Remove `:global` dataclip type

User story

As a developer maintaining Lightning, I want a single, coherent model for dataclips so the wipe and retention pipelines don't need type-specific carve-outs that produce latent bugs like #4795.

Details

The :global dataclip type exists alongside :http_request, :step_result, :saved_input, and :kafka, but its actual semantics are narrow: a system-created, unnamed dataclip that should never be wiped per-run. Its only producer is Lightning.Workflows.Scheduler.invoke_cronjob/1, which seeds the first cron run with %{type: :global, body: %{}}.

That partial support is the root of #4795: Lightning.Invocation.Query.wipe_dataclips/1 excludes :global from its type allowlist, so on :erase_all projects the per-run wipe affects zero rows and Runs.wipe_dataclips/1's {1, [dataclip]} pattern crashes. #4796 patched the crash with a {0, _} no-op clause, but the underlying modeling tension remains: :global is just "a system-created, unnamed saved input that we never wipe per-run."

Implementation notes

Removing :global entirely is the goal. A suggested implementation (open to alternatives):

• Add belongs_to :created_by, User to Dataclip, mirroring Run.created_by (nullable column). A blank created_by in the UI means "created by the system" — same convention used for runs today.
• Change Scheduler.invoke_cronjob/1 to seed :saved_input with created_by: nil instead of :global.
• Drop :global from Dataclip.@source_types. Data-migrate existing rows to :saved_input (leaving created_by_id NULL).
• Simplify Lightning.Invocation.Query.wipe_dataclips/1 so the only exclusion is is_nil(d.name) — named saved inputs never get wiped, everything else does.

Callsites that will need changes:

• lib/lightning/invocation/dataclip.ex — schema + @source_types + docstring
• lib/lightning/workflows/scheduler.ex:90-97 — cron-first-run seed
• lib/lightning/invocation/query.ex:316-324 — wipe_dataclips/1
• lib/lightning/runs.ex:182 — keep the {0, _} no-op clause (named dataclips can still produce zero-row updates)
• lib/lightning/projects/sandboxes.ex:97 — @allowed_dataclip_types
• lib/lightning_web/live/components/common.ex:574 and lib/lightning_web/live/components/icon.ex:18 — display enum and badge styling
• Tests under test/lightning/workflows/scheduler_test.exs, test/lightning/sandboxes_test.exs, test/lightning/invocation_test.exs, test/lightning_web/controllers/dataclip_controller_test.exs, test/lightning_web/channels/run_channel_test.exs

Open questions

• on_delete for dataclips.created_by_id: :restrict (matches Run, see migration 20260319103734) or :nilify_all?
• Should :kafka dataclips be wiped by the simplified query? They are excluded today under the explicit type allowlist; with an is_nil(d.name)-only filter they would be included.

Release notes

Internal cleanup. The :global dataclip type is removed; existing global dataclips are migrated to :saved_input and remain accessible to jobs and sandboxes as before. Adds a created_by association on dataclips (nullable) so the UI can later distinguish user-created from system-seeded saved inputs.

User acceptance criteria

• :global no longer appears in Lightning.Invocation.Dataclip.@source_types.
• Existing :global rows have been migrated to :saved_input with created_by_id NULL.
• The first cron run of a previously-unrun cron workflow seeds a :saved_input dataclip with created_by_id NULL.
• fetch:dataclip on an :erase_all project with any non-named dataclip succeeds and wipes the body.
• Named dataclips (saved inputs with a name) are never wiped by Runs.wipe_dataclips/1.

Related

• #4795 — the crash that surfaced this modeling tension
• #4796 — the {0, _} patch

Start with lib/lightning/invocation/dataclip.ex and trace the scheduler, wipe query, sandbox, and LiveView callsites listed in the issue. Run the specified scheduler, sandbox, invocation, controller, and channel tests; the work is done when global rows and cron seeds use saved_input, named dataclips remain protected, and erase_all wipes eligible dataclips without crashing.