[Mirksen]

Warum

The fee market, Merkle proof and signed-payment validation already work, but the guided track never teaches them. Learners need to observe both successful inclusion and the limits of redoing proof of work.

Was

Append three missions: confirm a waiting low-fee payment with its higher-fee child, verify and alter a Merkle proof, and tamper with a signed payment before re-mining it. Completion uses actual template, accepted-block and verification results. The signature experiment uses the newest block because existing ledger guards correctly forbid repairing descendants of an invalid signature; every hash and link can be correct while the payment remains invalid. Ledger rules, dependencies, server and telemetry schema stay unchanged.

Add coach targets, explanatory hints and recaps. Preserve all nine existing completed IDs at progress version 1, clear discarded Merkle evidence, and constrain the Chain lab to the available width with missions open. Extend Chrome acceptance for all three missions and WebKit acceptance for Merkle proof; update the domain and design documentation.

Verify

• Local: 124 tests across eight affected files, ESLint and production build passed. Three disposable completion-gate mutations failed; restored gates passed.
• Chrome: actual fee/package confirmation, valid-to-invalid Merkle proof, signed-tip tamper/re-mine; both themes at 390, 768, 1366, 1512 and 2560 px. 34 screenshots archived and representative views inspected. Legacy-mission navigation regression reproduced and corrected.
• Exact head 76ce85c5d3a065e065c13b48a77ff7d6b5ed667c: Web checks passed 915 tests / 80 files, Chrome, WebKit, lint/build and deploy check; Server checks also passed. Earlier notice/reset timing failures are preserved with their corrections.
• Merged as ece151756be61a6b9ae14bb19c8ddf545840a119. Its initial publication stopped at the existing Chain lab cancellation check. PR75 corrected clock-resume ordering with the exact zero-attempt/hash assertions preserved; a no-Stop mutation still fails.
• Final master release at 4f79ca6c4b9c708ba54f27f65e9e50641c36d350: complete Web checks, automatic publication, domain/build match and hosted live browser acceptance all succeeded.
• Independent read-only live check at 2026-11-07T15:52:41Z: all twelve mission titles including the three additions visible, no page errors, zero mining actions/API writes. Screenshot and deployed JS/CSS SHA-256 receipts archived in the private package acceptance store.