Fiber Dev Log 2026-07-09

[chenyukang]

Updates

Fiber stayed in v0.9 release-hardening mode from June 25 through July 8, 2026.

Development prioritized reliability and release readiness over new features. The strongest themes include WASM and gossip-sync performance, CCH reconciliation, payment and TLC safety, watchtower failure handling, and packaging/test stability.

Integration work also expanded around native/mobile embedding: the Fiber FFI (the foreign function interface layer for Fiber nodes) path now has clearer guidance for host-language wrappers, lifecycle handling, callbacks, memory ownership, and platform integration.

Features

v0.9 Release Candidates

• Fiber published three release candidates during this cycle, including CCH fixes, gossip-sync improvements, WASM performance work, and final node-announcement cleanup:
  • v0.9.0-rc5 release
  • v0.9.0-rc6 release
  • v0.9.0-rc7 release
• Final v0.9.0 remains pending: v0.9 milestone

Storage Recovery

• Backup and restore supports were added for storage backends, providing a critical recovery capability for node operators: feat: add backup and restore for storage backends

Fiber FFI Integration

• Fiber FFI Architecture & User Guide: We published new documentation on Fiber FFI, the foreign function interface (FFI) for Fiber nodes. Fiber FFI allows non-Rust developers embed Fiber node into their Android, iOS, and desktop platforms, through a dynamic library, without rewriting the core logic.

• Capabilities: Allows the host app to directly manage node lifecycles, peer connections, channels, and payments.

• Guidelines: Establishes clear rules for cross-language communication and safe memory handling.

• Status: Experimental. Recommended for prototyping and building language bindings, but needs further testing before production use.

Improvements & Fixes

WASM, Gossip Sync, and Graph Reliability

• Browser/WASM and graph-sync paths were tightened through packed CKB RPC usage, concurrent channel-announcement verification, CKB RPC timeouts, batched WASM store commits, active-sync fixes, and SharedArrayBuffer IPC synchronization:
  • perf: use packed CKB RPCs for CA verification
  • perf: concurrent CA verification in prune_messages_to_be_saved
  • fix: add CKB RPC timeout for WASM
  • perf: batch WASM store commits into single IPC call
  • fix: resolve graph sync deadlock caused by message timestamp ordering
  • Fix WASM DB worker IPC synchronization over SharedArrayBuffer

CCH and Payment Lifecycle

• CCH and payment lifecycle handling improved around pending-expiry reconciliation, attempt status tracking, shared payment-hash preimage cleanup, LND compatibility, and forwarding TLC expiry protection:
  • Fix CCH pending expiry reconciliation
  • Track Fiber attempt status changes for CCH orders
  • Fix preimage cleanup for TLCs that share the same payment hash
  • Accept zero LND preimages on success
  • Protect forwarding TLCs from premature expiry

Protocol and Operational Hardening

• Security-review follow-ups continued through public hardening PRs for funding acknowledgement, derived TLC public keys, short routes, actor failure handling, watchtower pagination errors, and sessions without remote pubkeys:
  • Require funding signature acknowledgement
  • Reject invalid derived TLC pubkeys
  • Avoid panic on short payment route
  • Avoid supervisor panic on actor failure
  • Abort watchtower scan on RPC pagination error
  • Avoid panic on session without remote pubkey

In Pipeline

v0.9 Finalization

• Final v0.9.0 remains pending. The latest confirmed pre-release is v0.9.0-rc7, and the v0.9 milestone remains open with one remaining item as of July 8, 2026.

Force-Close TLC Settlement

• On-chain TLC settlement for force-closed channels
  • feat: handle on-chain TLC settlement for force-closed channels

CCH and Payment Safety Follow-Ups

• Under review: CCH cleanup, TLC expiry handling, and retry behavior.
• Ongoing: Broader CCH multi-asset swap implementation.
  • Fix CCH incoming invoice cleanup on expiry
  • Fix payment TLC expiry limit random delta
  • fix: retry only failed payment attempts on channel ready
  • feat: CCH multi-asset swap

Gossip, Channel State, and Sync Hardening

• Draft / Under Review: Gossip peer cleanup, invalid-message peer banning, active-sync retry limits, and the channel-state split:
  • Ban peers after repeated invalid channel messages
  • Abort active sync after pending retry limit
  • Cleanup gossip peer outbound state on disconnect
  • Draft: Split channel state into immutable/mutable data

Packaging and Test Infrastructure

• Under Review: Release packaging and test-helper work:
  • Fix Windows release CRT dependency
  • test: add start_for_test method for RootActor

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Thanks @Zhangcy0x3 for great contribution for the feature of backup and restore 🥳