fix(vertex): EU/US REP + global endpoints, and fix v@ routing fall-through to OpenRouter

CHANGELOG.md

@@ -2,6 +2,16 @@
 
 All notable changes to [Claudish](https://github.com/MadAppGang/claudish).
 
+## [Unreleased]
+
+### Bug Fixes
+
+- **vertex**: fix `v@`/`vertex@` models silently falling through to the OpenRouter default (HTTP 401). Vertex has a static `baseUrl: ""` (its endpoint is built per-region in the vertex transport), so the empty-baseUrl filter in `getRemoteProviders()` dropped it from the registry and `resolveRemoteProvider()` returned null. Keep Vertex regardless of its empty static baseUrl.
+
+### New Features
+
+- **vertex**: support EU/US data-residency multi-region (`aiplatform.<loc>.rep.googleapis.com`) and `global` endpoints via `VERTEX_LOCATION=eu|us|global`. Enables Gemini models published only on the REP endpoint, such as `gemini-3.5-flash` with EU data residency.
+
 ## [7.5.0] - 2026-06-10
 
 ### Documentation

docs/settings-reference.md

@@ -161,7 +161,7 @@ Claudish automatically loads `.env` from the current working directory at startu
 | `POE_API_KEY` | Poe (`poe@`) | | https://poe.com/ |
 | `VERTEX_API_KEY` | Vertex AI Express mode (`v@`, `vertex@`) | | https://console.cloud.google.com/vertex-ai |
 | `VERTEX_PROJECT` | Vertex AI OAuth mode — GCP project ID | `GOOGLE_CLOUD_PROJECT` | GCP Console |
-| `VERTEX_LOCATION` | Vertex AI region | `us-central1` | |
+| `VERTEX_LOCATION` | Vertex AI region. A normal region (e.g. `europe-west4`) hits `<region>-aiplatform.googleapis.com`. `eu`/`us` hit the data-residency multi-region endpoint `aiplatform.<loc>.rep.googleapis.com` (required for models published only there, e.g. `gemini-3.5-flash`). `global` hits `aiplatform.googleapis.com` (max availability, no data-residency guarantee). | `us-central1` | |
 | `GOOGLE_APPLICATION_CREDENTIALS` | Path to GCP service account JSON file (Vertex OAuth) | | GCP Console |
 | `GOOGLE_CLOUD_PROJECT` | GCP project ID (also used by Gemini Code Assist OAuth) | `GOOGLE_CLOUD_PROJECT_ID` | |
 

packages/cli/.gitignore

@@ -1 +1,5 @@
 .claudish-team-*
+
+# Build artifacts
+claudish
+*.bun-build

packages/cli/scripts/smoke/providers.ts

@@ -8,6 +8,7 @@
 
 import type { RemoteProvider } from "../../src/handlers/shared/remote-provider-types.js";
 import { getRegisteredRemoteProviders } from "../../src/providers/remote-provider-registry.js";
+import { vertexApiHost } from "../../src/auth/vertex-auth.js";
 import type { SmokeProviderConfig, WireFormat } from "./types.js";
 
 // Providers to skip in v1 smoke tests
@@ -142,7 +143,7 @@ function getApiPath(provider: RemoteProvider): string {
 function getBaseUrl(provider: RemoteProvider): string {
   if (provider.name === "vertex") {
     const location = process.env.VERTEX_LOCATION || "us-central1";
-    return `https://${location}-aiplatform.googleapis.com`;
+    return `https://${vertexApiHost(location)}`;
   }
   return provider.baseUrl;
 }

packages/cli/src/auth/vertex-auth.test.ts

@@ -0,0 +1,76 @@
+import { describe, it, expect } from "bun:test";
+import { vertexApiHost, buildVertexOAuthEndpoint } from "./vertex-auth.js";
+
+describe("vertexApiHost", () => {
+  it("uses the classic single-region host for normal regions", () => {
+    expect(vertexApiHost("europe-west4")).toBe(
+      "europe-west4-aiplatform.googleapis.com"
+    );
+    expect(vertexApiHost("us-central1")).toBe(
+      "us-central1-aiplatform.googleapis.com"
+    );
+  });
+
+  it("uses the bare global host for location=global", () => {
+    expect(vertexApiHost("global")).toBe("aiplatform.googleapis.com");
+  });
+
+  it("uses the data-residency REP host for eu/us multi-region", () => {
+    expect(vertexApiHost("eu")).toBe("aiplatform.eu.rep.googleapis.com");
+    expect(vertexApiHost("us")).toBe("aiplatform.us.rep.googleapis.com");
+  });
+});
+
+describe("buildVertexOAuthEndpoint (google)", () => {
+  const cfg = { projectId: "p", location: "eu" };
+
+  it("targets the EU REP host while keeping the locations/<loc> path", () => {
+    expect(
+      buildVertexOAuthEndpoint(cfg, "google", "gemini-3.5-flash", false)
+    ).toBe(
+      "https://aiplatform.eu.rep.googleapis.com/v1/" +
+        "projects/p/locations/eu/publishers/google/models/" +
+        "gemini-3.5-flash:generateContent"
+    );
+  });
+
+  it("appends ?alt=sse for streaming", () => {
+    expect(
+      buildVertexOAuthEndpoint(cfg, "google", "gemini-3.5-flash", true)
+    ).toBe(
+      "https://aiplatform.eu.rep.googleapis.com/v1/" +
+        "projects/p/locations/eu/publishers/google/models/" +
+        "gemini-3.5-flash:streamGenerateContent?alt=sse"
+    );
+  });
+
+  it("still builds the classic regional host for a normal region", () => {
+    expect(
+      buildVertexOAuthEndpoint(
+        { projectId: "p", location: "europe-west4" },
+        "google",
+        "gemini-2.5-pro",
+        false
+      )
+    ).toBe(
+      "https://europe-west4-aiplatform.googleapis.com/v1/" +
+        "projects/p/locations/europe-west4/publishers/google/models/" +
+        "gemini-2.5-pro:generateContent"
+    );
+  });
+
+  it("targets the bare global host for location=global", () => {
+    expect(
+      buildVertexOAuthEndpoint(
+        { projectId: "p", location: "global" },
+        "google",
+        "gemini-2.5-pro",
+        false
+      )
+    ).toBe(
+      "https://aiplatform.googleapis.com/v1/" +
+        "projects/p/locations/global/publishers/google/models/" +
+        "gemini-2.5-pro:generateContent"
+    );
+  });
+});

packages/cli/src/auth/vertex-auth.ts

@@ -231,6 +231,31 @@ export function validateVertexOAuthConfig(): string | null {
   return null;
 }
 
+/**
+ * Resolve the Vertex AI API host for a given location.
+ *
+ * Vertex exposes Gemini through three host families, each with a different
+ * shape — picking the wrong one yields a 404, so we can't always prefix with
+ * `<location>-`:
+ *   - `global`            -> aiplatform.googleapis.com            (highest
+ *                            availability, NO data-residency guarantee)
+ *   - `eu` / `us`         -> aiplatform.<loc>.rep.googleapis.com  (data-residency
+ *                            multi-region "REP" endpoints; some newer models
+ *                            such as gemini-3.5-flash are published ONLY here)
+ *   - any other region    -> <location>-aiplatform.googleapis.com (classic
+ *                            single-region endpoint, e.g. europe-west4)
+ *
+ * The `locations/<location>` path segment is unchanged in every case.
+ * See: https://docs.cloud.google.com/vertex-ai/generative-ai/docs/learn/locations
+ */
+export function vertexApiHost(location: string): string {
+  if (location === "global") return "aiplatform.googleapis.com";
+  if (location === "eu" || location === "us") {
+    return `aiplatform.${location}.rep.googleapis.com`;
+  }
+  return `${location}-aiplatform.googleapis.com`;
+}
+
 /**
  * Build Vertex AI endpoint URL for OAuth mode
  */
@@ -241,22 +266,23 @@ export function buildVertexOAuthEndpoint(
   streaming: boolean = true
 ): string {
   const method = streaming ? "streamGenerateContent" : "generateContent";
+  const host = vertexApiHost(config.location);
 
   // For Gemini models (publisher: google), use generateContent
   // For partner models (publisher: anthropic, mistral), use rawPredict
   if (publisher === "google") {
     // Add ?alt=sse for SSE streaming format
     const sseParam = streaming ? "?alt=sse" : "";
     return (
-      `https://${config.location}-aiplatform.googleapis.com/v1/` +
+      `https://${host}/v1/` +
       `projects/${config.projectId}/locations/${config.location}/` +
       `publishers/${publisher}/models/${model}:${method}${sseParam}`
     );
   } else if (publisher === "mistralai") {
     // Mistral uses regional rawPredict/streamRawPredict endpoint
     const mistralMethod = streaming ? "streamRawPredict" : "rawPredict";
     return (
-      `https://${config.location}-aiplatform.googleapis.com/v1/` +
+      `https://${host}/v1/` +
       `projects/${config.projectId}/locations/${config.location}/` +
       `publishers/mistralai/models/${model}:${mistralMethod}`
     );

packages/cli/src/providers/remote-provider-registry.test.ts

@@ -0,0 +1,29 @@
+import { describe, it, expect } from "bun:test";
+import { resolveRemoteProvider } from "./remote-provider-registry.js";
+
+describe("resolveRemoteProvider — vertex", () => {
+  // Regression: Vertex has a static baseUrl of "" (its endpoint is built
+  // per-region in the vertex transport). A baseUrl-emptiness filter in
+  // getRemoteProviders() used to drop it, so `v@`/`vertex@` resolved to null
+  // and every Vertex request silently fell through to the OpenRouter default
+  // (HTTP 401). Vertex must resolve regardless of its empty static baseUrl.
+  it("resolves v@ to the vertex provider", () => {
+    const r = resolveRemoteProvider("v@gemini-3.5-flash");
+    expect(r).not.toBeNull();
+    expect(r!.provider.name).toBe("vertex");
+    expect(r!.modelName).toBe("gemini-3.5-flash");
+  });
+
+  it("resolves vertex@ to the vertex provider", () => {
+    const r = resolveRemoteProvider("vertex@gemini-2.5-pro");
+    expect(r).not.toBeNull();
+    expect(r!.provider.name).toBe("vertex");
+    expect(r!.modelName).toBe("gemini-2.5-pro");
+  });
+
+  it("resolves the legacy v/ prefix to the vertex provider", () => {
+    const r = resolveRemoteProvider("v/gemini-3.5-flash");
+    expect(r).not.toBeNull();
+    expect(r!.provider.name).toBe("vertex");
+  });
+});

packages/cli/src/providers/remote-provider-registry.ts

@@ -49,7 +49,13 @@ const getRemoteProviders = (): RemoteProvider[] => {
         // (static baseUrl: "", populated via LITELLM_BASE_URL) aren't filtered
         // out. Without this, resolveRemoteProvider("litellm@...") returns null
         // and probe-discovery / runtime routing both fail.
-        getEffectiveBaseUrl(def) !== "" &&
+        //
+        // Vertex AI also has a static baseUrl of "" because its endpoint is
+        // constructed per-region/publisher in the vertex transport (see
+        // buildVertexOAuthEndpoint). Keep it regardless of baseUrl, otherwise
+        // resolveRemoteProvider("v@...") returns null and every Vertex request
+        // silently falls through to the OpenRouter default → HTTP 401.
+        (getEffectiveBaseUrl(def) !== "" || def.transport === "vertex") &&
         def.name !== "qwen" &&
         def.name !== "native-anthropic"
     )