# M1 spikes (docs/WINDOWS_PORT.md §13) Programs that answer questions the port is currently *guessing* at. They are checked in and runnable on purpose: a spike whose answer nobody can reproduce six months later is a rumour. They are deliberately **not** in `windows/Nucleic.sln`. The solution's broker contract tests must keep running on any machine against `FakeWslc`; these need the `Microsoft.WSL.Containers` preview NuGet and a real WSL stack, so they are built by path. --- ## `WslcApiDump` — what does the wslc API actually look like? **Status: it has served its original purpose (docs/WINDOWS_PORT.md §13.1).** The real API is known, and it was obtained without a Windows machine at all — the package is public, so the `.nupkg` was downloaded, its projection assembly extracted, and its metadata read with `MetadataLoadContext`. What this tool is *for* has therefore changed: its assumption list now describes the surface actually observed in 2.9.3, so running it says **what the next package version moved**, not what we guessed wrong. **Why it is still reflection.** Same reason as before: a typed check fails to compile on the first rename and reports one problem, where this reports all of them at once. That property is worth keeping for a preview API whose next version can break anything. Two facts it discovered that anything referencing this package needs: - the assembly is **`wslcsdkcs.dll`**, not `Microsoft.WSL.Containers.dll` — loading it by package name fails; - the only published version is **2.9.3**, targeting `net8.0-windows10.0.19041.0`. The `0.1.0-preview.1` pin this repo carried could never have restored. ```powershell cd windows/spikes/WslcApiDump dotnet run # dump the API + check every facade assumption dotnet run -- --probe # + GetMissingComponents / GetVersion dotnet run -- --session # + create a session, a SECOND with the same name, identity-test, tear down dotnet run -- --session --keep # …and leave the sessions running afterwards dotnet run -- --all-types # include the ABI/marshalling plumbing in the dump dotnet run -- --internal # can the SERVICE-INTERNAL COM interface be reached? (QI only) dotnet run -- --internal-call # …and call through it (can crash — that is the finding) ``` **If it reports missing components**, the machine cannot run wslc yet, and the two components are NOT fixed the same way — the tool prints the specific remedy for each: | Missing | Fix | | --- | --- | | `VirtualMachinePlatform` | `wsl --install`, then **reboot** (an OS optional feature). | | `WslPackage` | `wsl --update --pre-release`, then `wsl --shutdown`. WSL is installed but older than the SDK, and **2.9.3 is pre-release-only — a plain `wsl --update` will not get there.** Confirm with `wsl --version`. | | `SdkNeedsUpdate` | The NuGet pin is ahead of the installed service: update WSL further, or pin the package back. | The distinction is worth knowing because the failures look alike but mean opposite things: `REGDB_E_CLASSNOTREG` (0x80040154) is *nothing installed*, `ERROR_NOT_SUPPORTED` (0x80070032) is *installed but too old*. The tool decodes both, along with the `WSLC_E_*` range from `wslc.idl`, because these COM exceptions often carry an empty message and leave nothing but a hex code. `--session` is skipped while components are missing rather than failing the same way. Note that the assumption check reads the **`Microsoft.WSL.Containers`** namespace only. That is correctness, not tidiness: a C#/WinRT projection also exports `ABI.Microsoft.WSL.Containers.*` marshalling types with the *same short names*, and matching on short name alone checks every member against the marshalling struct — which reported 42 false MISSINGs, with `CreateMarshaler` helpfully offered as the nearest name. It writes the full public object model to `wslc-api-dump.txt` (`--out` to relocate) and prints an `ok` / `MISSING` line per assumption, each with *why that member matters* and a nearest-name hint. It exits 0 even when assumptions fail — a mismatch is the product, not an error. Only a genuinely broken run (the assembly won't load) exits non-zero. `--probe` has been **run clean on real hardware** (Windows 11 amd64, WSL 2.9.3): 54/54 `ok`, no missing components. Every other path is exercised against a stand-in assembly carrying the observed 2.9.3 shape — the `ABI.` shadow types, a service reporting missing components, an `0x80070032` with an empty message, a `ServiceVersion` with no `ToString()` override, and a duplicate-name `Session` throwing `0x80040607` — so a failure on your machine is a finding about wslc, not about this tool. Note the `ToString()` one, because it bit: a WinRT projection class does not override `ToString()`, so printing a returned object gives you its *type name*. Values are rendered by their properties instead — `ServiceVersion { Major=2, Minor=9, Revision=3 }`, not `Microsoft.WSL.Containers.ServiceVersion`. **What to send back:** the console output, and `wslc-api-dump.txt` if anything is MISSING — which now means the package moved under us, not that we guessed wrong. ### Why `--session` earns its risk `--session` creates a real wslc session named `nucleic-spike` under `%LOCALAPPDATA%\Nucleic\spike\wslc`, starts it, and then **creates a second one with the same name**. That second construction is the whole point, and it is the last open question D13 turns on: the compat SDK exposes a `Session` *constructor* and no attach, so does constructing over an existing name re-adopt it, or refuse? **Answered on 2.9.4: it cannot.** The constructor is lazy and always succeeds — judging by it is what made the first reading of this probe wrong. `Start()` is where the service is consulted, and a second `Start()` on a running name fails with `ERROR_ALREADY_EXISTS` (0x800700B7). Note it is *not* `WSLC_E_SESSION_RESERVED`, which exists in `wslc.idl` but evidently means something narrower — don't key on it. So the probe judges on `Start()`. If a future version lets the second `Start()` through, it then runs an **identity test**: terminate the FIRST session and read from the SECOND. A read that worked before and fails after is one underlying session answering both handles; a read that keeps working means two independent VMs. The identity test deliberately uses only the compat SDK. The obvious check would be `wslc session ls` — but **`wslc.exe` is not on PATH by default**, so a spike that depends on it answers nothing on a stock machine. (It ships beside `wsl.exe`; try `C:\Program Files\WSL\wslc.exe`. That it isn't on PATH is one more small argument for D13's no-CLI stance.) Sessions are **torn down at the end** by default — an earlier version left a WSL VM running and told you to clean it up with a command that doesn't exist. Pass `--keep` to leave them, which is how you check the other half of the §2.3 question: whether session state outlives the process that created it. With `--keep`, `wsl --shutdown` clears everything. The gateway address is *not* what this probe is for — §13.1 established that no API surfaces one, so it comes from `GetAdaptersAddresses` over `vEthernet (WSL)` instead, which `WslcFacade` now does. ### `--internal` — is D13's internal arm even reachable? The newest open question, and the one item 5 stopped at (docs/WINDOWS_PORT.md §13.2). D13 routes enumeration, reattach and the Terminal panel's pty to the service-internal `IWSLCSessionManager` (IID `82A7ABC8-…`). But **`wslc.idl` declares interfaces and no activatable class** — there is no CLSID in it, so `CoCreateInstance` has nothing to name. The only registered coclasses in WSL's IDLs belong to the compat surface (`WSLCCompatSessionManager` and its factory) and to the WSL service proper (`LxssUserSession`, `LxssUserSessionInBox`). **Answered on hardware (WSL 2.9.4): yes.** `WSLCCompatSessionManager` (`a9b7a1b9-0671-405c-95f1-e0612cb4ce8f`) — the same class the SDK itself activates — answers a QI for `IWSLCSessionManager`. One object, two faces. `IWSLCVirtualMachine` was refused by every class, confirming §13.1's retraction against the machine rather than against an IDL. `--internal-call` then confirmed the **vtable** matches the IDL: `GetVersion()` (slot 3) returned 2.9.4, agreeing with the compat `WslcService.GetVersion()` in the same run — the same service answering through both faces — and `ListSessions()` (slot 6) returned S_OK. So hand-written `ComImport` is sufficient and the C++/WinRT shim §13.1 mused about is not needed. Re-run as `--session --keep --internal-call`, `ListSessions` returned the live session by name (`#6 "nucleic-spike"`), so the entry-struct layout — inline `wchar_t` buffers, the same shape `ListContainers` uses — marshals as declared. **Enumeration is proven.** That run also turned up a trap worth knowing before writing any of this into brokerd: `OpenSessionByName` failed **`0x80070542`** on the session `ListSessions` had just listed. That is `ERROR_BAD_IMPERSONATION_LEVEL` — the service impersonates the caller to resolve a *per-user* session, and .NET hands COM proxies `RPC_C_IMP_LEVEL_IDENTIFY` by default. A security error that reads exactly like "not found", and only on the methods reattach needs. The probe now raises the proxy blanket to `RPC_C_IMP_LEVEL_IMPERSONATE`; brokerd should call `CoInitializeSecurity` at startup instead, **before** its first COM call — including the compat SDK's, or it fails `RPC_E_TOO_LATE`. `wsl --shutdown` to clean up after `--keep`. The hypothesis was that one of those objects also implements the internal interface — COM objects routinely expose several — so `--internal` activates each and QIs for the internal IIDs. It **never calls a method**, so a vtable mismatch cannot crash it, and QI alone answers the question. `--internal-call` then calls `GetVersion` (slot 3) and `ListSessions` to confirm the vtable really matches the IDL; *that* can take the process down, which is why it is opt-in. It also QIs `IWSLCVirtualMachine`, which is **expected to fail**: per the IDL only `IWSLCVirtualMachineFactory::CreateVirtualMachine` produces one, and the SYSTEM service owns the factory. §13.1's hvsocket-primary decision was retracted on that reading, and a decision reversed by reading deserves confirming against the machine. ### The answers that change the design Most mismatches are a one-line edit in `WslcFacade.cs` — that is exactly what the `IWslc` seam is for, and nothing above it should move. These three are different: | Finding | Consequence | | --- | --- | | No container enumeration, stats, pty or attach in the SDK | **D13's answer, now gated.** They exist on `wslc.idl`, the service-internal interface `wslc.exe` calls — but that IDL declares no coclass, so reaching it at all is what `--internal` tests. Stats no longer wait on it: `WslcFacade` reads cgroup v2 in the guest instead. | | `Container` has no `Name`, `Session` has no `GetContainers()` | Sharper than "no enumeration": a container is reachable ONLY through the handle `CreateContainer` returned, so the broker keeps its own name→handle roster — which dies with the process. A restarted broker sees an empty sandbox (§13.2). | | No create-or-attach on `Session` | `IWSLCSessionManager::OpenSessionByName` / `EnterSession` — same gate as above. Until then `session.ensure` fails `session_exists` and names `wsl --shutdown` as the remedy. | | No gateway address anywhere on the API | **Gateway TCP stays primary.** The hvsocket alternative needed a VMID from `IWSLCVirtualMachine::GetId`, and that interface is unreachable from a client — retracted in §13.1. The address comes from `GetAdaptersAddresses` over `vEthernet (WSL)`. | | No uid on `ProcessSettings` | Recoverable, and already planned for: exec wraps argv in `setpriv`/`su agent -c`. Interceptors and nash don't care about the numeric uid (§3.2). | --- ## Not yet written - **`WslcSpike`** — the typed happy path: session → GHCR pull of `naros-agent` → container with an NTFS `ContainerVolume` → `exec git status` in the bind-mounted worktree → stdio round-trip → SIGTERM, plus the 9P latency numbers §15 wants (`git status` and `npm install` on a real repo, mounted vs. in-VM). Deliberately held back until `WslcApiDump` has run: written now, against guessed names, it would not compile, and fixing it blind is the mistake this whole approach exists to avoid. - **`GatewaySpike`** — M1 (b), and the control-plane spike that actually matters now: can a `Bridged` wslc container reach the host at the `vEthernet (WSL)` address `WslcFacade` returns, under the **default** Windows firewall, and does `control-bridge.js` complete an MCP round trip over it? This is the committed path, not a fallback. - **`HvSocketSpike`** — downgraded back to upside (§13.2). It needs a VM GUID to bind `AF_HYPERV` to, and `IWSLCVirtualMachine::GetId` turned out to be unreachable from a client, so the VMID would have to come from outside wslc entirely — HCS enumeration, or the WSL VM's registry identity. Worth doing only if the gateway path shows friction in the wild; not on the M2 path.