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Diamond Coach Pro+ app icon

Diamond Coach Pro+

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Plan a 90-minute youth baseball or softball practice in under two minutes, then run game day from the same app.

MobileAIiOS
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Diamond Coach Pro+ home screen greeting Coach Griffin, showing the next practice, Hitting & Fielding, with quick actions for a new practice, drills, games, and lineups.

Problem

Volunteer coaches were burning hours assembling practices from PDFs and YouTube and still showing up on Tuesday without a real plan.

Solution

Generates a balanced, age-appropriate practice plan in seconds from a 237-drill video library, then carries the coach through game day with a live lineup board, pitch-count enforcement, and one-tap stat tracking.

Plan practice form with age group chips from 7U to 12U, a total-time slider set to 50 minutes, a start time, and focus areas Hitting and Fielding selected.
A generated 50-minute practice plan listing timed drills such as Hips Fire First Tee Drill, Short Hops, and Wiffle Ball Circle.
Drill library of 237 drills with search, sport and skill filters, and video drill cards recommended for 8U.
Player growth card for a catcher showing eight skill ratings with trend sparklines and coach notes.
Live game stat logging screen with the batting order, per-player averages, and tap counters for hits, walks, and outs.
Lineup builder for a game with twelve batters, an auto-generate-from-stats button, and drag handles to assign positions.
Import stats screen for pulling GameChanger season CSV or single-game PDF box scores into the roster.

Key features

  • 237 video drills with coaching points and equipment requirements, filterable by age and focus
  • Practice planner: enter age, focus, and duration, get a timed agenda that auto-saves
  • Live in-game board: field diagram with position chips, batter carousel, pitch counter, per-inning snapshots
  • Pitch-count tracker with Little League, USSSA, and Cal Ripken rest-day rules that blocks ineligible pitchers
  • Roster with 8-skill ratings and trend sparklines
  • Lineup builder with batting order, defensive positions, 9- and 10-player layouts
  • GameChanger import: season CSV and single-game PDF box scores parsed by an LLM with a staged review step
  • Attendance tracking, PDF practice plans and player season reports, bulk export
  • Tryout pools, candidates, and evaluations
  • Push reminders, bookmarks, paywall, account deletion

Engineering highlights

The parts that separate a product from a template.

League-specific pitch-rules engine

Little League, USSSA, and Cal Ripken pitch-count and rest-day rules encoded once and enforced live, so an ineligible pitcher can't be put on the mound.

LLM document ingestion

A PDF box score becomes structured stats, matched to the roster, with a staged review step before anything is saved.

Live game state machine

Game state is persisted per half-inning, so a dropped connection or a closed app never loses the scorebook.

Client-side PDF reports

HTML-to-PDF practice plans and player season reports, generated on the phone, single or in bulk.

Apple-compliant account deletion

An edge function removes the account and its data end to end, meeting App Store guideline 5.1.1.

Tech stack

Mobile

Expo SDK 55React Native 0.83React 19TypeScriptBunExpo Router (typed routes)TanStack QueryUnistylesexpo-notificationsexpo-print

Backend

SupabaseEdge FunctionsLLM API (server-side)

Infrastructure

EAS Build

Services

RevenueCat

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