Sync ako/mxcli: splices keep stated positions (#1598), ALTER PAGE object-list items (#1453), view-association check (#1611)

.claude/commands/mxcli-dev/review.md

@@ -52,6 +52,7 @@ proactively. Add a row after every review that surfaces something new.
 | 21 | A registry that reads only one source (an `embed.FS`) has no extension point, so the only way to customise its output is to hand-edit the generated block — which a digest fence then refuses to touch on the next run. The feature ends up hostile to the exact case it was built for | API design | When a guard refuses a user's edit, ask whether the thing being edited should have been authorable. Introduce a source abstraction (`fs.FS` + root) and let a project-local directory shadow the embedded set — the walk functions usually already take a root, so the change is contained |
 | 22 | A test helper that expands a template cross-products every list against every reference (e.g. every `@each $weight` list against every `url()`), inventing artefacts no asset ever shipped and failing on correct input | Test coverage | Scan positionally: a reference must be expanded against the loop it actually sits under. Prove the helper both fires on a real break (delete one shipped file) and stays quiet on correct input — a helper only checked against green code has not been shown to detect anything |
 | 23 | A copy-to-scaffold path renames files but not the identifiers built from the name (`@mixin mxcli-<name>-<alt>`, `@import "mxcli-<name>"`), so two artefacts collide the moment both exist — and the symptom is a rule that silently compiles to nothing | Code correctness | Assert the structural contract on the *generated* artefact, not just the shipped ones: factor the built-in's contract test into a helper and run the scaffold through it. Verify once end to end against the real toolchain and record it |
+| 24 | A new splice refusal routed through the shared `cannotSplice` path changes **mdl 0** too: there a refusal falls back to the whole-flow rebuild, so a headerless script that used to splice now loses its merges, curves and `$ID`s — a silent change of meaning ADR-0011 rules out (#1508 case 6, caught by `TestFlowModify_InsertIsSpliced`) | Language versioning | Gate the new refusal on `flowRebuildRefused.Applies(ctx.LanguageVersion)` so mdl 0 keeps its old splice; add an mdl 0 case asserting "spliced, no MDL-V1-REBUILD" beside the mdl 1 refusal test |
 | 24 | A stacked PR's base merged at an older head: commits pushed to the base branch after its merge never reach `main`, while both PRs read as fine (ako/mxcli#1108 lost its last two commits this way) | Merge hygiene | Before merging any stacked PR, and after pushing to a branch whose PR may already be merged, check each commit with `git merge-base --is-ancestor <sha> origin/main`; retarget the next PR to `main` so it carries the stranded commits, and say so in its description |
 | 24 | A writer leaves out a property Studio Pro always writes (an empty `Documentation`, the empty half of an attribute/association pair) or writes one Mendix does not declare. `mx check`, the build and the runtime stay green, but Mendix's merge/diff engine compares property NAMES and throws, so the document becomes unmergeable once Studio Pro saves it (mendixlabs/mxcli#1373) | BSON writing | The doctype gate's `checkPropertySets` catches it per script: `mx convert -p` re-serializes what is not canonical. Fix the writer, or record Mendix's value with `MXCLI_PROPERTY_SETS_RECORD` + `internal/propertysets/cmd/propdefaults`; never guess a default |
 | 24 | A skill or command still instructs work into a package the repo has deleted (`sdk/mpr` test locations, a symptom table moved to `findings/*.jsonl` years prior) — the doc reads as authoritative and every instruction in it is a compile error or a no-op | Docs quality | When a package is deleted or a doc is restructured, grep `.claude/` for its name in the same PR. A deletion that leaves the guidance behind is worse than no guidance, because the reader trusts it |

.claude/skills/fix-issue/findings/mdl-backend/2026-10-21-splice-shift-leaves-placed-fragment-behind.json

@@ -0,0 +1 @@
+{"area": "mdl/backend", "date": "2026-10-21", "symptom": "create or modify of a nanoflow drawn with @position on every statement, adding an if/else after the declare without @position and editing the two calls in the next if's branch: `spliced: 1 inserted, 1 replaced, 1 dropped`, with `if $Flag` -299 -> 40, its merge 186 -> 525 and the return 530 -> 869, while the replaced calls stayed at (-124, 100)/(60, 100), left of their own decision. Re-running the same script was refused (`the connectors of the If at (40, 200) are redrawn`). With a plain if (no else) the new if took over the stored decision and the restated `if $Flag` was drawn on top of it at (-299, 200), both merges at (186, 200).", "cause": "Three rules that each held alone. makeRoom shifts every top-level node past the cut by the deficit (339); a Replace whose first statement states @position is Placed and written at its stated coordinates, never shifted; movedNode records a move only when the stated position differs from the stored one, so the shifted nodes were never moved back, and the merge is not a move candidate at all. On re-run @merge is geometry but not a position field, so the pair fell to `redrawn`. No-else: lcsStatements weighed ifConditionChanged the same as sameIfShell and the tie went to the earlier pair, so the new if became a condition edit of the stored decision and the restated if a Placed insert, which never runs checkRoom.", "file": "mdl/backend/mfmutator/splice.go (Pin, pinnedPast, makeRoom, Replace), mdl/backend/microflow_mutation.go (MicroflowMutator.Pin), mdl/executor/cmd_flow_modify_patch.go (statedPoints, patch), mdl/executor/cmd_flow_modify.go (lcsStatements weights, mdl 1 gate in planFlowModify)", "insight": "Shift-consistently cannot satisfy idempotence: once the script states -299 and the store says 40, the re-run must move it back or refuse — measured even for a plain one-activity insert into a described flow (+104, then the re-run refused on @merge). So a node at a stated point is pinned and a shift that would move one is refused, naming the room and the node; the mutator pins by point rather than $ID because the node at a stated point may be one a later Placed fragment puts there. Collect stated points from @position, @merge, @start, note and parameter positions, skipping loop bodies (relative coordinates). The control is the same script with the positions after the insert left out: spliced, everything moved by one delta, re-run Unchanged. Gate the pins on mdl 1 (flowRebuildRefused.Applies): under mdl 0 the refusal falls back to the whole-flow rebuild, which deletes the Studio Pro merges and $IDs the shift kept — TestFlowModify_InsertIsSpliced (ADR-0012's describe+insert acceptance, headerless) caught exactly that, and ADR-0011 forbids the change of meaning. Not touched: the shift still moves parameters (y 53) along with the row.", "refs": ["ako/mxcli#1508", "mendixlabs/mxcli#1598"]}

.claude/skills/fix-issue/findings/mdl-backend/2026-10-21-splice-shift-moves-parameters.json

@@ -0,0 +1 @@
+{"area": "mdl/backend", "date": "2026-10-21", "symptom": "A splice that makes room for an inserted fragment (create or modify / alter … insert) moved the flow's parameters along with the row: one if/else inserted into NF_Do moved $Flag from its derived (200, 53) to (539, 53), a longer replace then to (699, 53), and from then on describe printed a parameter @position no script stated. Inserting before the first statement of a two-parameter microflow moved $Count from (300, 53) to (410, 53).", "cause": "mfmutator shift (splice.go) moves every top-level node past the cut, and a Microflows$MicroflowParameter is a top-level object of the unit's object collection (the decoded model keeps parameters apart, so nothing in the executor sees them as nodes). mxcli's derived parameter row is absolute (200 + idx*pitch, 53), right of the start event, so almost every insert's cut falls left of it.", "file": "mdl/backend/mfmutator/splice.go (shifted)", "insight": "Measure the authored convention before deciding what 'the row' is: 63 of 71 Studio Pro-authored parameters (PedApp 19/20, JTSBootLogboek 44/51) sit exactly at the start event's x, all above every other node, none within 60px of the flow line — a parameter belongs to the flow, not to the stretch of line past an insert, and Studio Pro moves nothing on insert. The decoded model hides this: microflows.Microflow carries Parameters apart from ObjectCollection, so a probe that type-switches the collection for *MicroflowParameter does not compile, while the BSON the mutator walks has them inline. Excluding them in shifted also keeps them out of pinnedPast, so a stated parameter position can no longer block a splice it is not in the way of.", "refs": ["ako/mxcli#1547", "ako/mxcli#1508"]}

.claude/skills/fix-issue/findings/mdl-backend/2026-10-22-object-list-item-address.json

@@ -0,0 +1 @@
+{"area": "mdl/backend/pagemutator", "date": "2026-10-22", "symptom": "`insert into grp1 { … }` for an Accordion group: widget \"grp1\" not found — the group stores no Name; `insert into acc1 item@2 { … }` was refused as \"not a navigation list\"; an empty group could not be filled at all", "cause": "object-list items (CustomWidgets$WidgetObject) had no address; resolveNavItem accepted only navigation lists", "file": "`mdl/backend/pagemutator/objectlist_items.go` (resolveObjectListItem, item slots, ObjectListItemValues), `column_hidden_reset.go` (ResetHiddenItemProperties, template nulling/creation), `mdl/executor/alter_hidden_item_slot.go`; grammar `alterTarget` itemSlot", "insight": "The default `docker check` normalises widgets on a temp copy and HID every defect here — run `--no-update-widgets` (the project as stored, what MxBuild and run --local see) or a hidden-slot write and a mode-switching SET both look clean while each is CE0463. Diffing a SET-switched group against a CREATE-made one (TypePointer -> PropertyKey in the JSON dump) found the cause in one step: headerText template filled vs null. Two plausible wrong turns: assuming the schema DefaultValue holds the visible default (it is \"\" — 'Header' lives in the widget package, so a revealed text with no value is refused, not invented), and a check-time hidden-slot refusal that blocked `set (headerRenderMode: 'custom'); insert into …headercontent` — the very fix its own message recommended — because check reads the stored document; it stands down when the statement sets the item first, and exec decides on live values. The item result carries the item schema like a DataGrid2 column, so SET and `.slot` reused existing paths rather than growing new ones", "refs": ["mendixlabs/mxcli#1453", "ako/mxcli#1326"], "ce": ["CE0463", "CE4899"]}

.claude/skills/fix-issue/findings/mdl-executor/2026-10-22-dropdownfilter-default-value-not-a-string-ce0117.json

@@ -0,0 +1 @@
+{"area":"mdl/executor","date":"2026-10-22","symptom":"`column (Attribute: IsActive) { dropdownfilter ddf (defaultValue: 'true') }` passed check and exec, then mx check failed CE0117 \"Error(s) in expression.\" at the drop-down filter (mendixlabs/mxcli#1611 B).","cause":"defaultValue is a pluggable Expression property whose template declares ReturnType String, and a quoted MDL value on an Expression property is the expression's text, so 'true' stored the Boolean expression `true`. No check typed an authored expression against the property's declared return type; the embedded schema read each property's ValueType.Type but not its ReturnType.","fix":"MDL-WIDGET49 (validate_widget_expression_return.go), beside MDL-WIDGET42 in validateWidgetProperties: for a String-returning Expression property, refuse a value that infers as a literal Boolean, Integer or Decimal (exprcheck.InferSourceKind) or is one bare name, with the String-literal spelling as the hint (`defaultValue: '''true'''`). embeddedWidgetSchema.returns records ReturnType.Type per Expression key. Runs with and without a project (the DROPDOWNFILTER definition is built in).","file":"mdl/executor/validate_widget_expression_return.go","insight":"The writer was right and the check was missing: the MDL convention (a quoted value IS the expression text) is what describe prints and what every other expression property relies on, so 'wrap the string for a String-returning property' would have silently changed the meaning of every existing script. Measure the column type separately from the property's return type: '1' failed in an Integer column too — the return type is the widget's, fixed at String, not the attribute's. Judge only what InferSourceKind is sure of: it calls [%CurrentDateTime%] a String, so DateTime is not trusted; Unknown (paths, variables, untyped functions) is never refused.","refs":["mendixlabs/mxcli#1611","ako/mxcli#1539"],"ce":["CE0117"],"rules":["MDL-WIDGET49"]}

.claude/skills/fix-issue/findings/mdl-executor/2026-10-22-view-entity-association-followed-from-target-ce8812.json

@@ -0,0 +1 @@
+{"area":"mdl/executor","date":"2026-10-22","symptom":"A page data source following a view entity's association from the entity it points at — `listview (DataSource: DATABASE FROM $currentObject/M.Stats_Owner/M.Stats)` on a page over M.Owner, where M.Stats selects `o.ID as Stats_Owner` — passed check --references and exec, then mx check failed CE8812 \"Entity 'M.Owner' has no association 'M.Stats_Owner'\" (mendixlabs/mxcli#1611 A). Separately, its remedy `DATABASE M.Stats WHERE [M.Stats_Owner = $currentObject]` (and the microflow `retrieve … where M.Stats_Owner = $x`) was refused by check as naming 'neither an attribute nor an association' when the view entity came from the same script.","cause":"Nothing modelled that a view entity's OQL-derived association (OqlViewAssociationSource) is one-way for a page; MDL-ASSOCDS01's association index had no view flag. And scriptContext recorded only CREATE ASSOCIATION statements, so a script's view associations (its `<alias>.ID as <Name>` columns) were invisible to every name-resolving checker.","fix":"MDL-ASSOCDS02 (validate_view_assoc_reverse.go), hooked into attributeScopeValidator.walk beside MDL-ASSOCDS01: follow the association or `database from` path hop by hop from the widget's context entity and report the first hop that follows a view association from its TO end, with the constrained query as the fix. assocShape.view from Association/CrossAssociation Source == OqlViewAssociationSource; scriptContext.recordViewAssociations registers each view association column through recordAssociation (ends, name index, shape) and marks it view.","file":"mdl/executor/validate_view_assoc_reverse.go","insight":"Measure the remedy you are about to recommend in the same shape the user works in: the constrained query built at 0 errors against a stored view entity, but the check refused it when the view was created in the same script — the reporter's flow — so the new hint would have sent users into a second false refusal. Measured on 11.14.0, one page per shape with uniquely named widgets so mx check's 'at <widget>' attributes each CE8812: refused in list view, data grid, gallery and data view, database and in-memory form, at any hop; accepted from the view side, constrained, and in a microflow association retrieve (so the rule is page data sources only). An entity named Owner is itself CE7247 — rename repro entities before reading the result.","refs":["mendixlabs/mxcli#1611","ako/mxcli#1539"],"ce":["CE8812"],"rules":["MDL-ASSOCDS02"]}

.claude/skills/mendix/alter-page/SKILL.md

@@ -17,10 +17,10 @@ description: "Modify an existing page or snippet's widget tree in place with ALT
 | 482-560 | Examples |
 | 561-651 | DataGrid 2 columns: how to address them, and what you can set |
 | 652-663 | Common Mistakes |
-| 664-692 | Limitations — prefer binding at page creation (ledger finding #45) |
-| 693-700 | Validation Checklist |
-| 701-710 | Related Commands |
-| 711-715 | Related Skills |
+| 664-696 | Limitations — prefer binding at page creation (ledger finding #45) |
+| 697-704 | Validation Checklist |
+| 705-714 | Related Commands |
+| 715-719 | Related Skills |
 
 <!-- /skill-index -->
 # ALTER PAGE / ALTER SNIPPET - Modify Existing Pages and Snippets
@@ -678,6 +678,10 @@ page and bind the buttons at creation time instead of rewiring afterwards:
    view: `replace dvMain.footer with { footer { … } }`, `insert into
    dvMain.footer { … }`, `drop dvMain.footer`.
 
+**An Accordion group has no name either** (`group g1` keeps no `g1`): use
+   `acc1 item@2`, `acc1 item('One')` or `acc1 item(btnIn)`; `.headercontent` is its
+   header slot, refused until `set (headerRenderMode: 'custom') on acc1 item@1`.
+
 **A pluggable widget's slot has no name either.** A Data grid 2's control bar
    (`controlbar { … }` in describe) is a property of the grid, so address it by
    the grid: `insert into dataGrid1.controlbar { actionbutton … }`, `replace

.claude/skills/mendix/create-page/reference/widgets.md

@@ -410,6 +410,8 @@ column (caption: 'Actions') {
 
 > **A list widget needs an association that yields a list.** A list view, data grid or gallery over `$currentObject/M.Assoc` is CE8812 ("A grid association path must result in a list") when the association is a Reference followed from its FROM entity, or a Reference with owner Both from either end (one-to-one). Use a data view for the single object, or a ReferenceSet. `check` reports it as MDL-ASSOCDS01. The reverse of a default Reference (from the TO entity) is a list and fine.
 
+> **A view entity's association is one-way for a page.** The association a view entity derives from its OQL (`select c.ID as Stats_Customer`) can be followed from the view entity only. A data source that follows it from the entity it points at, in any widget and at any hop (`database from $currentObject/M.Stats_Customer/M.Stats`, `$currentObject/M.Stats_Customer`), is CE8812 "Entity 'M.Customer' has no association 'M.Stats_Customer'". Query the view entity instead: `datasource: database M.Stats where [M.Stats_Customer = $currentObject]`. `check` reports it as MDL-ASSOCDS02. A microflow `retrieve … from $Cust/M.Stats_Customer` is accepted.
+
 **With WHERE and SORT BY (inline in DataSource):**
 ```sql
 datagrid dgActive (
@@ -710,6 +712,18 @@ custom attribute (Studio Pro's "Attribute config: Custom"); listing two is refus
 attribute of the Data grid 2 column it sits in ("Auto"), so in a **gallery's**
 `filter { … }` bar, which has no column, the attribute must be named.
 
+`defaultValue:` preselects an option. It is an **expression returning a String**, and a
+quoted MDL value is the expression's text, so the option goes in as a String literal
+inside the quotes, even for a Boolean column:
+
+```sql
+column (Attribute: IsActive) { dropdownfilter ddfActive (defaultValue: '''true''') }
+```
+
+`defaultValue: 'true'` stores the Boolean expression `true`, and `'1'` or a bare name
+like `'Open'` fail the same way: mxbuild reports CE0117 "Error(s) in expression." `check`
+reports it as MDL-WIDGET49. `'empty'` (no preselection) is fine.
+
 Filter by an **association** instead of an attribute — the options are the
 associated objects. Giving the filter a `datasource:` (the OPTION list) selects
 this mode; all three parts are required:

.claude/skills/mendix/write-microflows/SKILL.md

@@ -69,7 +69,7 @@ Choose the mode by who owns the microflow ([choose-edit-mode](../choose-edit-mod
   (targets from `describe microflow X with handles`). `create or modify` of `describe`
   output patches too: unchanged writes nothing; a statement (even one whose handler returns), guard
   clause, `return` value, `if` condition, header clause, parameter (added/retyped; removed only if unused) or stated `@position`/`@start` change is
-  patched in place (a move keeps the node's flows), as is a loop-body activity with new values. A redrawn
+  patched in place (a move keeps the node's flows), as is a loop-body activity with new values ([an insert needing room past a stated `@position`](reference/pitfalls.md#13-inserting-where-the-script-states-every-position)). A redrawn
   `@anchor`/`@curve`, other loop-body change, error handler or other `return` added/taken away rebuilds under
   mdl 0 (`MDL-V1-REBUILD`: IDs renumbered, merges and curves lost) and is refused under `mdl 1;`. **To add,
   remove or reorder in a loop body, `alter … replace` the whole loop** ([pitfalls](reference/pitfalls.md#11-changing-something-inside-a-loop-body)). **To rebuild deliberately, `drop` and `create` in ONE script** — the grants carry only within it ([pitfalls](reference/pitfalls.md#drop--create-is-still-a-new-document)).