Add payload serializer guardrails

README.md

@@ -101,8 +101,9 @@ dotnet dotnet-ef migrations add <MigrationName> --project RpgRoller/RpgRoller.cs
 - Browser interop is in `RpgRoller/wwwroot/js/rpgroller-api.js`.
 - Workspace reads are resolved server-side through scoped query services; browser interop remains for browser-only concerns such as session storage, SSE wiring, and DOM helpers.
 - Live workspace refreshes now compare separate roster, per-character sheet, and log versions so unrelated state changes do not force a full roster + sheet + log reload.
-- Workspace campaign data is loaded in bounded slices: visible campaign summaries, a selected campaign roster, a selected character sheet, and a 50-row incremental log window backed by `/api/campaigns/{campaignId}/log/page`.
+- Workspace campaign data is loaded in bounded slices: visible campaign summaries, a selected campaign roster, a selected character sheet, and a 25-row incremental log window backed by `/api/campaigns/{campaignId}/log/page`.
 - Campaign log rows now ship compact summary data first and lazy-load dice + breakdown detail through `/api/rolls/{rollId}` only when a row is expanded.
+- Hot API contracts share a source-generated `System.Text.Json` context, and HTTP JSON responses are gzip-compressed when the client advertises support.
 - OpenAPI contract source remains at `openapi/RpgRoller.json`.
 
 ## Test and Coverage
@@ -111,6 +112,7 @@ dotnet dotnet-ef migrations add <MigrationName> --project RpgRoller/RpgRoller.cs
   ```powershell
   dotnet test RpgRoller.Tests/RpgRoller.Tests.csproj --collect:"XPlat Code Coverage" --settings RpgRoller.Tests/coverlet.runsettings
   ```
+- Regression tests enforce payload budgets for the hottest contracts: character sheet reads, initial log page loads, incremental log updates, and roll mutation responses.
 - Coverage gate:
   ```powershell
   pwsh ./scripts/check-coverage.ps1 -MinLineRate 0.90 -MinBranchRate 0.70