fa-product-vertical-slice

name	fa-product-vertical-slice
description	Provides Stage 5 vertical-slice / MVP guidance for consumer one-off / in-app-purchase products - the spec stack (one-pager -> PRD/GDD -> monetization design doc as a binding instrumentation contract), MLP vs MVG with a designed purchase moment, a prototyping fidelity ladder, tech/billing spikes (StoreKit/Play Billing/Steamworks sandbox), server-authority and anti-cheat decisions, building analytics and IAP/entitlement rails first, and a shippable slice with one of every SKU type. Use to ship a lovable core loop with a live sandbox purchase and a clean reconciled funnel.
license	MIT

Gaia Product Vertical Slice

Scope and when to use

Use this skill to build the lovable core loop with the purchase moment designed in. Scope is one-off + IAP/IAG monetization; B2B seat-based SaaS is out of scope and an auto-renew model is red-lined unless an in-scope decision is recorded.

Use when:

• a validated bet needs a shippable-fidelity vertical slice
• billing, entitlement, and analytics rails must exist before content
• purchase intent must be testable against pre-committed thresholds

Do not use when:

• the bet has no money-on-the-line signal yet (run validation first)
• the slice is built and only needs production hardening

Required inputs

• the validated money model, confirmed price points, and concept brief
• the current unit-economics model version
• platform billing and analytics constraints

Owned outputs

• the spec stack: one-pager, PRD/GDD, and the binding monetization design doc
• a shippable-fidelity slice with one of every SKU type
• a sandbox purchase granting an entitlement and a clean reconciled funnel

Core workflow

1. Write the spec stack: one-pager -> PRD/GDD -> monetization design doc as a binding instrumentation contract.
2. Target an MLP (lovable) over a bare MVG; design the purchase moment INTO the loop and map the first-meaningful-purchase path.
3. Climb the prototyping fidelity ladder (paper -> clickable -> playable), killing cheap, high-uncertainty risk first and testing purchase intent even with fake money.
4. Run tech/billing spikes against StoreKit / Play Billing / Steamworks sandbox, covering restore and receipt/entitlement.
5. Decide server-authority vs client-trust plus anti-cheat/fraud posture.
6. Choose the engine / commerce / analytics stack.
7. Build analytics and IAP/entitlement rails FIRST: sandbox purchase, funnel events, entitlement that survives reinstall/restore, receipt validation, and ATT/consent.
8. Build the slice at shippable fidelity including one of every SKU type, against pre-committed success thresholds.

Rails-first gate

• The slice is not "done" without a sandbox purchase that grants an entitlement.
• The funnel must reconcile cleanly end-to-end before the gate is judged.
• Entitlements must survive reinstall and restore, or the purchase is not real.

Anti-patterns

• do not bolt the purchase moment on after the loop is built
• do not defer analytics or entitlement rails behind content work
• do not ship a slice missing one of the SKU types it claims to support
• do not skip restore/receipt validation in the billing spike
• do not call the slice done on an unreconciled funnel

Handoff and downstream impact

• hand production hardening the lovable slice and the instrumentation contract
• hand the money gate the sandbox purchase proof and the reconciled funnel
• name the loop-back: a failed purchase-intent test returns to the loop design

Completion checklist

• the spec stack exists and the monetization doc is a binding contract
• the slice is shippable fidelity with one of every SKU type
• a sandbox purchase grants an entitlement that survives reinstall/restore
• the funnel reconciles cleanly against pre-committed thresholds

References

• Unit economics model
• Money gate
• Product process
• Product discovery team architecture