How to build a solo beauty client retention system

June 3, 2026 · 22 min read · back to blog

Most marketing advice for solo beauty pros focuses on acquiring new clients. But for a deposit-first operator with a full booking calendar, retention — specifically, whether a client rebooks and how quickly — is the highest-leverage variable in the business. The difference between a 65% and 80% rebook rate, across 50 active clients, is $100,000–$300,000 in cumulative LTV over three years without adding a single new client. This guide is the operational retention system for deposit-first booth-rental operators: the four levers that determine retention outcomes, the 24–48-hour timing window where most rebook decisions happen, the 90-day dormant client audit, re-engagement sequences that convert 40–60% of clients who've gone quiet, the deposit-retention flywheel that compounds these gains over time, and the three operational mistakes that prevent the system from working.

Why deposit-first operators start with a retention advantage

Before the systems and tactics, it is worth naming why deposit-first operators begin with a structural retention advantage that non-deposit operators do not have.

When a client books through a deposit gate, they have made two commitments before the appointment: they have given you their time, and they have given you financial stake. That dual commitment acts as a filter. Clients who complete a deposit checkout have demonstrated planning orientation — they found your link, chose a service, selected a time, and completed a payment. They did not book impulsively. They are not the client who blocks three slots on three different platforms and cancels whoever confirms last. They are the client who shows up, who has thought about what they want, and who has a realistic expectation of the result.

Empirically, deposit-first operators report:

• 15–25% higher 90-day rebook rates compared to similar non-deposit operators in the same verticals (same city, same service category, similar price point)
• Average booking intervals 1.2–1.5 weeks shorter — clients book their next appointment sooner after a completed visit
• 30–40% lower first-appointment-to-ghost rate — the client who books once and never comes back

The retention advantage is not the system you build — it is the client composition the deposit gate creates. The retention system you build on top of that composition determines whether you extract the full value of that advantage or leave most of it on the table.

The four retention levers

Retention for a solo beauty operator can be broken into four measurable variables. Tracking all four is more useful than tracking any single metric, because they measure different parts of the retention funnel and a problem in one will not always show up in the others.

1. Rebook rate

The percentage of clients who book a subsequent appointment within 90 days of any completed visit. This is the primary retention metric. A healthy rebook rate for a deposit-first operator running a full-service book is 75–85% across the client base. Below 65% consistently indicates a systemic problem in the rebooking funnel — not random churn from individual clients making individual decisions, but something structural: a friction point at booking, a follow-up timing problem, or a service category with an inherent short rebooking cycle that is not being accommodated.

The 90-day window is not arbitrary. For haircut clients (typical interval 4–6 weeks), 90 days represents two missed appointments. For color clients (6–8 weeks), it represents one missed appointment plus drift. For lash fills (2–4 weeks), 90 days is three to five missed fills — at that point, the client has definitively moved on and is in a different category than a delayed rebook. Use 60 days as the rebook-rate window for lash and nail services to match the tighter expected interval.

2. Booking interval

The average number of days between completed appointments for active clients. This varies by service type and individual client:

• Haircuts: 28–42 days (healthy), 43–56 days (stretching), 57+ days (likely churning)
• Color services: 42–56 days (healthy), 57–70 days (stretching), 71+ days (likely churning)
• Lash fills: 14–28 days (healthy), 29–42 days (stretching), 43+ days (likely churning)
• Full lash sets: 56–84 days (healthy), 85–112 days (stretching)
• PMU touch-ups: 180–540 days (highly variable by procedure and individual)
• Nails: 14–21 days (healthy), 22–35 days (stretching)

An increasing booking interval — a client who used to rebook every 5 weeks now booking every 7 weeks — is an early churn signal before the client officially stops rebooking. The client has not left yet, but the relationship is cooling. The increasing interval is detectable before the 90-day rebook-rate threshold is crossed, which gives you time to intervene.

3. Rebook initiation

Whether the rebook was client-initiated (the client reached out or used your booking link unprompted) or operator-prompted (you sent a message asking if they wanted to book). Both types count toward the rebook rate, but they signal different things about the health of the client relationship.

A high ratio of client-initiated rebooks signals strong brand affinity: the client thinks of your service independently of whether you've reminded them. A high ratio of operator-prompted rebooks means the system is working — the prompts are converting — but the client relationship is not self-sustaining. If the prompts stopped, the client would likely not rebook on their own timeline.

Target ratio for a stable book: 60–70% client-initiated. If you are running below 40% client-initiated and above 60% operator-prompted, the underlying client relationship quality is lower than your rebook rate suggests, and you are one missed follow-up sequence away from a significant churn event.

4. LTV per retained client

The annualized revenue from a client who continues to rebook at their typical service interval. Understanding LTV by service type helps you prioritize your retention energy.

• Haircut client, 5-week interval, $80 service: ~10 appointments/yr = $800 LTV
• Color client, 7-week interval, $180 service: ~7.5 appointments/yr = $1,350 LTV
• Balayage client, 10-week interval, $260 service: ~5 appointments/yr = $1,300 LTV
• Full lash set client, 10-week interval, $120 service: ~5 appointments/yr = $600 LTV
• Lash fill client, 3-week interval, $65 fill: ~17 appointments/yr = $1,105 LTV
• Nail client, 3-week interval, $75 service: ~17 appointments/yr = $1,275 LTV
• PMU client, 18-month touch-up, $350 procedure: ~0.7 appointments/yr = $245 LTV

The LTV calculation clarifies priorities. A lash fill client retained for one additional year is worth the same as retaining four haircut clients. A color client retained for an additional year is worth more than retaining two nail clients. Retention energy — follow-up messages, re-engagement sequences, in-chair rebook asks — is finite. Allocate it to the highest-LTV service types first.

LTV also defines the economics of the in-chair rebook ask. When you are looking at a client who just completed a balayage appointment and considering whether to spend 60 seconds offering a specific return slot, you are deciding whether to take an action that, if it succeeds, is worth $1,300 in future revenue. That reframes the ask entirely. It is not a sales interaction — it is a $1,300 decision that takes 60 seconds.

The rebook timing window

The most actionable retention insight for solo beauty operators is that 80% of rebook decisions happen within 24–48 hours of a completed appointment — not 30–45 days later when the client starts thinking about booking again.

The mechanism is straightforward. A client who just left your chair is at peak satisfaction. The service is fresh. The result is visible in the mirror. They have a clear sense of what they want next time. And they have not yet encountered the friction of rebooking — finding the link, choosing a slot, completing the deposit payment, fitting it into their calendar. The rebook decision happens when motivation is at its highest. If you do not capture it in the 24–48-hour window, motivation decays and when the client eventually thinks about booking again, they are re-evaluating from baseline — same as any cold prospect.

The in-chair rebook ask

The in-chair rebook ask is 2–3× more effective than any follow-up message sent afterward. Not because clients feel obligated when they are still in the chair, but because it meets them at the optimal decision moment with zero friction. The conversation has reached its natural endpoint, you are finishing up, and the question is service continuity rather than a sales pitch.

What works:

• "Do you want to go ahead and lock in your next one while you're here? I have [specific date + time] in [N] weeks."
• "Your color is going to want a touch-up around [date range]. I have [specific slot] open — want to get it on the calendar now?"
• "I know lash fills sneak up fast. I have [date] open in three weeks if you want to hold it."

What does not work:

• "You should book your next appointment soon — I fill up fast." (generic urgency, no specific offer)
• "I'll send you a reminder next month." (deferred, puts action on you, removes the moment)
• "Let me know when you want to come back!" (open-ended, returns the decision entirely to the client)

The specific-slot offer is the key variable. Clients who are asked "want to lock in Tuesday the 14th at 2pm?" book at 3–4× the rate of clients asked "want to book your next appointment?" The specificity removes decision friction — the client only needs to say yes, not choose a time, consider their schedule, weigh competing options, or remember to do it later. The cognitive work is done. All they are deciding is yes or no.

For services with tight rebooking cycles — lash fills (2–3 weeks), nail maintenance (3 weeks), haircuts for clients who like their length close — the in-chair rebook ask should be the default close to every appointment. Not occasionally. Not when you remember. Every appointment.

For services with long rebooking windows — PMU touch-ups (12–18 months), seasonal balayage — the in-chair close takes a different form: "I'll reach out in [month] with a link when you're getting close to touch-up time." This is not the same as saying "let me know when you're ready" — it commits you to a follow-up action and names a timeline. The client leaves knowing what to expect.

The 24-hour follow-up message

For clients who did not rebook in the chair — they had to check their schedule, they left quickly, the moment passed — the follow-up message sent within 24 hours is the highest-leverage operator-prompted touchpoint. After 48 hours, conversion on a rebook prompt drops by 40–60%. After 72 hours, it is at baseline — the same conversion rate as a cold rebook message sent on a fixed monthly schedule.

Template for haircut or color clients:

"Hey [Name], great seeing you today! How's the [color / cut] feeling? I have [Tuesday X] or [Wednesday Y] open in [N] weeks if you want to lock in now — just use the link in my bio."

What this message does correctly:

• Opens with a service check-in (not a booking request) — signals you care about the result, not just the next appointment
• Provides two specific dates (not "reach out when you're ready")
• Points to the booking link (removes the friction of the client asking for it)
• Does not mention the deposit — the deposit is handled at checkout; priming the client to think about it before they open the link is unnecessary friction

Template for lash fill clients:

"Hey [Name], glad the set is looking great! Fills usually want to happen around 3 weeks — I have [date] open if you want to get it on the calendar before I fill up."

The mention of a specific service timeline ("fills usually want to happen around 3 weeks") is functional for lash clients who are still learning their service cadence. It sets the expectation and frames the booking prompt as care rather than a sales message.

Timing logistics: send the follow-up on the same day as the appointment, ideally 3–5 hours after the appointment ends (not immediately after — a message that arrives while the client is still in their car signals automated behavior rather than genuine outreach). For evening appointments, send the following morning.

The 90-day rebook audit

Even with consistent in-chair asks and timely follow-up messages, some clients will go quiet. Life changes, schedule shifts, a competing offer that landed at the right moment, or simply forgetting. The 90-day rebook audit is the quarterly system for identifying who those clients are and running a re-engagement sequence that converts 40–60% of them back onto your calendar.

Who to audit

The audit list is clients who:

• Have completed at least one appointment (exclude first-time bookings that ghosted before the appointment — those are a separate no-show segment)
• Have not made a new booking within 90 days of their last completed appointment (60 days for lash and nail clients)
• Are outside the expected rebook window for their service type — a PMU client who hasn't booked in 90 days may be entirely on schedule

For color clients (typical interval 42–56 days), being 90 days post- appointment means they are 5–7 weeks past their expected rebook date. That is enough distance to confirm the delay is not a scheduling coincidence. For haircut clients (28–42 day interval), 90 days means 6–8 weeks past expected. That cohort is likely to be reachable but drifting.

Exclude clients who cancelled after the refund window in the period before they went quiet — they may have had a negative experience and re-engagement should start with a check-in on the service outcome, not a direct booking prompt.

The re-engagement sequence

Message 1 — Personal check-in (90 days post-appointment for color/cut, 60 days for lash/nail):

"Hey [Name], hope you're doing well! It's been a while since I've seen you — how has your [service] been holding up? I have some openings in the next couple of weeks if you want to get back on the calendar. Here's the link: [booking link]"

This message frames the outreach as a check-in, not a promotional push. "How has your [service] been holding up?" is service-oriented — it signals you remember what they had done and are interested in the result, not just the booking. The link at the end is low-pressure: it is there if they are ready, not a demand. Expected conversion from Message 1 across the 90-day audit list: 35–45%.

Message 2 — Specific-slot offer (7 days after Message 1, if no response or no booking):

"Hey [Name], I have [specific date + time] open coming up — would that work for you? I can hold it for you if you want to book now."

The specific-slot offer converts significantly better than a second open-ended check-in. The urgency is real — you have a specific slot you are offering — not manufactured. Expected conversion from Message 2 on the non-responding cohort after Message 1: 15–20%. Combined, Messages 1 and 2 re-engage 50–60% of the 90-day dormant list.

Clients who do not respond to Message 2 are either churned (moved to a different operator, changed their service habits, became price-sensitive) or will return when they are personally ready without operator prompting. A third message in the same sequence has diminishing returns and risks pushing a dormant client toward an explicit opt-out response — which is a worse outcome than quiet drift, because it closes the door entirely. Stop at two messages per re-engagement cycle.

Seasonal re-engagement variation

A re-engagement campaign framed around a service addition or skill update can reactivate dormant clients without the awkwardness of "you haven't been in":

"Hey [Name], I've been adding some new services for spring — [technique or service addition]. Let me know if you want to book a [service type] before my April slots fill up. [booking link]"

This message works because it gives the client a reason to re-engage independent of the lapsed time. Something has changed, which makes the outreach forward-looking rather than backward-looking. It works especially well for clients who went quiet due to price sensitivity or scheduling friction, not dissatisfaction — they may have been looking for a reason to come back.

Seasonal re-engagement windows that typically produce the highest conversion: late January / early February (post-holiday reset, clients thinking about spring), late August / early September (back-to-school schedule regularization), and mid-October (pre-holiday service catch-up). These windows correspond to the moments in the year when people's schedules and attention are naturally resetting — high motivation to re-establish routines.

The deposit-retention flywheel

The most durable retention outcome for a deposit-first operator is not a well-executed sequence of follow-up messages — it is a client base that self-reinforces the behavior you want. The deposit-retention flywheel describes how this happens:

1. The deposit gate filters for higher-commitment clients at the point of booking. Clients who complete the deposit checkout have self-selected for planning orientation and financial commitment — they are not the impulsive or low-stakes booker.
2. Higher-commitment clients have stronger first-appointment outcomes. They have thought about the appointment in advance. They have clearer expectations. They are less likely to be disappointed by a result they did not anticipate. Their satisfaction scores — and their in-chair rebook response — are higher.
3. Higher first-appointment satisfaction produces higher in-chair rebook rates. The timing-window effect (peak-satisfaction rebook opportunity in the 24–48 hours after the appointment) is amplified when the satisfaction is genuine rather than politely expressed.
4. Higher rebook rates build a denser, more stable client calendar. Fewer emergency-fill slots. More predictable revenue. Lower week-to-week revenue variance. These outcomes reduce the operational stress that leads to quality inconsistency.
5. Operational stability allows you to invest in the service experience: better products, cleaner consultation time, continued skill development. The feedback loop is virtuous — a less stressed operator delivers more consistent services.
6. Consistent service experience drives client-initiated referrals, which is the highest-quality acquisition channel for a deposit-first operator. Referred clients come pre-qualified: their referrer has explained the deposit requirement, they know what to expect, and they share a demographic and behavioral profile with the referrer.
7. Referral-acquired clients enter the funnel through the same deposit gate and undergo the same commitment filter. The next-generation client composition is maintained.

This is a flywheel because each step reinforces the next. But it operates only if the deposit gate is consistently applied. The wheel breaks down when the operator creates exceptions to the deposit requirement — special accommodations for referred clients, for regulars who ask, for high-value clients who push back. Each exception introduces a lower-commitment client into a book that was previously filtered. The effect is not dramatic in the short term, but it is cumulative: the client composition drifts, rebook rates drift, and the flywheel gradually loses its velocity without any single identifiable cause.

What the flywheel looks like in practice

A deposit-first solo colorist with a well-functioning flywheel will show these characteristics within 12–18 months of consistent operation:

• 75–85% rebook rate across the active client base
• Referral-sourced new clients representing 30–50% of new client acquisition (vs 10–20% for non-deposit operators in the same market)
• No-show rate below 5% across all service types
• Booking horizon consistently 6–8 weeks (demand exceeds supply at current pricing)
• Revenue variance below 15% week over week (stable forward bookings)

The 6–8 week booking horizon signal is particularly important and frequently misread. When the flywheel is operating, the correct response to a consistently long booking horizon is not to open more appointment slots — it is to raise prices, because you are below market-clearing price for your current demand level. A deposit-first operator with a 10-week booking horizon who adds evening slots is solving the wrong problem. They are adding supply to a demand-constrained situation when the better lever is increasing price until the booking horizon compresses to 6–8 weeks.

ChairHold integration for retention

The ChairHold features that directly support the retention system:

Booking links for rebook prompts

When sending the in-chair rebook ask by message or the 24-hour follow-up, the link should be your standard service booking link with the configured deposit percent. Do not create a special "no deposit for repeat clients" link. The deposit is part of what maintains the commitment filter for returning clients — it is not only a screening tool for new clients. Returning clients who have paid deposits before understand the system. Special exemptions for repeat clients undermine the policy consistency that makes the deposit meaningful and signal that the deposit requirement is negotiable.

If a long-term regular expresses friction about the deposit on a rebook, the response is not to remove the deposit — it is to acknowledge the friction and explain what the deposit does for the relationship:

"I know it's an extra step — but the deposit is what lets me protect your slot and keep my schedule predictable for everyone who books. It goes toward your service either way."

This framing reorients the deposit from "a fee I'm charging you" to "a system that protects you as a repeat client." Most regulars who express friction accept this explanation because it is accurate.

time_to_live_hours for specific-slot offers

When making a specific-slot offer to a dormant client (Message 2 in the re-engagement sequence), you can create a booking link with a shorter time_to_live_hours — 4–6 hours rather than the standard 24h. This creates a soft deadline that matches the urgency of the specific- slot offer: "I can hold it for you if you book now" is more credible when the link expires in 6 hours than when it remains open for 24 hours.

The 24h default TTL is correct for all standard outbound booking communications. The shorter TTL is appropriate specifically for specific-slot offers where you want to communicate real, not manufactured, urgency.

Waitlist for retention-triggered fills

When a retained client cancels within the booking window, the waitlist blast fills the vacated slot — and the best candidate for that slot is often a client from your 90-day dormant list who received Message 1 within the past week and is likely to respond to an immediately available slot. This is the retention system interacting with the cancellation management system: the dormant client gets a high-priority slot, the cancellation cost is minimized, and a client who might have remained dormant returns to the calendar. The conversion rate for waitlist blasts to dormant clients who have recently been re-engaged is 2–3× higher than for cold waitlist contacts, because the re-engagement message primed intent.

To make this work operationally, maintain a mental (or written) note of which dormant clients have received Message 1 recently. When a same-day or next-day cancellation arrives, add those clients to the waitlist blast manually or reach out directly before the general waitlist blast goes out.

Three operational retention mistakes

Mistake 1: Discounting to retain clients who are signaling churn

When a client starts cancelling more frequently or extending their booking interval, the instinct for many operators is to offer a discount as a retention lever. This is consistently counterproductive.

Discounting attracts price-motivated behavior from the client who stays because of the discount, not because of service value. It establishes a precedent: the client learns that signaling churn produces a discount. Future churn signals become a negotiating tactic. It also introduces a new client profile — the discount-motivated client — into a book that was filtered by the deposit gate for commitment-oriented clients. These two profiles have different retention rates, different rebook frequencies, and different referral behaviors. Discounting to retain one client degrades the composition of the book if the behavior becomes a pattern.

The correct retention response to a churning client is a direct service quality check-in:

"Hey [Name], I noticed it's been a while — is there anything I should know about or do differently when you come in next time?"

This message either identifies a fixable service problem (technique feedback, scheduling inconvenience, product reaction) or gracefully confirms the client has moved on for reasons outside your control (price, location, personal circumstances). Both outcomes are better than discounting: the first recovers the client through improved service, the second removes the cost of retention effort on a client who has already decided to churn.

Mistake 2: Sending rebook prompts on a fixed schedule, not a service-interval schedule

A common error is sending rebook reminders on a fixed monthly schedule — the first Monday of every month, a quarterly broadcast to all clients — rather than on each client's individual service interval. For a haircut client who should rebook every 4–5 weeks, a monthly prompt that arrives 6 weeks after their last appointment is acceptably timed. For a lash fill client who should rebook every 2–3 weeks, a monthly prompt arrives 2–3 weeks after the client should already have booked — you have missed the optimal window entirely.

The retention system needs to be calibrated to service type, not to a one-size-fits-all broadcasting cadence. For a solo operator managing a client base of 40–80 active clients across two or three service categories, this does not require software automation — it requires a simple habit of noting the expected rebook date for each completed appointment and sending the follow-up message when the client's specific window arrives, not on a generic schedule.

The easiest implementation: after each appointment, estimate the expected rebook date (last appointment date + typical service interval) and make a note. When that date arrives and the client has not self-rebooked, send Message 1 of the re-engagement sequence. This is the service- interval-aware retention system; it does not require tracking software beyond whatever note-taking system you already use.

Mistake 3: Over-indexing on re-engagement, under-investing in the in-chair ask

The 90-day re-engagement sequence is a recovery mechanism — it is what you do when the primary retention system did not fire. If you are running the re-engagement sequence on 40% of your client base every quarter, the problem is not that the re-engagement system is failing. The problem is that the in-chair ask is not happening consistently.

The re-engagement sequence costs time, requires effort, and recovers 50–60% of the dormant cohort under good conditions. The in-chair ask, applied consistently, would have retained most of those clients at the natural close of their appointment — before they became dormant. The ROI comparison: an in-chair ask requires 60 seconds and converts at 50–70% with zero follow-up required. A re-engagement sequence requires two messages, 7–10 days, and converts at 50–60% under optimal conditions (worse if significant time has passed, if the client has found a competing operator, or if the dormant client list has grown too large to manage personally).

If your quarterly re-engagement list is consistently large, diagnose the in-chair ask first. The fix is not a better message template for the re-engagement sequence — it is a behavioral protocol: at the end of every appointment, before the client puts on their coat, offer a specific return slot. That single habit change outperforms any re-engagement campaign you can design.

Quarterly retention health check

Run the following review once per quarter to calibrate the retention system:

1. Rebook rate check. Pull all completed appointments in the last 90 days. What percentage resulted in a new booking within 60 days? If below 65%, break down by service type — is the shortfall universal or concentrated?
2. Booking interval trend. For your 20 most active clients, compare average days between appointments this quarter vs last quarter. An increasing interval is a churn signal even if the client is still rebooking.
3. Dormant list size. How many clients completed an appointment 90+ days ago and have not rebooked? If this number is growing quarter over quarter, the primary retention system (in-chair ask + follow-up) is not keeping pace with new client acquisition rate.
4. Rebook initiation ratio. Of rebooks in the last 90 days, what percentage came in via the booking link without a prior operator message? Track this directionally over time.
5. LTV by service type. Calculate annualized LTV for your top three service types. Which service type's retained clients represent the highest total annual revenue? Allocate retention energy proportionally.

Quick-reference checklists

Post-appointment retention (run after every appointment)

• In-chair rebook ask: offered a specific slot before the client left? (Y/N)
• If yes and client did not rebook: 24-hour follow-up message sent? (Y/N)
• If no in-chair ask (client left quickly): message sent within 6 hours? (Y/N)
• Expected rebook date noted for this client's service interval? (Y/N)

90-day dormant list re-engagement (run quarterly)

• Pulled list of clients 90+ days post-appointment with no new booking (60 days for lash/nail)
• Excluded PMU and seasonal service clients within their normal window
• Excluded recent cancellation-after-window clients (different outreach approach)
• Message 1 (check-in + link) sent to full dormant list
• Message 2 (specific-slot offer) sent 7 days later to non-responders
• New rebooks logged against the dormant list conversion rate
• Clients still non-responsive after Message 2 moved to inactive status

Flywheel health diagnostic (run quarterly)

• Rebook rate ≥75%? If not, identify by service type.
• Booking horizon 6–8 weeks? If longer, consider price adjustment before opening more slots.
• New client acquisition: what percentage from referrals? Target 30%+.
• No-show rate ≤5%? If higher, revisit deposit percent by service category.
• Deposit requirement applied consistently across all client types, including returning clients?

Related guides

• CAC vs LTV for solo beauty pros — the full economics of client acquisition cost vs lifetime value by vertical, with the breakeven analysis that shows why retention is 4–7× more valuable per dollar than acquisition for a mature booth-rental operator.
• How to set up a referral program as a solo beauty pro — the referral system that converts your highest-LTV retained clients into your most effective acquisition channel, with message templates and referral incentive structures that preserve deposit-first client composition.
• How to handle client cancellations as a solo beauty pro — the complete cancellation management playbook that shows how cancelled clients re-engage with a 45–65% rebook rate when handled correctly — one of the fastest routes back onto your calendar for a dormant client.
• How to price your solo beauty services with deposit in mind — the pricing framework that shows how a correctly calibrated deposit percent interacts with rebook rate to produce a higher effective hourly rate — the retention system and the pricing system are not independent.
• How to set your booking schedule as a solo beauty pro — the schedule design guide covering advance booking window, buffer time by service type, and the seasonal schedule adjustments that reduce cancellation frequency and increase the in-chair rebook opportunity.
• ChairHold setup in 10 minutes — how to configure deposit_percent, refund_window_hours, and time_to_live_hours for each service type — the settings that directly determine the commitment filter that the retention flywheel depends on.