M3 R3.1: map the required non-streamed write sequence (OpenStorageConnection is the missing step)

Static decompile mining of the 2023 R2 client corroborates the live R3.1 error:
the AddNonStreamValues failure is the missing StorageService.OpenStorageConnection,
which creates exactly the \.\pipe\aahStorageEngine\console,sid(...) session named
in the server error. Mapped the full native sequence:

  HistoryService.OpenConnection (have) -> StorageService.OpenStorageConnection
  (MISSING) -> StorageService.RegisterTags -> AddNonStreamValuesBegin (works) ->
  AddNonStreamValues(btInput) (fails - no console session) -> End(commit).

Two hard parts remain, each a live-production decode loop with no static shortcut:
(1) reproduce the 12-arg OpenStorageConnection handshake (several args inferred);
(2) decode the AddNonStreamValues btInput (C++-built, absent from decompiles; only
the 44-byte packed HISTORIAN_VALUE2 is known). Documented in revision-write-path.md.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01B6mcaT2PjRFKcogzp9UkfC

docs/plans/revision-write-path.md

@@ -81,14 +81,42 @@ gRPC *server* now holds the pipe, not the client). Because the error is identica
 framing, the blocker is **not** the `btInput` layout — it is a **missing storage-engine console
 session / tag-registration precondition** for the connection.
 
-**Next step to finish M3 (untested):** establish the StorageService side **before**
-`AddNonStreamValues` — `StorageService.OpenStorageConnection`/`OpenStorageConnection2` to open the
-console session, then register the tag→storage mapping (`RegisterTags` / `AddTagidPairs` /
-`AddShardTagids`), then retry `AddNonStreamValues` and finally `End(bCommit=true)` + SQL read-back on
-a sandbox tag. Each of those StorageService ops has its own buffer format to RE. Raw decode artifact:
-`artifacts/reverse-engineering/grpc-nonstream-decode/batch1-decode.txt` (gitignored). Probe command:
-`grpc-nonstream-decode`; driver: `HistorianGrpcRevisionProbe.ProbeNonStreamedBuffersAsync` (candidate
-guess-bytes live in the RE tool, not `src/`).
+**Required call sequence (mapped from the 2023 R2 decompile, corroborates the error above):** the
+missing precondition is **`StorageService.OpenStorageConnection`** — it creates exactly the
+`\\.\pipe\aahStorageEngine\console,sid(...)` console session named in the failure. The native
+non-streamed write path is:
+
+```
+HistoryService.OpenConnection            (✅ have it — the Open2 handshake)
+  → StorageService.OpenStorageConnection (⛔ MISSING — opens the console sid session; SEPARATE
+                                            storage session, returns its own uint handle + new GUID)
+  → StorageService.RegisterTags          (register the tag→storage mapping for the session)
+  → TransactionService.AddNonStreamValuesBegin   (✅ works)
+  → TransactionService.AddNonStreamValues(btInput) (⛔ currently fails here — no console session yet)
+  → TransactionService.AddNonStreamValuesEnd(bCommit=true)
+  → StorageService.CloseStorageConnection / HistoryService.CloseConnection
+```
+
+`OpenStorageConnection` (gRPC `StorageService`) takes 12 args — HostName, EnginePath
+(`\\.\pipe\aahStorageEngine\console`), FreeDiskSpace, ProcessName, ProcessId, UserName, Password(+len),
+ClientType, ClientVersion, ConnectionMode, ConnectionTimeout, StorageSessionId(in/out) — and returns a
+**new** storage `Handle` (uint) + a **new** StorageSessionId GUID (distinct from the Open2 GUID).
+
+**Two hard parts remain, each a separate live-production decode loop (no static shortcut):**
+1. **Reproduce the `OpenStorageConnection` handshake** — several of the 12 args are only inferable from
+   the decompile (ProcessId, ClientType/Version, ConnectionMode, the password-bytes framing), so the
+   exact values must be confirmed against the live server.
+2. **Decode the `AddNonStreamValues` `btInput`** — built in C++ (`SendNonStreamedValues` vtable call),
+   **absent from every decompile**; only the 44-byte packed `HISTORIAN_VALUE2` struct is known. Must be
+   decoded empirically once the console session exists (the batch-1 identical-error result could not
+   distinguish framings precisely *because* there was no session — with a session, framings should
+   diverge and the correct one becomes findable).
+
+Raw decode artifact: `artifacts/reverse-engineering/grpc-nonstream-decode/batch1-decode.txt`
+(gitignored). Probe command: `grpc-nonstream-decode`; driver:
+`HistorianGrpcRevisionProbe.ProbeNonStreamedBuffersAsync` (candidate guess-bytes live in the RE tool,
+not `src/`). **Status: M3 transaction lifecycle proven; full insert blocked on the
+OpenStorageConnection handshake + btInput decode — a focused follow-up, each step a live probe.**
 
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