CI: get development green and run the tests in ~7 minutes (#132: CI-0, CI-12, CI-1/2/3)

[Cadacious]

Gets development green and fast. This is the first PR for #132 and covers CI-0 and CI-12, plus the parts of CI-1, CI-2 and CI-3 that live in the same workflow. CI-4 through CI-11 aren't included.

Result: the full suite (2,613 tests) passes in about 7 minutes of wall time. In one process it takes about 56 minutes on a hosted runner, and today it never finishes because the runner is lost. This was measured on a fork of this repo with these exact commits (run).

Two commits

1. Get the test suite passing on Linux in bounded memory (CI-0)

• LoginPacket.Read rejects trailing bytes with EnsureFullyConsumed. AuthLoginRejectsTrailingBytes has expected this since Complete mission runtime and Bootcamp workflows #96.
• MissionReviewFindingTests builds its paths with Path.Combine. The @"src\…" literals were file names with backslashes in them on Linux.
• Tests read each navmesh once per process. The new TestSupport/TestNavMeshes.cs hands every harness its own NavMeshQuery over a shared mesh. Nothing in the game edits tiles after a load. Before, every Wilderness harness read its own 15 MB mesh, and the whole suite in one process grew past 12 GB. Now it peaks at about 1.4 GB. Production code is unchanged.
• Two tests are quarantined, each with [Ignore], a [GitHubWorkItem] and a comment on why. Both failed intermittently on loaded CI runners.
  • ForeanEscortsCanFollowFromTheCaveExitToTheReclaimedBase depends on real time. Creature timers (buffs, bombs, habits) run on Environment.TickCount64, so how far the escort gets in 1,200 simulated ticks depends on how fast the machine runs them. It also fails every time in class order on Windows. It needs an injectable clock, which is a bigger change than this PR.
  • ConcurrentDeadlineEvaluationCommitsOneCompletion catches a real race. It failed 2 times in about 9 full runs, with expected: 1, actual: 0. SceneApplication.Tick takes due timers from SceneDueQueue (a PriorityQueue plus a Dictionary, with no locking) outside _dispatchGate. So two overlapping deadline evaluations can both see the same due item, and each then skips it after the other's removal: the deadline is dropped and neither commits. It passed 48 of 48 times locally, because the threads rarely overlap on an idle machine. The fix belongs in the scene host's locking, not in a CI PR. It deserves its own issue.

2. Run the tests in parallel lanes across runners

dotnet.yml now has four jobs:

Job	What it does
detect code changes	Lists the PR's files. If every one is docs (*.md, docs/, .github/agents/, .claude/), the build and tests are skipped. Anything in doubt runs everything.
build	Restores and builds once. Plans the test lanes and hands the build to the test runners as one artifact. The NuGet cache is restored on every run and saved only from development, because a PR's cache can only be read by that PR and the 10 GB limit evicts the oldest first.
test (0) … test (7)	Each of 8 runners runs 2 test processes ("lanes") side by side. Each lane is its own test host, so no static state is shared. Each has a 10-minute hang dump, a GC heap cap (so an overgrown host fails with a stack trace instead of losing the runner), and TRX results uploaded.
tests complete	The one check to require (CI-10). It totals every lane's results and fails unless the build and every runner passed. On a docs-only PR it passes without them. The skip uses job conditions, not paths-ignore, so this check always reports.

Also: ubuntu-24.04, a timeout on every job, checkout@v7, setup-dotnet@v6, a read-only token by default, and a new push to a PR cancels that PR's older run. Runs on development are never cancelled, since a cancelled run saves no cache and leaves no timings.

How the lanes are planned: .github/scripts/TestShards.cs runs with dotnet run and needs no packages.

• Finding tests: it reads the built Rasa.Test.dll with System.Reflection.Metadata and lists every [TestMethod] on every [TestClass].
• Assigning them: tests are dealt out slowest first, each to the least-loaded lane. Durations are averaged over the last 3 green runs on development. A PR whose base has none uses its own green runs, and with neither it balances on test-case counts.
• Splitting big classes: a class bigger than half a lane's share is split by method, with a method's data rows kept together. Without this, MissionDialogueTests alone (about 4.8 minutes) would set the run's length.
• Nothing can be dropped: every lane but the last lists what it runs, and the last lane runs everything the others don't list. A test the planner misses, or one added since the timings were recorded, still runs exactly once.
• Visibility: the plan is printed in the build job's summary.

Where this differs from #132

• Balanced on measured time, not hashed by class name. With hashing, the slowest shard came out about 50% over the ideal on this suite. Balancing on measured time hits the ideal.

• No "listed total equals TRX total" check. dotnet test --list-tests reports 2,492 tests while the TRX files contain 2,613, because data rows are counted differently. So that comparison would fail on a correct run. The "last lane runs the rest" rule makes completeness hold by construction instead.

• Lanes per runner. A hosted runner has 4 vCPUs, and the suite runs one test at a time. These are measured contention numbers from fork runs:

  Lanes per runner	Each test, vs. alone	Work per runner, vs. one process
  2	about 1.1× slower	about 1.8×
  3	about 1.4× slower	about 2.1×
  4	about 1.8× slower	about 2.2×

  A runner behaves like about 2 cores. 8 runners × 2 lanes is the fastest configuration and keeps clock-sensitive tests close to their unloaded speed. It uses 11 jobs per run, inside the Free plan's 20 concurrent jobs. Both numbers are env settings at the top of the workflow.

• Debug is kept, as today. That's open question 4 in CI modernization: get development green, then make it stay green #132, and the build configuration is a one-word change.

• master stays in the push triggers. That's CI-11, a maintainer decision.

Verified on the fork

All of these ran with this workflow on SandboxServers/Rasa.NET:

• These exact commits, pushed to development: green, 2,613 results (the 2 quarantined tests skipped), 7.4 minutes (run).
• A PR run: the NuGet cache restored and not saved, 7.1 minutes (run).
• A push to development: "Cache saved", and its timings used by later runs (run).
• A PR changing only docs/setup.md: build and tests skipped, tests complete passed (run).

Worth knowing

• The memory retention itself isn't fixed. Loading the navmesh once removed most of the cost, but earlier tests' worlds are still kept alive by something static. CI modernization: get development green, then make it stay green #132's memory section has the gcroot step to find it.
• After merging: require tests complete on development once it has been green for a week (CI-10).

Refs #132.

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