Source: [pcoc `services/bari/README.md` at aaa8946](https://github.com/groundinglab/pcoc/blob/e50939608e3c3ae68e2e7b330e59d345652c171f/services/bari/README.md), with Hashcash and plant-tag detail from [OPERATING.md](https://github.com/groundinglab/pcoc/blob/e50939608e3c3ae68e2e7b330e59d345652c171f/services/bari/OPERATING.md) and [plant-attribution.md](https://github.com/groundinglab/pcoc/blob/e50939608e3c3ae68e2e7b330e59d345652c171f/spec/plant-attribution.md).

# bari

One binary, `bari`. Crate `pcoc-bari`, library `pcoc_bari`, version 0.6.8, tag `bari-v0.6.8`.

It accepts 32-byte waypoints and later serves a Merkle path. It writes the index cache. It does not serve `GET /index`. The index HTTP reader is [services/index](https://github.com/groundinglab/pcoc/blob/e50939608e3c3ae68e2e7b330e59d345652c171f/services/index/).

Bari timestamps waypoints by sealing each tip's pool into one Bitcoin transaction. The plant fee buys position, not work. Bitcoin's proof-of-work does not secure a PCOC and does not pay for the hike.

## Routes

| Surface | Role |
|---|---|
| `POST /waypoint` | Append a 32-byte waypoint to the live tip's pool (Hashcash required) |
| `GET /path/{leaf}` | Serve the Merkle path for a confirmed leaf |
| `GET /ops` | Operator page |

## Hashcash

Required on `POST /waypoint` only. Header: `X-Bari-Hashcash-Nonce: <u64 decimal>`.

| Item | Value |
|---|---|
| Message | `SHA256(challenge ‖ waypoint ‖ nonce_le_u64)` |
| Challenge | `SHA256(b"bari-hc-v1" ‖ tip_hash)` from the live tip |
| Difficulty | 21 leading zero bits (fixed; shared with produce) |

A `204` means the waypoint was appended or was already held. It is not a promise that a path will be served.

## Plant tag

Each plant is one Bitcoin transaction. The commitment is a **39-byte** output script:

`OP_RETURN` ‖ push-37 ‖ `BARI` ‖ `0x02` ‖ the 32-byte Merkle root

That tag alone marks a plant for the initial release. Operator key attribution on funding inputs is a later, optional step ([plant-attribution.md](https://github.com/groundinglab/pcoc/blob/e50939608e3c3ae68e2e7b330e59d345652c171f/spec/plant-attribution.md), proposed, not normative).

## Cycle (short)

1. Clients `POST /waypoint` into the pool for the live tip.
2. While the mempool next-block minimum is below 1.1 sat/vB, Bari seals the pool into one tree and broadcasts a plant.
3. The anchor window is 5 blocks from the broadcast height. Inside that window, `GET /path/{leaf}` returns inclusion height, txid, and Merkle path.
4. A confirmed path stays servable after the window. There is no fee bump and no second broadcast of the same tree.

## Tip modes

| Mode | What it is |
|---|---|
| Live | `BARI_TIP_SOURCE=bitcoin-gossip`, plus a Bitcoin Core plant |
| Test | `BARI_TIP_SOURCE=synth`, plus a simulated commit |
| Unset | `BARI_TIP_SOURCE` remains the RPC poll and is not the live tip |

## Pins

`hike` and `hike-net` are pinned at **`ref-rust-v2.0.5`**.

## More

- [OPERATING.md](https://github.com/groundinglab/pcoc/blob/e50939608e3c3ae68e2e7b330e59d345652c171f/services/bari/OPERATING.md) — full HTTP table, operator page, fixture command
- [pool-handoff/REQUIREMENTS.md](https://github.com/groundinglab/pcoc/blob/e50939608e3c3ae68e2e7b330e59d345652c171f/services/bari/pool-handoff/REQUIREMENTS.md)
- [deploy/bari.service](https://github.com/groundinglab/pcoc/blob/e50939608e3c3ae68e2e7b330e59d345652c171f/services/bari/deploy/bari.service)
- [deploy/env.example](https://github.com/groundinglab/pcoc/blob/e50939608e3c3ae68e2e7b330e59d345652c171f/services/bari/deploy/env.example)