Add AI coding agent detection to User-Agent header

Detect when the Go SQL driver is invoked by an AI coding agent (e.g.
Claude Code, Cursor, Gemini CLI) by checking well-known environment
variables, and append `agent/<product>` to the User-Agent string.

This enables Databricks to understand how much driver usage originates
from AI coding agents. Detection only succeeds when exactly one agent
is detected to avoid ambiguous attribution.

Mirrors the approach in databricks/cli#4287.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Vikrant Puppala <vikrant.puppala@databricks.com>

Author: vikrantpuppala

internal/agent/agent.go

@@ -0,0 +1,66 @@
+// Package agent detects whether the Go SQL driver is being invoked by an AI
+// coding agent by checking for well-known environment variables that agents set
+// in their spawned shell processes.
+//
+// Detection only succeeds when exactly one agent environment variable is
+// present, to avoid ambiguous attribution when multiple agent environments
+// overlap.
+//
+// Adding a new agent requires only a new constant and a new entry in
+// knownAgents.
+//
+// References for each environment variable:
+//   - ANTIGRAVITY_AGENT: Closed source. Google Antigravity sets this variable.
+//   - CLAUDECODE: https://github.com/anthropics/claude-code (sets CLAUDECODE=1)
+//   - CLINE_ACTIVE: https://github.com/cline/cline (shipped in v3.24.0)
+//   - CODEX_CI: https://github.com/openai/codex (part of UNIFIED_EXEC_ENV array in codex-rs)
+//   - CURSOR_AGENT: Closed source. Referenced in a gist by johnlindquist.
+//   - GEMINI_CLI: https://google-gemini.github.io/gemini-cli/docs/tools/shell.html (sets GEMINI_CLI=1)
+//   - OPENCODE: https://github.com/opencode-ai/opencode (sets OPENCODE=1)
+package agent
+
+import "os"
+
+const (
+	Antigravity = "antigravity"
+	ClaudeCode  = "claude-code"
+	Cline       = "cline"
+	Codex       = "codex"
+	Cursor      = "cursor"
+	GeminiCLI   = "gemini-cli"
+	OpenCode    = "opencode"
+)
+
+var knownAgents = []struct {
+	envVar  string
+	product string
+}{
+	{"ANTIGRAVITY_AGENT", Antigravity},
+	{"CLAUDECODE", ClaudeCode},
+	{"CLINE_ACTIVE", Cline},
+	{"CODEX_CI", Codex},
+	{"CURSOR_AGENT", Cursor},
+	{"GEMINI_CLI", GeminiCLI},
+	{"OPENCODE", OpenCode},
+}
+
+// Detect returns the product string of the AI coding agent driving the current
+// process, or an empty string if no agent (or multiple agents) are detected.
+func Detect() string {
+	return detect(os.Getenv)
+}
+
+// detect is the internal implementation that accepts an env lookup function
+// for testability.
+func detect(getenv func(string) string) string {
+	var detected []string
+	for _, a := range knownAgents {
+		if getenv(a.envVar) != "" {
+			detected = append(detected, a.product)
+		}
+	}
+	if len(detected) == 1 {
+		return detected[0]
+	}
+	return ""
+}

internal/agent/agent_test.go

@@ -0,0 +1,71 @@
+package agent
+
+import (
+	"testing"
+)
+
+func envWith(vars map[string]string) func(string) string {
+	return func(key string) string {
+		return vars[key]
+	}
+}
+
+func TestDetectsSingleAgent(t *testing.T) {
+	cases := []struct {
+		envVar  string
+		product string
+	}{
+		{"ANTIGRAVITY_AGENT", Antigravity},
+		{"CLAUDECODE", ClaudeCode},
+		{"CLINE_ACTIVE", Cline},
+		{"CODEX_CI", Codex},
+		{"CURSOR_AGENT", Cursor},
+		{"GEMINI_CLI", GeminiCLI},
+		{"OPENCODE", OpenCode},
+	}
+	for _, tc := range cases {
+		t.Run(tc.product, func(t *testing.T) {
+			got := detect(envWith(map[string]string{tc.envVar: "1"}))
+			if got != tc.product {
+				t.Errorf("detect() = %q, want %q", got, tc.product)
+			}
+		})
+	}
+}
+
+func TestReturnsEmptyWhenNoAgent(t *testing.T) {
+	got := detect(envWith(map[string]string{}))
+	if got != "" {
+		t.Errorf("detect() = %q, want empty", got)
+	}
+}
+
+func TestReturnsEmptyWhenMultipleAgents(t *testing.T) {
+	got := detect(envWith(map[string]string{
+		"CLAUDECODE":   "1",
+		"CURSOR_AGENT": "1",
+	}))
+	if got != "" {
+		t.Errorf("detect() = %q, want empty", got)
+	}
+}
+
+func TestIgnoresEmptyValues(t *testing.T) {
+	got := detect(envWith(map[string]string{"CLAUDECODE": ""}))
+	if got != "" {
+		t.Errorf("detect() = %q, want empty", got)
+	}
+}
+
+func TestDetectUsesOsGetenv(t *testing.T) {
+	// Clear all known agent env vars, then set one
+	for _, a := range knownAgents {
+		t.Setenv(a.envVar, "")
+	}
+	t.Setenv("CLAUDECODE", "1")
+
+	got := Detect()
+	if got != ClaudeCode {
+		t.Errorf("Detect() = %q, want %q", got, ClaudeCode)
+	}
+}

internal/client/client.go

@@ -20,6 +20,7 @@ import (
 	"time"
 
 	dbsqlerr "github.com/databricks/databricks-sql-go/errors"
+	"github.com/databricks/databricks-sql-go/internal/agent"
 	dbsqlerrint "github.com/databricks/databricks-sql-go/internal/errors"
 
 	"github.com/apache/thrift/lib/go/thrift"
@@ -295,6 +296,9 @@ func InitThriftClient(cfg *config.Config, httpclient *http.Client) (*ThriftServi
 		if cfg.UserAgentEntry != "" {
 			userAgent = fmt.Sprintf("%s/%s (%s)", cfg.DriverName, cfg.DriverVersion, cfg.UserAgentEntry)
 		}
+		if agentProduct := agent.Detect(); agentProduct != "" {
+			userAgent = fmt.Sprintf("%s agent/%s", userAgent, agentProduct)
+		}
 		thriftHttpClient.SetHeader("User-Agent", userAgent)
 
 	default: