Dotnet Fix

---
name: dotnet-fix
description: "[Development] Implement a minimal, idiomatic .NET 10 / C# fix in a single Virto Commerce module (or vc-platform) that turns the reproduction test green while preserving BL-* invariants and leaving existing tests untouched. Used by the fullstack-backend developer agent in /qa-fix (Gate 3)."
---

# /dotnet-fix — Implement a minimal C# fix in a VC module

Turn the red reproduction test (`/dotnet-unit-test`) green with the **smallest correct change**, then
pass the build/test gate. This is **Gate 3** of `.claude/rules/quality-gates.md`.

## Preconditions
- Source checked out in `.fix-workspace/<repo>/` on branch `claude/qa-autofix/VCST-XXXX`.
- A NEW failing test exists (Gate 2) or trivial-skip is justified.

## Steps
1. **Understand the seam** (controller → service → domain → repo → events). Confirm the real
   root cause, not a symptom. See `knowledge/architecture/vc-module-architecture.md`.
2. **Implement the smallest correct change** to production code only. See `fix-patterns.md` and
   `dotnet10-best-practices.md`. Match the repo's existing style. Two build-hygiene facts that bite:
   - `TreatWarningsAsErrors=true` in every module's `Directory.Build.props` — a new warning in your
     fix **fails the build**. Fix the warning, never suppress.
   - NuGet audit makes vanilla `dotnet` commands fail even on clean checkouts (NU1903) — append
     `-p:NuGetAudit=false` to every command, CLI-only, never edit build props.
3. **Green — fast inner loop first** (repro test only), then the full project:
   ```
   dotnet test tests/VirtoCommerce.<Name>.Tests --nologo -p:NuGetAudit=false --filter "FullyQualifiedName~VCST1234"
   dotnet test tests/VirtoCommerce.<Name>.Tests --nologo -p:NuGetAudit=false
   ```
   Repro test passes; **ALL pre-existing tests still pass and are UNMODIFIED**.
4. **Gate — full build + tests:**
   ```
   dotnet build -c Debug -p:NuGetAudit=false
   dotnet test tests/VirtoCommerce.<Name>.Tests --nologo -p:NuGetAudit=false
   ```
   (vc-platform: build the solution but test only the affected test project — never `dotnet test` at
   the platform root.) These mirror `repoProfile` commands from `ci/lib/repo-router.ts`.
5. **Self-scan the diff** (`git diff`) for accidental churn — formatting, usings, unrelated files —
   then hand it to `backend-reviewer` (Gate 4) before any PR is opened.

## Hard rules (a violation = STOP, not "push anyway")
- **Single repo.** All changed files in ONE `vc-module-*` (C# and/or its `Web/Scripts/` Admin UI).
  Root cause in a NuGet dependency → cross-module → STOP (`ROOT_CAUSE: belongs in <dep>`).
- **Minimal diff.** No refactors, no NuGet adds/upgrades (incl. test packages — FluentAssertions
  stays on 7.x), no formatting churn, no unrelated files.
- **Never modify/delete existing tests** — only ADD. An existing test going red = contract conflict → STOP.
- **Never touch** secrets, connection strings, `*.Development.json`, CI config, `Directory.Build.props`.
  Generated migrations are high-risk — if the fix truly needs one, flag loudly (may warrant a BAIL-back).
- **Preserve BL-* invariants** (`business-logic.md`). A fix that passes the STR but breaks a `BL-*`
  rule is a regression — reject it.
- If the correct fix is unclear or risky → `FIX_STATUS: FAILED`, don't push speculative changes.

## References
- `fix-patterns.md` — common VC fix shapes (null-guard, mapping, cascade, RBAC, async)
- `dotnet10-best-practices.md` — modern C# idioms + build hygiene within a minimal diff
- `.claude/rules/quality-gates.md` — G3 (green), G4 (review), G5 (build/CI), G7 (no auto-merge)
- `knowledge/oracles/vc-bug-catalog.md` — don't re-introduce a historical failure pattern