A focused Android reader for senior product managers who need to make build / buy / skip calls on AI features — and back the call up with calibrated reasoning. Fifteen units, in order, each one a single trade-off. No streaks. No badges. No daily nudge.
Most AI-fluency content treats PMs like coding-bootcamp students. Perpenda treats you like the decision-maker you are. Every unit teaches one concept through the same three-question scaffold — because that's how product decisions actually get made.
Each unit names the concrete decisions the concept changes — cost forecasts, latency budgets, vendor comparisons, scoping calls. Not "important to know," but "load-bearing for these decisions."
Failure modes, named. Estimating cost in words instead of tokens. Treating latency as one number. Shipping streaming UX where output is consumed atomically. The mistakes you can recognize after, but ought to recognize before.
The discipline the right call demands — naming three latency metrics instead of one, asking eng for benchmarks on your prompt shape, measuring before promising. Cheaper than the failure mode it prevents.
Real terms, straight from the units — each one attached to a decision you actually have to make. Fluency you can use on Monday, not trivia.
One path, in v1. LLM Systems for PMs. Fifteen units are published; more are shaped by the closed beta, rather than planned from the armchair.
The whole loop, screen by screen — find your next unit, read the bite, decide, get per-criterion grading, see the sources, and return for spaced review. Editorial typography, hairline rules, no decorative imagery — the restraint makes the writing earn its space.
Each unit's claims carry a tier: settled, contested, or unsettled. Sources sit after the decision prompt — never before — so the consensus doesn't prime your answer. The grader will tell you when it doesn't have enough signal to grade fairly.
Perpenda is a focused Android reader that teaches LLM systems to senior product managers — one trade-off at a time. It works through a curated path of single-trade-off units, in a fixed order, with calibrated grading against rubric criteria. No streaks, no badges, no daily nudge.
Product professionals with stakes in AI-shaping decisions — product managers first, but also product marketers, founders, design leads, and product-adjacent execs, plus career-switchers moving into the field. Anyone who makes build / buy / skip calls on AI features and needs to back them with calibrated reasoning — people who'd rather decide right than read fast.
Perpenda teaches decisions before mechanism. Every unit is a single trade-off — when it matters, when it breaks, what it costs to get right — and every claim is sourced and tagged by confidence (settled, contested, unsettled). The aim is judgment you can act on, not theory you can recite.
Perpenda is an open-source Android app, released under the GPL-3.0 license, with no ads and no behavioural tracking. All you need to run it is a modern Android phone and an account.
Fifteen units are published today, each a single decision trade-off. The final units are deliberately left open — they're shaped during the closed beta rather than planned in advance.
Each unit's claims carry a calibration tier — settled, contested, or unsettled — and sources sit after the decision prompt, never before, so the consensus doesn't prime your answer. The grader will tell you when it doesn't have enough signal to grade fairly.
Fifteen units, calibrated grading, the full loop. More units are shaped by real use, not the armchair.