *pflag.FlagSet {
@@ -23,6 +24,7 @@ func newTestFlagSet() *pflag.FlagSet {
 	fs.BoolVarP(&b, "verbose", "v", false, "Verbose mode")
 	fs.StringVarP(&s, "taskfile", "t", "", "Taskfile path")
 	fs.StringVarP(&s, "dir", "d", "", "Run dir")
+	fs.StringVar(&s, "temp-dir", "", "Temp dir")
 	fs.StringVarP(&s, "output", "o", "", "Output style")
 	fs.StringVar(&s, "sort", "", "Sort order")
 	fs.StringVar(&s, "cacert", "", "CA cert path")
@@ -282,6 +284,14 @@ func TestComplete_PathFlag_Dir(t *testing.T) {
 	require.Equal(t, complete.DirectiveFilterDirs, dir)
 }
 
+func TestComplete_PathFlag_TempDir(t *testing.T) {
+	t.Parallel()
+
+	suggs, dir := complete.Complete(setupExecutor(t), newTestFlagSet(), []string{"--temp-dir", ""}, complete.Options{})
+	require.Empty(t, suggs)
+	require.Equal(t, complete.DirectiveFilterDirs, dir)
+}
+
 func TestComplete_PathFlag_Cacert(t *testing.T) {
 	t.Parallel()
 
@@ -435,17 +445,9 @@ func TestWrite_EmptyWithDirective(t *testing.T) {
 }
 
 func values(suggs []complete.Suggestion) []string {
-	out := make([]string, 0, len(suggs))
-	for _, s := range suggs {
-		out = append(out, s.Value)
-	}
-	return out
+	return slicesext.Convert(suggs, func(s complete.Suggestion) string { return s.Value })
 }
 
 func descriptions(suggs []complete.Suggestion) []string {
-	out := make([]string, 0, len(suggs))
-	for _, s := range suggs {
-		out = append(out, s.Description)
-	}
-	return out
+	return slicesext.Convert(suggs, func(s complete.Suggestion) string { return s.Description })
 }

internal/complete/context.go

@@ -56,9 +56,6 @@ func detectTaskName(args []string, knownTasks []string, fs *pflag.FlagSet) strin
 			skipNext = false
 			continue
 		}
-		if w == "--" {
-			return taskName
-		}
 		if strings.HasPrefix(w, "-") {
 			if !strings.Contains(w, "=") {
 				if f := matchFlagName(fs, w); f != nil && flagTakesValue(f) {

internal/complete/engine.go

@@ -8,7 +8,6 @@ import (
 	"github.com/go-task/task/v3"
 	"github.com/go-task/task/v3/internal/refs"
 	"github.com/go-task/task/v3/internal/slicesext"
-	"github.com/go-task/task/v3/internal/sort"
 	"github.com/go-task/task/v3/taskfile/ast"
 )
 
@@ -123,22 +122,17 @@ func completeTaskNames(e *task.Executor, opts Options) ([]Suggestion, Directive)
 // GetTaskList compiles every task, on every keystroke, and a description is the
 // only compiled field read: worth its cost only when one holds a template.
 func listTasks(e *task.Executor, opts Options) []*ast.Task {
-	sorter := e.TaskSorter
-	if sorter == nil {
-		sorter = sort.AlphaNumericWithRootTasksFirst
-	}
-
 	out := make([]*ast.Task, 0, e.Taskfile.Tasks.Len())
 	templated := false
-	for t := range e.Taskfile.Tasks.Values(sorter) {
+	for t := range e.Taskfile.Tasks.Values(e.TaskSorter) {
 		if t.Internal {
 			continue
 		}
-		templated = templated || strings.Contains(t.Desc, "{{")
+		templated = templated || (!opts.NoDescriptions && strings.Contains(t.Desc, "{{"))
 		out = append(out, t)
 	}
 
-	if !opts.NoDescriptions && templated {
+	if templated {
 		// The uncompiled tasks keep one broken task from emptying the list.
 		if compiled, err := e.GetTaskList(task.FilterOutInternal); err == nil {
 			return compiled
@@ -160,24 +154,24 @@ func completeFlagValue(flagName, prefix string) ([]Suggestion, Directive) {
 	// An absent key yields DirectiveDefault, falling through to the enums.
 	switch flagDirective[flagName] {
 	case DirectiveFilterFileExt:
-		exts := slicesext.Convert(taskfileExtensions, func(ext string) Suggestion {
-			return Suggestion{Value: ext}
-		})
-		return exts, DirectiveFilterFileExt
+		return suggest("", taskfileExtensions), DirectiveFilterFileExt
 	case DirectiveFilterDirs:
 		return nil, DirectiveFilterDirs
 	}
 
 	if values, ok := flagEnums[flagName]; ok {
-		out := slicesext.Convert(values, func(v string) Suggestion {
-			return Suggestion{Value: prefix + v}
-		})
-		return out, DirectiveNoFileComp
+		return suggest(prefix, values), DirectiveNoFileComp
 	}
 
 	return nil, DirectiveDefault
 }
 
+func suggest(prefix string, values []string) []Suggestion {
+	return slicesext.Convert(values, func(v string) Suggestion {
+		return Suggestion{Value: prefix + v}
+	})
+}
+
 func completeTaskVars(e *task.Executor, taskName string) ([]Suggestion, Directive) {
 	compiled, err := e.FastCompiledTask(&task.Call{Task: taskName})
 	if err != nil || compiled == nil || compiled.Requires == nil {

internal/complete/flags.go

@@ -23,6 +23,7 @@ var flagDirective = map[string]Directive{
 	"taskfile":         DirectiveFilterFileExt,
 	"dir":              DirectiveFilterDirs,
 	"remote-cache-dir": DirectiveFilterDirs,
+	"temp-dir":         DirectiveFilterDirs,
 }
 
 var taskfileExtensions = []string{"yml", "yaml"}

internal/flags/flags.go

@@ -181,7 +181,7 @@ func init() {
 	// flags deciding which Taskfile is loaded must still reach the engine.
 	// ContinueOnError keeps what was parsed and prints nothing.
 	if complete.IsActive() {
-		_, words := complete.ParseOptions(os.Args[2:])
+		_, words := complete.ParseOptions(complete.Words())
 		pflag.CommandLine.Init(pflag.CommandLine.Name(), pflag.ContinueOnError)
 		pflag.CommandLine.ParseErrorsAllowlist.UnknownFlags = true
 		_ = pflag.CommandLine.Parse(words)