Agents kept re-checking the same v4 signatures (renames from Effect 3,
Schedule, CLI flags, MCP, vitest, vscode-jsonrpc failure modes). Record
them once and point to the file from CLAUDE.md.
The process is supervised: on exit after a successful initialize it is
spawned again with exponential backoff (500ms to 30s), open documents are
re-sent as didOpen before the new session is announced, and requests caught
by the crash wait for it and retry. A crash more than a minute after the
previous one starts a fresh streak; reaching the streak limit (default 3)
ends restarting for good, after which every request fails with an LspError
saying so. Restarts and give-ups are logged and forwarded to the MCP client.
Writes to the child's stdin go through a PassThrough so a broken pipe ends
the session instead of surfacing as an unhandled rejection.
Effect 4 MCP server (stdio/HTTP) bridging one LSP process: on-demand document
sync with LRU and disk change detection, push/pull diagnostics reconciliation,
capability-gated tools, diagnostics resources, tests against a fixture server.
EFLKumo