Higher fee rates push more Spark leaves below the economic exit threshold

What the evidence shows

Technical and product details

1. Per-leaf test

   Blink compares each leaf's value with the CPFP fees for its entire exit chain plus its final sweep. 1

   Supporting material shown on this page

   Blink per-leaf economicsPinned source code · github.com · checked 2026-07-14

   90Four leaves (32,768 + 32,768 + 16,384 + 8,192 sats) held 90% of the balance.
   91The other 18 — dust from routine wallet activity, some as small as 1 sat —
   92would each have cost 2,100–4,600 sats to exit: exiting everything would have
   93spent ~77.5k sats in fees to recover 100k. The tooling now computes this per
   94leaf and skips uneconomical leaves by default (`INCLUDE_UNECONOMICAL=1`
   95overrides; the economics math is regression-tested against this very bundle,
   96adapted to regtest, in

2. Scaling mechanism

   As the fee rate rises, those transaction costs rise while the leaf's value does not. 12

   Supporting material shown on this page

   Blink per-leaf economicsPinned source code · github.com · checked 2026-07-14

   90Four leaves (32,768 + 32,768 + 16,384 + 8,192 sats) held 90% of the balance.
   91The other 18 — dust from routine wallet activity, some as small as 1 sat —
   92would each have cost 2,100–4,600 sats to exit: exiting everything would have
   93spent ~77.5k sats in fees to recover 100k. The tooling now computes this per
   94leaf and skips uneconomical leaves by default (`INCLUDE_UNECONOMICAL=1`
   95overrides; the economics math is regression-tested against this very bundle,
   96adapted to regtest, in

   Blink fee-rate sensitivityPinned source code · github.com · checked 2026-07-14

   125Bottom line: **89,668 of 100,000 sats (~90%) reach the destination.** The
   126all-in cost of the exit is ~18,700 sats — 9,888 abandoned as dust, 8,388 in
   127CPFP fees, 444 in sweep fees — plus the on-chain fee for the transaction that
   128funded the CPFP address in the first place. At higher fee rates every term
   129scales up and more leaves fall below the economic threshold; at 10 sat/vB this
   130wallet would abandon two more leaves and pay ten times the fees on the rest.

3. Selection consequence

   More leaves can become uneconomical to recover, so the tool skips them by default unless the user explicitly overrides that behavior. 123

   Supporting material shown on this page

   Blink per-leaf economicsPinned source code · github.com · checked 2026-07-14

   90Four leaves (32,768 + 32,768 + 16,384 + 8,192 sats) held 90% of the balance.
   91The other 18 — dust from routine wallet activity, some as small as 1 sat —
   92would each have cost 2,100–4,600 sats to exit: exiting everything would have
   93spent ~77.5k sats in fees to recover 100k. The tooling now computes this per
   94leaf and skips uneconomical leaves by default (`INCLUDE_UNECONOMICAL=1`
   95overrides; the economics math is regression-tested against this very bundle,
   96adapted to regtest, in

   Blink fee-rate sensitivityPinned source code · github.com · checked 2026-07-14

   125Bottom line: **89,668 of 100,000 sats (~90%) reach the destination.** The
   126all-in cost of the exit is ~18,700 sats — 9,888 abandoned as dust, 8,388 in
   127CPFP fees, 444 in sweep fees — plus the on-chain fee for the transaction that
   128funded the CPFP address in the first place. At higher fee rates every term
   129scales up and more leaves fall below the economic threshold; at 10 sat/vB this
   130wallet would abandon two more leaves and pay ten times the fees on the rest.

   Blink economics takeawayPinned source code · github.com · checked 2026-07-14

   202   100k-sat wallet. With economic triage, ~90% of the balance reached the
   203   destination. Self-custody on Spark is real, but the exit path is expensive
   204   and slow by construction; size expectations accordingly.
   2052. **Dust leaves are a liability.** 18 of 22 leaves were not worth exiting at
   206   even 1 sat/vB. Wallets should consolidate leaves while operators are
   207   cooperative, and exit tooling must triage by economics rather than exit
   208   everything blindly.

4. Protocol/economic distinction

   Such leaves remain part of the wallet state but are omitted from the economically selected on-chain recovery path. 13

   Supporting material shown on this page

   Blink per-leaf economicsPinned source code · github.com · checked 2026-07-14

   90Four leaves (32,768 + 32,768 + 16,384 + 8,192 sats) held 90% of the balance.
   91The other 18 — dust from routine wallet activity, some as small as 1 sat —
   92would each have cost 2,100–4,600 sats to exit: exiting everything would have
   93spent ~77.5k sats in fees to recover 100k. The tooling now computes this per
   94leaf and skips uneconomical leaves by default (`INCLUDE_UNECONOMICAL=1`
   95overrides; the economics math is regression-tested against this very bundle,
   96adapted to regtest, in

   Blink economics takeawayPinned source code · github.com · checked 2026-07-14

   202   100k-sat wallet. With economic triage, ~90% of the balance reached the
   203   destination. Self-custody on Spark is real, but the exit path is expensive
   204   and slow by construction; size expectations accordingly.
   2052. **Dust leaves are a liability.** 18 of 22 leaves were not worth exiting at
   206   even 1 sat/vB. Wallets should consolidate leaves while operators are
   207   cooperative, and exit tooling must triage by economics rather than exit
   208   everything blindly.

Scope control

What this does not establish

• This is an economic threshold, not a cryptographic failure or a claim that every leaf becomes unrecoverable. It depends on fee rate, leaf value, chain depth, and any prior consolidation. 123

Sources and excerpts

Primary sources

The relevant details and available source-code excerpts appear alongside the claims above. This list preserves the complete original-source trail for independent verification.