diff --git a/pkg/services/api/ai_agent_provider.go b/pkg/services/api/ai_agent_provider.go
new file mode 100644
index 00000000..2aa66597
--- /dev/null
+++ b/pkg/services/api/ai_agent_provider.go
@@ -0,0 +1,136 @@
+package api
+
+import "strings"
+
+// AI agents are detected separately from automation (CI) environments because the two are
+// independent dimensions: an agent commonly runs inside a CI system or on an Octopus worker,
+// and both should be reported rather than one masking the other.
+
+// aiAgentEnvVar is the emerging cross-vendor convention for an agent to identify itself.
+// https://github.com/vercel/vercel/tree/main/packages/detect-agent
+const aiAgentEnvVar = "AI_AGENT"
+
+type aiAgentRule struct {
+	variable string
+	// value, when set, must match the variable's value (case-insensitive). When empty, any
+	// non-empty value matches.
+	value string
+}
+
+type aiAgent struct {
+	name  string
+	rules []aiAgentRule
+}
+
+// knownAIAgents is ordered: the first agent with a matching rule wins, so the result is
+// deterministic when several agents' variables are present (e.g. one agent running another).
+//
+// Variables that are commonly present without an agent driving the process are deliberately
+// excluded: CURSOR_TRACE_ID (any Cursor terminal), COPILOT_GITHUB_TOKEN and GOOSE_PROVIDER
+// (user configuration), REPL_ID (any Replit workspace) and ZED_TERM (any Zed terminal).
+//
+// References:
+// https://code.claude.com/docs/en/env-vars
+// https://source.dot.net/aspire/Telemetry/CodingAgentDetector.cs.html
+// https://docs.rs/is-ai-agent
+var knownAIAgents = []aiAgent{
+	{"ClaudeCode", []aiAgentRule{{variable: "CLAUDECODE"}, {variable: "CLAUDE_CODE_ENTRYPOINT"}}},
+	{"Cursor", []aiAgentRule{{variable: "CURSOR_AGENT"}, {variable: "CURSOR_EXTENSION_HOST_ROLE", value: "agent-exec"}}},
+	{"Codex", []aiAgentRule{{variable: "CODEX_SANDBOX"}, {variable: "CODEX_THREAD_ID"}, {variable: "CODEX_CI"}}},
+	{"GeminiCLI", []aiAgentRule{{variable: "GEMINI_CLI"}}},
+	{"GitHubCopilot", []aiAgentRule{{variable: "COPILOT_CLI"}, {variable: "COPILOT_AGENT"}, {variable: "GITHUB_COPILOT_CLI_MODE"}}},
+	{"OpenCode", []aiAgentRule{{variable: "OPENCODE", value: "1"}, {variable: "OPENCODE_CLIENT"}, {variable: "OPENCODE_AI"}}},
+	{"Antigravity", []aiAgentRule{{variable: "ANTIGRAVITY_AGENT"}}},
+	{"Goose", []aiAgentRule{{variable: "GOOSE_TERMINAL"}, {variable: "AGENT", value: "goose"}}},
+	{"Amp", []aiAgentRule{{variable: "AGENT", value: "amp"}}},
+	{"Cline", []aiAgentRule{{variable: "CLINE_ACTIVE"}, {variable: "CLINE_TASK_ID"}}},
+	{"RooCode", []aiAgentRule{{variable: "ROO_CODE_TASK_ID"}}},
+	{"Augment", []aiAgentRule{{variable: "AUGMENT_AGENT"}}},
+	{"QwenCode", []aiAgentRule{{variable: "QWEN_CODE"}}},
+	{"FactoryDroid", []aiAgentRule{{variable: "DROID_CLI"}}},
+	{"KimiCLI", []aiAgentRule{{variable: "KIMI_CLI"}}},
+	{"Trae", []aiAgentRule{{variable: "TRAE_AI_SHELL_ID"}}},
+	{"Aider", []aiAgentRule{{variable: "OR_APP_NAME", value: "Aider"}}},
+	{"OpenHands", []aiAgentRule{{variable: "OR_APP_NAME", value: "OpenHands"}}},
+}
+
+// aiAgentValuePrefixes maps the start of a normalised AI_AGENT value to a known agent name.
+// Vendors don't agree on a format (e.g. "claude-code_2-1-322_agent", "github_copilot_vscode_agent",
+// "devin@1"), so values are lowercased and runs of underscores and whitespace replaced with a single hyphen
+// before matching.
+var aiAgentValuePrefixes = []struct {
+	prefix string
+	name   string
+}{
+	{"claude-code", "ClaudeCode"},
+	{"cursor", "Cursor"},
+	{"codex", "Codex"},
+	{"gemini", "GeminiCLI"},
+	{"github-copilot", "GitHubCopilot"},
+	{"opencode", "OpenCode"},
+	{"antigravity", "Antigravity"},
+	{"goose", "Goose"},
+	{"amp", "Amp"},
+	{"cline", "Cline"},
+	{"augment", "Augment"},
+	{"devin", "Devin"},
+	{"replit", "Replit"},
+	{"v0", "V0"},
+}
+
+// GetAIAgent returns a user agent token naming the AI agent driving this process, or an empty
+// string when none is detected. Only a normalised name is reported: the raw AI_AGENT value is
+// free-form and user-settable, so it is used for matching and never included in the output.
+// Detection is based on self-reported environment variables, so it is suitable for analytics but
+// must not be relied on for security decisions.
+//
+// Examples:
+//
+//	AIAgent/ClaudeCode   AI_AGENT=claude-code_2-1-322_agent, or CLAUDECODE=1
+//	AIAgent/Cursor       CURSOR_AGENT=1
+//	AIAgent/Other        AI_AGENT set to a value that isn't recognised
+func GetAIAgent(e Environment) string {
+	aiAgentValue := strings.TrimSpace(e.Getenv(aiAgentEnvVar))
+
+	name := nameFromAIAgentValue(aiAgentValue)
+	if name == "" {
+		// Also covers an agent that sets AI_AGENT in a format that isn't recognised.
+		name = nameFromVendorVariables(e)
+	}
+	if name == "" && aiAgentValue != "" {
+		name = "Other"
+	}
+	if name == "" {
+		return ""
+	}
+
+	return "AIAgent/" + name
+}
+
+func nameFromVendorVariables(e Environment) string {
+	for _, agent := range knownAIAgents {
+		for _, rule := range agent.rules {
+			value := e.Getenv(rule.variable)
+			if value == "" {
+				continue
+			}
+			if rule.value == "" || strings.EqualFold(value, rule.value) {
+				return agent.name
+			}
+		}
+	}
+	return ""
+}
+
+func nameFromAIAgentValue(value string) string {
+	if value == "" {
+		return ""
+	}
+	normalised := strings.Join(strings.Fields(strings.ReplaceAll(strings.ToLower(value), "_", " ")), "-")
+	for _, p := range aiAgentValuePrefixes {
+		if strings.HasPrefix(normalised, p.prefix) {
+			return p.name
+		}
+	}
+	return ""
+}
diff --git a/pkg/services/api/ai_agent_provider_test.go b/pkg/services/api/ai_agent_provider_test.go
new file mode 100644
index 00000000..c6d59350
--- /dev/null
+++ b/pkg/services/api/ai_agent_provider_test.go
@@ -0,0 +1,149 @@
+package api_test
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/OctopusDeploy/go-octopusdeploy/v2/pkg/services/api"
+	"github.com/stretchr/testify/require"
+)
+
+func TestGetAIAgent_None(t *testing.T) {
+	e := api.NewMockEnvironment()
+	require.Equal(t, "", api.GetAIAgent(e))
+}
+
+func TestGetAIAgent_VendorVariables(t *testing.T) {
+	cases := []struct {
+		variable string
+		value    string
+		expected string
+	}{
+		{"CLAUDECODE", "1", "AIAgent/ClaudeCode"},
+		{"CLAUDE_CODE_ENTRYPOINT", "cli", "AIAgent/ClaudeCode"},
+		{"CURSOR_AGENT", "1", "AIAgent/Cursor"},
+		{"CURSOR_EXTENSION_HOST_ROLE", "agent-exec", "AIAgent/Cursor"},
+		{"CODEX_SANDBOX", "seatbelt", "AIAgent/Codex"},
+		{"CODEX_THREAD_ID", "abc", "AIAgent/Codex"},
+		{"GEMINI_CLI", "1", "AIAgent/GeminiCLI"},
+		{"COPILOT_CLI", "1", "AIAgent/GitHubCopilot"},
+		{"OPENCODE", "1", "AIAgent/OpenCode"},
+		{"OPENCODE_CLIENT", "cli", "AIAgent/OpenCode"},
+		{"ANTIGRAVITY_AGENT", "1", "AIAgent/Antigravity"},
+		{"GOOSE_TERMINAL", "1", "AIAgent/Goose"},
+		{"AGENT", "goose", "AIAgent/Goose"},
+		{"AGENT", "amp", "AIAgent/Amp"},
+		{"CLINE_ACTIVE", "true", "AIAgent/Cline"},
+		{"ROO_CODE_TASK_ID", "abc", "AIAgent/RooCode"},
+		{"AUGMENT_AGENT", "1", "AIAgent/Augment"},
+		{"QWEN_CODE", "1", "AIAgent/QwenCode"},
+		{"DROID_CLI", "1", "AIAgent/FactoryDroid"},
+		{"KIMI_CLI", "1", "AIAgent/KimiCLI"},
+		{"TRAE_AI_SHELL_ID", "abc", "AIAgent/Trae"},
+		{"OR_APP_NAME", "aider", "AIAgent/Aider"},
+		{"OR_APP_NAME", "OpenHands", "AIAgent/OpenHands"},
+	}
+
+	for _, c := range cases {
+		t.Run(c.variable+"="+c.value, func(t *testing.T) {
+			e := api.NewMockEnvironment()
+			e.Setenv(c.variable, c.value)
+			require.Equal(t, c.expected, api.GetAIAgent(e))
+		})
+	}
+}
+
+func TestGetAIAgent_ValueRulesRequireMatch(t *testing.T) {
+	cases := map[string]string{
+		"CURSOR_EXTENSION_HOST_ROLE": "user",
+		"OPENCODE":                   "0",
+		"AGENT":                      "teamcity-agent-01",
+		"OR_APP_NAME":                "SomethingElse",
+	}
+
+	for variable, value := range cases {
+		t.Run(variable, func(t *testing.T) {
+			e := api.NewMockEnvironment()
+			e.Setenv(variable, value)
+			require.Equal(t, "", api.GetAIAgent(e))
+		})
+	}
+}
+
+func TestGetAIAgent_ExcludesNoisyVariables(t *testing.T) {
+	for _, variable := range []string{"CURSOR_TRACE_ID", "COPILOT_GITHUB_TOKEN", "GOOSE_PROVIDER", "REPL_ID", "ZED_TERM"} {
+		t.Run(variable, func(t *testing.T) {
+			e := api.NewMockEnvironment()
+			e.Setenv(variable, "1")
+			require.Equal(t, "", api.GetAIAgent(e))
+		})
+	}
+}
+
+func TestGetAIAgent_IsDeterministicWhenAgentsAreNested(t *testing.T) {
+	e := api.NewMockEnvironment()
+	e.Setenv("CURSOR_AGENT", "1")
+	e.Setenv("CLAUDECODE", "1")
+	for i := 0; i < 50; i++ {
+		require.Equal(t, "AIAgent/ClaudeCode", api.GetAIAgent(e))
+	}
+}
+
+func TestGetAIAgent_AIAgentVariable(t *testing.T) {
+	cases := []struct {
+		value    string
+		expected string
+	}{
+		{"claude-code_2-1-322_agent", "AIAgent/ClaudeCode"},
+		{"claude-code", "AIAgent/ClaudeCode"},
+		{"Claude-Code", "AIAgent/ClaudeCode"},
+		{"Claude Code", "AIAgent/ClaudeCode"},
+		{"cursor-cli", "AIAgent/Cursor"},
+		{"github_copilot_vscode_agent", "AIAgent/GitHubCopilot"},
+		{"github-copilot-cli", "AIAgent/GitHubCopilot"},
+		{"devin@1", "AIAgent/Devin"},
+		{"custom-agent@2.0", "AIAgent/Other"},
+	}
+
+	for _, c := range cases {
+		t.Run(c.value, func(t *testing.T) {
+			e := api.NewMockEnvironment()
+			e.Setenv("AI_AGENT", c.value)
+			require.Equal(t, c.expected, api.GetAIAgent(e))
+		})
+	}
+}
+
+func TestGetAIAgent_AIAgentTakesPrecedenceOverVendorVariables(t *testing.T) {
+	e := api.NewMockEnvironment()
+	e.Setenv("CURSOR_AGENT", "1")
+	e.Setenv("AI_AGENT", "claude-code_2-1-322_agent")
+	require.Equal(t, "AIAgent/ClaudeCode", api.GetAIAgent(e))
+}
+
+func TestGetAIAgent_UnrecognisedAIAgentFallsBackToVendorName(t *testing.T) {
+	e := api.NewMockEnvironment()
+	e.Setenv("GEMINI_CLI", "1")
+	e.Setenv("AI_AGENT", "gcli")
+	require.Equal(t, "AIAgent/GeminiCLI", api.GetAIAgent(e))
+}
+
+func TestGetAIAgent_NeverIncludesRawAIAgentValue(t *testing.T) {
+	e := api.NewMockEnvironment()
+	e.Setenv("AI_AGENT", "  evil) agent\r\nX-Injected: 1 ")
+	require.Equal(t, "AIAgent/Other", api.GetAIAgent(e))
+
+	e.Setenv("AI_AGENT", strings.Repeat("a", 200))
+	require.Equal(t, "AIAgent/Other", api.GetAIAgent(e))
+
+	e.Setenv("AI_AGENT", " \t ")
+	require.Equal(t, "", api.GetAIAgent(e))
+}
+
+func TestGetAutomationEnvironment_IgnoresAIAgents(t *testing.T) {
+	e := api.NewMockEnvironment()
+	e.Setenv("CLAUDECODE", "1")
+	e.Setenv("GITHUB_ACTIONS", "true")
+	require.Equal(t, "GitHubActions", api.GetAutomationEnvironment(e))
+	require.Equal(t, "AIAgent/ClaudeCode", api.GetAIAgent(e))
+}
diff --git a/pkg/services/api/api.go b/pkg/services/api/api.go
index 856369b8..1e58a058 100644
--- a/pkg/services/api/api.go
+++ b/pkg/services/api/api.go
@@ -63,7 +63,11 @@ func GetUserAgentString(requestingTool string) string {
 		}
 	}
 
-	automationEnvironment := GetAutomationEnvironment(&OsEnvironment{})
+	environment := &OsEnvironment{}
+	automationEnvironment := GetAutomationEnvironment(environment)
+	if aiAgent := GetAIAgent(environment); aiAgent != "" {
+		automationEnvironment = automationEnvironment + " " + aiAgent
+	}
 
 	return strings.TrimSpace(fmt.Sprintf("%s/%s (%s; %s) go/%s %s %s", "go-octopusdeploy", version, runtime.GOOS, runtime.GOARCH, runtime.Version(), automationEnvironment, requestingTool))
 }