diff --git a/cmd/wfctl/plugin_compat_model.go b/cmd/wfctl/plugin_compat_model.go
index 0f3fad95..831915b6 100644
--- a/cmd/wfctl/plugin_compat_model.go
+++ b/cmd/wfctl/plugin_compat_model.go
@@ -11,6 +11,7 @@ import (
 	"slices"
 	"strings"
 
+	"golang.org/x/mod/module"
 	"golang.org/x/mod/semver"
 )
 
@@ -190,6 +191,20 @@ func canonicalStrictSemver(version, label string) (string, error) {
 	return version, nil
 }
 
+func CanonicalEvidenceEngineVersion(version string) (string, error) {
+	version = strings.TrimSpace(version)
+	if version == "" {
+		return "", fmt.Errorf("engine version is required")
+	}
+	if !strings.HasPrefix(version, "v") {
+		version = "v" + version
+	}
+	if (!strictSemverRe.MatchString(version) && !module.IsPseudoVersion(version)) || !semver.IsValid(version) {
+		return "", fmt.Errorf("engine version %q must be semver MAJOR.MINOR.PATCH or a Go pseudo-version, with optional leading v", strings.TrimPrefix(version, "v"))
+	}
+	return version, nil
+}
+
 func NormalizeSHA256Hex(value string) (string, error) {
 	value = strings.TrimSpace(value)
 	if len(value) != sha256.Size*2 {
@@ -210,12 +225,12 @@ func ValidateCompatibilityEvidence(ev PluginCompatibilityEvidence) (PluginCompat
 	if ev.Version, err = CanonicalPluginVersion(ev.Version); err != nil {
 		return ev, err
 	}
-	if ev.EngineVersion, err = CanonicalEngineVersion(ev.EngineVersion); err != nil {
+	if ev.EngineVersion, err = CanonicalEvidenceEngineVersion(ev.EngineVersion); err != nil {
 		return ev, err
 	}
 	if ev.WfctlVersion != "" {
 		ev.WfctlVersion = strings.TrimSpace(ev.WfctlVersion)
-		if canonical, err := CanonicalEngineVersion(ev.WfctlVersion); err == nil {
+		if canonical, err := CanonicalEvidenceEngineVersion(ev.WfctlVersion); err == nil {
 			ev.WfctlVersion = canonical
 		}
 	}
diff --git a/cmd/wfctl/plugin_compat_model_test.go b/cmd/wfctl/plugin_compat_model_test.go
index e42052ed..bddb96a0 100644
--- a/cmd/wfctl/plugin_compat_model_test.go
+++ b/cmd/wfctl/plugin_compat_model_test.go
@@ -18,7 +18,6 @@ func TestPluginCompatVersionCanonicalization(t *testing.T) {
 			t.Fatalf("CanonicalEngineVersion(%q) = %q, want v0.51.2", input, got)
 		}
 	}
-
 	got, err := CanonicalPluginVersion("1.2.3")
 	if err != nil {
 		t.Fatalf("CanonicalPluginVersion: %v", err)
@@ -34,6 +33,38 @@ func TestPluginCompatVersionRejectsInvalid(t *testing.T) {
 			t.Fatalf("CanonicalEngineVersion(%q) succeeded, want error", input)
 		}
 	}
+	if _, err := CanonicalPluginVersion("v1.2.3-0.20260511085732-8246535de8bd"); err == nil {
+		t.Fatalf("CanonicalPluginVersion accepted pseudo-version")
+	}
+}
+
+func TestPluginCompatEvidenceEngineVersionCanonicalization(t *testing.T) {
+	for _, input := range []string{
+		"0.51.2",
+		"v0.51.2",
+		"0.0.0-20260511085732-8246535de8bd",
+		"v0.0.0-20260511085732-8246535de8bd",
+		"v0.51.3-0.20260511085732-8246535de8bd",
+		"v0.51.3-pre.0.20260511085732-8246535de8bd",
+	} {
+		got, err := CanonicalEvidenceEngineVersion(input)
+		if err != nil {
+			t.Fatalf("CanonicalEvidenceEngineVersion(%q): %v", input, err)
+		}
+		if !strings.HasPrefix(got, "v") {
+			t.Fatalf("CanonicalEvidenceEngineVersion(%q) = %q, want leading v", input, got)
+		}
+	}
+}
+
+func TestPluginCompatResolverEngineVersionStaysReleaseComparable(t *testing.T) {
+	got, comparable := resolvePluginCompatEngineVersion("v0.51.3-0.20260511085732-8246535de8bd")
+	if comparable {
+		t.Fatalf("pseudo engine version comparable = true, got %q", got)
+	}
+	if got != "v0.0.0" {
+		t.Fatalf("pseudo engine fallback = %q, want v0.0.0", got)
+	}
 }
 
 func TestPluginCompatDigestOmitsEvidenceDigest(t *testing.T) {