review: address code review feedback on startup TUI and env_when

- Use errors.New instead of fmt.Errorf for sentinel with no wrapping
- Remove no-op hintTextStyle, apply hint text directly
- Document splitErrHint convention for startup check implementors
- Document env/env_when priority in buildEnv
- Add test for feature gate env_when validation
- Add test for multi-level template env_when inheritance

Author: LauJosefsen

actions/runner.go

@@ -357,6 +357,8 @@ func buildEnv(cfg *config.GitteConfig, st *state.GitteState, projName string, pr
 	for k, v := range projEnv {
 		envMap[k] = v
 	}
+	// env_when overrides env for the same key on matching arch; on non-matching
+	// arch the key from env remains (or is absent if not in env).
 	for k, v := range projEnvWhen {
 		envMap[k] = v
 	}

config/template_test.go

@@ -372,3 +372,40 @@ func TestResolveTemplates_EnvWhenMergeDisjointKeys(t *testing.T) {
 		t.Error("expected FROM_PROJECT from project")
 	}
 }
+
+func TestResolveTemplates_EnvWhenMultiLevelInheritance(t *testing.T) {
+	// grandparent → parent → project: env_when propagates through the chain.
+	cfg := &GitteConfig{
+		Templates: map[string]Template{
+			"grandparent": {
+				EnvWhen: map[string]EnvWhenEntry{
+					"FROM_GRANDPARENT": {Value: "gp"},
+				},
+			},
+			"parent": {
+				Extends: []string{"grandparent"},
+				EnvWhen: map[string]EnvWhenEntry{
+					"FROM_PARENT": {Value: "p"},
+				},
+			},
+		},
+		Projects: map[string]ProjectConfig{
+			"myservice": {
+				Remote:  "git@github.com:example/myservice.git",
+				Extends: "parent",
+			},
+		},
+	}
+
+	if err := ResolveTemplates(cfg); err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	proj := cfg.Projects["myservice"]
+	if proj.EnvWhen["FROM_GRANDPARENT"].Value != "gp" {
+		t.Errorf("expected FROM_GRANDPARENT to propagate through parent, got %v", proj.EnvWhen)
+	}
+	if proj.EnvWhen["FROM_PARENT"].Value != "p" {
+		t.Errorf("expected FROM_PARENT in resolved project, got %v", proj.EnvWhen)
+	}
+}

config/validate_test.go

@@ -143,3 +143,38 @@ func TestValidateConfig_EnvWhenValidArchType(t *testing.T) {
 		t.Errorf("expected no errors, got: %v", result.Errors)
 	}
 }
+
+func TestValidateConfig_EnvWhenFeatureGateUnknownConditionType(t *testing.T) {
+	cfg := &GitteConfig{
+		FeatureGates: map[string]FeatureGate{
+			"my-feature": {
+				Effects: FeatureEffects{
+					EnvWhen: map[string]EnvWhenEntry{
+						"FOO": {
+							Value: "bar",
+							Conditions: []EnvWhenCondition{
+								{Type: "not_a_real_type"},
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	result := ValidateConfig(cfg)
+	if !result.HasErrors() {
+		t.Fatal("expected validation error for unknown condition type in feature gate")
+	}
+
+	found := false
+	for _, e := range result.Errors {
+		if strings.Contains(e.Field, "env_when") && strings.Contains(e.Message, "not_a_real_type") {
+			found = true
+			break
+		}
+	}
+	if !found {
+		t.Errorf("expected error mentioning env_when and 'not_a_real_type', got: %v", result.Errors)
+	}
+}

startup/startup.go

@@ -2,6 +2,7 @@ package startup
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"sort"
 
@@ -56,7 +57,7 @@ func Run(ctx context.Context, cfg *config.GitteConfig, cwd string, mode output.O
 	if runErr != nil && mode != output.ModePlain {
 		// TUI view already printed a human-readable failure summary; return a
 		// terse sentinel so root.go only prints "startup checks failed".
-		return fmt.Errorf("startup checks failed")
+		return errors.New("startup checks failed")
 	}
 	return runErr
 }

startup/view.go

@@ -158,7 +158,7 @@ func (v *tuiView) printFailureSummary() {
 		fmt.Printf(" %s %s  %s\n", failStyle.Render("✗"), failStyle.Render(f.name), dimStyle.Render(fmtDuration(f.elapsed)))
 		fmt.Printf("   %s\n", dimStyle.Render(f.errMsg))
 		if f.hint != "" {
-			fmt.Printf("   %s %s\n", hintLabelStyle.Render("hint:"), hintTextStyle.Render(f.hint))
+			fmt.Printf("   %s %s\n", hintLabelStyle.Render("hint:"), f.hint)
 		}
 		fmt.Println()
 	}
@@ -175,7 +175,6 @@ var (
 	titleStyle     = lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("170"))
 	dimStyle       = lipgloss.NewStyle().Foreground(lipgloss.Color("241"))
 	hintLabelStyle = lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("214"))
-	hintTextStyle  = lipgloss.NewStyle()
 )
 
 var spinnerFrames = []string{"⠋", "⠙", "⠹", "⠸", "⠼", "⠴", "⠦", "⠧", "⠇", "⠏"}
@@ -397,6 +396,8 @@ func truncateToVisualWidth(s string, maxWidth int) string {
 
 // splitErrHint splits an error message of the form "msg\nhint: hint" into its
 // two parts. If there is no hint suffix the second return value is empty.
+// Startup checks emit hints by appending "\nhint: <text>" to their error
+// message (see startup.go where checks call check.GetHint()).
 func splitErrHint(err error) (string, string) {
 	const sep = "\nhint: "
 	msg := err.Error()