effect: add RuntimeFlags service (#27181)

packages/opencode/test/effect/runtime-flags.test.ts

@@ -0,0 +1,55 @@
+import { describe, expect } from "bun:test"
+import { ConfigProvider, Effect, Layer } from "effect"
+import { RuntimeFlags } from "../../src/effect/runtime-flags"
+import { it } from "../lib/effect"
+
+const fromConfig = (input: Record<string, unknown>) =>
+  RuntimeFlags.defaultLayer.pipe(Layer.provide(ConfigProvider.layer(ConfigProvider.fromUnknown(input))))
+
+const readFlags = RuntimeFlags.Service.useSync((flags) => flags)
+
+describe("RuntimeFlags", () => {
+  it.effect("defaultLayer parses plugin flags from the active ConfigProvider", () =>
+    Effect.gen(function* () {
+      const flags = yield* readFlags.pipe(
+        Effect.provide(
+          fromConfig({
+            OPENCODE_PURE: "true",
+            OPENCODE_DISABLE_DEFAULT_PLUGINS: "true",
+          }),
+        ),
+      )
+
+      expect(flags.pure).toBe(true)
+      expect(flags.disableDefaultPlugins).toBe(true)
+    }),
+  )
+
+  it.effect("layer accepts partial test overrides and fills defaults from Config definitions", () =>
+    Effect.gen(function* () {
+      const flags = yield* readFlags.pipe(Effect.provide(RuntimeFlags.layer({ disableDefaultPlugins: true })))
+
+      expect(flags.pure).toBe(false)
+      expect(flags.disableDefaultPlugins).toBe(true)
+    }),
+  )
+
+  it.effect("layer ignores the active ConfigProvider for omitted test overrides", () =>
+    Effect.gen(function* () {
+      const flags = yield* readFlags.pipe(
+        Effect.provide(RuntimeFlags.layer()),
+        Effect.provide(
+          ConfigProvider.layer(
+            ConfigProvider.fromUnknown({
+              OPENCODE_PURE: "true",
+              OPENCODE_DISABLE_DEFAULT_PLUGINS: "true",
+            }),
+          ),
+        ),
+      )
+
+      expect(flags.pure).toBe(false)
+      expect(flags.disableDefaultPlugins).toBe(false)
+    }),
+  )
+})