feat: move distribution builds to platform Docker builder

platform/config/config.go

@@ -4,12 +4,20 @@ import (
 	"bufio"
 	"os"
 	"path/filepath"
+	"strconv"
 	"strings"
 )
 
 const defaultAddr = ":8080"
 const defaultDataDir = ".platform-data"
 const defaultStorageBackend = "file"
+const defaultBuilderDockerBinary = "docker"
+
+// defaultBuilderImage names an explicit toolchain version rather than a
+// floating tag such as latest. Operators who want digest pinning override
+// PLATFORM_BUILDER_IMAGE with an image@sha256:... reference.
+const defaultBuilderImage = "browser-platform-distribution-builder:1.0.0"
+const defaultBuilderTimeoutSeconds = 1800
 
 type Config struct {
 	Addr                   string
@@ -24,6 +32,11 @@ type Config struct {
 	BootstrapAdminPassword string
 	SecretEnvelopeKey      string
 	AIProviderMode         string
+	BuilderDockerBinary    string
+	BuilderImage           string
+	BuilderSourceDir       string
+	BuilderWorkspaceDir    string
+	BuilderTimeoutSeconds  int
 }
 
 func Load() Config {
@@ -54,6 +67,10 @@ func Load() Config {
 		storageBackend = defaultStorageBackend
 	}
 	logBodyBackend := strings.TrimSpace(os.Getenv("PLATFORM_LOG_BODY_BACKEND"))
+	builderWorkspaceDir := strings.TrimSpace(os.Getenv("PLATFORM_BUILDER_WORKSPACE_DIR"))
+	if builderWorkspaceDir == "" {
+		builderWorkspaceDir = filepath.Join(dataDir, "distribution-builds")
+	}
 
 	return Config{
 		Addr:                   addr,
@@ -68,9 +85,22 @@ func Load() Config {
 		BootstrapAdminPassword: os.Getenv("PLATFORM_BOOTSTRAP_ADMIN_PASSWORD"),
 		SecretEnvelopeKey:      os.Getenv("PLATFORM_SECRET_ENVELOPE_KEY"),
 		AIProviderMode:         defaultString(strings.TrimSpace(os.Getenv("PLATFORM_AI_PROVIDER_MODE")), "live"),
+		BuilderDockerBinary:    defaultString(strings.TrimSpace(os.Getenv("PLATFORM_BUILDER_DOCKER_BINARY")), defaultBuilderDockerBinary),
+		BuilderImage:           defaultString(strings.TrimSpace(os.Getenv("PLATFORM_BUILDER_IMAGE")), defaultBuilderImage),
+		BuilderSourceDir:       strings.TrimSpace(os.Getenv("PLATFORM_BUILDER_SOURCE_DIR")),
+		BuilderWorkspaceDir:    builderWorkspaceDir,
+		BuilderTimeoutSeconds:  defaultPositiveInt(strings.TrimSpace(os.Getenv("PLATFORM_BUILDER_TIMEOUT_SECONDS")), defaultBuilderTimeoutSeconds),
 	}
 }
 
+func defaultPositiveInt(value string, fallback int) int {
+	parsed, err := strconv.Atoi(value)
+	if err != nil || parsed <= 0 {
+		return fallback
+	}
+	return parsed
+}
+
 func defaultString(value, fallback string) string {
 	if value == "" {
 		return fallback