diff --git a/packages/core/src/environment/unavailable.ts b/packages/core/src/environment/unavailable.ts
new file mode 100644
index 00000000000..59db611a77f
--- /dev/null
+++ b/packages/core/src/environment/unavailable.ts
@@ -0,0 +1,17 @@
+import { Effect, Layer, PlatformError } from "effect"
+import { ChildProcessSpawner, make } from "effect/unstable/process/ChildProcessSpawner"
+
+export const spawner = make(() =>
+  Effect.fail(
+    PlatformError.systemError({
+      _tag: "Unknown",
+      module: "Environment",
+      method: "spawn",
+      description: "This location has no execution plane: no workspace is attached and the host cannot spawn processes",
+    }),
+  ),
+)
+
+export const layer = Layer.succeed(ChildProcessSpawner, spawner)
+
+export * as EnvironmentUnavailable from "./unavailable.js"
diff --git a/packages/core/src/mcp/index.ts b/packages/core/src/mcp/index.ts
index 9504e79e89f..4685bc31eb5 100644
--- a/packages/core/src/mcp/index.ts
+++ b/packages/core/src/mcp/index.ts
@@ -165,8 +165,6 @@ export const Options = Schema.Struct({
       version: Schema.String,
     }),
   ),
-  /** Set false on runtimes that cannot spawn child processes; local (stdio) servers report failed instead of connecting. */
-  stdio: Schema.optional(Schema.Boolean),
 })
 export type Options = typeof Options.Type
 
@@ -500,11 +498,6 @@ export const layer = (options?: Options) =>
 
       const startServer = (name: ServerName, entry: ServerEntry) =>
         Effect.gen(function* () {
-          if (options?.stdio === false && entry.config.type === "local") {
-            entry.status = { status: "failed", error: "stdio MCP servers are unavailable in this runtime" }
-            yield* bus.publish(McpEvent.StatusChanged, { server: name }).pipe(Effect.ignore)
-            return
-          }
           // Announce the handshake so connect() and credential reconnects don't show a stale
           // disabled/failed status for the duration of the connection attempt.
           entry.status = { status: "pending" }
diff --git a/packages/core/src/session.ts b/packages/core/src/session.ts
index bbffc947ec5..ebe91c5ccba 100644
--- a/packages/core/src/session.ts
+++ b/packages/core/src/session.ts
@@ -639,7 +639,9 @@ const layer = Layer.effect(
             yield* execution.awaitIdle(input.sessionID)
             const started = yield* Effect.gen(function* () {
               const shell = yield* Shell.Service
-              return yield* shell.create({ command: input.command, cwd: session.location.directory, timeout: 0 })
+              return yield* shell
+                .create({ command: input.command, cwd: session.location.directory, timeout: 0 })
+                .pipe(Effect.orDie)
             }).pipe(Effect.provide(locations.get(session.location)))
             yield* bus.publish(
               SessionEvent.Shell.Started,
diff --git a/packages/core/src/shell.ts b/packages/core/src/shell.ts
index 38e8c1cc0db..d1733732be0 100644
--- a/packages/core/src/shell.ts
+++ b/packages/core/src/shell.ts
@@ -5,6 +5,7 @@ import { Context, Deferred, Duration, Effect, Fiber, Layer, Schema, Stream } fro
 import { ChildProcess } from "effect/unstable/process"
 import { produce } from "immer"
 import { Shell } from "@opencode-ai/schema/shell"
+import { AppProcess } from "@opencode-ai/util/process"
 import { makeLocationNode } from "@opencode-ai/util/effect/app-node"
 import { Config } from "./config.js"
 import { Bus } from "./bus.js"
@@ -50,7 +51,7 @@ export interface Interface {
   readonly create: <E = never, R = never>(
     input: Shell.CreateInput,
     before?: (input: ShellCreateBefore) => Effect.Effect<void, E, R>,
-  ) => Effect.Effect<Shell.Info, E, R>
+  ) => Effect.Effect<Shell.Info, E | AppProcess.AppProcessError, R>
   // Currently running commands only; exited shells are retained for get/output but excluded here.
   readonly list: () => Effect.Effect<Shell.Info[]>
   readonly get: (id: Shell.ID) => Effect.Effect<Shell.Info, NotFoundError>
@@ -215,19 +216,23 @@ export const layer = (options?: ShellSelect.Options) =>
         // Spawn through the Environment and stream combined output to the file. The handle is scope-bound, so
         // the managing fiber keeps its scope open until the command terminates (it awaits `done` at the
         // end). `create` returns once `ready` resolves with the registered session.
-        const ready = Deferred.makeUnsafe<Active>()
+        const ready = Deferred.makeUnsafe<Active, AppProcess.AppProcessError>()
         runFork(
           Effect.scoped(
             Effect.gen(function* () {
-              const handle = yield* environment.spawner.spawn(
-                ChildProcess.make(invocation.shell, args, {
-                  cwd: invocation.cwd,
-                  env: invocation.env,
-                  stdin: "ignore",
-                  detached: process.platform !== "win32",
-                  forceKillAfter: Duration.seconds(3),
-                }),
-              )
+              const handle = yield* environment.spawner
+                .spawn(
+                  ChildProcess.make(invocation.shell, args, {
+                    cwd: invocation.cwd,
+                    env: invocation.env,
+                    stdin: "ignore",
+                    detached: process.platform !== "win32",
+                    forceKillAfter: Duration.seconds(3),
+                  }),
+                )
+                .pipe(
+                  Effect.mapError((cause) => new AppProcess.AppProcessError({ command: invocation.command, cause })),
+                )
               const session: Active = {
                 info: produce(info, (draft) => {
                   draft.pid = handle.pid
@@ -329,7 +334,7 @@ export const layer = (options?: ShellSelect.Options) =>
               // release (kill) the process before its exit is observed.
               yield* Deferred.await(session.done).pipe(Effect.catch(() => Effect.void))
             }),
-          ).pipe(Effect.catch(() => Effect.void)),
+          ).pipe(Effect.catchTag("AppProcessError", (error) => Deferred.fail(ready, error))),
         )
 
         const session = yield* Deferred.await(ready)
diff --git a/packages/core/test/environment.test.ts b/packages/core/test/environment.test.ts
index 90246bd02be..1571df10f53 100644
--- a/packages/core/test/environment.test.ts
+++ b/packages/core/test/environment.test.ts
@@ -1,9 +1,10 @@
 import fs from "node:fs/promises"
 import { describe, expect } from "bun:test"
 import { Effect } from "effect"
-import { ChildProcessSpawner } from "effect/unstable/process"
+import { ChildProcess, ChildProcessSpawner } from "effect/unstable/process"
 import { CrossSpawnSpawner } from "@opencode-ai/util/cross-spawn-spawner"
 import { LayerNode } from "@opencode-ai/util/effect/layer-node"
+import { EnvironmentUnavailable } from "../src/environment/unavailable"
 import {
   execDefaults,
   Failed,
@@ -35,6 +36,19 @@ describe("typeFollowing", () => {
   )
 })
 
+describe("no execution plane", () => {
+  it.effect("fails spawn with a typed location error", () =>
+    Effect.gen(function* () {
+      const error = yield* EnvironmentUnavailable.spawner
+        .spawn(ChildProcess.make("echo", ["hello"]))
+        .pipe(Effect.flip)
+
+      expect(error._tag).toBe("PlatformError")
+      expect(error.message).toContain("location has no execution plane")
+    }),
+  )
+})
+
 environmentConformance("memory environment", () =>
   Effect.sync(() => {
     const driver = makeMemoryDriver()
diff --git a/packages/core/test/mcp.test.ts b/packages/core/test/mcp.test.ts
index 9c2e49c628b..cc879b8d388 100644
--- a/packages/core/test/mcp.test.ts
+++ b/packages/core/test/mcp.test.ts
@@ -23,6 +23,7 @@ import { ID, type Payload } from "@opencode-ai/schema/event"
 import { Form } from "@opencode-ai/core/form"
 import { Integration } from "@opencode-ai/core/integration"
 import { Environment } from "@opencode-ai/core/environment/index"
+import { EnvironmentUnavailable } from "@opencode-ai/core/environment/unavailable"
 import { Location } from "@opencode-ai/core/location"
 import { MCP } from "@opencode-ai/core/mcp/index"
 import { MCPClient } from "@opencode-ai/core/mcp/client"
@@ -478,6 +479,27 @@ test("spawns local MCP servers through the location environment", async () => {
   expect(command.options.env).toEqual({ MCP_LOCATION_TEST: "configured" })
 })
 
+test("reports a local MCP server as failed when the location has no execution plane", async () => {
+  const config = new ConfigMCP.Local({ type: "local", command: ["example-mcp"] })
+  const driver = Environment.makeMemoryDriver()
+  const environment = Layer.succeed(
+    Environment.Service,
+    Environment.Service.of({ files: Environment.makeFiles(driver), spawner: EnvironmentUnavailable.spawner }),
+  )
+
+  await Effect.runPromise(
+    Effect.gen(function* () {
+      const service = yield* MCP.Service
+      yield* service.tools()
+      const status = (yield* service.servers()).find((server) => server.name === "resources")?.status
+      expect(status).toEqual({
+        status: "failed",
+        error: expect.stringContaining("location has no execution plane"),
+      })
+    }).pipe(Effect.provide(resourceMcpLayer(config, undefined, undefined, { environment }))),
+  )
+})
+
 test("rejects sends before the stdio transport is started", async () => {
   await Effect.runPromise(
     Effect.scoped(
diff --git a/packages/server/src/handlers/shell.ts b/packages/server/src/handlers/shell.ts
index 4b0f83bed5e..96d7530cd81 100644
--- a/packages/server/src/handlers/shell.ts
+++ b/packages/server/src/handlers/shell.ts
@@ -21,7 +21,9 @@ export const ShellHandler = HttpApiBuilder.group(Api, "server.shell", (handlers)
         Effect.fn(function* (ctx) {
           const shell = yield* Shell.Service
           const location = yield* Location.Service
-          return yield* response(shell.create({ ...ctx.payload, cwd: ctx.payload.cwd || location.directory }))
+          return yield* response(
+            shell.create({ ...ctx.payload, cwd: ctx.payload.cwd || location.directory }).pipe(Effect.orDie),
+          )
         }),
       )
       .handle(
diff --git a/packages/server/src/options.ts b/packages/server/src/options.ts
index 5ed50164a3c..96a70bd1800 100644
--- a/packages/server/src/options.ts
+++ b/packages/server/src/options.ts
@@ -40,11 +40,5 @@ export const ServerOptions = Schema.Struct({
       fff: Schema.optional(Schema.Boolean),
     }),
   ),
-  mcp: Schema.optional(
-    Schema.Struct({
-      /** Set false on runtimes that cannot spawn child processes; local (stdio) MCP servers report failed instead of connecting. */
-      stdio: Schema.optional(Schema.Boolean),
-    }),
-  ),
 })
 export type ServerOptions = typeof ServerOptions.Type
diff --git a/packages/server/src/routes.ts b/packages/server/src/routes.ts
index dd9272e3103..b91ff0bd7d2 100644
--- a/packages/server/src/routes.ts
+++ b/packages/server/src/routes.ts
@@ -120,7 +120,6 @@ function makeRoutes<AuthError, AuthServices>(
           name: options.app?.name ?? "opencode",
           version: options.app?.version ?? "unknown",
         },
-        stdio: options.mcp?.stdio,
       }),
     ],
     [PluginRuntime.node, PluginRuntime.layerWithCell(pluginRuntimeCell)],
diff --git a/packages/server/src/workerd.ts b/packages/server/src/workerd.ts
index 6ed7fefde71..fa628f31d4f 100644
--- a/packages/server/src/workerd.ts
+++ b/packages/server/src/workerd.ts
@@ -5,12 +5,13 @@ import { ConfigPluginSource } from "@opencode-ai/core/config/plugin/source"
 import { Database } from "@opencode-ai/core/database/database"
 import { sqliteLayer } from "@opencode-ai/core/database/sqlite.workerd"
 import type { DurableObjectStorage } from "@opencode-ai/core/database/sqlite.workerd"
+import { EnvironmentUnavailable } from "@opencode-ai/core/environment/unavailable"
 import { FileSystem } from "@opencode-ai/core/filesystem"
 import { FileSystemSearch } from "@opencode-ai/core/filesystem/search"
 import { Pty } from "@opencode-ai/core/pty"
-import { Shell } from "@opencode-ai/core/shell"
 import { Snapshot } from "@opencode-ai/core/snapshot"
 import { Vcs } from "@opencode-ai/core/vcs"
+import { CrossSpawnSpawner } from "@opencode-ai/util/cross-spawn-spawner"
 import type { LayerNode } from "@opencode-ai/util/effect/layer-node"
 import { ServerFetch } from "./fetch"
 import type { ServerOptions } from "./options"
@@ -24,10 +25,11 @@ import type { ServerOptions } from "./options"
  * - Watcher and fff are disabled through their existing option flags; pty, fff,
  *   shell-parser, photon, and process-lock native modules resolve to inert
  *   stubs under the `workerd` bundle condition.
- * - Shell, FileSystem, FileSystemSearch, and Pty fail with a clear defect until
- *   a remote sandbox backs them; Snapshot and Vcs degrade to no-op results.
+ * - Bare locations use a typed no-execution-plane process spawner; FileSystem,
+ *   FileSystemSearch, and Pty fail with a clear defect until a remote sandbox
+ *   backs them; Snapshot and Vcs degrade to no-op results.
  * - Config is injected as a string (no filesystem); plugin discovery is
- *   precompiled-only and MCP is restricted to remote transports.
+ *   precompiled-only, and stdio MCP reports the same no-plane failure as Shell.
  *
  * Bundle with the `workerd` condition, e.g.
  * `bun build src/workerd.ts --conditions=workerd --target=node`
@@ -67,9 +69,6 @@ export function serverOptions(options: Options): ServerOptions {
     events: { persist: true },
     config: { content: options.config?.content },
     models: options.models,
-    // No child processes on workerd: local (stdio) MCP servers report failed
-    // instead of connecting; remote transports work unchanged.
-    mcp: { stdio: false },
   }
 }
 
@@ -77,9 +76,9 @@ export function serverOptions(options: Options): ServerOptions {
 export function replacements(options: Options): LayerNode.Replacements {
   return [
     [Database.node, Database.configuredClient(sqliteLayer({ storage: options.storage }))],
+    [CrossSpawnSpawner.node, EnvironmentUnavailable.layer],
     [Snapshot.node, Snapshot.noopLayer],
     [Vcs.node, vcsLayer],
-    [Shell.node, shellLayer],
     [FileSystem.node, fileSystemLayer],
     [FileSystemSearch.node, fileSystemSearchLayer],
     [Pty.node, ptyLayer],
@@ -102,22 +101,6 @@ const vcsLayer = Layer.succeed(
   }),
 )
 
-// Shell commands need a real process; queries for unknown IDs stay typed while
-// creation is a defect until a remote sandbox backs them.
-const shellLayer = Layer.succeed(
-  Shell.Service,
-  Shell.Service.of({
-    name: () => Effect.succeed("unsupported"),
-    create: () => unavailable("Shell.create"),
-    list: () => Effect.succeed([]),
-    get: (id) => Effect.fail(new Shell.NotFoundError({ id })),
-    wait: (id) => Effect.fail(new Shell.NotFoundError({ id })),
-    timeout: (id) => Effect.fail(new Shell.NotFoundError({ id })),
-    output: (id) => Effect.fail(new Shell.NotFoundError({ id })),
-    remove: (id) => Effect.fail(new Shell.NotFoundError({ id })),
-  }),
-)
-
 // The Location-scoped filesystem has no local worktree to serve until a remote
 // sandbox backs it.
 const fileSystemLayer = Layer.succeed(
diff --git a/packages/workerd-spike/test/spike.test.ts b/packages/workerd-spike/test/spike.test.ts
index f9f5d25d470..91f3513b105 100644
--- a/packages/workerd-spike/test/spike.test.ts
+++ b/packages/workerd-spike/test/spike.test.ts
@@ -184,6 +184,25 @@ it("runs a full prompt turn against a fake provider and reads the durable log",
   expect(eventTypes).toContain("log.synced")
 })
 
+it("fails a shell command through the no-execution-plane spawner and leaves the session usable", async () => {
+  const sessionID = await createSession()
+  const shell = await request(`/api/session/${sessionID}/shell`, {
+    method: "POST",
+    body: JSON.stringify({ command: "pwd" }),
+  })
+  expect(shell.status).toBe(500)
+
+  mockLLM()
+  const prompt = await request(`/api/session/${sessionID}/prompt`, {
+    method: "POST",
+    body: JSON.stringify({ text: "Say hello after the shell failure" }),
+  })
+  expect(prompt.status).toBe(200)
+  const wait = await request(`/api/session/${sessionID}/wait`, { method: "POST" })
+  expect(wait.status).toBe(204)
+  expect((await readLog(sessionID)).map((item) => item.type)).toContain("session.execution.succeeded")
+})
+
 // A5 question 1 (ack-then-continue): the Slack flow returns the prompt request
 // immediately and lets the turn continue inside the DO with no request held
 // open. The turn runs on the coordinator's background fiber in the app layer