[matt-edmondson]

Requested by Matt · project thread

This PR carries seven changes, one commit each.

ImGui 3.75 / UndoRedo 3 (supersedes #277)

Before: the editor stays on ktsu.ImGui.NodeEditor 3.38.5. Dependabot's bump (#277) fails with CS0433. NodeEditor 3.75 brings in ktsu.UndoRedo 3.4, which absorbed ktsu.UndoRedo.Core, so every undo type reached the editor's compilation twice.

After: NodeEditor is at 3.75.3, and the editor references ktsu.UndoRedo 3.4.0 in place of ktsu.UndoRedo.Core 1.1.4.

How: the namespaces and API did not change, so this is a package swap in Directory.Packages.props and the editor's csproj, with no code edits.

A failed save keeps the last save (fixes #292)

Before: SchemaFile.TrySave wrote over the target with File.WriteAllText, which truncates the file before writing. A write that failed partway, such as on a full disk or a dropped network share, left the only saved copy empty or partial, and the editor's memory held the only intact copy.

After: the target holds either the complete previous save or the complete new one, and a failed save leaves nothing behind in the folder.

How: the JSON is written to <name>.tmp-<guid> beside the target. It is then swapped in with File.Replace, or with File.Move when there is no existing file to replace. The temporary file is deleted on any failure. An internal overload takes the write step as a delegate, so three new tests can make it fail partway and check that the original bytes are unchanged and no temporary file remains. The optional SchemaGenerator.GenerateToDisk change is left out, because generated output can be regenerated.

A file the model cannot read is refused, not loaded empty (fixes #278)

Before: a PascalCase or legacy file ({"Classes": [...]}) loaded as an empty schema and reported "Migrated from format version 0". Validation passed, and saving from the editor replaced the file with nothing.

After: SchemaSerializer.Load returns InvalidJson for any root property the model does not read. When the only problem is casing, the message names the camelCase spelling, for example 'Classes' would be 'classes'. A file from a newer format version is still reported as newer, because the version check runs first.

How: the known names come from the serializer's own JsonTypeInfo for Schema, so a property added to the model is accepted as soon as it can be read. The new tests check that every committed legacy sample is refused and every modern sample still loads. docs/schema-format.md documents the refusal.

A null in the C++ options file is refused, not thrown (fixes #291)

Before: kschema --cpp-options threw a NullReferenceException for {"existingTypes": null} or {"existingTypes": {"Kilograms": null}}, and the error did not point at the file.

After: both are refused with a message naming the key. A null for any other value the options need, such as generatedBy or a spelling's include, is also refused.

How: CppGeneratorOptionsFile sets RespectNullableAnnotations, so the deserializer refuses nulls in non-nullable properties. Dictionary values fall outside that setting, so IsSpelled checks for a null entry itself. Six new tests cover these cases.

A discriminator out of position loads, and a missing one is refused (fixes #287)

Before: a type written as { "quantityName": "Mass", "TypeName": "Quantity" }, or a default with DefaultKind after value, threw NotSupportedException out of SchemaSerializer.Load. A type with no recognised discriminator ({} or { "typeName": "Int" }) threw the same exception, so kschema validate crashed instead of reporting the file.

After: the discriminator can appear anywhere in its object. A type without one is reported as InvalidJson, and the CLI says "Could not open".

How: SchemaSerializer.JsonOptions sets AllowOutOfOrderMetadataProperties, and Load also catches NotSupportedException, which is how the serializer reports a polymorphic shape it cannot construct. Four new tests cover these cases.

A null in a hand-written schema no longer throws (fixes #242)

Before: "classes": null, "members": null, a null class name or a null member type loaded "successfully" and then threw a NullReferenceException from Validate(), the editor or a generator. A null list element, such as "classes": [null], did the same.

After: a null property reads exactly as if it were omitted, which is what the serializer already writes, so the default (an empty list, an empty name, None) takes over and validation reports anything that is then incomplete, such as "empty name". A null element in a list is refused as InvalidJson, with its path in the message, for example $.classes[0].members[0]. The CLI says "Could not open".

How: Load parses the document into a JsonNode, removes null properties and stops at the first null array element, then deserializes from the node. Nothing in the model is a dictionary or extension data, so "null means omitted" holds everywhere. Thirteen new tests cover these cases, and docs/schema-format.md documents the rule.

A class that holds itself by value is an error (fixes #293)

Before: a class holding itself, directly (TreeNode.Parent : TreeNode) or through other classes, an Optional or a Result, validated cleanly. It has no finite size, so no generator could produce a type that compiles.

After: validation reports one error per cycle, at the member that closes it, naming the route (A.b → B.c → C.a → A) and suggesting an Array or a Handle, which is how a recursive structure is meant to be written. A reference through an Array, Handle or Interface is not a cycle, and neither is a diamond.

How: a depth-first walk over the classes each member holds by value, which visits each class once, so a cycle is reported once rather than once per class on it. The existing test for two travelsAsBytes classes holding each other now expects this error. Six new tests cover these cases, and disabling the report fails five of them.

The build is clean and all 544 tests in Schema.Test pass on net10.0 locally.

🤖 Generated with Claude Code

https://claude.ai/code/session_01B1AYPNe9rDK8FtuQgiKTnT

[sonarqubecloud]

Quality Gate passed

Issues
9 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

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