Pin ruff at 0.16.4 to match what the VS Code extension bundles

[lchoquel]

Part of the workspace-wide ruff 0.16.4 rollout (wip/updates/ruff-0.16.4-workspace-rollout-20260814.md). This is repo 2 of the scoped batch of seven, after cocode#83.

Why

Ruff 0.16 lints pyproject.toml itself, and the Ruff VS Code extension syncs config files to the language server. A pre-0.16 binary parses those TOML documents as Python source and paints phantom Ruff(invalid-syntax) diagnostics on lines like requires-python — read as requires - python, an invalid assignment target. The extension runs whatever binary it finds, repo venv first, so the venv pin is what has to move.

This repo is worth doing early despite its size: it is the starter template new projects are cloned from, so the stale pin was propagating into fresh checkouts rather than staying put.

The installed extension (charliermarsh.ruff-2026.74.0) bundles ruff 0.16.4, hence that version. Keeping the pin exact rather than a floor is what stops the editor and the CLI from drifting apart again.

What changed

• pyproject.toml: ruff==0.14.13 → ruff==0.16.4, plus the matching uv.lock update. This was the repo's only ruff pin site.
• wip/mode-split-clis.md: one Python code block reformatted. This is new 0.16 formatter behaviour — Ruff now formats Python embedded in Markdown — and merge-check-ruff-format in CI would fail without it. The change is blank lines around a nested function definition in a doc sample; no prose and no shipped code is touched.
• .vscode/settings.json: dropped "ruff.configuration": "--config=pyproject.toml". That setting takes a path to a config file, not a CLI flag, so the value never resolved — it only ever worked by falling back to Ruff's normal filesystem discovery, which finds the same pyproject.toml anyway.

Fallout: none in shipped code

Nothing shipped changes — ruff is a dev dependency. The upgrade produced zero lint findings, as the rollout plan predicted for this repo: the ruff config uses a narrow select list without preview, so none of the new preview rules or the noqa → ruff: ignore[...] migration that dominated the pipelex sweep applies. The generated piper/generated tree is already excluded from ruff, so the codegen.lock drift check is unaffected.

Verification

make agent-check (fix-unused-imports, ruff + plxt format and lint, pyright, mypy) and make agent-test both pass.

🤖 Generated with Claude Code

[greptile-apps]

Confidence Score: 5/5

The PR appears safe to merge, with no actionable changed-code defects identified.

The Ruff pin and lockfile agree, supported development platforms have matching artifacts, existing Ruff commands remain compatible, and removing the invalid editor setting preserves normal root configuration discovery.

_{Reviews (1): Last reviewed commit: "Pin ruff at 0.16.4 to match what the VS ..." | Re-trigger Greptile}