fix+refactor(vcs): fix HEAD filter bug and effectify VcsService (#17829)

packages/opencode/test/fixture/instance.ts

@@ -0,0 +1,47 @@
+import { ConfigProvider, Layer, ManagedRuntime } from "effect"
+import { InstanceContext } from "../../src/effect/instance-context"
+import { Instance } from "../../src/project/instance"
+
+/** ConfigProvider that enables the experimental file watcher. */
+export const watcherConfigLayer = ConfigProvider.layer(
+  ConfigProvider.fromUnknown({
+    OPENCODE_EXPERIMENTAL_FILEWATCHER: "true",
+    OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER: "false",
+  }),
+)
+
+/**
+ * Boot an Instance with the given service layers and run `body` with
+ * the ManagedRuntime. Cleanup is automatic — the runtime is disposed
+ * and Instance context is torn down when `body` completes.
+ *
+ * Layers may depend on InstanceContext (provided automatically).
+ * Pass extra layers via `options.provide` (e.g. ConfigProvider.layer).
+ */
+export function withServices<S>(
+  directory: string,
+  layer: Layer.Layer<S, any, InstanceContext>,
+  body: (rt: ManagedRuntime.ManagedRuntime<S, never>) => Promise<void>,
+  options?: { provide?: Layer.Layer<never>[] },
+) {
+  return Instance.provide({
+    directory,
+    fn: async () => {
+      const ctx = Layer.sync(InstanceContext, () =>
+        InstanceContext.of({ directory: Instance.directory, project: Instance.project }),
+      )
+      let resolved: Layer.Layer<S> = Layer.fresh(layer).pipe(Layer.provide(ctx)) as any
+      if (options?.provide) {
+        for (const l of options.provide) {
+          resolved = resolved.pipe(Layer.provide(l)) as any
+        }
+      }
+      const rt = ManagedRuntime.make(resolved)
+      try {
+        await body(rt)
+      } finally {
+        await rt.dispose()
+      }
+    },
+  })
+}