Improved static typing in dash.callback

[odorikakeru]

This PR improves static typing for the callback decorator by preserving wrapped function signatures in the callback decorator type contract.

Based on this conversation thread: [Feature Request] A "@dash.typed_callback" that plays more nicely with MyPy than "@dash.callback" #3691 - The decision was made to not implement @dash.typed_callback and instead update @dash.callback based on feedback.

Compliance tests added (not included in integration test directory as type hints don't affect run time behaviour).

DISCLOSURE: Testing code was written/edited with AI assistance.

Contributor Checklist

• I have broken down my PR scope into the following TODO tasks
  • Update callback decorator type signature
  • Add and validate callback decorator typing/runtime tests (some testing code written with AI assistance)
• I have run the tests locally and they passed. (refer to testing section in contributing)
• I have added tests, or extended existing tests, to cover any new features or bugs fixed in this PR

optionals

• I have added entry in the CHANGELOG.md
• If this PR needs a follow-up in dash docs, community thread, I have mentioned the relevant URLS as follows
  • this GitHub #PR number updates the dash docs
  • here is the show and tell thread in Plotly Dash community

[T4rk1n]

This is looking good.

The new typing test file is not running on ci, the command needs to be adapted here:

dash/.github/workflows/testing.yml

Line 139 in bf5a329

pytest tests/compliance/test_typing.py

Also need to run npm run format and fix the failing pylint:

************* Module dash._callback
dash/_callback.py:14:0: C0413: Import "import flask" should be placed at the top of the module (wrong-import-position)
dash/_callback.py:16:0: C0413: Import "from .dependencies import handle_callback_args, handle_grouped_callback_args, Output, ClientsideFunction, Input" should be placed at the top of the module (wrong-import-position)
dash/_callback.py:23:0: C0413: Import "from .development.base_component import ComponentRegistry" should be placed at the top of the module (wrong-import-position)
dash/_callback.py:24:0: C0413: Import "from .exceptions import InvalidCallbackReturnValue, PreventUpdate, WildcardInLongCallback, MissingLongCallbackManagerError, BackgroundCallbackError, ImportedInsideCallbackError" should be placed at the top of the module (wrong-import-position)
dash/_callback.py:33:0: C0413: Import "from ._grouping import flatten_grouping, make_grouping_by_index, grouping_len" should be placed at the top of the module (wrong-import-position)
dash/_callback.py:38:0: C0413: Import "from ._utils import create_callback_id, stringify_id, to_json, coerce_to_list, AttributeDict, clean_property_name" should be placed at the top of the module (wrong-import-position)
dash/_callback.py:47:0: C0413: Import "from . import _validate" should be placed at the top of the module (wrong-import-position)
dash/_callback.py:48:0: C0413: Import "from .background_callback.managers import BaseBackgroundCallbackManager" should be placed at the top of the module (wrong-import-position)
dash/_callback.py:49:0: C0413: Import "from ._callback_context import context_value" should be placed at the top of the module (wrong-import-position)
dash/_callback.py:50:0: C0413: Import "from ._no_update import NoUpdate" should be placed at the top of the module (wrong-import-position)

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