diff --git a/backend/secretapi/app.go b/backend/secretapi/app.go
index 7788b2b..6fa98b9 100644
--- a/backend/secretapi/app.go
+++ b/backend/secretapi/app.go
@@ -1827,9 +1827,11 @@ func writeErrorCode(w http.ResponseWriter, status int, code string, message stri
 		correlationID = "req_" + rid
 	}
 	normalizedCode := strings.TrimSpace(strings.ToLower(code))
+	canonicalCode := canonicalErrorCode(normalizedCode)
 	writeJSON(w, status, map[string]string{
 		"error":          message,
 		"code":           normalizedCode,
+		"canonical_code": canonicalCode,
 		"next_step":      errorNextStepForCode(normalizedCode),
 		"correlation_id": correlationID,
 	})
@@ -1867,6 +1869,20 @@ func errorNextStepForCode(code string) string {
 	}
 }
 
+func canonicalErrorCode(code string) string {
+	code = strings.TrimSpace(strings.ToLower(code))
+	switch code {
+	case "membership_inactive":
+		return "edut_id_inactive"
+	case "membership_required":
+		return "edut_id_required"
+	case "membership_verification_failed":
+		return "edut_id_verification_failed"
+	default:
+		return code
+	}
+}
+
 func appendUniqueString(existing []string, value string) []string {
 	value = strings.TrimSpace(value)
 	if value == "" {
diff --git a/docs/api/examples/governance-installer.examples.md b/docs/api/examples/governance-installer.examples.md
index c6ac43b..9f6ea52 100644
--- a/docs/api/examples/governance-installer.examples.md
+++ b/docs/api/examples/governance-installer.examples.md
@@ -110,6 +110,7 @@ Authorization: Bearer <wallet-session>
 {
   "error": "entitlement_inactive",
   "code": "entitlement_inactive",
+  "canonical_code": "entitlement_inactive",
   "correlation_id": "req_01J9B6BJBVKY3N6WQ7TQM2R2P5"
 }
 ```
diff --git a/docs/api/examples/member-channel.examples.md b/docs/api/examples/member-channel.examples.md
index fa4e304..025dc8a 100644
--- a/docs/api/examples/member-channel.examples.md
+++ b/docs/api/examples/member-channel.examples.md
@@ -107,6 +107,7 @@ Content-Type: application/json
 {
   "error": "membership_inactive",
   "code": "membership_inactive",
+  "canonical_code": "edut_id_inactive",
   "correlation_id": "req_01J9A4Q9GPDXDNZEWJ2FJS6F5R"
 }
 ```
@@ -145,6 +146,7 @@ Content-Type: application/json
 {
   "error": "contact_your_org_admin",
   "code": "owner_role_required",
+  "canonical_code": "owner_role_required",
   "correlation_id": "req_01J9A6ZC0SYF5A0M8AP8BNX7B2"
 }
 ```
@@ -155,6 +157,7 @@ Content-Type: application/json
 {
   "error": "owner support actions require onramp_attested identity assurance",
   "code": "identity_assurance_insufficient",
+  "canonical_code": "identity_assurance_insufficient",
   "correlation_id": "req_01J9A72Q2Q0VQ8MCR7D2N95D3R"
 }
 ```
diff --git a/docs/api/governance-installer.openapi.yaml b/docs/api/governance-installer.openapi.yaml
index 6c46ebc..a84a6f6 100644
--- a/docs/api/governance-installer.openapi.yaml
+++ b/docs/api/governance-installer.openapi.yaml
@@ -389,6 +389,10 @@ components:
           type: string
         code:
           type: string
+          description: Emitted compatibility code (may be legacy).
+        canonical_code:
+          type: string
+          description: Canonical EDUT ID era code alias for deterministic client routing.
         next_step:
           type: string
           description: Deterministic operator guidance for remediation/retry.
diff --git a/docs/api/member-channel.openapi.yaml b/docs/api/member-channel.openapi.yaml
index e25321a..e08ff62 100644
--- a/docs/api/member-channel.openapi.yaml
+++ b/docs/api/member-channel.openapi.yaml
@@ -413,6 +413,10 @@ components:
           type: string
         code:
           type: string
+          description: Emitted compatibility code (may be legacy).
+        canonical_code:
+          type: string
+          description: Canonical EDUT ID era code alias for deterministic client routing.
         next_step:
           type: string
           description: Deterministic operator guidance for remediation/retry.