diff --git a/dstack/dstack-attest/src/attestation.rs b/dstack/dstack-attest/src/attestation.rs
index 5fabb8176..14b1e036c 100644
--- a/dstack/dstack-attest/src/attestation.rs
+++ b/dstack/dstack-attest/src/attestation.rs
@@ -870,6 +870,40 @@ impl TdxAttestationExt for AttestationV1 {
 }
 
 impl AttestationV1 {
+    /// Convert a V1 dstack attestation back to the legacy SCALE schema.
+    ///
+    /// This is only lossless for the original dstack stack with V1 runtime
+    /// events. Pod payloads and newer event encodings must remain on the V1
+    /// msgpack wire format.
+    pub fn try_into_legacy(self) -> Result<Attestation> {
+        let Self {
+            platform, stack, ..
+        } = self;
+        let StackEvidence::Dstack {
+            report_data,
+            runtime_events,
+            config,
+        } = stack
+        else {
+            bail!("dstack-pod attestation cannot be represented by the legacy schema");
+        };
+        if runtime_events
+            .iter()
+            .any(|event| !matches!(event.version, EventLogVersion::V1))
+        {
+            bail!("non-V1 runtime events cannot be represented by the legacy schema");
+        }
+        Ok(Attestation {
+            quote: platform_into_legacy_quote(platform),
+            runtime_events,
+            report_data: report_data
+                .try_into()
+                .map_err(|_| anyhow!("stack.report_data must be 64 bytes"))?,
+            config,
+            report: (),
+        })
+    }
+
     /// Decode the VM config from the external or embedded config.
     pub fn decode_vm_config<'a>(&'a self, config: &'a str) -> Result<VmConfig> {
         decode_vm_config_with_fallback(config, self.stack.config())
@@ -2819,6 +2853,40 @@ mod tests {
         assert!(matches!(upgraded.stack, StackEvidence::Dstack { .. }));
     }
 
+    #[test]
+    fn v1_dstack_with_v1_events_converts_losslessly_to_legacy() {
+        let mut legacy = dummy_tdx_attestation([0x5a; 64]);
+        legacy.runtime_events.push(cc_eventlog::RuntimeEvent::new(
+            "legacy-event".into(),
+            vec![1, 2, 3],
+            cc_eventlog::EventLogVersion::V1,
+        ));
+        let converted = legacy.clone().into_v1().try_into_legacy().unwrap();
+        assert_eq!(converted.report_data, legacy.report_data);
+        assert_eq!(converted.runtime_events.len(), 1);
+        assert!(matches!(
+            converted.into_versioned(),
+            VersionedAttestation::V0 { .. }
+        ));
+    }
+
+    #[test]
+    fn v1_conversion_rejects_lossy_legacy_projection() {
+        let pod = dummy_tdx_attestation([0x5b; 64])
+            .into_v1()
+            .into_dstack_pod("payload".into());
+        assert!(pod.try_into_legacy().is_err());
+        let mut v2 = dummy_tdx_attestation([0x5c; 64]).into_v1();
+        if let StackEvidence::Dstack { runtime_events, .. } = &mut v2.stack {
+            runtime_events.push(cc_eventlog::RuntimeEvent::new(
+                "v2-event".into(),
+                vec![4, 5, 6],
+                cc_eventlog::EventLogVersion::V2,
+            ));
+        }
+        assert!(v2.try_into_legacy().is_err());
+    }
+
     #[test]
     fn versioned_v0_projects_to_v1() {
         let projected = dummy_tdx_attestation([5u8; 64]).into_versioned().into_v1();
diff --git a/dstack/guest-agent-simulator/src/main.rs b/dstack/guest-agent-simulator/src/main.rs
index 30456f3a0..e8974f8b0 100644
--- a/dstack/guest-agent-simulator/src/main.rs
+++ b/dstack/guest-agent-simulator/src/main.rs
@@ -181,10 +181,11 @@ mod tests {
     }
 
     #[test]
-    fn simulator_attest_response_uses_supplied_report_data() {
+    fn simulator_attest_response_preserves_legacy_wire_format() {
         let platform = load_fixture_platform();
         let report_data = [0x5a; 64];
         let response = platform.attest_response(report_data).unwrap();
+        assert_eq!(response.attestation.first(), Some(&0x00));
         let patched = VersionedAttestation::from_bytes(&response.attestation)
             .unwrap()
             .into_v1();
diff --git a/dstack/guest-agent-simulator/src/simulator.rs b/dstack/guest-agent-simulator/src/simulator.rs
index f7fc6a91b..c0288cc73 100644
--- a/dstack/guest-agent-simulator/src/simulator.rs
+++ b/dstack/guest-agent-simulator/src/simulator.rs
@@ -58,23 +58,24 @@ pub fn simulated_quote_response(
 }
 
 pub fn simulated_attest_response(
-    attestation: &VersionedAttestation,
+    source: &VersionedAttestation,
     report_data: [u8; 64],
     patch_report_data: bool,
     generator: Option<&TdxGenerator>,
 ) -> Result<AttestResponse> {
-    let mut attestation = prepare_attestation(
-        attestation,
-        report_data,
-        patch_report_data,
-        generator,
-        "attest",
-    )?;
+    let preserve_legacy = matches!(source, VersionedAttestation::V0 { .. });
+    let mut attestation =
+        prepare_attestation(source, report_data, patch_report_data, generator, "attest")?;
     if let Some(event_log) = attestation.platform.tdx_event_log_mut() {
         cc_eventlog::tdx::fill_v2_preimages(event_log);
     }
+    let attestation = if preserve_legacy {
+        attestation.try_into_legacy()?.into_versioned()
+    } else {
+        VersionedAttestation::V1 { attestation }
+    };
     Ok(AttestResponse {
-        attestation: VersionedAttestation::V1 { attestation }.to_bytes()?,
+        attestation: attestation.to_bytes()?,
     })
 }
 
@@ -83,19 +84,23 @@ pub fn simulated_info_attestation(attestation: &VersionedAttestation) -> Version
 }
 
 pub fn simulated_certificate_attestation(
-    attestation: &VersionedAttestation,
+    source: &VersionedAttestation,
     pubkey: &[u8],
     patch_report_data: bool,
     generator: Option<&TdxGenerator>,
 ) -> Result<VersionedAttestation> {
+    let preserve_legacy = matches!(source, VersionedAttestation::V0 { .. });
     let report_data = QuoteContentType::RaTlsCert.to_report_data(pubkey);
     let attestation = prepare_attestation(
-        attestation,
+        source,
         report_data,
         patch_report_data,
         generator,
         "certificate_attestation",
     )?;
+    if preserve_legacy {
+        return Ok(attestation.try_into_legacy()?.into_versioned());
+    }
     Ok(VersionedAttestation::V1 { attestation })
 }