Evidence Engine v1
Data that defends the learning claim
Every mission emits structured events — not open chat logs. Devices store offline-first; the MentorStar API ingests to Postgres, rolls up sessions, and can draft pilot narratives with Gemini.
Mastery
≥80%
Post-test + stable in-game flags
Retention
≥70%
Day-30 micro-checks
Transfer
≥60%
Real-world application
Event taxonomy
session_start / session_end / safe_exit
Session health & honorable exits
mission_start / mission_complete
Exposure and completion
attempt_submitted
Accuracy, response time, item id
hint_requested / hint_shown
Scaffold dependence L1–L3
mastery_state_changed
In-game mastery ladder
transfer_prompt_shown / transfer_verified
Home application signal
Proof Card (parents)
Derived narrative: what improved, what's next, and a home transfer suggestion — trust-first, never a grade report.
Pipeline
App SessionEngine → EvidenceEvent → local store → POST /v1/events → Postgres
→ session_facts rollups → pilot export / admin dashboard → optional Gemini narrative