diff --git a/src/testium/__init__.py b/src/testium/__init__.py
index 30a7c84..daebb43 100755
--- a/src/testium/__init__.py
+++ b/src/testium/__init__.py
@@ -11,6 +11,16 @@ sys.path.append(os.path.abspath(ourpath.parent))
 import interpreter.utils.constants as cst
 
 def main():
+    # Force UTF-8 on stdout/stderr so the runner's output survives a legacy
+    # console code page (Windows cp1252 can't encode box-drawing/accented
+    # chars). Only the stream encoders change; the locale default used for
+    # config files is untouched.
+    for _stream in (sys.stdout, sys.stderr):
+        try:
+            _stream.reconfigure(encoding="utf-8")
+        except (AttributeError, ValueError):
+            pass  # no stdout (frozen GUI) or non-reconfigurable stream
+
     # Subcommand dispatch (must run *before* argparse so neither 'schema' nor
     # 'lsp' has to share the GUI/batch flag surface). The subcommands also
     # skip the multiprocessing 'spawn' setup which is only meaningful for the
diff --git a/src/testium/interpreter/test_report/report_export_html.py b/src/testium/interpreter/test_report/report_export_html.py
index 023ec58..bd4f9ce 100644
--- a/src/testium/interpreter/test_report/report_export_html.py
+++ b/src/testium/interpreter/test_report/report_export_html.py
@@ -14,7 +14,7 @@ class ReportExportHTML(rpe.ReportExport):
         self.prepareFile()
         self.create_base()
         self.process_tests()
-        with open(self._file_name, 'w') as f:
+        with open(self._file_name, 'w', encoding="utf-8") as f:
             f.write(lxml.html.tostring(self.root, pretty_print=True).decode())
 
     def testsIterate(self, row):
diff --git a/src/testium/interpreter/test_report/report_export_junit.py b/src/testium/interpreter/test_report/report_export_junit.py
index 5f61d91..b9cb007 100644
--- a/src/testium/interpreter/test_report/report_export_junit.py
+++ b/src/testium/interpreter/test_report/report_export_junit.py
@@ -20,7 +20,7 @@ class ReportExportJUnit(rpe.ReportExport):
 
         ts = TestSuite(repname, test_cases=self.test_cases,
                        hostname=tm.gd('host_ip'))
-        with open(self._file_name, 'w') as f:
+        with open(self._file_name, 'w', encoding="utf-8") as f:
             TestSuite.to_file(f, [ts])
 
     def testsIterate(self, row):
diff --git a/test/validation/items/jsonrpc/test.tum b/test/validation/items/jsonrpc/test.tum
index dfe0d60..0ea39de 100644
--- a/test/validation/items/jsonrpc/test.tum
+++ b/test/validation/items/jsonrpc/test.tum
@@ -20,7 +20,7 @@
             console_name: jrpces
             key: $(test)_PASS
             steps:
-                - writeln: python3 {{include_directory}}/jrpc_echo_server.py -c {{include_directory}}/jrpces.ini
+                - writeln: '"$(python_bin)" {{include_directory}}/jrpc_echo_server.py -c {{include_directory}}/jrpces.ini'
                 - read_until: {expected: ready, timeout: 5}
 
         - console:
diff --git a/test/validation/items/run/sub_fail.tum b/test/validation/items/run/sub_fail.tum
new file mode 100644
index 0000000..c86b417
--- /dev/null
+++ b/test/validation/items/run/sub_fail.tum
@@ -0,0 +1,7 @@
+main:
+    name: run sub-test (always fail)
+    steps:
+        - check:
+            name: fail
+            values:
+                - false
diff --git a/test/validation/items/run/sub_pass.tum b/test/validation/items/run/sub_pass.tum
new file mode 100644
index 0000000..072658f
--- /dev/null
+++ b/test/validation/items/run/sub_pass.tum
@@ -0,0 +1,7 @@
+main:
+    name: run sub-test (always pass)
+    steps:
+        - check:
+            name: pass
+            values:
+                - true
diff --git a/test/validation/post_execution.py b/test/validation/post_execution.py
index b0ae4df..bb86d4f 100644
--- a/test/validation/post_execution.py
+++ b/test/validation/post_execution.py
@@ -89,7 +89,7 @@ def exec():
         junit_report = report.replace(".sqlite", f"-{test}.xml")
         print(junit_report)
         _prepare_file_to_save(junit_report)
-        with open(junit_report, "w") as f:
+        with open(junit_report, "w", encoding="utf-8") as f:
             f.write(TestSuite.to_xml_string([ts]))
 
     # cleanup
diff --git a/test/validation/run.bat b/test/validation/run.bat
index f540504..33a1bf5 100644
--- a/test/validation/run.bat
+++ b/test/validation/run.bat
@@ -89,6 +89,13 @@ REM Reports are stamped with the mode so successive runs don't clobber each othe
 
 SET "TAIL=-b -d "python_bin=%VENV_PYTHON%" -d "validation_report_file=validation-%MODE%" -- "%SCRIPT_DIR%\main.tum"%EXTRA%"
 
+REM The report-exporter plugin (items\report_plugin) is a pip entry-point
+REM package. It must live in the *testium* environment, so it is installed into
+REM the source/wheel venvs below. A frozen PyInstaller binary cannot see
+REM externally-installed plugins, so report_plugin is expected to be skipped
+REM there (same as Linux pyinstaller mode).
+SET "FAKE_EXPORTER=%SCRIPT_DIR%\fake_exporter"
+
 REM ---------- per-mode launcher ----------------------------------------------
 
 echo -- validation mode: %MODE%
@@ -100,8 +107,25 @@ echo ERROR: unknown --mode '%MODE%'. Expected: source ^| wheel ^| pyinstaller.
 exit /b 1
 
 :MODE_SOURCE
-call "%PROJECT_DIR%\run.bat" %TAIL%
-exit /b %ERRORLEVEL%
+REM Run testium from src\ in a dedicated venv set up here. We do NOT delegate to
+REM the project's run.bat: that one launches the GUI and does not forward its
+REM arguments, so the suite would never run head-less.
+SET "TESTIUM_VENV=%PROJECT_DIR%\test\tmp\testium_venv"
+IF NOT EXIST "%TESTIUM_VENV%" (
+    echo Creating testium venv at %TESTIUM_VENV%
+    %PYTHON_EXE% -m venv "%TESTIUM_VENV%"
+    IF !ERRORLEVEL! NEQ 0 (
+        echo ERROR while creating the testium venv.
+        exit /b 1
+    )
+    call "%TESTIUM_VENV%\Scripts\pip" install --quiet --upgrade pip
+    call "%TESTIUM_VENV%\Scripts\pip" install --quiet -r "%PROJECT_DIR%\src\requirements.txt"
+    REM language-server extra so `testium lsp` works from source (lsp_check.py)
+    call "%TESTIUM_VENV%\Scripts\pip" install --quiet "pygls>=1.3"
+)
+call "%TESTIUM_VENV%\Scripts\pip" install --quiet -e "%FAKE_EXPORTER%"
+SET CMD="%TESTIUM_VENV%\Scripts\python.exe" "%PROJECT_DIR%\src\testium"
+GOTO LAUNCH
 
 :MODE_WHEEL
 SET "WHEEL=%PROJECT_DIR%\dist\testium-%VERSION%-py3-none-any.whl"
@@ -115,10 +139,13 @@ IF NOT EXIST "%WHEEL_VENV%" (
     echo Creating wheel venv at %WHEEL_VENV%
     %PYTHON_EXE% -m venv --system-site-packages "%WHEEL_VENV%"
     call "%WHEEL_VENV%\Scripts\pip" install --quiet --upgrade pip
-    call "%WHEEL_VENV%\Scripts\pip" install --quiet "%WHEEL%"
+    REM install with the [lsp] extra so the wheel channel is validated in its
+    REM language-server-capable form (pulls pygls), matching `pip install testium[lsp]`.
+    call "%WHEEL_VENV%\Scripts\pip" install --quiet "%WHEEL%[lsp]"
 )
-"%WHEEL_VENV%\Scripts\python.exe" -m testium %TAIL%
-exit /b %ERRORLEVEL%
+call "%WHEEL_VENV%\Scripts\pip" install --quiet -e "%FAKE_EXPORTER%"
+SET CMD="%WHEEL_VENV%\Scripts\python.exe" -m testium
+GOTO LAUNCH
 
 :MODE_PYI
 SET "PYI_BIN=%PROJECT_DIR%\dist\testium-%VERSION%.exe"
@@ -127,5 +154,22 @@ IF NOT EXIST "%PYI_BIN%" (
     echo ERROR: PyInstaller binary not found in %PROJECT_DIR%\dist -- run build_all.sh first.
     exit /b 1
 )
-"%PYI_BIN%" %TAIL%
+SET CMD="%PYI_BIN%"
+GOTO LAUNCH
+
+REM ---------- launch ----------------------------------------------------------
+
+:LAUNCH
+echo -- launch: %CMD%
+
+REM LSP check (this exact channel): `schema` must keep its nested actions and
+REM `lsp` must answer initialize. Mirrors run.sh; aborts the run on failure.
+echo -- LSP check (%MODE%)
+"%VENV_PYTHON%" "%SCRIPT_DIR%\lsp_check.py" %CMD%
+IF !ERRORLEVEL! NEQ 0 (
+    echo ERROR: LSP check failed for mode %MODE%.
+    exit /b 1
+)
+
+%CMD% %TAIL%
 exit /b %ERRORLEVEL%