A Connect IQ widget with a glance that brings your intervals.icu fitness data to round-screen Garmin watches. Built for and tuned on the Fenix 8 Pro MicroLED (fenix8pro47mm, 454×454, API 6.0); supports 66 device IDs across the Fenix 7/8/9/E, Epix 2, Forerunner, Venu, MARQ 2, Descent, Approach and Instinct 3 AMOLED families (layouts scale with screen size; MIP models render the chart palette with fewer colors).

Glance	Form	Load (polar)

HRV ring	Ramp rate ring	Recovery tiles

More: eFTP · steps · sleep · body · fuel

• Glance — a compact banded CTL/ATL chart (the form-zone colors at a glance) with the current form value and data age, right in the widget carousel.
• Form page — big TSB value with zone label, plus Fitness / Fatigue / Ramp rate.
• Polar load chart — CTL and ATL wrapped around the bezel over the time-varying form-zone bands (transition / fresh / grey / optimal / high-risk), computed per angle step from interpolated CTL. The display range auto-fits the data and band envelope; labeled value arcs and 30-day spokes keep it readable. Every graph page can render round (radial) or rectangular, per page.
• Four configurable graph pages — each picks the load chart or one of 17 metrics: HRV (rMSSD/SDNN), resting/sleeping HR, ramp rate, eFTP, weight, body fat, VO2max, sleep score/hours, readiness, steps, SpO2, respiration, Baevsky stress index, calories. Radial bar rings (newest day highlighted) or auto-scaled line charts with gap handling for sparse data; HRV charts add a personal baseline band with deviation-colored bars.
• Interactive zoom — START on any graph page shows +/- controls beside the UP/DOWN buttons: zoom the window between 7 and 90 days, rescaling instantly from cached data (works offline). Narrow windows render as smooth interpolated curves.
• Four configurable data pages — form, recovery, sleep, body, fuel, subjective wellness or status, rendered as a modern tile grid with vector fonts auto-fitted to their space (no clipped or colliding text on the round display).
• Status page — last sync, athlete, auth method, errors.
• Watch-face complication — a single complication, "Intervals data", carrying fitness/fatigue/form as one string (31/15/+16), for any watch face that supports Connect IQ complications, or Face It. Refreshed by the background sync; follows the "Form as %" setting. This is a watch-face complication, not an activity data field.
• Sync — event-driven rather than clock-driven: a background service syncs ~45 min after you wake and ~20 min after an activity finishes (giving the data time to reach intervals.icu via Garmin Connect), with a ~6 h safety net, every delay jittered per watch. Opening the widget refreshes data older than 2 hours; START forces a sync. A normal sync is a single request for yesterday and today — around five requests per day.

• A free intervals.icu account. Link it from the watch (press START on first run — OAuth consent opens on your phone via Garmin Connect). An API key (intervals.icu → Settings → Developer Settings) still works as a legacy fallback, but is deprecated and will be removed in v1.0.
• Garmin Connect IQ SDK ≥ 6 (built with 9.2) and a Java runtime (brew install --cask connectiq and brew install openjdk on macOS).
• Device files for fenix8pro47mm, downloaded once via the Connect IQ SDK Manager (brew install --cask connectiq-sdk-manager, requires a free Garmin developer login).

./build.sh                  # debug build -> bin/intervals-widget.prg
./build.sh --release
DEVICE=fr955 ./build.sh     # debug build for another supported device
./build.sh --export         # beta store package (beta app ID)
./build.sh --export-prod    # production store package (its own app ID,
                            # since each store listing needs a unique one)

The script locates the SDK (Homebrew cask or SDK Manager install), generates a signing key on first run, and — if a git-ignored .apikey file exists in the repo root — bakes its contents in as the default apiKey property so a sideloaded build needs no further configuration:

echo -n "your-intervals-api-key" > .apikey   # optional, never committed

Without .apikey the key must be set in the app settings (Connect IQ phone app for store installs, or the simulator's settings editor).

Connect the watch via USB (MTP — use Android File Transfer or OpenMTP on macOS) and copy bin/intervals-widget.prg into /GARMIN/Apps/. Restart the watch; the glance appears in the carousel.

The chart time window is not a setting — zoom it live with START then UP/DOWN on any graph page.

SDK=~/Library/Application\ Support/Garmin/ConnectIQ/Sdks/connectiq-sdk-mac-*
$SDK/bin/connectiq                                  # start simulator
$SDK/bin/monkeydo bin/intervals-widget.prg fenix8pro47mm

Set the API key via File → Edit Persistent Storage → Edit Application.Properties, and trigger a background sync with Simulation → Background Events → Temporal Event. Note the simulator preserves app settings across reinstalls — delete GARMIN/APPS/SETTINGS/INTERVALS-WIDGET.SET from the simulator's temp filesystem if changed property defaults don't seem to apply.

Authentication is OAuth2 (scope WELLNESS:READ): the watch opens the consent page through Garmin Connect Mobile, and a small Cloudflare Worker (worker/) exchanges the one-time code for a long-lived bearer token — the client secret never ships in the app. Legacy API keys still work via HTTP Basic (username API_KEY) until v1.0; existing key users see a gentle relink nudge every 14 days.

Every request has the same shape: GET /api/v1/athlete/{id}/wellness over a date window, with a fields= filter (which also strips nulls, keeping payloads small for the watch) covering the union of the tile metrics and the selected chart metrics.

Because past wellness days are immutable, a normal sync asks only for yesterday and today — one request — and merges the result into a local cache; the tile values are the most recent non-null reading within the last 7 cached days. The window widens automatically after time offline, and wide fetches are split into ≤30-day chunks (a 90-day response with sportInfo exceeds the watch's response buffer). A fresh cache loads 30 days of history; the older 60 are fetched once, only if you zoom past 30 days.

Form (TSB) is computed as ctl − atl. The zone coloring and chart bands use absolute TSB thresholds (+20 / +5 / −10 / −30) by default, matching intervals.icu's coloring; the "Form as % of fitness" setting switches both the displayed value and the zone scale to percent-of-CTL, matching the equivalent intervals.icu option. eFTP comes from the wellness sportInfo array (first sport entry).

Please be polite to the API — the widget averages about five requests per day per user, which is well within what the intervals.icu folks ask of clients.

MIT