undo migration to zod 4

Author: charleslien

backend/package.json

@@ -31,23 +31,23 @@
     "@codebuff/internal": "workspace:*",
     "@google-cloud/vertexai": "1.10.0",
     "@google/generative-ai": "0.24.1",
-    "@jitl/quickjs-wasmfile-release-sync": "0.31.0",
     "ai": "4.3.16",
     "cors": "^2.8.5",
     "diff": "5.2.0",
     "dotenv": "16.4.5",
     "express": "4.19.2",
     "gpt-tokenizer": "2.8.1",
     "ignore": "5.3.2",
+    "@jitl/quickjs-wasmfile-release-sync": "0.31.0",
+    "quickjs-emscripten-core": "0.31.0",
     "lodash": "*",
     "openai": "^4.78.1",
     "pino": "9.4.0",
     "postgres": "3.4.4",
     "posthog-node": "^4.14.0",
-    "quickjs-emscripten-core": "0.31.0",
     "ts-pattern": "5.3.1",
     "ws": "8.18.0",
-    "zod": "4.0.0",
+    "zod": "3.25.67",
     "zod-from-json-schema": "0.4.2"
   },
   "devDependencies": {

backend/src/api/org.ts

@@ -55,7 +55,7 @@ async function isRepoCoveredHandler(
     if (error instanceof z.ZodError) {
       return res
         .status(400)
-        .json({ error: 'Invalid request body', issues: error.issues })
+        .json({ error: 'Invalid request body', issues: error.errors })
     }
     next(error)
     return

backend/src/api/usage.ts

@@ -98,7 +98,7 @@ async function usageHandler(
     if (error instanceof z.ZodError) {
       return res
         .status(400)
-        .json({ message: 'Invalid request body', issues: error.issues })
+        .json({ message: 'Invalid request body', issues: error.errors })
     }
     next(error)
     return

backend/src/llm-apis/vercel-ai-sdk/ai-sdk.ts

@@ -270,7 +270,7 @@ export const promptAiSdk = async function (
 // Copied over exactly from promptAiSdk but with a schema
 export const promptAiSdkStructured = async function <T>(options: {
   messages: CodebuffMessage[]
-  schema: z.ZodType<T>
+  schema: z.ZodType<T, z.ZodTypeDef, any>
   clientSessionId: string
   fingerprintId: string
   userInputId: string

backend/src/system-prompt/prompts.ts

@@ -3,14 +3,14 @@ import {
   codebuffConfigFile,
   CodebuffConfigSchema,
 } from '@codebuff/common/json-config/constants'
+import { stringifySchema } from '@codebuff/common/json-config/stringify-schema'
 import {
   flattenTree,
   getLastReadFilePaths,
 } from '@codebuff/common/project-file-tree'
 import { createMarkdownFileBlock } from '@codebuff/common/util/file'
 import { truncateString } from '@codebuff/common/util/string'
 import { closeXml } from '@codebuff/common/util/xml'
-import { schemaToJsonStr } from '@codebuff/common/util/zod-schema'
 
 import { truncateFileTreeBasedOnTokenBudget } from './truncate-file-tree'
 
@@ -23,7 +23,7 @@ export const configSchemaPrompt = `
 
 The following describes the structure of the \`./${codebuffConfigFile}\` configuration file that users might have in their project root. You can use this to understand user settings if they mention them.
 
-${schemaToJsonStr(CodebuffConfigSchema)}
+${stringifySchema(CodebuffConfigSchema)}
 
 ## Background Processes
 

backend/src/templates/agents/archive/dry-run.ts

@@ -1,5 +1,5 @@
 import { AGENT_PERSONAS } from '@codebuff/common/constants/agents'
-import z from 'zod'
+import z from 'zod/v4'
 
 import { PLACEHOLDER } from '../../types'
 

backend/src/templates/agents/ask.ts

@@ -1,6 +1,6 @@
 import { AGENT_PERSONAS } from '@codebuff/common/constants/agents'
 import { AgentTemplateTypes } from '@codebuff/common/types/session-state'
-import z from 'zod'
+import z from 'zod/v4'
 
 import {
   askAgentAgentStepPrompt,

backend/src/templates/agents/base.ts

@@ -1,6 +1,6 @@
 import { AGENT_PERSONAS } from '@codebuff/common/constants/agents'
 import { AgentTemplateTypes } from '@codebuff/common/types/session-state'
-import z from 'zod'
+import z from 'zod/v4'
 
 import {
   baseAgentAgentStepPrompt,

backend/src/templates/agents/file-explorer.ts

@@ -1,5 +1,5 @@
 import { AgentTemplateTypes } from '@codebuff/common/types/session-state'
-import { z } from 'zod'
+import { z } from 'zod/v4'
 
 import type { AgentTemplate } from '../types'
 

backend/src/templates/agents/file-picker.ts

@@ -1,5 +1,5 @@
 import { AGENT_PERSONAS } from '@codebuff/common/constants/agents'
-import z from 'zod'
+import z from 'zod/v4'
 
 import { PLACEHOLDER } from '../types'