jason810496 opened a new pull request, #69757:
URL: https://github.com/apache/airflow/pull/69757
## Why
`@task.stub` tasks can only be declared argless today, so a Go task that
needs an upstream's output has to hand-write `GetXCom` calls (with the upstream
`task_id` hard-coded in Go, duplicating the wiring the Dag file already
expresses). This PR makes the natural TaskFlow call work across the language
boundary:
```python
@task.stub(queue="golang")
def transform(country: str, extracted: dict): ...
with DAG(...):
transform("uk", extract()) # extract() is a normal Python @task
```
```go
// The runtime binds "uk" onto country and pulls extract's XCom into
extracted.
func transform(ctx sdk.TIRunContext, log *slog.Logger, country string,
extracted map[string]any) error
```
## What
- **Parse time (providers/standard):** `_StubOperator` binds the TaskFlow
call to the stub's signature and serializes an ordered positional-arg spec with
the Dag (`_arg_bindings`): each entry is an XCom reference or a JSON literal,
with `data_type` derived from the parameter annotation.
- **Server (execution API):** `ti_run` returns the spec as a new optional
`TIRunContext.arg_bindings` field — extracted from the serialized-dag blob only
for `_StubOperator` tasks, and stripped for older API versions (Cadwyn change
in the in-progress `2026-06-30` block). The supervisor needs zero changes
because `TIRunContext` is embedded verbatim in `StartupDetails`.
- **Supervisor schema:** new in-progress version `2026-07-30`
(`AddArgBindingsToTIRunContext`); the downgrade path strips the field, so
bundles pinned to `2026-06-16` keep working unchanged.
- **Go SDK:** new `pkg/binding` package. `Analyze` classifies parameters
once at registration (injectables like `context.Context`/`*slog.Logger` vs
JSON-decodable *data parameters*); `Resolve` binds the spec onto the data
parameters in order — literals decode directly, XCom entries pull on demand.
Arity or declared-type mismatches fail the task loudly before the body runs,
replacing the old silent `reflect.Zero` fill.
- Fail-loud v1 exclusions at parse time: `.expand()`/`.partial()` (via a new
generic `supports_expand` opt-out), `map`/`zip`/`concat` XComArgs,
`*args`/`**kwargs`, context-key parameter names, and non-JSON-serializable
literals.
---
##### Was generative AI tooling used to co-author this PR?
- [x] Yes, with help of Claude Code (Fable 5) following [the
guidelines](https://github.com/apache/airflow/blob/main/contributing-docs/05_pull_requests.rst#gen-ai-assisted-contributions)
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