[#117]: Document and test MessageDisplay hook event compat (v2.1.152)

specs/01-parser-pipeline.md

@@ -129,14 +129,15 @@ flowchart TD
 
 ### Version-Compatibility Normalisations
 
-| Issue                                                                                     | Version      | Fix                                                                       |
-| ----------------------------------------------------------------------------------------- | ------------ | ------------------------------------------------------------------------- |
-| Tool inputs JSON-encoded as strings                                                       | pre-v2.1.92  | Deserialise inner string → object                                         |
-| Fork reference in `forkedFrom` field                                                      | pre-v2.1.118 | Map to synthetic `fork-context-ref`                                       |
-| Hook payload in content text                                                              | all          | Regex extraction of teammate ID, color, protocol                          |
-| Large outputs written to disk                                                             | v2.1.89+     | `RE_PERSISTED_OUTPUT_PATH` → file read                                    |
-| Dynamic Workflow lifecycle types                                                          | v2.1.154+    | Add to `NOISE_ENTRY_TYPES`; capture workflow fields on `Entry`            |
-| `cache_creation_input_tokens` always 0 when API uses nested `cache_creation.input_tokens` | v2.1.152+    | `cache_creation_from_value()` reads both flat and nested forms; takes max |
+| Issue                                                                                     | Version      | Fix                                                                                                                                              |
+| ----------------------------------------------------------------------------------------- | ------------ | ------------------------------------------------------------------------------------------------------------------------------------------------ |
+| Tool inputs JSON-encoded as strings                                                       | pre-v2.1.92  | Deserialise inner string → object                                                                                                                |
+| Fork reference in `forkedFrom` field                                                      | pre-v2.1.118 | Map to synthetic `fork-context-ref`                                                                                                              |
+| Hook payload in content text                                                              | all          | Regex extraction of teammate ID, color, protocol                                                                                                 |
+| Large outputs written to disk                                                             | v2.1.89+     | `RE_PERSISTED_OUTPUT_PATH` → file read                                                                                                           |
+| Dynamic Workflow lifecycle types                                                          | v2.1.154+    | Add to `NOISE_ENTRY_TYPES`; capture workflow fields on `Entry`                                                                                   |
+| `cache_creation_input_tokens` always 0 when API uses nested `cache_creation.input_tokens` | v2.1.152+    | `cache_creation_from_value()` reads both flat and nested forms; takes max                                                                        |
+| `MessageDisplay` hook event name                                                          | v2.1.152+    | `hook_event` stored as `String` — no enum; catch-all presence-of-hookEvent checks in classify handle any future event name without a code change |
 
 ---
 

src-tauri/src/parser/classify.rs

@@ -1709,6 +1709,96 @@ mod tests {
         }
     }
 
+    // --- Issue #117: v2.1.152+ MessageDisplay hook event is handled by existing catch-alls ---
+
+    #[test]
+    fn classify_message_display_progress_entry_produces_hook_msg() {
+        // v2.1.152+: MessageDisplay fires as a progress/hook_progress entry.
+        // The generic hookEvent presence check rescues it without an explicit match arm.
+        let e = Entry {
+            entry_type: "progress".to_string(),
+            uuid: "uuid-msg-display-progress".to_string(),
+            timestamp: "2026-05-27T10:00:00Z".to_string(),
+            data: Some(json!({
+                "type": "hook_progress",
+                "hookEvent": "MessageDisplay",
+                "hookName": "my-display-hook",
+                "command": "echo transforming"
+            })),
+            ..Default::default()
+        };
+        match classify(e) {
+            Some(ClassifiedMsg::Hook(h)) => {
+                assert_eq!(h.hook_event, "MessageDisplay");
+                assert_eq!(h.hook_name, "my-display-hook");
+            }
+            other => panic!(
+                "Expected Hook for MessageDisplay progress entry, got {:?}",
+                other
+            ),
+        }
+    }
+
+    #[test]
+    fn classify_message_display_system_hook_progress_entry_produces_hook_msg() {
+        // v2.1.152+: MessageDisplay may also arrive as type:"system", subtype:"hook_progress"
+        // in verbose/stream-json mode. The hook_progress subtype rescue must handle it.
+        let e = Entry {
+            entry_type: "system".to_string(),
+            uuid: "uuid-msg-display-sys".to_string(),
+            timestamp: "2026-05-27T10:01:00Z".to_string(),
+            subtype: "hook_progress".to_string(),
+            hook_event: "MessageDisplay".to_string(),
+            hook_name: "display-transform".to_string(),
+            ..Default::default()
+        };
+        match classify(e) {
+            Some(ClassifiedMsg::Hook(h)) => {
+                assert_eq!(h.hook_event, "MessageDisplay");
+                assert_eq!(h.hook_name, "display-transform");
+            }
+            other => panic!(
+                "Expected Hook for system/hook_progress MessageDisplay entry, got {:?}",
+                other
+            ),
+        }
+    }
+
+    #[test]
+    fn classify_message_display_attachment_entry_produces_hook_msg() {
+        // v2.1.152+: MessageDisplay hook results surface as attachment entries.
+        // The generic attachment hookEvent rescue must handle it without an explicit arm.
+        let e = Entry {
+            entry_type: "attachment".to_string(),
+            uuid: "uuid-msg-display-att".to_string(),
+            timestamp: "2026-05-27T10:02:00Z".to_string(),
+            attachment: Some(json!({
+                "type": "hook_success",
+                "hookEvent": "MessageDisplay",
+                "hookName": "my-display-hook",
+                "stdout": "transformed message text"
+            })),
+            ..Default::default()
+        };
+        match classify(e) {
+            Some(ClassifiedMsg::Hook(h)) => {
+                assert_eq!(h.hook_event, "MessageDisplay");
+                assert_eq!(h.hook_name, "my-display-hook");
+                let meta = h
+                    .metadata
+                    .expect("metadata must be captured for attachment hooks");
+                assert_eq!(
+                    meta.get("hookEvent").and_then(|v| v.as_str()),
+                    Some("MessageDisplay")
+                );
+            }
+            other => panic!(
+                "Expected Hook for MessageDisplay attachment entry, got {:?}",
+                other
+            ),
+        }
+    }
+
     // --- Issue #60: fork-context-ref entry (v2.1.118+) is silently dropped ---
 
     #[test]

src-tauri/src/parser/entry.rs

@@ -56,6 +56,10 @@ pub struct Entry {
     // Top-level fields present in system/hook_progress entries (verbose/stream-json mode).
     #[serde(default)]
     pub subtype: String,
+    // hook_event is stored as a plain String (not an enum) so that new hook event names
+    // introduced by future Claude Code releases (e.g. MessageDisplay added in v2.1.152) are
+    // captured as-is rather than rejected. Callers that need to distinguish specific event
+    // types should match on the string value with a wildcard fallback arm.
     #[serde(default, rename = "hookEvent")]
     pub hook_event: String,
     #[serde(default, rename = "hookName")]
@@ -1036,6 +1040,48 @@ mod tests {
         assert_eq!(entry.unwrap().uuid, "emoji-valid-pair");
     }
 
+    // --- Issue #117: v2.1.152+ MessageDisplay hook event compat ---
+
+    #[test]
+    fn parse_entry_captures_message_display_hook_event_as_string() {
+        // v2.1.152+: MessageDisplay is a new hook event name that surfaces in JSONL entries.
+        // hook_event is stored as a plain String so this new value is captured without rejection.
+        let line = json!({
+            "type": "system",
+            "subtype": "hook_progress",
+            "uuid": "msg-display-uuid-001",
+            "timestamp": "2026-05-27T10:00:00Z",
+            "hookEvent": "MessageDisplay",
+            "hookName": "my-display-hook"
+        });
+        let bytes = serde_json::to_vec(&line).unwrap();
+        let entry = parse_entry(&bytes).expect("must parse MessageDisplay hook entry");
+        assert_eq!(entry.hook_event, "MessageDisplay");
+        assert_eq!(entry.hook_name, "my-display-hook");
+    }
+
+    #[test]
+    fn parse_entry_message_display_as_attachment_is_captured() {
+        // MessageDisplay can also surface as an attachment entry (hook result).
+        let line = json!({
+            "type": "attachment",
+            "uuid": "msg-display-att-uuid",
+            "timestamp": "2026-05-27T11:00:00Z",
+            "attachment": {
+                "type": "hook_success",
+                "hookEvent": "MessageDisplay",
+                "hookName": "transform-hook"
+            }
+        });
+        let bytes = serde_json::to_vec(&line).unwrap();
+        let entry = parse_entry(&bytes).expect("must parse MessageDisplay attachment entry");
+        let att = entry.attachment.expect("attachment must be captured");
+        assert_eq!(
+            att.get("hookEvent").and_then(|v| v.as_str()),
+            Some("MessageDisplay")
+        );
+    }
+
     #[test]
     fn parse_entry_unknown_fields_are_silently_ignored() {
         // Future Claude Code versions may add more fields. The parser must never crash on

src-tauri/src/parser/session.rs

@@ -137,6 +137,13 @@ fn resolve_live_chain_uuids(entries: &[Entry]) -> HashSet<String> {
     // Step 3: walk backward from live_tip via parentUuid links.
     // When parentUuid is empty but logicalParentUuid is set (compact_boundary entries),
     // follow logicalParentUuid instead so that pre-compaction messages are included.
+    //
+    // UUID gap assumption (v2.1.152+): if a MessageDisplay hook hides an assistant message
+    // entirely, Claude Code may omit that entry from the JSONL, leaving a gap in the
+    // parentUuid chain. The `_ => break` arm below handles this gracefully — the backward
+    // walk simply terminates at the gap rather than panicking. The pre-gap messages are
+    // excluded from the live set, which is a conservative but safe degradation: they appear
+    // as a dead-end branch and are suppressed rather than shown in the wrong order.
     let mut live_set: HashSet<String> = HashSet::new();
     let mut current = live_tip;
     loop {