orca/docs/reference/windows-process-enumeration.md

Reading the Windows process table

Orca needs three things from the Windows process table: who a PID's parent is (descendant walks and teardown identity), what a process is running (agent recognition), and how much memory/CPU it uses (Resource Manager).

Node cannot answer the first one without native code. That is why seven independent readers existed, each forking powershell.exe to run Get-CimInstance Win32_Process, with a wmic fallback that Windows 11 24H2 has since removed.

Use the native snapshot

src/main/windows/windows-process-table.ts is the only module that may read the table. It wraps a Toolhelp32 snapshot from @vscode/windows-process-tree.

import { readWindowsProcessTable, readWindowsProcessTableFresh } from '../windows/windows-process-table'

• readWindowsProcessTable() — shared TTL cache. Use for anything periodic.
• readWindowsProcessTableFresh() — a snapshot that starts after the call. Use for teardown identity, where a cached row can predate the exit it is being asked about.

Both reject when the table cannot be read. Do not convert that into an empty array. An empty table is a claim that nothing is running, and callers act on that claim by declaring a tree dead or a shell childless. "Unavailable" has to stay distinguishable from "empty" — collapsing the two is how a PTY tree survived its own teardown (#9045).

Measured on Windows 11 with 1050 processes (p50 / p95):

	p50	p95
pid + ppid + name	15.9 ms	17.5 ms
+ memory + command line	30.6 ms	33.7 ms
Get-CimInstance via PowerShell	706 ms	723 ms

Those CIM numbers are from a 1050-process host. The scan scales with process count: on a 1486-process Windows SSH host it measured 1.36 s and produced 4.8 MiB of JSON, against the fallback's 3 s and 8 MiB limits. Both limits match the pre-#15749 reader, so relay hosts are at parity rather than newly at risk — but the headroom is roughly 2x on time and 1.7x on bytes, not the ~4x the 706 ms figure implies. On overflow the output is truncated, the JSON fails to parse, and the read rejects, so a busy host loses the table rather than receiving a wrong one.

The relay has no binding, and falls back

Relay deployment installs only node-pty and @parcel/watcher on the remote host (RELAY_NATIVE_DEPS in src/main/ssh/ssh-relay-deploy.ts), so a Windows machine used as an SSH host has no @vscode/windows-process-tree at all. It is not added there on purpose. Both ways of installing it fail, and both were checked on a real Windows SSH host with 1486 processes:

Installing it normally rebuilds from source, and that build fails. The tarball carries a binding.gyp, so npm runs node-gyp rebuild regardless of what is already compiled inside it. On a host that already had MSVC Build Tools 2022 installed, that build still failed:

error MSB8040: Spectre-mitigated libraries are required for this project.

That is the requirement the binding.gyp hunk of our patch deletes, and the patch cannot reach a remote host — pnpm patches do not cross SSH. Relay deploy would then break outright rather than degrade: installNativeDeps throws on failure, and the toolchain-skip retry is gated to Linux.

Skipping the build and using the shipped binary returns a truncated table. Contrary to what this file used to claim, the published 0.8.0 tarball does contain build/Release/windows_process_tree.node — an MSVC build directory that looks accidentally published (.obj and .tlog files ship with it). It is N-API, so it loads on any modern Node. But it predates our patch and still has the process_count < 1024 cap, so on that 1486-process host:

LOADED OK
rows=1024
selfPid=21964 present=false

Exactly 1024 rows, with the querying process itself among the missing. The self-presence guard rejects that, so the fallback engages anyway — but only on hosts busy enough to cross the cap. That is worse than no binding at all: it works on a quiet machine and fails silently under load, which is precisely the shape of bug that survives testing.

So the constraint is not that no binary exists to ship. It is that the only binary available to ship is the broken one, and building the good one needs a toolchain the remote does not have.

Instead, windows-process-table.ts falls back to readWindowsProcessRowsWithCim (windows-process-table-cim-scan.ts), the Get-CimInstance scan this module replaced. The gate is deliberately narrow:

• it engages only when the module cannot be required, never when a loaded module fails, wedges, or returns an unreadable table — a present-but-failing reader must not silently start forking a shell at the caller's poll rate;
• a fallback that also fails still rejects, so "unavailable" never degrades into "nothing is running";
• the scan applies the same self-presence guard as the native path.

src/main/ssh/relay-native-dependency-coverage.test.ts asserts that every native addon reachable from the relay entry is either installed on relay hosts or listed there with the reason its absence is safe. That test exists because #15749 shipped this gap: the relay tests injected a fake module through __setWindowsProcessTreeLoaderForTests, so nothing exercised the real require.

The native fast path stays unavailable on relay hosts until we ship our own patched .node as a relay asset — the addon is N-API, so one binary per RELAY_BUILD_PLATFORMS Windows arch would load against whatever Node the remote runs, and config/relay-assets/ already carries a shipped-with-the-relay file for node-pty. That is a packaging change, not a code change, and it is a real gap tracked separately.

Why the package is patched

config/patches/@vscode__windows-process-tree@0.8.0.patch carries two hunks.

1. Spectre mitigation. The upstream binding.gyp requires Spectre-mitigated libraries, which Orca's Windows build agents do not install. node-pty is patched the same way for the same reason.
2. The 1024-process cap. GetRawProcessList stopped after 1024 entries. Measured on a real host with 1051 processes, the module returned exactly 1024 and the querying process was itself among the 27 missing. A truncated snapshot silently hides the descendants a teardown is trying to reap — the exact failure the native path exists to remove.

The typings claim commandLine is truncated at 512 characters. Measured, it is not: the longest observed on a real host was 26,059.

Packaging

The addon is Windows-only, so it follows the same contract as windows-native-registry (asserted by config/scripts/package-electron-runtime-contract.test.mjs):

• an optionalDependency, so a macOS/Linux install tolerates its absence;
• not in pnpm.onlyBuiltDependencies — pnpm installs optional dependencies on every host, and macOS/Linux must never run node-gyp for it;
• listed in the win32 branch of rebuild-native-deps.mjs and ensure-native-runtime.mjs;
• copied into the packaged node_modules for win32 only.

What the snapshot does not provide

CreationDate (process start time) has no equivalent. Anything using a start time to prove a PID has not been recycled — daemon identity, managed-hook ownership, and CPU accounting in the memory collector — still reads it through its own query. Those callers are not migrated.

Start time is a proxy for identity, not identity. The durable answer for the process trees Orca itself spawns is an inherited handle: a job object names the tree Orca created, so no start-time comparison is needed. Those readers should be resolved that way rather than by adding a start time to this module.

Do not adopt getProcessCpuUsage() from the package. It takes both CPU samples inside one call with a blocking Sleep(1000) in the middle, which would hold a libuv threadpool slot for a full second out of the Resource Manager's two-second poll.

Owning a PTY's process tree

src/main/windows/windows-pty-job.ts is the counterpart to reading the table: it answers "is this tree mine, and how do I kill it?" with a handle instead of an inference.

node-pty is patched (config/patches/node-pty@1.1.0.patch) to create a job object per ConPTY and assign the shell to it under CREATE_SUSPENDED, before the shell can spawn anything. Assigning after the fact leaves a window in which a fast child escapes the job.

• terminatePtyJob(proc) — one TerminateJobObject call for the whole tree.
• listPtyJobProcessIds(proc) — the live pids under a tree that is still tracked, including children that detached from the console.

Measured on Windows 11 against a shell whose grandchild was spawned detached: job membership was [shell, grandchild] and one call killed both. Neither a parent-pid walk nor GetConsoleProcessList sees that grandchild — it leaves the console and reparents, which is what left claude.exe/node.exe/cmd.exe holding worktree directories open (#9045, #10475, #10897).

The per-PTY job deliberately does not set JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE. Measured on Windows 11: with that flag, releasing the handle when the shell exits also kills whatever the user left running, so typing exit in a pane reaped a start /b server that used to survive. The job exists to make an explicit teardown exact, not to redefine what a clean exit means.

Reaping a dead daemon's shells (#9195, #10415) is therefore a second, nested job, not this one. The terminal daemon assigns itself to a kill-on-close job at startup (assignHostProcessToKillOnCloseJob); children inherit membership, so every pty is covered and the per-PTY jobs nest inside it. Its handle is released only when the daemon process dies, so a crashed daemon reaps its tree without changing what a clean shell exit means.

The split is the point. One job answers "kill exactly this pane's tree, now"; the other answers "do not strand anything if the host dies". Trying to get both from one job is what reaped users' backgrounded work on a clean exit.

It belongs to the daemon and never to the app: an app-main crash must still leave sessions alive, which .github/workflows/win-crash-survival-e2e.yml asserts. The app spawns the daemon detached and is itself in no job, so nothing is inherited across that boundary.

The consequence is that a PTY hosted by the app rather than the daemon gets a per-PTY job but no crash reaping. That is deliberate — the alternative is a kill-on-close job on the app, which is exactly what the crash-survival guarantee forbids.

Once the shell exits, node-pty drops its handle record and closes the job, so a terminated tree reports null rather than []. Null means unverifiable in the sense of ssh-execution-boundary.md — no job support, not a ConPTY, or no longer tracked. It is never evidence that processes died.

Both functions report unavailable / null rather than a false success when a pty has no job — an outer job without JOB_OBJECT_LIMIT_BREAKAWAY_OK (some EDR and container hosts) can refuse the assignment, and a pty started before this build has none. Callers must fall back, not conclude the tree is gone. That conflation is the original bug.

Known limitation: the baton table is not synchronised

node-pty keeps its per-terminal handles in a plain std::vector and erases from it on a detached exit thread, while get_pty_baton is called from the main JS thread. That race predates this change — PtyResize, PtyClear and PtyKill all read the table the same way — but terminatePtyJob adds an instance of it: the exit thread can close hJob between the lookup and TerminateJobObject.

Losing that race normally just returns FALSE, which surfaces as unavailable and falls back. The case that would not be benign is a recycled HANDLE value, where the call could reach a different job in the same process. Fixing it properly means synchronising node-pty's handle table rather than adding a lock around one accessor, so it is deliberately left alone here.

The patch must actually be compiled

node-pty prefers its upstream prebuild and only builds from source when npm_config_build_from_source is set or no prebuild exists for the platform. The Windows prebuild does not contain this patch, so a plain pnpm install on Windows yields a node-pty without the job-object exports — and terminatePtyJob then reports unavailable on every call, which is indistinguishable from a correctly degraded build.

Packaging is unaffected: rebuild-native-deps.mjs rebuilds node-pty from source for Electron and restores the ConPTY runtime files that a bare node-gyp rebuild skips. The gap is the node-runtime test environment, which is why the Windows CI job rebuilds from source before running the win32 suites.

isPtyJobOwnershipAvailable() exists for exactly this: the win32 suite asserts it is true before asserting anything else, so an unpatched binary fails loudly instead of passing every case vacuously. That guard is what caught this.

requiresPatchedNodePtySourceBuild() in ensure-native-runtime.mjs still exempts win32, on the premise that the patch is Unix-only. That premise is now false, but lifting the exemption also needs pnpm rebuild to force a source build — otherwise the assertion fires and the remedy does not fix it. Left as a follow-up rather than changed blind.