refactor(server): extract the change-request step

.github/actions/setup-jj/action.yml

@@ -0,0 +1,42 @@
+name: Setup Jujutsu
+description: Install the jj CLI from the official jj-vcs release artifacts.
+
+inputs:
+  version:
+    description: Jujutsu release tag to install.
+    required: false
+    default: v0.46.0
+
+runs:
+  using: composite
+  steps:
+    - name: Install jj
+      shell: bash
+      env:
+        JJ_VERSION: ${{ inputs.version }}
+      run: |
+        set -euo pipefail
+
+        case "${JJ_VERSION}-${RUNNER_OS}-${RUNNER_ARCH}" in
+          v0.46.0-Linux-X64)
+            asset="jj-${JJ_VERSION}-x86_64-unknown-linux-musl.tar.gz"
+            sha256="fce0271158e665ceb82dc66c5eb95b1728649094e9133074f3b5baece345fc08"
+            ;;
+          *)
+            echo "No pinned jj checksum for ${JJ_VERSION}-${RUNNER_OS}-${RUNNER_ARCH}" >&2
+            exit 1
+            ;;
+        esac
+
+        install_dir="${RUNNER_TEMP}/jj-${JJ_VERSION}"
+        mkdir -p "$install_dir"
+
+        curl -fsSL \
+          "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/jj-vcs/jj/releases/download/${JJ_VERSION}/${asset}" \
+          -o "${RUNNER_TEMP}/${asset}"
+        echo "${sha256}  ${RUNNER_TEMP}/${asset}" | sha256sum --check --status
+        tar -xzf "${RUNNER_TEMP}/${asset}" -C "$install_dir"
+
+        chmod +x "${install_dir}/jj"
+        echo "$install_dir" >> "$GITHUB_PATH"
+        "${install_dir}/jj" --version

.github/workflows/ci.yml

@@ -332,6 +332,11 @@ jobs:
         if: steps.changes.outputs.test_server != 'false'
         uses: ./.github/actions/setup-ci-deps
 
+      # The jj suites in apps/server/src/jj and apps/server/src/vcs skip themselves when jj is absent,
+      # so this step is what makes them actually run.
+      - uses: ./.github/actions/setup-jj
+        if: steps.changes.outputs.test_server != 'false'
+
       # No Electron setup here: `t3` (apps/server) has no Electron dependency
       # and none of its tests touch the runtime. Only the non-server `test`
       # job, which covers @t3tools/desktop, needs the download.

.github/workflows/release.yml

@@ -337,6 +337,8 @@ jobs:
       - name: Install Chromium for server browser integration tests
         run: node apps/server/node_modules/playwright-core/cli.js install --with-deps --only-shell chromium
 
+      - uses: ./.github/actions/setup-jj
+
       - name: Test
         run: vp run --filter t3 test --shard ${{ matrix.shard }}/${{ strategy.job-total }}
 

apps/server/src/checkpointing/CheckpointStore.test.ts

@@ -102,13 +102,13 @@ function buildLargeText(lineCount = 5_000): string {
 }
 
 it.layer(layerTest)("CheckpointStore.layer", (it) => {
-  describe("isGitRepository", () => {
-    it.effect("returns false when no Git repository is detected", () =>
+  describe("supportsCheckpoints", () => {
+    it.effect("returns false when no repository is detected", () =>
       Effect.gen(function* () {
         const tmp = yield* makeTmpDir();
         const checkpointStore = yield* CheckpointStore.CheckpointStore;
 
-        expect(yield* checkpointStore.isGitRepository(tmp)).toBe(false);
+        expect(yield* checkpointStore.supportsCheckpoints(tmp)).toBe(false);
       }),
     );
 
@@ -118,7 +118,7 @@ it.layer(layerTest)("CheckpointStore.layer", (it) => {
         yield* initRepoWithCommit(tmp);
         const checkpointStore = yield* CheckpointStore.CheckpointStore;
 
-        expect(yield* checkpointStore.isGitRepository(tmp)).toBe(true);
+        expect(yield* checkpointStore.supportsCheckpoints(tmp)).toBe(true);
       }),
     );
   });
@@ -131,7 +131,29 @@ it.layer(layerTest)("CheckpointStore.layer", (it) => {
       const nested = NodePath.join(tmp, "packages", "nested");
       yield* fileSystem.makeDirectory(nested, { recursive: true });
       const checkpointStore = yield* CheckpointStore.CheckpointStore;
-      expect(yield* checkpointStore.isGitRepository(nested)).toBe(true);
+      expect(yield* checkpointStore.supportsCheckpoints(nested)).toBe(true);
+    }),
+  );
+
+  it.effect("resolves checkpoint operations without overriding the registry selection", () =>
+    Effect.gen(function* () {
+      const cwd = yield* makeTmpDir();
+      yield* initRepoWithCommit(cwd);
+      const registry = yield* VcsDriverRegistry.VcsDriverRegistry;
+      const resolutions: VcsDriverRegistry.VcsDriverResolveInput[] = [];
+      const store = yield* CheckpointStore.make.pipe(
+        Effect.provideService(VcsDriverRegistry.VcsDriverRegistry, {
+          ...registry,
+          resolve: (input) => {
+            resolutions.push(input);
+            return registry.resolve(input);
+          },
+        }),
+      );
+      const checkpointRef = checkpointRefForThreadTurn(ThreadId.make("registry-selection"), 0);
+      yield* store.captureCheckpoint({ cwd, checkpointRef });
+      expect(resolutions).toEqual([{ cwd }]);
+      expect(yield* store.hasCheckpointRef({ cwd, checkpointRef })).toBe(true);
     }),
   );
   describe("diffCheckpoints", () => {

apps/server/src/checkpointing/CheckpointStore.ts

@@ -6,6 +6,7 @@ import * as Layer from "effect/Layer";
 import type { CheckpointStoreError } from "./Errors.ts";
 import type { VcsCheckpointOps } from "../vcs/VcsDriver.ts";
 import * as VcsDriverRegistry from "../vcs/VcsDriverRegistry.ts";
+import { JJ_REPOSITORY_DETECTION_ENABLED } from "../vcs/JjRepo.ts";
 
 export interface CaptureCheckpointInput {
   readonly cwd: string;
@@ -43,7 +44,7 @@ export interface DeleteCheckpointRefsInput {
 export class CheckpointStore extends Context.Service<
   CheckpointStore,
   {
-    readonly isGitRepository: (cwd: string) => Effect.Effect<boolean, CheckpointStoreError>;
+    readonly supportsCheckpoints: (cwd: string) => Effect.Effect<boolean, CheckpointStoreError>;
 
     readonly captureCheckpoint: (
       input: CaptureCheckpointInput,
@@ -94,10 +95,19 @@ export const make = Effect.gen(function* () {
     return handle.driver.checkpoints satisfies VcsCheckpointOps;
   });
 
-  const isGitRepository: CheckpointStore["Service"]["isGitRepository"] = (cwd) =>
-    vcsRegistry
-      .detect({ cwd, requestedKind: "git" })
-      .pipe(Effect.map((repository) => repository !== null));
+  const supportsCheckpoints: CheckpointStore["Service"]["supportsCheckpoints"] = Effect.fn(
+    "CheckpointStore.supportsCheckpoints",
+  )(function* (cwd: string) {
+    const handle = yield* vcsRegistry.detect({
+      cwd,
+      ...(!JJ_REPOSITORY_DETECTION_ENABLED ? { requestedKind: "git" as const } : {}),
+    });
+    if (!handle?.driver.checkpoints) {
+      return false;
+    }
+    const usable = handle.driver.checkpointsUsable;
+    return usable ? yield* usable(cwd) : true;
+  });
 
   const captureCheckpoint: CheckpointStore["Service"]["captureCheckpoint"] = Effect.fn(
     "captureCheckpoint",
@@ -145,7 +155,7 @@ export const make = Effect.gen(function* () {
   });
 
   return CheckpointStore.of({
-    isGitRepository,
+    supportsCheckpoints,
     captureCheckpoint,
     hasCheckpointRef,
     restoreCheckpoint,