perf: fix O(n²) allocation in jsonSchemaToZod required field handling

[ctonneslan]

Summary

Fixes two issues in jsonSchemaToZod required field handling:

1. O(n²) object allocation: The reduce with spread operator ({ ...acc, [field]: true }) copies the entire accumulator on every iteration. Replaced with a for...of loop that mutates a single object in O(n).

2. Redundant type guard: Array.isArray(schema.required) is unnecessary since schema.required is already typed as string[] in the JsonSchemaProperty interface. The truthiness check alone is sufficient.

Before

if (schema.required && Array.isArray(schema.required)) {
  const requiredFields = schema.required.reduce<Record<string, true>>(
    (acc, field) => ({ ...acc, [field]: true }),
    {},
  );

After

if (schema.required) {
  const requiredFields: Record<string, true> = {};
  for (const field of schema.required) {
    requiredFields[field] = true;
  }

Fixes #1773

---

Summary by cubic

Improve performance of required-field handling in jsonSchemaToZod by replacing the O(n²) reduce/spread pattern with an O(n) loop to cut allocations on large schemas. Also remove the redundant Array.isArray(schema.required) check since schema.required is typed as string[].

^{Written for commit 332c4fb. Summary will update on new commits. Review in cubic}

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[greptile-apps]

Greptile Summary

This PR makes a focused, correct performance optimization to jsonSchemaToZod in packages/core/lib/utils.ts. It replaces the O(n²) reduce + object spread pattern used to build the requiredFields lookup map with a simple O(n) for...of mutation loop, and removes the now-redundant Array.isArray(schema.required) guard (the JsonSchemaProperty interface already types required as string[]).

Key points:

• The functional behavior is fully preserved — the for...of loop produces the same Record<string, true> map fed into .partial().required(requiredFields)
• The empty-array edge case (schema.required: []) is handled identically: the truthiness check still passes, the loop runs zero iterations, and .partial().required({}) is called, making all fields optional — consistent with JSON Schema semantics
• The Array.isArray guard previously provided an implicit runtime safety net for callers passing non-array values; removing it is safe within this typed codebase, since all call sites are statically typed

Confidence Score: 5/5

• This PR is safe to merge — it's a correct, well-scoped performance optimization with no behavioral changes.
• The change is minimal (5 lines replaced by 5 lines), logically equivalent, and backed by correct reasoning about the TypeScript type system. No new code paths are introduced, and the edge cases (empty array, undefined) are handled identically to before.
• No files require special attention.

Important Files Changed

Filename	Overview
packages/core/lib/utils.ts	Replaces O(n²) reduce+spread with an O(n) for...of mutation loop, and removes the now-redundant Array.isArray guard on schema.required. Logic and behavior are preserved correctly.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A["jsonSchemaToZod(schema)"] --> B{schema.type === 'object'?}
    B -- No --> C[Handle other types]
    B -- Yes --> D{schema.properties?}
    D -- No --> E["return z.object({})"]
    D -- Yes --> F["Build shape via for...in loop\nO(n)"]
    F --> G["zodObject = z.object(shape)"]
    G --> H{schema.required?}
    H -- No --> J{schema.description?}
    H -- Yes --> I["Build requiredFields via for...of loop\nO(n) — no spread allocation"]
    I --> K["zodObject = zodObject.partial().required(requiredFields)"]
    K --> J
    J -- No --> L["return zodObject"]
    J -- Yes --> M["zodObject = zodObject.describe(description)"]
    M --> L

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[cubic-dev-ai]

No issues found across 1 file

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

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