TSUNAGI
An independent Cardano node implementation, written in Zig
Not a fork of cardano-node and not a wrapper around it. TSUNAGI produces canonical blocks on the Cardano Preview chain, adopted by unmodified cardano-node peers under normal consensus rules and verifiable by anyone. Sovereign Mainnet qualification is underway. Built without grants. Built without treasury funding. Built in public.
Preview release · follower mode · v2026.10.05 · Linux x86-64 · portable baseline · checksum & install
Proven today. In development.
It happened on a live network or in a recorded rehearsal, and the evidence is public.
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Canonical block production on Cardano Preview
Blocks forged, signed and served by TSUNAGI, adopted into the canonical Preview chain by unmodified cardano-node peers. … canonical blocks so far · every block, and every orphan.
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Public Preview follower release, qualified
v2026.10.05, portable Linux x86-64: clean empty-home startup, ChainSync, BlockFetch, transaction decoding and application, persistence and cold restart — 1,506 / 1,506 tests green. It follows the chain; it is not the producer build behind the blocks above. Download
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Guardian-supervised crash recovery
In a controlled rehearsal on the live Preview producer (June 2026), a hard kill was detected, evidence captured, and the node restarted in 3.8 s with no human action. Guardian
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Read-only Mainnet following
July 2026: a read-only TSUNAGI follower completed a 7-day Mainnet observation window, and a 24-hour soak against the Haskell reference matched 2,682 / 2,682 block heights with zero hash mismatches. Mainnet
Direction and work in progress. Nothing in this column is claimed as complete.
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Sovereign Mainnet qualification underway
Sovereign means TSUNAGI's own ledger decides whether each Mainnet block is valid; external references serve only as cross-checks. The final Node V1 completion campaign is running now. Node V1 has not yet been declared ready.
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Mainnet block production not enabled
TSUNAGI produces no Mainnet blocks. Enabling production is gated on completed qualification and a separate operator decision.
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Autonomous operation in development
Designed for operation with minimal operator intervention. Building on Guardian's crash recovery: safe self-recovery when the process stays alive but stalls, automated update qualification, and rollback.
Verify independently:
curl "https://preview.koios.rest/api/v1/pool_blocks?_pool_bech32=pool1nu2…fw5ts"
— the chain is the source of truth, not this website.
An independent implementation, not a fork
TSUNAGI is an independent implementation of the Cardano node, written in
Zig. Its block producer is a from-scratch implementation of the
Cardano block-producer role: it evaluates VRF leadership for every slot, forges
and signs blocks (KES/opcert), publishes them atomically, and serves them to peers
over the standard node-to-node mini-protocols — ChainSync and BlockFetch — to an
unmodified cardano-node, which accepts them into the canonical chain.
It is not a fork of the Haskell node, not a wrapper, and not a simulation. Every canonical block listed on this site was forged by this code and adopted by the Cardano Preview network under normal consensus rules, competing against every other pool's blocks.
On Mainnet, TSUNAGI does not produce blocks. It is in sovereign Mainnet qualification, progressing from proven Preview operation toward fully qualified Mainnet operation. See /mainnet/.
Built without permission
A real implementation
Not a fork, not a wrapper — an independent implementation of the Cardano block-producer role.
Written in Zig
One native binary — no virtual machine, no garbage collector. Low-level and auditable.
Zero grant funding
No Catalyst, no foundation grants, no VC. The work funded itself.
Zero treasury draw
Not a single ada of treasury money. Independence is the point.
Every failure becomes a test
Each closed incident is pinned by a regression test. A frontier cannot silently reopen.
Every incident recorded
Fourteen incidents documented — thirteen verified-closed, one recovered pending root cause — in the Kintsugi record.
Every block recorded
Every canonical block is listed and verifiable against the chain — including the orphans.
Truth-first by design
Nothing here is a marketing counter. If a value can't be fetched, the site says unavailable.
Five guardians, one node
TSUNAGI's architecture is organized around five named subsystems — observe, protect, recover, reconnect, learn. The full explanation, with diagrams, is on the Architecture page.
Designed for autonomous operation. A Guardian supervisor watches the node and restarts it after a crash, capturing evidence first. TSUNAGI is being developed toward safe self-recovery, automated update qualification and rollback with minimal operator intervention — see Guardian.
Observe
Self-observation: acceptance tracking, verdicts, external cross-checks against the chain.
Protect
Forge gates that refuse any block the node cannot prove valid to itself first.
Recover
Watchdogs, quarantine, rollback chains — failure never cascades.
Reconnect
Parked peers, contiguous push walks — the network path that wins the propagation race.
Learn
The failure-memory system: every incident becomes a regression test and a documented lesson.