mxcli diff reports false deletions (java-action calls, download, grant, geometry) on an UNMODIFIED describe dump — and leaks Go struct pointers into retrieve constraints

[MohamedGamalEzzatAli]

mxcli version: v0.20.0 (release 2026-08-28) · Mendix 11.12.1 bench project

mxcli diff against the unmodified output of mxcli describe claims the script would delete activities that the executor demonstrably round-trips byte-identically. The diff's script-side model appears to drop what it cannot represent — and its constraint rendering leaks a Go struct pointer (%v formatting).

Repro

Any microflow containing java-action calls, a download file, and a grant execute (mine: 23 activities, 4 java-action calls incl. CommunityCommons.Base64EncodeFile):

mxcli describe microflow MyModule.ACT_GenerateDocument -p App.mpr --format mdl > dump.mdl
mxcli diff dump.mdl -p App.mpr

Observed

Summary: 0 new, 1 modified, 0 unchanged — with the "modification" being (sanitized excerpt, structure verbatim):

--- Microflow.MyModule.ACT_GenerateDocument (current)
+++ Microflow.MyModule.ACT_GenerateDocument (script)
-  @start(-2045, 200)
-  @position(-1905, 200)
-  @curve(from: (30, 0), to: (-30, 0))
   ...every geometry annotation shown as deleted...
-    where index=0
-    limit 1;
+      where &{0x236139b542d0 index=0}
+      limit 1;
-  $returnedbase640 = call java action CommunityCommons.Base64EncodeFile(file = $Image0);
-  $returnedbase64_1 = call java action CommunityCommons.Base64EncodeFile(file = $Image1);
-  $GeneratedDocument = call java action MyModule.GenerateDocument(WorldDocument = $WorldDocument, WorldTemplate = $NewTemplate);
-  $generatedpdf = call java action MyModule.ConvertToPdf(DocxDocument = $GeneratedDocument, pdfFileName = 'Generated-pdf.pdf');
-  download file $generatedpdf;
-
-grant execute on microflow MyModule.ACT_GenerateDocument to MyModule.User;

Three distinct symptoms:

1. False deletions — every call java action, the download file, the trailing grant execute, and all @position/@curve/@start lines render as - with no + counterpart.
2. Pointer leak — retrieve constraints re-render as where &{0x236139b542d0 index=0} instead of where index=0 (looks like %v on the constraint struct).
3. Misleading summary — 0 new, 1 modified reads as a minor tweak while the body implies the flow would be gutted.

Control — the executor is fine

mxcli exec dump.mdl -p App.mpr        # "Replaced microflow: MyModule.ACT_GenerateDocument"
mxcli describe microflow MyModule.ACT_GenerateDocument -p App.mpr --format mdl > post.mdl
diff dump.mdl post.mdl                # (OS diff) → BYTE-IDENTICAL

So exec parses and re-emits every construct that diff claims would vanish — java actions, download, grant, geometry included. The round-trip is lossless; only diff's script-side parse/render is broken.

Impact

diff is the natural pre-apply safety gate for exactly this workflow (describe → tweak → diff → exec). False deletion reports either block perfectly safe applies or teach users to ignore the gate. We carried a "describe→exec round-trip is lossy" belief for a month on this evidence before the exec control disproved it.

Expected

diff shares the executor's script parser/renderer (or diffs at the parsed-model level), and constraint rendering uses the constraint's MDL string form rather than struct %v.