Pin the formatter, and stop it editing the record

The first CI run went red on `ruff format --check`, on a tree that was clean on
this machine. Three separate problems, all found by pushing.

`ruff>=0.4` is not a pin. CI installed 0.16.6 where the laptop had 0.15.18, and
0.16 formats Python code blocks inside Markdown while 0.15 leaves them alone — so
the two disagreed about whether the repository was formatted, which is the one
thing a formatter exists to settle. Pinned to the 0.16 line. Dependabot will
offer the next one, and CI will say whether it is safe.

The file it tripped over is `docs/survey-ui-consistency.md`, which quotes four
lines of a dialog call as it looked on 22 August. That excerpt is a fragment —
two arguments, no call around them — so the formatter parsed it as two statements
and rewrote them into a tuple and an assignment that never existed anywhere. The
surveys are dated records of a past state, so `docs/` is now excluded: a
formatter editing a quotation is not tidying, it is falsifying.

And the installer workflow was firing for branches it had no business building.
Dependabot opened three action bumps within a minute of the push; each one edits
`.github/workflows/installers.yml`, each matched its own path filter, and each
started a five-platform build. `branches: [main]` stops it.

Everything else was green on the first try, including the part that was actually
uncertain: all seven test legs passed, macOS among them, and the installers built
on Windows, macOS on Apple silicon, and Linux on both x64 and arm64 — so the
uConsole build works and the ARM runner was available after all.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.github/workflows/installers.yml

@@ -14,6 +14,10 @@ on:
   # Only when the packaging itself changes. Three operating systems is not something to
   # spend on every commit while the repository is private and minutes are metered.
   push:
+    # `main` only. Without this, every Dependabot branch that touches this file — which
+    # is every action bump — starts a five-platform build, and three of those legs are
+    # billed at 2x and 10x.
+    branches: [main]
     paths:
       - "packaging/**"
       - ".github/workflows/installers.yml"

CHANGELOG.md

@@ -9,6 +9,18 @@ allowed to change behaviour, not just add to it.
 
 ## [Unreleased]
 
+### Fixed
+
+- The formatter is pinned. `ruff>=0.4` meant CI installed a newer ruff than a laptop had,
+  and the two disagreed about whether the tree was clean — 0.16 formats Python blocks
+  inside Markdown and 0.15 doesn't, so the first CI run went red on a file that was fine
+  locally. An unpinned formatter isn't a gate.
+- `docs/` is out of ruff's reach. The survey documents quote code as it looked on a past
+  date, in fragments that were never whole programs; a formatter rewriting a quotation
+  edits the record.
+- The installer builds only run for `main`. Every Dependabot branch that bumped an action
+  touched the workflow file, matched its path filter, and started a five-platform build.
+
 ### Changed
 
 - The distribution is named `mesh-term`. PyPI prohibits `meshterm` (pypi/support#12162),

pyproject.toml

@@ -51,7 +51,10 @@ dependencies = [
 dev = [
     "pytest>=8.0",
     "pytest-asyncio>=0.23",
-    "ruff>=0.4",
+    # Pinned to a minor line, not floated. A formatter that drifts between machines is
+    # not a gate: 0.16 formats Python inside Markdown and 0.15 does not, so an
+    # unpinned `ruff>=0.4` had CI and a laptop disagreeing about a clean tree.
+    "ruff>=0.16.6,<0.17",
 ]
 
 [project.urls]
@@ -74,8 +77,12 @@ packages = ["meshterm"]
 [tool.ruff]
 line-length = 100
 target-version = "py310"
-# Helper scripts for the Claude skills; they are not part of the package.
-extend-exclude = [".claude"]
+# Helper scripts for the Claude skills; they are not part of the package. And `docs/`,
+# which holds dated survey documents: ruff formats Python blocks inside Markdown, and the
+# code they quote is an excerpt of how a file looked on a past date. Reformatting a
+# quotation edits the record — and the excerpts are call fragments, not whole programs, so
+# the formatter's idea of "fixed" turns them into something that was never there.
+extend-exclude = [".claude", "docs"]
 
 [tool.ruff.lint]
 select = ["E", "F", "I", "UP", "B", "D"]