diff --git a/agent/conversation_compression.py b/agent/conversation_compression.py
index 3bf4a23238..2cf2eaec0a 100644
--- a/agent/conversation_compression.py
+++ b/agent/conversation_compression.py
@@ -3040,14 +3040,19 @@ def _warn_summary_or_aux_fallback(agent: Any) -> None:
             )
 
 
-def _reset_read_dedup_caches(task_id: str, *, skills: bool = True) -> None:
+def _reset_read_dedup_caches(task_id: str, *, session_id: str = "", skills: bool = True) -> None:
     """Advance the file-read (and skill_view) repeat-read dedup to a fresh generation after a boundary.
     The mtime map is kept: the first read of each unchanged key returns full content compaction may have
     omitted; later reads return stubs, and stub-hit counters restart at the same boundary (#84857).
+    The computer_use screenshot dedup is session-keyed and forgets its last frame for the same reason.
     """
     with contextlib.suppress(Exception):
         from tools.file_tools_read_tracking import reset_file_dedup
         reset_file_dedup(task_id)
+    if session_id:
+        with contextlib.suppress(Exception):
+            from tools.computer_use.tool import reset_screenshot_dedup
+            reset_screenshot_dedup(session_id)
     if not skills:
         return
     with contextlib.suppress(Exception):
@@ -3145,7 +3150,7 @@ def _finish_compaction_boundary(
             )
         else:
             compressor._verify_compaction_cleared_threshold = True
-    _reset_read_dedup_caches(task_id)
+    _reset_read_dedup_caches(task_id, session_id=agent.session_id or "")
     return _compressed_est
 
 
@@ -3832,7 +3837,7 @@ def _compress_context_via_codex_app_server(
         # armed until a later turn; minimal test engines may lack update_from_response.
         if hasattr(agent.context_compressor, "update_from_response"):
             _record_codex_app_server_usage(agent, result, messages=messages)
-    _reset_read_dedup_caches(task_id, skills=False)
+    _reset_read_dedup_caches(task_id, session_id=agent.session_id or "", skills=False)
     logger.info(
         "codex app-server compaction done: session=%s thread=%s turn=%s", _sid,
         getattr(result, "thread_id", None) or "", getattr(result, "turn_id", None) or "",
diff --git a/tests/tools/test_computer_use_screenshot_dedup.py b/tests/tools/test_computer_use_screenshot_dedup.py
index 6ba0653c32..5fd9dcb557 100644
--- a/tests/tools/test_computer_use_screenshot_dedup.py
+++ b/tests/tools/test_computer_use_screenshot_dedup.py
@@ -145,3 +145,13 @@ class TestScreenshotDedup:
         cu_tool._capture_response(_cap(seed=1), session_id="s1")
         cu_tool.release_computer_use_session("s1")
         assert _is_multimodal(cu_tool._capture_response(_cap(seed=1), session_id="s1"))
+
+    def test_compaction_boundary_redelivers_pixels(self):
+        """The summary may have dropped the frame an "unchanged" note points at, so the first
+        capture after compaction must carry the image even when the screen is byte-identical."""
+        from agent.conversation_compression import _reset_read_dedup_caches
+
+        cu_tool._capture_response(_cap(seed=1), session_id="s1")
+        assert not _is_multimodal(cu_tool._capture_response(_cap(seed=1), session_id="s1"))
+        _reset_read_dedup_caches("task", session_id="s1")
+        assert _is_multimodal(cu_tool._capture_response(_cap(seed=1), session_id="s1"))
diff --git a/tools/computer_use/tool.py b/tools/computer_use/tool.py
index 58860cb996..f21239d3c3 100644
--- a/tools/computer_use/tool.py
+++ b/tools/computer_use/tool.py
@@ -116,13 +116,18 @@ def _screenshot_dedup_check(session_id: str, digest: str, target: Tuple[str, str
         return False
 
 def _reset_screenshot_dedup(session_id: Optional[str] = None) -> None:
-    """Forget dedup state (all sessions, or one)."""
+    """Forget dedup state (all sessions, or one scoped key)."""
     with _screenshot_dedup_lock:
         if session_id is None:
             _last_screenshot_state.clear()
         else:
             _last_screenshot_state.pop(session_id, None)
 
+def reset_screenshot_dedup(session_id: str) -> None:
+    """Compaction boundary hook (mirrors ``reset_file_dedup``): the summary may have dropped the frame an
+    "unchanged" note would point at, so the next capture of this session must deliver pixels again."""
+    _reset_screenshot_dedup(_scoped_sid(session_id))
+
 def _cua_permission_mode(session_id: str) -> str:
     """Map Hermes's approval bypass onto Cua's immutable mode; fails closed. Both identity namespaces are consulted
     (DB ``session_id`` and gateway ``session_key`` contextvar) or a gateway ``/yolo`` would be invisible here.