# Gearstack

> Gearstack makes two apps. Gearstack Health, available on the App Store with an Apple Watch app, turns health data such as HRV, resting heart rate, sleep and training load into a daily readiness score with plain-language next steps; it includes an AI coach, strength, running and football training in one calendar, and nutrition logging by photo or voice. Gearstack FC is a separate football app with performance tests measured with the smartphone and a player card; it launches on the App Store and Google Play in November 2026 (status October 2026). Both are made by Gearstack Labs in Zagreb, Croatia, and are wellness apps, not medical devices.

The website is available in German (default, at /), English (/en) and Croatian (/hr). The home page introduces the two areas of Gearstack: Health (readiness, training and recovery) and Gearstack FC (the football section with performance tests, a player card and the season). The Health app page is /health (/en/health, /hr/health), the football page is /fc (/en/fc, /hr/fc). Guides use English at the unprefixed path, German under /de/ and Croatian under /hr/.

## Key facts

- Gearstack Health platforms: iPhone with iOS 17 or later; Apple Watch app for watchOS 10 or later.
- App languages: German, English and Croatian.
- Gearstack Health price: free download on the App Store. The subscription costs €5.99 per month (cancellable monthly) or €49.99 per year; subscriptions are managed and cancelled in the App Store.
- Gearstack FC: a separate app for football players on iPhone and Android with 15 performance tests measured with the smartphone (such as 10 m acceleration, jump height from slow-motion video, 5-0-5 agility and the Yo-Yo test), a player card from bronze to gold, duels with friends and a weekly plan around match day; it connects directly to the Polar H10 chest strap and the Polar Loop band. It launches on the App Store and Google Play in November 2026 (status October 2026). The app is free to download; a subscription adds video uploads and health data from a watch or chest strap for €7.99 per month or €59.99 per year (€3.99 or €29.99 for players aged 13 to 17), with the first 7 days free.
- Data sources: the iPhone alone is enough to start (check-ins, training, nutrition, analysis). An Apple Watch adds HRV, resting heart rate, sleep stages and workouts automatically; Fitbit connects through the Fitbit account; other wearables contribute through Apple Health.
- Readiness score: combines sleep, HRV, resting heart rate and the training load of recent days, compares each value with the user’s own normal range of the past weeks and explains the reasons in full sentences.
- AI coach: answers with the user’s own values. Answers come from generative AI, can contain errors and are labelled as AI content in the app. Cloud AI only receives data after explicit consent, which can be withdrawn in the app.
- Privacy: analysis scores are computed on the iPhone; sync between devices is encrypted and processed on EU servers in Frankfurt; health data is not sold.
- Polar devices are open for pre-order for the Black Friday group order: order deadline 2026-10-28, delivery expected mid-November 2026, full refund within 5 working days if the group order does not go ahead. Pre-order prices (25% Croatian VAT included, shipping €4.90): Polar H10 €79.90, Polar Verity Sense €89.90, Polar Loop €128.90, Polar H10 + Loop €204.90, Polar Ignite 3 €199.90, Polar Pacer Pro €209.90, Polar Vantage M3 €299.90, Polar Grit X2 €359.90, Polar Vantage V3 €479.90, Polar Grit X2 Pro €559.90. Polar devices work without Gearstack; the app is optional when buying a device. Device shipping is currently restricted to Croatia.
- Organisations: dashboards for physiotherapy practices, personal trainers, companies and clinics are offered on request. Prices are given in a personal quote and are not published on the website; enquiries go to info@gearstacklabs.com.
- Football clubs: the club dashboard is planned as the S4E research project of Gearstack j.d.o.o.; funding has been applied for, the start is 2027 at the earliest and it is not on sale before 2028.
- Company: Gearstack Labs is a brand of Gearstack, obrt za računalno programiranje i usluge, vl. Kristijan Bezjak, Zagreb, Croatia. Contact: info@gearstacklabs.com, support: support@gearstacklabs.com.

## Main pages

- [Gearstack, German](https://g-stack.app/): home page with the two areas Health and FC ([English](https://g-stack.app/en), [Croatian](https://g-stack.app/hr))
- [Gearstack Health, German](https://g-stack.app/health): app overview, features, prices and FAQ
- [Gearstack Health, English](https://g-stack.app/en/health): the same page in English
- [Gearstack Health, Croatian](https://g-stack.app/hr/health): the same page in Croatian
- [Gearstack FC, English](https://g-stack.app/en/fc): the football section: 15 performance tests measured with the smartphone, a player card from bronze to gold, progress, duels with friends and the week around match day; the app launches on the App Store and Google Play in November 2026 ([German](https://g-stack.app/fc), [Croatian](https://g-stack.app/hr/fc))
- [Shop](https://g-stack.app/en/shop): app subscription, chest strap and activity band ([German](https://g-stack.app/shop))
- [Support and FAQ](https://g-stack.app/en/support): supported devices, data handling and cancellation ([German](https://g-stack.app/support))
- [Clubs](https://g-stack.app/en/vereine): club dashboard, planned as the S4E research project, start 2027 at the earliest, not on sale before 2028 ([German](https://g-stack.app/vereine))
- [Roadmap](https://g-stack.app/en/roadmap): what is live and what comes next ([German](https://g-stack.app/roadmap), [Croatian](https://g-stack.app/hr/roadmap))
- [Journal](https://g-stack.app/blog): articles on HRV, sleep, recovery, training and football ([German](https://g-stack.app/de/blog), [Croatian](https://g-stack.app/hr/blog))
- [App Store](https://apps.apple.com/app/gearstack-health/id6760966000): download Gearstack Health for iPhone and Apple Watch

## Guides

### HRV

- [The watch shows poor recovery, you feel great: whom to believe?](https://g-stack.app/blog/uhr-zeigt-schlechte-erholung): Why sports watch and body feeling diverge on recovery, which measurement errors may be behind it and the simple rule for combining both signals. ([German](https://g-stack.app/de/blog/uhr-zeigt-schlechte-erholung), [Croatian](https://g-stack.app/hr/blog/uhr-zeigt-schlechte-erholung))
- [Resting heart rate: what is normal and what it reveals](https://g-stack.app/blog/ruhepuls-normalwerte-alter): Which resting heart rate counts as normal in adults, why a low value is not automatically good, and when a rise actually means something. ([German](https://g-stack.app/de/blog/ruhepuls-normalwerte-alter), [Croatian](https://g-stack.app/hr/blog/ruhepuls-normalwerte-alter))
- [HRV by age: what your number actually tells you](https://g-stack.app/blog/hrv-normalwerte-alter): The HRV ranges that show up in studies of healthy adults, how strongly age shifts them, and why your own baseline beats any chart. ([German](https://g-stack.app/de/blog/hrv-normalwerte-alter), [Croatian](https://g-stack.app/hr/blog/hrv-normalwerte-alter))
- [Alcohol and HRV: what an evening drink does to your night](https://g-stack.app/blog/alkohol-hrv-nacht): Why HRV drops and heart rate rises after alcohol, how strongly dose matters, and how to observe your own response cleanly. ([German](https://g-stack.app/de/blog/alkohol-hrv-nacht), [Croatian](https://g-stack.app/hr/blog/alkohol-hrv-nacht))
- [Caffeine and HRV: does coffee distort your morning reading?](https://g-stack.app/blog/koffein-hrv-morgenwert): When coffee can influence an HRV reading, why the direction is not predictable, and how to keep measurements comparable. ([German](https://g-stack.app/de/blog/koffein-hrv-morgenwert), [Croatian](https://g-stack.app/hr/blog/koffein-hrv-morgenwert))
- [Low HRV, but you feel good: which signal should you follow?](https://g-stack.app/blog/hrv-vs-koerpergefuehl): What to do when HRV and how you feel do not match, and how a calm warm-up helps you decide. ([German](https://g-stack.app/de/blog/hrv-vs-koerpergefuehl), [Croatian](https://g-stack.app/hr/blog/hrv-vs-koerpergefuehl))
- [Why HRV changes from night to night, and when that matters](https://g-stack.app/blog/hrv-nachts-schwankungen): How much your nightly HRV is expected to move, what drives the swings, and the point where a deviation actually means something. ([German](https://g-stack.app/de/blog/hrv-nachts-schwankungen), [Croatian](https://g-stack.app/hr/blog/hrv-nachts-schwankungen))
- [Understanding HRV: what heart rate variability says about recovery](https://g-stack.app/blog/hrv-verstehen): What heart rate variability actually measures, why there is no normal value, and how to read your own trend with a seven-day average. ([German](https://g-stack.app/de/blog/hrv-verstehen), [Croatian](https://g-stack.app/hr/blog/hrv-verstehen))
- [Resting heart rate, HRV and sleep: what actually connects](https://g-stack.app/blog/ruhepuls-hrv-schlaf): Why resting heart rate and HRV do not measure the same thing, what it means when they diverge, and which combinations are worth acting on. ([German](https://g-stack.app/de/blog/ruhepuls-hrv-schlaf), [Croatian](https://g-stack.app/hr/blog/ruhepuls-hrv-schlaf))

### Sleep

- [How much sleep do I actually need?](https://g-stack.app/blog/schlafbedarf-nach-alter): What sleep duration is recommended for adults, why your own need may legitimately differ, and how to find it yourself over two weeks. ([German](https://g-stack.app/de/blog/schlafbedarf-nach-alter), [Croatian](https://g-stack.app/hr/blog/schlafbedarf-nach-alter))
- [Not enough REM sleep: when the number is a problem](https://g-stack.app/blog/rem-schlaf-zu-wenig): How much REM sleep is typical in adults, why a low reading is usually harmless, and the four things that reliably cut it short. ([German](https://g-stack.app/de/blog/rem-schlaf-zu-wenig), [Croatian](https://g-stack.app/hr/blog/rem-schlaf-zu-wenig))
- [Power naps: the ideal length and timing for a short nap](https://g-stack.app/blog/powernap-timing-dauer): What research says about ideal nap length, why 30 minutes often backfires, and when napping starts to threaten your night sleep. ([German](https://g-stack.app/de/blog/powernap-timing-dauer), [Croatian](https://g-stack.app/hr/blog/powernap-timing-dauer))
- [Catching up on sleep at the weekend: what it can restore](https://g-stack.app/blog/wochenende-schlaf-nachholen): What longer weekend sleep can restore, what may remain, and how to recover while keeping your schedule steady. ([German](https://g-stack.app/de/blog/wochenende-schlaf-nachholen), [Croatian](https://g-stack.app/hr/blog/wochenende-schlaf-nachholen))
- [Seven nights, one rhythm: an experiment in sleep consistency](https://g-stack.app/blog/sieben-naechte-schlafkonstanz): A practical seven-night experiment for observing your sleep rhythm, with a fixed wake-up time as the anchor. ([German](https://g-stack.app/de/blog/sieben-naechte-schlafkonstanz), [Croatian](https://g-stack.app/hr/blog/sieben-naechte-schlafkonstanz))
- [Sleep quality beats sleep duration](https://g-stack.app/blog/schlafqualitaet-vs-dauer): Why eight hours is not a target, what sleep quality actually means, and which lever gives you the most in daily life. ([German](https://g-stack.app/de/blog/schlafqualitaet-vs-dauer), [Croatian](https://g-stack.app/hr/blog/schlafqualitaet-vs-dauer))
- [How much deep sleep is normal? Typical shares by age](https://g-stack.app/blog/tiefschlaf-normalwerte): What share of deep sleep is typical, why wearables can only estimate it, and what reliably reduces it. ([German](https://g-stack.app/de/blog/tiefschlaf-normalwerte), [Croatian](https://g-stack.app/hr/blog/tiefschlaf-normalwerte))

### Training

- [10 m sprint in football: what is a good time?](https://g-stack.app/blog/10-meter-sprint-gute-zeit): What is a good 10 m time? German FA benchmarks from U11 to U15 for boys and girls, academy values and why the timing method shifts results by tenths. ([German](https://g-stack.app/de/blog/10-meter-sprint-gute-zeit), [Croatian](https://g-stack.app/hr/blog/10-meter-sprint-gute-zeit))
- [Winter fitness testing: how football clubs measure progress over weeks](https://g-stack.app/blog/athletiktest-winter-fussball): Which fitness tests actually carry meaning in winter preparation, how resting heart rate, HRV and running efficiency show progress over weeks and how a club turns them into one athletic score. ([German](https://g-stack.app/de/blog/athletiktest-winter-fussball), [Croatian](https://g-stack.app/hr/blog/athletiktest-winter-fussball))
- [HRV in football training: what heart rate variability really tells the coach](https://g-stack.app/blog/hrv-fussball-training): How heart rate variability is used in football, why the trend against the personal baseline is what counts, which measurement mistakes happen and how a team uses the values in practice. ([German](https://g-stack.app/de/blog/hrv-fussball-training), [Croatian](https://g-stack.app/hr/blog/hrv-fussball-training))
- [Documenting player development: what clubs should record and what they can skip](https://g-stack.app/blog/spielerentwicklung-dokumentieren): Which data actually proves a football player’s development, how much documentation is realistic in club life and how notes become a development story per player. ([German](https://g-stack.app/de/blog/spielerentwicklung-dokumentieren), [Croatian](https://g-stack.app/hr/blog/spielerentwicklung-dokumentieren))
- [Day-to-day readiness in football: how coaches judge it before writing the line-up](https://g-stack.app/blog/tagesform-aufstellung-fussball): Why the warm-up impression comes too late, which morning values reveal a player’s readiness and how a squad overview supports the line-up on matchday. ([German](https://g-stack.app/de/blog/tagesform-aufstellung-fussball), [Croatian](https://g-stack.app/hr/blog/tagesform-aufstellung-fussball))
- [A team dashboard for football clubs: what it must show so coaches actually use it](https://g-stack.app/blog/team-dashboard-fussballverein): Professional clubs have long managed training through data. What a team dashboard needs to show for amateur and youth clubs, why three inputs are enough and where these systems fail in daily use. ([German](https://g-stack.app/de/blog/team-dashboard-fussballverein), [Croatian](https://g-stack.app/hr/blog/team-dashboard-fussballverein))
- [Recording training load: how far the spreadsheet carries and where the dashboard begins](https://g-stack.app/blog/trainingsbelastung-excel-tabelle): Load management with Excel: what a good spreadsheet needs, the three places where it tears in club life and when switching to a team dashboard pays off. ([German](https://g-stack.app/de/blog/trainingsbelastung-excel-tabelle), [Croatian](https://g-stack.app/hr/blog/trainingsbelastung-excel-tabelle))
- [Managing training load in youth football: one simple number per session](https://g-stack.app/blog/trainingsbelastung-jugendfussball): How youth coaches measure training load with one number per session, why rapid load spikes are the real risk and what a weekly overview looks like in a team dashboard. ([German](https://g-stack.app/de/blog/trainingsbelastung-jugendfussball), [Croatian](https://g-stack.app/hr/blog/trainingsbelastung-jugendfussball))
- [Training management in a football club: methods for amateur coaching staff](https://g-stack.app/blog/trainingssteuerung-fussballverein): What training management means, which methods have proven themselves in amateur football (session RPE, weekly load, ACWR, readiness) and how a club gets started with simple tools. ([German](https://g-stack.app/de/blog/trainingssteuerung-fussballverein), [Croatian](https://g-stack.app/hr/blog/trainingssteuerung-fussballverein))
- [Youth football injuries are rising: the reasons, and what actually protects players](https://g-stack.app/blog/sportverletzungen-jugendliche-fussball): Why sports injuries in children and adolescents have been increasing for years, the role of growth, early specialisation, load spikes and sleep, and what clubs and parents can do about it. ([German](https://g-stack.app/de/blog/sportverletzungen-jugendliche-fussball), [Croatian](https://g-stack.app/hr/blog/sportverletzungen-jugendliche-fussball))
- [Calculating maximum heart rate: why 220 minus age misses](https://g-stack.app/blog/maximalpuls-berechnen): Where the 220 minus age rule came from, how far it deviates, which alternative is more accurate, and how to find your real value. ([German](https://g-stack.app/de/blog/maximalpuls-berechnen), [Croatian](https://g-stack.app/hr/blog/maximalpuls-berechnen))
- [How long does recovery after strength training take?](https://g-stack.app/blog/regeneration-nach-krafttraining): Why the same muscle group needs anywhere from one to four days, what soreness really tells you, and how to recognise that recovery is done. ([German](https://g-stack.app/de/blog/regeneration-nach-krafttraining), [Croatian](https://g-stack.app/hr/blog/regeneration-nach-krafttraining))
- [The deload week: training less on purpose to keep progressing](https://g-stack.app/blog/deload-woche-erholung): Why a reduced training week is not a lost week, what studies say about losing muscle and strength, and how to structure a deload in practice. ([German](https://g-stack.app/de/blog/deload-woche-erholung), [Croatian](https://g-stack.app/hr/blog/deload-woche-erholung))
- [Zone 2 without a lab test: finding a useful working range](https://g-stack.app/blog/zone-2-ohne-labortest): Why Zone 2 is not one universal heart-rate number, and how the talk test, perceived effort and repeatable sessions can define a useful field range. ([German](https://g-stack.app/de/blog/zone-2-ohne-labortest), [Croatian](https://g-stack.app/hr/blog/zone-2-ohne-labortest))
- [Push, Balance or Easy: three levels for your training decision](https://g-stack.app/blog/push-balance-easy): Combine readiness, how you feel and the goal of a session into one graduated choice for today’s training. ([German](https://g-stack.app/de/blog/push-balance-easy), [Croatian](https://g-stack.app/hr/blog/push-balance-easy))
- [Readiness score explained: how your daily number is built](https://g-stack.app/blog/readiness-score-erklaert): What goes into a daily readiness value, why the weighting is harder than it looks, and the situations where the score gets it wrong. ([German](https://g-stack.app/de/blog/readiness-score-erklaert), [Croatian](https://g-stack.app/hr/blog/readiness-score-erklaert))
- [Training by readiness: when load actually makes sense](https://g-stack.app/blog/training-nach-tagesform): How to adapt a training plan to your recovery values by adjusting intensity, and when to ignore the number entirely. ([German](https://g-stack.app/de/blog/training-nach-tagesform), [Croatian](https://g-stack.app/hr/blog/training-nach-tagesform))

### Everyday

- [How accurate is your sports watch’s calorie burn? Honest answer: surprisingly inaccurate](https://g-stack.app/blog/kalorienverbrauch-sportuhr): Studies show errors of 30 percent and more in sports watch energy expenditure while heart rate measurement performs well. What the calorie number is still good for: comparing your own similar sessions. ([German](https://g-stack.app/de/blog/kalorienverbrauch-sportuhr), [Croatian](https://g-stack.app/hr/blog/kalorienverbrauch-sportuhr))
- [Understanding sports watch values: the five numbers that count, and the ones you can ignore](https://g-stack.app/blog/sportuhr-werte-verstehen): Resting heart rate, sleep, HRV, load: which sports watch values actually say something, which are mostly show, and why the first two weeks are only for wearing. ([German](https://g-stack.app/de/blog/sportuhr-werte-verstehen), [Croatian](https://g-stack.app/hr/blog/sportuhr-werte-verstehen))
- [How much water a day? What the two litres really mean](https://g-stack.app/blog/wie-viel-wasser-am-tag): Where the common guideline figures come from, why food counts, and the more reliable sign that you had enough. ([German](https://g-stack.app/de/blog/wie-viel-wasser-am-tag), [Croatian](https://g-stack.app/hr/blog/wie-viel-wasser-am-tag))
- [Waking at three in the morning: why it is normal](https://g-stack.app/blog/nachts-um-drei-aufwachen): Why brief waking between sleep cycles is ordinary physiology, when it tips into a disorder, and what actually helps in the moment. ([German](https://g-stack.app/de/blog/nachts-um-drei-aufwachen), [Croatian](https://g-stack.app/hr/blog/nachts-um-drei-aufwachen))
- [Sleeping through heat: what warm nights do to your recovery](https://g-stack.app/blog/schlafen-bei-hitze): Why sleep suffers at high temperatures, what sensor and wearable studies show, and which ways of cooling down actually help. ([German](https://g-stack.app/de/blog/schlafen-bei-hitze), [Croatian](https://g-stack.app/hr/blog/schlafen-bei-hitze))
- [Understanding smartwatch stress data: what the signal shows](https://g-stack.app/blog/stressdaten-smartwatch-einordnen): What a stress score built from heart rate and HRV can show, what it misses, and how to check your personal pattern across several days. ([German](https://g-stack.app/de/blog/stressdaten-smartwatch-einordnen), [Croatian](https://g-stack.app/hr/blog/stressdaten-smartwatch-einordnen))
- [Exercise snacks: how short movement sessions fit real life](https://g-stack.app/blog/exercise-snacks-alltag): Short movement sessions can lower the barrier to starting. What exercise-snack research shows, where its limits sit, and how to plan them sensibly. ([German](https://g-stack.app/de/blog/exercise-snacks-alltag), [Croatian](https://g-stack.app/hr/blog/exercise-snacks-alltag))
- [What an AI health coach can do, and where it stops](https://g-stack.app/blog/ki-gesundheitscoach-grenzen): Where an AI coach with access to your data genuinely helps, what it necessarily fails at, and how to get useful answers out of it. ([German](https://g-stack.app/de/blog/ki-gesundheitscoach-grenzen), [Croatian](https://g-stack.app/hr/blog/ki-gesundheitscoach-grenzen))
- [Night shifts: what recovery data says about your rhythm](https://g-stack.app/blog/nachtschicht-erholungsdaten): Why HRV and resting heart rate look different on rotating shifts, where the measurement hits its limits, and how to read your trend anyway. ([German](https://g-stack.app/de/blog/nachtschicht-erholungsdaten), [Croatian](https://g-stack.app/hr/blog/nachtschicht-erholungsdaten))
- [Shift work and sleep: routines that survive a rotating schedule](https://g-stack.app/blog/schichtarbeit-schlaf-routinen): Why shift work breaks the rhythm, which lever actually works, and which routines hold up when the roster keeps changing. ([German](https://g-stack.app/de/blog/schichtarbeit-schlaf-routinen), [Croatian](https://g-stack.app/hr/blog/schichtarbeit-schlaf-routinen))

### Community

- [Parent meetings in youth football: talking calmly about playing time with data](https://g-stack.app/blog/elterngespraech-jugendfussball): How youth coaches prepare parent meetings, why documented development defuses the argument about playing time and which data belongs in the conversation. ([German](https://g-stack.app/de/blog/elterngespraech-jugendfussball), [Croatian](https://g-stack.app/hr/blog/elterngespraech-jugendfussball))
- [Exercise after a cold: when you can start again](https://g-stack.app/blog/sport-nach-erkaeltung): The neck check as a simple decision aid, why fever is a hard line, and what a sensible return after an infection looks like. ([German](https://g-stack.app/de/blog/sport-nach-erkaeltung), [Croatian](https://g-stack.app/hr/blog/sport-nach-erkaeltung))
- [How many steps a day actually make sense?](https://g-stack.app/blog/schritte-pro-tag-sinnvoll): Where the 10,000 really came from, what large analyses show as the useful range, and why the number adds up more easily in company. ([German](https://g-stack.app/de/blog/schritte-pro-tag-sinnvoll), [Croatian](https://g-stack.app/hr/blog/schritte-pro-tag-sinnvoll))
- [Training partners: why you last longer in a team than alone](https://g-stack.app/blog/trainingspartner-koehler-effekt): The Köhler effect explains why people train markedly longer with a partner, which conditions it needs, and how to put it to work for you. ([German](https://g-stack.app/de/blog/trainingspartner-koehler-effekt), [Croatian](https://g-stack.app/hr/blog/trainingspartner-koehler-effekt))
- [Streaks and rest days: making recovery part of your run](https://g-stack.app/blog/streaks-ruhetage-motivation): A useful fitness streak rewards meaningful consistency across the whole week. Here is how rest, motivation, and personal goals can belong to one routine. ([German](https://g-stack.app/de/blog/streaks-ruhetage-motivation), [Croatian](https://g-stack.app/hr/blog/streaks-ruhetage-motivation))
- [Fair fitness challenges: rewarding personal progress](https://g-stack.app/blog/faire-fitness-challenges): Why one shared step target is rarely fair, and how personal baselines, recovery, and social rules can turn a challenge into useful motivation. ([German](https://g-stack.app/de/blog/faire-fitness-challenges), [Croatian](https://g-stack.app/hr/blog/faire-fitness-challenges))

## Company

- [Legal notice](https://g-stack.app/imprint): Gearstack Labs, Zagreb, Croatia
- [Privacy policy](https://g-stack.app/privacy): data handling in the app and on the website
- [Terms](https://g-stack.app/terms): subscriptions and digital services
- [Delete account](https://g-stack.app/en/delete-account): how to delete a Gearstack Health account and which data is deleted ([German](https://g-stack.app/konto-loeschen), [Croatian](https://g-stack.app/hr/brisanje-racuna))

## Optional

- [Full reference](https://g-stack.app/llms-full.txt): key facts, all questions and answers and guide summaries in one file