R4: one argument form (Param = expr) and with ({n} = …) text templates (#751)

[ako]

Part of #751 (R4 in full; the R3 alter … set ( Key: value ) half is left for a follow-up — see below). Tracking: #714.

What changes

One argument form at every call site: Param = expression (no $, = not :):
call microflow/nanoflow/java action/javascript action/external action, web service operation, execute database query, send rest request … with (id = $X), show page M.P(Order = $O), page/button actions and microflow/nanoflow data sources (Action: microflow M.F(Order = $currentObject)), and workflow calls: call microflow M.F(Order = $WorkflowContext) as act1 comment '…' (bare expression, right after the callee).

One text-template form: with ({1} = e, …) for show message and validation feedback (already the form of log and REST templates).

Old spellings are registered deprecated aliases (both language versions warn, fmt --upgrade rewrites them, rewrites computed from the parse tree):

Code	Old	Canonical
MDL-DEPR006	$Param = e	Param = e (quoted only when the name is not a valid parameterName)
MDL-DEPR007	Param: e (show page, page actions, data sources)	Param = e
MDL-DEPR008	workflow with (Param = '<expr>')	(Param = <expr>) after the callee
MDL-DEPR009	objects [a, b] / parameters [a, b]	with ({1} = a, {2} = b)

describe emits the canonical forms everywhere (microflow show page, show message, validation feedback, send rest request, page actions incl. inferred show_page args, data sources, workflow calls). It now also emits a validation feedback's template arguments, which it silently dropped (describe → exec lost them; finding recorded).

Skills (make sync-skills), docs-site, MDL_QUICK_REFERENCE.md, mxcli syntax entries and CHANGELOG are migrated.

Design choices the ADRs did not settle

• Workflow string argument → no meaning change. The new form is new syntax (a list after the callee), so nothing existing changes meaning; the old with (P = '<expr>') keeps its meaning (the string's content is the expression) and is an alias (MDL-DEPR008), not a gated change. The rewrite unquotes only when the content parses as an MDL expression and reads back as exactly the same stored text (visitor.BareExpression); otherwise it is left and reported (Result.Unrewritten). Writing both lists on one call is an error.
• describe fallback for workflow arguments. A stored expression that does not read back as itself when bare (surrounding whitespace, text the MDL expression grammar can't parse) is described in the string form, which carries it byte for byte — describe must never alter a stored expression. This is the only place describe can emit a deprecated spelling, and only for such expressions.
• send rest request keeps its with (…) clause; only the binding form changes ($id = e → id = e). Moving the list next to the operation is a bracket question (R2, R2: three brackets, three meanings — integration documents, navigation/menus, on error, while (3.4) #754), not R4.
• with ({n} = …) on show message / validation feedback is stored by number; the numbers must be exactly 1..N (the model holds a positional list), otherwise a parse error.
• Registry codes 006–009 were taken in order; parallel wave-2 PRs may collide on numbers and need a renumber at merge.

Not in this PR (follow-ups)

• R3: alter <type> X set ( Key: value, … ) with exactly create's keys for page set, odata alter, settings, styling; removing optional colons (type reference, modify attribute A: T). Overlaps R6/R7/R9/R10: verbs, session commands, metadata placement, Studio Pro document names (3.5–3.6) #755 (alter settings runtime) and the existing MDL-DEPR101–103 alter-page aliases, so it is better as its own PR.
• Snippet call params {$Asset: $var} and fragment args ($p: $Data) still use :/$ (not call sites in the R4 list; fragment args are mxcli macros).
• mdl-examples/ scripts were not rewritten (the examples upgrade test covers them).

Test plan (what I ran)

• make build, make lint (Go + TS) — pass.
• go test ./mdl/visitor/ ./mdl/upgrade/ ./mdl/deprecation/ ./mdl/grammar/ ./mdl/executor/ ./mdl/linter/... ./cmd/mxcli/... — pass (incl. TestUpgrade_ExamplesKeepTheirStatements, TestRegistryExamplesRecordTheirCode, TestGrammarAliasesAreRegistered, TestLargeSkillsWereSplit).
• go test -tags integration ./mdl/roundtrip/ (PedApp + TestApp, execute-both upgrade property, describe: end every statement with ';', never print '/' (#744) #745 terminator test) — pass; no allowlist entries added.
• New tests: TestArgumentBindingAliases (17 call-site cases: each old form records its code, has a fix, and builds exactly the canonical statement), workflow bare-expression / no-rewrite / two-lists tests, template numbering, TestUpgrade_ArgumentBinding (golden rewrite keeping case/comments/layout, idempotent), TestUpgrade_WorkflowStringArgumentWithoutBareForm, TestDescribe_* (show message, validation feedback, send rest request, workflow incl. fallback — each output re-parses with no deprecation).
• Revert checks: restoring the four describe emitters to main fails TestDescribe_* and the updated describe expectations (old output also records MDL-DEPR006/008/009); disabling the visitor's Exit* hooks fails TestArgumentBindingAliases, TestRegistryExamplesRecordTheirCode, TestUpgrade_ArgumentBinding, TestUpgrade_EveryRegistryExample and the workflow/template tests.
• Studio Pro-authored project: on two copies of TestApp (Mendix 11.14.0) exec'd the same script in canonical and in old spellings (microflow call, show page, show message/validation feedback/log templates, button actions, workflow call microflow): describe of the results is identical, and mxcli docker check on the canonical copy reports 0 errors.

🤖 Generated with Claude Code