C# generation API and diagnostics

CSharpGenerator.Generate(VersionedModel, GenerationOptions, CancellationToken) is synchronous and has no file, process, configuration or compiler dependency. GenerationOptions.LanguageVersion accepts numeric 14 or 15; the default is 14. Compiler release channel is chosen by the caller independently.

The existing GenerationOptions record and three-argument entry point are unchanged. To choose an emitted namespace, call NamespaceOverride.TryCreate(string). It returns Result<NamespaceOverride, GenerationDiagnostic>; a successful immutable value exposes Value. Pass it to CSharpGenerator.Generate(model, options, namespaceOverride, cancellationToken). Both overloads use the same core implementation. An override applies to the input Library package and all its qualified type, value and constructor references. Package-derived source paths and the original typed IR remain unchanged. Separate or concurrent requests never share naming state.

The namespace accepts dotted literal BMP C# identifiers in Unicode Normalization Form C, including @-escaped reserved words. It admits the identifier character categories defined by the C# lexical specification. Formatting characters retain their literal spelling and have the compiler’s identifier-equivalence behavior. Source \u/\U escape syntax and surrogate characters are outside this literal-name boundary. Values are validated rather than normalized or interpreted as source text. Null, empty, malformed and injection-like input returns invalid-namespace at $options/namespace. An explicit null/default namespace value from a C# caller to the four-argument overload returns that same located refusal and no sources. An already cancelled caller still receives Cancelled first.

GenerationResult returns Status, Family, exact SourceVersion, selected LanguageVersion, Sources, Diagnostics and Runtime. Each source has RelativePath and Text. The runtime requirement is net10.0 plus the public Morphir.SDK.CSharp package. The core package itself does not reference that runtime. Consumers must resolve a runtime implementing the frozen SDK contract.

Success returns the complete source set and no diagnostics. Failure returns the first located refusal and no sources. Cancelled returns no sources or diagnostics, retaining input family/version and the selected profile. A caller that needs exception-based cancellation can translate this status at its edge. Cancellation checks cover traversal and emission, with a final token check before success. Invalid later modules also discard all earlier generated text.

Diagnostics carry stable Rule, structural Location and human-readable Message fields. Locations identify the version/options/distribution or the package/module/type/value/pattern/expression being checked. Callers should branch on Rule, not parse messages. The CLI successor can map these categories without loading a compiler or changing core semantics.

Diagnostic identities use explicit structural spellings, for example Name["car","rental"], ModulePath[Name["inventory"]] and FQName(PackagePath[Name["example"]],ModulePath[Name["data"]],Name["person"]). Raw words and path segments remain distinguishable. Strings are quoted, quotes and backslashes are escaped, null strings are written null, and control or surrogate characters use \u followed by four hexadecimal digits. Type mismatch messages describe Parameter(Name[...]), Named(FQName(...),[...]), Product([...]), Fields[Name[...]:...,Name[...]:...], Arrow(...,...) or Unit. These diagnostic-only spellings avoid structural reflection in NativeAOT. Module validation locations now use $modules/ModulePath[...]. This intentionally changes diagnostic text and that location spelling while retaining rule IDs, refusal and cancellation behavior, generated source bytes and paths. Callers should continue branching on Rule rather than parsing human messages.

Unknown dependencies and SDK operations fail explicitly. No object-erased value, runtime stub or success-shaped partial artifact substitutes for a refusal. Admitted value-dependent SDK failures, such as checked overflow, remain execution errors. An admitted non-exhaustive source pattern raises pattern failure when no branch matches; every branch is still checked during generation.

Generated records/cases have get-only payloads and explicitly implement the SDK structural equality/hash protocol. That protocol alone does not establish the physical immutability of arbitrary externally supplied CLR generic payloads. The tested Morphir inputs use the admitted typed representations and immutable SDK collections. No arbitrary CLR IEquatable or reflection fallback is emitted.

See usage, host matrix and fixture scope and the generate command. The production AdditionalFiles/config/incremental adapter remains deferred.