refactor(domain): Consolidate Flag mutation methods by concern — Phase 2

[amodelandme]

Summary

Replaces the trio Flag.SetEnabled / Flag.UpdateStrategy / Flag.Update with a single concern-named mutation Flag.Reconfigure(bool, RolloutStrategy, StrategyConfig). The two field-shaped methods had no production callers — deleting them removes a partial-mutation bug class (toggle enabled while leaving a now-mismatched strategy behind). The atomic Update method is renamed to Reconfigure to declare full replacement, not partial patching. UpdateName and Archive are unchanged. Public HTTP API, DTOs, and IBanderasService signatures are byte-for-byte identical to before.

Changes in this PR

• Domain + Application — Flag.cs deletes SetEnabled and UpdateStrategy; renames Update → Reconfigure with a concern-named XML doc. BanderasService.UpdateFlagAsync adopts the new method name (one line).
• Tests — drop deleted-method tests, rename Update* test methods to Reconfigure*, remove the redundant UpdateStrategy mismatch test, and update the optimistic concurrency integration test to race Reconfigure against UpdateName.
• Docs — spec + implementation notes added under Docs/Decisions/refactor-flag-mutation-consolidation/. Foundation docs updated: architecture.md (Domain Integrity principle + GET-query environment-validation ratification), current-state.md (phase status, archived-terminal note, test counts, 2026-05-11 Lessons Learned), roadmap.md (Phase 2 checkbox + progress sentence), flag-ddd-analysis-backlog.md (backlog item checked off).

Spec

Docs/Decisions/refactor-flag-mutation-consolidation/spec.md

Implementation Notes

Docs/Decisions/refactor-flag-mutation-consolidation/implementation-notes.md

Definition of Done

• SetEnabled and UpdateStrategy removed from Flag.cs
• Update renamed to Reconfigure; XML doc rewritten to name the concern
• BanderasService.UpdateFlagAsync calls flag.Reconfigure(...)
• No file in repo (excluding the spec) references flag.SetEnabled(, flag.UpdateStrategy(, or flag.Update( — verified by grep
• FlagArchivedInvariantTests covers Reconfigure, UpdateName, Archive; deleted method tests removed
• StrategyConfigTests references Reconfigure only; redundant UpdateStrategy mismatch test removed
• FlagConcurrencyTokenTests continues to demonstrate the optimistic concurrency contract
• dotnet build -p:TreatWarningsAsErrors=true succeeds across all projects (0 warnings / 0 errors)
• dotnet csharpier check . reports no violations (104 files checked)
• All unit tests pass (153/153 — 5 fewer than baseline, all due to deleted-method coverage being folded)
• All integration tests pass (54/54, count unchanged)
• Requests/smoke-test.http unchanged; PUT /api/flags/{name} returns the same 200 OK FlagResponse
• DDD backlog item Consolidate SetEnabled() + UpdateStrategy() + Update() checked off in Docs/Decisions/flag-ddd-analysis-backlog.md

Testing

Domain unit tests (cover AC-1 through AC-5):

dotnet test Banderas.Tests/Banderas.Tests.csproj \
  --filter "FullyQualifiedName~FlagArchivedInvariantTests|FullyQualifiedName~StrategyConfigTests"

Expected: all archived-guard, success, and config-mismatch tests pass; no test references SetEnabled or UpdateStrategy.

Integration suite (covers AC-6 byte-for-byte API parity and AC-7 optimistic concurrency):

dotnet test Banderas.Tests.Integration/Banderas.Tests.Integration.csproj

Expected: 54/54 green. FlagConcurrencyTokenTests.ConcurrentUpdate_SecondSave_ThrowsFlagConcurrencyExceptionAsync demonstrates the optimistic concurrency contract via Reconfigure + UpdateName.

Manual smoke (no expected change vs. baseline):

curl -X PUT http://localhost:5051/api/flags/checkout-flow \
  -H "Content-Type: application/json" \
  -d '{"environment":"Development","isEnabled":true,"strategyType":"None","strategyConfig":null}'

Expected: 200 OK with FlagResponse body, identical to the pre-refactor baseline.

Static check that no caller revived a deleted method:

grep -rn "\.SetEnabled(\|\.UpdateStrategy(\|flag\.Update(" --include="*.cs" .

Expected: zero hits.