IntervalAnalysis turns confirmed starts into weighted intervals and decides what
looks questionable — relative to this user's own history, never to a constant.
That distinction is the whole point. A global "over 40 days is suspicious" rule
gets exactly one group wrong, and it is the group whose cycles are already
unusual: the person this product exists for, and the one most tired of apps
assuming she is average. 45 days is unremarkable at a usual of 43 and worth
questioning at a usual of 29. Both are tests.
Two flags, because they earn different responses. A gap near a whole multiple of
the usual is a probable missed entry and produces §14's question. A gap merely
far from usual is down-weighted and left alone — asking would be the
over-questioning §25 warns against, and §51's 45-against-29 outlier is exactly
that case.
Nothing is ever dropped. §12 step 2: unusual data is marked for review or given
less influence, never silently deleted. A questionable interval keeps a quarter
of its recency weight, and a test asserts it is still present and still counts.
Recency decay is here too, ready for the centre in #10: newest cycle weight 1.0,
each older one 0.85 of the last.
12 new tests. The §51 acceptance cases still pass unchanged.
closes#13
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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