Fix handling of checkbox inputs and optional arrays in UI

[madhav165]

🐛 Bug-fix PR

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📌 Summary

Form field generation for array types was incomplete and inconsistent:

1. Boolean arrays — Unchecked checkboxes sent no value (missing "false").
2. Array naming — Some inputs used key while others used key[].
3. Union schemas — Fields defined as anyOf: [ { type:"array" }, { type:"null" } ] (nullable arrays) were not recognized as arrays, causing the UI to render incorrectly and hide the Add items button.

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🔁 Reproduction Steps

1. Define a schema with:
   • items.type = boolean (boolean array).
   • OR anyOf: [ { type:"array", items:{...} }, { type:"null" } ] (nullable array).
2. Open the tool-test modal.
3. Observe:
   • Boolean arrays: unchecked boxes do not send "false".
   • Nullable arrays: UI fails to show as an array, no Add items button.

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🐞 Root Cause

• Only a visible <input type="checkbox"> was rendered for booleans → unchecked state omitted.
• Array field names were inconsistent (key vs key[]).
• Branching relied on prop.type === "array" only, so anyOf/oneOf unions with null were missed.

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💡 Fix Description

• Boolean array fix:
  • Added a hidden <input type="hidden" value="false"> for every boolean array item.
  • Disabled when checkbox is checked.
  • Guarantees "false" is submitted when unchecked.
• Unified naming: All array inputs now consistently use keyValidation.value + "[]".
• Input creation cleanup: Directly create the correct input type (number, boolean, text) instead of mutating a single element.
• Union schema support:
  • Added detection for arrays inside anyOf / oneOf alongside null.
  • Correctly handles schemas like anyOf: [ {type:"array"}, {type:"null"} ].
  • Renders UI as array with an Add items button, starting empty if default is null.
• Prevent double append: Boolean array inputs already append checkbox + hidden, so skip re-append.

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🧪 Verification

Check	Command	Status
Lint suite	make lint	✅
Unit tests	make test	✅
Manual regression - Boolean arrays	Unchecked boxes correctly submit "false"	✅
Manual regression - Number/text arrays	Values submit correctly	✅
Manual regression - Nullable arrays	Schema with anyOf: [array, null] renders with Add items button and submits properly	✅

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📐 MCP Compliance (if relevant)

• No breaking change to MCP clients

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✅ Checklist

• Code formatted (make black isort pre-commit)
• No secrets/credentials committed

[crivetimihai]

Likely fixed in latest, please re-open a new PR.