Problem:
TM_DIRECTORY expands to the directory's basename, losing its parent path.

Solution:
Remove the tail modifier when expanding the current file's directory.
Extend the existing known-variable test to check the full directory path.

AI-assisted

Enable EmmyLua's assign-type-mismatch diagnostic after correcting the
runtime annotations and assignments it flags.

Correct option, tuple, and return types, and use separate locals when a
value changes representation. Add guards and narrow casts where needed
so the runtime passes the stricter check. Regenerate the affected docs.

AI-assisted

Enable EmmyLua's need-check-nil diagnostic and resolve nullable values
through more precise types, explicit invariants, and guards for missing
runtime state. Keep analyzer-specific workarounds local and update the
affected API documentation.

Exclude the bundled re.lua from analysis so its nil-check warnings do
not fail CI.

AI-assisted

Problem:
If a snippet does not have a placeholder, we use insert mode instead of
select mode. From here <Esc> leaves the session and highlight active.

Solution:
Cancel the session on <Esc>.

Problem:
`nvim_create_autocmd` is too verbose and its `callback` requires extra
"nesting".

Solution:
Introduce `nvim_on`. Start using it internally. Then we can get a feel
for how it should look before making it public.

Problem: <Esc> in a Select-mode tabstop leaves the session and highlight active.
CursorMoved isn’t triggered since the cursor doesn’t move.

Solution: use ModeChanged (s:n) instead. Defer with vim.schedule() to avoid transient
s:n from jump().

Allow `bufnr` as a positional param name because it is very common.
However as a field name, or part of a function name, it is usually
a mistake.