Update AGENTS.md and SKILL.md to refine testing policies and clarify project-specific test execution. Emphasized the importance of using filters for tests and avoiding full solution runs unless necessary. Adjusted descriptions in phase-work and side-work skills to align with the new testing guidelines.

AGENTS.md

@@ -35,13 +35,16 @@ dotnet build h-school.sln
 ```
 
 ```bash
-dotnet test
+dotnet test tests/HSchool.People.Tests --filter FullyQualifiedName~YearlyIntake
 ```
 
 ```bash
-npm --prefix src/HSchool.Client test
+npm --prefix src/HSchool.Client test -- src/ui/peoplePanel.test.ts
 ```
 
+Solution-wide `dotnet test` and a full client `npm test` are CI, or when the user asked. Agents
+scope the run — Testing policy.
+
 ```bash
 npm --prefix src/HSchool.Client run build
 ```
@@ -115,6 +118,12 @@ say so explicitly in the change description.
 
 ## Testing policy
 
+**What to run.** One project from the list below, filtered to the new or changed class while
+iterating. Client Vitest only if `src/HSchool.Client` changed. `HSchool.AppHost.Tests` only if
+the change is HTTP, WebSocket, or host wiring — it boots a server. Do not `dotnet test` the
+solution, do not run client and .NET together "to be sure", do not re-run after a merge that
+only resolved a status line. Solution-wide is CI.
+
 - Simulation changes need a `GameClock` or `SchoolRegistry` test. They are fast and need no host.
   Putting a roster into `World` and ticking needs belongs there too.
 - People generation belongs in `tests/HSchool.People.Tests`. Same seed, map, country and