Previously, hooks used in API server contexts (plugins, middlewares, log handlers) would fail with an ImportError for SUPERVISOR_COMMS, because SUPERVISOR_COMMS only exists in task runner child processes.

This has been fixed by implementing automatic context detection with three separate secrets backend chains:

Context Detection:

Client contexts (task runner in worker): Detected via SUPERVISOR_COMMS presence
Server contexts (API server, scheduler): Explicitly marked with _AIRFLOW_PROCESS_CONTEXT=server environment variable
Fallback contexts (supervisor, unknown contexts): Neither marker present, uses minimal safe chain

Backend Chains:

Client: EnvironmentVariablesBackend → ExecutionAPISecretsBackend (routes to Execution API via SUPERVISOR_COMMS)
Server: EnvironmentVariablesBackend → MetastoreBackend (direct database access)
Fallback: EnvironmentVariablesBackend only (+ external backends from config like AWS Secrets Manager, Vault)

The fallback chain is crucial for supervisor processes (worker-side, before task runner starts) which need to access external secrets for remote logging setup but should not use MetastoreBackend (to maintain worker isolation).

Architecture Benefits:

Workers (supervisor + task runner) never use MetastoreBackend, maintaining strict isolation
External secrets backends (AWS Secrets Manager, Vault, etc.) work in all three contexts
Supervisor falls back to Execution API client for connections not found in external backends
API server and scheduler have direct database access for optimal performance

Impact:

Hooks like GCSHook, S3Hook now work correctly in log handlers and plugins
No code changes required for existing plugins or hooks
Workers remain isolated from direct database access (network-level DB blocking fully supported)
External secrets work everywhere (workers, supervisor, API server)
Robust handling of unknown contexts with safe minimal chain

See: #56120 <https://github.com/apache/airflow/issues/56120>, #56583 <https://github.com/apache/airflow/issues/56583>, #51816 <https://github.com/apache/airflow/issues/51816>__

Remove insecure dag reports API endpoint that executed user code in API server (#56609)

The /api/v2/dagReports endpoint has been removed because it loaded user DAG files directly in the API server process, violating Airflow's security architecture. This endpoint was not used in the UI and had no known consumers. Use the airflow dags report CLI command instead for DAG loading reports.

Bug Fixes

Fix HITL tasks not properly validating params (#57547) (#58144)
Fix secrets being exposed in Jinja template rendering error messages (#57467) (#57962)
UI: Fix slow loading on next run assets page (#58052) (#58064)
Fix logout not working in airflow-core (#57990) (#58043)
Fix slow loading on UI [(#57820) (#57856), (#57956) (#57973), (#57957) (#57972),(#57869) (#57882), (#57868) (#57918),(#57624) (#57757)]
UI: Fix log download to include .txt file extension (#57991) (#58040)
Fix scheduler using incorrect max_active_runs value from cached DAG (#57619) (#57959)
Fix database migration failures when XCom contains NaN values (#57866) (#57893)
Fix incorrect task context in trigger rule scenarios (#57884) (#57892)
UI: Fix test connection not working (#57811) (#57852)
Fix worker healthcheck timeout not respecting worker-timeout CLI option (#57731) (#57854)
Fix provider hooks not loading when FAB provider is not installed (#57717) (#57830)
Fix slow API responses for task instances list [(#57645) (#57794), (#57646) (#57664),(#57500) (#57735), (#57549) (#57738), (#57450) (#57736),(#57647) (#57732)]
Fix task instance errors when tasks are triggered by trigger rules (#57474) (#57786)
Fix type consistency for extra field in Asset, AssetAlias, and AssetEvent (#57352) (#57728)
Fix upgrade failures when XCom contains NaN in string values (#57614)

Miscellaneous

UI: Add resize functionality to DAG run and task instance notes (#57897) (#58068)
Add Taiwan translation for UI (#58121)
UI: Shorten German translation of Asset in navigation (#57671) (#57690)
Fix code formatting via ruff preview (#57641) (#57670)
Remove remnants from unlimited parallelism in local executor (#57579) (#57644)

Doc Only Changes

Add learning from Airflow 3 migration guide (#57989) (#58083)
Fix duplicate mention of 'DAGs' and 'tasks' in overview documentation (#57524) (#57793)
Document asset event extra storage behavior (#57727) (#57734)