[FreeApophis]

Stacked on #1013 (fix-all-using-insertion). Retarget to main after #1013 merges; the diff then shows only this commit.

Closes #1020

What

The λ1012 code fix (prefer …OrNone() over …OrDefault() with a null check) inserted using Funcky.Extensions; through its own path with the default BatchFixer, so three or more diagnostics in one document that all needed the directive collided and some were only rewritten by a second Fix-All pass, the same defect as #1009.

PreferOrNoneCodeFix now derives from the ExtensionMemberCodeFix base introduced by #1013: document-based Fix-All provider, all flagged calls of a document rewritten at once, the directive added once. Titles and the single-fix behaviour are unchanged.

Notes for the review

• The λ1012 rewrite replaces the whole xs.FirstOrDefault() ?? fallback coalesce with xs.FirstOrNone().GetOrElse(fallback). ExtensionMemberRewrite(Original, Replacement) covers that as-is (Original is the coalesce), no change to the base.
• The only deviation is the binding probe: the base's default predicate IsDeclaredInFunckyExtensions checks the symbol of the whole replacement, which here is Option<T>.GetOrElse in Funcky.Monads, so it would always add the using. The fix overrides TryApplyAsync with symbol is IMethodSymbol: GetOrElse only binds when its …OrNone() receiver binds, which needs the directive. This corresponds to the old IsExtensionsNamespaceImported check; the old code also accepted a non-empty CandidateSymbols set, which the base's Func<ISymbol?, bool> cannot see. No existing test needed it.
• Test first: ThreeFixesThatAllNeedTheUsingAreAppliedInOnePass (four fixes, file-level usings) and ThreeFixesInANamespaceThatAllNeedTheUsingAreAppliedInOnePass (three fixes, usings inside the namespace) both failed on the base branch with Expected '1' iterations but found '2' iterations., confirming the defect.
• dotnet build Funcky.slnx -warnaserror clean, analyzer tests 248/248 green.
• Changelog: the Fix-All needs a second pass when three or more extension-form fixes add the same using #1009 bullet under Analyzers (Funcky.Analyzers 2.1.0) now lists λ1012 and references λ1012 code fix: Fix-All needs a second pass when three or more fixes add the same using #1020.

🤖 Generated with Claude Code

[Copilot]

🟢 Approval recommended

No active review issues are reported for the λ1012 migration to the shared Fix-All infrastructure.

No open issues 🎉

What changed in this PR

Moves the λ1012 code fix onto the shared ExtensionMemberCodeFix infrastructure from #1013, addressing #1020 by avoiding conflicting using-directive insertions during Fix-All.

Changes:

• Reuses document-based Fix-All to rewrite eligible calls together and add using Funcky.Extensions; once per using container.
• Adds regression tests for multiple fixes with file-level and namespace-level usings.
• Updates the changelog to include λ1012 in the Fix-All correction.

File	Description
Funcky.Analyzers/​Funcky.Analyzers.Test/​OrNone/​PreferOrNoneTest.cs	Adds one-pass Fix-All regression tests for both using placements.
Funcky.Analyzers/​Funcky.Analyzers.CodeFixes/​OrNone/​PreferOrNoneCodeFix.cs	Adopts the shared base with a binding predicate tailored to GetOrElse.
changelog.md	Adds λ1012 and #1020 to the shared Fix-All release note.

_{Review effort: Balanced}