diff --git a/packages/opencode/src/file/watcher.ts b/packages/opencode/src/file/watcher.ts
index 146d7b4d0758..ecbf76424c55 100644
--- a/packages/opencode/src/file/watcher.ts
+++ b/packages/opencode/src/file/watcher.ts
@@ -4,7 +4,6 @@ import { createWrapper } from "@parcel/watcher/wrapper"
 import type ParcelWatcher from "@parcel/watcher"
 import { readdir } from "fs/promises"
 import path from "path"
-import z from "zod"
 import { Bus } from "@/bus"
 import { BusEvent } from "@/bus/bus-event"
 import { InstanceState } from "@/effect/instance-state"
diff --git a/packages/opencode/src/installation/index.ts b/packages/opencode/src/installation/index.ts
index be3bc47693a3..e8c434276818 100644
--- a/packages/opencode/src/installation/index.ts
+++ b/packages/opencode/src/installation/index.ts
@@ -4,7 +4,6 @@ import { CrossSpawnSpawner } from "@opencode-ai/core/cross-spawn-spawner"
 import { withTransientReadRetry } from "@/util/effect-http-client"
 import { ChildProcess, ChildProcessSpawner } from "effect/unstable/process"
 import path from "path"
-import z from "zod"
 import { BusEvent } from "@/bus/bus-event"
 import { Flag } from "@opencode-ai/core/flag/flag"
 import * as Log from "@opencode-ai/core/util/log"
@@ -45,15 +44,11 @@ export function getReleaseType(current: string, latest: string): ReleaseType {
   return "patch"
 }
 
-export const Info = z
-  .object({
-    version: z.string(),
-    latest: z.string(),
-  })
-  .meta({
-    ref: "InstallationInfo",
-  })
-export type Info = z.infer<typeof Info>
+export const Info = Schema.Struct({
+  version: Schema.String,
+  latest: Schema.String,
+}).annotate({ identifier: "InstallationInfo" })
+export type Info = Schema.Schema.Type<typeof Info>
 
 export const USER_AGENT = `opencode/${InstallationChannel}/${InstallationVersion}/${Flag.OPENCODE_CLIENT}`
 
diff --git a/packages/opencode/src/patch/index.ts b/packages/opencode/src/patch/index.ts
index fd5fff5625bd..3dfa6f2d06fd 100644
--- a/packages/opencode/src/patch/index.ts
+++ b/packages/opencode/src/patch/index.ts
@@ -1,4 +1,4 @@
-import z from "zod"
+import { Schema } from "effect"
 import * as path from "path"
 import * as fs from "fs/promises"
 import { readFileSync } from "fs"
@@ -7,12 +7,11 @@ import * as Bom from "../util/bom"
 
 const log = Log.create({ service: "patch" })
 
-// Schema definitions
-export const PatchSchema = z.object({
-  patchText: z.string().describe("The full patch text that describes all changes to be made"),
+export const PatchSchema = Schema.Struct({
+  patchText: Schema.String.annotate({ description: "The full patch text that describes all changes to be made" }),
 })
 
-export type PatchParams = z.infer<typeof PatchSchema>
+export type PatchParams = Schema.Schema.Type<typeof PatchSchema>
 
 // Core types matching the Rust implementation
 export interface ApplyPatchArgs {
diff --git a/packages/opencode/src/provider/transform.ts b/packages/opencode/src/provider/transform.ts
index bd778dacc53e..72ec881e7b55 100644
--- a/packages/opencode/src/provider/transform.ts
+++ b/packages/opencode/src/provider/transform.ts
@@ -1,7 +1,6 @@
 import type { ModelMessage, ToolResultPart } from "ai"
 import { mergeDeep, unique } from "remeda"
 import type { JSONSchema7 } from "@ai-sdk/provider"
-import type { JSONSchema } from "zod/v4/core"
 import type * as Provider from "./provider"
 import type * as ModelsDev from "./models"
 import { iife } from "@/util/iife"
@@ -1281,7 +1280,7 @@ export function maxOutputTokens(model: Provider.Model): number {
   return Math.min(model.limit.output, OUTPUT_TOKEN_MAX) || OUTPUT_TOKEN_MAX
 }
 
-export function schema(model: Provider.Model, schema: JSONSchema.BaseSchema | JSONSchema7): JSONSchema7 {
+export function schema(model: Provider.Model, schema: JSONSchema7): JSONSchema7 {
   /*
   if (["openai", "azure"].includes(providerID)) {
     if (schema.type === "object" && schema.properties) {
@@ -1312,7 +1311,10 @@ export function schema(model: Provider.Model, schema: JSONSchema.BaseSchema | JS
       return result
     }
 
-    schema = sanitizeMoonshot(schema) as JSONSchema.BaseSchema | JSONSchema7
+    const sanitized = sanitizeMoonshot(schema)
+    if (typeof sanitized === "object" && sanitized !== null && !Array.isArray(sanitized)) {
+      schema = sanitized
+    }
   }
 
   // Convert integer enums to string enums for Google/Gemini
@@ -1394,7 +1396,7 @@ export function schema(model: Provider.Model, schema: JSONSchema.BaseSchema | JS
     schema = sanitizeGemini(schema)
   }
 
-  return schema as JSONSchema7
+  return schema
 }
 
 export * as ProviderTransform from "./transform"