diff --git a/README.md b/README.md
index 8eba50d..4c3a03a 100644
--- a/README.md
+++ b/README.md
@@ -63,9 +63,10 @@ agent_evidence:
 
 See [configuration](./docs/configuration.md) for more information.
 
-The agent adds `_agent_config_hash` to plugin and agent evidence labels. The value is a deterministic SHA-256 hash of
-the runtime plugin and agent evidence configuration, which prevents multiple unauthenticated agents using the fallback
-`_agent=ccf` identity from writing to the same evidence seed when their configurations differ.
+The agent sets the `_agent` label using the following fallback chain: `api.auth.client_id` when available, then
+`KUBERNETES_POD_NAME` or `KUBERNETES_POD`, and finally a deterministic SHA-256 hash of the runtime plugin and agent
+evidence configuration. This prevents multiple unauthenticated agents from writing to the same evidence seed when their
+configurations differ.
 
 ### Environment variables
 
diff --git a/cmd/agent.go b/cmd/agent.go
index 7b8eefe..31c54b7 100644
--- a/cmd/agent.go
+++ b/cmd/agent.go
@@ -200,7 +200,6 @@ const RunnerV2ProtocolVersion int32 = 2
 const AnnotationProtocolVersionKey = "org.ccf.plugin.protocol.version"
 const daemonCronStopTimeout = 30 * time.Second
 const agentEvidenceErrorArtifactMaxBytes = 1024 * 1024
-const agentConfigHashLabel = "_agent_config_hash"
 
 type pluginRunStatus string
 
@@ -836,15 +835,14 @@ func agentIdentityLabel(config *agentConfig) string {
 		}
 	}
 
-	return "ccf"
+	return agentConfigurationHash(config)
 }
 
 func agentFoundationalLabels(config *agentConfig) map[string]string {
 	return map[string]string{
-		"_agent":             agentIdentityLabel(config),
-		agentConfigHashLabel: agentConfigurationHash(config),
-		"tool":               "ccf",
-		"type":               "operations",
+		"_agent": agentIdentityLabel(config),
+		"tool":   "ccf",
+		"type":   "operations",
 	}
 }
 
@@ -962,7 +960,6 @@ func pluginEvidenceLabelsWithHash(config *agentConfig, pluginName string, plugin
 			labels[k] = v
 		}
 	}
-	labels[agentConfigHashLabel] = configHash
 	return labels
 }
 
diff --git a/cmd/agent_test.go b/cmd/agent_test.go
index 164043c..1520ed3 100644
--- a/cmd/agent_test.go
+++ b/cmd/agent_test.go
@@ -1301,10 +1301,9 @@ func TestAgentRunEvidenceIncludesPluginRunSummaryAndErrorArtifacts(t *testing.T)
 		t.Fatalf("expected readable failure reason, got %q", evidence.Status.Reason)
 	}
 	expectedLabels := map[string]string{
-		"_agent":             clientID,
-		agentConfigHashLabel: agentConfigurationHash(agentRunner.getConfig()),
-		"tool":               "ccf",
-		"type":               "operations",
+		"_agent": clientID,
+		"tool":   "ccf",
+		"type":   "operations",
 	}
 	for key, expected := range expectedLabels {
 		if evidence.Labels[key] != expected {
@@ -1654,14 +1653,13 @@ func TestSendAgentRunEvidenceAllowsNoPlugins(t *testing.T) {
 	if !ok {
 		t.Fatalf("expected labels object, got %#v", submitted["labels"])
 	}
-	if labels["_agent"] != "ccf" || labels["tool"] != "ccf" || labels["type"] != "operations" {
+	// When no client_id or pod env vars, _agent should be the config hash
+	expectedHash := agentConfigurationHash(agentRunner.getConfig())
+	if labels["_agent"] != expectedHash || labels["tool"] != "ccf" || labels["type"] != "operations" {
 		t.Fatalf("unexpected foundational labels: %#v", labels)
 	}
-	if labels[agentConfigHashLabel] != agentConfigurationHash(agentRunner.getConfig()) {
-		t.Fatalf("expected agent config hash label, got %#v", labels)
-	}
-	if len(labels) != 4 {
-		t.Fatalf("expected only four foundational labels, got %#v", labels)
+	if len(labels) != 3 {
+		t.Fatalf("expected only three foundational labels, got %#v", labels)
 	}
 	if _, ok := submitted["back-matter"]; ok {
 		t.Fatalf("expected no backmatter for passing no-plugin evidence, got %#v", submitted["back-matter"])
@@ -1722,6 +1720,17 @@ func TestAgentIdentityLabelFallsBackToKubernetesPodName(t *testing.T) {
 	if got != "123e4567-e89b-12d3-a456-426614174000" {
 		t.Fatalf("expected API auth client id to take precedence, got %q", got)
 	}
+
+	// Test that hash is final fallback when no client_id or pod name
+	t.Setenv("KUBERNETES_POD_NAME", "")
+	t.Setenv("KUBERNETES_POD", "")
+	config := newRuntimeHashTestConfig()
+	config.ApiConfig.Auth = nil // Remove client_id to test hash fallback
+	expectedHash := agentConfigurationHash(config)
+	got = agentIdentityLabel(config)
+	if got != expectedHash {
+		t.Fatalf("expected config hash as final fallback, got %q (expected %q)", got, expectedHash)
+	}
 }
 
 func TestAgentConfigurationHashUsesRuntimeConfigOnly(t *testing.T) {
@@ -1807,24 +1816,28 @@ func TestAgentConfigurationHashUsesRuntimeConfigOnly(t *testing.T) {
 
 func TestAgentFoundationalLabelsIncludeAgentConfigurationHash(t *testing.T) {
 	config := newRuntimeHashTestConfig()
+	config.ApiConfig.Auth = nil // Remove client_id to test hash fallback
 
 	labels := agentFoundationalLabels(config)
 
-	if labels[agentConfigHashLabel] != agentConfigurationHash(config) {
-		t.Fatalf("expected foundational labels to include config hash, got %#v", labels)
+	if labels["_agent"] != agentConfigurationHash(config) {
+		t.Fatalf("expected _agent label to contain config hash when no client_id, got %#v", labels)
 	}
 }
 
 func TestAgentRunEvidenceUUIDUsesAgentConfigurationHash(t *testing.T) {
 	now := time.Date(2026, 5, 8, 12, 0, 0, 0, time.UTC)
+	firstConfig := newRuntimeHashTestConfig()
+	firstConfig.ApiConfig.Auth = nil // Remove client_id to test hash fallback
 	firstRunner := NewAgentRunner()
-	firstRunner.UpdateConfig(newRuntimeHashTestConfig())
+	firstRunner.UpdateConfig(firstConfig)
 	firstEvidence, err := firstRunner.buildAgentRunEvidence(now)
 	if err != nil {
 		t.Fatalf("build first agent run evidence: %v", err)
 	}
 
 	secondConfig := newRuntimeHashTestConfig()
+	secondConfig.ApiConfig.Auth = nil // Remove client_id to test hash fallback
 	secondConfig.Plugins["plugin-a"].Source = "ghcr.io/example/plugin-a:v2"
 	secondRunner := NewAgentRunner()
 	secondRunner.UpdateConfig(secondConfig)
@@ -1833,8 +1846,8 @@ func TestAgentRunEvidenceUUIDUsesAgentConfigurationHash(t *testing.T) {
 		t.Fatalf("build second agent run evidence: %v", err)
 	}
 
-	if firstEvidence.Labels[agentConfigHashLabel] == secondEvidence.Labels[agentConfigHashLabel] {
-		t.Fatalf("expected different config hash labels, got %q", firstEvidence.Labels[agentConfigHashLabel])
+	if firstEvidence.Labels["_agent"] == secondEvidence.Labels["_agent"] {
+		t.Fatalf("expected different _agent labels, got %q", firstEvidence.Labels["_agent"])
 	}
 	if firstEvidence.UUID == secondEvidence.UUID {
 		t.Fatalf("expected config hash change to alter agent evidence UUID %s", firstEvidence.UUID)
@@ -1843,11 +1856,12 @@ func TestAgentRunEvidenceUUIDUsesAgentConfigurationHash(t *testing.T) {
 
 func TestPluginEvidenceLabelsIncludeAgentConfigurationHash(t *testing.T) {
 	config := newRuntimeHashTestConfig()
+	config.ApiConfig.Auth = nil // Remove client_id to test hash fallback
 
 	labels := pluginEvidenceLabels(config, "plugin-a", config.Plugins["plugin-a"])
 
-	if labels[agentConfigHashLabel] != agentConfigurationHash(config) {
-		t.Fatalf("expected plugin labels to include config hash, got %#v", labels)
+	if labels["_agent"] != agentConfigurationHash(config) {
+		t.Fatalf("expected _agent label to contain config hash when no client_id, got %#v", labels)
 	}
 	if labels["_plugin"] != "plugin-a" {
 		t.Fatalf("expected plugin label, got %#v", labels)
@@ -1859,7 +1873,7 @@ func TestPluginEvidenceLabelsIncludeAgentConfigurationHash(t *testing.T) {
 
 func TestPluginEvidenceSubmissionIncludesAgentConfigurationHash(t *testing.T) {
 	config := newRuntimeHashTestConfig()
-	config.ApiConfig.Auth = nil
+	config.ApiConfig.Auth = nil // Remove client_id to test hash fallback
 	var submittedLabels map[string]string
 	client := newTestHTTPClient(func(r *http.Request) (*http.Response, error) {
 		if r.URL.Path != "/api/evidence" {
@@ -1902,8 +1916,8 @@ func TestPluginEvidenceSubmissionIncludesAgentConfigurationHash(t *testing.T) {
 		t.Fatalf("create evidence: %v", err)
 	}
 
-	if submittedLabels[agentConfigHashLabel] != agentConfigurationHash(config) {
-		t.Fatalf("expected submitted plugin evidence to include config hash, got %#v", submittedLabels)
+	if submittedLabels["_agent"] != agentConfigurationHash(config) {
+		t.Fatalf("expected submitted plugin evidence to include config hash in _agent, got %#v", submittedLabels)
 	}
 	if submittedLabels["_plugin"] != "plugin-a" || submittedLabels["team"] != "security" {
 		t.Fatalf("expected submitted plugin evidence to include plugin labels, got %#v", submittedLabels)
diff --git a/docs/configuration.md b/docs/configuration.md
index 4324cd3..2cca8cd 100644
--- a/docs/configuration.md
+++ b/docs/configuration.md
@@ -39,11 +39,11 @@ agent_evidence:
 The `plugin_identifier` is a unique identifier for the plugin, and is used to identify the plugin in the logs, you can
 name this whatever you like but it must be unique.
 
-The `labels` should uniquely identify this agent instance. The agent also sets the `_agent` label on plugin evidence
-using `api.auth.client_id` when available, then `KUBERNETES_POD_NAME` or `KUBERNETES_POD`, and finally `ccf`. The agent
-also sets `_agent_config_hash`, a deterministic hash of the runtime plugin and agent evidence configuration. Because
-evidence UUIDs are seeded from labels, changing either the agent identity or runtime configuration changes the evidence
-stream for plugin evidence.
+The `labels` should uniquely identify this agent instance. The agent sets the `_agent` label on plugin evidence using
+the following fallback chain: `api.auth.client_id` when available, then `KUBERNETES_POD_NAME` or `KUBERNETES_POD`, and
+finally a deterministic SHA-256 hash of the runtime plugin and agent evidence configuration. Because evidence UUIDs are
+seeded from labels, changing either the agent identity or runtime configuration changes the evidence stream for plugin
+evidence.
 
 The `plugin_source` is the path to the plugin binary that the agent will run. This can be a relative or absolute path or
 even a URL to a remote plugin.
@@ -64,11 +64,11 @@ is `satisfied`. A plugin remains in the `Plugins with errors` summary until it f
 Plugins that have never run are listed as pending. Failed plugin errors are attached as back-matter resources and linked
 from the evidence so they can be downloaded.
 
-Agent evidence uses these labels: `_agent`, `_agent_config_hash`, `tool`, and `type`. The `_agent` label uses
-`api.auth.client_id` when available, then `KUBERNETES_POD_NAME` or `KUBERNETES_POD`, and finally defaults to `ccf`. The
-`_agent_config_hash` label is a SHA-256 hash of plugin names, sources, protocol versions, schedules, policies, plugin
-config, plugin labels, and `agent_evidence` settings. It does not include API URL, API auth, or verbosity. The `tool`
-label is `ccf`; the `type` label is `operations`.
+Agent evidence uses these labels: `_agent`, `tool`, and `type`. The `_agent` label uses the following fallback chain:
+`api.auth.client_id` when available, then `KUBERNETES_POD_NAME` or `KUBERNETES_POD`, and finally a SHA-256 hash of
+plugin names, sources, protocol versions, schedules, policies, plugin config, plugin labels, and `agent_evidence`
+settings. The hash does not include API URL, API auth, or verbosity. The `tool` label is `ccf`; the `type` label is
+`operations`.
 
 If no plugins are configured, ccf-agent still emits passing agent evidence on the configured interval when running in
 daemon mode. In non-daemon mode, ccf-agent can emit agent evidence only once per invocation.