feat(settings): ambient_mode and ambient_cadence_secs fields

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/settings/settings_test.go

@@ -33,8 +33,10 @@ func TestSeedFromEnvReadsVars(t *testing.T) {
 	t.Setenv("KEEL_MARVIN_CMD", "uv run am")
 	t.Setenv("KEEL_KNOWLEDGE_FILE", "/tmp/k.md")
 	t.Setenv("KEEL_AW_URL", "http://aw.local:5600")
+	t.Setenv("KEEL_AMBIENT_MODE", "")
+	t.Setenv("KEEL_AMBIENT_CADENCE_SECS", "")
 	got := SeedFromEnv()
-	want := Settings{AIBackend: "codex", MarvinCmd: "uv run am", KnowledgePath: "/tmp/k.md", AWURL: "http://aw.local:5600"}
+	want := Settings{AIBackend: "codex", MarvinCmd: "uv run am", KnowledgePath: "/tmp/k.md", AWURL: "http://aw.local:5600", AmbientMode: AmbientNotify, AmbientCadenceSecs: 300}
 	if got != want {
 		t.Errorf("SeedFromEnv = %+v, want %+v", got, want)
 	}
@@ -73,3 +75,38 @@ func TestSeedFromEnvAWURLDefault(t *testing.T) {
 		t.Fatalf("default AWURL = %q", got)
 	}
 }
+
+func TestValidAmbientMode(t *testing.T) {
+	for _, m := range []string{AmbientOff, AmbientStatus, AmbientNotify} {
+		if !ValidAmbientMode(m) {
+			t.Fatalf("%q should be valid", m)
+		}
+	}
+	if ValidAmbientMode("loud") {
+		t.Fatal("loud should be invalid")
+	}
+	if ValidAmbientMode("") {
+		t.Fatal("empty should be invalid (callers default before validating)")
+	}
+}
+
+func TestSeedFromEnvAmbientDefaults(t *testing.T) {
+	t.Setenv("KEEL_AMBIENT_MODE", "")
+	t.Setenv("KEEL_AMBIENT_CADENCE_SECS", "")
+	s := SeedFromEnv()
+	if s.AmbientMode != AmbientNotify {
+		t.Fatalf("ambient_mode default = %q, want %q", s.AmbientMode, AmbientNotify)
+	}
+	if s.AmbientCadenceSecs != 300 {
+		t.Fatalf("ambient_cadence_secs default = %d, want 300", s.AmbientCadenceSecs)
+	}
+}
+
+func TestSeedFromEnvAmbientFromEnv(t *testing.T) {
+	t.Setenv("KEEL_AMBIENT_MODE", "status")
+	t.Setenv("KEEL_AMBIENT_CADENCE_SECS", "120")
+	s := SeedFromEnv()
+	if s.AmbientMode != "status" || s.AmbientCadenceSecs != 120 {
+		t.Fatalf("env not honored: mode=%q cadence=%d", s.AmbientMode, s.AmbientCadenceSecs)
+	}
+}