Cleanup some C# warnings and dispose behavior. Make formatting more consistent.

.github/instructions/cs-debug-binding.instructions.md

@@ -3,26 +3,34 @@ description: Use when changing the C ABI (foundry_local_c.h) and validating C# t
 applyTo: sdk_v2/cs/**
 ---
 
-# C# Tests Auto-Load the C++ **Debug** Build
+# C# Tests Auto-Load the C++ **RelWithDebInfo** Build
 
 The C# project (`sdk_v2/cs/src/Microsoft.AI.Foundry.Local.csproj`) auto-detects
-`sdk_v2/cpp/build/Windows/Debug/bin/Debug/foundry_local.dll` for inner-loop dev
-and writes a `foundry_local.native.cfg` redirect file. The test project copies
-this redirect to its output, so `dotnet test` always loads the **Debug** native
-binary, never RelWithDebInfo.
+`sdk_v2/cpp/build/Windows/RelWithDebInfo/bin/RelWithDebInfo/foundry_local.dll`
+for inner-loop dev and writes a `foundry_local.native.cfg` redirect file. The
+test project copies this redirect to its output, so `dotnet test` always loads
+the **RelWithDebInfo** native binary. The auto-detect block only checks the
+RelWithDebInfo config (one entry per OS) — it never probes a Debug build.
+
+To override (e.g. point at a Debug build or a NuGet runtime package), set
+`FoundryLocalNativeBinDir` or `FoundryLocalRuntimeVersion` explicitly; otherwise
+the RelWithDebInfo auto-detect wins.
 
 ## Implication
 
 When you change the C ABI surface (e.g. `foundry_local_c.h`, struct layouts,
-function signatures in `c_api.cc`), you **must rebuild Debug** before running
-C# tests, even if you've already built RelWithDebInfo for the C++ test suite:
+function signatures in `c_api.cc`), you **must rebuild RelWithDebInfo** before
+running C# tests:
 
 ```powershell
 cd sdk_v2/cpp
-python build.py --build --config Debug
+python build.py --build --config RelWithDebInfo
 ```
 
-## Symptoms of a stale Debug DLL
+This is the same config the C++ integration test suite uses, so a single
+RelWithDebInfo build serves both.
+
+## Symptoms of a stale RelWithDebInfo DLL
 
 - C# tests fail with native errors that don't match current C++ source line numbers
 - Dispatch falls through unexpectedly (e.g. JSON pass-through stops working

memories/repo/cs-item-ownership-transfer.md

@@ -0,0 +1,13 @@
+# C# Item Ownership Transfer & CA2000
+
+- `Item : IDisposable` owns a native handle. Hand it to a container via the **generic** `ItemQueue.Push(Item)` or `Request.AddItem(Item)` — that is the only intended API.
+- **Do NOT add per-type push/add helpers** (`PushBytes`, `PushText`, etc.) — they don't scale. Use `queue.Push(BytesItem.CreateOwned(chunk))` inline instead.
+- Transfer order is leak-safe: native call first, then `item.ReleaseOwnership()` only on success (a throwing push under `using` won't leak).
+- **Owned** items (`CreateOwned`, `AudioItem.CreateFormatDescriptor`): `_pinContext` is **never assigned** (not "set to null on transfer" — the owned factories use a private ctor that only allocates the native handle, and keep the pin in a local). The pin lives behind a `GCHandle` and is freed by the native deleter (`BytesDeleter` → `PinContext.ReleaseFromNative`) when the native item is destroyed via `flItem_Release`.
+- Owned factories pin + root in one shot via **`PinContext.PinForNativeDeleter(data, out ptr, out len)`** (returns the `deleter_user_data` IntPtr). Do NOT pin-then-alloc as two separate locals in the factory — `PinForNativeDeleter` is the single ownership-transfer chokepoint and also guards the pin→GCHandle gap. New owned Item types should route through it.
+- `Item.Dispose()` does exactly two things: `OnDisposing()` then release-native-`if (_ownsHandle)`. For an owned item *after transfer* both short-circuit — `OnDisposing` runs `_pinContext?.Dispose()` (no-op, field is null) and `_ownsHandle == false` skips the native release. So Dispose is fully inert; whoever now owns the handle triggers the deleter. Disposing an owned item *before* pushing still cleans up correctly: `_ownsHandle == true` → `flItem_Release` → same deleter → unpin.
+- **Borrowed** items (`new BytesItem(ReadOnlyMemory)`, borrowed `AudioItem`) store the pin in `_pinContext` (no native deleter) and unpin in `OnDisposing` → unsafe to dispose after a queue push (native still references the buffer). For streaming/queue use the **owned** factories.
+- See `sdk_v2/cs/docs/item-data-ownership.md` (States 1-4) for the full pin/ownership model.
+- **CA2000 is intentionally disabled project-wide** via `<NoWarn>$(NoWarn);CA2000</NoWarn>` in both csprojs (+ `.editorconfig` severity `none`). It can't model ownership transfer and fires false positives on every hand-off. **IDisposableAnalyzers** (SDK project, `PrivateAssets=all` so it doesn't flow to tests) is the disposal-correctness authority. Do NOT re-add CA2000 pragmas or per-site suppressions.
+- **IDISP001** (IDisposableAnalyzers) follows data flow into *same-assembly* callees, so passing a created disposable to a helper that roots it in a `GCHandle` (instead of disposing/returning it) does NOT suppress the warning — the analyzer fundamentally can't model ownership handed to unmanaged code freed by a native callback. The single justified `#pragma warning disable IDISP001` lives at the one transfer boundary in `PinContext.PinForNativeDeleter`; do not scatter suppressions across the owned factories.
+

sdk_v2/cpp/src/spdlog_logger.cc

@@ -73,7 +73,20 @@ SpdlogLogger::SpdlogLogger(LogLevel min_level, const std::string& logs_dir) {
                                                    spdlog::async_overflow_policy::block);
 
   logger_->set_level(ToSpdlogLevel(min_level));
-  logger_->flush_on(spdlog::level::warn);
+
+  // Flush policy: by default we buffer low-severity logs and only force a flush at warning and
+  // above (plus on destruction), avoiding a per-message flush on the hot path. We flush on every
+  // message only when running in a debug build, or when the caller has explicitly opted into
+  // Debug/Verbose diagnostics -- in those cases prompt, crash-safe output is worth the cost.
+#ifndef NDEBUG
+  constexpr bool debug_build = true;
+#else
+  constexpr bool debug_build = false;
+#endif
+
+  const bool flush_every_message = debug_build || min_level <= LogLevel::Debug;
+
+  logger_->flush_on(flush_every_message ? spdlog::level::trace : spdlog::level::warn);
 
   spdlog::register_logger(logger_);
 }

sdk_v2/cs/.editorconfig

@@ -300,8 +300,12 @@ dotnet_diagnostic.IDE0090.severity = error
 ## Suppressing this particular case due to issues in the analyzer's understanding of pattern matching.
 dotnet_diagnostic.IDE0072.severity = suggestion
 
-# CA2000: Dispose objects before losing scope
-dotnet_diagnostic.CA2000.severity = warning
+# CA2000: Dispose objects before losing scope.
+# Downgraded to 'none' — see the NoWarn + rationale in the .csproj files. The Item ownership model
+# transfers a native handle into a container (Request/ItemQueue) and the C# wrapper's Dispose() is a
+# no-op afterwards (docs/item-data-ownership.md), which CA2000 can't model. IDisposableAnalyzers is
+# our authority for disposal correctness instead.
+dotnet_diagnostic.CA2000.severity = none
 
 # IDE0046: Convert to conditional expression
 dotnet_diagnostic.IDE0046.severity = silent

sdk_v2/cs/src/Catalog.cs

@@ -6,7 +6,6 @@
 
 namespace Microsoft.AI.Foundry.Local;
 
-using System;
 using System.Collections.Generic;
 using System.Threading.Tasks;
 

sdk_v2/cs/src/Detail/DllLoader.Modern.cs

@@ -1,4 +1,4 @@
-// --------------------------------------------------------------------------------------------------------------------
+// --------------------------------------------------------------------------------------------------------------------
 // <copyright company="Microsoft">
 //   Copyright (c) Microsoft. All rights reserved.
 // </copyright>
@@ -12,6 +12,7 @@
 namespace Microsoft.AI.Foundry.Local.Detail;
 
 using System.Runtime.InteropServices;
+
 using Microsoft.AI.Foundry.Local.Detail.Interop;
 
 internal static partial class DllLoader

sdk_v2/cs/src/Detail/DllLoader.NetStandard.cs

@@ -1,4 +1,4 @@
-// --------------------------------------------------------------------------------------------------------------------
+// --------------------------------------------------------------------------------------------------------------------
 // <copyright company="Microsoft">
 //   Copyright (c) Microsoft. All rights reserved.
 // </copyright>
@@ -16,6 +16,7 @@
 namespace Microsoft.AI.Foundry.Local.Detail;
 
 using System.Runtime.InteropServices;
+
 using Microsoft.AI.Foundry.Local.Detail.Interop;
 
 internal static partial class DllLoader

sdk_v2/cs/src/Detail/DllLoader.cs

@@ -1,4 +1,4 @@
-// --------------------------------------------------------------------------------------------------------------------
+// --------------------------------------------------------------------------------------------------------------------
 // <copyright company="Microsoft">
 //   Copyright (c) Microsoft. All rights reserved.
 // </copyright>
@@ -7,6 +7,7 @@
 namespace Microsoft.AI.Foundry.Local.Detail;
 
 using System.Runtime.InteropServices;
+
 using Microsoft.AI.Foundry.Local.Detail.Interop;
 
 /// <summary>