diff --git a/.gitignore b/.gitignore
index ce3d19e778c6..1ff816a4e833 100644
--- a/.gitignore
+++ b/.gitignore
@@ -14,6 +14,7 @@ ts-dist
 .turbo
 **/.serena
 .serena/
+.sisyphus/
 /result
 refs
 Session.vim
diff --git a/packages/opencode/src/cli/cmd/acp.ts b/packages/opencode/src/cli/cmd/acp.ts
index 99a9a81ab9cd..a6dca88d53d1 100644
--- a/packages/opencode/src/cli/cmd/acp.ts
+++ b/packages/opencode/src/cli/cmd/acp.ts
@@ -1,4 +1,5 @@
 import { Log } from "@/util/log"
+
 import { bootstrap } from "../bootstrap"
 import { cmd } from "./cmd"
 import { AgentSideConnection, ndJsonStream } from "@agentclientprotocol/sdk"
@@ -20,7 +21,7 @@ export const AcpCommand = cmd({
     })
   },
   handler: async (args) => {
-    process.env.OPENCODE_CLIENT = "acp"
+    process.env["OPENCODE_CLIENT"] = "acp"
     await bootstrap(process.cwd(), async () => {
       const opts = await resolveNetworkOptions(args)
       const server = Server.listen(opts)
diff --git a/packages/opencode/src/cli/cmd/auth.ts b/packages/opencode/src/cli/cmd/auth.ts
index e050a0abf803..cf4a522b2653 100644
--- a/packages/opencode/src/cli/cmd/auth.ts
+++ b/packages/opencode/src/cli/cmd/auth.ts
@@ -1,4 +1,5 @@
 import { Auth } from "../../auth"
+
 import { cmd } from "./cmd"
 import * as prompts from "@clack/prompts"
 import { UI } from "../ui"
diff --git a/packages/opencode/src/cli/cmd/github.ts b/packages/opencode/src/cli/cmd/github.ts
index 7f9a03d948a0..3eb67e03100d 100644
--- a/packages/opencode/src/cli/cmd/github.ts
+++ b/packages/opencode/src/cli/cmd/github.ts
@@ -16,6 +16,7 @@ import type {
   PullRequestEvent,
 } from "@octokit/webhooks-types"
 import { UI } from "../ui"
+
 import { cmd } from "./cmd"
 import { ModelsDev } from "../../provider/models"
 import { Instance } from "@/project/instance"
diff --git a/packages/opencode/src/cli/cmd/tui/attach.ts b/packages/opencode/src/cli/cmd/tui/attach.ts
index a2559cfce679..81613dc2b48e 100644
--- a/packages/opencode/src/cli/cmd/tui/attach.ts
+++ b/packages/opencode/src/cli/cmd/tui/attach.ts
@@ -1,6 +1,7 @@
 import { cmd } from "../cmd"
 import { UI } from "@/cli/ui"
 import { tui } from "./app"
+
 import { win32DisableProcessedInput, win32InstallCtrlCGuard } from "./win32"
 
 export const AttachCommand = cmd({
@@ -58,7 +59,7 @@ export const AttachCommand = cmd({
         }
       })()
       const headers = (() => {
-        const password = args.password ?? process.env.OPENCODE_SERVER_PASSWORD
+        const password = args.password ?? process.env["OPENCODE_SERVER_PASSWORD"]
         if (!password) return undefined
         const auth = `Basic ${Buffer.from(`opencode:${password}`).toString("base64")}`
         return { Authorization: auth }
diff --git a/packages/opencode/src/cli/cmd/tui/thread.ts b/packages/opencode/src/cli/cmd/tui/thread.ts
index 9eb296032732..fc6ff90d350d 100644
--- a/packages/opencode/src/cli/cmd/tui/thread.ts
+++ b/packages/opencode/src/cli/cmd/tui/thread.ts
@@ -9,6 +9,7 @@ import { Log } from "@/util/log"
 import { withNetworkOptions, resolveNetworkOptions } from "@/cli/network"
 import type { Event } from "@opencode-ai/sdk/v2"
 import type { EventSource } from "./context/sdk"
+
 import { win32DisableProcessedInput, win32InstallCtrlCGuard } from "./win32"
 
 declare global {
@@ -93,7 +94,7 @@ export const TuiThreadCommand = cmd({
       }
 
       // Resolve relative paths against PWD to preserve behavior when using --cwd flag
-      const baseCwd = process.env.PWD ?? process.cwd()
+      const baseCwd = process.env["PWD"] ?? process.cwd()
       const cwd = args.project ? path.resolve(baseCwd, args.project) : process.cwd()
       const localWorker = new URL("./worker.ts", import.meta.url)
       const distWorker = new URL("./cli/cmd/tui/worker.js", import.meta.url)
diff --git a/packages/opencode/src/cli/cmd/uninstall.ts b/packages/opencode/src/cli/cmd/uninstall.ts
index 704d3572bbb4..38604c9a65c3 100644
--- a/packages/opencode/src/cli/cmd/uninstall.ts
+++ b/packages/opencode/src/cli/cmd/uninstall.ts
@@ -3,6 +3,7 @@ import { UI } from "../ui"
 import * as prompts from "@clack/prompts"
 import { Installation } from "../../installation"
 import { Global } from "../../global"
+
 import { $ } from "bun"
 import fs from "fs/promises"
 import path from "path"
@@ -235,9 +236,9 @@ async function executeUninstall(method: Installation.Method, targets: RemovalTar
 }
 
 async function getShellConfigFile(): Promise<string | null> {
-  const shell = path.basename(process.env.SHELL || "bash")
+  const shell = path.basename(process.env["SHELL"] || "bash")
   const home = os.homedir()
-  const xdgConfig = process.env.XDG_CONFIG_HOME || path.join(home, ".config")
+  const xdgConfig = process.env["XDG_CONFIG_HOME"] || path.join(home, ".config")
 
   const configFiles: Record<string, string[]> = {
     fish: [path.join(xdgConfig, "fish", "config.fish")],
diff --git a/packages/opencode/src/config/config.ts b/packages/opencode/src/config/config.ts
index 261731b8b0a4..11610bdc53b4 100644
--- a/packages/opencode/src/config/config.ts
+++ b/packages/opencode/src/config/config.ts
@@ -3,6 +3,7 @@ import path from "path"
 import { pathToFileURL } from "url"
 import os from "os"
 import z from "zod"
+
 import { Filesystem } from "../util/filesystem"
 import { ModelsDev } from "../provider/models"
 import { mergeDeep, pipe, unique } from "remeda"
diff --git a/packages/opencode/src/env/index.ts b/packages/opencode/src/env/index.ts
deleted file mode 100644
index 003b59fc71c9..000000000000
--- a/packages/opencode/src/env/index.ts
+++ /dev/null
@@ -1,28 +0,0 @@
-import { Instance } from "../project/instance"
-
-export namespace Env {
-  const state = Instance.state(() => {
-    // Create a shallow copy to isolate environment per instance
-    // Prevents parallel tests from interfering with each other's env vars
-    return { ...process.env } as Record<string, string | undefined>
-  })
-
-  export function get(key: string) {
-    const env = state()
-    return env[key]
-  }
-
-  export function all() {
-    return state()
-  }
-
-  export function set(key: string, value: string) {
-    const env = state()
-    env[key] = value
-  }
-
-  export function remove(key: string) {
-    const env = state()
-    delete env[key]
-  }
-}
diff --git a/packages/opencode/src/ide/index.ts b/packages/opencode/src/ide/index.ts
index 0837b2aa5ff5..f602200be262 100644
--- a/packages/opencode/src/ide/index.ts
+++ b/packages/opencode/src/ide/index.ts
@@ -4,7 +4,6 @@ import { spawn } from "bun"
 import z from "zod"
 import { NamedError } from "@opencode-ai/util/error"
 import { Log } from "../util/log"
-
 const SUPPORTED_IDES = [
   { name: "Windsurf" as const, cmd: "windsurf" },
   { name: "Visual Studio Code - Insiders" as const, cmd: "code-insiders" },
diff --git a/packages/opencode/src/index.ts b/packages/opencode/src/index.ts
index 39e77782f599..38fad782e5db 100644
--- a/packages/opencode/src/index.ts
+++ b/packages/opencode/src/index.ts
@@ -19,6 +19,7 @@ import { McpCommand } from "./cli/cmd/mcp"
 import { GithubCommand } from "./cli/cmd/github"
 import { ExportCommand } from "./cli/cmd/export"
 import { ImportCommand } from "./cli/cmd/import"
+
 import { AttachCommand } from "./cli/cmd/tui/attach"
 import { TuiThreadCommand } from "./cli/cmd/tui/thread"
 import { AcpCommand } from "./cli/cmd/acp"
@@ -72,8 +73,8 @@ const cli = yargs(hideBin(process.argv))
       })(),
     })
 
-    process.env.AGENT = "1"
-    process.env.OPENCODE = "1"
+    process.env["AGENT"] = "1"
+    process.env["OPENCODE"] = "1"
 
     Log.Default.info("opencode", {
       version: Installation.VERSION,
diff --git a/packages/opencode/src/provider/provider.ts b/packages/opencode/src/provider/provider.ts
index d94d0cbb2239..15c681e3f43f 100644
--- a/packages/opencode/src/provider/provider.ts
+++ b/packages/opencode/src/provider/provider.ts
@@ -10,7 +10,7 @@ import { Plugin } from "../plugin"
 import { ModelsDev } from "./models"
 import { NamedError } from "@opencode-ai/util/error"
 import { Auth } from "../auth"
-import { Env } from "../env"
+
 import { Instance } from "../project/instance"
 import { Flag } from "../flag/flag"
 import { iife } from "@/util/iife"
@@ -59,9 +59,12 @@ export namespace Provider {
 
   function googleVertexVars(options: Record<string, any>) {
     const project =
-      options["project"] ?? Env.get("GOOGLE_CLOUD_PROJECT") ?? Env.get("GCP_PROJECT") ?? Env.get("GCLOUD_PROJECT")
+      options["project"] ??
+      process.env["GOOGLE_CLOUD_PROJECT"] ??
+      process.env["GCP_PROJECT"] ??
+      process.env["GCLOUD_PROJECT"]
     const location =
-      options["location"] ?? Env.get("GOOGLE_CLOUD_LOCATION") ?? Env.get("VERTEX_LOCATION") ?? "us-central1"
+      options["location"] ?? process.env["GOOGLE_CLOUD_LOCATION"] ?? process.env["VERTEX_LOCATION"] ?? "us-central1"
     const endpoint = location === "global" ? "aiplatform.googleapis.com" : `${location}-aiplatform.googleapis.com`
 
     return {
@@ -76,7 +79,7 @@ export namespace Provider {
     if (typeof raw !== "string") return raw
     const vars = model.providerID === "google-vertex" ? googleVertexVars(options) : undefined
     return raw.replace(/\$\{([^}]+)\}/g, (match, key) => {
-      const val = Env.get(String(key)) ?? vars?.[String(key) as keyof typeof vars]
+      const val = process.env[String(key)] ?? vars?.[String(key) as keyof typeof vars]
       return val ?? match
     })
   }
@@ -127,7 +130,7 @@ export namespace Provider {
     },
     async opencode(input) {
       const hasKey = await (async () => {
-        const env = Env.all()
+        const env = process.env
         if (input.env.some((item) => env[item])) return true
         if (await Auth.get(input.id)) return true
         const config = await Config.get()
@@ -190,7 +193,7 @@ export namespace Provider {
       }
     },
     "azure-cognitive-services": async () => {
-      const resourceName = Env.get("AZURE_COGNITIVE_SERVICES_RESOURCE_NAME")
+      const resourceName = process.env["AZURE_COGNITIVE_SERVICES_RESOURCE_NAME"]
       return {
         autoload: false,
         async getModel(sdk: any, modelID: string, options?: Record<string, any>) {
@@ -213,32 +216,30 @@ export namespace Provider {
 
       // Region precedence: 1) config file, 2) env var, 3) default
       const configRegion = providerConfig?.options?.region
-      const envRegion = Env.get("AWS_REGION")
+      const envRegion = process.env["AWS_REGION"]
       const defaultRegion = configRegion ?? envRegion ?? "us-east-1"
 
       // Profile: config file takes precedence over env var
       const configProfile = providerConfig?.options?.profile
-      const envProfile = Env.get("AWS_PROFILE")
+      const envProfile = process.env["AWS_PROFILE"]
       const profile = configProfile ?? envProfile
 
-      const awsAccessKeyId = Env.get("AWS_ACCESS_KEY_ID")
+      const awsAccessKeyId = process.env["AWS_ACCESS_KEY_ID"]
 
-      // TODO: Using process.env directly because Env.set only updates a process.env shallow copy,
-      // until the scope of the Env API is clarified (test only or runtime?)
       const awsBearerToken = iife(() => {
-        const envToken = process.env.AWS_BEARER_TOKEN_BEDROCK
+        const envToken = process.env["AWS_BEARER_TOKEN_BEDROCK"]
         if (envToken) return envToken
         if (auth?.type === "api") {
-          process.env.AWS_BEARER_TOKEN_BEDROCK = auth.key
+          process.env["AWS_BEARER_TOKEN_BEDROCK"] = auth.key
           return auth.key
         }
         return undefined
       })
 
-      const awsWebIdentityTokenFile = Env.get("AWS_WEB_IDENTITY_TOKEN_FILE")
+      const awsWebIdentityTokenFile = process.env["AWS_WEB_IDENTITY_TOKEN_FILE"]
 
       const containerCreds = Boolean(
-        process.env.AWS_CONTAINER_CREDENTIALS_RELATIVE_URI || process.env.AWS_CONTAINER_CREDENTIALS_FULL_URI,
+        process.env["AWS_CONTAINER_CREDENTIALS_RELATIVE_URI"] || process.env["AWS_CONTAINER_CREDENTIALS_FULL_URI"],
       )
 
       if (!profile && !awsAccessKeyId && !awsBearerToken && !awsWebIdentityTokenFile && !containerCreds)
@@ -380,12 +381,15 @@ export namespace Provider {
     "google-vertex": async (provider) => {
       const project =
         provider.options?.project ??
-        Env.get("GOOGLE_CLOUD_PROJECT") ??
-        Env.get("GCP_PROJECT") ??
-        Env.get("GCLOUD_PROJECT")
+        process.env["GOOGLE_CLOUD_PROJECT"] ??
+        process.env["GCP_PROJECT"] ??
+        process.env["GCLOUD_PROJECT"]
 
       const location =
-        provider.options?.location ?? Env.get("GOOGLE_CLOUD_LOCATION") ?? Env.get("VERTEX_LOCATION") ?? "us-central1"
+        provider.options?.location ??
+        process.env["GOOGLE_CLOUD_LOCATION"] ??
+        process.env["VERTEX_LOCATION"] ??
+        "us-central1"
 
       const autoload = Boolean(project)
       if (!autoload) return { autoload: false }
@@ -414,8 +418,8 @@ export namespace Provider {
       }
     },
     "google-vertex-anthropic": async () => {
-      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 project = process.env["GOOGLE_CLOUD_PROJECT"] ?? process.env["GCP_PROJECT"] ?? process.env["GCLOUD_PROJECT"]
+      const location = process.env["GOOGLE_CLOUD_LOCATION"] ?? process.env["VERTEX_LOCATION"] ?? "global"
       const autoload = Boolean(project)
       if (!autoload) return { autoload: false }
       return {
@@ -432,19 +436,17 @@ export namespace Provider {
     },
     "sap-ai-core": async () => {
       const auth = await Auth.get("sap-ai-core")
-      // TODO: Using process.env directly because Env.set only updates a shallow copy (not process.env),
-      // until the scope of the Env API is clarified (test only or runtime?)
       const envServiceKey = iife(() => {
-        const envAICoreServiceKey = process.env.AICORE_SERVICE_KEY
+        const envAICoreServiceKey = process.env["AICORE_SERVICE_KEY"]
         if (envAICoreServiceKey) return envAICoreServiceKey
         if (auth?.type === "api") {
-          process.env.AICORE_SERVICE_KEY = auth.key
+          process.env["AICORE_SERVICE_KEY"] = auth.key
           return auth.key
         }
         return undefined
       })
-      const deploymentId = process.env.AICORE_DEPLOYMENT_ID
-      const resourceGroup = process.env.AICORE_RESOURCE_GROUP
+      const deploymentId = process.env["AICORE_DEPLOYMENT_ID"]
+      const resourceGroup = process.env["AICORE_RESOURCE_GROUP"]
 
       return {
         autoload: !!envServiceKey,
@@ -466,13 +468,13 @@ export namespace Provider {
       }
     },
     gitlab: async (input) => {
-      const instanceUrl = Env.get("GITLAB_INSTANCE_URL") || "https://gitlab.com"
+      const instanceUrl = process.env["GITLAB_INSTANCE_URL"] || "https://gitlab.com"
 
       const auth = await Auth.get(input.id)
       const apiKey = await (async () => {
         if (auth?.type === "oauth") return auth.access
         if (auth?.type === "api") return auth.key
-        return Env.get("GITLAB_TOKEN")
+        return process.env["GITLAB_TOKEN"]
       })()
 
       const config = await Config.get()
@@ -508,11 +510,11 @@ export namespace Provider {
       }
     },
     "cloudflare-workers-ai": async (input) => {
-      const accountId = Env.get("CLOUDFLARE_ACCOUNT_ID")
+      const accountId = process.env["CLOUDFLARE_ACCOUNT_ID"]
       if (!accountId) return { autoload: false }
 
       const apiKey = await iife(async () => {
-        const envToken = Env.get("CLOUDFLARE_API_KEY")
+        const envToken = process.env["CLOUDFLARE_API_KEY"]
         if (envToken) return envToken
         const auth = await Auth.get(input.id)
         if (auth?.type === "api") return auth.key
@@ -531,14 +533,14 @@ export namespace Provider {
       }
     },
     "cloudflare-ai-gateway": async (input) => {
-      const accountId = Env.get("CLOUDFLARE_ACCOUNT_ID")
-      const gateway = Env.get("CLOUDFLARE_GATEWAY_ID")
+      const accountId = process.env["CLOUDFLARE_ACCOUNT_ID"]
+      const gateway = process.env["CLOUDFLARE_GATEWAY_ID"]
 
       if (!accountId || !gateway) return { autoload: false }
 
       // Get API token from env or auth - required for authenticated gateways
       const apiToken = await (async () => {
-        const envToken = Env.get("CLOUDFLARE_API_TOKEN") || Env.get("CF_AIG_TOKEN")
+        const envToken = process.env["CLOUDFLARE_API_TOKEN"] || process.env["CF_AIG_TOKEN"]
         if (envToken) return envToken
         const auth = await Auth.get(input.id)
         if (auth?.type === "api") return auth.key
@@ -892,7 +894,7 @@ export namespace Provider {
     }
 
     // load env
-    const env = Env.all()
+    const env = process.env
     for (const [providerID, provider] of Object.entries(database)) {
       if (disabled.has(providerID)) continue
       const apiKey = provider.env.map((item) => env[item]).find(Boolean)
diff --git a/packages/opencode/src/shell/shell.ts b/packages/opencode/src/shell/shell.ts
index 2e8d48bfd921..6dd1f51cbe29 100644
--- a/packages/opencode/src/shell/shell.ts
+++ b/packages/opencode/src/shell/shell.ts
@@ -1,4 +1,5 @@
 import { Flag } from "@/flag/flag"
+
 import { lazy } from "@/util/lazy"
 import path from "path"
 import { spawn, type ChildProcess } from "child_process"
@@ -45,7 +46,7 @@ export namespace Shell {
         const bash = path.join(git, "..", "..", "bin", "bash.exe")
         if (Bun.file(bash).size) return bash
       }
-      return process.env.COMSPEC || "cmd.exe"
+      return process.env["COMSPEC"] || "cmd.exe"
     }
     if (process.platform === "darwin") return "/bin/zsh"
     const bash = Bun.which("bash")
@@ -54,13 +55,13 @@ export namespace Shell {
   }
 
   export const preferred = lazy(() => {
-    const s = process.env.SHELL
+    const s = process.env["SHELL"]
     if (s) return s
     return fallback()
   })
 
   export const acceptable = lazy(() => {
-    const s = process.env.SHELL
+    const s = process.env["SHELL"]
     if (s && !BLACKLIST.has(process.platform === "win32" ? path.win32.basename(s) : path.basename(s))) return s
     return fallback()
   })
diff --git a/packages/opencode/src/util/proxied.ts b/packages/opencode/src/util/proxied.ts
index 440a9cccedb6..c8ffdd170d15 100644
--- a/packages/opencode/src/util/proxied.ts
+++ b/packages/opencode/src/util/proxied.ts
@@ -1,3 +1,8 @@
 export function proxied() {
-  return !!(process.env.HTTP_PROXY || process.env.HTTPS_PROXY || process.env.http_proxy || process.env.https_proxy)
+  return !!(
+    process.env["HTTP_PROXY"] ||
+    process.env["HTTPS_PROXY"] ||
+    process.env["http_proxy"] ||
+    process.env["https_proxy"]
+  )
 }
diff --git a/packages/opencode/test/preload.ts b/packages/opencode/test/preload.ts
index dee7045707ea..76a6a1639df0 100644
--- a/packages/opencode/test/preload.ts
+++ b/packages/opencode/test/preload.ts
@@ -4,7 +4,7 @@ import os from "os"
 import path from "path"
 import fs from "fs/promises"
 import fsSync from "fs"
-import { afterAll } from "bun:test"
+import { afterAll, beforeEach, afterEach } from "bun:test"
 
 // Set XDG env vars FIRST, before any src/ imports
 const dir = path.join(os.tmpdir(), "opencode-test-data-" + process.pid)
@@ -63,3 +63,27 @@ Log.init({
   dev: true,
   level: "DEBUG",
 })
+
+// Snapshot env vars for isolation
+let envSnapshot: Record<string, string | undefined>
+
+beforeEach(() => {
+  envSnapshot = { ...process.env }
+})
+
+afterEach(() => {
+  // Remove keys added during test
+  for (const key in process.env) {
+    if (!(key in envSnapshot)) {
+      delete process.env[key]
+    }
+  }
+  // Restore original values
+  for (const key in envSnapshot) {
+    if (envSnapshot[key] === undefined) {
+      delete process.env[key]
+    } else {
+      process.env[key] = envSnapshot[key]
+    }
+  }
+})
diff --git a/packages/opencode/test/provider/amazon-bedrock.test.ts b/packages/opencode/test/provider/amazon-bedrock.test.ts
index d1d3cc41c45c..4975c8cf0518 100644
--- a/packages/opencode/test/provider/amazon-bedrock.test.ts
+++ b/packages/opencode/test/provider/amazon-bedrock.test.ts
@@ -5,7 +5,6 @@ import { unlink } from "fs/promises"
 import { tmpdir } from "../fixture/fixture"
 import { Instance } from "../../src/project/instance"
 import { Provider } from "../../src/provider/provider"
-import { Env } from "../../src/env"
 import { Global } from "../../src/global"
 
 test("Bedrock: config region takes precedence over AWS_REGION env var", async () => {
@@ -29,8 +28,8 @@ test("Bedrock: config region takes precedence over AWS_REGION env var", async ()
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("AWS_REGION", "us-east-1")
-      Env.set("AWS_PROFILE", "default")
+      process.env["AWS_REGION"] = "us-east-1"
+      process.env["AWS_PROFILE"] = "default"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -54,8 +53,8 @@ test("Bedrock: falls back to AWS_REGION env var when no config region", async ()
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("AWS_REGION", "eu-west-1")
-      Env.set("AWS_PROFILE", "default")
+      process.env["AWS_REGION"] = "eu-west-1"
+      process.env["AWS_PROFILE"] = "default"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -109,9 +108,9 @@ test("Bedrock: loads when bearer token from auth.json is present", async () => {
     await Instance.provide({
       directory: tmp.path,
       init: async () => {
-        Env.set("AWS_PROFILE", "")
-        Env.set("AWS_ACCESS_KEY_ID", "")
-        Env.set("AWS_BEARER_TOKEN_BEDROCK", "")
+        process.env["AWS_PROFILE"] = ""
+        process.env["AWS_ACCESS_KEY_ID"] = ""
+        process.env["AWS_BEARER_TOKEN_BEDROCK"] = ""
       },
       fn: async () => {
         const providers = await Provider.list()
@@ -155,8 +154,8 @@ test("Bedrock: config profile takes precedence over AWS_PROFILE env var", async
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("AWS_PROFILE", "default")
-      Env.set("AWS_ACCESS_KEY_ID", "test-key-id")
+      process.env["AWS_PROFILE"] = "default"
+      process.env["AWS_ACCESS_KEY_ID"] = "test-key-id"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -187,7 +186,7 @@ test("Bedrock: includes custom endpoint in options when specified", async () =>
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("AWS_PROFILE", "default")
+      process.env["AWS_PROFILE"] = "default"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -220,10 +219,10 @@ test("Bedrock: autoloads when AWS_WEB_IDENTITY_TOKEN_FILE is present", async ()
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("AWS_WEB_IDENTITY_TOKEN_FILE", "/var/run/secrets/eks.amazonaws.com/serviceaccount/token")
-      Env.set("AWS_ROLE_ARN", "arn:aws:iam::123456789012:role/my-eks-role")
-      Env.set("AWS_PROFILE", "")
-      Env.set("AWS_ACCESS_KEY_ID", "")
+      process.env["AWS_WEB_IDENTITY_TOKEN_FILE"] = "/var/run/secrets/eks.amazonaws.com/serviceaccount/token"
+      process.env["AWS_ROLE_ARN"] = "arn:aws:iam::123456789012:role/my-eks-role"
+      process.env["AWS_PROFILE"] = ""
+      process.env["AWS_ACCESS_KEY_ID"] = ""
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -263,7 +262,7 @@ test("Bedrock: model with us. prefix should not be double-prefixed", async () =>
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("AWS_PROFILE", "default")
+      process.env["AWS_PROFILE"] = "default"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -300,7 +299,7 @@ test("Bedrock: model with global. prefix should not be prefixed", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("AWS_PROFILE", "default")
+      process.env["AWS_PROFILE"] = "default"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -336,7 +335,7 @@ test("Bedrock: model with eu. prefix should not be double-prefixed", async () =>
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("AWS_PROFILE", "default")
+      process.env["AWS_PROFILE"] = "default"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -372,7 +371,7 @@ test("Bedrock: model without prefix in US region should get us. prefix added", a
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("AWS_PROFILE", "default")
+      process.env["AWS_PROFILE"] = "default"
     },
     fn: async () => {
       const providers = await Provider.list()
diff --git a/packages/opencode/test/provider/gitlab-duo.test.ts b/packages/opencode/test/provider/gitlab-duo.test.ts
index c512a45909d8..51edc8a36946 100644
--- a/packages/opencode/test/provider/gitlab-duo.test.ts
+++ b/packages/opencode/test/provider/gitlab-duo.test.ts
@@ -4,7 +4,6 @@ import path from "path"
 import { tmpdir } from "../fixture/fixture"
 import { Instance } from "../../src/project/instance"
 import { Provider } from "../../src/provider/provider"
-import { Env } from "../../src/env"
 import { Global } from "../../src/global"
 
 test("GitLab Duo: loads provider with API key from environment", async () => {
@@ -21,7 +20,7 @@ test("GitLab Duo: loads provider with API key from environment", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("GITLAB_TOKEN", "test-gitlab-token")
+      process.env["GITLAB_TOKEN"] = "test-gitlab-token"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -52,8 +51,8 @@ test("GitLab Duo: config instanceUrl option sets baseURL", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("GITLAB_TOKEN", "test-token")
-      Env.set("GITLAB_INSTANCE_URL", "https://gitlab.example.com")
+      process.env["GITLAB_TOKEN"] = "test-token"
+      process.env["GITLAB_INSTANCE_URL"] = "https://gitlab.example.com"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -91,7 +90,7 @@ test("GitLab Duo: loads with OAuth token from auth.json", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("GITLAB_TOKEN", "")
+      process.env["GITLAB_TOKEN"] = ""
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -126,7 +125,7 @@ test("GitLab Duo: loads with Personal Access Token from auth.json", async () =>
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("GITLAB_TOKEN", "")
+      process.env["GITLAB_TOKEN"] = ""
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -158,7 +157,7 @@ test("GitLab Duo: supports self-hosted instance configuration", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("GITLAB_INSTANCE_URL", "https://gitlab.company.internal")
+      process.env["GITLAB_INSTANCE_URL"] = "https://gitlab.company.internal"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -189,7 +188,7 @@ test("GitLab Duo: config apiKey takes precedence over environment variable", asy
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("GITLAB_TOKEN", "env-token")
+      process.env["GITLAB_TOKEN"] = "env-token"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -222,7 +221,7 @@ test("GitLab Duo: supports feature flags configuration", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("GITLAB_TOKEN", "test-token")
+      process.env["GITLAB_TOKEN"] = "test-token"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -247,7 +246,7 @@ test("GitLab Duo: has multiple agentic chat models available", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("GITLAB_TOKEN", "test-token")
+      process.env["GITLAB_TOKEN"] = "test-token"
     },
     fn: async () => {
       const providers = await Provider.list()
diff --git a/packages/opencode/test/provider/provider.test.ts b/packages/opencode/test/provider/provider.test.ts
index 0a5aa415131c..76b7fb0ebe0a 100644
--- a/packages/opencode/test/provider/provider.test.ts
+++ b/packages/opencode/test/provider/provider.test.ts
@@ -4,7 +4,6 @@ import path from "path"
 import { tmpdir } from "../fixture/fixture"
 import { Instance } from "../../src/project/instance"
 import { Provider } from "../../src/provider/provider"
-import { Env } from "../../src/env"
 
 test("provider loaded from env variable", async () => {
   await using tmp = await tmpdir({
@@ -20,7 +19,7 @@ test("provider loaded from env variable", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -75,7 +74,7 @@ test("disabled_providers excludes provider", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -99,8 +98,8 @@ test("enabled_providers restricts to only listed providers", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
-      Env.set("OPENAI_API_KEY", "test-openai-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
+      process.env["OPENAI_API_KEY"] = "test-openai-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -129,7 +128,7 @@ test("model whitelist filters models for provider", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -160,7 +159,7 @@ test("model blacklist excludes specific models", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -195,7 +194,7 @@ test("custom model alias via config", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -270,7 +269,7 @@ test("env variable takes precedence, config merges options", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "env-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "env-api-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -295,7 +294,7 @@ test("getModel returns model for valid provider/model", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const model = await Provider.getModel("anthropic", "claude-sonnet-4-20250514")
@@ -322,7 +321,7 @@ test("getModel throws ModelNotFoundError for invalid model", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       expect(Provider.getModel("anthropic", "nonexistent-model")).rejects.toThrow()
@@ -375,7 +374,7 @@ test("defaultModel returns first available model when no config set", async () =
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const model = await Provider.defaultModel()
@@ -400,7 +399,7 @@ test("defaultModel respects config model setting", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const model = await Provider.defaultModel()
@@ -515,7 +514,7 @@ test("model options are merged from existing model", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -544,7 +543,7 @@ test("provider removed when all models filtered out", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -567,7 +566,7 @@ test("closest finds model by partial match", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const result = await Provider.closest("anthropic", ["sonnet-4"])
@@ -622,7 +621,7 @@ test("getModel uses realIdByKey for aliased models", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -737,7 +736,7 @@ test("model inherits properties from existing database model", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -765,7 +764,7 @@ test("disabled_providers prevents loading even with env var", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("OPENAI_API_KEY", "test-openai-key")
+      process.env["OPENAI_API_KEY"] = "test-openai-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -789,8 +788,8 @@ test("enabled_providers with empty array allows no providers", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
-      Env.set("OPENAI_API_KEY", "test-openai-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
+      process.env["OPENAI_API_KEY"] = "test-openai-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -819,7 +818,7 @@ test("whitelist and blacklist can be combined", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -928,7 +927,7 @@ test("getSmallModel returns appropriate small model", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const model = await Provider.getSmallModel("anthropic")
@@ -953,7 +952,7 @@ test("getSmallModel respects config small_model override", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const model = await Provider.getSmallModel("anthropic")
@@ -1001,8 +1000,8 @@ test("multiple providers can be configured simultaneously", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-anthropic-key")
-      Env.set("OPENAI_API_KEY", "test-openai-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-anthropic-key"
+      process.env["OPENAI_API_KEY"] = "test-openai-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -1080,7 +1079,7 @@ test("model alias name defaults to alias key when id differs", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -1120,7 +1119,7 @@ test("provider with multiple env var options only includes apiKey when single en
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("MULTI_ENV_KEY_1", "test-key")
+      process.env["MULTI_ENV_KEY_1"] = "test-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -1162,7 +1161,7 @@ test("provider with single env var includes apiKey automatically", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("SINGLE_ENV_KEY", "my-api-key")
+      process.env["SINGLE_ENV_KEY"] = "my-api-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -1199,7 +1198,7 @@ test("model cost overrides existing cost values", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -1278,9 +1277,9 @@ test("disabled_providers and enabled_providers interaction", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-anthropic")
-      Env.set("OPENAI_API_KEY", "test-openai")
-      Env.set("GOOGLE_GENERATIVE_AI_API_KEY", "test-google")
+      process.env["ANTHROPIC_API_KEY"] = "test-anthropic"
+      process.env["OPENAI_API_KEY"] = "test-openai"
+      process.env["GOOGLE_GENERATIVE_AI_API_KEY"] = "test-google"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -1437,7 +1436,7 @@ test("provider env fallback - second env var used if first missing", async () =>
     directory: tmp.path,
     init: async () => {
       // Only set fallback, not primary
-      Env.set("FALLBACK_KEY", "fallback-api-key")
+      process.env["FALLBACK_KEY"] = "fallback-api-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -1461,7 +1460,7 @@ test("getModel returns consistent results", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const model1 = await Provider.getModel("anthropic", "claude-sonnet-4-20250514")
@@ -1522,7 +1521,7 @@ test("ModelNotFoundError includes suggestions for typos", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       try {
@@ -1550,7 +1549,7 @@ test("ModelNotFoundError for provider includes suggestions", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       try {
@@ -1598,7 +1597,7 @@ test("getProvider returns provider info", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const provider = await Provider.getProvider("anthropic")
@@ -1622,7 +1621,7 @@ test("closest returns undefined when no partial match found", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const result = await Provider.closest("anthropic", ["nonexistent-xyz-model"])
@@ -1645,7 +1644,7 @@ test("closest checks multiple query terms in order", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       // First term won't match, second will
@@ -1717,7 +1716,7 @@ test("provider options are deeply merged", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -1755,7 +1754,7 @@ test("custom model inherits npm package from models.dev provider config", async
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("OPENAI_API_KEY", "test-api-key")
+      process.env["OPENAI_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -1790,7 +1789,7 @@ test("custom model inherits api.url from models.dev provider", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("OPENROUTER_API_KEY", "test-api-key")
+      process.env["OPENROUTER_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -1824,7 +1823,7 @@ test("model variants are generated for reasoning models", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -1862,7 +1861,7 @@ test("model variants can be disabled via config", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -1905,7 +1904,7 @@ test("model variants can be customized via config", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -1944,7 +1943,7 @@ test("disabled key is stripped from variant config", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -1982,7 +1981,7 @@ test("all variants can be disabled via config", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -2020,7 +2019,7 @@ test("variant config merges with generated variants", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+      process.env["ANTHROPIC_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -2058,7 +2057,7 @@ test("variants filtered in second pass for database models", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("OPENAI_API_KEY", "test-api-key")
+      process.env["OPENAI_API_KEY"] = "test-api-key"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -2162,7 +2161,7 @@ test("Google Vertex: retains baseURL for custom proxy", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("GOOGLE_APPLICATION_CREDENTIALS", "test-creds")
+      process.env["GOOGLE_APPLICATION_CREDENTIALS"] = "test-creds"
     },
     fn: async () => {
       const providers = await Provider.list()
@@ -2207,7 +2206,7 @@ test("Google Vertex: supports OpenAI compatible models", async () => {
   await Instance.provide({
     directory: tmp.path,
     init: async () => {
-      Env.set("GOOGLE_APPLICATION_CREDENTIALS", "test-creds")
+      process.env["GOOGLE_APPLICATION_CREDENTIALS"] = "test-creds"
     },
     fn: async () => {
       const providers = await Provider.list()