fix(pages): four silent page changes — list view Editable, data view footer addressing, page-variable input binding, pluggable REPLACE passthrough

[ako]

Four silent page changes. The rule behind all four: when a statement reports success, it must have written what it says, and describe must not drop anything that is stored.

Fixes mendixlabs#1214
Fixes mendixlabs#1235
Fixes mendixlabs#1247
Fixes mendixlabs#293
Closes #528

What changed (one commit per item)

mendixlabs#1214: set Editable = true on <listview>. This printed "Altered page" and stored nothing. A list view or data view stores Editable as a boolean, but the setter only wrote strings, so the boolean fell through and the setter returned nil. Now the type of the stored value decides what the property accepts:

• list view or data view: true / false
• input widget: Always / Never, written in canonical case ('never' used to be stored as typed)

Conditional without an expression, a boolean on an input, and Editable on a widget that has none are all refused. These are new rejections. They replace a silent no-op, or a wrong write in the bare-Conditional case. set Editable = [expr] now also writes the Conditional enum next to its settings element, the same way CREATE does.

#528 / #293: data view footer. A footer is a region of its data view. Its widgets are stored in the data view's FooterWidgets, and the footer itself has no stored name. That is why the name the script wrote, and the footer1 that describe invented, both resolved to nothing.

• dvMain.footer is now an ALTER target, addressed the same way scroll-container regions are:
  • INSERT INTO appends. Filling an empty footer turns ShowFooter on.
  • REPLACE swaps the whole content. A describe-style footer { … } block is unwrapped.
  • DROP empties the footer.
  • A miss names the footer addresses that do exist on the page.
• REPLACE may now reuse the names of the widgets it removes, i.e. the target's descendants. Restating btnSave used to fail with "duplicate widget name".
• A name on a data view footer is reported as MDL-DEPR005 (unstored widget name), exactly like a layout-grid row's name. The AST is identical either way, so nothing written changes. Describe prints footer { … }. The 66 gated doc, example and skill occurrences were rewritten, and the grammar's own doc example (replace footer1 with …) was corrected.

mendixlabs#1235: input bound to a page variable. I measured the stored shape over the Studio Pro MCP tunnel on TestApp (Pages.Probe1235_pagevar): sourceVariable {localVariable: "ShowAll"}, no attributeRef, and ped_check_errors clean.

• checkbox cb (Attribute: $ShowAll) now writes that shape when $ShowAll is a declared page variable.
• check validates the name against the document's Variables: (a name not declared there is still MDL-WIDGET34).
• ALTER sees the stored variables.
• Describe prints Attribute: $ShowAll.
• mx check then reported CE6553 for a text box, so text box and text area bound to a variable now get MaxLengthCode 0 (unlimited, Studio Pro's default for variables). -1 means "attribute length", which a variable doesn't have.

mendixlabs#1247: REPLACE of a pluggable widget. This applies #830's passthrough principle per property.

• When one pluggable widget is replaced by one of the same package, the executor also builds the stored widget as describe prints it (the baseline).
• The mutator keeps the stored Type, plus every property and widget field on which the replacement and the baseline agree. Those values come from the template, not from the statement.
• Values that differ are grafted in, with their TypePointers re-aimed at the stored Type by key path.
• Anything that can't be lined up falls back to the old plain replace.
• On TestApp's Studio Pro-authored Rules.BusinessRule_NewEdit, adding sort by Name asc to comboBox1 used to change three things: the sort, Editable "Never" → "Always", and an expression property's PrimitiveValue "" → "false". Now only the sort changes.

ADR-0011

• ALTER PAGE … SET Editable = true ON <listview> reports "Altered page" but the list view stays Editable = false (CREATE with Editable: true works) mendixlabs/mxcli#1214: the new refusals replace "Altered page" with nothing written, or with an invalid value (refusing a wrong write).
• ALTER PAGE … REPLACE on a pluggable Combobox silently resets properties the statement doesn't restate (placeholder translations, readOnlyStyle); describe and diff-local don't show the loss mendixlabs/mxcli#1247: fixes a silent wrong write, so the fix applies under both mdl 0 and mdl 1.
• Input widget bound to a page variable: MDL cannot write it (MDL-WIDGET34) and DESCRIBE PAGE silently drops the binding mendixlabs/mxcli#1235 and the footer addressing only accept input that used to be refused.
• The footer-name deprecation is a warning under mdl 0 and mdl 1 (RemovedIn 2) and does not change what is written.

Test plan (what I ran)

• Unit tests, each written first and seen failing with the reported symptom:
  • pagemutator: Editable (bool, enum, no property), footer region (resolve, insert, replace, drop, hint), mergeUnstatedPluggable
  • visitor and upgrade: MDL-DEPR005 on a data view footer, footer outside a data view keeps its name
  • executor: page-variable builders for all 6 input kinds, check, describe
  • modelsdk: maxLengthCodeFor
• Revert checks:
  • ALTER PAGE … SET Editable = true ON <listview> reports "Altered page" but the list view stays Editable = false (CREATE with Editable: true works) mendixlabs/mxcli#1214: tests fail with Editable = false after set Editable = true
  • footer: fails with widget "dvMain" has no columns
  • DEPR005 entry removed: visitor and upgrade tests fail
  • Input widget bound to a page variable: MDL cannot write it (MDL-WIDGET34) and DESCRIBE PAGE silently drops the binding mendixlabs/mxcli#1235: implementation removed, builder/check/describe tests fail (describe binding = "", declared variable refused)
  • ALTER PAGE … REPLACE on a pluggable Combobox silently resets properties the statement doesn't restate (placeholder translations, readOnlyStyle); describe and diff-local don't show the loss mendixlabs/mxcli#1247: merge disabled, roundtrip test fails with Editable = "Always" and PrimitiveValue: -> false
• Integration:
  • go test -tags integration ./mdl/executor -run 'TestAlterPage_SetListViewEditable|TestAlterPage_DataViewFooterRegion|TestPageVariableInputBinding_RoundTrip': describe → exec → describe stable for footer and page variable
  • mdl/roundtrip TestReplacePluggableKeepsWhatTheStatementDoesNotState on TestApp (Studio Pro-authored), including twice-exec writes nothing
  • full make test-integration-roundtrip green
• Manual runs on a TestApp copy: rehearsals of ALTER PAGE … SET Editable = true ON <listview> reports "Altered page" but the list view stays Editable = false (CREATE with Editable: true works) mendixlabs/mxcli#1214, A footer's name inside a dataview is silently discarded, so ALTER PAGE cannot address it #528 and Input widget bound to a page variable: MDL cannot write it (MDL-WIDGET34) and DESCRIBE PAGE silently drops the binding mendixlabs/mxcli#1235, then mxcli docker check reports 0 errors. Before the MaxLengthCode fix it reported CE6553. The ALTER PAGE … REPLACE on a pluggable Combobox silently resets properties the statement doesn't restate (placeholder translations, readOnlyStyle); describe and diff-local don't show the loss mendixlabs/mxcli#1247 REPLACE run twice: the second run writes no file, and mxcli docker check reports 0 errors.
• make build, make lint, make check-conformance, make check-migration-reference, make check-findings, go test ./cmd/mxcli/ (skill budgets), plus scoped go test for pagemutator, modelsdk, executor, visitor, upgrade, deprecation and conformance.

Not in this PR (follow-ups)

• create or modify page with a changed pluggable widget still rebuilds unstated properties from the template. The fix(pages): keep an unchanged pluggable widget's stored Type and Object (#721 L4) #830 passthrough there is all-or-nothing, and the same baseline merge could be applied.
• Describe still doesn't print the combobox's emptyOptionText or readOnlyStyle. REPLACE now keeps them, but they still aren't visible in describe.
• A name on a footer inside a fragment used in a data view is still discarded without a warning, because the visitor can't see the eventual parent.

🤖 Generated with Claude Code

[ako]

Independent review: pushed two commits.

• 1655160: the ALTER PAGE … REPLACE on a pluggable Combobox silently resets properties the statement doesn't restate (placeholder translations, readOnlyStyle); describe and diff-local don't show the loss mendixlabs/mxcli#1247 merge did not apply to a DataGrid 2. On TestApp's Studio Pro-authored Rules.BusinessRule_Overview, restating dataGrid2_1 with one column caption changed fell back to the template rebuild. That reset itemSelectionMethod (rowClick -> checkbox), onClickTrigger, and every column's and filter's unmapped properties. There were two causes. The graft re-aimed the TypePointers of the nested filter widgets, which point into their own Type. And the columns list was grafted whole. The fix leaves a nested pluggable widget as built and merges an object list object by object. New roundtrip test TestReplaceDataGridKeepsWhatTheStatementDoesNotState (including the twice-exec check) and two unit tests. Each was seen failing with its part of the fix reverted.
• 178e740: the MDL-WIDGET34 hint suggested Variables: { … } (MDL-DEPR123); it now uses ( … ).

Ran: make build, lint, check-conformance, go test ./cmd/mxcli, pagemutator + executor unit tests, make test-integration-roundtrip (pass), and the executor integration tests from the PR. On a TestApp copy edited by every scenario (Editable, footer insert/replace/drop, page-variable inputs of six kinds, DataGrid 2 caption change and column add), mxcli docker check reported 0 errors and each script, run a second time, wrote nothing.

🤖 Generated with Claude Code