daemon-relocation-spike

A throwaway probe that answers one empirical question for Phase 1 of the Windows update-survival work:

What is the minimal set of files that must be copied out of a packaged win-unpacked build so that a copied Orca.exe — run with ELECTRON_RUN_AS_NODE=1 from a directory outside the install dir — can: (a) start the terminal daemon and signal ready over IPC, (b) spawn a real ConPTY node-pty session, write input, and read output back, (c) do all of that while holding no open file handles into the app/install dir, so an NSIS update could delete the original install.

Why this matters

The daemon is fork()ed from the app's own Electron binary (Orca.exe) with ELECTRON_RUN_AS_NODE=1, from the install directory. On a Windows update, electron-builder's NSIS installer (a) runs uninstallOldVersion (deletes the registered install's files) and (b) CHECK_APP_RUNNING force-closes every process whose image path is under $INSTDIR. So the daemon dies and its held file locks can break the update.

The Phase 1 fix copies the daemon's whole file closure out of the install dir (into %LOCALAPPDATA%/userData) and forks the daemon from the copy, so its image + all loaded modules live outside $INSTDIR. This spike measures how small that copy can be while still working.

We keep the Electron binary run as node (not a stock node.exe): a prior attempt (#7473, reverted) switched to stock node and caused Windows-console flashing (stock node lacks Electron's kHideConsoleWindows) plus asar breakage. This spike does not reintroduce stock node.

Usage

# Real run (Windows, needs a packaged win-unpacked build):
node tools/daemon-relocation-spike/spike.mjs \
  --app-dir <path-to-win-unpacked> \
  --work-dir <scratch-dir> \
  [--tier full|no-gpu|minimal] \
  [--keep-work-dir]

# Offline logic validation (any OS, no build, no launch):
node tools/daemon-relocation-spike/spike.mjs --selftest

Exit code is 0 only when the run PASSES: daemon ready, PTY echo round-trips the nonce, the daemon's main module is the copied Orca.exe, and no loaded module resolves under --app-dir.

Tiers (defined as data in tier-file-set.mjs)

Every tier includes the irreducible core: Orca.exe, icudtl.dat, both V8 snapshot blobs (snapshot_blob.bin, v8_context_snapshot.bin), the daemon bundle (out/main/daemon-entry.js + chunks/ + out/package.json), and the whole node-pty package (native conpty.node + the sibling conpty/ runtime dir holding conpty.dll + OpenConsole.exe).

Tiers differ only in which top-level *.dll files they carry:

Tier	Top-level DLLs
full	all top-level *.dll
no-gpu	all except GPU/render DLLs (libEGL, libGLESv2, vk_swiftshader, vulkan-1, d3dcompiler_47); keeps ffmpeg.dll
minimal	none (exe + data blobs + daemon bundle + node-pty only)

Trimming further is a config change (edit TIER_DEFINITIONS / GPU_DLLS), not a code change.

How node-pty's native + ConPTY runtime is handled

The whole node-pty package tree is copied, and the entire win-unpacked layout is mirrored verbatim (every copy destination is relative to the win-unpacked root, not the asar-unpacked root). This matters because node-pty is packaged at resources/node_modules/node-pty — a sibling of app.asar.unpacked, not under it (see config/packaged-runtime-node-modules.cjs). Mirroring the full layout preserves two resolutions from the relocated path:

1. The daemon require-closure resolves require('node-pty') by walking parent dirs up from the mirrored resources/app.asar.unpacked/out/main/daemon-entry.js, which passes through resources/ and finds resources/node_modules/node-pty — exactly as in the packaged app.
2. node-pty's own native loader resolves conpty.node from build/Release (or prebuilds/win32-<arch>) relative to node-pty's own __dirname, and node-pty's Windows addon loads conpty.dll from <dir-of-conpty.node>/conpty/ and spawns OpenConsole.exe from beside it. Copying the tree verbatim keeps all three side-by-side.

ORCA_NODE_PTY_NATIVE_DIR

The reverted #7421 added a node-pty patch that reads ORCA_NODE_PTY_NATIVE_DIR to override the native dir. The current branch's config/patches/node-pty@1.1.0.patch does NOT contain that override — it was reverted. The spike therefore relies on layout preservation (copying the node-pty tree at its default relative path) rather than the env override. The spike still sets ORCA_NODE_PTY_NATIVE_DIR to the relocated native dir so it keeps working if pointed at a build that carries the patch, but on this branch the var is inert.

Implication for the real Phase 1 implementation: if the production copy does NOT preserve node-pty at the path its loader resolves by default (e.g. if the daemon-entry is relocated without the sibling node_modules/node-pty), the impl will need to re-add the ORCA_NODE_PTY_NATIVE_DIR patch from #7421. If it mirrors the layout as this spike does, the patch is not strictly required — though re-adding it is the more robust choice.

The handshake / client

ndjson-client.mjs is a small standalone NDJSON client (no electron/src imports) that mirrors src/main/daemon/daemon-server.ts:

1. Read the token the server writes to the token file after it begins listening.
2. Open a control socket, send hello {role:'control'}, await {type:'hello', ok:true}.
3. Open a stream socket with the same clientId, send hello {role:'stream'}.
4. createOrAttach on control, then write echo SPIKE-OK-<nonce>\r\n, and read data events on the stream socket until the nonce appears alone at line start (executed output, distinct from the echoed input line).

PROTOCOL_VERSION is read at runtime from src/main/daemon/types.ts so the client never drifts from the daemon.

The handle probe

loaded-modules.ps1 (via loaded-module-probe.mjs) runs Get-Process -Id <pid> and enumerates .Modules[].FileName. Any module path under --app-dir is a lock risk (the installer cannot replace a file a live process maps), so a passing relocation must show zero. It also asserts the process's main module is the copied Orca.exe, not the install-dir one.

Loaded DLLs are the lock-critical set. Data files (icudtl.dat, asar) are not memory-mapped as modules, so this probe does not enumerate them — the copy plan handles those by construction (they are copied, so nothing opens the originals).

What remains unverified until CI runs it

This session has no build, so the launch path is unproven. Verified here: node --check on every .mjs, a green --selftest, and clean pnpm exec oxlint. Open questions the real CI run must answer:

• Whether TIER_MINIMAL (no top-level DLLs) boots Orca.exe as node at all, or whether run-as-node still needs ffmpeg.dll / others — this is the core empirical result.
• Whether the daemon bundle require-closure needs any other unpacked node_modules beyond node-pty (surfaces as a ready-timeout if so).
• Whether any loaded module still resolves under --app-dir (the handle probe will name it).

Recommendation for the likely-minimal tier

no-gpu is the safe minimal target to ship: run-as-node Electron does not initialize the GPU/render stack, so libEGL / libGLESv2 / vk_swiftshader / vulkan-1 / d3dcompiler_47 are very unlikely to load, while ffmpeg.dll and the ICU/snapshot data are retained because the Electron bootstrap references them regardless of run-as-node. Run --tier minimal on CI first: if it PASSES, ship minimal; if Orca.exe fails to boot without the non-GPU DLLs, fall back to no-gpu. full is the always-works upper bound for comparison.