fix: address copilot review on v1 digest encoding and v2 fallback

- pin v1 digest event_type encoding to little-endian (to_le_bytes)
  so the on-wire format is platform-independent. x86 (dstack's only
  target) produces identical bytes, so existing RTMR3 values and
  verifiers are unaffected. the 2024 spec called out to_ne_bytes
  explicitly, but a stable wire format should not depend on the
  host platform.
- fix the EventLogVersion::V2 doc comment in dstack-types: it listed
  event_type 134217730 (0x08000002), but v1 and v2 share the same
  event_type 134217729 (0x08000001). the version is distinguished by
  the EventLogVersion field / json version key, not event_type.
- replace canonical_event_json_v2's .unwrap_or_default() with
  .or_panic(). silently returning "" on serialization failure would
  produce sha384("") as the digest, which is both wrong and hard to
  debug. the input is a well-formed json!{} literal so serialization
  cannot actually fail; or_panic makes that invariant explicit without
  tripping the expect_used clippy lint.

Author: kvinwang

Cargo.lock

@@ -17,6 +17,7 @@ dstack-types.workspace = true
 ez-hash.workspace = true
 fs-err.workspace = true
 hex.workspace = true
+or-panic.workspace = true
 scale.workspace = true
 serde.workspace = true
 serde-human-bytes.workspace = true

cc-eventlog/Cargo.toml

@@ -5,6 +5,7 @@
 use anyhow::{Context, Result};
 use dstack_types::EventLogVersion;
 use fs_err as fs;
+use or_panic::ResultOrPanic;
 use scale::{Decode, Encode};
 use serde::{Deserialize, Serialize};
 use serde_human_bytes::base64;
@@ -128,7 +129,7 @@ impl RuntimeEvent {
         match self.version {
             EventLogVersion::V1 => {
                 let mut buf = Vec::with_capacity(4 + 1 + self.event.len() + 1 + self.payload.len());
-                buf.extend_from_slice(&DSTACK_RUNTIME_EVENT_TYPE.to_ne_bytes());
+                buf.extend_from_slice(&DSTACK_RUNTIME_EVENT_TYPE.to_le_bytes());
                 buf.push(b':');
                 buf.extend_from_slice(self.event.as_bytes());
                 buf.push(b':');
@@ -158,7 +159,7 @@ pub fn canonical_event_json_v2(event: &str, payload: &[u8]) -> String {
         "payload": hex::encode(payload),
         "version": 2,
     });
-    serde_jcs::to_string(&obj).unwrap_or_default()
+    serde_jcs::to_string(&obj).or_panic("canonical JSON serialization failed")
 }
 
 /// Replay event logs
@@ -188,7 +189,7 @@ mod tests {
         );
         let digest = event.digest::<Sha384>();
         let expected = Sha384::hash([
-            &DSTACK_RUNTIME_EVENT_TYPE.to_ne_bytes()[..],
+            &DSTACK_RUNTIME_EVENT_TYPE.to_le_bytes()[..],
             b":",
             b"app-id",
             b":",

cc-eventlog/src/runtime_events.rs

@@ -19,7 +19,7 @@ pub enum EventLogVersion {
     #[default]
     V1,
     /// JSON canonical digest (JCS RFC 8785):
-    /// `SHA({"event":"...","event_type":134217730,"payload":"hex..."})`
+    /// `SHA({"event":"...","event_type":134217729,"payload":"hex...","version":2})`
     V2,
 }