Fix XCom key handling when keys contain special characters like /

[Brunda10]

Closes : #55410
Summary

This PR fixes an issue where XCom keys containing special characters (for example /) would break API calls and cause 404 Not Found errors.

The problem happened because keys were passed directly in the URL without encoding, so FastAPI treated / as a path separator.

Changes Made

SDK (client.py, taskrunner.py)

• Keys are now URL-encoded (quoted) before sending them to the API.

APIs (core_api/routes/public/xcoms.py, execution_api/routes/xcoms.py)

• Keys from the URL are now decoded (unquoted) before looking them up in the database.

This PR ensures:

• Keys are always quoted when sent (safe for URLs).

• Keys are always unquoted when received (correct DB lookup).

• Aligns XCom behavior across different access points (UI, API, execution API, and task runner).

Testing:

from airflow.decorators import dag, task

@dag(schedule=None)
def xcom_slash():

    @task
    def this_works() -> dict[str, str]:
        return {"Some Key": "Some Value"}
    @task
    def this_works_as_well() -> str:
        return "/some/path/like/key"

    @task
    def this_does_not_work() -> dict[str, str]:
        return {"key with slash /": "Some Value"}

    this_works() >> this_works_as_well() >> this_does_not_work()

dag = xcom_slash() 

[ashb]

Needs unit tests adding please

[pierrejeambrun]

Just one nit but looks good to me.

We probably need a test for the public API too.

[pierrejeambrun]

I'm not sure to understand why this was updated.

[github-actions]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed in 5 days if no further activity occurs. Thank you for your contributions.

[henry3260]

Since this PR has become stale, I would like to help pick it up and get it merged.

[potiuk]

Closing this one in favour of #58344