projection: begin the exact-path public epoch

The public tree and its history contain only the listed paths. Earlier projection history remains preserved internally.

Source-Sha: 913fde029b935671833254797f0f20f1eb9fabba

Policy-Sha: 913fde029b935671833254797f0f20f1eb9fabba

Tree-Digest: 180ae530c1058a2a5c89837bdce2d323ae83e669e38590ca72e75b8d92b7262f

agent/internal/version/version.go

@@ -0,0 +1,112 @@
+package version
+
+import (
+	"fmt"
+	"runtime"
+	"strings"
+	"time"
+)
+
+// Build-time injected version information (SERVER AUTHORITY)
+// Injected by server during build via ldflags
+var (
+	Version       = "dev" // Agent version (format: 0.1.26.0)
+	ConfigVersion = "dev" // Config schema version (format: 0, 1, 2, etc.)
+	BuildTime     = "unknown"
+	GitCommit     = "unknown"
+	GoVersion     = runtime.Version()
+)
+
+// ExtractConfigVersionFromAgent extracts the config version from the agent version
+// Agent version format: v0.1.23.6 where the fourth octet (.6) maps to config version
+// This provides the traditional mapping when only agent version is available
+func ExtractConfigVersionFromAgent(agentVer string) string {
+	// Strip 'v' prefix if present
+	cleanVersion := strings.TrimPrefix(agentVer, "v")
+
+	// Split version parts
+	parts := strings.Split(cleanVersion, ".")
+	if len(parts) == 4 {
+		// Return the fourth octet as the config version
+		// v0.1.23.6 → "6"
+		return parts[3]
+	}
+
+	// If we have a build-time injected ConfigVersion, use it
+	if ConfigVersion != "dev" {
+		return ConfigVersion
+	}
+
+	// Default fallback
+	return "6"
+}
+
+// Info holds complete version information
+type Info struct {
+	AgentVersion    string `json:"agent_version"`
+	ConfigVersion   string `json:"config_version"`
+	BuildTime       string `json:"build_time"`
+	GitCommit       string `json:"git_commit"`
+	GoVersion       string `json:"go_version"`
+	BuildTimestamp  int64  `json:"build_timestamp"`
+}
+
+// GetInfo returns complete version information
+func GetInfo() Info {
+	// Parse build time if available
+	timestamp := time.Now().Unix()
+	if BuildTime != "unknown" {
+		if t, err := time.Parse(time.RFC3339, BuildTime); err == nil {
+			timestamp = t.Unix()
+		}
+	}
+
+	return Info{
+		AgentVersion:   Version,
+		ConfigVersion:  ConfigVersion,
+		BuildTime:      BuildTime,
+		GitCommit:      GitCommit,
+		GoVersion:      GoVersion,
+		BuildTimestamp: timestamp,
+	}
+}
+
+// String returns a human-readable version string
+func String() string {
+	return fmt.Sprintf("RedFlag Agent v%s (config v%s)", Version, ConfigVersion)
+}
+
+// FullString returns detailed version information
+func FullString() string {
+	info := GetInfo()
+	return fmt.Sprintf("RedFlag Agent v%s (config v%s)\n"+
+		"Built: %s\n"+
+		"Commit: %s\n"+
+		"Go: %s",
+		info.AgentVersion,
+		info.ConfigVersion,
+		info.BuildTime,
+		info.GitCommit,
+		info.GoVersion)
+}
+
+// CheckCompatible checks if the given config version is compatible with this agent
+func CheckCompatible(configVer string) error {
+	if configVer == "" {
+		return fmt.Errorf("config version is empty")
+	}
+
+	// For now, require exact match
+	// In the future, we may support backward/forward compatibility matrices
+	if configVer != ConfigVersion {
+		return fmt.Errorf("config version mismatch: agent expects v%s, config has v%s",
+			ConfigVersion, configVer)
+	}
+
+	return nil
+}
+
+// Valid checks if version information is properly set
+func Valid() bool {
+	return Version != "dev" && ConfigVersion != "dev"
+}