py(deps[dev]): ruff 0.16.0

[tony]

Summary

• Migrate dev tooling to ruff 0.16.0, pinning a floor so contributors and CI resolve the same linter release instead of whatever each machine happened to install.
• Adopt ruff's curated default rule set by switching select to extend-select, taking the project from 351 enabled rules to 565.
• Fix every finding the default set surfaced, and scope a per-file ignore — with its reason recorded in the config — around each idiom that is deliberate.

Changes

pyproject.toml — ruff moves from unpinned to >=0.16.0 in both the dev and lint dependency groups. [tool.ruff.lint] select becomes extend-select, with every entry on its own line and a trailing comment naming the linter it selects.

uv.lock — relocked, ruff 0.15.22 to 0.16.0.

AGENTS.md, docs/topics/plugins.md — ruff 0.16.0 formats Python code blocks in Markdown by default. The plugin authoring example picks up double quotes; the Colors example loses its hand-aligned trailing comments. Mechanical, no prose or semantics touched.

CHANGES — entries for the floor bump and for the default rule set adoption.

Design decisions

ruff 0.16 ships a 413-rule default set as its recommended baseline. An explicit [tool.ruff.lint] select replaces that set rather than extending it, so this project was running its own prefix list and silently opting out of everything else. No selector token names the default set, so leaving select unset and layering the project's linters on with extend-select is the only way to get defaults-plus-extras.

Expanding to whole prefixes instead was considered and rejected: it drags in all of D, PL, S, and friends rather than the curated subset, which is one to two orders of magnitude noisier for no corresponding signal.

Rules fixed

• PLE0101 return-in-init — the exception and validation-error classes returned the result of super().__init__(...), which the constructor protocol discards. Now called as a statement.
• PLW0127 self-assigning-variable — leftover p = p / session = session scaffolding in the classic builder, the workspace loader, and the builder, freezer, and helper tests. Removing them left one loop variable unused, renamed to _p so the iteration that creates the panes still runs.
• PYI034 non-self-return-type — PrivatePath.__new__ and Spinner.__enter__ were annotated with the concrete class, so a subclass of either got typed as the base. Both return Self, imported from typing_extensions under t.TYPE_CHECKING because the floor is Python 3.10.
• ISC004 implicit-string-concatenation-in-collection-literal — the <svg> open tag in the layout extension is now parenthesized, so a stray comma cannot silently split one list element into three.
• PLW1508 invalid-envvar-default — the COLUMNS and ROWS lookups passed int defaults, making os.getenv return str | int depending on whether the variable was set. String defaults throughout.
• PLW1510 subprocess-run-without-check — the help-example test asserts on returncode itself, so check=False is now explicit.
• T100 debugger — the pdb.set_trace fallback sat behind PY3 and PYMINOR >= 7, which cannot be false on Python 3.10. Dropped, along with its unreachable import pdb.
• YTT201 sys-version-info0-eq3 — PY3 compared the major version with ==, which would flip every consumer to the Python 2 path the day the major version increments. Now >=.
• TC004 runtime-import-in-type-checking-block — tests/test_util.py imported pathlib twice; the copy inside the type-checking block never bound anything.
• EXE001 shebang-not-executable — src/tmuxp/log.py carried a #!/usr/bin/env python line but is imported rather than run, has no __main__ block, and is tracked non-executable. Shebang removed. Note that ruff does not enforce this rule under WSL, so it surfaces only on a Linux runner.

Ignores added

Each is scoped to a single file and carries its reason in pyproject.toml.

• S102 exec-builtin in docs/conf.py — Sphinx reads the version metadata by exec-ing __about__.py into a dict, which keeps conf.py from importing the package it documents.
• S102 exec-builtin in src/tmuxp/cli/shell.py — tmuxp shell -c is documented as "execute python code in libtmux and exit". Running the operator's own code in a tmux-aware namespace is the command's purpose, not an injection sink.
• S102 exec-builtin in src/tmuxp/shell.py — the interactive console sources $PYTHONSTARTUP and ~/.pythonrc.py the same way CPython's own REPL does.
• BLE001 blind-except in src/tmuxp/log.py — a log formatter must never raise. record.getMessage() interpolates caller-supplied args, so whatever their __str__ throws has to be rendered into the line rather than propagating into the operation being logged.
• PLW0127 self-assigning-variable in src/tmuxp/_compat.py — breakpoint = breakpoint at module scope is not a no-op. The right-hand side resolves to the builtin and the assignment binds it as a module attribute, which is what makes from tmuxp._compat import breakpoint work in tmuxp.cli.shell; module attribute lookup has no builtins fallback.

Test plan

• uv run ruff check . — all checks passed
• uv run ruff format . --check — all files already formatted
• uv run mypy — no issues found
• uv run py.test — full suite green under tmux locally
• CI green across the tmux version matrix

[codecov]

Codecov Report

❌ Patch coverage is 80.00000% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.55%. Comparing base (96a1e73) to head (ff9334c).

Files with missing lines	Patch %	Lines
src/tmuxp/exc.py	72.72%	3 Missing ⚠️
src/tmuxp/cli/convert.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1081      +/-   ##
==========================================
- Coverage   82.56%   82.55%   -0.02%     
==========================================
  Files          31       31              
  Lines        2770     2768       -2     
  Branches      518      518              
==========================================
- Hits         2287     2285       -2     
  Misses        346      346              
  Partials      137      137              

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