SqlBulkCopy works end-to-end over the TDS endpoint for SqlClient 6.x and 7.x: the metadata pre-batch parses via four general engine fixes (SET FMTONLY as session state returning schema-only zero-row results, leading-empty-segment names like ..proc and .[sys].[all_columns], sp_tablecollations_100 as a modeled system proc, bare SELECT TOP n *), INSERT BULK and the BulkLoadBCP packet decode client COLMETADATA + rows into the normal storage path (FIXEDLENTYPE tokens raw, decimals as sign + fixed 16-byte mantissa whose length byte only flags NULL), and probed bulk semantics land exactly: CHECK/FK skipped-and-untrusted by default vs enforced-and-trusted with CHECK_CONSTRAINTS, PK/UNIQUE/NOT NULL always enforced, triggers gated on FIRE_TRIGGERS, KeepIdentity/KeepNulls defaults, computed/rowversion server-generated, external-transaction rollback undoing the load.

Author: RyanLamansky

CLAUDE.md

@@ -164,7 +164,7 @@ Per-feature deep-dives live under `docs/claude/`. Each entry below is a trigger:
 - **New top-level statement parser or dispatch-loop separator rules, double-quoted identifiers / QUOTED_IDENTIFIER** → [`grammar.md`](docs/claude/grammar.md) + [`control-flow.md`](docs/claude/control-flow.md).
 - **BACPAC import** (`Simulation.ImportBacpac` — multi-database via repeated calls, `BacpacImportOptions`, `ModelXmlReader` dispatcher, BCP wire format, `BacpacBuilder` test harness) → [`bacpac-loader.md`](docs/claude/bacpac-loader.md).
 - **Linked servers** (`Simulation.AddRemoteSimulation`, `sp_addlinkedserver` / `sp_dropserver`, four-part FROM routing through the remote's ADO.NET pipeline, `OPENQUERY(server,'query')` ad-hoc pass-through + compile-time schema discovery, `sys.servers`) → [`linked-servers.md`](docs/claude/linked-servers.md).
-- **TDS network endpoint** (`Simulation.ListenAsync` → `SimulatedNetworkListener`; real SqlClient over loopback TCP+TLS; SQLBatch/RPC/TM, no bulk; `sp_cursor*` API-server-cursor RPC family; credential enforcement via the `CREATE LOGIN` registry, Msg 18456 on mismatch; EF via plain `UseSqlServer`; oracles = `*.Tests.SqlClient` + `*.Tests.Smo`, the real-SMO consumer oracle) → [`tds-endpoint.md`](docs/claude/tds-endpoint.md).
+- **TDS network endpoint** (`Simulation.ListenAsync` → `SimulatedNetworkListener`; real SqlClient over loopback TCP+TLS; SQLBatch/RPC/TM/BulkLoad (`SqlBulkCopy`); `sp_cursor*` API-server-cursor RPC family; credential enforcement via the `CREATE LOGIN` registry, Msg 18456 on mismatch; EF via plain `UseSqlServer`; oracles = `*.Tests.SqlClient` + `*.Tests.Smo`, the real-SMO consumer oracle) → [`tds-endpoint.md`](docs/claude/tds-endpoint.md).
 
 ## Not modeled
 

SqlServerSimulator.Tests.SqlClient/BulkCopyTests.cs

@@ -37,9 +37,10 @@ public static void ExecInProc(Simulation simulation, string sql)
     }
 
     /// <summary>
-    /// Inserts through the in-process surface with one bound parameter. The wire
-    /// listener does not yet accept RPC / parameterized commands, so large or
-    /// binary payloads seed via ADO here, then read back over the wire.
+    /// Inserts through the in-process surface with one bound parameter — a
+    /// convenience for seeding large or binary payloads in-proc before reading
+    /// them back over the wire (the wire path accepts RPC / parameterized
+    /// commands too; this just keeps seeding terse).
     /// </summary>
     public static void ExecInProcParam(Simulation simulation, string sql, string parameterName, object value)
     {

SqlServerSimulator.Tests.SqlClient/Wire.cs

@@ -50,6 +50,10 @@ internal static partial class BuiltInResources
         "xp_msver",
         "xp_qv",
         "xp_instance_regread",
+        // sp_tablecollations_100: SqlClient's SqlBulkCopy metadata batch calls
+        // it (`exec ..sp_tablecollations_100 N'[schema].[table]'`) to read the
+        // destination columns' TDS collation structures before streaming rows.
+        "sp_tablecollations_100",
     ];
 
     /// <summary>

SqlServerSimulator/BuiltInResources.LegacyCompat.cs

@@ -2,7 +2,7 @@
 
 Auto-loaded when working in this directory. The behavior deep-dive is [`docs/claude/tds-endpoint.md`](../../docs/claude/tds-endpoint.md) — protocol scope, response shapes, divergences, deferred items. These notes are the local implementation contracts.
 
-- **Session layout**: `TdsSession` is a partial — main file (prelogin/TLS/login/batch loop + `StreamOutcomesAsync`), `.Rpc.cs` (RPC dispatch + prepared-handle map + `WellKnownProcId` name/id map), `.Cursors.cs` (the `sp_cursor*` API-server-cursor family), `.TransactionManager.cs` (TM requests + the session `transaction` field).
+- **Session layout**: `TdsSession` is a partial — main file (prelogin/TLS/login/batch loop + `StreamOutcomesAsync`), `.Rpc.cs` (RPC dispatch + prepared-handle map + `WellKnownProcId` name/id map), `.Cursors.cs` (the `sp_cursor*` API-server-cursor family), `.TransactionManager.cs` (TM requests + the session `transaction` field), `.BulkLoad.cs` (the `SqlBulkCopy` handshake: `INSERT BULK` detect/parse-ack + BulkLoadBCP packet decode via `TdsBulkLoadReader`, feeding `Simulation.ExecuteBulkInsert`).
 - **API server cursors** (`.Cursors.cs`): `sp_cursoropen/fetch/close/prepexec/execute/prepare/unprepare/option` + `sp_cursor` positioned DML. Each handle in the per-session `apiCursors` map wraps an engine `Cursor` **registered under an opaque `sss_apicursor_<n>` name in `connection.Cursors`** (so `WHERE CURRENT OF` resolves it) — built by synthesizing `DECLARE … CURSOR … FOR <stmt>; OPEN` and reusing the engine's sensitivity resolution. Fetch drives `Cursor.Fetch` directly per row over a throwaway `BatchContext` (its command needs a non-empty `CommandText` — `" "` — or `ParserContext` throws); positioned DML sets `Cursor.CurrentRid` to a buffered RID then runs synthesized `UPDATE/DELETE … WHERE CURRENT OF`. **Prepared/parameterized cursors freeze their bound params on the ApiCursor and re-apply them to every fetch batch** — a keyset/dynamic cursor re-runs its SELECT per fetch, so the fresh batch would otherwise miss the variables. Result sets append a trailing `ROWSTAT` int column. Concurrency options (SCROLL_LOCKS/OPTIMISTIC) are echoed but not wired (probe-confirmed API-cursor optimistic conflicts don't surface). Contract + probed constants in [`docs/claude/tds-endpoint.md`](../../docs/claude/tds-endpoint.md). One task per socket; teardown is socket-close-driven; the catch list in `RunAsync` is the session's crash boundary — an exception type not listed there kills the session silently (client sees a transport error), so wire-format parse failures must throw `InvalidDataException`, unsupported features `NotSupportedException` (converted to ERROR tokens in handlers, never leaked).
 - **Validate before emitting**: any per-column rejection (`TdsTypeCodec.ValidateSchema`) must fire *before* COLMETADATA bytes are written — a throw mid-token desyncs the stream, which surfaces client-side as a corrupted-frame/transport error, not a useful message.
 - **Token writer contract**: `TdsTokenWriter` buffers synchronously; `FlushAsync(final: false)` after every row keeps memory bounded to max(row, packet). Only the final flush sets EOM. Tokens may legally split across packet boundaries.