§27's purpose is one sentence — show the user what the app has learned — which
means the screen has to be honest about how little that sometimes is. Every
figure is absent rather than approximated below the history that supports it,
because the easiest way to overstate accuracy is to average two numbers and
print a decimal place.
- one interval is an anecdote, not an average: no "average cycle" until two
- accuracy figures wait for three scored forecasts, and say why they are
waiting rather than showing a mean of one
- §27's learning copy is chosen by what the data supports, never by mood.
"Personalized to your cycle" is a claim, and it appears only when there are
enough confirmed cycles for the forecast to genuinely be hers
A BUG THE OUTLIER TEST CAUGHT
The typical-range quartiles were indexed off `size` instead of `size - 1`, which
on an even-length list puts the upper index on the largest value. A history of
29, 28, 30, 29, 61, 29 reported a "typical range" of 29–61 — describing a
regular cycle as wildly erratic, on the one screen whose whole job is to say
what has been learned about her. Now 29–30.
Nothing on this screen leaves the device. §46 names prediction_error= among the
values that must never become an analytics event, and this is exactly the screen
that would tempt somebody to send one. There is no network call in these files
and there must never be.
153 tests, all passing. ./gradlew check green.
closes#20
Period was a bare directory holding one 2,527-line specification, with no git
repository, no tracker and no documentation convention. This is the adoption
from Projects/Template/START-HERE-New-Project.md, plus a project that compiles
so the hooks and future guards have something real to run against.
Documents. scaffold.sh created 19 paths, 0 skipped. The specification moved to
docs/planning/PRODUCT_PLAN.md unchanged in substance, with a status header; the
capitalised Docs/ is gone. Every scaffolded document was filled in for Period.
docs/OPERATIONS.md deleted — an offline app is not a deployed service.
DOC_TRUST_MAP.md written last, describing what is actually here, including what
this project deliberately does not have.
Code. Four Gradle modules. domain/cycle and domain/prediction are kotlin("jvm")
and cannot see the Android SDK, so the engine is testable without an emulator —
17 tests pass, 12 of them the acceptance cases from PRODUCT_PLAN.md §51.
BaselinePredictionEngine is a robust-median prototype and explicitly not the
product; it exists so Batch 02's replacement can be shown to be better rather
than merely different.
Versions verified against their official sources today rather than inherited
from the specification's own numbers, which that document asks for: Kotlin
2.4.10, AGP 9.3.1, Gradle 9.7.0, Compose BOM 2026.08.00, Room 2.8.4, Hilt
2.60.1. AGP 9 ships Kotlin built in, so org.jetbrains.kotlin.android is no
longer applied. compileSdk is 37 because current AndroidX requires it; targetSdk
stays 36, Play's floor from 2026-08-31, and the difference is deliberate.
Six scripts taken into scripts/; the rest declined and named in docs/TOOLS.md.
Three hooks in .githooks/, with pre-commit adapted to Gradle.
closes#1closes#2
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