ci(coverage): exclude generated EF migrations to stop coverage OOM (exit 137)

The shared Build & test job OOM-killed (exit 137) with coverage enabled: the
whole-solution Architecture.Tests process instruments both EF migration folders
(~2.59M generated lines vs ~200k authored), ballooning coverlet's in-memory
hit-count arrays past the runner's limit.

Add coverlet.runsettings excluding **/Migrations/*.cs (+ generated/compiler
attributes) and pass it via --settings on the Test step. This cuts the
instrumented surface ~126x (2,510,185 -> 19,963 coverable lines in the
Architecture.Tests process, verified locally) and makes the reported percentage
reflect authored code. Documented in docs/ci-cd.md.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.gitea/workflows/docker-build.yml

@@ -103,7 +103,7 @@ jobs:
       - name: Test
         run: >-
           dotnet test --configuration Release --no-build --blame-hang-timeout "2m" --verbosity normal
-          --collect:"XPlat Code Coverage" --results-directory ./coverage
+          --collect:"XPlat Code Coverage" --settings coverlet.runsettings --results-directory ./coverage
 
       # Coverage reporting (ersatztv#15 scope item 4): coverlet.collector emits a Cobertura report
       # per test project (via --collect above); ReportGenerator merges them into a human-readable

coverlet.runsettings

@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  Coverage collector config (ersatztv#15). Passed to dotnet test via
+  "settings coverlet.runsettings" alongside collect:"XPlat Code Coverage".
+  The two EF Core migration folders are ~2.59M lines of generated snapshot code
+  (vs ~200k lines of authored code); instrumenting them balloons coverlet memory
+  and OOM killed the shared Build and test job (exit 137). Excluding generated
+  migration code bounds memory and makes the reported percentage reflect authored
+  code. Keep this comment free of double hyphens (invalid in XML comments).
+-->
+<RunSettings>
+  <DataCollectionRunSettings>
+    <DataCollectors>
+      <DataCollector friendlyName="XPlat Code Coverage">
+        <Configuration>
+          <ExcludeByFile>**/Migrations/*.cs</ExcludeByFile>
+          <ExcludeByAttribute>GeneratedCodeAttribute,CompilerGeneratedAttribute,ExcludeFromCodeCoverageAttribute</ExcludeByAttribute>
+          <Exclude>[*]*.Migrations.*</Exclude>
+          <SkipAutoProps>true</SkipAutoProps>
+        </Configuration>
+      </DataCollector>
+    </DataCollectors>
+  </DataCollectionRunSettings>
+</RunSettings>

docs/ci-cd.md

@@ -96,11 +96,17 @@ Docker build) → `dotnet build -c Release` → `dotnet test -c Release --no-bui
 the image build.
 
 - **Code coverage** (ersatztv#15): `dotnet test` runs with `--collect:"XPlat Code Coverage"
-  --results-directory ./coverage`, so `coverlet.collector` (referenced by every `*.Tests`
-  project) emits a Cobertura report per project. A follow-up **Coverage summary** step merges
-  them with ReportGenerator (`TextSummary` to the log, `MarkdownSummaryGithub` to the job step
-  summary). No floor is enforced yet ("decide on a floor later" — #15); the step is
-  `continue-on-error: true`, so a missing report or a transient tool install never blocks a build.
+  --settings coverlet.runsettings --results-directory ./coverage`, so `coverlet.collector`
+  (referenced by every `*.Tests` project) emits a Cobertura report per project. A follow-up
+  **Coverage summary** step merges them with ReportGenerator (`TextSummary` to the log,
+  `MarkdownSummaryGithub` to the job step summary). No floor is enforced yet ("decide on a
+  floor later" — #15); the step is `continue-on-error: true`, so a missing report or a
+  transient tool install never blocks a build.
+  - **`coverlet.runsettings` excludes generated EF migration code** (`**/Migrations/*.cs`,
+    ~2.59M generated lines vs ~200k authored). Instrumenting it OOM-killed the shared `test`
+    job (exit 137); excluding it cuts the instrumented surface ~126× (2.5M→20k coverable
+    lines in the whole-solution `Architecture.Tests` process) and makes the percentage reflect
+    authored code.
 - **Shallow checkout**: `fetch-depth: 1` (ersatztv#190) — this job never runs `git
   describe`/`git log`, only `build` needs full history/tags for version computation, so
   `test` and `migrations` both check out shallow. `build`'s checkout stays `fetch-depth: 0`.