Pluggable widget generation, warm local dev loop, ALTER PAGE INSERT INTO, and widget-authoring fixes

[ako]

Summary
This bundles six merged PRs from ako/mxcli into upstream. Together they make pluggable-widget generation version-correct without mx update-widgets, add a Docker-free warm dev loop, extend ALTER PAGE with INSERT INTO, and close a batch of widget-authoring gaps found while authoring real marketplace widgets against MPR v2 projects.
Every change was verified on Mendix 11.12.1 with mx check (0 errors, MPR v2 preserved), and the widget fixes each ship a runnable repro under mdl-examples/bug-tests/.
What’s included

1. Warm local dev loop — mxcli run --local (proposal + implementation)
   A Docker-free, ~1s edit→test loop for Mendix apps plus the provisioning that makes a fresh/reaped web session testable.
   • Long-lived mxbuild --serve (warm ~1s builds vs ~30–60s one-shot), restartRequired-driven hot reload_model vs restart+DDL.
   • Standalone JVM runtime boot (no Docker), web-client rollup bundling (the serve Deploy target skips web/dist), --watch incremental bundler, Playwright screenshots (deep-link + authenticated).
   • --ensure-db provisions local Postgres + app DB; --setup non-blocking bring-up wired into a Claude Code SessionStart hook by mxcli init; empty-repo bootstrap prompt.
2. Multi-version pluggable widgets — resolve CE0463 generically + widget describe
   Makes pluggable-widget generation version-correct across Mendix versions with no per-widget hardcoding and no dependency on mx update-widgets.
   • Definition-side reconciliation against the installed .mpk (per-ValueType scalars, enum option sets, per-property metadata, AllowUpload envelope), full declared PropertyType ordering including inline system properties.
   • editorConfig.js static extractor lifts getProperties visibility idioms into declarative rules so config-hidden textTemplate defaults are nulled exactly as Studio Pro does.
   • DataGrid2 @ Data Widgets 3.10.0 / Mendix 11.12 and ComboBox reach byte-identical definitions vs update-widgets → 0 CE0463.
   • New mxcli widget describe inspects a widget’s discovered format (properties, types, enums, dynamic visibility rules); --format json.
3. Widget-authoring fixes (textTemplate / child slots / Charts CE0463 in v2 / multi-hop XPath / TimeSeries)
   • textTemplate content persisted for generated-def widgets (Badge value, TreeNode headerCaption, Timeline title/description/timeIndication were silently dropped).
   • Container-wrapped child slots routed by name (container children { … }, container customTitle { … }).
   • Visibility fallback merged, not overwritten (extracted wins, hand-authored fallback fills gaps).
   • Generated-widget definitions reconciled — Charts (no embedded template) now emit declared system props in order + run the same .mpk reconciliation; Pie/Column/Line/Bar/Area build byte-identical to update-widgets, no v2→v1 downgrade.
   • Multi-hop association XPath expanded to include the intermediate entity (Assoc1/Entity/Assoc2) → avoids CE1613.
   • Hidden chart-series textTemplates nulled (TimeSeries markerColor/fillColor honor item-level editorConfig gates).
4. ColumnChart runtime JSON.parse fix
   Unset chart-series String properties were emitted as a single space " " instead of "". The chart client feeds customSeriesOptions/customLayout/customConfigurations to JSON.parse behind a value !== "" ? value : "{}" guard; a lone space slips the guard and throws JSON.parse(" "). Now emits "" (schema default), matching Studio Pro. Passed mx check before but failed at runtime.
5. ALTER PAGE — INSERT INTO container
   ALTER PAGE … { insert into { … } } appends widgets as a container’s children — the only way to fill an empty container or add a child without an existing sibling to anchor to.
   • Full-stack: grammar → AST/visitor (Position = "INTO") → executor (children take the target’s own entity context, e.g. a dataview’s entity) → both the MPR-file pagemutator and live-Studio-Pro mcp mutator.
   • Empty containers omit the Widgets list, so it’s created with the Mendix widget-list marker and the grown bson.D written back into its parent.
   • Scope: simple containers (DivContainer, Container, DataView, GroupBox, ScrollContainerRegion, Section). LayoutGrid/TabContainer return a clear error pointing to INSERT BEFORE/AFTER.
   Testing
   • go build ./... clean; go test ./... green except cmd/mxcli/docker TestServeIntegration, a live-mxbuild serve integration test that fails identically on the base branch (stale local fixture: test project v11.6.3 vs cached mxbuild v11.12.1), unrelated to and untouched by these changes.
   • Each widget fix verified on a fresh Mendix 11.12.1 project via mx check (0 errors, mprcontents/ intact); charts and the XPath fix reproduced from real project scripts.
   • Repro scripts under mdl-examples/bug-tests/; doctype example for INSERT INTO; unit tests for mpk declared-order parsing, the editorConfig extractor, and the mutator INTO path.
   • Docs: docs-site pages, MDL_QUICK_REFERENCE.md, alter-page skill, and mxcli syntax help (page + snippet) updated.
   Notes
   • No sdk/mpr write imports added to the executor; new mutation goes through the backend abstraction.
   • Generated ANTLR parser files are not committed (regenerated by make).
   🤖 Generated with Claude Code