tests: pin ink engine in _make_tui_argv npm-bootstrap tests (post-merge semantic fix)

Main's rewritten test_tui_npm_install.py tests call _make_tui_argv expecting
the Ink/npm flow unconditionally; with the dual-engine dispatch merged in,
_resolve_tui_engine() auto-selects opentui whenever ui-opentui/dist is built
in the repo, routing the call away from the path under test (first subprocess
became 'node --version' instead of 'npm run build'). Pin the engine to ink
via an autouse fixture, mirroring the existing pinning precedent in
test_tui_resume_flow.py.

tests/plugins/test_langfuse_plugin.py

@@ -171,6 +171,40 @@ class TestHooksInert:
         mod.on_post_tool_call(tool_name="read_file", args={}, result="ok", task_id="t", session_id="s")
 
 
+class TestPayloadSanitization:
+    def test_safe_value_redacts_base64_data_uri_instead_of_truncating(self):
+        sys.modules.pop("plugins.observability.langfuse", None)
+        import importlib
+        mod = importlib.import_module("plugins.observability.langfuse")
+
+        payload = "data:image/png;base64," + ("a" * 20000)
+        result = mod._safe_value(payload)
+
+        assert result == {
+            "type": "data_uri",
+            "media_type": "image/png",
+            "omitted": True,
+            "length": len(payload),
+        }
+
+    def test_serialize_messages_redacts_data_uri_parts(self):
+        sys.modules.pop("plugins.observability.langfuse", None)
+        import importlib
+        mod = importlib.import_module("plugins.observability.langfuse")
+
+        payload = "data:image/jpeg;base64," + ("b" * 20000)
+        serialized = mod._serialize_messages([
+            {"role": "user", "content": [{"type": "image_url", "image_url": {"url": payload}}]}
+        ])
+
+        assert serialized[0]["content"][0]["image_url"]["url"] == {
+            "type": "data_uri",
+            "media_type": "image/jpeg",
+            "omitted": True,
+            "length": len(payload),
+        }
+
+
 # ---------------------------------------------------------------------------
 # Placeholder-credential guard (#23823).
 #
@@ -704,3 +738,76 @@ class TestToolObservationKeying:
         assert ended["output"] == {"status": "done"}
         assert not state.tools
 
+
+class TestUsageFromSanitizedResponse:
+    """Regression: ``post_api_request`` delivers ``response`` as a sanitized
+    dict (no ``.usage`` attribute) plus a separate ``usage`` summary dict. The
+    post-call handler must read the ``usage`` dict instead of treating the dict
+    response as a usage-bearing object and dropping all token/cost data."""
+
+    def _setup(self, mod, monkeypatch):
+        # Active client so on_post_llm_call does not early-return.
+        monkeypatch.setattr(mod, "_get_langfuse", lambda: object())
+        observation = object()
+        state = mod.TraceState(trace_id="trace-1", root_ctx=None, root_span=None)
+        state.generations[mod._request_key(1)] = observation
+        monkeypatch.setitem(mod._TRACE_STATE, mod._trace_key("task-1", "session-1"), state)
+        captured = {}
+
+        def fake_end_observation(obs, *, output=None, metadata=None, usage_details=None, cost_details=None):
+            captured["usage_details"] = usage_details
+
+        monkeypatch.setattr(mod, "_end_observation", fake_end_observation)
+        return captured
+
+    def test_sanitized_dict_response_uses_usage_dict(self, monkeypatch):
+        sys.modules.pop("plugins.observability.langfuse", None)
+        mod = importlib.import_module("plugins.observability.langfuse")
+        captured = self._setup(mod, monkeypatch)
+
+        # A plain dict has no ``.usage`` attribute — mirrors post_api_request.
+        mod.on_post_llm_call(
+            task_id="task-1",
+            session_id="session-1",
+            api_call_count=1,
+            model="gemini-3-flash-preview",
+            response={"model": "gemini-3-flash-preview", "usage": {"input_tokens": 100, "output_tokens": 20}},
+            usage={"input_tokens": 100, "output_tokens": 20},
+            assistant_content_chars=42,
+        )
+
+        # Before the fix the dict response shadowed the usage dict and tokens
+        # were lost (usage_details == {}).
+        assert captured["usage_details"] == {"input": 100, "output": 20}
+
+    def test_real_response_object_with_usage_still_used(self, monkeypatch):
+        sys.modules.pop("plugins.observability.langfuse", None)
+        mod = importlib.import_module("plugins.observability.langfuse")
+        captured = self._setup(mod, monkeypatch)
+
+        # A response object that genuinely carries usage must still take the
+        # response-object path (post_llm_call / legacy behavior).
+        seen = {}
+
+        def fake_usage_and_cost(resp, **_):
+            seen["resp"] = resp
+            return {"input": 7, "output": 3}, {}
+
+        monkeypatch.setattr(mod, "_usage_and_cost", fake_usage_and_cost)
+
+        class _Resp:
+            usage = {"prompt_tokens": 7, "completion_tokens": 3}
+
+        resp = _Resp()
+        mod.on_post_llm_call(
+            task_id="task-1",
+            session_id="session-1",
+            api_call_count=1,
+            model="gemini-3-flash-preview",
+            response=resp,
+            usage={"input_tokens": 999, "output_tokens": 999},
+            assistant_content_chars=42,
+        )
+
+        assert seen["resp"] is resp
+        assert captured["usage_details"] == {"input": 7, "output": 3}