Tests(chore): Run the mcp adapter suite in the gate

why: fastmcp is only the optional `mcp` extra, so a plain `uv sync`
prunes it -- which silently turns `uv run mypy` red and makes every
fastmcp adapter test importorskip away. The committed adapter's green
gate depended on fastmcp happening to be installed.

what:
- Add fastmcp + tomlkit to the dev and testing dependency-groups so the
  standard gate type-checks and runs the adapter + mcp_swap tests
  (fastmcp also stays the `mcp` extra for end users)
- Add --ignore=docs/_build to pytest addopts: `docs` is a testpath, so a
  stale built-HTML tree poisons collection (the gate's rm docs/_build
  first-step was the only guard)
- Reformat ops/plan.py (pre-existing blank-line drift surfaced by ruff)
- uv.lock: add tomlkit (no other version churn)

Author: tony

pyproject.toml

@@ -65,6 +65,12 @@ dev = [
   "pytest-mock",
   "pytest-watcher",
   "pytest-xdist",
+  # MCP adapter — the optional `mcp` extra, included here so the gate
+  # type-checks (mypy) and exercises the fastmcp adapter + its tests
+  # instead of silently skipping them.
+  "fastmcp",
+  # Scripts (scripts/mcp_swap.py dev tool)
+  "tomlkit",
   # Coverage
   "codecov",
   "coverage",
@@ -88,6 +94,10 @@ testing = [
   "pytest-rerunfailures",
   "pytest-mock",
   "pytest-watcher",
+  # MCP adapter (optional `mcp` extra) so the adapter tests run here too
+  "fastmcp",
+  # Scripts (scripts/mcp_swap.py dev tool)
+  "tomlkit",
 ]
 coverage =[
   "codecov",
@@ -315,7 +325,10 @@ addopts = [
   "--showlocals",
   "--doctest-docutils-modules",
   "-p no:doctest",
-  "--reruns=2"
+  "--reruns=2",
+  # Built HTML lives under docs/_build and `docs` is a testpath; never
+  # collect generated artifacts (their relative directives fail to parse).
+  "--ignore=docs/_build",
 ]
 doctest_optionflags = [
   "ELLIPSIS",

src/libtmux/experimental/ops/plan.py

@@ -238,6 +238,7 @@ def preview(self, *, version: str | None = None) -> list[tuple[str, ...] | None]
         >>> plan.preview()
         [('split-window', '-t', '@1', '-v', '-P', '-F', '#{pane_id}'), None]
         """
+
         def _render(op: Operation[t.Any]) -> tuple[str, ...] | None:
             try:
                 return op.render(version=version)