Roblox Platform Reference (house stack)

Overview

This is the platform theory a mid-level engineer without Roblox background needs, scoped to what has actually bitten this studio's projects. Every claim is grounded in the house stack (the conventions shared across firebit game repos) or a named source; when the platform surprises you, check here before inventing a fix. Where a fact is project-specific (a flag value, a product name, a line number), this file gives you the one-liner to verify it in the current project rather than a stale answer.

When to use / when NOT to use

Use when:

• Rotations or bases come out mirrored/flipped, or you're writing any CFrame math.
• A client-side handler sees a tagged instance but its children/parts are nil.
• You're touching profile load/save, purchases, receipts, or subscriptions.
• luau-lsp rejects code that "looks fine" (optional narrowing, iteration types).
• You need economy rationale (session vs persistent currency, discovery weighting).
• You need exact Roblox API signatures → follow the brain protocol in section 8.