fix: supress warnings for meta information in config in markdown

marimo/_ast/app_config.py

@@ -42,6 +42,11 @@ class _AppConfig:
     # The type of SQL output to display
     sql_output: SqlOutputType = "auto"
 
+    @staticmethod
+    def sanitize(updates: dict[str, Any]) -> dict[str, Any]:
+        """Return only recognized config keys, silently dropping others."""
+        return {k: v for k, v in updates.items() if hasattr(_AppConfig, k)}
+
     @staticmethod
     def from_untrusted_dict(
         updates: dict[str, Any], silent: bool = False

marimo/_ast/codegen.py

@@ -22,6 +22,7 @@
 from marimo._convert.converters import MarimoConvert
 from marimo._schemas.serialization import NotebookSerializationV1
 from marimo._types.ids import CellId_t
+from marimo._utils.marimo_path import MarimoPath
 from marimo._version import __version__
 
 if TYPE_CHECKING:
@@ -486,11 +487,14 @@ def generate_app_constructor(config: Optional[_AppConfig]) -> str:
 
 
 def generate_filecontents_from_ir(ir: NotebookSerializationV1) -> str:
+    # Markdown frontmatter may contain non-config metadata (e.g., author,
+    # description). Suppress warnings for unrecognized keys from markdown.
+    silent = MarimoPath(ir.filename).is_markdown() if ir.filename else False
     return generate_filecontents(
         codes=[cell.code for cell in ir.cells],
         names=[cell.name for cell in ir.cells],
         cell_configs=[CellConfig.from_dict(cell.options) for cell in ir.cells],
-        config=_AppConfig.from_untrusted_dict(ir.app.options),
+        config=_AppConfig.from_untrusted_dict(ir.app.options, silent=silent),
         header_comments=ir.header.value if ir.header else None,
     )
 

marimo/_ast/load.py

@@ -7,6 +7,7 @@
 
 from marimo import _loggers
 from marimo._ast.app import App, InternalApp
+from marimo._ast.app_config import _AppConfig
 from marimo._ast.parse import (
     MarimoFileError,
     NonMarimoPythonScriptError,
@@ -18,6 +19,7 @@
     UnparsableCell,
 )
 from marimo._session.notebook.serializer import get_notebook_serializer
+from marimo._utils.marimo_path import MarimoPath
 
 LOGGER = _loggers.marimo_logger()
 
@@ -80,7 +82,14 @@ def load_notebook_ir(
     # Use filepath from notebook if not explicitly provided
     if filepath is None:
         filepath = notebook.filename
-    app = App(**notebook.app.options, _filename=filepath)
+
+    # Markdown frontmatter may contain non-config metadata (e.g., author,
+    # description). Filter to only pass recognized config keys to App().
+    options = notebook.app.options
+    if filepath and MarimoPath(filepath).is_markdown():
+        options = _AppConfig.sanitize(options)
+
+    app = App(**options, _filename=filepath)
     for cell in notebook.cells:
         if isinstance(cell, UnparsableCell):
             app._unparsable_cell(cell.code, **cell.options)

marimo/_utils/variable_name.py

@@ -1,3 +1,4 @@
+# Copyright 2026 Marimo. All rights reserved.
 from __future__ import annotations
 
 import inspect

tests/_cli/test_cli.py

@@ -557,6 +557,46 @@ def test_cli_edit_new_file() -> None:
     _check_contents(p, b'"serverToken": ', contents)
 
 
+def test_cli_edit_markdown_no_config_warnings() -> None:
+    """Markdown frontmatter metadata should not produce config warnings.
+
+    Regression test for https://github.com/marimo-team/marimo/issues/8259
+    """
+    d = tempfile.TemporaryDirectory()
+    path = os.path.join(d.name, "notebook.md")
+    with open(path, "w") as f:
+        f.write(
+            "---\n"
+            "title: My Notebook\n"
+            "author: Test Author\n"
+            'description: "A test notebook"\n'
+            "---\n\n"
+            "```python {.marimo}\n"
+            "x = 1\n"
+            "```\n"
+        )
+
+    port = _get_port()
+    p = subprocess.Popen(
+        [
+            "marimo",
+            "edit",
+            path,
+            "-p",
+            str(port),
+            "--headless",
+            "--no-token",
+            "--skip-update-check",
+        ],
+        stderr=subprocess.PIPE,
+    )
+    contents = _try_fetch(port)
+    assert contents is not None
+    p.kill()
+    _, stderr = p.communicate(timeout=5)
+    assert b"Unrecognized key" not in stderr
+
+
 def test_cli_edit_with_additional_args(temp_marimo_file: str) -> None:
     port = _get_port()
     p = subprocess.Popen(