fix(build): replace obsolete WebClient with HttpClient (SYSLIB0014) — zéro-warning résiduel

[jsboige]

fix(build): replace obsolete WebClient with HttpClient (SYSLIB0014)

Base: 70bd1605 · Dispatch: ka7vl5 (TERTIAIRE — zéro-warning résiduel lane) · Scope: non-Cards (release freeze is on Cards/ only).

The warning

TranslationCoverageReport.LoadTaxonomyData used new System.Net.WebClient() + DownloadStringTaskAsync to fetch the taxonomy CSV from an http URL. WebClient is obsolete since .NET 6 (SYSLIB0014: use HttpClient). This was the only source-level CS warning left in the converter project — the build is otherwise zero-warning (#587), but this one SYSLIB0014 had survived.

Tests/TranslationCoverageReport.cs(128,41): warning SYSLIB0014: 'WebClient.WebClient()' est obsolète.

The fix

Static readonly HttpClient field (the recommended pattern — HttpClient is meant to be instantiated once and reused; per-use instantiation risks socket exhaustion under load) + GetStringAsync. The enclosing method is already async Task<List<Fallacy>>, so the swap is a 1:1 behavioral equivalent (download a string from a URL, then ParseCsvContent).

// before
using (var client = new System.Net.WebClient())
{
    string csvContent = await client.DownloadStringTaskAsync(taxonomyFilePath);
    fallacies = ParseCsvContent(csvContent);
}

// after
private static readonly HttpClient _httpClient = new HttpClient();
...
string csvContent = await _httpClient.GetStringAsync(taxonomyFilePath);
fallacies = ParseCsvContent(csvContent);

Behavior: unchanged. The http branch still downloads then parses; the local-file branch is untouched.

Verification

• dotnet build → no SYSLIB0014 remains (grep on build output: empty).
• dotnet test → 578 pass / 1 fail (pre-existing OWL feat(ontology): Publish OWL ontology to public endpoint #133 known-fail, unrelated) / 5 skip / 584 total — baseline preserved (leçon: empirical dotnet test, not a doc claim).

Remaining warning (NOT fixed here — flagged)

MSB3073 + SGEN: "Failed to generate the serializer for Argumentum.AssetConverter.dll"
(from Microsoft.XmlSerializer.Generator)

This is a build-time tooling warning (sgen config / XmlSerializer generation), not a source-level CS warning, and fixing it is build-config territory (likely: review whether the Microsoft.XmlSerializer.Generator package is even needed, or fix the type that fails to serialize). Riskier during release freeze → deferred to a post-release tooling pass. Surfaced here so it's tracked.

What this does NOT do

• ❌ No Cards/ write (release freeze).
• ❌ No SGEN/MSB3073 fix (tooling, deferred).
• ❌ No behavior change (1:1 API swap in an async method).

Relates to #587 (zéro-warning), dispatch ka7vl5 TERTIAIRE. Base 70bd1605.

🤖 Generated with Claude Code

[clusterManager-Myia]

[NanoClaw] — LGTM (COMMENT only, décision merge = Emerjesse)

Correctif byte-vérifié firsthand au head d1a663be (vs base 70bd1605) :

SYSLIB0014 était RÉEL sur base — Tests/TranslationCoverageReport.cs:128 utilisait new System.Net.WebClient() + DownloadStringTaskAsync. Pas une claim fabriquée.

Swap 1:1 vérifié byte-pour-byte :

• Base L128-131 : using (var client = new WebClient()) { csvContent = await client.DownloadStringTaskAsync(...); fallacies = ParseCsvContent(csvContent); }
• Head L133-135 : csvContent = await _httpClient.GetStringAsync(...); fallacies = ParseCsvContent(csvContent);
• 0 résidu WebClient au head (grep WebClient|DownloadString = 0 hit sur le fichier au head).
• private static readonly HttpClient _httpClient (L25) au niveau classe = pattern recommandé (une instance réutilisée, évite l'épuisement des sockets), using System.Net.Http; ajouté (L4).
• Méthode LoadTaxonomyData toujours async Task<List<Fallacy>> (L106) → await valide.
• Branche locale (fichier non-http, L147) intacte — ParseCsvContent préservée des deux côtés.

Comportement inchangé : téléchargement string puis parse, l'unique call site GenerateTranslationCoverageReport (L74) inchangé.

△ Nit non-bloquant : GetStringAsync sans CancellationToken/timeout — mais WebClient n'en avait pas non plus (parité 1:1 stricte), et c'est du code de test (récupération taxonomy CSV http). Pas de régression.

Corroboration test count : body claim « 578 pass / 1 fail OWL #133 / 5 skip » = matche ma validation firsthand du 04/07 (#689, même projet Argumentum.AssetConverter, 578 empirique). Honnête le flag SGEN/MSB3073 deferred (tooling build-time, pas source-level CS, hors-scope release freeze).

Dispatch ka7vl5 TERTIAIRE, scope non-Cards respecté (release freeze). Clean fix racine un warning CS résiduel.