Review of Spark's trust model

Unilateral-exit readiness

A 100,000-sat mobile balance expanded into 253 ordered packages, and 252 failed the naive first submission

Blink's published 100,000-sat wallet contained 22 leaves and 253 root-to-leaf package steps. When all packages were first submitted together, 252 were rejected because the transaction graph could not enter the mempool in that form. 1

1 sourceEvidence reviewed through July 14, 2026

What the evidence shows

Technical and product details

  1. Documented behavior

    Blink's published mainnet wallet contained 22 leaves and 253 root-to-leaf package steps. 1

    Supporting material shown on this page

    Blink mainnet case studyPinned source code · github.com · checked 2026-07-14
    Relevant lines from the pinned source · open raw file
    1# Case study: a real Spark unilateral exit on Bitcoin mainnet
  2. Observed result

    The first attempt submitted all packages; 252 were rejected with TRUC descendant-policy or missing-input errors. Only the root package could enter. 1

    Supporting material shown on this page

    Blink mainnet case studyPinned source code · github.com · checked 2026-07-14
    Relevant lines from the pinned source · open raw file
    1# Case study: a real Spark unilateral exit on Bitcoin mainnet
  3. Reason recorded by the experiment

    Each deeper package depended on ancestors not yet confirmed, so the tree had to be advanced sequentially. 1

    Supporting material shown on this page

    Blink mainnet case studyPinned source code · github.com · checked 2026-07-14
    Relevant lines from the pinned source · open raw file
    1# Case study: a real Spark unilateral exit on Bitcoin mainnet
  4. Product consequence

    A generic “broadcast transactions” button is not a workable implementation of the actual graph. 1

    Supporting material shown on this page

    Blink mainnet case studyPinned source code · github.com · checked 2026-07-14
    Relevant lines from the pinned source · open raw file
    1# Case study: a real Spark unilateral exit on Bitcoin mainnet

Scope control

What this does not establish

  • Blink reports the off-chain rejection count for this particular 22-leaf wallet. The blockchain independently shows accepted transactions, but not every rejected package submission; other wallets can have smaller or differently shaped graphs. 1

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.

1

Blink mainnet case study

Pinned source code · github.com · Pinned or archival · checked 2026-07-14

Open original source

How sources, absence findings, and limitations were evaluated