feat(generators): treat Client/client as reserved symbols with collision warning

Flag keys that transform to a reserved generator symbol (Client in Go,
client in Node.js) are excluded from the generated output and a warning
is emitted at generation time. Documents the reserved symbols per
generator in the generators README.

Author: kriscoleman

internal/generators/README.md

@@ -55,4 +55,23 @@ To add a new generator, follow these steps:
 6. Write tests for your generator to ensure it works as expected.
 7. Update the documentation to include information about your new generator.
 
-We appreciate your contributions and look forward to seeing your new generators!
+We appreciate your contributions and look forward to seeing your new generators!
+
+## Reserved Keywords
+
+Each generator reserves certain symbol names that it exports in the generated output. If a flag key transforms to a reserved name, that flag will be **excluded** from the generated output and a warning will be printed.
+
+| Generator | Reserved names | Transform applied |
+|-----------|---------------|-------------------|
+| Go        | `Client`      | `ToPascal`        |
+| Node.js   | `client`      | `ToCamel`         |
+
+For example, a flag key `"client"` in a Go manifest would transform to `Client` (via `ToPascal`), colliding with the exported `var Client` that the Go generator places in every generated file. The flag will be skipped and the following warning emitted:
+
+```
+Flag "client" transforms to "Client" which is a reserved symbol in the Go generator. This flag will be excluded from the generated output.
+```
+
+To avoid this, rename any flags whose transformed name matches a reserved symbol.
+
+When adding a new generator, document its reserved names in the table above and enforce them in the generator's `Generate()` method using the same pattern.

internal/generators/golang/golang.go

@@ -10,8 +10,10 @@ import (
 	"strings"
 	"text/template"
 
+	"github.com/iancoleman/strcase"
 	"github.com/open-feature/cli/internal/flagset"
 	"github.com/open-feature/cli/internal/generators"
+	"github.com/open-feature/cli/internal/logger"
 	"golang.org/x/tools/imports"
 )
 
@@ -128,7 +130,28 @@ func formatNestedValue(value any) string {
 	}
 }
 
+// reservedNames are symbols exported by the Go generator itself. Flag keys
+// that transform (via ToPascal) to one of these names will be excluded from
+// the generated output and a warning will be emitted.
+var reservedNames = map[string]bool{
+	"Client": true,
+}
+
 func (g *GolangGenerator) Generate(params *generators.Params[Params]) error {
+	filtered := &flagset.Flagset{}
+	for _, flag := range g.Flagset.Flags {
+		transformed := strcase.ToCamel(flag.Key)
+		if reservedNames[transformed] {
+			logger.Default.Warning(fmt.Sprintf(
+				"Flag %q transforms to %q which is a reserved symbol in the Go generator. This flag will be excluded from the generated output.",
+				flag.Key, transformed,
+			))
+			continue
+		}
+		filtered.Flags = append(filtered.Flags, flag)
+	}
+	g.Flagset = filtered
+
 	funcs := template.FuncMap{
 		"SupportImports":  supportImports,
 		"OpenFeatureType": openFeatureType,

internal/generators/nodejs/nodejs.go

@@ -3,10 +3,13 @@ package nodejs
 import (
 	_ "embed"
 	"encoding/json"
+	"fmt"
 	"text/template"
 
+	"github.com/iancoleman/strcase"
 	"github.com/open-feature/cli/internal/flagset"
 	"github.com/open-feature/cli/internal/generators"
+	"github.com/open-feature/cli/internal/logger"
 )
 
 type NodejsGenerator struct {
@@ -43,7 +46,28 @@ func toJSONString(value any) string {
 	return string(bytes)
 }
 
+// reservedNames are symbols exported by the Node.js generator itself. Flag
+// keys that transform (via ToCamel) to one of these names will be excluded
+// from the generated output and a warning will be emitted.
+var reservedNames = map[string]bool{
+	"client": true,
+}
+
 func (g *NodejsGenerator) Generate(params *generators.Params[Params]) error {
+	filtered := &flagset.Flagset{}
+	for _, flag := range g.Flagset.Flags {
+		transformed := strcase.ToLowerCamel(flag.Key)
+		if reservedNames[transformed] {
+			logger.Default.Warning(fmt.Sprintf(
+				"Flag %q transforms to %q which is a reserved symbol in the Node.js generator. This flag will be excluded from the generated output.",
+				flag.Key, transformed,
+			))
+			continue
+		}
+		filtered.Flags = append(filtered.Flags, flag)
+	}
+	g.Flagset = filtered
+
 	funcs := template.FuncMap{
 		"OpenFeatureType": openFeatureType,
 		"ToJSONString":    toJSONString,