diff --git a/packages/opencode/src/cli/cmd/auth.ts b/packages/opencode/src/cli/cmd/auth.ts
index 658329fb6ef..eb949ec1c1b 100644
--- a/packages/opencode/src/cli/cmd/auth.ts
+++ b/packages/opencode/src/cli/cmd/auth.ts
@@ -274,8 +274,14 @@ export const AuthLoginCommand = cmd({
           "github-copilot": 2,
           openai: 3,
           google: 4,
-          openrouter: 5,
-          vercel: 6,
+          "google-vertex": 5,
+          "google-vertex-anthropic": 6,
+          openrouter: 7,
+          vercel: 8,
+        }
+        const displayNames: Record<string, string> = {
+          "google-vertex": "Google Vertex AI",
+          "google-vertex-anthropic": "Google Vertex AI (Anthropic)",
         }
         let provider = await prompts.autocomplete({
           message: "Select provider",
@@ -289,11 +295,13 @@ export const AuthLoginCommand = cmd({
                 (x) => x.name ?? x.id,
               ),
               map((x) => ({
-                label: x.name,
+                label: displayNames[x.id] ?? x.name,
                 value: x.id,
                 hint: {
                   opencode: "recommended",
                   anthropic: "Claude Max or API key",
+                  "google-vertex": "Service Account",
+                  "google-vertex-anthropic": "Service Account",
                 }[x.id],
               })),
             ),
@@ -349,6 +357,52 @@ export const AuthLoginCommand = cmd({
           prompts.log.info("You can create an api key at https://vercel.link/ai-gateway-token")
         }
 
+        if (provider === "google-vertex" || provider === "google-vertex-anthropic") {
+          prompts.log.info("Paste your service account JSON below.")
+          prompts.log.info("Download from https://console.cloud.google.com/iam-admin/serviceaccounts")
+
+          const serviceAccountJson = await prompts.text({
+            message: "Service Account JSON",
+            placeholder: '{"type": "service_account", ...}',
+            validate: (x) => {
+              if (!x) return "Required"
+              try {
+                const json = JSON.parse(x)
+                if (json.type !== "service_account") return "Invalid: 'type' must be 'service_account'"
+                if (!json.client_email) return "Invalid: missing 'client_email' field"
+                if (!json.private_key) return "Invalid: missing 'private_key' field"
+                if (!json.project_id) return "Invalid: missing 'project_id' field"
+                return undefined
+              } catch (e) {
+                return `Invalid JSON: ${e instanceof Error ? e.message : "parse error"}`
+              }
+            },
+          })
+          if (prompts.isCancel(serviceAccountJson)) throw new UI.CancelledError()
+
+          const json = JSON.parse(serviceAccountJson)
+
+          const defaultLocation = provider === "google-vertex-anthropic" ? "global" : "us-east5"
+          const location = await prompts.text({
+            message: `Location (default: ${defaultLocation})`,
+            placeholder: defaultLocation,
+          })
+          if (prompts.isCancel(location)) throw new UI.CancelledError()
+
+          await Auth.set(provider, {
+            type: "api",
+            key: JSON.stringify({
+              client_email: json.client_email,
+              private_key: json.private_key,
+              project_id: json.project_id,
+              location: location || defaultLocation,
+            }),
+          })
+
+          prompts.outro("Done")
+          return
+        }
+
         const key = await prompts.password({
           message: "Enter your API key",
           validate: (x) => (x && x.length > 0 ? undefined : "Required"),
diff --git a/packages/opencode/src/cli/cmd/tui/component/dialog-model.tsx b/packages/opencode/src/cli/cmd/tui/component/dialog-model.tsx
index bc90dbb5c6e..3688a5f3832 100644
--- a/packages/opencode/src/cli/cmd/tui/component/dialog-model.tsx
+++ b/packages/opencode/src/cli/cmd/tui/component/dialog-model.tsx
@@ -8,6 +8,15 @@ import { createDialogProviderOptions, DialogProvider } from "./dialog-provider"
 import { Keybind } from "@/util/keybind"
 import * as fuzzysort from "fuzzysort"
 
+const PROVIDER_DISPLAY_NAMES: Record<string, string> = {
+  "google-vertex": "Google Vertex AI",
+  "google-vertex-anthropic": "Google Vertex AI (Anthropic)",
+}
+
+function getProviderDisplayName(provider: { id: string; name: string }): string {
+  return PROVIDER_DISPLAY_NAMES[provider.id] ?? provider.name
+}
+
 export function useConnected() {
   const sync = useSync()
   return createMemo(() =>
@@ -55,7 +64,7 @@ export function DialogModel(props: { providerID?: string }) {
             modelID: model.id,
           },
           title: model.name ?? item.modelID,
-          description: provider.name,
+          description: getProviderDisplayName(provider),
           category: "Favorites",
           disabled: provider.id === "opencode" && model.id.includes("-nano"),
           footer: model.cost?.input === 0 && provider.id === "opencode" ? "Free" : undefined,
@@ -86,7 +95,7 @@ export function DialogModel(props: { providerID?: string }) {
             modelID: model.id,
           },
           title: model.name ?? item.modelID,
-          description: provider.name,
+          description: getProviderDisplayName(provider),
           category: "Recent",
           disabled: provider.id === "opencode" && model.id.includes("-nano"),
           footer: model.cost?.input === 0 && provider.id === "opencode" ? "Free" : undefined,
@@ -108,7 +117,7 @@ export function DialogModel(props: { providerID?: string }) {
       sync.data.provider,
       sortBy(
         (provider) => provider.id !== "opencode",
-        (provider) => provider.name,
+        (provider) => getProviderDisplayName(provider),
       ),
       flatMap((provider) =>
         pipe(
@@ -129,7 +138,7 @@ export function DialogModel(props: { providerID?: string }) {
               )
                 ? "(Favorite)"
                 : undefined,
-              category: connected() ? provider.name : undefined,
+              category: connected() ? getProviderDisplayName(provider) : undefined,
               disabled: provider.id === "opencode" && model.includes("-nano"),
               footer: info.cost?.input === 0 && provider.id === "opencode" ? "Free" : undefined,
               onSelect() {
diff --git a/packages/opencode/src/cli/cmd/tui/component/dialog-provider.tsx b/packages/opencode/src/cli/cmd/tui/component/dialog-provider.tsx
index 5cc114f92f0..5dfaa1c25a9 100644
--- a/packages/opencode/src/cli/cmd/tui/component/dialog-provider.tsx
+++ b/packages/opencode/src/cli/cmd/tui/component/dialog-provider.tsx
@@ -16,7 +16,14 @@ const PROVIDER_PRIORITY: Record<string, number> = {
   "github-copilot": 2,
   openai: 3,
   google: 4,
-  openrouter: 5,
+  "google-vertex": 5,
+  "google-vertex-anthropic": 6,
+  openrouter: 7,
+}
+
+const PROVIDER_DISPLAY_NAMES: Record<string, string> = {
+  "google-vertex": "Google Vertex AI",
+  "google-vertex-anthropic": "Google Vertex AI (Anthropic)",
 }
 
 export function createDialogProviderOptions() {
@@ -28,11 +35,13 @@ export function createDialogProviderOptions() {
       sync.data.provider_next.all,
       sortBy((x) => PROVIDER_PRIORITY[x.id] ?? 99),
       map((provider) => ({
-        title: provider.name,
+        title: PROVIDER_DISPLAY_NAMES[provider.id] ?? provider.name,
         value: provider.id,
         description: {
           opencode: "(Recommended)",
           anthropic: "(Claude Max or API key)",
+          "google-vertex": "(Service Account)",
+          "google-vertex-anthropic": "(Service Account)",
         }[provider.id],
         category: provider.id in PROVIDER_PRIORITY ? "Popular" : "Other",
         async onSelect() {
@@ -79,6 +88,10 @@ export function createDialogProviderOptions() {
             }
           }
           if (method.type === "api") {
+            // Use ServiceAccountMethod for Vertex AI providers
+            if (provider.id === "google-vertex" || provider.id === "google-vertex-anthropic") {
+              return dialog.replace(() => <ServiceAccountMethod providerID={provider.id} />)
+            }
             return dialog.replace(() => <ApiMethod providerID={provider.id} title={method.label} />)
           }
         },
@@ -222,3 +235,164 @@ function ApiMethod(props: ApiMethodProps) {
     />
   )
 }
+
+interface ServiceAccountMethodProps {
+  providerID: string
+}
+function ServiceAccountMethod(props: ServiceAccountMethodProps) {
+  const dialog = useDialog()
+
+  onMount(() => {
+    dialog.setSize("large")
+  })
+
+  return <ServiceAccountPasteInput providerID={props.providerID} />
+}
+
+function ServiceAccountPasteInput(props: { providerID: string }) {
+  const dialog = useDialog()
+  const { theme } = useTheme()
+  const [error, setError] = createSignal("")
+  let textareaRef: any
+
+  const providerDisplayName = () =>
+    props.providerID === "google-vertex-anthropic" ? "Google Vertex AI (Anthropic)" : "Google Vertex AI"
+
+  const validateJson = (content: string): { valid: boolean; json?: any; error?: string } => {
+    try {
+      const json = JSON.parse(content)
+      if (json.type !== "service_account") {
+        return { valid: false, error: "Invalid: 'type' must be 'service_account'" }
+      }
+      if (!json.client_email) {
+        return { valid: false, error: "Invalid: missing 'client_email' field" }
+      }
+      if (!json.private_key) {
+        return { valid: false, error: "Invalid: missing 'private_key' field" }
+      }
+      if (!json.project_id) {
+        return { valid: false, error: "Invalid: missing 'project_id' field" }
+      }
+      return { valid: true, json }
+    } catch (e) {
+      return { valid: false, error: `Invalid JSON: ${e instanceof Error ? e.message : "parse error"}` }
+    }
+  }
+
+  const handleSubmit = () => {
+    const content = textareaRef?.plainText || ""
+    setError("")
+
+    if (!content || !content.trim()) {
+      setError("Required - paste your service account JSON")
+      return
+    }
+
+    const result = validateJson(content)
+    if (!result.valid) {
+      setError(result.error!)
+      return
+    }
+
+    dialog.replace(() => (
+      <ServiceAccountLocationInput
+        providerID={props.providerID}
+        serviceAccountJson={content}
+      />
+    ))
+  }
+
+  return (
+    <box gap={1} paddingBottom={1}>
+      <box paddingLeft={4} paddingRight={4}>
+        <box flexDirection="row" justifyContent="space-between">
+          <text fg={theme.text} attributes={TextAttributes.BOLD}>
+            {providerDisplayName()}
+          </text>
+          <text fg={theme.textMuted}>esc</text>
+        </box>
+        <box paddingTop={1}>
+          <text fg={theme.textMuted}>Paste your service account JSON below and press Ctrl+S to submit.</text>
+          <text fg={theme.text}>
+            Download from{" "}
+            <span style={{ fg: theme.primary }}>https://console.cloud.google.com/iam-admin/serviceaccounts</span>
+          </text>
+        </box>
+      </box>
+      <box paddingLeft={4} paddingRight={4} paddingTop={1}>
+        <textarea
+          ref={(r: any) => {
+            textareaRef = r
+            setTimeout(() => r.focus(), 1)
+          }}
+          height={15}
+          placeholder='{"type": "service_account", ...}'
+          backgroundColor={theme.backgroundElement}
+          cursorColor={theme.primary}
+          keyBindings={[{ name: "return", action: "submit" }]}
+          onSubmit={handleSubmit}
+        />
+      </box>
+      <box paddingLeft={4} paddingRight={4}>
+        <text fg={theme.textMuted}>Paste JSON and press Enter to submit</text>
+        <Show when={error()}>
+          <text fg={theme.error}>{error()}</text>
+        </Show>
+      </box>
+    </box>
+  )
+}
+
+function ServiceAccountLocationInput(props: { providerID: string; serviceAccountJson: string }) {
+  const dialog = useDialog()
+  const sdk = useSDK()
+  const sync = useSync()
+  const { theme } = useTheme()
+  const [error, setError] = createSignal("")
+
+  const defaultLocation = () => (props.providerID === "google-vertex-anthropic" ? "global" : "us-east5")
+
+  const handleLocationSubmit = async (location: string) => {
+    try {
+      const json = JSON.parse(props.serviceAccountJson)
+      const finalLocation = location || defaultLocation()
+
+      sdk.client.auth.set({
+        providerID: props.providerID,
+        auth: {
+          type: "api",
+          key: JSON.stringify({
+            client_email: json.client_email,
+            private_key: json.private_key,
+            project_id: json.project_id,
+            location: finalLocation,
+          }),
+        },
+      })
+      await sdk.client.instance.dispose()
+      await sync.bootstrap()
+      dialog.replace(() => <DialogModel providerID={props.providerID} />)
+    } catch (e) {
+      setError(`Failed to save credentials: ${e instanceof Error ? e.message : "unknown error"}`)
+    }
+  }
+
+  return (
+    <DialogPrompt
+      title="Location"
+      placeholder={defaultLocation()}
+      description={() => (
+        <box gap={1}>
+          <text fg={theme.textMuted}>Enter the Vertex AI location (region).</text>
+          <text fg={theme.text}>
+            Press enter to use default: <span style={{ fg: theme.primary }}>{defaultLocation()}</span>
+          </text>
+          <Show when={error()}>
+            <text fg={theme.error}>{error()}</text>
+          </Show>
+        </box>
+      )}
+      onConfirm={handleLocationSubmit}
+    />
+  )
+}
diff --git a/packages/opencode/src/cli/cmd/tui/context/local.tsx b/packages/opencode/src/cli/cmd/tui/context/local.tsx
index 55c04621ef3..248fe41f644 100644
--- a/packages/opencode/src/cli/cmd/tui/context/local.tsx
+++ b/packages/opencode/src/cli/cmd/tui/context/local.tsx
@@ -213,6 +213,10 @@ export const { use: useLocal, provider: LocalProvider } = createSimpleContext({
           return modelStore.favorite
         },
         parsed: createMemo(() => {
+          const PROVIDER_DISPLAY_NAMES: Record<string, string> = {
+            "google-vertex": "Google Vertex AI",
+            "google-vertex-anthropic": "Google Vertex AI (Anthropic)",
+          }
           const value = currentModel()
           if (!value) {
             return {
@@ -223,7 +227,7 @@ export const { use: useLocal, provider: LocalProvider } = createSimpleContext({
           const provider = sync.data.provider.find((x) => x.id === value.providerID)
           const info = provider?.models[value.modelID]
           return {
-            provider: provider?.name ?? value.providerID,
+            provider: PROVIDER_DISPLAY_NAMES[value.providerID] ?? provider?.name ?? value.providerID,
             model: info?.name ?? value.modelID,
           }
         }),
diff --git a/packages/opencode/src/provider/provider.ts b/packages/opencode/src/provider/provider.ts
index 62bc5beaa00..e068408a581 100644
--- a/packages/opencode/src/provider/provider.ts
+++ b/packages/opencode/src/provider/provider.ts
@@ -66,6 +66,7 @@ export namespace Provider {
     autoload: boolean
     getModel?: CustomModelLoader
     options?: Record<string, any>
+    key?: string
   }>
 
   const CUSTOM_LOADERS: Record<string, CustomLoader> = {
@@ -287,13 +288,48 @@ export namespace Provider {
       }
     },
     "google-vertex": async () => {
+      // Check for stored auth credentials first (service account JSON)
+      const auth = await Auth.get("google-vertex")
+      if (auth?.type === "api") {
+        try {
+          const creds = JSON.parse(auth.key)
+          if (creds.client_email && creds.private_key && creds.project_id) {
+            return {
+              autoload: true,
+              // Set key to undefined to prevent it from being used as apiKey
+              key: undefined,
+              options: {
+                // Explicitly set apiKey to null to prevent fallback to provider.key
+                apiKey: null,
+                project: creds.project_id,
+                location: creds.location || "us-east5",
+                googleAuthOptions: {
+                  credentials: {
+                    client_email: creds.client_email,
+                    private_key: creds.private_key,
+                  },
+                },
+              },
+              async getModel(sdk: any, modelID: string) {
+                const id = String(modelID).trim()
+                return sdk.languageModel(id)
+              },
+            }
+          }
+        } catch {
+          // Fall through to env var check
+        }
+      }
+      // Fall back to environment variables (uses ADC or GOOGLE_APPLICATION_CREDENTIALS)
       const project = Env.get("GOOGLE_CLOUD_PROJECT") ?? Env.get("GCP_PROJECT") ?? Env.get("GCLOUD_PROJECT")
       const location = Env.get("GOOGLE_CLOUD_LOCATION") ?? Env.get("VERTEX_LOCATION") ?? "us-east5"
       const autoload = Boolean(project)
       if (!autoload) return { autoload: false }
       return {
         autoload: true,
+        key: undefined,
         options: {
+          apiKey: null,
           project,
           location,
         },
@@ -304,13 +340,48 @@ export namespace Provider {
       }
     },
     "google-vertex-anthropic": async () => {
+      // Check for stored auth credentials first (service account JSON)
+      const auth = await Auth.get("google-vertex-anthropic")
+      if (auth?.type === "api") {
+        try {
+          const creds = JSON.parse(auth.key)
+          if (creds.client_email && creds.private_key && creds.project_id) {
+            return {
+              autoload: true,
+              // Set key to undefined to prevent it from being used as apiKey
+              key: undefined,
+              options: {
+                // Explicitly set apiKey to null to prevent fallback to provider.key
+                apiKey: null,
+                project: creds.project_id,
+                location: creds.location || "global",
+                googleAuthOptions: {
+                  credentials: {
+                    client_email: creds.client_email,
+                    private_key: creds.private_key,
+                  },
+                },
+              },
+              async getModel(sdk: any, modelID: string) {
+                const id = String(modelID).trim()
+                return sdk.languageModel(id)
+              },
+            }
+          }
+        } catch {
+          // Fall through to env var check
+        }
+      }
+      // Fall back to environment variables (uses ADC or GOOGLE_APPLICATION_CREDENTIALS)
       const project = Env.get("GOOGLE_CLOUD_PROJECT") ?? Env.get("GCP_PROJECT") ?? Env.get("GCLOUD_PROJECT")
       const location = Env.get("GOOGLE_CLOUD_LOCATION") ?? Env.get("VERTEX_LOCATION") ?? "global"
       const autoload = Boolean(project)
       if (!autoload) return { autoload: false }
       return {
         autoload: true,
+        key: undefined,
         options: {
+          apiKey: null,
           project,
           location,
         },
@@ -764,6 +835,9 @@ export namespace Provider {
         mergeProvider(providerID, {
           source: "custom",
           options: result.options,
+          // Pass key from custom loader if explicitly set (e.g., undefined for google-vertex)
+          // to override any key previously set from Auth storage
+          ...(result.key !== undefined ? { key: result.key } : "key" in result ? { key: undefined } : {}),
         })
       }
     }
diff --git a/packages/opencode/test/provider/provider.test.ts b/packages/opencode/test/provider/provider.test.ts
index c6c6924f01f..3225a387384 100644
--- a/packages/opencode/test/provider/provider.test.ts
+++ b/packages/opencode/test/provider/provider.test.ts
@@ -4,6 +4,7 @@ import { tmpdir } from "../fixture/fixture"
 import { Instance } from "../../src/project/instance"
 import { Provider } from "../../src/provider/provider"
 import { Env } from "../../src/env"
+import { Auth } from "../../src/auth"
 
 test("provider loaded from env variable", async () => {
   await using tmp = await tmpdir({
@@ -1807,3 +1808,448 @@ test("custom model inherits api.url from models.dev provider", async () => {
     },
   })
 })
+
+// Google Vertex AI Service Account Authentication Tests
+
+test("google-vertex loads from stored service account credentials", async () => {
+  await using tmp = await tmpdir({
+    init: async (dir) => {
+      await Bun.write(
+        path.join(dir, "opencode.json"),
+        JSON.stringify({
+          $schema: "https://opencode.ai/config.json",
+        }),
+      )
+    },
+  })
+  await Instance.provide({
+    directory: tmp.path,
+    init: async () => {
+      // Store service account credentials
+      await Auth.set("google-vertex", {
+        type: "api",
+        key: JSON.stringify({
+          client_email: "test@project.iam.gserviceaccount.com",
+          private_key: "-----BEGIN PRIVATE KEY-----\nMIItest\n-----END PRIVATE KEY-----\n",
+          project_id: "my-gcp-project",
+          location: "us-central1",
+        }),
+      })
+    },
+    fn: async () => {
+      const providers = await Provider.list()
+      expect(providers["google-vertex"]).toBeDefined()
+      expect(providers["google-vertex"].options.project).toBe("my-gcp-project")
+      expect(providers["google-vertex"].options.location).toBe("us-central1")
+      expect(providers["google-vertex"].options.googleAuthOptions).toBeDefined()
+      expect(providers["google-vertex"].options.googleAuthOptions.credentials.client_email).toBe(
+        "test@project.iam.gserviceaccount.com",
+      )
+      // Ensure apiKey is null (not set from service account JSON)
+      expect(providers["google-vertex"].options.apiKey).toBeNull()
+      // Ensure key is undefined (service account JSON should not be exposed as key)
+      expect(providers["google-vertex"].key).toBeUndefined()
+    },
+  })
+})
+
+test("google-vertex-anthropic loads from stored service account credentials", async () => {
+  await using tmp = await tmpdir({
+    init: async (dir) => {
+      await Bun.write(
+        path.join(dir, "opencode.json"),
+        JSON.stringify({
+          $schema: "https://opencode.ai/config.json",
+        }),
+      )
+    },
+  })
+  await Instance.provide({
+    directory: tmp.path,
+    init: async () => {
+      // Store service account credentials
+      await Auth.set("google-vertex-anthropic", {
+        type: "api",
+        key: JSON.stringify({
+          client_email: "anthropic-sa@project.iam.gserviceaccount.com",
+          private_key: "-----BEGIN PRIVATE KEY-----\nMIItest\n-----END PRIVATE KEY-----\n",
+          project_id: "my-anthropic-project",
+          location: "global",
+        }),
+      })
+    },
+    fn: async () => {
+      const providers = await Provider.list()
+      expect(providers["google-vertex-anthropic"]).toBeDefined()
+      expect(providers["google-vertex-anthropic"].options.project).toBe("my-anthropic-project")
+      expect(providers["google-vertex-anthropic"].options.location).toBe("global")
+      expect(providers["google-vertex-anthropic"].options.googleAuthOptions).toBeDefined()
+      expect(providers["google-vertex-anthropic"].options.googleAuthOptions.credentials.client_email).toBe(
+        "anthropic-sa@project.iam.gserviceaccount.com",
+      )
+      // Ensure apiKey is null (not set from service account JSON)
+      expect(providers["google-vertex-anthropic"].options.apiKey).toBeNull()
+      // Ensure key is undefined (service account JSON should not be exposed as key)
+      expect(providers["google-vertex-anthropic"].key).toBeUndefined()
+    },
+  })
+})
+
+test("google-vertex uses default location when not specified in credentials", async () => {
+  await using tmp = await tmpdir({
+    init: async (dir) => {
+      await Bun.write(
+        path.join(dir, "opencode.json"),
+        JSON.stringify({
+          $schema: "https://opencode.ai/config.json",
+        }),
+      )
+    },
+  })
+  await Instance.provide({
+    directory: tmp.path,
+    init: async () => {
+      // Store service account credentials without location
+      await Auth.set("google-vertex", {
+        type: "api",
+        key: JSON.stringify({
+          client_email: "test@project.iam.gserviceaccount.com",
+          private_key: "-----BEGIN PRIVATE KEY-----\nMIItest\n-----END PRIVATE KEY-----\n",
+          project_id: "my-gcp-project",
+          // no location specified
+        }),
+      })
+    },
+    fn: async () => {
+      const providers = await Provider.list()
+      expect(providers["google-vertex"]).toBeDefined()
+      expect(providers["google-vertex"].options.location).toBe("us-east5") // default location
+      expect(providers["google-vertex"].options.apiKey).toBeNull()
+      expect(providers["google-vertex"].key).toBeUndefined()
+    },
+  })
+})
+
+test("google-vertex-anthropic uses default location 'global' when not specified", async () => {
+  await using tmp = await tmpdir({
+    init: async (dir) => {
+      await Bun.write(
+        path.join(dir, "opencode.json"),
+        JSON.stringify({
+          $schema: "https://opencode.ai/config.json",
+        }),
+      )
+    },
+  })
+  await Instance.provide({
+    directory: tmp.path,
+    init: async () => {
+      // Store service account credentials without location
+      await Auth.set("google-vertex-anthropic", {
+        type: "api",
+        key: JSON.stringify({
+          client_email: "test@project.iam.gserviceaccount.com",
+          private_key: "-----BEGIN PRIVATE KEY-----\nMIItest\n-----END PRIVATE KEY-----\n",
+          project_id: "my-gcp-project",
+          // no location specified
+        }),
+      })
+    },
+    fn: async () => {
+      const providers = await Provider.list()
+      expect(providers["google-vertex-anthropic"]).toBeDefined()
+      expect(providers["google-vertex-anthropic"].options.location).toBe("global") // default location for anthropic
+      expect(providers["google-vertex-anthropic"].options.apiKey).toBeNull()
+      expect(providers["google-vertex-anthropic"].key).toBeUndefined()
+    },
+  })
+})
+
+test("google-vertex falls back to env vars when no stored credentials", async () => {
+  await using tmp = await tmpdir({
+    init: async (dir) => {
+      await Bun.write(
+        path.join(dir, "opencode.json"),
+        JSON.stringify({
+          $schema: "https://opencode.ai/config.json",
+        }),
+      )
+    },
+  })
+  await Instance.provide({
+    directory: tmp.path,
+    init: async () => {
+      // Remove any existing auth
+      await Auth.remove("google-vertex")
+      // Set env vars instead of stored credentials
+      Env.set("GOOGLE_CLOUD_PROJECT", "env-project")
+      Env.set("VERTEX_LOCATION", "europe-west1")
+    },
+    fn: async () => {
+      const providers = await Provider.list()
+      expect(providers["google-vertex"]).toBeDefined()
+      expect(providers["google-vertex"].options.project).toBe("env-project")
+      expect(providers["google-vertex"].options.location).toBe("europe-west1")
+      // No googleAuthOptions when using env vars
+      expect(providers["google-vertex"].options.googleAuthOptions).toBeUndefined()
+      // apiKey should still be null to prevent fallback to other API keys
+      expect(providers["google-vertex"].options.apiKey).toBeNull()
+      expect(providers["google-vertex"].key).toBeUndefined()
+    },
+  })
+})
+
+test("google-vertex not loaded when neither credentials nor env vars set", async () => {
+  await using tmp = await tmpdir({
+    init: async (dir) => {
+      await Bun.write(
+        path.join(dir, "opencode.json"),
+        JSON.stringify({
+          $schema: "https://opencode.ai/config.json",
+        }),
+      )
+    },
+  })
+  await Instance.provide({
+    directory: tmp.path,
+    init: async () => {
+      // Clean up any existing auth and env vars
+      await Auth.remove("google-vertex")
+      Env.set("GOOGLE_CLOUD_PROJECT", "")
+      Env.set("GCP_PROJECT", "")
+      Env.set("GCLOUD_PROJECT", "")
+    },
+    fn: async () => {
+      const providers = await Provider.list()
+      expect(providers["google-vertex"]).toBeUndefined()
+    },
+  })
+})
+
+test("google-vertex ignores incomplete stored credentials", async () => {
+  await using tmp = await tmpdir({
+    init: async (dir) => {
+      await Bun.write(
+        path.join(dir, "opencode.json"),
+        JSON.stringify({
+          $schema: "https://opencode.ai/config.json",
+        }),
+      )
+    },
+  })
+  await Instance.provide({
+    directory: tmp.path,
+    init: async () => {
+      // Store incomplete credentials (missing private_key)
+      await Auth.set("google-vertex", {
+        type: "api",
+        key: JSON.stringify({
+          client_email: "test@project.iam.gserviceaccount.com",
+          // missing private_key
+          project_id: "my-gcp-project",
+        }),
+      })
+      // Also set env vars as fallback
+      Env.set("GOOGLE_CLOUD_PROJECT", "fallback-project")
+    },
+    fn: async () => {
+      const providers = await Provider.list()
+      expect(providers["google-vertex"]).toBeDefined()
+      // Should fall back to env vars
+      expect(providers["google-vertex"].options.project).toBe("fallback-project")
+      expect(providers["google-vertex"].options.googleAuthOptions).toBeUndefined()
+    },
+  })
+})
+
+test("google-vertex ignores invalid JSON in stored credentials", async () => {
+  await using tmp = await tmpdir({
+    init: async (dir) => {
+      await Bun.write(
+        path.join(dir, "opencode.json"),
+        JSON.stringify({
+          $schema: "https://opencode.ai/config.json",
+        }),
+      )
+    },
+  })
+  await Instance.provide({
+    directory: tmp.path,
+    init: async () => {
+      // Store invalid JSON
+      await Auth.set("google-vertex", {
+        type: "api",
+        key: "not valid json",
+      })
+      // Also set env vars as fallback
+      Env.set("GOOGLE_CLOUD_PROJECT", "fallback-project")
+    },
+    fn: async () => {
+      const providers = await Provider.list()
+      expect(providers["google-vertex"]).toBeDefined()
+      // Should fall back to env vars
+      expect(providers["google-vertex"].options.project).toBe("fallback-project")
+    },
+  })
+})
+
+test("google-vertex stored credentials take priority over env vars", async () => {
+  await using tmp = await tmpdir({
+    init: async (dir) => {
+      await Bun.write(
+        path.join(dir, "opencode.json"),
+        JSON.stringify({
+          $schema: "https://opencode.ai/config.json",
+        }),
+      )
+    },
+  })
+  await Instance.provide({
+    directory: tmp.path,
+    init: async () => {
+      // Store service account credentials
+      await Auth.set("google-vertex", {
+        type: "api",
+        key: JSON.stringify({
+          client_email: "stored@project.iam.gserviceaccount.com",
+          private_key: "-----BEGIN PRIVATE KEY-----\nMIItest\n-----END PRIVATE KEY-----\n",
+          project_id: "stored-project",
+          location: "stored-location",
+        }),
+      })
+      // Also set env vars
+      Env.set("GOOGLE_CLOUD_PROJECT", "env-project")
+      Env.set("VERTEX_LOCATION", "env-location")
+    },
+    fn: async () => {
+      const providers = await Provider.list()
+      expect(providers["google-vertex"]).toBeDefined()
+      // Stored credentials should take priority
+      expect(providers["google-vertex"].options.project).toBe("stored-project")
+      expect(providers["google-vertex"].options.location).toBe("stored-location")
+      expect(providers["google-vertex"].options.googleAuthOptions).toBeDefined()
+      // Ensure apiKey is null even when env vars are set
+      expect(providers["google-vertex"].options.apiKey).toBeNull()
+      expect(providers["google-vertex"].key).toBeUndefined()
+    },
+  })
+})
+
+test("google-vertex and google (Gemini) providers are completely separate", async () => {
+  await using tmp = await tmpdir({
+    init: async (dir) => {
+      await Bun.write(
+        path.join(dir, "opencode.json"),
+        JSON.stringify({
+          $schema: "https://opencode.ai/config.json",
+        }),
+      )
+    },
+  })
+  await Instance.provide({
+    directory: tmp.path,
+    init: async () => {
+      // Set up google (Gemini) with API key
+      Env.set("GOOGLE_GENERATIVE_AI_API_KEY", "my-gemini-api-key")
+
+      // Set up google-vertex with service account credentials
+      await Auth.set("google-vertex", {
+        type: "api",
+        key: JSON.stringify({
+          client_email: "vertex@project.iam.gserviceaccount.com",
+          private_key: "-----BEGIN PRIVATE KEY-----\nMIItest\n-----END PRIVATE KEY-----\n",
+          project_id: "vertex-project",
+          location: "us-central1",
+        }),
+      })
+    },
+    fn: async () => {
+      const providers = await Provider.list()
+
+      // Both providers should be loaded
+      expect(providers["google"]).toBeDefined()
+      expect(providers["google-vertex"]).toBeDefined()
+
+      // google (Gemini) is loaded from env var (google has multiple env vars so key isn't stored directly)
+      expect(providers["google"].source).toBe("env")
+
+      // google-vertex should NOT use the Gemini API key
+      expect(providers["google-vertex"].key).toBeUndefined()
+      expect(providers["google-vertex"].options.apiKey).toBeNull()
+
+      // google-vertex should use service account auth
+      expect(providers["google-vertex"].options.project).toBe("vertex-project")
+      expect(providers["google-vertex"].options.googleAuthOptions).toBeDefined()
+      expect(providers["google-vertex"].options.googleAuthOptions.credentials.client_email).toBe(
+        "vertex@project.iam.gserviceaccount.com",
+      )
+    },
+  })
+})
+
+test("google-vertex-anthropic is separate from google and google-vertex", async () => {
+  await using tmp = await tmpdir({
+    init: async (dir) => {
+      await Bun.write(
+        path.join(dir, "opencode.json"),
+        JSON.stringify({
+          $schema: "https://opencode.ai/config.json",
+        }),
+      )
+    },
+  })
+  await Instance.provide({
+    directory: tmp.path,
+    init: async () => {
+      // Set up all three providers
+      Env.set("GOOGLE_GENERATIVE_AI_API_KEY", "gemini-key")
+
+      await Auth.set("google-vertex", {
+        type: "api",
+        key: JSON.stringify({
+          client_email: "vertex@project.iam.gserviceaccount.com",
+          private_key: "-----BEGIN PRIVATE KEY-----\nMIItest\n-----END PRIVATE KEY-----\n",
+          project_id: "vertex-project",
+          location: "us-central1",
+        }),
+      })
+
+      await Auth.set("google-vertex-anthropic", {
+        type: "api",
+        key: JSON.stringify({
+          client_email: "anthropic@project.iam.gserviceaccount.com",
+          private_key: "-----BEGIN PRIVATE KEY-----\nMIItest2\n-----END PRIVATE KEY-----\n",
+          project_id: "anthropic-project",
+          location: "global",
+        }),
+      })
+    },
+    fn: async () => {
+      const providers = await Provider.list()
+
+      // All three should be separate
+      expect(providers["google"]).toBeDefined()
+      expect(providers["google-vertex"]).toBeDefined()
+      expect(providers["google-vertex-anthropic"]).toBeDefined()
+
+      // google is loaded from env var (google has multiple env vars so key isn't stored directly)
+      expect(providers["google"].source).toBe("env")
+
+      // google-vertex uses its own service account
+      expect(providers["google-vertex"].options.project).toBe("vertex-project")
+      expect(providers["google-vertex"].options.googleAuthOptions.credentials.client_email).toBe(
+        "vertex@project.iam.gserviceaccount.com",
+      )
+      expect(providers["google-vertex"].key).toBeUndefined()
+      expect(providers["google-vertex"].options.apiKey).toBeNull()
+
+      // google-vertex-anthropic uses its own separate service account
+      expect(providers["google-vertex-anthropic"].options.project).toBe("anthropic-project")
+      expect(providers["google-vertex-anthropic"].options.googleAuthOptions.credentials.client_email).toBe(
+        "anthropic@project.iam.gserviceaccount.com",
+      )
+      expect(providers["google-vertex-anthropic"].key).toBeUndefined()
+      expect(providers["google-vertex-anthropic"].options.apiKey).toBeNull()
+    },
+  })
+})