Channels begin with funding and end with a close. How you close determines fees, delay, and risk.
Why this matters
Force closes are expensive and slow. Lost channel state without backups can lose funds. Lifecycle literacy is operational safety.
Close types
- Cooperative close: both agree, efficient on-chain settlement
- Force close: broadcast latest commitment; timelocks may delay funds
- Penalty: response to revoked state broadcast
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Common mistakes
- Force closing to “speed up” when fees are high
- Running nodes without disk redundancy
- Ignoring unresolved HTLCs during close
Worked mental model
Re-read the diagrams in this lesson once out loud in plain language. If you cannot explain the flow to a friend without jargon, pause and revisit Mastering Bitcoin / Mastering Lightning chapters linked in Resources. Chapter references are intentional, not decorative.
Hands-on habit
Every protocol idea should be paired with one local experiment:
- Reproduce the happy path on regtest (or Polar for Lightning)
- Break it on purpose (wrong fee, expired invoice, offline peer)
- Write down what error you saw and which layer produced it (wallet, node, mempool, peer)
That habit turns reading into builder instinct.
Glossary check
Pick three terms from this lesson and define them in one sentence each without opening notes. Weak definitions mean the lesson is not finished yet.
Resource order
Use Resources in order: narrative book chapter first, then BIP/BOLT for precision, then implementation docs for commands. Jumping straight to RPC flags without the mental model creates brittle knowledge.
Next steps
Dual funding and splicing change capacity without a full teardown.