fix: help <TAB> offers operator topics, not 'help help'

When user types 'help ' (with trailing space), the completer now
offers help topic completions (+, dup, swap, etc.). Just 'help'
without a space still completes the command normally.

Also skip 'help' itself from GetCompletionTopics to avoid
suggesting 'help help'.

2 files changed, 30 insertions, 3 deletions

diff --git a/internal/repl/completer.go b/internal/repl/completer.go
index ccb4a33..f87209b 100644
--- a/internal/repl/completer.go
+++ b/internal/repl/completer.go
@@ -50,7 +50,7 @@ func NewAutoCompleter() *AutoCompleteAdapter {
 
 // Do implements the readline.AutoCompleter interface.
 // It returns matching command completions for the given line.
-// When the first word is "help", it offers help topic completions.
+// When the first word is "help" followed by a space, it offers help topic completions.
 func (a *AutoCompleteAdapter) Do(line []rune, pos int) ([][]rune, int) {
 	text := string(line[:pos])
 	words := strings.Fields(text)
@@ -58,7 +58,16 @@ func (a *AutoCompleteAdapter) Do(line []rune, pos int) ([][]rune, int) {
 		return a.completeCommands("")
 	}
 
-	// If first word is "help", complete help topics
+	// If first word is "help" and user typed a space after it (or more words),
+	// complete help topics. If first word is just "help" with no trailing space,
+	// complete the command "help".
+	if strings.ToLower(words[0]) == "help" && len(words) == 1 {
+		// Check if there's a trailing space — means user wants topics
+		if len(text) > 0 && text[len(text)-1] == ' ' {
+			return a.completeHelpTopics("")
+		}
+		// No trailing space — just completing the command "help"
+	}
 	if strings.ToLower(words[0]) == "help" && len(words) > 1 {
 		return a.completeHelpTopics(words[len(words)-1])
 	}
diff --git a/internal/repl/help_test.go b/internal/repl/help_test.go
index 9813ebb..b537c61 100644
--- a/internal/repl/help_test.go
+++ b/internal/repl/help_test.go
@@ -222,8 +222,26 @@ func TestHelpCompleterIntegration(t *testing.T) {
 		t.Fatal("NewAutoCompleter returned nil")
 	}
 
+	// "help " (with trailing space) should offer help topics, not "help help"
+	matches, _ := adapter.Do([]rune("help "), 5)
+	for _, m := range matches {
+		if string(m) == "help" {
+			t.Error("'help ' should not complete to 'help help'")
+		}
+	}
+	// Should include a known topic
+	foundPlus := false
+	for _, m := range matches {
+		if string(m) == "+" {
+			foundPlus = true
+		}
+	}
+	if !foundPlus {
+		t.Errorf("'help ' should suggest '+', got: %v", matches)
+	}
+
 	// Test help topic completion
-	matches, _ := adapter.Do([]rune("help +"), 6)
+	matches, _ = adapter.Do([]rune("help +"), 6)
 	if len(matches) != 1 {
 		t.Errorf("'help +' should match +, got %d matches: %v", len(matches), matches)
 	}