MultiPartitionsDefinition and BackfillPolicy.single_run() not giving correct partition set in backfill job

[mtofano]

What's the issue?

Hi there,

I have the following partitions definition:

version_partitions_definition = StaticPartitionsDefinition(["v04"])
gsm_partitions_definition = MultiPartitionsDefinition(
    {"version": version_partitions_definition, "trade_date": weekday_partitions_definition}
)

I have an asset defined as follows:

@asset(
    partitions_def=gsm_partitions_definition,
    backfill_policy=BackfillPolicy.single_run(),
    group_name="security_info",
    kinds=["parquet"],
)
def security_info_versioned_staging(context: AssetExecutionContext) -> None:
    ...

My job is defined as follows:

security_info_versioned_job = define_asset_job(
    name="security_info_versioned_job",
    selection=[security_info_versioned_staging, security_info_versioned_staging_hive, security_info_versioned],
    hooks=build_last_job_result_hooks(
        dagster_instance="dagster_qe", code_location="dagster_pigs"
    ),
)

I manually launched a backfill on 61 partitions in total:

When I print out the partition information available via the context I see this:

>>> print(context.partition_keys)
['2025-01-02|v04']
>>> print(context.partition_time_window)
TimeWindow(start=datetime.datetime(2025, 1, 2, 0, 0, tzinfo=datetime.timezone.utc), end=datetime.datetime(2025, 1, 3, 0, 0, tzinfo=datetime.timezone.utc))
>>> print(context.partition_key_range)
PartitionKeyRange(start='2025-01-02|v04', end='2025-01-02|v04')

I would expect this to give me the complete range of dates. I can see in the tags of the run that it is properly set there, but does not materialize into the context instance correctly:

Is this a bug, or am I setting something in correctly?

Dagster version

dagster, version 1.9.8

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