MemberInitialiser and ConstructionExpression have no editable fields, so their name and type cannot be set from the editor

[matt-edmondson]

What happens

AstFields has no case for MemberInitialiser or ConstructionExpression. Both fall through to the _ => [] default in OfExpression (Coder.Graph/AstFields.cs:298), and TryWrite has no case for either, so it falls through to _ => false (Coder.Graph/AstFields.cs:443).

The consequence is that the inspector draws no rows at all for these two nodes, and the two scalar properties they own are unreachable:

• MemberInitialiser.Name (Coder/Ast/MemberInitialiser.cs:40) — which member is being initialised
• ConstructionExpression.Type (Coder/Ast/ConstructionExpression.cs:34) — the type being constructed

Both nodes are otherwise fully wired: AstSchema gives them slots and handles their children (Coder.Graph/AstSchema.cs:56-57, 88, 105, 171, 175, 260, 313, 366), and the YAML serializer round-trips both. So a document containing a constructor with an initialiser list, or any new Foo(...) expression, opens in the graph editor with nodes whose most important property is visible in the generated source and in the YAML but cannot be read or changed in the inspector.

Why it is a defect rather than a design choice

Every other node with a TypeReference property exposes it as a Text field carrying Type?.ToString(), relying on TypeReference.Parse/ToString being inverses:

• FieldDeclaration.Type — AstFields.cs:181
• ClassDeclaration.BaseType — AstFields.cs:190
• EnumDeclaration.UnderlyingType — AstFields.cs:158
• UsingAlias.AliasedType — AstFields.cs:177
• Parameter.Type — AstFields.cs:237
• FunctionDeclaration.ReturnType — AstFields.cs:215

ConstructionExpression.Type is the same shape and was simply not added. MemberInitialiser.Name is the same shape as every other Name text field.

Both node types were introduced in the 2026-09-10 run of AST work (699d4c6, e2f18b4), which added them to the AST, the schema, the serializer and all four generators — the inspector is the one projection that was missed.

Suggested fix

Add the two cases to OfExpression and the matching cases to TryWrite, following the existing pattern:

MemberInitialiser initialiser =>
[
    new("Name", AstFieldKind.Text, initialiser.Name ?? string.Empty),
],

ConstructionExpression construction =>
[
    new("Type", AstFieldKind.Text, construction.Type?.ToString() ?? string.Empty),
],

with the corresponding (MemberInitialiser initialiser, "Name") and (ConstructionExpression construction, "Type") write cases parsing back through TypeReference.Parse the way FieldDeclaration's does.

Rationale

Coder.Graph's stated contract is that the AST is the document and the graph is a view of it. A node the graph can hold, the schema can describe and the serializer can persist, but the inspector cannot edit, breaks that contract in the one direction the editor exists for. A user can construct these nodes by opening a file that contains them but then has to leave the editor and hand-edit YAML to change what type is constructed.

[matt-edmondson]

Triage: Priority: High · Effort: Small

MemberInitialiser.Name and ConstructionExpression.Type are fully wired into the AST, schema and serializer but have no AstFields case, so the inspector draws zero rows for either node — a user can only change them by leaving the editor and hand-editing YAML. Clear regression against the "AST is the document, graph is a view" contract this repo states explicitly.

Suggested next steps / acceptance criteria:

• Add the two missing cases to AstFields.OfExpression/TryWrite, following the existing TypeReference-as-Text-field pattern (FieldDeclaration.Type, ClassDeclaration.BaseType, etc.) — the issue body includes a ready-to-use snippet.
• ConstructionExpression.Type parses back through TypeReference.Parse on write, same as FieldDeclaration's.
• New Coder.Test coverage exercising the inspector round-trip for both node types.

Blockers/dependencies: None — this is the concrete instance that motivates the exhaustiveness test proposed in #49.

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Generated by Claude Code