Status: this integration is built and tested but not yet switched on for everyone. It goes live in a private beta first, then to everyone once the Intervals.icu app is approved and listed. Nothing on this page describes something Pheidi does today without your explicit connect.

What it does

Pheidi builds a deterministic, research-based 5K to marathon plan and rebuilds it around your real week. Intervals.icu is a training calendar and analysis workbench that already talks to Garmin, COROS, Suunto, Wahoo, Amazfit and Huawei. Connecting the two means Pheidi writes your upcoming runs to your Intervals.icu calendar, and Intervals.icu delivers them to whichever devices you have connected there.

Pheidi remains the source of truth for what the plan is and why a session changed. Intervals.icu remains the source of truth for device delivery, completed activities, and any edit you make on its calendar. Pheidi is not a chat coach and does not become one by connecting: the plan is the same rule-based plan, just delivered to more places.

What gets written

The next two weeks of pending runs, as planned workouts. Each one carries a title ("Intervals — 6.0 mi"), the date, an estimated duration and distance, and the session written in Intervals.icu's own workout-builder text, for example:

Warmup
- Warm up 10m

Main Set 6x
- hard 800mtr 7:05/mi Pace
- recovery 2m

Cooldown
- Cool down 10m

Intervals.icu compiles that text into device steps. Pace targets come from your VDOT paces in Pheidi; runners on effort-based (RPE) pacing get the effort cue instead of a pace. Rest days, cross-training and strength are not written. Past sessions are never written or changed, and nothing about you (name, email, heart rate, health data) is included in the events.

When it syncs

  • Right after you connect.
  • Whenever you open Pheidi (at most every half hour), so what you see and what your watch gets never drift for long.
  • Whenever your plan changes in Pheidi: a logged run, a vacation, an injury, a manual edit, an automatic adjustment, a regenerated plan.
  • When you press Sync now in Settings.
  • On a timer, as a safety net, a few times a day.

Every sync reads your calendar back first, so it never writes blind. You can press Preview changes to see exactly what the next sync would add, update or remove before it happens. When you regenerate a plan, the new sessions are written before the old ones are removed, so your calendar is replaced rather than emptied. While a plan is paused, nothing is touched. If you archive or finish a plan without starting another, the upcoming Pheidi workouts are removed from your calendar like any other session that left the plan; past ones always stay.

Your edits on Intervals.icu win

If you change a Pheidi-written workout on Intervals.icu (move it, rewrite the steps, retitle it), Pheidi notices on the next sync and leaves it alone. Settings shows it as an edited workout with two choices: Keep my Intervals.icu edit (Pheidi stops managing that one for good) or Replace with Pheidi's version (an explicit, one-time overwrite). Pheidi never overwrites an edit silently. If you delete a Pheidi workout on Intervals.icu, it stays deleted; a new plan creates new sessions, which is the only way it comes back.

Pheidi only ever touches events it created itself. Workouts from other apps, or ones you added by hand, are invisible to it even if they land on the same day.

Completed runs flowing back (optional)

Separately, and only if you switch it on, Pheidi can read your Intervals.icu activity summaries (date, distance, moving time, heart rate) and mark the matching plan run done. It prefers the pairing Intervals.icu already made between a workout and an activity; otherwise it needs a single confident match on the same day. Two similar runs on one day are left for you to log by hand rather than guessed. A run you already logged yourself is never overwritten. Pheidi reads summaries only: no GPS streams, no files, and it never uploads or edits activities on Intervals.icu.

Activities that reached Intervals.icu from Strava are not available through this path (Intervals.icu does not expose them to apps). If Strava is where your runs live, use Pheidi's own Strava sync for completions, and keep Intervals.icu for the calendar. Connect one primary device path to Intervals.icu so a run is not recorded twice.

Devices: what to expect, honestly

Pheidi writes your plan to Intervals.icu; Intervals.icu delivers to the devices you have connected there. Coverage and how much structure arrives depend on that connection, not on Pheidi. In Intervals.icu go to Settings → Connections, connect your watch brand, and enable Upload planned workouts (the wording varies by vendor). Community-reported behaviour as of September 2026, which you should re-check for your own device:

  • Garmin receives roughly the next week of planned workouts. Pace targets can be dropped if your Intervals.icu Run sport settings have no threshold pace, so set one there. Some runners report needing to delete and recreate an event before Garmin picks up a change.
  • COROS receives planned workouts; mixed pace-and-heart-rate steps have known mapping quirks.
  • Suunto uses SuuntoPlus Guides for the next week; steps must be valid workout text, which is what Pheidi writes.
  • Wahoo planned-workout support has been described as beta; time-zone mismatches are a known pitfall.
  • Amazfit / Zepp planned workouts were announced for recent models, next week only.
  • Huawei takes the next planned run in the coming week, one at a time.

Pheidi does not certify any of these paths and shows no vendor logos as if it did. The FIT file export remains available for any watch, with or without Intervals.icu.

Privacy and disconnecting

Connecting asks Intervals.icu for calendar write access, plus activity read only if completion sync is offered and you keep that box ticked. Pheidi stores a single encrypted access token and a small table mapping each of your sessions to the calendar event it wrote. It stores no secrets in logs and never shows the token in any admin tool.

Disconnect in Settings revokes Pheidi's access at Intervals.icu (which also stops Intervals.icu sending Pheidi any webhooks about you) and deletes the token and mapping here. Your Intervals.icu calendar is left exactly as it is. If you also want Pheidi's upcoming workouts removed from that calendar, tick the box before disconnecting; Settings shows how many it would remove. Past and completed workouts are never removed. Deleting your Pheidi account does the same revoke.

Try it in the app

Once the beta opens, connect from Settings → Intervals.icu in the Pheidi app at app.pheidi.training.

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