Issue: format2 conversion validation requires a connected conditional param

Status: open / not started Branch: Galaxy wf_tool_state Found: while swapping legacy roundtrip fixtures (2026-06-06); surfaced by test/unit/workflows/test_roundtrip.py::TestRoundTripSweep::test_sweep_report on framework workflow empty_collection_sort.

Filename note: ..._SHOULDNT_BY_MAYBE looks like a typo — probably ..._SHOULDNT_BE_MAYBE (“required when it shouldn’t be”) or ..._SHOULDNT_BUT_MAYBE. Rename when convenient.

TL;DR

Native→format2 conversion of a __FILTER_FROM_FILE__ step declines (raises ConversionValidationFailure) because the post-conversion format2 validation demands how.filter_source, even though filter_source is satisfied by a connection (how|filter_source → filter_file), not by state. The required conditional param is flagged missing when it shouldn’t be — it’s connected. Production degrades gracefully (gxformat2 keeps native state), so this is a conversion-fidelity gap, not a runtime break.

Same strictness family as the disconnected-optional RuntimeValue work (strict workflow_step model vs. connection-aware reality), but a distinct mechanism: a nested conditional whose required leaf is connected, with the conditional selector absent from tool_state.

Symptom

test_sweep_report (strict per-step sweep) fails:

format2/empty_collection_sort: step 2 (__FILTER_FROM_FILE__):
  Failed to validate resulting cleaned step - not going to convert to an unvalidated tool state

Underlying pydantic error from _validate_converted_result:

pydantic_core.ValidationError: 1 validation error for DynamicModelForTool
how.__absent__.filter_source
  Field required [type=missing, input_value={}, input_type=dict]

test_full_roundtrip_sweep does NOT fail on it — when conversion declines, gxformat2 keeps native state and the native→format2→native’ round-trip is an identity. Only the strict per-step sweep (which counts decline-to-convert as failure) trips.

Reproduction

Source workflow lib/galaxy_test/workflow/empty_collection_sort.gxwf.yml:

steps:
  filter_collection:
    tool_id: __FILTER_FROM_FILE__
    in:
       input: input                  # collection input, connected
       how|filter_source: filter_file # data input, connected INTO the conditional

After python_to_workflow, native step 2 is:

tool_id: __FILTER_FROM_FILE__
tool_state: {"__page__": 0}          # NO 'how' selector / __current_case__
input_connections: {
  'input':            [{'id': 0, 'output_name': 'output'}],
  'how|filter_source':[{'id': 1, 'output_name': 'output'}],   # filter_source IS connected
}

from galaxy.tool_util.workflow_state.convert import convert_state_to_format2
from galaxy.workflow.gx_validator import GET_TOOL_INFO
convert_state_to_format2(step2, GET_TOOL_INFO)   # raises ConversionValidationFailure

Tool shape (__FILTER_FROM_FILE__, filter_from_file_1.1.0.xml)

input         :: gx_data_collection  optional=False
how           :: gx_conditional      optional=False
  when[remove_if_absent]:  filter_source :: gx_data optional=False
  when[remove_if_present]: filter_source :: gx_data optional=False

filter_source is a required leaf inside both branches of the how conditional.

Root cause (hypothesis)

1. tool_state carries no how selector (no __current_case__), so the converter/ validator can’t pick a when branch — pydantic reports the conditional as how.__absent__.
2. filter_source is satisfied via the connection how|filter_source, recorded in the format2 in: block — NOT in state.
3. _validate_converted_result → validate_format2_state(inputs, state, in_dict) (convert.py:120-124) is passed the in_dict, but the connection at the nested path how|filter_source is apparently not recognized as satisfying the nested-conditional required leaf. The strict workflow_step model demands filter_source in state.

So the validation models a connected conditional leaf as missing. The connection-aware path (workflow_step_linked, which admits ConnectedValue) is either not used here or does not descend into a conditional whose selector is absent.

This rhymes with the broader plan’s finding: the strict workflow_step schema rejects shapes that are legal once connections are considered. Here the twist is the absent conditional discriminator — the branch is only knowable from the connection path how|filter_source.

Impact / scope

• Production: benign. make_convert_tool_state catches ConversionValidationFailure and returns None; gxformat2 falls back to copying native tool_state. The workflow imports; it just doesn’t get cleaned format2 state for this step. (Same “better ugly than corrupt” contract as elsewhere.)
• Tests: blocks the strict per-step sweep from going green. Currently the only non-legacy failure in test_roundtrip.py after the fixture swap.
• Corpus: unknown how many IWC/real workflows hit connected-into-conditional with an absent selector — worth a sweep count (the broader plan already greps IWC for related shapes).

Proposed fix directions (pick during focused work)

• OPTION_CONNECTION_AWARE_NESTED — make the post-conversion validation recognize a connection at a nested conditional path (how|filter_source) as satisfying that leaf, and infer/relax the conditional branch when the discriminator is absent but a branch-specific leaf is connected. (Mirrors workflow_step_linked ConnectedValue admission, extended to conditionals.)
• OPTION_VALIDATE_AGAINST_LINKED — validate the cleaned state against the connection-aware (workflow_step_linked) model with the in: connections injected, rather than the strict workflow_step model, when connections are present (parallels the plan’s validate_format2_state linked-validation idea).
• OPTION_INFER_SELECTOR_FROM_CONNECTION — when a conditional’s discriminator is absent but a connection targets a path under exactly one branch, treat that branch as selected for validation purposes.

Key files

• lib/galaxy/tool_util/workflow_state/convert.py:110-124 (_convert_valid_state_to_format2 → _validate_converted_result → validate_format2_state)
• lib/galaxy/tool_util/workflow_state/validation_format2.py (validate_format2_state)
• lib/galaxy/tools/filter_from_file_1.1.0.xml (the tool)
• lib/galaxy_test/workflow/empty_collection_sort.gxwf.yml (repro fixture)
• test/unit/workflows/test_roundtrip.py (TestRoundTripSweep::test_sweep_report)

Open questions

1. Does validate_format2_state already attempt connection-aware (workflow_step_linked) validation, and if so why doesn’t the nested how|filter_source connection register?
2. Is the absent how selector the actual blocker (no branch to validate), or is it purely the connection-not-recognized issue? (The how.__absent__ in the error suggests the former contributes.)
3. Corpus frequency: how many real workflows connect into a conditional leaf with no stored selector? Drives priority.
4. Relationship to the disconnected-optional RuntimeValue plan — share the linked-model validation fix, or fix independently?