modelsdk codec writes Integer fields (canvas/popup dimensions) as BSON int32, not int64

[ako]

Summary

The modelsdk codec engine serializes Mendix Integer properties as BSON int32, but Studio Pro (and the legacy MPR writer) store these as int64. The mismatch is tolerated by mx check today, but it produces type-inconsistent BSON: codec-written pages differ from Studio-Pro-written pages, and within a single page the CREATE path (codec, int32) disagrees with the page-mutator ALTER path (raw BSON, int64).

Surfaced while implementing pop-up dimensions for #661 — the codec write path was the one place that couldn't match Studio Pro's on-disk type.

Evidence

Fresh 11.11.0 project, two pages created via mxcli, dumped with mxcli bson dump --format bson:

Field	Studio Pro / legacy writer	modelsdk codec
CanvasWidth / CanvasHeight	int64	int32
PopupWidth / PopupHeight	int64	int32

Both pass mx check (0 errors), so this is correctness/consistency hygiene, not a build break.

Root cause

modelsdk/property/primitive.go — BSONValue() returns Get(), so a Primitive[int32] serializes as int32:

func (p *Primitive[T]) BSONValue() any { return p.Get() }

The gen types bind these fields as int32 (engalar's generator maps reflection Integer → int32), e.g. modelsdk/gen/pages/types.go:

o.canvasWidth = property.NewPrimitive[int32]("CanvasWidth", property.DecodeInt32)
o.popupWidth  = property.NewPrimitive[int32]("PopupWidth",  property.DecodeInt32)

The read side already knows the truth — property.DecodeInt32's own doc comment:

Mendix/Studio Pro stores small integers (connection indices, canvas positions, …) as BSON int64 — and occasionally as double — not int32, so accept all three numeric encodings.

So the decoder tolerates int64 on read; only the encoder emits the wrong width. This is the same gen storage concern noted previously for canvas/popup.

Scope / blast radius

This affects every Integer-typed gen field across all document types (canvas/popup dimensions, microflow connection indices, positions, etc.) — not just pages. That breadth is exactly why it was kept out of the #661 PR.

Options

1. Encoder-level (broadest, cleanest): make Primitive[int32].BSONValue() emit int64. Aligns all Integer fields with Studio Pro in one place; the decoder already round-trips int64. Needs validation that no consumer/round-trip test asserts int32 on the serialized side.
2. Codegen type mapping: map reflection Integer → an int64-emitting primitive in engalar's generator and regenerate modelsdk/gen/**. More faithful to the metamodel but touches the generator toolchain.
3. Per-field override: force int64 for a known list of dimension fields only. Narrowest, but a manually-maintained list (maintenance risk) and leaves other Integer fields inconsistent.

Recommend option 1 or 2 (whole-class fix) over 3.

Acceptance

• modelsdk codec writes Integer fields as BSON int64 (canvas + popup at minimum).
• A codec-created page's CanvasWidth/PopupWidth BSON type matches a Studio-Pro-authored page byte-for-type.
• CREATE (codec) and ALTER (mutator) produce the same type for popup dimensions.
• mx check stays green across doc types; round-trip tests updated for int64.

References

• modelsdk/property/primitive.go (BSONValue, DecodeInt32)
• modelsdk/gen/pages/types.go (canvas/popup bindings)
• The Pop-up width / Pop-up height of a Page are not managed #661 (pop-up dimensions — where CREATE codec int32 vs ALTER int64 surfaced)
• .claude/skills/fix-issue.md (symptom-table row for The Pop-up width / Pop-up height of a Page are not managed #661 notes the int32/int64 split)

[github-actions]

Issue Triage

Summary:
The mxcli codec serializes Mendix Integer properties as BSON int32 while Studio Pro (and the legacy MPR writer) store them as int64, causing type‑inconsistent BSON output.

Checklist for bug report completeness

Required info	Present?	Details
mxcli version	❌	Not mentioned
Mendix version	✅	“Fresh 11.11.0 project”
Scenario (what the user was trying to do)	✅	Creating pages via mxcli and inspecting BSON with mxcli bson dump
Expected output	✅	Integer fields should be written as BSON int64, matching Studio Pro
Experienced output	✅	Codec writes int32; mx check passes but BSON types differ
AI bug report (mxcli diag --bundle or session log)	❌	Not provided

What’s missing:

• The exact version of mxcli you used (output of mxcli --version or commit/build info).
• A diagnostic bundle or session log from mxcli diag --bundle (or at least the relevant session log) to help reproduce the environment.

Could you please add those details? Once we have them, we’ll be able to investigate the inconsistency more effectively. Thanks for the thorough description!

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[github-actions]

Enhancement Implementation Guide

Completeness Assessment

The issue is well-detailed with clear evidence, root cause analysis, scope, and options. No additional questions are needed.

Overlap Check

This is an internal consistency fix in the modelsdk codec, not an MDL syntax feature. No existing MDL syntax or CLI command can address this BSON type mismatch. The fix requires changes to the modelsdk library's BSON serialization logic.

Proposed MDL Syntax

No MDL syntax change is required. This is an internal fix to the modelsdk codec's BSON serialization behavior for Integer properties. The MDL language remains unchanged.

Implementation Roadmap

1. Modify modelsdk/property/primitive.go:

   • Update the BSONValue() method for Primitive[T] to serialize int32 values as int64 in BSON while leaving other types unchanged:

     func (p *Primitive[T]) BSONValue() any {
         switch v := p.Get().(type) {
         case int32:
             return int64(v)
         default:
             return v
         }
     }

   • Why this works: The decoder (DecodeInt32) already accepts int64 input (per its doc comment), so this change only affects encoding. Other primitive types (bool, string, float64, etc.) pass through unchanged.

2. Update generated code bindings (if necessary):

   • Verify that modelsdk/gen/**/types.go still uses property.NewPrimitive[int32] for Integer fields. No change needed here—the fix is in the encoder, not the type binding.

3. Update test expectations:

   • Identify tests that assert BSON output for Integer fields (e.g., in sdk/mpr/ or mdl-examples/).
   • Change expected BSON type from int32 to int64 for fields like CanvasWidth, PopupWidth, ConnectionIndex, etc.
   • Focus on round-trip tests (write via mxcli → read back → verify values unchanged).

4. Run validation:

   • Execute make test to ensure all tests pass.
   • Verify with mx check on test projects that the BSON type inconsistency is resolved.
   • Confirm CREATE (codec) and ALTER (mutator) paths now produce matching int64 BSON for popup dimensions.

BSON Investigation

1. Key structures to verify:

   • Page document BSON: Check CanvasWidth, CanvasHeight, PopupWidth, PopupHeight under $type: "pages$Page".
   • Microflow activity BSON: Check ConnectionIndex in activities like SequenceFlow ($type: "microflows$SequenceFlow").
   • General pattern: Any Integer-typed field in generated metamodel.

2. Investigation steps:

   • Create a test Mendix 11.11.0 project with a page and microflow.
   • Use mxcli bson dump --format bson to inspect raw BSON before/after fix.
   • Compare with Studio Pro-generated BSON (create same page/microflow in Studio Pro, dump via mx).
   • Focus on the modelsdk/property/primitive.go change point: verify int32 → int64 conversion only affects encoding.

3. Reference data:

   • Check reference/mendixmodellib/reflection-data/ for Integer property definitions (should specify BSON type as Long/int64 in Studio Pro).
   • Confirm no default value conflicts (Integer properties rarely have non-zero defaults).

Testing Strategy

1. Doctype test scripts:
   • Add to mdl-examples/doctype-tests/01-page-examples.mdl:

     create page Test.Page (
         CanvasWidth: 800,
         CanvasHeight: 600,
         PopupWidth: 400,
         PopupHeight: 300
     );
     

   • Add to `mdl-examples/doctype-tests/03-microflow-ex

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