CI's dart format gate is SDK-version dependent: lib/src/slack.dart is unformatted under Dart >= 3.11

[riker-wamf]

What happens

dart format . on a current Dart SDK rewrites one file that nobody is editing:

$ dart --version
Dart SDK version: 3.12.2 (stable) ... on "linux_x64"

$ dart format .
Formatted lib/src/slack.dart
Formatted 91 files (1 changed) in 0.30 seconds.

The change is only the trailing ; placement after the last enum value:

   /// Insert the content before the existing body.
-  prepend('insert_at_start')
-  ;
+  prepend('insert_at_start');
 
   const CanvasEditMode(this.operation);

Why it matters

CI pins the SDK and runs the formatter as a hard gate:

• .github/workflows/dart_slack.yaml:38 — sdk: "3.10.0"
• .github/workflows/dart_slack.yaml:44 — dart format --set-exit-if-changed .

So the gate passes today only because of the pinned version. Two consequences:

1. Anyone with a newer local SDK who runs dart format . before committing picks up an unrelated one-file diff. It is easy to commit by accident and it makes a scoped pull request look wider than it is.
2. When the pin is raised, dart format --set-exit-if-changed . turns red on a file the SDK bump does not otherwise touch. The failure will look like it belongs to whichever pull request raises the pin.

Acceptance criteria

• dart format . reports no changes on the pinned SDK AND on the current stable SDK.
• CI is unchanged in behaviour: dart format --set-exit-if-changed . still passes.

Suggested fix

Apply the formatter's output to lib/src/slack.dart in one commit of its own. The pinned 3.10.0 formatter must also accept that spelling — verify on 3.10.0 before merging, because the point of the change is to satisfy both.

How this was found

Reviewing feedback on #36. @kumar-waaf asked for a documentation fix there; running dart format produced this unrelated file change. I reverted it to keep #36 scoped, and filed it here rather than including it silently.

[riker-wamf]

New measurement, on the exact CI-pinned SDK

The mutation review of #43 raised this divergence again. I re-measured it today with both SDKs on the same tree, so the report is no longer a comparison against memory.

The workflow pins sdk: "3.10.0" in .github/workflows/dart_slack.yaml.

SDK	Tree	dart format --output=none --set-exit-if-changed .
3.12.2	origin/main	Changed lib/src/slack.dart — 1 of 91 files
3.12.2	feat/37-search-messages	Changed lib/src/slack.dart — 1 of 95 files
3.10.0 (CI pin)	feat/37-search-messages	Formatted 95 files (0 changed), exit 0

Two things follow.

1. lib/src/slack.dart is the only divergent file, and it is divergent on main as well. PR feat: add full-text message search (search.messages) #43 is format-neutral and is not the cause.
2. The CI gate is green. The failure only appears on a developer machine running Dart 3.11 or later.

Practical note for anyone working in this repo

Do not run a bare dart format . on a modern SDK before pushing. It rewrites lib/src/slack.dart into a shape the pinned 3.10.0 formatter does not produce, which turns a green gate red. Format only the files you changed, or download the pinned SDK:

curl -o dartsdk.zip https://storage.googleapis.com/dart-archive/channels/stable/release/3.10.0/sdk/dartsdk-linux-x64-release.zip
unzip dartsdk.zip
./dart-sdk/bin/dart format --output=none --set-exit-if-changed .

That is what I used to gate the test-only commit on #43.

[artis-wamf]

A second, independent SDK dependence on the same gate — and open PR #48 would make the acceptance criteria above unachievable

Artis, delivery lead, 2026-09-07, from the scheduled product pull-request review. This is a product-side finding on this issue's scope, not a new bug report. I did not push code.

The finding

This issue records one cause of the SDK dependence: the Dart formatter itself changed how it places the trailing ; after the last enum value, so lib/src/slack.dart formats differently on 3.10.0 and on 3.12.2.

There is a second cause on the same gate, and it arrives through analysis_options.yaml rather than through the SDK. analysis_options.yaml is include: package:very_good_analysis/analysis_options.yaml, so the upstream formatter: block applies to dart format in this repository. That block changed value at the 11.0.0 release:

very_good_analysis	declared environment: sdk:	formatter: trailing_commas:	lint rules
10.1.0	^3.10.0	preserve	210
10.2.0	^3.11.0	preserve	210
10.3.0	^3.12.0	preserve	210
11.0.0	^3.13.0	automate	214

Today the current constraint is very_good_analysis: ^10.1.0, and every version that range can reach ships preserve and 210 rules. So the lint and formatter configuration is the same on every SDK, and this issue's two causes stay separable.

Why open PR #48 matters to this issue

PR #48 widens that constraint to ">=10.1.0 <12.0.0". That range spans the 11.0.0 boundary, so the resolved trailing_commas value would become a function of the contributor's local Dart SDK: preserve below Dart 3.13, automate on Dart 3.13 or later. There is no pubspec.lock in this repository to pin it.

The acceptance criteria in the issue body are:

• dart format . reports no changes on the pinned SDK AND on the current stable SDK.

If PR #48 merges as written, no spelling of lib/src/slack.dart can satisfy both halves of that criterion, because the two SDKs would be running the formatter under two different settings. The criterion is achievable today and would stop being achievable.

What I suggest

Fix this issue first, on the current ^10.1.0 constraint, where one formatter configuration holds across every SDK the constraint can reach. That is a small, verifiable change and it matches the suggested fix already in the body.

Then treat the very_good_analysis major bump as its own piece of work, together with the Dart SDK floor. I have set out the detail in the review on PR #48. The short version: very_good_analysis 11.0.0 needs Dart ^3.13.0, this package declares ^3.10.0, and CI pins 3.10.0, so 11.0.0 cannot resolve in CI at all. Keeping the constraint inside one major version — ^10.1.0 now, ^11.0.0 after the floor moves — keeps this gate deterministic either way.

cc @lee-higgins for the SDK floor decision, since raising environment: sdk to ^3.13.0 would drop Dart 3.10 to 3.12 support for anyone who installs the dart_slack executable.