re0-style

1Fix a named change or set of files to match the conventions its repository already keeps, changing style and nothing else.
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3## Goal
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5Code written in one session drifts from the code around it: another quote style, another naming case, imports in another order, errors raised the way the last project raised them. A reader then has to work out whether each difference means something. `re0-style` makes the code in scope read like its neighbours. It takes every convention from the repository itself, first from the formatter and linter the project configures and then from the pattern neighbouring files follow for what no tool decides, and applies the fixes in place with behavior unchanged. Where the repository itself is split between two conventions, it asks rather than picks. The result is a style-only diff and a report of each change by file and rule.
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7## Workflow
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91. **Pin the scope.** Name the change (the working diff, or the diff against the base the user names) or the file list the user gave. For a change, the unit is the changed lines: a file the change does not touch is out of scope, and so are the untouched lines of a file it does. Run the project's tests once now, by the command its manifest, task runner or CI workflow names, and record the result, so a failure that was already there is not blamed on the pass.
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