refactor(webapp): move the pure streams-version resolver out of the env-bound module

The resolver was written to take its configuration rather than read `env`, but
it still lived beside the singleton that reads it, so the unit test pulled
`env.server` in transitively, which the webapp rules forbid. Same split as
nativeRealtimeClient and its instance module: the pure function has no imports
at all, and the env-bound wrapper stays where the singletons are.

Renames the test to match the function it exercises.

Author: matt-aitken

apps/webapp/app/services/realtime/realtimeStreamsVersion.ts

@@ -0,0 +1,44 @@
+/**
+ * Pure realtime-streams version resolution. Deliberately free of `env` and of
+ * any module-scope singletons so it can be tested with injected values, the
+ * same split as `nativeRealtimeClient` and `nativeRealtimeClientInstance`.
+ * The env-bound wrapper is `determineRealtimeStreamsVersion` in
+ * `v1StreamsGlobal.server.ts`.
+ */
+
+export type RealtimeStreamsVersionConfig = {
+  defaultVersion: "v1" | "v2";
+  /** A basin that will actually resolve at read/write time, or undefined if none will. */
+  basin?: string;
+  accessToken?: string;
+  skipAccessTokens: boolean;
+};
+
+/**
+ * Resolve the streams version to stamp on a run, falling back to the
+ * deployment default when the caller expresses no preference.
+ *
+ * v2 is only ever returned when S2 can actually serve it. A run stamped v2 on a
+ * deployment without S2 is unusable: `getRealtimeStreamInstance` throws for the
+ * life of the run, and no read or write against its streams can succeed. v1 is
+ * a working backend, so an unsatisfiable v2 degrades to it.
+ *
+ * The basin must be one that will actually resolve later. Enabling per-org
+ * basins is not enough on its own: provisioning is out of band, so an
+ * unprovisioned organization has no basin and a global setting may not exist
+ * to fall back to.
+ */
+export function resolveRealtimeStreamsVersion(
+  streamVersion: string | undefined,
+  config: RealtimeStreamsVersionConfig
+): "v1" | "v2" {
+  const requested = streamVersion ?? config.defaultVersion;
+
+  if (requested !== "v2") {
+    return "v1";
+  }
+
+  const hasCredentials = Boolean(config.accessToken) || config.skipAccessTokens;
+
+  return hasCredentials && Boolean(config.basin) ? "v2" : "v1";
+}

apps/webapp/app/services/realtime/v1StreamsGlobal.server.ts

@@ -10,6 +10,10 @@ import { singleton } from "~/utils/singleton";
 import type { AuthenticatedEnvironment } from "../apiAuth.server";
 import { RedisRealtimeStreams } from "./redisRealtimeStreams.server";
 import { S2RealtimeStreams } from "./s2realtimeStreams.server";
+import {
+  resolveRealtimeStreamsVersion,
+  type RealtimeStreamsVersionConfig,
+} from "./realtimeStreamsVersion";
 import type { StreamIngestor, StreamResponder } from "./types";
 
 function initializeRedisRealtimeStreams() {
@@ -96,42 +100,7 @@ function streamPrefixFor(environment: AuthenticatedEnvironment, basin: string):
   return segments.join("/");
 }
 
-export type RealtimeStreamsVersionConfig = {
-  defaultVersion: "v1" | "v2";
-  /** A basin that will actually resolve at read/write time, or undefined if none will. */
-  basin?: string;
-  accessToken?: string;
-  skipAccessTokens: boolean;
-};
-
-/**
- * Resolve the streams version to stamp on a run, falling back to the
- * deployment default when the caller expresses no preference.
- *
- * v2 is only ever returned when S2 can actually serve it. A run stamped v2 on a
- * deployment without S2 is unusable: `getRealtimeStreamInstance` throws for the
- * life of the run, and no read or write against its streams can succeed. v1 is
- * a working backend, so an unsatisfiable v2 degrades to it.
- *
- * The basin must be one that will actually resolve later. Enabling per-org
- * basins is not enough on its own: provisioning is out of band, so an
- * unprovisioned organization has no basin and a global setting may not exist
- * to fall back to.
- */
-export function resolveRealtimeStreamsVersion(
-  streamVersion: string | undefined,
-  config: RealtimeStreamsVersionConfig
-): "v1" | "v2" {
-  const requested = streamVersion ?? config.defaultVersion;
-
-  if (requested !== "v2") {
-    return "v1";
-  }
-
-  const hasCredentials = Boolean(config.accessToken) || config.skipAccessTokens;
-
-  return hasCredentials && Boolean(config.basin) ? "v2" : "v1";
-}
+export type { RealtimeStreamsVersionConfig };
 
 /**
  * Pass `organizationBasinName` wherever the caller has it. It mirrors the

…/determineRealtimeStreamsVersion.test.ts …bapp/test/realtimeStreamsVersion.test.tsapps/webapp/test/determineRealtimeStreamsVersion.test.ts renamed to apps/webapp/test/realtimeStreamsVersion.test.ts apps/webapp/test/determineRealtimeStreamsVersion.test.ts renamed to apps/webapp/test/realtimeStreamsVersion.test.ts

@@ -2,7 +2,7 @@ import { describe, expect, it } from "vitest";
 import {
   resolveRealtimeStreamsVersion,
   type RealtimeStreamsVersionConfig,
-} from "~/services/realtime/v1StreamsGlobal.server";
+} from "~/services/realtime/realtimeStreamsVersion";
 
 const NO_S2: RealtimeStreamsVersionConfig = {
   defaultVersion: "v1",