Add multiplier parameter to AverageRuntimeDeadline #63853

[haseebmalik18]

Add multiplier parameter to AverageRuntimeDeadline so users can set deadlines as a proportion of the average runtime instead of only a fixed interval.

closes: #63853

[Copilot]

Pull request overview

Adds a multiplier parameter to the AverageRuntimeDeadline reference so deadline computation can be proportional to historical average runtime (e.g., 1.5× average), not only “average + fixed interval”.

Changes:

• Add multiplier: float = 1.0 to AverageRuntime deadline references (SDK authoring, core evaluation, and serialized evaluation) and include it in (de)serialization.
• Apply the multiplier during runtime evaluation and expand logging to include scaled runtime.
• Add unit tests and documentation updates covering multiplier behavior and defaults.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
task-sdk/src/airflow/sdk/definitions/deadline.py	Adds multiplier to SDK reference object and serialization payload.
airflow-core/src/airflow/models/deadline.py	Applies multiplier in core runtime evaluation and includes it in (de)serialization.
airflow-core/src/airflow/serialization/definitions/deadline.py	Applies multiplier in serialized evaluation path and includes it in (de)serialization.
airflow-core/tests/unit/models/test_deadline.py	Adds tests for multiplier behavior, default behavior, and validation.
airflow-core/docs/howto/deadline-alerts.rst	Documents the new multiplier parameter and adds usage examples.