Pay-per-use sounds simple: count bytes, charge, pay the creator 70 %. Building it honestly meant finding where it broke. Four places.
1. The heavy viewer pays 3.5× a subscription
Occasional viewers win big under pay-per-use ($1.19 for four 720p films). A viewer watching three hours a day at 4K pays about $77.68 a month. Without protection, the most engaged users leave. Fix: a monthly spending cap chosen by the viewer, with three behaviours at the limit — stop, continue with ads (default), or drop to the cheapest quality. The promise becomes never more expensive than a subscription.
2. Billing the ceiling, not the bytes
Each quality rung had a nominal bitrate — the encoder's -maxrate. Billing used it. With constant-quality encoding, real output sits 2.7–3.2× below the ceiling. Viewers were charged 1.8× too much on average. Fix: bill sizeBytes / duration of the actual rendition (billingBasis: measured); fall back to nominal only for untranscoded titles, and mark those estimated.
3. Downloads were free
The download path recorded bytes and left billedUsd: 0. The whole catalogue could be downloaded in 4K for nothing, and the creator's 70 % was never paid. Fix: bill the increment against what was already billed, with an idempotency key that carries the running total, so a resumed download cannot be double-charged or skipped.
4. The counter charged itself
Playback progress is saved every 10 seconds. Each save was metered as an API write at $0.0002. A two-hour film accumulated $0.14 in bookkeeping alone — more than watching it at 480p. A download's progress report was billed twice for the same act. Fix: the metering middleware exempts /playback/progress, /downloads/:id/progress, /usage/events and /qoe.
The rule that came out
In pay-per-use, everything the app is obliged to send for the product to work is exempt. Only what the user asks for is billed. Applicable to every pay-per-use product in the ecosystem.
A fifth non-finding
PhoonoS discovered its assumed serving cost of $0.09/GB was really $0.12. The temptation was to update EidoOS too. Wrong: EidoOS's price is derived from its cost constant (PRICE = COST × 1.5), so raising the constant raises every viewer's bill by 33 % — and the two products sit at opposite ends of the provider's marginal tiers. Verified and left alone on 2 September 2026.
Why publish the holes
Because a pay-per-use platform that claims fairness should show its arithmetic. These four were found by testing live, not by review; the app is in internal testing and has not yet charged a real viewer. The page this replaces listed games at a gaming festival on another chain.
Based on the EidoOS pay-per-use economics (2026-08-21 to 09-02).