Bug: V2 Node process-lock implementation imports unavailable node:ffi, blocking embedded SDK

Description

The V2 core's Node-conditioned process-lock module imports dlopen and getInt32 from node:ffi. On Node v26.8.1 this fails immediately with:

ERR_UNKNOWN_BUILTIN_MODULE: No such built-in module: node:ffi

We encountered this while embedding @opencode-ai/sdk@0.0.0-beta-18684 in an Electron/Node backend. After bundling past the separate extensionless-ESM problem tracked in #44582, this is the next runtime blocker. This report concerns POSIX process locking, not PTY support.

Versions / environment

• macOS 26.2, ARM64; Node v26.8.1.
• The offending import is present in core beta-18684 and beta-19086 (the current npm beta when checked).
• The isolated reproduction below was run against beta-19086. This is not a claim that the full latest SDK was otherwise validated.
• No plugins required.

Steps to reproduce

In an empty temporary directory, without installing dependencies or running lifecycle scripts:

npm pack @opencode-ai/core@0.0.0-beta-19086 --silent
tar -xzf opencode-ai-core-0.0.0-beta-19086.tgz
node --input-type=module -e 'await import("./package/dist/util/process-lock-ffi.node.js")'

The import fails with the error above, before any lock function is called. This direct file import is only a minimal reproducer, not a proposed SDK integration surface.

Expected behavior

The Node implementation should load and provide real interprocess locking on supported Node/Electron versions. If it requires a particular experimental runtime or flag, please document and validate that requirement. Disabling locking would not be a safe workaround.

The current V2 Node implementation and conditional import mapping still contain this path. A packed-artifact Node load test plus competing-process lock/release tests would help guard it.