diff --git a/internal/config/config.go b/internal/config/config.go
index c9b3d93..b93c192 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -83,6 +83,7 @@ type TagsConfig struct {
 type StateConfig struct {
 	Name  string `toml:"name"`
 	Color string `toml:"color"`
+	Done  bool   `toml:"done,omitempty"`
 }
 
 // StatesConfig holds TODO state configurations
@@ -163,7 +164,7 @@ func DefaultConfig() *Config {
 				{Name: "TODO", Color: "202"},
 				{Name: "PROG", Color: "220"},
 				{Name: "BLOCK", Color: "196"},
-				{Name: "DONE", Color: "34"},
+				{Name: "DONE", Color: "34", Done: true},
 			},
 			DefaultNewTaskState: "TODO",
 		},
@@ -393,6 +394,21 @@ func (c *Config) fillDefaults() {
 	// Note: We don't fill DefaultNewTaskState if States.States is non-empty because
 	// an empty string is a valid intentional value meaning "no default state".
 
+	// Back-compat: if states exist but none is flagged done (config predates the
+	// `done` field), treat the last state as done to preserve prior behavior.
+	if len(c.States.States) > 0 {
+		anyDone := false
+		for _, s := range c.States.States {
+			if s.Done {
+				anyDone = true
+				break
+			}
+		}
+		if !anyDone {
+			c.States.States[len(c.States.States)-1].Done = true
+		}
+	}
+
 	// Fill UI if zero values
 	if c.UI.HelpTextWidth == 0 {
 		c.UI.HelpTextWidth = defaults.UI.HelpTextWidth
@@ -511,6 +527,19 @@ func (c *Config) GetStateNames() []string {
 	return names
 }
 
+// IsDoneState reports whether the named state is configured as a done state.
+func (c *Config) IsDoneState(name string) bool {
+	if name == "" {
+		return false
+	}
+	for _, state := range c.States.States {
+		if state.Name == name {
+			return state.Done
+		}
+	}
+	return false
+}
+
 // UpdateKeybinding updates a keybinding in the configuration
 func (c *Config) UpdateKeybinding(action string, keys []string) error {
 	// Use reflection would be complex, so we handle specific cases
diff --git a/internal/config/config_test.go b/internal/config/config_test.go
new file mode 100644
index 0000000..3e22f80
--- /dev/null
+++ b/internal/config/config_test.go
@@ -0,0 +1,51 @@
+package config
+
+import "testing"
+
+func TestIsDoneState(t *testing.T) {
+	c := &Config{States: StatesConfig{States: []StateConfig{
+		{Name: "TODO", Color: "202"},
+		{Name: "DONE", Color: "34", Done: true},
+		{Name: "CANCELLED", Color: "240", Done: true},
+	}}}
+
+	cases := map[string]bool{"TODO": false, "DONE": true, "CANCELLED": true, "": false, "NOPE": false}
+	for name, want := range cases {
+		if got := c.IsDoneState(name); got != want {
+			t.Errorf("IsDoneState(%q) = %v, want %v", name, got, want)
+		}
+	}
+}
+
+func TestFillDefaultsMarksLastStateDoneWhenNoneFlagged(t *testing.T) {
+	c := &Config{States: StatesConfig{States: []StateConfig{
+		{Name: "TODO", Color: "202"},
+		{Name: "DONE", Color: "34"},
+	}}}
+	c.fillDefaults()
+
+	if c.States.States[len(c.States.States)-1].Name != "DONE" {
+		t.Fatalf("states reordered unexpectedly")
+	}
+	if !c.States.States[len(c.States.States)-1].Done {
+		t.Error("expected last state (DONE) to be flagged Done after migration")
+	}
+	if c.States.States[0].Done {
+		t.Error("expected first state (TODO) to remain not-done")
+	}
+}
+
+func TestFillDefaultsLeavesExplicitDoneFlagsAlone(t *testing.T) {
+	c := &Config{States: StatesConfig{States: []StateConfig{
+		{Name: "DONE", Color: "34", Done: true},
+		{Name: "TODO", Color: "202"},
+	}}}
+	c.fillDefaults()
+
+	if c.States.States[0].Name != "DONE" || !c.States.States[0].Done {
+		t.Error("explicit done flag on DONE should be preserved")
+	}
+	if c.States.States[1].Done {
+		t.Error("last state (TODO) must NOT be auto-flagged when a done state already exists")
+	}
+}