Training Days

A phone-first training app: pick a session, hit start, work the checklist. Thirty-nine plans across free weights, elastic bands, bodyweight, climbing-gym days, soccer, golf, knee rehab, standing-only travel sessions, band work for walks and bus stops, and warm-ups, with a session clock, superset grouping, a rest timer, an interval timer, and form cues on every exercise.

Everything is stored in localStorage. No account, no database, no server calls. A backup in Settings exports it to one JSON file and merges it back in on any device.

Plans

Category	Plans	Length
Free Weights	Push Day, Pull Day, Legs & Core, Dumbbell Express	40-75 min
Elastic Bands (bands + a door)	Upper Body, Legs & Glutes, Full-Body Express, Shoulder & Elbow Prehab	15-60 min
Bodyweight (floor + one chair)	Push & Core, Pull & Posterior, Legs, Express Circuit	25-55 min
Climbing Gym (wall, hangboard, weights)	Hangboard & Limit Boulders, Power Endurance 4x4s, Repeaters & Volume, Technique & Movement	60-120 min
Soccer	Injury Prevention, Strength & Power, Speed & Agility, Ball Skills & Touch, Match Day Warm-Up	20-65 min
Golf	First Tee Warm-Up, Range Warm-Up, Strength & Power, Clubhead Speed, Mobility & Back Care	8-55 min
Knee Care	Phase 1: Calm & Activate, Phase 2: Build Strength, Phase 3: Load & Return, Knee Prep Before Sport	8-45 min
Standing Only (nothing, one square metre)	Gate Area Reset, Long-Haul Recovery, Standing Climber Prehab	8-20 min
On the Move (one band, no anchor)	Band Walk, Bus Stop Band	6-25 min
Warm-Up & Recovery	Express Warm-Up, Full Warm-Up, Pre-Gym Activation, Post-Session Recovery	10-30 min

Elastic Bands exists because bands load the opposite way to free weights — hardest at the end of the range, easiest at the start — which makes them better than dumbbells for shoulder, rotator cuff and glute-medius work and worse for anything you want heavy. Rep ranges run higher to match.

Soccer leads with injury prevention because it is the only part of this app with a serious evidence base: meta-analyses of the Nordic hamstring exercise in football squads report roughly a halving of hamstring injury rates, trials of Copenhagen adduction report a large reduction in groin problems, and FIFA 11+ style warm-ups report around a third fewer injuries overall. Figures vary by study and by adherence, so the plan notes give them as orders of magnitude rather than precise numbers. Everything else in the category — speed, power, touch — is ordinary programming.

Golf splits into two warm-ups and three training sessions. The warm-ups contain no static stretching: in a trial of young competitive golfers, holding stretches before swinging reduced clubhead speed, distance and quality of contact, so the holds live in the mobility session instead. The training sessions put rotational and lower-body power first, because those track clubhead speed more closely than arm strength, and finish on the lead elbow and the low back, the two places amateur golfers most often get sore.

Knee Care is phased rehab rather than a menu: calm an irritable knee with isometrics and activation, build quad and hip strength (combined hip and knee work has the strongest evidence for kneecap pain), then load it heavy and slow and add landing before returning to sport. Every phase names the numbers that unlock the next one. Progress is paced by symptoms, not the calendar, using the pain-monitoring model physiotherapists use for tendon and kneecap pain: up to 3/10 during the work is acceptable if it has settled by the next morning. The morning check-in on the Knee filter records two 0-10 readings and turns them into a call: step back if either is over 3, hold if morning pain rose by 2 or more since the last check-in, progress after three clean check-ins in a row. The rule is a pure function with its own tests. None of this is a diagnosis, and every phase plan says when to see a clinician instead.

Standing Only has a hard constraint: nothing touches the floor, no chair, no kneeling, and it fits in about one square metre. Built for a gate area or a hotel corridor. A wall is used only for balance and every exercise that mentions one works without it.

On the Move is band work with no door: everything is self-anchored, held in the hands or stood on. The walk session is hand-held only, so you never stop walking; the bus-stop session is written in priority order in self-contained blocks, because the bus decides when it ends. A test keeps anchored movements out of the category and stood-on movements out of the walk.

Loads are left to the athlete. Plans prescribe reps, rest and intent only.

Features

• Works offline and installs to the home screen. A service worker precaches the shell and every exercise image, so the app runs with no signal — the normal condition in a basement gym.

• Session clock with pause/resume, persisted across reloads and browser restarts.

• Checklist per exercise per round. Multi-round single-exercise blocks (max hangs, limit boulder attempts) collapse into numbered set buttons.

• Superset and circuit grouping, marked with a badge and a colored rail so paired work is obvious at a glance.

• Exercise overlay with a large illustration, form cues and step-by-step instructions. Opens from a session, the library, or a plan you have not started yet, and never reflows the page behind it.

• Back button works. Every view and every overlay is a history entry, so the Android back gesture walks back through the app instead of leaving it. Views are URLs, so a session survives a reload and a plan can be linked to directly.

• Rest timer in a fixed bottom bar, with the current block's prescribed rest preselected. Audio countdown on the last three seconds.

• Interval timer for hangboard protocols (7s on / 3s off x 6) and timed circuits (40/20), driven by the block's own spec.

• Per-exercise timers on any prescription that is purely a duration — planks, wall sits, dead hangs, carries. One tap starts it in the bottom bar.

• Session customization: skip a block or change its round count mid-session. Progress recalculates against what you are actually doing.

• Added-weight log on hangboard blocks, off by default and enabled in settings. Prefilled with last session's number, in lb or kg.

• Progression ladders for fifteen movement patterns — push-up, dip, overhead, pull-up, row, squat, hinge, two core ladders, fingers, jumping, adductor, rotation, knee strength and patellar tendon loading. Each rung carries a countable criterion for moving up, and collapsed ladders show a thumbnail strip so you can see the whole progression at a glance. A test rejects any rung whose criterion has no number in it.

• Saved exercises. Star anything from the overlay or the library; the Saved view lists them newest first with per-item removal and a clear-all.

• UI density — compact, normal or comfortable. Row height, card padding, gaps, type size and control size all scale from one set of CSS custom properties on the document root, so a session page runs roughly 1900px tall at compact and 2500px at comfortable.

Stack

Next.js 16 (App Router), React 19, TypeScript, hand-written CSS. No UI framework, no state library, no analytics, three runtime dependencies.

Session state is read through useSyncExternalStore over localStorage, so there is no after-mount hydration flicker. Navigation is a fourth store of the same shape, backed by the History API: lib/navigation.ts owns which view and which overlay are showing, and the URL is the source of truth (?v=week, ?v=preview&p=fw-push, ?...&ex=bench-press). Real Next routes would give back/forward for free, but each route would be another document the service worker has to precache, and the overlay is a layer over a view rather than a view of its own — so one document with explicit history entries handles both uniformly and keeps offline simple. Both timers expand their schedule into wall-clock deadlines and derive the current phase from the clock, which means a backgrounded tab or a locked screen — where browsers throttle timers to roughly once a minute — cannot desynchronize a hangboard set.

Local development

npm install
npm run dev      # http://localhost:3000
npm run build    # production build
npm run check    # typecheck + lint + tests

npm test runs 44 checks with node --test and no test framework. Most guard the data: unresolved exercise keys, duplicate ids, block minutes against the advertised session length, interval specs matching block rounds, image frames present on disk, and week templates never stacking two finger-intensive days. The rest cover duration parsing, the knee check-in rule, session progress counting, Chalk's current-block and next-item logic, the merge rules behind backup import, the pre-paint style script, and the light theme's contrast, read straight from globals.css. Editing lib/plans.ts by hand is the likely way this breaks, and a typo'd exercise key renders nothing at all — which you would discover standing at the hangboard.

Deploying to Vercel

The repo is a stock Next.js app, so Vercel needs no configuration:

1. Import the repository at vercel.com/new.
2. Accept the detected framework preset (Next.js). Build command next build, no env vars.
3. Deploy.

Or from the CLI:

npx vercel        # preview deployment
npx vercel --prod # production

Data model

Plans are data, not components. To add or edit a session, edit lib/plans.ts; to add a movement, add an entry to lib/exercises.ts and reference its key from a plan slot. lib/types.ts documents both shapes. A block declaring an interval spec automatically renders an interval timer.

Storage keys

Key	Contents
ct.active.v2	The in-progress session: plan id, elapsed time, checked slots, skipped blocks, round overrides
ct.history.v2	Last 60 finished sessions
ct.loads.v1	Added weight per hangboard block, last 8 entries each
ct.settings.v1	Preferences, merged over defaults so new settings are not undefined
ct.favorites.v1	Starred exercise keys, newest first, capped at 200
ct.knee.v1	Knee check-ins (day, morning pain, session pain), newest first, capped at 90

Navigation is not stored: it lives in the URL and the browser's history stack, namespaced under a ct key inside history.state so the App Router's own bookkeeping there survives a popstate. Replacing that state wholesale makes Next resynchronize with a full page navigation, which silently reloads the document and discards component state.

Clearing site data resets both. Every key but ct.active.v2 goes into a backup; without one, a cleared browser or a new phone starts from nothing.

Exercise imagery

Illustrations come from free-exercise-db, released into the public domain under the Unlicense. Each entry provides a start and an end frame; the app crossfades them, which reads like a GIF at about 10 KB per frame — 1.7 MB for all 174 frames, small enough to precache entirely for offline use.

Two frames is the ceiling, not a shortcut. All 873 dataset entries have exactly two images — there are no exceptions in the data. wger is unreachable behind some network policies and its imagery is CC-BY-SA rather than public domain; everkinetic is an abandoned migration with no declared license. Generating intermediate frames from two stills would be a cross-dissolve, which is what the animation already does and adds no information. What the dataset does carry, and the app now uses, is a step-by-step instruction list per exercise — bundled for 85 of the 87 illustrated movements and shown in the overlay under the cues.

scripts/exercise-image-map.json maps exercise keys to dataset ids by hand. Automatic name matching produces confident nonsense (it pairs "Barbell Row" with "Barbell Curl"), and an image that teaches the wrong movement is worse than no image, so every pair was checked by eye.

The movements with no illustration are climbing-specific (hangboard grips, limit bouldering, footwork drills) or standing-only variants with no equipment-free match in the dataset — the dataset's calf raise is on a machine and its quad stretch needs a box, which contradicts the whole premise of the standing plans. Most golf and knee rehab movements are missing too: the dataset has no clamshell, Spanish squat, terminal knee extension or club drill, and its split squat is a jump. Leg swings are the one golf match. Those keep their text cues plus a plain web search link. That link deliberately does not point at youtube.com, because Android hands those URLs to the YouTube app.

To regenerate after changing the mapping:

npm i -D sharp && node scripts/fetch-exercise-images.mjs

sharp is only needed to re-run the pipeline, so it stays out of the dependency tree.

Offline behavior

public/sw.js is hand-written rather than generated. The app is one static page plus images, so a build plugin would add coupling without adding capability — and a plugin that breaks on a Next upgrade would take offline support down with it.

• Install precaches the shell and every image listed in public/image-manifest.json.
• Navigations are network-first with a cached shell fallback, so deploys are picked up. Only a successful response replaces the cached shell, so a 404 or a failing deploy cannot become the page that opens offline.
• Everything else is cache-first, which is always correct for content-hashed build assets.

Bump VERSION in public/sw.js when the shell changes in a way that must invalidate caches.