diff --git a/tests/test_regressions.py b/tests/test_regressions.py
index b28be9a3..82725429 100644
--- a/tests/test_regressions.py
+++ b/tests/test_regressions.py
@@ -938,9 +938,13 @@ def test_messages_js_supports_live_reasoning_and_tool_completion(cleanup_test_se
         "live reasoning SSE events must update the active Worklog Thinking Card text"
     assert "const liveThinkingText=_liveThinkingText();" in src, \
         "live reasoning SSE events must compute the current segment's Worklog Thinking Card text once"
-    assert "if(!_upsertAnchorReasoning(liveThinkingText))" in src, \
+    assert "const anchorReasoningFallback={};" in src, \
+        "live reasoning SSE events must capture the active anchor id for fallback"
+    assert "if(!_upsertAnchorReasoning(liveThinkingText, anchorReasoningFallback))" in src, \
         "live reasoning SSE events must prefer the anchor renderer before falling back"
-    assert "_updateLiveThinkingCard(liveThinkingText,{anchorRenderFallback:true,sessionId:activeSid,streamId})" in src, \
+    assert "_updateLiveThinkingCard(liveThinkingText,{" in src and "...anchorReasoningFallback" in src, \
+        "live reasoning SSE events must carry anchor identity into the fallback renderer"
+    assert "anchorRenderFallback:true" in src and "sessionId:activeSid" in src and "streamId" in src, \
         "live reasoning SSE events must keep the current segment's Worklog Thinking Card as fallback"
     assert "source.addEventListener('tool_complete'" in src or 'source.addEventListener("tool_complete"' in src, \
         "messages.js must listen for live tool completion SSE events"
diff --git a/tests/test_stable_assistant_turn_anchor_registry.py b/tests/test_stable_assistant_turn_anchor_registry.py
index bc03eb05..4566baf8 100644
--- a/tests/test_stable_assistant_turn_anchor_registry.py
+++ b/tests/test_stable_assistant_turn_anchor_registry.py
@@ -1307,8 +1307,13 @@ def test_slice6_live_shadow_feed_wires_anchor_scene_for_visible_order_handoff():
     reasoning_body = _event_listener_body(src, "reasoning")
     assert "_applyToAnchor" not in reasoning_body
     assert "const liveThinkingText=_liveThinkingText();" in reasoning_body
-    assert "if(!_upsertAnchorReasoning(liveThinkingText))" in reasoning_body
-    assert "_updateLiveThinkingCard(liveThinkingText,{anchorRenderFallback:true,sessionId:activeSid,streamId})" in reasoning_body
+    assert "const anchorReasoningFallback={};" in reasoning_body
+    assert "if(!_upsertAnchorReasoning(liveThinkingText, anchorReasoningFallback))" in reasoning_body
+    assert "_updateLiveThinkingCard(liveThinkingText,{" in reasoning_body
+    assert "...anchorReasoningFallback" in reasoning_body
+    assert "anchorRenderFallback:true" in reasoning_body
+    assert "sessionId:activeSid" in reasoning_body
+    assert "streamId" in reasoning_body
     assert "function _flushReasoningToAnchor()" in src
     assert "_upsertAnchorReasoning(reasoningText" in src
     assert "`live-reasoning:${streamId}:final`" in src
diff --git a/tests/test_ui_tool_call_cleanup.py b/tests/test_ui_tool_call_cleanup.py
index 00951191..fe889172 100644
--- a/tests/test_ui_tool_call_cleanup.py
+++ b/tests/test_ui_tool_call_cleanup.py
@@ -686,21 +686,23 @@ class TestToolCallGroupingStatic:
         assert "const liveThinkingText=_liveThinkingText();" in reasoning_fn, (
             "Reasoning SSE updates should cache the live thinking text before routing."
         )
-        assert "_upsertAnchorReasoning(liveThinkingText)" in reasoning_fn, (
+        primary_call = "_upsertAnchorReasoning(liveThinkingText, anchorReasoningFallback)"
+        assert primary_call in reasoning_fn, (
             "Anchor reasoning must remain the primary renderer path."
         )
-        fallback_call = "_updateLiveThinkingCard(liveThinkingText,{anchorRenderFallback:true,sessionId:activeSid,streamId})"
-        assert reasoning_fn.index("_upsertAnchorReasoning(liveThinkingText)") < reasoning_fn.index(
-            fallback_call
-        ), (
+        fallback_call = "_updateLiveThinkingCard(liveThinkingText,{"
+        assert reasoning_fn.index(primary_call) < reasoning_fn.index(fallback_call), (
             "The legacy thinking card should only run after anchor upsert fails."
         )
-        assert "if(!_upsertAnchorReasoning(liveThinkingText)){" in reasoning_fn, (
+        assert "if(!_upsertAnchorReasoning(liveThinkingText, anchorReasoningFallback)){" in reasoning_fn, (
             "The legacy thinking card should be a falsy-anchor fallback."
         )
         assert reasoning_fn.count(fallback_call) == 1, (
             "Reasoning SSE updates should call the live thinking card only in fallback."
         )
+        assert "...anchorReasoningFallback" in reasoning_fn, (
+            "The fallback renderer must receive the exact Anchor reasoning identity."
+        )
         assert "_updateLiveThinkingCard(" in render_live_thinking_fn, (
             "Inline parsed thinking still needs the live thinking card renderer."
         )