[audit] Neovim 0.12.5 changed :restart's default behavior to save/restore session — interacts with server.lua's hop workflow

[stanfish06]

What

Neovim 0.12.5 (tagged 2026-08-23, one day before this audit cycle) backported a breaking change to the built-in :restart command: :restart with no bang now saves and restores the session (buffers + window layout) by default; the old "just restart, don't preserve anything" behavior moved to :restart!. ZR was also newly mapped as a shortcut for restart.

• feat(:restart)!: no bang restores session and window layout (feat(:restart)!: no bang restores session and window layout neovim/neovim#40321, merged 2026-06-29)
• feat(editor)!: ZR restores session (feat(editor)!: ZR restores session neovim/neovim#40498, merged 2026-07-09)
• backported to the release-0.12 branch (backport: feat(restart)!: ZR restores session neovim/neovim#40669, merged 2026-07-10), first shipping in the v0.12.5 patch tag

Both are marked as breaking (!) commits, even though delivered inside a patch release rather than a minor version bump.

Where

lua/config/server.lua:196-198 — the comment on ui_is_cross_machine() explicitly documents this config's own understanding of Neovim's built-in :connect/:restart server/client commands as part of its custom remote-hop tooling (":connect/:restart only work when the UI and server share a machine, so re-hopping is blocked from remote sessions").

Why it matters

server.lua builds a whole custom nvim-server-hopping feature (:NvimHop, :NvimRemote, :ShowNvimServers) on top of Neovim's native client/server primitives, and its own comments show the author already tracks :restart's semantics closely enough to gate re-hopping behavior around it. The config doesn't currently call :restart programmatically (grep confirms no vim.cmd.restart or scripted :restart invocation), so nothing breaks automatically — but a user typing :restart or the new ZR on a 0.12.5+ host now gets session-restore-by-default instead of a clean restart, which could resurrect buffers/window layout in the middle of a remote-hop session in a way this module wasn't written to anticipate.

Recommended action

• No code changes are strictly required today.
• If :restart/ZR is used manually as part of the hop workflow, be aware the plain form now restores session state; use :restart! for the previously-expected "clean" behavior.
• Worth a short note near the ui_is_cross_machine() comment (or :ShowNvimServers help text) flagging the new default, since this module already documents :restart interactions for readers.
• Not related to nvim-treesitter or completion breaking changes already tracked in [audit] Neovim 0.12 breaking changes — plugin compatibility checklist #283 — this is a distinct 0.12.5 patch-release change, not part of the 0.12.0 changelog that issue covers.