refactor(codemode): split interpreter and stdlib (#35572)

packages/codemode/codemode.md

@@ -153,6 +153,12 @@ current omissions to implement, not intentional product boundaries.
       shims. Consider `Promise.any` in the same pass.
 - [ ] Support async iteration and `for await...of`. Define behavior first for the runtime's supported promise and
       collection values, then extend it to bounded host streams when a stream boundary exists.
+- [ ] Support callback-bearing standard-library variants that models commonly generate: the mapper argument to
+      `Array.from(...)` and replacers for `JSON.stringify(...)`, including Effect-aware callbacks where needed.
+- [ ] Close basic `Object` parity gaps: let `Object.values`/`Object.entries` accept arrays, make `Object.assign` validate
+      and mutate its target, add `Object.is`, and let `Object.fromEntries` consume every supported iterable.
+- [ ] Add deterministic modern collection conveniences where they improve orchestration: `Object.groupBy`, Set
+      composition methods, and `Array.prototype.toSpliced`.
 - [ ] Complete the deterministic `Math` surface beyond the current arithmetic, rounding, root, power, and logarithm
       helpers. Decide separately whether nondeterministic `Math.random` belongs in the runtime.
 - [ ] Refine diagnostics so user throws, expected tool failures, unexpected host/tool defects, and genuine interpreter

packages/codemode/src/interpreter/model.ts

@@ -0,0 +1,200 @@
+import type { SafeObject } from "../tool-runtime.js"
+import type { SandboxURL } from "../values.js"
+
+export type SourcePosition = {
+  line: number
+  column: number
+}
+
+export type SourceLocation = {
+  start: SourcePosition
+  end: SourcePosition
+}
+
+export type AstNode = {
+  type: string
+  loc?: SourceLocation
+  [key: string]: unknown
+}
+
+export type ProgramNode = AstNode & {
+  type: "Program"
+  body: Array<AstNode>
+}
+
+export type Binding = {
+  mutable: boolean
+  value: unknown
+  initialized?: boolean
+}
+
+export type StatementResult =
+  | { kind: "none" }
+  | { kind: "value"; value: unknown }
+  | { kind: "return"; value: unknown }
+  | { kind: "break" }
+  | { kind: "continue" }
+
+export type MemberReference = {
+  target: SafeObject | Array<unknown> | SandboxURL
+  key: string | number
+}
+
+export class CodeModeFunction {
+  constructor(
+    readonly parameters: ReadonlyArray<AstNode>,
+    readonly body: AstNode,
+    readonly capturedScopes: ReadonlyArray<Map<string, Binding>>,
+  ) {}
+}
+
+export class IntrinsicReference {
+  constructor(
+    readonly receiver: unknown,
+    readonly name: string,
+  ) {}
+}
+
+export class ComputedValue {
+  constructor(readonly value: unknown) {}
+}
+
+export class PromiseNamespace {}
+
+export type PromiseMethodName = "all" | "allSettled" | "race" | "resolve" | "reject"
+
+export class PromiseMethodReference {
+  constructor(readonly name: PromiseMethodName) {}
+}
+
+export type GlobalNamespaceName =
+  | "Object"
+  | "Math"
+  | "JSON"
+  | "Array"
+  | "console"
+  | "Date"
+  | "RegExp"
+  | "Map"
+  | "Set"
+  | "URL"
+  | "URLSearchParams"
+
+export class GlobalNamespace {
+  constructor(readonly name: GlobalNamespaceName) {}
+}
+
+export class GlobalMethodReference {
+  constructor(
+    readonly namespace: GlobalNamespaceName | "Number" | "String",
+    readonly name: string,
+  ) {}
+}
+
+export class CoercionFunction {
+  constructor(readonly name: "Number" | "String" | "Boolean" | "parseInt" | "parseFloat") {}
+}
+
+export class UriFunction {
+  constructor(readonly name: "encodeURI" | "encodeURIComponent" | "decodeURI" | "decodeURIComponent") {}
+}
+
+export class ProgramThrow {
+  constructor(readonly value: unknown) {}
+}
+
+export class ErrorConstructorReference {
+  constructor(readonly name: string) {}
+}
+
+export type DiagnosticKind =
+  | "ParseError"
+  | "UnsupportedSyntax"
+  | "UnknownTool"
+  | "InvalidToolInput"
+  | "InvalidToolOutput"
+  | "InvalidDataValue"
+  | "ToolCallLimitExceeded"
+  | "TimeoutExceeded"
+  | "ToolFailure"
+  | "ExecutionFailure"
+
+export const OptionalShortCircuit: unique symbol = Symbol("codemode.optional-short-circuit")
+
+export const supportedSyntaxMessage =
+  "Supported orchestration syntax: tools.* calls (they return promises - resolve them with await), data literals, destructuring, optional chaining, template literals, conditionals, switch, loops (incl. for...of and for...in over object/array/tools keys), arrow functions, spread, try/catch, array methods (map/filter/find/findIndex/some/every/reduce/flatMap/forEach/sort/slice/concat/indexOf/lastIndexOf/at/flat/reverse/includes/join), string methods (incl. match/matchAll/replace/split with regular expressions), Date/RegExp/Map/Set/URL/URLSearchParams, URI encoding helpers, Object/Math/JSON helpers, captured console.log/warn/error/dir/table, and Promise.all/allSettled/race/resolve/reject over arrays mixing promises and plain values for parallel tool calls (promise chaining with .then/.catch is not supported - use await with try/catch)."
+
+export class InterpreterRuntimeError extends Error {
+  readonly node?: AstNode
+  errorName: string = "Error"
+
+  constructor(
+    message: string,
+    node?: AstNode,
+    readonly kind: DiagnosticKind = "ExecutionFailure",
+    readonly suggestions?: ReadonlyArray<string>,
+  ) {
+    super(message)
+    this.name = "InterpreterRuntimeError"
+    if (node) this.node = node
+  }
+
+  as(errorName: string): this {
+    this.errorName = errorName
+    return this
+  }
+}
+
+export const unsupportedSyntax = (kind: string, node: AstNode): InterpreterRuntimeError =>
+  new InterpreterRuntimeError(
+    `Syntax '${kind}' is not supported in CodeMode. ${supportedSyntaxMessage}`,
+    node,
+    "UnsupportedSyntax",
+    [supportedSyntaxMessage],
+  )
+
+export const isRecord = (value: unknown): value is Record<string, unknown> => typeof value === "object" && value !== null
+
+export const asNode = (value: unknown, context: string): AstNode => {
+  if (!isRecord(value) || typeof value.type !== "string") {
+    throw new InterpreterRuntimeError(`Invalid AST node while reading ${context}.`)
+  }
+  return value as AstNode
+}
+
+export const getArray = (node: AstNode, key: string): Array<unknown> => {
+  const value = node[key]
+  if (!Array.isArray(value)) throw new InterpreterRuntimeError(`Expected '${key}' to be an array.`, node)
+  return value
+}
+
+export const getString = (node: AstNode, key: string): string => {
+  const value = node[key]
+  if (typeof value !== "string") throw new InterpreterRuntimeError(`Expected '${key}' to be a string.`, node)
+  return value
+}
+
+export const getBoolean = (node: AstNode, key: string): boolean => {
+  const value = node[key]
+  if (typeof value !== "boolean") throw new InterpreterRuntimeError(`Expected '${key}' to be a boolean.`, node)
+  return value
+}
+
+export const getOptionalNode = (node: AstNode, key: string): AstNode | undefined => {
+  const value = node[key]
+  if (value === undefined || value === null) return undefined
+  return asNode(value, key)
+}
+
+export const getNode = (node: AstNode, key: string): AstNode => asNode(node[key], key)
+
+export const sourceLocation = (node: AstNode): { readonly line: number; readonly column: number } => ({
+  line: Math.max(1, (node.loc?.start.line ?? 2) - 1),
+  column: Math.max(1, (node.loc?.start.column ?? 4) - 3),
+})
+
+export const formatLocation = (node?: AstNode): string => {
+  if (!node?.loc) return ""
+  const location = sourceLocation(node)
+  return ` (line ${location.line}, col ${location.column})`
+}

packages/codemode/src/stdlib/collections.ts

@@ -0,0 +1,51 @@
+export const arrayMethods = new Set([
+  "map",
+  "filter",
+  "find",
+  "findIndex",
+  "findLast",
+  "findLastIndex",
+  "some",
+  "every",
+  "includes",
+  "join",
+  "reduce",
+  "reduceRight",
+  "flatMap",
+  "forEach",
+  "sort",
+  "toSorted",
+  "slice",
+  "concat",
+  "indexOf",
+  "lastIndexOf",
+  "at",
+  "flat",
+  "reverse",
+  "toReversed",
+  "with",
+  "push",
+  "pop",
+  "shift",
+  "unshift",
+  "splice",
+  "fill",
+  "copyWithin",
+  "keys",
+  "values",
+  "entries",
+])
+
+export const mapMethods = new Set(["get", "set", "has", "delete", "clear", "forEach", "keys", "values", "entries"])
+
+export const setMethods = new Set(["add", "has", "delete", "clear", "forEach", "keys", "values", "entries"])
+
+export const spreadItems = (value: unknown): Array<unknown> | undefined => {
+  if (Array.isArray(value)) return value
+  if (typeof value === "string") return Array.from(value)
+  if (value instanceof SandboxMap) return Array.from(value.map.entries(), ([key, item]) => [key, item])
+  if (value instanceof SandboxSet) return Array.from(value.set.values())
+  if (value instanceof SandboxURLSearchParams) return Array.from(value.params.entries(), ([key, item]) => [key, item])
+  return undefined
+}
+import { SandboxMap, SandboxSet, SandboxURLSearchParams } from "../values.js"

packages/codemode/src/stdlib/console.ts

@@ -0,0 +1,4 @@
+export const consoleMethods = new Set(["log", "info", "debug", "warn", "error", "dir", "table"])
+
+/** Console formatting recursion ceiling; deeper values render as "...". */
+export const MAX_CONSOLE_DEPTH = 32

packages/codemode/src/stdlib/date.ts

@@ -0,0 +1,94 @@
+export const dateMethods = new Set([
+  "getTime",
+  "valueOf",
+  "toISOString",
+  "toJSON",
+  "toString",
+  "getFullYear",
+  "getMonth",
+  "getDate",
+  "getDay",
+  "getHours",
+  "getMinutes",
+  "getSeconds",
+  "getMilliseconds",
+  "getUTCFullYear",
+  "getUTCMonth",
+  "getUTCDate",
+  "getUTCDay",
+  "getUTCHours",
+  "getUTCMinutes",
+  "getUTCSeconds",
+  "getUTCMilliseconds",
+  "getTimezoneOffset",
+])
+
+export const dateStatics = new Set(["now", "parse", "UTC"])
+
+export const invokeDateStatic = (name: string, args: Array<unknown>, node: AstNode): number => {
+  switch (name) {
+    case "now":
+      return Date.now()
+    case "parse":
+      return Date.parse(coerceToString(args[0]))
+    case "UTC":
+      return Date.UTC(...(args.map((arg) => coerceToNumber(arg)) as Parameters<typeof Date.UTC>))
+    default:
+      throw new InterpreterRuntimeError(`Date.${name} is not available in CodeMode.`, node)
+  }
+}
+
+export const invokeDateMethod = (value: SandboxDate, name: string, node: AstNode): unknown => {
+  const hosted = new Date(value.time)
+  switch (name) {
+    case "getTime":
+    case "valueOf":
+      return value.time
+    case "toISOString":
+      if (!Number.isFinite(value.time)) throw new InterpreterRuntimeError("Invalid time value.", node)
+      return hosted.toISOString()
+    case "toJSON":
+      return Number.isFinite(value.time) ? hosted.toISOString() : null
+    case "toString":
+      return coerceToString(value)
+    case "getFullYear":
+      return hosted.getFullYear()
+    case "getMonth":
+      return hosted.getMonth()
+    case "getDate":
+      return hosted.getDate()
+    case "getDay":
+      return hosted.getDay()
+    case "getHours":
+      return hosted.getHours()
+    case "getMinutes":
+      return hosted.getMinutes()
+    case "getSeconds":
+      return hosted.getSeconds()
+    case "getMilliseconds":
+      return hosted.getMilliseconds()
+    case "getUTCFullYear":
+      return hosted.getUTCFullYear()
+    case "getUTCMonth":
+      return hosted.getUTCMonth()
+    case "getUTCDate":
+      return hosted.getUTCDate()
+    case "getUTCDay":
+      return hosted.getUTCDay()
+    case "getUTCHours":
+      return hosted.getUTCHours()
+    case "getUTCMinutes":
+      return hosted.getUTCMinutes()
+    case "getUTCSeconds":
+      return hosted.getUTCSeconds()
+    case "getUTCMilliseconds":
+      return hosted.getUTCMilliseconds()
+    case "getTimezoneOffset":
+      return hosted.getTimezoneOffset()
+    default:
+      throw new InterpreterRuntimeError(`Date method '${name}' is not available in CodeMode.`, node)
+  }
+}
+import { type AstNode, InterpreterRuntimeError } from "../interpreter/model.js"
+import { SandboxDate } from "../values.js"
+import { coerceToNumber, coerceToString } from "./value.js"

packages/codemode/src/stdlib/json.ts

@@ -0,0 +1,42 @@
+import {
+  type AstNode,
+  CodeModeFunction,
+  InterpreterRuntimeError,
+  supportedSyntaxMessage,
+} from "../interpreter/model.js"
+import { copyIn, copyOut } from "../tool-runtime.js"
+
+export const jsonStatics = new Set(["stringify", "parse"])
+
+export const invokeJsonMethod = (name: string, args: Array<unknown>, node: AstNode): unknown => {
+  if (!jsonStatics.has(name)) throw new InterpreterRuntimeError(`JSON.${name} is not available in CodeMode.`, node)
+  switch (name) {
+    case "stringify": {
+      const replacer = args[1]
+      if (Array.isArray(replacer) || replacer instanceof CodeModeFunction) {
+        throw new InterpreterRuntimeError(
+          "JSON.stringify replacers are not supported in CodeMode.",
+          node,
+          "UnsupportedSyntax",
+          [supportedSyntaxMessage],
+        )
+      }
+      const space = args[2]
+      const indent = typeof space === "number" || typeof space === "string" ? space : undefined
+      return JSON.stringify(copyOut(copyIn(args[0], "JSON.stringify value")), null, indent)
+    }
+    case "parse": {
+      const text = args[0]
+      if (typeof text !== "string") throw new InterpreterRuntimeError("JSON.parse expects a string.", node)
+      try {
+        return copyIn(JSON.parse(text), "JSON.parse result")
+      } catch (error) {
+        throw new InterpreterRuntimeError(
+          `JSON.parse received invalid JSON: ${error instanceof Error ? error.message : String(error)}`,
+          node,
+        ).as("SyntaxError")
+      }
+    }
+  }
+  throw new InterpreterRuntimeError(`JSON.${name} is not available in CodeMode.`, node)
+}

packages/codemode/src/stdlib/math.ts

@@ -0,0 +1,65 @@
+export const mathConstants = new Set(["PI", "E", "LN2", "LN10", "LOG2E", "LOG10E", "SQRT2", "SQRT1_2"])
+
+export const mathMethods = new Set([
+  "max",
+  "min",
+  "abs",
+  "floor",
+  "ceil",
+  "round",
+  "trunc",
+  "sign",
+  "sqrt",
+  "cbrt",
+  "pow",
+  "hypot",
+  "log",
+  "log2",
+  "log10",
+  "exp",
+])
+
+export const invokeMathMethod = (name: string, args: Array<unknown>, node: AstNode): number => {
+  if (!mathMethods.has(name)) throw new InterpreterRuntimeError(`Math.${name} is not available in CodeMode.`, node)
+  const nums = args.map((arg) => {
+    if (typeof arg !== "number") throw new InterpreterRuntimeError(`Math.${name} expects number arguments.`, node)
+    return arg
+  })
+  const [a = Number.NaN, b = Number.NaN] = nums
+  switch (name) {
+    case "max":
+      return Math.max(...nums)
+    case "min":
+      return Math.min(...nums)
+    case "abs":
+      return Math.abs(a)
+    case "floor":
+      return Math.floor(a)
+    case "ceil":
+      return Math.ceil(a)
+    case "round":
+      return Math.round(a)
+    case "trunc":
+      return Math.trunc(a)
+    case "sign":
+      return Math.sign(a)
+    case "sqrt":
+      return Math.sqrt(a)
+    case "cbrt":
+      return Math.cbrt(a)
+    case "pow":
+      return Math.pow(a, b)
+    case "hypot":
+      return Math.hypot(...nums)
+    case "log":
+      return Math.log(a)
+    case "log2":
+      return Math.log2(a)
+    case "log10":
+      return Math.log10(a)
+    case "exp":
+      return Math.exp(a)
+  }
+  throw new InterpreterRuntimeError(`Math.${name} is not available in CodeMode.`, node)
+}
+import { type AstNode, InterpreterRuntimeError } from "../interpreter/model.js"

packages/codemode/src/stdlib/number.ts

@@ -0,0 +1,66 @@
+export const numberMethods = new Set(["toFixed", "toPrecision", "toExponential", "toString"])
+
+export const numberConstants = new Set(["MAX_SAFE_INTEGER", "MIN_SAFE_INTEGER", "MAX_VALUE", "MIN_VALUE", "EPSILON"])
+
+export const numberStatics = new Set(["isInteger", "isFinite", "isNaN", "isSafeInteger", "parseInt", "parseFloat"])
+
+export const invokeNumberMethod = (value: number, name: string, args: Array<unknown>, node: AstNode): unknown => {
+  const optNum = (index: number): number | undefined => {
+    const arg = args[index]
+    if (arg === undefined) return undefined
+    if (typeof arg !== "number") throw new InterpreterRuntimeError(`Number.${name} expects a number argument.`, node)
+    return arg
+  }
+  let result: unknown
+  switch (name) {
+    case "toFixed":
+      result = value.toFixed(optNum(0))
+      break
+    case "toExponential":
+      result = value.toExponential(optNum(0))
+      break
+    case "toPrecision": {
+      const digits = optNum(0)
+      result = digits === undefined ? value.toString() : value.toPrecision(digits)
+      break
+    }
+    case "toString": {
+      const radix = optNum(0)
+      if (radix !== undefined && (radix < 2 || radix > 36)) {
+        throw new InterpreterRuntimeError("Number.toString radix must be between 2 and 36.", node)
+      }
+      result = value.toString(radix)
+      break
+    }
+    default:
+      throw new InterpreterRuntimeError(`Number method '${name}' is not available in CodeMode.`, node)
+  }
+  return boundedData(result, `Number.${name} result`)
+}
+
+export const invokeNumberStatic = (name: string, args: Array<unknown>, node: AstNode): unknown => {
+  const value = args[0]
+  switch (name) {
+    case "isInteger":
+      return Number.isInteger(value)
+    case "isFinite":
+      return Number.isFinite(value)
+    case "isNaN":
+      return Number.isNaN(value)
+    case "isSafeInteger":
+      return Number.isSafeInteger(value)
+    case "parseInt": {
+      const radix = args[1]
+      if (radix !== undefined && typeof radix !== "number") {
+        throw new InterpreterRuntimeError("Number.parseInt expects a numeric radix.", node)
+      }
+      return parseInt(coerceToString(value), radix)
+    }
+    case "parseFloat":
+      return parseFloat(coerceToString(value))
+    default:
+      throw new InterpreterRuntimeError(`Number.${name} is not available in CodeMode.`, node)
+  }
+}
+import { type AstNode, InterpreterRuntimeError } from "../interpreter/model.js"
+import { boundedData, coerceToString } from "./value.js"

packages/codemode/src/stdlib/object.ts

@@ -0,0 +1,77 @@
+import { type AstNode, InterpreterRuntimeError } from "../interpreter/model.js"
+import { isBlockedMember } from "../tool-runtime.js"
+import { isSandboxValue, SandboxMap, SandboxURLSearchParams } from "../values.js"
+import { boundedData, coerceToString } from "./value.js"
+
+export const objectStatics = new Set(["keys", "values", "entries", "hasOwn", "assign", "fromEntries"])
+
+export const invokeObjectMethod = (name: string, args: Array<unknown>, node: AstNode): unknown => {
+  if (!objectStatics.has(name)) throw new InterpreterRuntimeError(`Object.${name} is not available in CodeMode.`, node)
+  const requireObject = (): Record<string, unknown> => {
+    const value = boundedData(args[0], `Object.${name} input`)
+    if (isSandboxValue(value)) return {}
+    if (value === null || typeof value !== "object" || Array.isArray(value)) {
+      throw new InterpreterRuntimeError(`Object.${name} expects a data object.`, node)
+    }
+    return value as Record<string, unknown>
+  }
+  const guardedSet = (out: Record<string, unknown>, key: string, item: unknown): void => {
+    if (isBlockedMember(key)) throw new InterpreterRuntimeError(`Property '${key}' is not available in CodeMode.`, node)
+    out[key] = item
+  }
+  switch (name) {
+    case "keys": {
+      const value = boundedData(args[0], "Object.keys input")
+      if (isSandboxValue(value)) return []
+      if (Array.isArray(value)) return Object.keys(value)
+      if (value === null || typeof value !== "object") {
+        throw new InterpreterRuntimeError("Object.keys expects a data object or array.", node)
+      }
+      return Object.keys(value)
+    }
+    case "values":
+      return Object.values(requireObject())
+    case "entries":
+      return Object.entries(requireObject()).map(([key, item]) => [key, item])
+    case "hasOwn":
+      return Object.hasOwn(requireObject(), String(args[1]))
+    case "assign": {
+      const out: Record<string, unknown> = Object.create(null)
+      for (const source of args) {
+        if (source === null || source === undefined) continue
+        const value = boundedData(source, "Object.assign input")
+        if (isSandboxValue(value)) continue
+        if (value === null || typeof value !== "object" || Array.isArray(value)) {
+          throw new InterpreterRuntimeError("Object.assign expects data objects.", node)
+        }
+        for (const [key, item] of Object.entries(value)) guardedSet(out, key, item)
+      }
+      return out
+    }
+    case "fromEntries": {
+      if (args[0] instanceof SandboxMap) {
+        const out: Record<string, unknown> = Object.create(null)
+        for (const [key, item] of args[0].map.entries()) guardedSet(out, coerceToString(key), item)
+        return out
+      }
+      if (args[0] instanceof SandboxURLSearchParams) {
+        const out: Record<string, unknown> = Object.create(null)
+        for (const [key, value] of args[0].params.entries()) guardedSet(out, key, value)
+        return out
+      }
+      const pairs = boundedData(args[0], "Object.fromEntries input")
+      if (!Array.isArray(pairs)) {
+        throw new InterpreterRuntimeError("Object.fromEntries expects an array of [key, value] pairs.", node)
+      }
+      const out: Record<string, unknown> = Object.create(null)
+      for (const pair of pairs) {
+        if (!Array.isArray(pair)) {
+          throw new InterpreterRuntimeError("Object.fromEntries expects [key, value] pairs.", node)
+        }
+        guardedSet(out, String(pair[0]), pair[1])
+      }
+      return out
+    }
+  }
+  throw new InterpreterRuntimeError(`Object.${name} is not available in CodeMode.`, node)
+}

packages/codemode/src/stdlib/promise.ts

@@ -0,0 +1,6 @@
+import type { PromiseMethodName } from "../interpreter/model.js"
+
+export const promiseStatics = new Set<PromiseMethodName>(["all", "allSettled", "race", "resolve", "reject"])
+
+/** Maximum number of eagerly forked tool calls that may run concurrently. */
+export const TOOL_CALL_CONCURRENCY = 8

packages/codemode/src/stdlib/regexp.ts

@@ -0,0 +1,74 @@
+export const regexpMethods = new Set(["test", "exec", "toString"])
+
+export const regexpProperties = new Set([
+  "source",
+  "flags",
+  "lastIndex",
+  "global",
+  "ignoreCase",
+  "multiline",
+  "sticky",
+  "unicode",
+  "dotAll",
+])
+
+export const regexFailureReason = (error: unknown): string =>
+  (error instanceof Error ? error.message : String(error)).replace(/^Invalid regular expression:\s*/i, "")
+
+export const escapeRegexHint =
+  'To match special characters like ( ) [ ] { } + * ? . literally, escape them with a backslash (e.g. "\\\\(") or test for them with String.includes instead.'
+
+export const toHostRegex = (arg: unknown, method: string, node: AstNode, extraFlags = ""): RegExp => {
+  if (arg instanceof SandboxRegExp) return arg.regex
+  if (typeof arg === "string") {
+    try {
+      return new RegExp(arg, extraFlags)
+    } catch (error) {
+      throw new InterpreterRuntimeError(
+        `String.${method} received the string ${JSON.stringify(arg)}, which is not a valid regular expression pattern (${regexFailureReason(error)}). ${escapeRegexHint}`,
+        node,
+      ).as("SyntaxError")
+    }
+  }
+  throw new InterpreterRuntimeError(
+    `String.${method} expects a regular expression (a /pattern/flags literal or new RegExp(...)) or a string pattern, not ${arg === null ? "null" : typeof arg}.`,
+    node,
+  )
+}
+
+export const matchToValue = (match: RegExpMatchArray): Array<unknown> => {
+  const result: Array<unknown> = Array.from(match, (group) => group)
+  if (match.index !== undefined) (result as Record<string, unknown> & Array<unknown>).index = match.index
+  if (match.groups) {
+    const groups: SafeObject = Object.create(null) as SafeObject
+    for (const [key, group] of Object.entries(match.groups)) {
+      if (!isBlockedMember(key)) groups[key] = group
+    }
+    ;(result as Record<string, unknown> & Array<unknown>).groups = groups
+  }
+  return result
+}
+
+export const invokeRegExpMethod = (
+  value: SandboxRegExp,
+  name: string,
+  args: Array<unknown>,
+  node: AstNode,
+): unknown => {
+  switch (name) {
+    case "test":
+      return value.regex.test(coerceToString(args[0]))
+    case "exec": {
+      const matched = value.regex.exec(coerceToString(args[0]))
+      return matched === null ? null : matchToValue(matched)
+    }
+    case "toString":
+      return coerceToString(value)
+    default:
+      throw new InterpreterRuntimeError(`RegExp method '${name}' is not available in CodeMode.`, node)
+  }
+}
+import { type AstNode, InterpreterRuntimeError } from "../interpreter/model.js"
+import { isBlockedMember, type SafeObject } from "../tool-runtime.js"
+import { SandboxRegExp } from "../values.js"
+import { coerceToString } from "./value.js"

packages/codemode/src/stdlib/string.ts

@@ -0,0 +1,52 @@
+export const stringMethods = new Set([
+  "toLowerCase",
+  "toUpperCase",
+  "trim",
+  "trimStart",
+  "trimEnd",
+  "trimLeft",
+  "trimRight",
+  "split",
+  "slice",
+  "substring",
+  "substr",
+  "includes",
+  "startsWith",
+  "endsWith",
+  "indexOf",
+  "lastIndexOf",
+  "replace",
+  "replaceAll",
+  "repeat",
+  "padStart",
+  "padEnd",
+  "charAt",
+  "charCodeAt",
+  "codePointAt",
+  "at",
+  "concat",
+  "toString",
+  "match",
+  "matchAll",
+  "search",
+  "localeCompare",
+  "normalize",
+])
+
+export const stringStatics = new Set(["fromCharCode", "fromCodePoint"])
+
+export const invokeStringStatic = (name: string, args: Array<unknown>, node: AstNode): unknown => {
+  const codes = args.map((arg) => {
+    if (typeof arg !== "number") throw new InterpreterRuntimeError(`String.${name} expects number arguments.`, node)
+    return arg
+  })
+  switch (name) {
+    case "fromCharCode":
+      return String.fromCharCode(...codes)
+    case "fromCodePoint":
+      return String.fromCodePoint(...codes)
+    default:
+      throw new InterpreterRuntimeError(`String.${name} is not available in CodeMode.`, node)
+  }
+}
+import { type AstNode, InterpreterRuntimeError } from "../interpreter/model.js"

packages/codemode/src/stdlib/url.ts

@@ -0,0 +1,90 @@
+export const urlProperties = new Set([
+  "href",
+  "origin",
+  "protocol",
+  "username",
+  "password",
+  "host",
+  "hostname",
+  "port",
+  "pathname",
+  "search",
+  "hash",
+])
+
+export const urlWritableProperties = new Set([
+  "href",
+  "protocol",
+  "username",
+  "password",
+  "host",
+  "hostname",
+  "port",
+  "pathname",
+  "search",
+  "hash",
+])
+
+export const urlMethods = new Set(["toString", "toJSON"])
+export const urlStatics = new Set(["canParse", "parse"])
+export const urlSearchParamsMethods = new Set([
+  "append",
+  "delete",
+  "get",
+  "getAll",
+  "has",
+  "set",
+  "sort",
+  "forEach",
+  "keys",
+  "values",
+  "entries",
+  "toString",
+])
+
+export const uriArgument = (value: unknown, label: string): string => coerceToString(boundedData(value, label))
+
+export const invokeUriFunction = (ref: UriFunction, args: Array<unknown>, node: AstNode): string => {
+  const value = uriArgument(args[0], `${ref.name} input`)
+  try {
+    switch (ref.name) {
+      case "encodeURI":
+        return encodeURI(value)
+      case "encodeURIComponent":
+        return encodeURIComponent(value)
+      case "decodeURI":
+        return decodeURI(value)
+      case "decodeURIComponent":
+        return decodeURIComponent(value)
+    }
+  } catch (error) {
+    throw new InterpreterRuntimeError(
+      `${ref.name} received malformed URI data: ${error instanceof Error ? error.message : String(error)}`,
+      node,
+    ).as("URIError")
+  }
+}
+
+export const urlArgument = (value: unknown, label: string): string =>
+  value instanceof SandboxURL ? value.url.href : uriArgument(value, label)
+
+export const invokeURLStatic = (name: string, args: Array<unknown>, node: AstNode): unknown => {
+  if (!urlStatics.has(name)) throw new InterpreterRuntimeError(`URL.${name} is not available in CodeMode.`, node)
+  if (args.length === 0) throw new InterpreterRuntimeError(`URL.${name} requires a URL argument.`, node).as("TypeError")
+  const input = urlArgument(args[0], `URL.${name} input`)
+  const base = args[1] === undefined ? undefined : urlArgument(args[1], `URL.${name} base`)
+  try {
+    const url = new URL(input, base)
+    return name === "canParse" ? true : new SandboxURL(url)
+  } catch {
+    return name === "canParse" ? false : null
+  }
+}
+
+export const invokeURLMethod = (value: SandboxURL, name: string, node: AstNode): string => {
+  if (name === "toString" || name === "toJSON") return value.url.href
+  throw new InterpreterRuntimeError(`URL method '${name}' is not available in CodeMode.`, node)
+}
+import { type AstNode, InterpreterRuntimeError, UriFunction } from "../interpreter/model.js"
+import { SandboxURL } from "../values.js"
+import { boundedData, coerceToString } from "./value.js"

packages/codemode/src/stdlib/value.ts

@@ -0,0 +1,90 @@
+export const errorConstructors = new Set([
+  "Error",
+  "TypeError",
+  "RangeError",
+  "SyntaxError",
+  "ReferenceError",
+  "EvalError",
+  "URIError",
+])
+
+export const valueConstructors = new Set(["Date", "RegExp", "Map", "Set", "URL", "URLSearchParams"])
+
+export const compoundOperators = new Set(["+=", "-=", "*=", "/=", "%=", "**=", "&=", "|=", "^=", "<<=", ">>=", ">>>="])
+
+const ErrorBrand: unique symbol = Symbol("codemode.error")
+
+export const createErrorValue = (name: string, message: string): SafeObject => {
+  const value = Object.assign(Object.create(null) as SafeObject, { name, message })
+  Object.defineProperty(value, ErrorBrand, { value: name })
+  return value
+}
+
+export const errorBrandName = (value: unknown): string | undefined =>
+  value !== null && typeof value === "object"
+    ? ((value as Record<PropertyKey, unknown>)[ErrorBrand] as string | undefined)
+    : undefined
+
+export const boundedData = (value: unknown, label: string): unknown => copyIn(value, label, true)
+
+export const coerceToString = (value: unknown): string => {
+  if (value === null) return "null"
+  if (value === undefined) return "undefined"
+  if (value instanceof SandboxDate)
+    return Number.isFinite(value.time) ? new Date(value.time).toISOString() : "Invalid Date"
+  if (value instanceof SandboxRegExp) return `/${value.regex.source}/${value.regex.flags}`
+  if (value instanceof SandboxMap) return "[object Map]"
+  if (value instanceof SandboxSet) return "[object Set]"
+  if (value instanceof SandboxURL) return value.url.href
+  if (value instanceof SandboxURLSearchParams) return value.params.toString()
+  if (typeof value === "object") {
+    return Array.isArray(value)
+      ? value.map((item) => (item === null || item === undefined ? "" : coerceToString(item))).join(",")
+      : "[object Object]"
+  }
+  return String(value)
+}
+
+export const coerceToNumber = (value: unknown): number => {
+  if (value instanceof SandboxDate) return value.time
+  if (isSandboxValue(value)) return Number.NaN
+  return value !== null && typeof value === "object" && !Array.isArray(value) ? Number.NaN : Number(value)
+}
+
+export const invokeCoercion = (ref: CoercionFunction, args: Array<unknown>, node: AstNode): unknown => {
+  const raw = args[0]
+  if (isSandboxValue(raw)) {
+    if (ref.name === "Boolean") return true
+    if (ref.name === "Number") return coerceToNumber(raw)
+    if (ref.name === "String") return coerceToString(raw)
+    if (ref.name === "parseInt") return parseInt(coerceToString(raw))
+    return parseFloat(coerceToString(raw))
+  }
+  const value = boundedData(args[0], `${ref.name} input`)
+  if (ref.name === "Number") return coerceToNumber(value)
+  if (ref.name === "Boolean") return Boolean(value)
+  if (ref.name === "parseInt") {
+    const radix = args[1]
+    if (radix !== undefined && typeof radix !== "number") {
+      throw new InterpreterRuntimeError("parseInt expects a numeric radix.", node)
+    }
+    return parseInt(coerceToString(value), radix)
+  }
+  if (ref.name === "parseFloat") return parseFloat(coerceToString(value))
+  return coerceToString(value)
+}
+import {
+  type AstNode,
+  CoercionFunction,
+  InterpreterRuntimeError,
+} from "../interpreter/model.js"
+import { copyIn, type SafeObject } from "../tool-runtime.js"
+import {
+  isSandboxValue,
+  SandboxDate,
+  SandboxMap,
+  SandboxRegExp,
+  SandboxSet,
+  SandboxURL,
+  SandboxURLSearchParams,
+} from "../values.js"