Merge MCP Feature Branch into dev

.envrc

@@ -6,3 +6,8 @@ for venv_dir in .venv .env venv env .venv* env* ENV; do
         break
     fi
 done
+
+# Include optional, local-only environment overrides
+if [ -f .env ]; then
+    dotenv
+fi

.github/workflows/testing.yml

@@ -108,7 +108,7 @@ jobs:
         run: |
           python -m pip install --upgrade pip wheel
           python -m pip install "setuptools<80.0.0"
-          find packages -name dash-*.whl -print -exec sh -c 'pip install "{}[dev,ci,testing]"' \;
+          find packages -name dash-*.whl -print -exec sh -c 'pip install "{}[dev,ci,testing,diskcache]"' \;
 
       - name: Install dash-renderer dependencies
         working-directory: dash/dash-renderer
@@ -122,6 +122,8 @@ jobs:
           echo "DISPLAY=:99" >> $GITHUB_ENV
 
       - name: Run lint
+        env:
+          PYLINT_EXTRA_ARGS: ${{ matrix.python-version == '3.8' && '--ignored-modules=mcp' || '' }}
         run: npm run lint
 
       - name: Run unit tests
@@ -229,7 +231,7 @@ jobs:
         run: |
           python -m pip install --upgrade pip wheel
           python -m pip install "setuptools<80.0.0"
-          find packages -name dash-*.whl -print -exec sh -c 'pip install "{}[ci,testing,dev]"' \;
+          find packages -name dash-*.whl -print -exec sh -c 'pip install "{}[ci,testing,dev,diskcache]"' \;
 
       - name: Build/Setup test components
         run: npm run setup-tests.py  # TODO build the packages and save them to packages/ in build job

.pylintrc

@@ -431,7 +431,7 @@ max-returns=6
 max-statements=50
 
 # Minimum number of public methods for a class (see R0903).
-min-public-methods=2
+min-public-methods=1
 
 
 [IMPORTS]

CHANGELOG.md

@@ -4,9 +4,30 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 
 ## [UNRELEASED]
 
-### Fixed
+## [4.3.0rc1] - Unreleased
+
+## Added
+- [#3796](https://github.com/plotly/dash/pull/3796) MCP: Add `configure_mcp_server()` to toggle which content the MCP server exposes (`include_layout`, `include_callbacks`, `include_clientside_callbacks`, `include_pages`, `expose_callback_docstrings`). Only the parameters explicitly passed are updated; omitted parameters retain their current value.
+
+## Changed
+- [#3796](https://github.com/plotly/dash/pull/3796) MCP: Remove the `mcp_expose_docstrings` `Dash()` constructor argument; callback docstring exposure is now controlled via `configure_mcp_server(expose_callback_docstrings=...)`.
+
+## Fixed
 - [#3805](https://github.com/plotly/dash/pull/3805) Fix FastAPI POST routes deadlock caused by middleware consuming request body. Fixes [#3801](https://github.com/plotly/dash/issues/3801).
 
+## [4.3.0rc0] - 2026-05-21
+
+## Added
+- [#3710](https://github.com/plotly/dash/pull/3710) MCP: Framework utilities, types for interacting with layout
+- [#3711](https://github.com/plotly/dash/pull/3711) MCP: `CallbackAdapter` for representing callback-related data in MCP-friendly format
+- [#3712](https://github.com/plotly/dash/pull/3712) MCP: `Resources` for exposing app layout, components, and pages
+- [#3731](https://github.com/plotly/dash/pull/3731) MCP: Expose callbacks as `Tools`
+- [#3747](https://github.com/plotly/dash/pull/3747) MCP: Support pattern-matching callbacks in Tools
+- [#3748](https://github.com/plotly/dash/pull/3748) MCP: Format callback results for LLM consumption (rendered graphs, markdown tables)
+- [#3749](https://github.com/plotly/dash/pull/3749) MCP: `get_dash_component` Tool and callback execution
+- [#3750](https://github.com/plotly/dash/pull/3750) MCP: Server routes, `mcp_enabled` function decorator, and Streamable HTTP transport
+- [#3766](https://github.com/plotly/dash/pull/3766) MCP: Support background callbacks in Tools
+
 ## [4.2.0] - 2026-06-01 - *The Freedom Update*
 
 This release marks a major milestone for Dash, bringing unprecedented flexibility to how you build and deploy your applications.

components/dash-core-components/package.json

@@ -27,7 +27,7 @@
     "build:js": "webpack --mode production",
     "build:backends": "dash-generate-components ./src/components dash_core_components -p package-info.json  && cp dash_core_components_base/** dash_core_components/ && dash-generate-components ./src/components dash_core_components -p package-info.json -k RangeSlider,Slider,Dropdown,RadioItems,Checklist,DatePickerSingle,DatePickerRange,Input,Link --r-prefix 'dcc' --r-suggests 'dash,dashHtmlComponents,jsonlite,plotly' --jl-prefix 'dcc' && black dash_core_components",
     "build": "run-s prepublishOnly build:js build:backends",
-    "postbuild": "es-check es2015 dash_core_components/*.js",
+    "postbuild": "es-check es2017 dash_core_components/*.js",
     "build:watch": "watch 'npm run build' src",
     "format": "run-s private::format.*",
     "lint": "run-s private::lint.*"
@@ -126,6 +126,6 @@
     "react-dom": "16 - 19"
   },
   "browserslist": [
-    "last 10 years and not dead"
+    "last 11 years and not dead"
   ]
 }

components/dash-table/package.json

@@ -119,6 +119,6 @@
     "npm": ">=6.1.0"
   },
   "browserslist": [
-    "last 10 years and not dead"
+    "last 11 years and not dead"
   ]
 }

dash/_callback.py

@@ -39,6 +39,7 @@
 
 from .background_callback.managers import BaseBackgroundCallbackManager
 from ._callback_context import context_value
+from .types import CallbackExecutionResponse
 from ._no_update import NoUpdate
 from . import _validate
 
@@ -85,6 +86,8 @@ def callback(
     hidden: Optional[bool] = None,
     websocket: Optional[bool] = False,
     persistent: Optional[bool] = False,
+    mcp_enabled: Optional[bool] = None,
+    mcp_expose_docstring: Optional[bool] = None,
     **_kwargs,
 ) -> Callable[[Callable[Params, ReturnVar]], Callable[Params, ReturnVar]]:
     """
@@ -242,6 +245,8 @@ def callback(
         hidden=hidden,
         websocket=websocket,
         persistent=persistent,
+        mcp_enabled=mcp_enabled,
+        mcp_expose_docstring=mcp_expose_docstring,
     )
 
     return cast(
@@ -295,6 +300,8 @@ def insert_callback(
     hidden=None,
     websocket=False,
     persistent=False,
+    mcp_enabled=None,
+    mcp_expose_docstring=None,
 ) -> str:
     if prevent_initial_call is None:
         prevent_initial_call = config_prevent_initial_callbacks
@@ -338,6 +345,8 @@ def insert_callback(
         "allow_dynamic_callbacks": dynamic_creator,
         "no_output": no_output,
         "websocket": websocket,
+        "mcp_enabled": mcp_enabled,
+        "mcp_expose_docstring": mcp_expose_docstring,
     }
     callback_list.append(callback_spec)
 
@@ -453,10 +462,13 @@ def _setup_background_callback(
     return to_json(data)
 
 
-def _progress_background_callback(response, callback_manager, background):
+def _progress_background_callback(
+    response, callback_manager, background, cache_key=None
+):
     progress_outputs = background.get("progress")
-    adapter = get_app().backend.request_adapter()
-    cache_key = adapter.args.get("cacheKey")
+    if cache_key is None:
+        adapter = get_app().backend.request_adapter()
+        cache_key = adapter.args.get("cacheKey")
 
     if progress_outputs:
         # Get the progress before the result as it would be erased after the results.
@@ -468,21 +480,38 @@ def _progress_background_callback(response, callback_manager, background):
 
 
 def _update_background_callback(
-    error_handler, callback_ctx, response, kwargs, background, multi
+    error_handler,
+    callback_ctx,
+    response,
+    kwargs,
+    background,
+    multi,
+    cache_key=None,
+    job_id=None,
 ):
     """Set up the background callback and manage jobs."""
     callback_manager = _get_callback_manager(kwargs, background)
 
-    adapter = get_app().backend.request_adapter()
-    cache_key = adapter.args.get("cacheKey") if adapter else None
-    job_id = adapter.args.get("job") if adapter else None
+    if cache_key is None or job_id is None:
+        adapter = get_app().backend.request_adapter()
+        cache_key = cache_key or (adapter.args.get("cacheKey") if adapter else None)
+        job_id = job_id or (adapter.args.get("job") if adapter else None)
 
-    _progress_background_callback(response, callback_manager, background)
+    _progress_background_callback(
+        response, callback_manager, background, cache_key=cache_key
+    )
 
     output_value = callback_manager.get_result(cache_key, job_id)
 
     return _handle_rest_background_callback(
-        output_value, callback_manager, response, error_handler, callback_ctx, multi
+        output_value,
+        callback_manager,
+        response,
+        error_handler,
+        callback_ctx,
+        multi,
+        cache_key=cache_key,
+        job_id=job_id,
     )
 
 
@@ -494,10 +523,13 @@ def _handle_rest_background_callback(
     callback_ctx,
     multi,
     has_update=False,
+    cache_key=None,
+    job_id=None,
 ):
-    adapter = get_app().backend.request_adapter()
-    cache_key = adapter.args.get("cacheKey") if adapter else None
-    job_id = adapter.args.get("job") if adapter else None
+    if cache_key is None or job_id is None:
+        adapter = get_app().backend.request_adapter()
+        cache_key = cache_key or (adapter.args.get("cacheKey") if adapter else None)
+        job_id = job_id or (adapter.args.get("job") if adapter else None)
     # Must get job_running after get_result since get_results terminates it.
     job_running = callback_manager.job_running(job_id)
     if not job_running and output_value is callback_manager.UNDEFINED:
@@ -546,7 +578,7 @@ def _prepare_response(
     output_value,
     output_spec,
     multi,
-    response,
+    response: CallbackExecutionResponse,
     callback_ctx,
     app,
     original_packages,
@@ -558,7 +590,7 @@ def _prepare_response(
     allow_dynamic_callbacks,
 ):
     """Prepare the response object based on the callback output."""
-    component_ids = collections.defaultdict(dict)
+    component_ids: dict = collections.defaultdict(dict)
 
     if has_output:
         if not multi:
@@ -677,6 +709,8 @@ def register_callback(
         hidden=_kwargs.get("hidden", None),
         websocket=_kwargs.get("websocket", False),
         persistent=_kwargs.get("persistent", False),
+        mcp_enabled=_kwargs.get("mcp_enabled", None),
+        mcp_expose_docstring=_kwargs.get("mcp_expose_docstring"),
     )
 
     # pylint: disable=too-many-locals
@@ -711,7 +745,7 @@ def add_context(*args, **kwargs):
                 args, kwargs, inputs_state_indices, has_output, insert_output
             )
 
-            response: dict = {"multi": True}  # type: ignore
+            response: CallbackExecutionResponse = {"multi": True}
             jsonResponse: Optional[str] = None
             try:
                 if background is not None:
@@ -783,7 +817,7 @@ async def async_add_context(*args, **kwargs):
                 args, kwargs, inputs_state_indices, has_output, insert_output
             )
 
-            response = {"multi": True}
+            response: CallbackExecutionResponse = {"multi": True}
 
             try:
                 if background is not None:

dash/_configs.py

@@ -33,6 +33,8 @@ def load_dash_env_vars():
                 "DASH_DISABLE_VERSION_CHECK",
                 "DASH_PRUNE_ERRORS",
                 "DASH_COMPRESS",
+                "DASH_MCP_ENABLED",
+                "DASH_MCP_PATH",
                 "HOST",
                 "PORT",
             )