fix(analytics): detect AI agents from the variables that they set

cmd/analytics/analytics.go

@@ -4,6 +4,7 @@ import (
 	_ "embed"
 	"encoding/json"
 	"os"
+	"strings"
 
 	"github.com/launchdarkly/ldcli/cmd/cliflags"
 
@@ -30,26 +31,56 @@ func (osEnvChecker) StdoutFd() int            { return int(os.Stdout.Fd()) }
 //go:embed known_agents.json
 var knownAgentsJSON []byte
 
+// agentEnvVar maps an environment variable to an agent label. If Equals or
+// Contains is set, the value must also match. Otherwise any non-empty value
+// matches.
+// agentEnvVar maps an environment variable to an agent label. If Equals or
+// Contains is set, the value must also match. Otherwise any non-empty value
+// matches.
 type agentEnvVar struct {
-	EnvVar string `json:"env_var"`
+	EnvVar   string `json:"env_var"`
+	Equals   string `json:"equals,omitempty"`
+	Contains string `json:"contains,omitempty"`
+	Label    string `json:"label"`
+}
+
+func (a agentEnvVar) matches(value string) bool {
+	switch {
+	case value == "":
+		return false
+	case a.Equals != "":
+		return value == a.Equals
+	case a.Contains != "":
+		return strings.Contains(value, a.Contains)
+	default:
+		return true
+	}
+}
+
+// aiAgentPrefix maps the start of an AI_AGENT value to an agent label.
+type aiAgentPrefix struct {
+	Prefix string `json:"prefix"`
 	Label  string `json:"label"`
 }
 
 type knownAgentsConfig struct {
-	Agents    []agentEnvVar `json:"agents"`
-	CIEnvVars []string      `json:"ci_env_vars"`
+	AIAgentPrefixes []aiAgentPrefix `json:"ai_agent_prefixes"`
+	Agents          []agentEnvVar   `json:"agents"`
+	CIEnvVars       []string        `json:"ci_env_vars"`
 }
 
 var (
-	knownAgentEnvVars []agentEnvVar
-	knownCIEnvVars    []string
+	knownAIAgentPrefixes []aiAgentPrefix
+	knownAgentEnvVars    []agentEnvVar
+	knownCIEnvVars       []string
 )
 
 func init() {
 	var cfg knownAgentsConfig
 	if err := json.Unmarshal(knownAgentsJSON, &cfg); err != nil {
 		panic("failed to parse embedded known_agents.json: " + err.Error())
 	}
+	knownAIAgentPrefixes = cfg.AIAgentPrefixes
 	knownAgentEnvVars = cfg.Agents
 	knownCIEnvVars = cfg.CIEnvVars
 }
@@ -65,8 +96,12 @@ func detectAgentContext(env envChecker) string {
 		return "explicit:" + v
 	}
 
+	if label := aiAgentLabel(env.Getenv("AI_AGENT")); label != "" {
+		return label
+	}
+
 	for _, a := range knownAgentEnvVars {
-		if env.Getenv(a.EnvVar) != "" {
+		if a.matches(env.Getenv(a.EnvVar)) {
 			return a.Label
 		}
 	}
@@ -84,6 +119,61 @@ func detectAgentContext(env envChecker) string {
 	return "unknown-non-interactive"
 }
 
+// maxAIAgentNameLen limits the length of an unknown AI_AGENT name in a label.
+const maxAIAgentNameLen = 32
+
+// aiAgentLabel converts an AI_AGENT value to a label. AI_AGENT is a shared
+// convention: the value starts with the agent name and can have a version
+// after it, for example "claude-code_2-1-295_agent" or "devin@1". A known
+// name gets its label. An unknown name gets "ai-agent:<name>", without the
+// version. The function returns "" if the value has no usable name.
+func aiAgentLabel(value string) string {
+	value = strings.ToLower(strings.TrimSpace(value))
+	if value == "" {
+		return ""
+	}
+
+	for _, p := range knownAIAgentPrefixes {
+		if hasNamePrefix(value, p.Prefix) {
+			return p.Label
+		}
+	}
+
+	name, _, _ := strings.Cut(value, "@")
+	name, _, _ = strings.Cut(name, "_")
+	name = strings.Map(func(r rune) rune {
+		if (r >= 'a' && r <= 'z') || (r >= '0' && r <= '9') || r == '-' {
+			return r
+		}
+		return -1
+	}, name)
+	if len(name) > maxAIAgentNameLen {
+		name = name[:maxAIAgentNameLen]
+	}
+	if name == "" {
+		return ""
+	}
+
+	return "ai-agent:" + name
+}
+
+// hasNamePrefix reports whether value starts with prefix and the prefix ends at
+// a name boundary. For example, "amp" matches "amp" and "amp_1" but not "ampere".
+func hasNamePrefix(value, prefix string) bool {
+	if !strings.HasPrefix(value, prefix) {
+		return false
+	}
+	if len(value) == len(prefix) {
+		return true
+	}
+	switch value[len(prefix)] {
+	case '_', '@', '-':
+		return true
+	default:
+		return false
+	}
+}
+
 func CmdRunEventProperties(
 	cmd *cobra.Command,
 	name string,