ADR-0011: .NET edges come from built assemblies and portable PDBs, not C# source

• Status: Accepted
• Date: 2026-09-20
• Derives from: design.md § Prior art, § What each extractor has to get right (.NET), § Where it would be ignored (the build requirement), § Open questions (.NET Framework)
• Constrains: architecture.md § Extractors
• Implemented by: Wave 0 plan, Wave 2 plan, Wave 3 plan (--mode source)

Context

All three .NET architecture tools read compiled assemblies, because the compiler has already resolved every reference; there is no path-alias problem to reimplement. The reference set is wider than using: a body call, a generic instantiation, an attribute, a base type, an interface, a parameter type and a typeof are all edges.

Decision

• The .NET extractor reads the built assemblies' ECMA-335 metadata tables and IL operands for the edge set, and the portable PDB's Document and MethodDebugInformation tables to map every type and method to a source file and line.
• A type is not a file. A type's fields and attributes are attributed to the document of its first constructor or first method. A type with no methods and no PDB row is attributed by naming convention and flagged attribution: inferred; a type with no attribution at all reports attribution: none, and path-based rules skip it with a warning.
• Every edge carries a dependencyKind from inherits, implements, field, signature, body, attribute, generic-argument, typeof.
• A solution with no built assemblies, or a PDB that is not portable, makes the run untrustworthy (exit 2, ADR-0008). DebugType=portable is the SDK default; the wave 0 spike measures how many .NET Framework projects in the test beds need it set.
• Compiled mode is the gate. A source mode (--mode source, tree-sitter-c-sharp, namespace-level, marked approximate) is the inner-loop form and lands in wave 3; it never replaces compiled mode in CI.

Consequences

• A .NET pipeline adds a build step it already has.
• Path matchers work on .NET because the PDB gives every type a file, which is what makes one rule language span three languages.

Alternatives considered

• Roslyn over source. Rejected as the primary: it requires the .NET runtime, and the IL view is what ArchUnitNET's vocabulary (calls, body dependencies) needs. Kept as the wave 3 Roslyn analyzer front-end, which reports the same rules where agents already look.