mxcli check accepts `declare list = empty` but Studio Pro rejects it (CE0053/CE0038)

[ako]

Summary

declare $list list of Module.Entity = empty; parses and passes mxcli check, but Studio Pro's mx check rejects it with CE0053 ("type not allowed") and CE0038 ("value required"). In Mendix, declare maps to a Create Variable activity, which is not allowed for list data types (empty lists must use a Create List activity). So mxcli green-lights logic that crashes the project on open / mx check.

This is the concrete instance behind the broader "mxcli check vs mx check divergence" feedback.

Reproduction

create microflow MyFirstModule.TestEmptyList()
begin
  declare $Items list of MyFirstModule.Cars = empty;
end

$ ./bin/mxcli check /tmp/t.mdl
✓ Syntax OK (1 statements)
Check passed!

…then opening the project in Studio Pro → CE0053 + CE0038.

Why it slips through today

• Lint rule MDL002 only flags an empty-list variable when it is used as a LOOP source (mdl/executor/validate_microflow.go ~line 139), not the declare … = empty itself.
• The skills/docs present it as valid syntax with no warning:
  • .claude/skills/mendix/write-microflows.md:137
  • .claude/skills/mendix/check-syntax.md:21
  • .claude/skills/mendix/patterns-data-processing.md:217,261,300
  • CLAUDE.md:469 even claims violations are "caught by mxcli check" (aspirational).

Proposed fix (options)

1. Validation: mxcli check should error (or warn) on list-typed declare … = empty, pointing users to: pass the list as a microflow parameter, populate it immediately with retrieve, or use a Create List construct.
2. Or make it valid: emit a Create List activity for list-typed declare, so the output is accepted by Studio Pro.
3. Docs: update the skills/CLAUDE.md so the accumulation pattern shown is actually Studio-Pro-valid.

Reported via external user feedback (AI-agent MDL generation).

[github-actions]

Issue Triage

Summary:
The issue reports that mxcli check incorrectly accepts a declare … list = empty statement, while Mendix Studio Pro rejects it with errors CE0053/CE0038.

Checklist for bug report completeness

Required info	Present?	Details
mxcli version	❌	Not mentioned
Mendix version	❌	Not mentioned
Scenario (what the user was trying to do)	✅	MDL script with declare $Items list of MyFirstModule.Cars = empty; and running mxcli check
Expected output	✅	mxcli check should error/warn on list‑typed declare … = empty
Experienced output	✅	mxcli check passes; Studio Pro shows CE0053/CE0038
AI bug report (mxcli diag --bundle or session log)	❌	Not provided

Missing information:
Please add the following to help us reproduce and fix the issue:

1. The version of mxcli you used (mxcli --version or commit/build info).
2. The Mendix version of the project you are checking (e.g., 10.6, 9.24).
3. If possible, run mxcli diag --bundle and attach the resulting archive, or at least share the relevant session log.

Once those details are added, we’ll be able to investigate further. Thank you for bringing this to our attention!

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