fix(runner): retain unlabeled prefixes and complete tool JSON

Retain the published message identity when a provider begins labeling deltas. Preserve the original full-prefix oracle, separate subsequent message boundaries, and keep unknown JSON result fields inspectable. Record native, server and browser proof and the pending release gates.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

packages/paperclip-runner/docs/hermes.md

@@ -108,7 +108,10 @@ extend the task's execution deadline.
 - Assistant message identity v2 includes the provider message and provider turn.
   A final snapshot replaces only its own deltas, retaining preceding commentary
   and steered messages. Providers without message IDs retain the original
-  identity; existing PRP v1 events replay unchanged. This is an identity change
+  identity. If a provider first supplies an ID after an unlabelled prefix,
+  that prefix and the continuation retain one item identity and one final
+  snapshot. A later distinct native message gets its own item. Existing PRP v1
+  events replay unchanged. This is an identity change
   within the current event contract, not a new wire field or transcript rewrite.
 - Native questions publish a 65,536-character limit for text and custom
   answers. The form, canonical response validation and bridge count UTF-16

packages/paperclip-runner/runner/crates/runner-core/src/acpx_provider_state.rs

@@ -72,7 +72,7 @@ pub enum AcpxProviderStateEvent {
     SemanticResult(AcpxSemanticResult),
     AssistantMessage {
         turn_id: String,
-        message_id: Option<String>,
+        provider_item_id: Option<String>,
         text: String,
     },
     TurnTerminal {
@@ -110,6 +110,7 @@ pub struct AcpxProviderState {
     plan_revision: u64,
     assistant_text: String,
     assistant_message_id: Option<String>,
+    assistant_item_id: Option<String>,
     pi_assistant_message: Option<String>,
     pi_assistant_message_ids: BTreeSet<String>,
     pending_tools: BTreeMap<String, AcpxPendingTool>,
@@ -129,6 +130,7 @@ impl AcpxProviderState {
             plan_revision: 0,
             assistant_text: String::new(),
             assistant_message_id: None,
+            assistant_item_id: None,
             pi_assistant_message: None,
             pi_assistant_message_ids: BTreeSet::new(),
             pending_tools: BTreeMap::new(),
@@ -223,6 +225,7 @@ impl AcpxProviderState {
         self.plan_revision = 0;
         self.assistant_text.clear();
         self.assistant_message_id = None;
+        self.assistant_item_id = None;
         self.pi_assistant_message = None;
         self.pi_assistant_message_ids.clear();
         self.semantic_result = None;
@@ -389,13 +392,14 @@ impl AcpxProviderState {
                 if status == AcpxTurnStatus::Completed && !self.assistant_text.is_empty() {
                     events.push(AcpxProviderStateEvent::AssistantMessage {
                         turn_id: turn_id.clone(),
-                        message_id: self.assistant_message_id.take(),
+                        provider_item_id: self.assistant_item_id.take(),
                         text: std::mem::take(&mut self.assistant_text),
                     });
                 } else {
                     self.assistant_text.clear();
                 }
                 self.assistant_message_id = None;
+                self.assistant_item_id = None;
                 self.pi_assistant_message = None;
                 self.pi_assistant_message_ids.clear();
                 events.push(AcpxProviderStateEvent::TurnTerminal {
@@ -529,7 +533,7 @@ impl AcpxProviderState {
             let starts_new_message = provider_message_id.as_ref().is_some_and(|message_id| {
                 self.assistant_message_id
                     .as_ref()
-                    .is_none_or(|current| current != message_id)
+                    .is_some_and(|current| current != message_id)
             });
             let raw_text = payload
                 .get("text")
@@ -594,6 +598,7 @@ impl AcpxProviderState {
             // the task UI and can promote intermediate prose as final output.
             if starts_new_message || native_boundary_clears {
                 self.assistant_text.clear();
+                self.assistant_item_id = None;
             }
             if self
                 .assistant_text
@@ -662,7 +667,7 @@ impl AcpxProviderState {
             .as_deref()
             .expect("a decoded runtime event has a turn binding");
         let fallback_item_id = format!("acpx-event-{}", event.sequence);
-        let events = normalize_acpx_runtime_event(
+        let mut events = normalize_acpx_runtime_event(
             kind,
             &payload,
             tool_operation,
@@ -670,6 +675,26 @@ impl AcpxProviderState {
             turn_id,
             self.provider_requests,
         );
+        if kind == AcpxRuntimeEventKind::TextDelta
+            && payload.get("piMessageHistory").and_then(Value::as_bool) != Some(true)
+        {
+            // A provider can begin identifying a message after its first delta.
+            // Adopt that native ID for boundary detection, but retain the item's
+            // already-published identity so its prefix and final snapshot agree.
+            for activity in &mut events {
+                let item = activity
+                    .payload
+                    .as_object_mut()
+                    .expect("a normalized ACPX text delta is an object");
+                let item_id = item
+                    .get("itemId")
+                    .and_then(Value::as_str)
+                    .expect("a normalized ACPX text delta has an item identity")
+                    .to_owned();
+                let retained_id = self.assistant_item_id.get_or_insert(item_id);
+                item.insert("itemId".to_owned(), Value::String(retained_id.clone()));
+            }
+        }
         if let Some(revision) = next_plan_revision {
             self.plan_revision = revision;
         }

packages/paperclip-runner/runner/crates/runner-core/src/provider_events.rs

@@ -378,13 +378,10 @@ pub fn project_acpx_state_event(
         }
         AcpxProviderStateEvent::AssistantMessage {
             turn_id,
-            message_id,
+            provider_item_id,
             text,
         } => {
             require_projected_turn(context, turn_id)?;
-            let provider_item_id = message_id
-                .as_deref()
-                .map(|message_id| acpx_message_item_id(message_id, turn_id, "assistant-message"));
             one(
                 "item.completed",
                 EventPriority::P1,

packages/paperclip-runner/runner/crates/runner-core/tests/acpx_event_projection.rs

@@ -151,7 +151,7 @@ fn keeps_durable_correlation_separate_from_the_active_provider_turn() {
         &context,
         &AcpxProviderStateEvent::AssistantMessage {
             turn_id: "provider-turn-1".to_owned(),
-            message_id: None,
+            provider_item_id: None,
             text: "Done".to_owned(),
         },
     )
@@ -339,7 +339,7 @@ fn projects_assistant_terminal_and_diagnostic_events_fail_closed() {
 
     let assistant = project(AcpxProviderStateEvent::AssistantMessage {
         turn_id: "turn-1".to_owned(),
-        message_id: Some("opaque-provider-message".to_owned()),
+        provider_item_id: Some("opaque-provider-message".to_owned()),
         text: "Done".to_owned(),
     });
     assert_eq!(assistant[0].event_type, "item.completed");
@@ -629,7 +629,7 @@ fn runtime_request_projection_preserves_durable_identity_boundaries() {
 fn recovery_preserves_the_preceding_provider_turn_answer() {
     let first = project(AcpxProviderStateEvent::AssistantMessage {
         turn_id: "turn-1".to_owned(),
-        message_id: None,
+        provider_item_id: None,
         text: "Useful answer".to_owned(),
     });
     let mut recovery = context();
@@ -638,7 +638,7 @@ fn recovery_preserves_the_preceding_provider_turn_answer() {
         &recovery,
         &AcpxProviderStateEvent::AssistantMessage {
             turn_id: "recovery-turn".to_owned(),
-            message_id: None,
+            provider_item_id: None,
             text: "Recovery update".to_owned(),
         },
     )
@@ -673,6 +673,7 @@ fn assistant_message_identity_matches_its_snapshot_and_is_scoped_to_the_provider
             1,
         )
         .remove(0);
+        let provider_item_id = activity.payload["itemId"].as_str().unwrap().to_owned();
         let streamed = project(AcpxProviderStateEvent::Activity(activity.clone()));
         assert_eq!(
             streamed,
@@ -680,7 +681,7 @@ fn assistant_message_identity_matches_its_snapshot_and_is_scoped_to_the_provider
         );
         let final_message = project(AcpxProviderStateEvent::AssistantMessage {
             turn_id: "turn-1".to_owned(),
-            message_id: message_id.map(str::to_owned),
+            provider_item_id: Some(provider_item_id.clone()),
             text: "Done".to_owned(),
         });
         assert_eq!(
@@ -697,7 +698,7 @@ fn assistant_message_identity_matches_its_snapshot_and_is_scoped_to_the_provider
             &recovery,
             &AcpxProviderStateEvent::AssistantMessage {
                 turn_id: "recovery-turn".to_owned(),
-                message_id: message_id.map(str::to_owned),
+                provider_item_id: Some(provider_item_id.clone()),
                 text: "Recovered".to_owned(),
             },
         )

packages/paperclip-runner/runner/crates/runner-core/tests/acpx_provider_state.rs

@@ -70,8 +70,9 @@ fn accumulates_assistant_text_preserves_reasoning_and_flushes_before_terminal()
                 && event.payload["text"] == "Checking the result."
     ));
 
+    let mut assistant_item_id = None;
     for (sequence, text) in [(3, "Hello "), (4, "world")] {
-        state
+        let emitted = state
             .accept_event(&event(
                 sequence,
                 GeneratedAcpxSidecarEventType::RuntimeEvent,
@@ -79,6 +80,14 @@ fn accumulates_assistant_text_preserves_reasoning_and_flushes_before_terminal()
                 json!({"type":"text_delta","text":text}),
             ))
             .unwrap();
+        let AcpxProviderStateEvent::Activity(activity) = &emitted[0] else {
+            panic!("an assistant delta must emit progress");
+        };
+        let item_id = activity.payload["itemId"].as_str().unwrap().to_owned();
+        if let Some(retained) = &assistant_item_id {
+            assert_eq!(retained, &item_id);
+        }
+        assistant_item_id = Some(item_id);
     }
     let terminal = state
         .accept_event(&event(
@@ -90,8 +99,8 @@ fn accumulates_assistant_text_preserves_reasoning_and_flushes_before_terminal()
         .unwrap();
     assert!(matches!(
         &terminal[0],
-        AcpxProviderStateEvent::AssistantMessage { turn_id, message_id, text }
-            if turn_id == "turn-1" && message_id.is_none() && text == "Hello world"
+        AcpxProviderStateEvent::AssistantMessage { turn_id, provider_item_id, text }
+            if turn_id == "turn-1" && provider_item_id == &assistant_item_id && text == "Hello world"
     ));
     assert!(matches!(
         &terminal[1],
@@ -183,8 +192,8 @@ fn promotes_only_the_latest_provider_message_as_the_terminal_reply() {
         .unwrap();
     assert!(matches!(
         &terminal[0],
-        AcpxProviderStateEvent::AssistantMessage { message_id, text, .. }
-            if message_id.as_deref() == Some("message-2")
+        AcpxProviderStateEvent::AssistantMessage { provider_item_id, text, .. }
+            if provider_item_id.as_deref() == Some("message-2")
                 && text == "Second paragraph.\n\nStill final."
     ));
     let projected_final = project_acpx_state_event(&context, &terminal[0]).unwrap();
@@ -227,7 +236,7 @@ fn an_unlabelled_continuation_keeps_the_current_message_identity() {
             project_acpx_state_event(&context, &emitted[0]).unwrap()[0].payload["itemId"].clone(),
         );
     }
-    assert_ne!(ids[0], ids[1]);
+    assert_eq!(ids[0], ids[1]);
     assert_eq!(ids[1], ids[2]);
     let terminal = state
         .accept_event(&event(
@@ -239,7 +248,62 @@ fn an_unlabelled_continuation_keeps_the_current_message_identity() {
         .unwrap();
     let final_message = project_acpx_state_event(&context, &terminal[0]).unwrap();
     assert_eq!(final_message[0].payload["itemId"], ids[2]);
-    assert_eq!(final_message[0].payload["text"], "Hello world");
+    assert_eq!(
+        final_message[0].payload["text"],
+        "Unlabelled progress.Hello world"
+    );
+}
+
+#[test]
+fn an_identified_message_after_an_adopted_prefix_gets_its_own_item() {
+    let context = AcpxEventProjectionContext {
+        run_id: "run-1".to_owned(),
+        normalized_session_id: "session-1".to_owned(),
+        turn_id: "turn-1".to_owned(),
+        provider_turn_id: None,
+        item_id: "item-1".to_owned(),
+    };
+    let mut state = AcpxProviderState::new("run-1").unwrap();
+    state.begin_turn("turn-1").unwrap();
+    let mut ids = Vec::new();
+    for (sequence, payload) in [
+        (1, json!({"type":"text_delta","text":"Preface. "})),
+        (
+            2,
+            json!({"type":"text_delta","messageId":"first","text":"Progress."}),
+        ),
+        (
+            3,
+            json!({"type":"text_delta","messageId":"second","text":"Final "}),
+        ),
+        (4, json!({"type":"text_delta","text":"response."})),
+    ] {
+        let emitted = state
+            .accept_event(&event(
+                sequence,
+                GeneratedAcpxSidecarEventType::RuntimeEvent,
+                Some("turn-1"),
+                payload,
+            ))
+            .unwrap();
+        ids.push(
+            project_acpx_state_event(&context, &emitted[0]).unwrap()[0].payload["itemId"].clone(),
+        );
+    }
+    assert_eq!(ids[0], ids[1]);
+    assert_ne!(ids[1], ids[2]);
+    assert_eq!(ids[2], ids[3]);
+    let terminal = state
+        .accept_event(&event(
+            5,
+            GeneratedAcpxSidecarEventType::RuntimeTurnTerminal,
+            Some("turn-1"),
+            json!({"status":"completed"}),
+        ))
+        .unwrap();
+    let final_message = project_acpx_state_event(&context, &terminal[0]).unwrap();
+    assert_eq!(final_message[0].payload["itemId"], ids[3]);
+    assert_eq!(final_message[0].payload["text"], "Final response.");
 }
 
 #[test]
@@ -333,9 +397,16 @@ fn pi_native_boundary_order_and_terminal_completeness_fail_closed() {
 
 #[test]
 fn preserves_an_idless_prefix_when_the_provider_begins_identifying_deltas() {
+    let context = AcpxEventProjectionContext {
+        run_id: "run-1".to_owned(),
+        normalized_session_id: "session-1".to_owned(),
+        turn_id: "turn-1".to_owned(),
+        provider_turn_id: None,
+        item_id: "item-1".to_owned(),
+    };
     let mut state = AcpxProviderState::new("run-1").unwrap();
     state.begin_turn("turn-1").unwrap();
-    state
+    let prefix = state
         .accept_event(&event(
             1,
             GeneratedAcpxSidecarEventType::RuntimeEvent,
@@ -343,7 +414,7 @@ fn preserves_an_idless_prefix_when_the_provider_begins_identifying_deltas() {
             json!({"type":"text_delta","text":"Preface.\n\n"}),
         ))
         .unwrap();
-    state
+    let identified = state
         .accept_event(&event(
             2,
             GeneratedAcpxSidecarEventType::RuntimeEvent,
@@ -364,6 +435,14 @@ fn preserves_an_idless_prefix_when_the_provider_begins_identifying_deltas() {
         AcpxProviderStateEvent::AssistantMessage { text, .. }
             if text == "Preface.\n\nFinal response."
     ));
+    let prefix = project_acpx_state_event(&context, &prefix[0]).unwrap();
+    let identified = project_acpx_state_event(&context, &identified[0]).unwrap();
+    let final_message = project_acpx_state_event(&context, &terminal[0]).unwrap();
+    assert_eq!(prefix[0].payload["itemId"], identified[0].payload["itemId"]);
+    assert_eq!(
+        prefix[0].payload["itemId"],
+        final_message[0].payload["itemId"]
+    );
 }
 
 #[test]

packages/paperclip-runner/runner/crates/runner-core/tests/local_integrity_boundary_golden.rs

@@ -256,7 +256,7 @@ fn acpx_projection_matches_shared_plan_question_final_and_terminal_identity() {
             },
             &AcpxProviderStateEvent::AssistantMessage {
                 turn_id: context.turn_id.clone(),
-                message_id: None,
+                provider_item_id: None,
                 text: expected_final["text"]
                     .as_str()
                     .expect("final text")