Copilot instructions

1---
2applyTo: "src/native/managed/cdac/**,docs/design/datacontracts/**,src/coreclr/**/datadescriptor/**"
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4 
5# cDAC — Folder-Specific Guidance
6 
7## Preface
8 
9The instructions under `API Review`, `DacDbi interface` and `Dump compatibility` only apply if the SDK version in global.json is a preview, release candidate or otherwise a development branch of .NET 11. If this is a development branch of .NET 12 or later, you **MUST** ignore these three sections entirely. Check `global.json` before applying them.
10 
11## API Review (.NET 11 dev branches only)
12 
13New APIs on implementations of IContract under the folder src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/** do **NOT** need to go through API review. **MUST NOT** describe such changes as "breaking" or "public API changes".
14 
15## DacDbi interface (.NET 11 dev branches only)
16 
17The DacDbi COM interface is **internal and unstable**.
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19- **MUST NOT** flag changes to DacDbi as breaking changes.
20- **MUST NOT** warn about COM ABI compatibility, vtable ordering, or
21  GUID changes on DacDbi.
22 
23## Dump compatibility (.NET 11 dev branches only)
24 
25- **MUST NOT** raise concerns about older dumps lacking new data descriptors.
26- **MUST NOT** request fallback paths, conditional reads, or versioning
27  shims for missing descriptors on the grounds of "supporting older dumps".
28 
29## Exception types (ALL branches)
30 
31When porting `HRESULT`-returning APIs to throw exceptions, the following mappings **MUST** be accepted:
32- `ArgumentException` → for `E_INVALIDARG`
33- `NullReferenceException` → for `E_POINTER`
34- `InvalidCastException` → for `E_NOINTERFACE`
35 
36## Documentation updates (ALL branches)
37 
38`docs/design/datacontracts/<Name>.md` is the authoritative spec of each contract (1:1 with `Abstractions/Contracts/I<Name>.cs`). If the PR changes any of the following without also updating the doc, **MUST** flag it as an error citing the exact doc file:
39 
40- **`Abstractions/Contracts/I<Name>.cs`** — added, removed, or renamed methods, or new exposed types/enums.
41- **`Contracts/Contracts/<Name>_<N>.cs`** — a new version file (needs a new `## Version N` section), or a semantic change to an existing version's algorithm. Pure refactors don't need doc updates.
42- **New contract** (new `I<Name>.cs` + `<Name>_1.cs`) — needs a new `docs/design/datacontracts/<Name>.md`.
43- **`src/coreclr/**/datadescriptor/**`** — added, removed, or renamed types, fields, or globals may need a matching update in every consuming contract's doc; check whichever contracts' algorithms are affected.
44 
45Do **NOT** require doc updates for pure refactors, test-only changes, bug fixes that restore documented behavior, `Legacy/**` (SOSDacImpl, DacDbi shim), or build/CI changes.
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