agentic-runtime-safety

Development

MANDATORY before editing runtime Lua under lua/agentic, except pure tests or docs. Covers multi-tab safety, public API session resolution, scoped Neovim state, buffer/window/keymap isolation, and scheduled callback rules.

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Agentic Runtime Safety

Every runtime feature must be multi-tab safe.

Architecture

SessionRegistry maps tab_page_id -> SessionManager.
AgentInstance owns one shared ACP provider subprocess per provider.
Each tabpage owns one ACP session ID, SessionManager, ChatWidget, status animation, permission manager, file list, and code selection.
Per-tab runtime data belongs on tab-scoped instances or Neovim scoped storage, never module-level mutable variables.

Public API chain

lua/agentic/init.lua is the public surface. Anything reached through this chain inherits its safety guarantees.

SessionRegistry.get_session_for_tab_page(nil, function(session)
    session.widget:show()
end)

Inside the callback:

Tabpage and session are resolved against the requested tab.
Callback is wrapped in pcall; errors are notified, not raised.

Outside the callback:

Bare-return calls can return nil when no ACP provider is configured.
After vim.schedule, re-enter via the callback form with self.tab_page_id or validate nvim_tabpage_is_valid(self.tab_page_id).
Never use the nil form after a schedule boundary when the original tab matters; nil resolves to the then-current tab.

Scoped storage

Use the narrowest valid scope.

Scope	Accessor	Purpose
Buffer	`vim.b[bufnr]`	Custom variables
Buffer	`vim.bo[bufnr]`	Built-in options
Window	`vim.w[winid]`	Custom variables
Window	`vim.wo[winid]`	Built-in options
Tabpage	`vim.t[tabpage]`	Custom variables

vim.b, vim.w, and vim.t are custom variables.
vim.bo and vim.wo are built-in options.
Invalid option names in vim.bo or vim.wo throw.
Write window-local options through vim.wo[winid][0].opt = value so they stay local to the window/buffer pair.

Isolation rules

Module-level constants are fine.
Module-level namespace IDs are fine: namespaces are global, extmarks are buffer-scoped.
Module-level mutable per-tab runtime state is forbidden.
Highlight groups are global and defined in lua/agentic/theme.lua.
Buffers and windows are tabpage-specific; use vim.api.nvim_tabpage_* APIs when looking up or validating UI state.
For window lookups, use vim.api.nvim_tabpage_list_wins(self.tab_page_id).
Prefer buffer-local autocommands.
Filter global autocommands by tabpage.
Use BufHelpers.keymap_set and BufHelpers.keymap_del for buffer-local keymaps. Do not call vim.keymap.set or vim.keymap.del directly with buffer options.

Cleanup path

flowchart LR
    A[TabClosed autocmd] --> B["SessionRegistry.destroy_session(tab_page_id)"]
    B --> C["SessionManager:destroy"]

Public entries

Widget lifecycle: open, close, toggle, rotate layout.
Context attach: selection, files, diagnostics.
Session operations: new, restore, stop.
Provider switch: UI history replay only; the new provider receives no prior LLM context.
Config entry: setup.