Drop the Dag inventory from Lang-SDK bundle metadata

[jason810496]

Stack (bottom to top): #73970, #73971, #73972, #73973, #73974, #73975, #73976, #73977, #74030, #74031, #74032, #74033, #74067, #74135, #74136, #74137, #74138, #74139, #74140, #74141

Why

Nothing reads the Dag and task ids that a bundle's metadata lists any more. The Dag processor asks the artifact which task handlers it registers, and the worker runs the file a stub task is bound to (ADR-0014). This PR removes the inventory and what existed only to produce it: the Go packer no longer runs the bundle binary with --airflow-metadata, and the TypeScript packer no longer embeds the handlers it checks. Spec version 1.0 stays, since older manifests still validate.

What changes

The Go packer never runs the binary it packs, so a binary built for any platform packs on any host, with no manifest to capture first:

# before: a binary built for another platform needed a manifest captured by running it there
./my-bundle --airflow-metadata > airflow-metadata.yaml
go tool airflow-go-pack --executable ./my-bundle --source main.go --airflow-metadata airflow-metadata.yaml

# after
GOOS=linux GOARCH=amd64 go build -o my-bundle ./example/bundle
go tool airflow-go-pack --executable ./my-bundle --source ./example/bundle/main.go

The manifest it writes has no dags mapping, and the packer refuses a binary built against another go-sdk than its own:

airflow_bundle_metadata_version: "1.0"
sdk:
  language: "go"
  version: "(devel)"
  supervisor_schema_version: "2026-10-30"
source: "main.go"
digests:
  integrity: "6fce067a..."
  cache: "1f86d77a..."

error: the bundle binary was built against go-sdk v0.1.0, but airflow-go-pack was built against go-sdk v0.2.0; pack with `go tool airflow-go-pack` from the module that built the binary, so both use the same go-sdk

• Go packer. supervisor_schema_version comes from the packer's own go-sdk, and the SDK version from the binary's build information, which Go keeps in a stripped binary and for any target platform. The two go-sdk builds are accepted without a comparison when go-sdk is the main module of both, as inside the SDK module, because Go stamps the main module's version from version control. Otherwise the version and the replacement must be equal, in build mode too, so a flag after -- such as -modfile cannot change the module graph unnoticed. A binary that does not link go-sdk is refused. The code that ran the binary and decoded its output, the host build for --goos and --goarch, the Dag and task id warnings, the --airflow-metadata flag and the Dag count in the output line are gone.
• Go bundle binary. --airflow-metadata, --format and DumpAirflowMetadata are removed, so the binary speaks only the coordinator protocol. --comm and --logs are the only names Serve reserves, so a bundle may define flags named airflow-metadata or format of its own. The manifest type loses its Dag inventory.
• TypeScript. airflow-ts-pack still runs the bundle with --airflow-metadata, for the schema version, the source file of each Dag declared in TypeScript and finalizing those Dags. It still checks the handlers the bundle reports (it serves something, a Dag with no tasks, ids the server would reject) but no longer embeds them: the metadata line has airflow_bundle_metadata_version, sdk, entrypoint_path and dag_source_paths.
• Schema and specs. airflow-metadata.schema.json no longer requires or describes dags. The executable bundle spec drops the field and its example, says the packer writes the manifest, and says consumers ignore a dags mapping from an older packer. The TypeScript spec shows the fields the encoder writes in place of a source field it does not write, and says an older task_handlers mapping is ignored.
• Older bundles. A bundle packed before this PR still carries dags (Go) or task_handlers (TypeScript), and every reader accepts it. The TypeScript golden bundle is kept in both forms for the Python reader.
• Docs. The Go and TypeScript pages, the Language SDK guide, the READMEs, the contributor guide for a new Language SDK, the Justfile and the e2e docstring no longer say the packer runs the binary or that the manifest lists Dag and task ids, and go-sdk ADRs 0001 to 0005 get a status note that --airflow-metadata is retired. ADR-0014 keeps the status Proposed and its Consequences describe what the code does. The Bundle.serve documentation says a stub task whose handler is left out fails the import of its Python Dag file, and a task that still reaches the bundle without its handler is marked removed.
• Documentation drift fixed on the way. The TypeScript page and README documented a --source pack option that the CLI rejects with Unknown option --source, and the metadata sample of the TypeScript spec showed a source field the encoder does not write. Both are corrected. The spec's container, layout header, source section and reader steps still describe a single source region, which ADR-0015 replaced with one region per Dag file. That is left to a follow-up.

What the next PRs can rely on

• The Go pack runs no binary. It prints Wrote bundle <path> (sdk=go/<version>), and go tool airflow-go-pack inspect <bundle> prints a manifest without dags. Packing in a module that replaces go-sdk with a local path, such as kubernetes-tests/lang_sdk/go_example, records the version (devel).
• The TypeScript bundle's //# airflowMetadata= line has no task_handlers. airflow-ts-pack still runs the bundle and prints its pack-time warnings to stderr.
• No supervisor message changed, so the schema snapshot and the Go models are unchanged.

How to test

(cd go-sdk && go vet ./... && go test ./...)
(cd ts-sdk && pnpm install --frozen-lockfile && pnpm typecheck && pnpm lint && pnpm format:check && pnpm test && pnpm build)
uv run --project task-sdk --with-editable shared/secrets_masker pytest task-sdk/tests/task_sdk/coordinators/ -q
uv run --project airflow-core --with-editable shared/secrets_masker pytest airflow-core/tests/unit/dag_processing/ -q
AIRFLOW_LANG_SDK_REAL_PROBE_TESTS=1 uv run --project airflow-core --with-editable shared/secrets_masker pytest airflow-core/tests/unit/dag_processing/test_task_handler_processor_go.py airflow-core/tests/unit/dag_processing/test_task_handler_processor_ts.py airflow-core/tests/unit/dag_processing/test_task_handler_processor_java.py -v
prek run check-go-example-mod-tidy generate-supervisor-schemas-snapshot check-go-sdk-generated-drift --all-files
(cd kubernetes-tests/lang_sdk/go_example && CGO_ENABLED=0 go tool airflow-go-pack --output /tmp/go_example_bundle . && go tool airflow-go-pack inspect /tmp/go_example_bundle)

Ran:

• go vet and go test ./... in go-sdk: 13 packages pass, 32 tests in the packer's package. They include a real two-module test: a module that replaces go-sdk with a local path packs with its own go tool and is accepted, a binary built against another go-sdk version is refused with both versions in the error, so is a binary built inside go-sdk when the packer replaces it, and so is a build with -modfile pointing at another go.mod. With an empty Go build cache the packer's package tests take 9 seconds.
• ts-sdk: pnpm install --frozen-lockfile, typecheck, lint, format check and build pass, and pnpm test passes 611 tests.
• task-sdk coordinators/: 314 passed. airflow-core dag_processing/: 798 passed, 19 skipped (10 real probe tests, which need AIRFLOW_LANG_SDK_REAL_PROBE_TESTS=1, and 9 that need FabAuthManager, a system test module or a Postgres or MySQL backend).
• The real probes with Node 22.22.0, pnpm, JDK 11 and Go 1.25: 10 passed (Go 4, TypeScript 4, Java 2). The Go probe validates the packed manifest against the published schema, and the TypeScript probe checks the packed metadata has no task_handlers.
• kubernetes-tests/lang_sdk/go_example packs with go tool airflow-go-pack, also with --goos linux --goarch amd64, and inspect shows no dags. The packed bundle exits with unknown flag: --airflow-metadata when run with the removed flag. check-go-example-mod-tidy, check-go-sdk-generated-drift and generate-supervisor-schemas-snapshot pass and change nothing.
• prek run --from-ref <parent> --stage pre-commit passed. mypy-airflow-core, mypy-task-sdk and mypy-airflow-e2e-tests passed with --all-files.
• The compose e2e modes and the Kubernetes test ran once, on the last layer of the stack, and passed (results in Add e2e tests for checking stub tasks against their task handlers #74140 and Read the k8s Java task handler bundle from S3 and test failure cases #74141). They pack with this PR's packers: the Go pack ran no binary, the Go manifests have no dags and the TypeScript metadata has no task_handlers.

The tests of each behavior change fail without it, checked by reverting the code of its commit: 13 of the Go packer's 32 tests fail against the old packer (one of them with its 4 subtests, and the 3 version tests do not compile without the new check), the 3 bundle binary flag tests fail against the old flags, the 6 TypeScript encoder and pack tests and the Python fixture test fail against the old encoder, and the 4 schema tests fail against the old schema and spec. The tests that read an older bundle, with dags or task_handlers in its manifest (inspect, the executable and Node coordinators, the Node bundle reader), pass before and after: they guard what the PR keeps.

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