fix(chat): keep visible interim progress in timeline

CHANGELOG.md

@@ -3,6 +3,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Compact tool activity now keeps visible interim assistant progress in the live Session timeline instead of making that progress effectively collapsed-only inside Activity details. The interim assistant stream path creates and flushes a visible assistant segment before resetting for later tool/compression activity.
+
 ## [v0.51.137] — 2026-05-25 — Release DI (stage-batch19 — 6-PR medium-risk batch)
 
 ### Added

docs/UIUX-GUIDE.md

@@ -74,6 +74,11 @@ terse, for example `Activity: 4 tools`, and should not duplicate the thinking
 area, list every tool name in the summary, or add redundant trailing count
 badges.
 
+Visible interim assistant progress is part of the live conversation timeline,
+not raw debug detail. Compact Activity may collapse tool arguments, long tool
+results, and low-level reasoning detail, but it must not make concise
+user-visible progress text available only inside a collapsed disclosure.
+
 The existing two-stage proposal in `docs/ui-ux/two-stage-proposal.html` records a
 compatible direction for long turns: live work can be grouped as a worklog, then
 settled history can collapse while the final answer reads as the calm

docs/rfcs/webui-run-state-consistency-contract.md

@@ -82,6 +82,9 @@ while WebUI still has multiple overlapping state stores.
    browser-facing timeline renderer as live SSE events so recovery does not
    downgrade a structured Thinking / progress / tool / compression turn into a
    separate flattened presentation.
+   Visible interim assistant progress must remain visible timeline content; a
+   compact Activity disclosure may summarize adjacent tool/debug detail, but it
+   must not be the only place where the user can see emitted progress text.
 6. **Compression is not current intent.** Automatic compression summaries and
    reference cards are recovery/handoff material. They must not be treated as a
    new user request, active-turn content, or the default visible explanation for

static/messages.js

@@ -1352,9 +1352,10 @@ function attachLiveStream(activeSid, streamId, uploaded=[], options={}){
     };
     step();
   }
-  function _flushPendingSegmentRender(){
-    if(!assistantBody||!_renderPending) return;
-    _cancelAnimationFramePendingStreamRender();
+  function _flushPendingSegmentRender(options={}){
+    const force=!!(options&&options.force);
+    if(!assistantBody||(!force&&!_renderPending)) return;
+    if(_renderPending) _cancelAnimationFramePendingStreamRender();
     const displayText=segmentStart===0
       ? _parseStreamState().displayText
       : _stripXmlToolCalls(assistantText.slice(segmentStart));
@@ -1512,8 +1513,9 @@ function attachLiveStream(activeSid, streamId, uploaded=[], options={}){
         if(typeof updateThinking==='function') updateThinking(_liveThinkingText());
         else appendThinking(_liveThinkingText());
       }
-      _flushPendingSegmentRender();
       ensureAssistantRow(true);
+      _flushPendingSegmentRender({force:true});
+      if(typeof closeCurrentLiveActivityGroup==='function') closeCurrentLiveActivityGroup();
       _resetAssistantSegment();
       _scheduleRender();
     });

tests/test_issue2713_streaming_segment_flush.py

@@ -25,14 +25,14 @@ class TestFlushHelperExists:
 
     def test_flush_helper_declared(self):
         src = read("static/messages.js")
-        assert "function _flushPendingSegmentRender()" in src, (
+        assert "function _flushPendingSegmentRender(options={})" in src, (
             "_flushPendingSegmentRender helper must be declared in messages.js"
         )
 
     def test_flush_helper_guards_on_assistant_body(self):
         src = read("static/messages.js")
         m = re.search(
-            r"function _flushPendingSegmentRender\(\)\{.*?\n  \}",
+            r"function _flushPendingSegmentRender\(options=\{\}\)\{.*?\n  \}",
             src,
             re.DOTALL,
         )
@@ -45,7 +45,7 @@ class TestFlushHelperExists:
     def test_flush_helper_guards_on_render_pending(self):
         src = read("static/messages.js")
         m = re.search(
-            r"function _flushPendingSegmentRender\(\)\{.*?\n  \}",
+            r"function _flushPendingSegmentRender\(options=\{\}\)\{.*?\n  \}",
             src,
             re.DOTALL,
         )
@@ -58,7 +58,7 @@ class TestFlushHelperExists:
     def test_flush_helper_cancels_pending_raf(self):
         src = read("static/messages.js")
         m = re.search(
-            r"function _flushPendingSegmentRender\(\)\{.*?\n  \}",
+            r"function _flushPendingSegmentRender\(options=\{\}\)\{.*?\n  \}",
             src,
             re.DOTALL,
         )
@@ -71,7 +71,7 @@ class TestFlushHelperExists:
     def test_flush_helper_uses_smd_write(self):
         src = read("static/messages.js")
         m = re.search(
-            r"function _flushPendingSegmentRender\(\)\{.*?\n  \}",
+            r"function _flushPendingSegmentRender\(options=\{\}\)\{.*?\n  \}",
             src,
             re.DOTALL,
         )
@@ -84,7 +84,7 @@ class TestFlushHelperExists:
     def test_flush_helper_has_render_md_fallback(self):
         src = read("static/messages.js")
         m = re.search(
-            r"function _flushPendingSegmentRender\(\)\{.*?\n  \}",
+            r"function _flushPendingSegmentRender\(options=\{\}\)\{.*?\n  \}",
             src,
             re.DOTALL,
         )
@@ -97,7 +97,7 @@ class TestFlushHelperExists:
     def test_flush_helper_has_esc_fallback(self):
         src = read("static/messages.js")
         m = re.search(
-            r"function _flushPendingSegmentRender\(\)\{.*?\n  \}",
+            r"function _flushPendingSegmentRender\(options=\{\}\)\{.*?\n  \}",
             src,
             re.DOTALL,
         )
@@ -159,7 +159,7 @@ class TestInterimAssistantHandlerFlush:
     def test_interim_handler_calls_flush(self):
         src = read("static/messages.js")
         fn = _extract_handler(src, "interim_assistant")
-        assert "_flushPendingSegmentRender()" in fn, (
+        assert "_flushPendingSegmentRender({force:true})" in fn, (
             "interim_assistant handler must call _flushPendingSegmentRender() "
             "before _resetAssistantSegment()"
         )
@@ -169,10 +169,32 @@ class TestInterimAssistantHandlerFlush:
         the segment for new content (not the early alreadyStreamed branch)."""
         src = read("static/messages.js")
         fn = _extract_handler(src, "interim_assistant")
-        flush_pos = fn.index("_flushPendingSegmentRender()")
+        flush_pos = fn.index("_flushPendingSegmentRender({force:true})")
         # Find the _resetAssistantSegment call that comes AFTER the flush
         reset_pos = fn.index("_resetAssistantSegment()", flush_pos)
         assert flush_pos < reset_pos, (
             "_flushPendingSegmentRender must be called BEFORE the final "
             "_resetAssistantSegment in the interim_assistant handler"
         )
+
+    def test_interim_handler_creates_visible_segment_before_forced_flush(self):
+        src = read("static/messages.js")
+        fn = _extract_handler(src, "interim_assistant")
+        ensure_pos = fn.index("ensureAssistantRow(true)")
+        flush_pos = fn.index("_flushPendingSegmentRender({force:true})")
+        reset_pos = fn.index("_resetAssistantSegment()", flush_pos)
+        assert ensure_pos < flush_pos < reset_pos, (
+            "visible interim assistant progress must create a live assistant "
+            "segment, synchronously flush it, then reset for the next segment"
+        )
+
+    def test_interim_handler_closes_activity_after_visible_progress_boundary(self):
+        src = read("static/messages.js")
+        fn = _extract_handler(src, "interim_assistant")
+        flush_pos = fn.index("_flushPendingSegmentRender({force:true})")
+        close_pos = fn.index("closeCurrentLiveActivityGroup()", flush_pos)
+        reset_pos = fn.index("_resetAssistantSegment()", close_pos)
+        assert flush_pos < close_pos < reset_pos, (
+            "visible interim assistant progress is timeline content; it must "
+            "close the current live Activity burst before later tools append"
+        )

tests/test_ui_tool_call_cleanup.py

@@ -285,7 +285,7 @@ class TestToolCallGroupingStatic:
             "The non-simplified path should preserve standalone settled thinking cards."
         )
 
-    def test_live_visible_interim_text_keeps_single_activity_group(self):
+    def test_live_visible_interim_text_preserves_timeline_boundary(self):
         live_thinking_fn = _function_body(UI_JS, "appendThinking")
         live_tool_fn = _function_body(UI_JS, "appendLiveToolCard")
         helper = _function_body(UI_JS, "ensureActivityGroup")
@@ -318,12 +318,18 @@ class TestToolCallGroupingStatic:
             "Compact live thinking should reactivate the latest existing Thinking card instead of stacking a new card after every tool boundary."
         )
         reset_fn = _function_body(MESSAGES_JS, "_resetAssistantSegment")
-        assert "_closeCurrentLiveActivityGroup" not in MESSAGES_JS and "closeActivity" not in reset_fn, (
-            "Assistant text resets should not carry a dead Activity-splitting path."
+        assert "function closeCurrentLiveActivityGroup()" in UI_JS, (
+            "Visible interim assistant progress needs a shared helper to close the current Activity burst."
         )
         interim_match = re.search(r"source\.addEventListener\('interim_assistant',e=>\{(.*?)\n\s*\}\);", MESSAGES_JS, re.S)
-        assert interim_match and "_resetAssistantSegment({closeActivity:true});" not in interim_match.group(1), (
-            "Visible interim assistant text should not split Compact tool activity into multiple Activity rows."
+        assert interim_match and "closeCurrentLiveActivityGroup()" in interim_match.group(1), (
+            "Visible interim assistant progress is timeline content and must split the current Activity burst."
+        )
+        assert interim_match and "ensureAssistantRow(true)" in interim_match.group(1), (
+            "Visible interim assistant progress must create a visible assistant timeline segment."
+        )
+        assert interim_match and "_flushPendingSegmentRender({force:true})" in interim_match.group(1), (
+            "Visible interim assistant progress must be synchronously rendered before the segment reset."
         )
         tool_start_segment = MESSAGES_JS.split("source.addEventListener('tool',e=>{", 1)[1].split("source.addEventListener('tool_complete'", 1)[0]
         assert "_resetAssistantSegment();" in tool_start_segment, (