decred.org/dcrdex@v1.0.5/docs/release-notes/release-notes-0.4.0.md

# DCRDEX v0.4.0

Jan 20, 2022

For a high level introduction to DCRDEX, please read the [initial release's notes](release-notes-0.1.0.md).

## Highlights

This release includes a large number of improvements to wallet support, the UI,
the communications protocol, and software design.

The most notable new features are:

- An integrated light (SPV) BTC wallet
- Support for dcrwallet/Decrediton in SPV mode
- BTC may be used for account account registration
- Introduce an application "seed" for deterministic account and wallet restoration
- UI overhaul and streamlined setup
- Improved market view with candlestick charts and a price feed
- A "remember password" login option to eliminate password nagging
- Translations for Chinese (zh-CN) and Portuguese (pt-BR)
- Extensive under-the-hood improvements

The latest 1.7 release of dcrd and dcrwallet is required for this release of
DCRDEX. At the time of release, this corresponds to the v1.7.0 releases. Bitcoin
Core 0.20 and 0.21 are both supported. Bitcoin Core v22 may be used, but the
wallet type must not be a "descriptor" wallet, which may be the default on
certain platforms and redistributed builds.

Note that we skipped a v0.3 release. The v0.3 development branch is a pre-SPV
checkpoint branch, but it also requires Decred 1.7. Given the timing of the
Decred v1.7 and DCRDEX v0.4 releases now coinciding, we are jumping straight to
the DCRDEX v0.4 SPV-enabled release.

## Important Notices

If upgrading from v0.2, read the [Upgrading](#upgrading) section for important
information.

Always record the "seed" that is generated by the DEX client on initialization
(when you set your password the first time in the browser window). This is a
short string of characters that is used to derive DEX account identities and
initialize any native/built-in wallets you create in the DEX client. **You must
have this seed to recover funds** that you receive in such wallets if your lose
access to your DEX client's data folder.

Although DCRDEX looks and feels like a regular exchange, the "decentralized"
aspect brings an expanded role to the client. Please take the time to read and
understand the following:

- **Never shutdown your external wallets with dexc running**. When shutting
  down, always stop dexc before stopping your wallets.
- If you have to restart dexc with active orders or swaps, you must
  **immediately login again** with your app password when dexc starts up.
- There is an "inaction timeout" when it becomes your client's turn to broadcast
  a transaction, so be sure not to stop dexc or lose connectivity for too long
  or you risk having your active orders and swaps/matches revoked. If you do
  have to restart dexc, just remember to login as soon as you start it up again.
- Only one dexc process should be running for a given user account at any time.
  For example, if you have identical dexc configurations on two computers and
  you run dexc and login on both, neither dexc instance will be adequately
  connected to successfully negotiate swaps.
- Order history is not synchronized between different client installations.

## Upgrading

### Client (dexc)

#### Application Seed

When upgrading from v0.2, an application "seed" is automatically generated upon
login. The seed is used when creating new DEX accounts and native (built-in)
wallets, and may be used to restore these accounts on a new DEX client
installation. You should go to the Settings page to view this new seed, and
**back it up somewhere safe**. This is especially important if you create a
native Bitcoin wallet from within the DEX client since you will need the seed to
recover any funds in the wallet.

If you run the upgrade multiple times, such as from different client
installations or just repeated the upgrade from a v0.2 backup, you will get a
**different seed each time** the upgrade runs and you login.

**Any DEX accounts created prior to upgrading can NOT be later recovered from
this seed.** These "legacy" accounts continue to work in v0.4, but to back them
up or move them to a different installation, it is still necessary to
export/import them from the Settings page or backup the dexc.db file as it was
in v0.2.

**Developer note:** For the upgrade to complete, it is necessary to call `Login`
before using most other `Core` methods. If you receive the error "primary
credentials not retrieved. Is the client initialized?" it is likely that you
need to `Login` first to complete the seed generation and credentials scheme
migration. Typical startup should involve `core.New` followed by: `c.Run` in a
goroutine, wait for `<-c.Ready()`, consult `c.IsInitialized()` before calling
either `c.InitializeClient` or `c.Login`. After login, you should call
`c.ExportSeed` with the application password to retrieve the newly-generated
application seed.

#### Changing the Bitcoin Wallet Type

If you previously had an external Bitcoin Core wallet configured with DEX, you
may switch to a native BTC wallet from the Wallets page. Click the "gears" icon
for the Bitcoin wallet, click "change the wallet type", select "SPV" from the
dropdown box, and click the Submit button. This will start creating a new BTC
wallet. After several seconds it will begin synchronizing in the background, and
a circular arrow icon will be displayed in the Status column of the Wallets
table. Synchronization of the wallet with the Bitcoin network is completed when
the icon disappears. During the process you may see progress by hovering the
mouse over the icon. This normally takes less than 10 minutes, but it may be
longer depending on your network and the peers it established. It is strongly
advised to allow this to complete before attempting to shutdown, change any
wallet settings, or attempt to lock/unlock the wallet. If you decide to change
the wallet type back to an external wallet, you will need to re-enter the RPC
settings that were previously used.

### Server (dcrdex)

There are several changes to the configuration files.

- In markets.json, both lotSize and rateStep no longer belong in the *asset*
  settings, and instead should be configured for each *market*. See
  [4231914](https://github.com/decred/dcrdex/commit/423191441b5bfb569cba6a5de1dcd5a1a8f57855)
  for more information.
- Lot size changes are now supported, but it presently involves restarting the
  dcrdex process after editing markets.json. It is advised to complete swaps and
  purge the market before shutting down. See
  [509205d](https://github.com/decred/dcrdex/commit/509205d4ce4d711b96bb41e596c2c8f100ba7596)
  for more information.
- With registration fees accepted in both BTC and DCR now, the registration fee
  settings should be configured per-asset in markets.json. Previously,
  dcrdex.conf was used to configure these settings for DCR. To accept BTC, a
  "zpub" encoding of your wallet's extended public key for the BIP84 (p2pkh)
  derivation path is required. See
  [4f2ab59](https://github.com/decred/dcrdex/commit/4f2ab59c6fb1fa9e60cb8b953a9a294a2e7c925a)
  and
  [0124247](https://github.com/decred/dcrdex/commit/012424702e9f5ddcd8459d04f25eb6bceb859207)
  for more information.

For examples, consult the sample files: server/cmd/dcrdex/sample-markets.json
and server/cmd/dcrdex/sample-dcrdex.conf

## Client

### Features and Improvements

- The client now uses a seed and deterministic (HD) account key derivation. An
  application seed is generated during client initialization. When a new dex
  account is created, the server's identity is used to deterministically
  generate a client identity for the account. **Users should save a copy of
  their app seed.** When upgrading, a new seed will be generated, which may be
  accessed for backup from the Settings page. When initializing a new dex
  client, there is an option to provide an existing seed. The RPC client
  (dexcctl) also has an `appseed` request endpoint. If an account is suspended,
  a new one will be generated from a different derivation path, and on restore
  from seed, non-suspended accounts will be located.
  ([b66a35f](https://github.com/decred/dcrdex/commit/b66a35f24215456763a16cee9c32875f61f9814b),
  [ac5affe](https://github.com/decred/dcrdex/commit/ac5affe9db320c48534cf4c51e3f7100a6ce4f42),
  [d8e46bb](https://github.com/decred/dcrdex/commit/d8e46bb21e6dcd299343f69257270529aaee6c7e),
  [59868fe](https://github.com/decred/dcrdex/commit/59868fe81173a2d67100ff071d01552cc74fcb1a),
  [7f9d0d5](https://github.com/decred/dcrdex/commit/7f9d0d504b918a58e27576e01b2912b49833a600),
  [d203ebd](https://github.com/decred/dcrdex/commit/d203ebd53127f658e8ae58269907c3c634709e83),
  [242f597](https://github.com/decred/dcrdex/commit/242f597fb1303883eaeb400234a8cffbaa80bf5c),
  [a548723](https://github.com/decred/dcrdex/commit/a5487231f0d1682003617837f279a3b12ef787de),
  [2df3b4b](https://github.com/decred/dcrdex/commit/2df3b4b3f4cdf9e41f87db88936b1cd823c0d36f))
- A new Bitcoin SPV wallet integrated into the DEX client.
  ([c1992d8](https://github.com/decred/dcrdex/commit/c1992d8d1cc11036c4933284a53126b8c452c82d),
  [d202f6d](https://github.com/decred/dcrdex/commit/d202f6d4d0de6884be7dc1bd73a0e865835d6a9b),
  [d808492](https://github.com/decred/dcrdex/commit/d8084925bfe8ded4af88bf4865d8714f8a662b14),
  [2d18cc8](https://github.com/decred/dcrdex/commit/2d18cc80b372d942428eef23824701268a385569),
  [f5835bd](https://github.com/decred/dcrdex/commit/f5835bde802f8d4a7884c3afe1c922daca115455),
  [4249d97](https://github.com/decred/dcrdex/commit/4249d97f02ac0644c03429b9bea0bd401e6e7a73),
  [82833e0](https://github.com/decred/dcrdex/commit/82833e00bdbf4481535c8f57e922312dc06e2840),
  [1890057](https://github.com/decred/dcrdex/commit/1890057fcfee8963f303a5ad354d15f0683f178b),
  [deab1c9](https://github.com/decred/dcrdex/commit/deab1c9deeab70876059d5246c60f023fa6a3e28),
  [3b4f2eb](https://github.com/decred/dcrdex/commit/3b4f2eb6b06f72cba47ecd16cd94bd44ba14f655))
- Decred SPV wallet support (dcrwallet in SPV mode), use compact filters in
  counterparty redemption search, gettxout, gettransaction, etc.
  ([fe1995a](https://github.com/decred/dcrdex/commit/fe1995a42289f29e18bcccd9e537a2ba707a8ad1),
  [1c508cb](https://github.com/decred/dcrdex/commit/1c508cb04d1cc0618843f03abbe4baff2c6a94e9),
  [c5413e8](https://github.com/decred/dcrdex/commit/c5413e8e76cd8f1ca59e2eba524b929cfbf4fa1d),
  [13d12a8](https://github.com/decred/dcrdex/commit/13d12a866dd6886efbca366e665129a67b14a256))
- Add historical market data charts (candle sticks) to the market page.
  ([d11f1ce](https://github.com/decred/dcrdex/commit/d11f1ce9ea1313e17fdc588d0f3d9f0e9e153444))
- Display prices from a new spot price feed from a server market. The current
  rate and 24-hour percent change are displayed in the market list on the left
  of the markets page, and in the browser title.
  ([bb05332](https://github.com/decred/dcrdex/commit/bb05332e7720aa8315e03d35c7fed9cb5023d192),
  [7c0fe85](https://github.com/decred/dcrdex/commit/7c0fe85a565fc39b4492f22e00dbaad1f5ad382c),
  [8ac1498](https://github.com/decred/dcrdex/commit/8ac1498e5573972863985e6b0b7c9f947966087c),
  [10d78e9](https://github.com/decred/dcrdex/commit/10d78e952ba4a05fbb16d1421e637bf00c94ccba),
  [61e9138](https://github.com/decred/dcrdex/commit/61e913882708a2cfc059c1c47b4c48e48462d99c),
  [6231cf4](https://github.com/decred/dcrdex/commit/6231cf403c58a5e39e2a53e7c6457180393cd375))
- Support paying registration fees with multiple assets, now including BTC. The
  `getfee` RPC is replaced with `getdexconfig`.
  ([4f2ab59](https://github.com/decred/dcrdex/commit/4f2ab59c6fb1fa9e60cb8b953a9a294a2e7c925a),
  [0d4075a](https://github.com/decred/dcrdex/commit/0d4075a5451f203eaf9a371b1c4b10bc9a25f287),
  [07c2001](https://github.com/decred/dcrdex/commit/07c20017e565f9135b6e28c9fcb815dfc4445b11))
- Improved registration sequence and form design. Add a table showing all
  markets offered by a server when registering.
  ([ebfcff7](https://github.com/decred/dcrdex/commit/ebfcff744ad90754aba651c0a5d0b998543771a3),
  [027b480](https://github.com/decred/dcrdex/commit/027b480ed39c3b12868547f9590f5fbf19d81359),
  [bbf161e](https://github.com/decred/dcrdex/commit/bbf161eb48ef70f0611ef8f2a9fdfe04690178ea))
- The wallet balance is double checked prior attempting registration.
  ([a5da7349](https://github.com/decred/dcrdex/commit/a5da7349041a005f23aea4a7eb895dd53edc9a47))
- Add the ability to persist password on UI login. This adds a checkbox to the
  login page that gives the user the option to persist their password for the
  session. When selected, all the password fields, other than disable account
  and view seed, will no longer be displayed.
  ([7a0c387](https://github.com/decred/dcrdex/commit/7a0c38735dc030d42ce7af2eb21a25962d4e3ea1))
- Internationalization support for frontend and backend notifications.
  ([7c3d865](https://github.com/decred/dcrdex/commit/7c3d865b21aa5911cd7464c66a93e4070e0bcdd8),
  [6e6cac4](https://github.com/decred/dcrdex/commit/6e6cac4bf16f42ee6ad9e47721bb15263874f22d),
  [0c4d240](https://github.com/decred/dcrdex/commit/0c4d2405d6c2ebe4aa6319cf1245ffd5d5f4bf19),
  [11d4e39](https://github.com/decred/dcrdex/commit/11d4e39fa7d023f99289d0277fc5d9a0fe810166))
- Added a pt-BR translation.
  ([de0f679](https://github.com/decred/dcrdex/commit/de0f6797ad96680a13d67ae4ce785cfe5afac9e2))
- Added a zh-CN translation.
  ([de1d00e](https://github.com/decred/dcrdex/commit/de1d00e78fa66c8bef7ac468c6bc91335b2eb82a),
  [d42e2fa](https://github.com/decred/dcrdex/commit/d42e2fa3af4438602ca091cb58a12519564dc288))
- Lot size and rate step are now parameters of a market, not an asset. For newer
  clients that expect lot size and rate step to be market parameters, this
  detects and supports an older server. Older clients may not support newer
  servers, depending on their configuration.
  ([4231914](https://github.com/decred/dcrdex/commit/423191441b5bfb569cba6a5de1dcd5a1a8f57855),
  [45e3894](https://github.com/decred/dcrdex/commit/45e3894c1e6dc692ecb2b6a25d4388e72128a43f))
- To make order loading in the client faster, split the client order database
  into separate active and archived orders buckets.
  ([e58a139](https://github.com/decred/dcrdex/commit/e58a139d145494f7012e7d980d2f257fb4a1e71e))
- To make match loading in the client faster, split the client match database
  into separate active and archived matches buckets.
  ([283744d](https://github.com/decred/dcrdex/commit/283744d68021b82c43c0a1c6ed2817c3d658a609),
  [e122088](https://github.com/decred/dcrdex/commit/e1220888b9d36f675e9c7972077aa287b97ed7d9),
  [ee34cba](https://github.com/decred/dcrdex/commit/ee34cba600a3a751ef8273b106203ef341a89a7c))
- Log backup swap refund transactions so that the user can salvage funds in the
  case that they lose access to the client but still have the logs. These are
  for BACKUP ONLY as the client will do the refund, and if the user broadcasts
  them unnecessarily, they may cause unrecoverable client issues that could
  necessitate recreating the client DB.
  ([9b012f9](https://github.com/decred/dcrdex/commit/9b012f9242bea5e82431726cd27bbd7d2372294e))
- Bin order tables by rate. Instead of displaying each individual order's
  quantity and rate on a separate row, the total quantity available at each rate
  will be displayed. Epoch orders are binned along with all other orders, and
  the check mark will no longer be displayed.
  ([f7086ab](https://github.com/decred/dcrdex/commit/f7086abac43add3816076cc24ca54875409fe5c6))
- Introduce an "expired" order status for executed orders with 0% filled, and
  for orders that are still booked but currently settling matches to
  "booked/settling".
  ([c8d8d1d](https://github.com/decred/dcrdex/commit/c8d8d1d33d08b02a7cdedbdadfde9cb84a7cc558))
- The order confirmation dialog is now modal, staying open until the submission
  request is processed, displaying any errors on the form.
  ([ff59dbb](https://github.com/decred/dcrdex/commit/ff59dbb8a64ec5d50a348ea918206870657ff387))
- Add an `assetseed` command line tool for the user to derive various
  asset/wallet seeds from their application seed.
  ([4ee4c47](https://github.com/decred/dcrdex/commit/4ee4c478fe7941bff575af1c39617d7945ee091e))
- The Bitcoin Core `rpcconnect` setting is now recognized and used to configure
  the RPC client for such wallets.
  ([2eaa733](https://github.com/decred/dcrdex/commit/2eaa733624d41414d96cb13e377be38af3cf340f))
- When connecting to a Bitcoin Core wallet, check the wallet type to prevent use
  of "descriptor" wallets, which do not support the full set of RPCs required by
  the DEX client. See
  <https://bitcoincore.org/en/releases/0.21.0/#experimental-descriptor-wallets>
  for more information on descriptor wallets.
  ([256cd69](https://github.com/decred/dcrdex/commit/256cd69a73ccaa2af0a31757a5d62e4aab57eddd))
- If a user has active trades, they must be settled by a wallet that can
  complete those trades. Disallow changing to a new wallet that cannot do this.
  ([3fa59cf](https://github.com/decred/dcrdex/commit/3fa59cf4dad60a991346795da25666f9bd215af2),
  [aee00c8](https://github.com/decred/dcrdex/commit/aee00c8abf644b2209a054627090365a0e1858d3),
  [0fc475d](https://github.com/decred/dcrdex/commit/0fc475d99afd93e6f256db7522c701b4e004f8e0))
- Add a "Fees" section to the readme to clarify on-chain transaction fees vs.
  the registration fee.
  ([352809](https://github.com/decred/dcrdex/commit/35280962fd0f2631f3e9c0aa1977a1e3feb71768))
- Automatically check balance before attempting to pay registration fees, and
  show a clear error on the frontend.
  ([cb0e295](https://github.com/decred/dcrdex/commit/cb0e295c185623f38718bbdfd262c904975a2a52))
- Optionally rebroadcast counterparty swap transactions after auditing
  contracts, and log the counterparty redeem script for recovery purposes. Do
  this asynchronously since the outcome is not important.
  ([2e4fe26](https://github.com/decred/dcrdex/commit/2e4fe260b078fa5cb5557b7824bd36aa42ebd8e7),
  [0f7d561](https://github.com/decred/dcrdex/commit/0f7d561a76e57b95174bcdde88a61c51d291f226))
- Wallet connection errors that are encountered on login are show in the
  notification menu.
  ([5149ee2](https://github.com/decred/dcrdex/commit/5149ee2e336047d63eee9a16cddf212fea544d30))

### Fixes

The most notable fixes are:

- Prevent high CPU use with max order size computations.
  ([964fcc0](https://github.com/decred/dcrdex/commit/964fcc0a3cc0e9054f9e171a791ecb84972d5048))
- Keep order form hidden when wallets are not configured (regression fix).
  ([5546ae2](https://github.com/decred/dcrdex/commit/5546ae2964a02932153c074bac38ca930020f634))
- Shutdown the DCR websocket client when a connection attempt fails.
  ([16f357b](https://github.com/decred/dcrdex/commit/16f357b5abaa15a3705fd8ddc1dac538f70bf598))
- With both client and server btc asset backends using dcrd's rpcclient, use the
  correct error type to correctly recognize specific RPC errors from bitcoind.
  ([03f9973](https://github.com/decred/dcrdex/commit/03f9973b77f69f0c8ac0527cc1f7f6e5e15f34ad))
- Fix an unbuffered `os.Signal` channel (CTRL+C was potentially ignored).
  ([e755134](https://github.com/decred/dcrdex/commit/e75513453abae7f1a3e76e82b1c6582888b00ec8))
- Validate the commitment checksum in a match proof notification against the
  checksum from the preimage request to ensure the server did not change the
  epoch after the client provided a preimage for an order.
  ([1c06280](https://github.com/decred/dcrdex/commit/1c06280e1114ad1975a595f70412152ca4538f01))
- Allow only one preimage request per order.
  ([0ab34db](https://github.com/decred/dcrdex/commit/0ab34db44d141aa00300712536306f136eaae832))
- Fix depth chart resizing errors.
  ([fda9187](https://github.com/decred/dcrdex/commit/fda918722c3e2ef96cb9d9cb1d573270c99d7d64),
  [1640b70](https://github.com/decred/dcrdex/commit/1640b7021f70efae83c18795d89ad3700c04cc68))
- Fix max order amount when balance is insufficient for a single lot. Other max
  order fixes.
  ([f118992](https://github.com/decred/dcrdex/commit/f118992badfaa3736fa652594ab6a8df76836e74),
  [015961e](https://github.com/decred/dcrdex/commit/015961e1293079f3c356b48d6378499a0f4cf83e))
- Fix an incorrect asset symbol in the client error log.
  ([92c49d5](https://github.com/decred/dcrdex/commit/92c49d540ec6e1f3ccd9a8abc29a19a9156c088f))
- Correct determination of main chain ancestor on reorg.
  ([cfa95eb](https://github.com/decred/dcrdex/commit/cfa95ebaa34d954f078fef27289c5232ecb0fbae))
- Prevent hang on Decred RPC client shutdown.
  ([0490291](https://github.com/decred/dcrdex/commit/049029115ed80cab484babec9c7a25626c3518b1))
- Restore vertical scroll in orders tables.
  ([499ab0d](https://github.com/decred/dcrdex/commit/499ab0dff19093c993df71bba14e3884b269d0f5))
- Always generate a refund transaction before broadcasting a swap transaction.
  ([bd426fb](https://github.com/decred/dcrdex/commit/bd426fb36118b8561759fa797d2e0981bf8b37a3))
- Do not log negative swap contract expiry durations (when they are just waiting
  on consensus rules).
  ([85bc90f](https://github.com/decred/dcrdex/commit/85bc90fc28ef83b681682c00e7d6809447168b40))
- Fix `match_status` requests failing if "tx data" were required for BTC swap
  transactions.
  ([15f66bc](https://github.com/decred/dcrdex/commit/15f66bcb477ec9221aab927a5ceae306412a98b5))
- Do not try to check for a site directory identified by an empty string.
  ([6743411](https://github.com/decred/dcrdex/commit/6743411c0e6ef58efcfeb7c78b42c67359be7731))
- Resolve data races with `client/core.Core.conns`.
  ([6acc21f](https://github.com/decred/dcrdex/commit/6acc21fff622d3fe8fcf68e8d075cf3d2fceebf1))
- Leave the sequence in Bitcoin and Decred redeem transaction inputs set to the
  max value, since using a lower value was only needed for the refunds when the
  CLTV opcode is used and locktime is relevant.
  ([28473de](https://github.com/decred/dcrdex/commit/28473de0021ff5d2bf53e2a602447b55151ac8de))
- Before broadcasting a swap transaction after startup or reconnect, perform
  match status resolution to ensure the match is not revoked.
  ([983df6b](https://github.com/decred/dcrdex/commit/983df6b04739286950a6ac0293307a46852aaaa2))
- Avoid a (recoverable) panic on RPC wallet connect failure.
  ([8478b6c](https://github.com/decred/dcrdex/commit/8478b6cf85e0d5d685e78657ec4e83e32fed45b0))
- Add a missing error check in `server/db/driver/pg.(*Archiver).LoadEpochStats`.
  ([7957691](https://github.com/decred/dcrdex/commit/795769123971c5dcf8ebfe589e8a4810f737470f))
- Fix handling of P2SH funding UTXOs when 0-conf coins are included.
  ([dda8654](https://github.com/decred/dcrdex/commit/dda86540ad9b585b3165bf0eb06c733576596a9d))
- Show a properly scaled exchange rate in the depth chart's price legend.
  ([94eedbd](https://github.com/decred/dcrdex/commit/94eedbd56241e10c40859ed2206f354688ce8c5e))
- Avoid a potential panic in the BTC native wallet in the event that the best
  block hash cannot be provided by the wallet.
  ([1911080](https://github.com/decred/dcrdex/commit/19110802ab238dd19d3612e2e82e34b8eb4dedd6))
- Promote DEX connections to persistent when the `Register` method finds that
  the account is already paid. Normally this is done in `DiscoverAccount`, but
  should be handled by `Register` as well.
  ([a897f10](https://github.com/decred/dcrdex/commit/a897f10185936292e884e97d922244db81de5856))
- Omit commas from the withdraw amount text field when clicking the max amount.
  ([c987fa8](https://github.com/decred/dcrdex/commit/c987fa86666984e2e926fda6d3e918fbedb840f1))

## Server

- Lot size and rate step are now configured per-market, not per-asset. The
  dcrdex server app now errors if markets.json has lot size or rate step set for
  any asset, and if any market lacks a non-zero lot size or rate step. A
  `'config'` response is generated in different ways depending on if a given
  asset has consistent lot sizes and rate steps across all markets. If
  consistent, it will also set the `LotSize`/`RateStep` in the `msgjson.Asset`.
  If not consistent, the values will be zero/omitted and a warning will be
  logged that old clients will not work with the asset.
  ([4231914](https://github.com/decred/dcrdex/commit/423191441b5bfb569cba6a5de1dcd5a1a8f57855))
- Support lot size changes without manual DB updates.
  ([509205d](https://github.com/decred/dcrdex/commit/509205d4ce4d711b96bb41e596c2c8f100ba7596))
- Accept registration fee payment in multiple assets, including BTC. An operator
  now specifies the accepted fee assets and amounts in market.json settings
  instead of dcrdex.conf. The `'config'` response now includes a `regFees` field
  that communicates these values to clients. Fee address derivation is moved out
  of server/db and into the server/asset packages. To accept BTC, an operator
  must provide a zpub extended public key encoding.
  ([4f2ab59](https://github.com/decred/dcrdex/commit/4f2ab59c6fb1fa9e60cb8b953a9a294a2e7c925a),
  [0124247](https://github.com/decred/dcrdex/commit/012424702e9f5ddcd8459d04f25eb6bceb859207))
- Support clients with HD account key derivation. Return special errors during
  registration when the client's key already exists or is suspended.
  ([b66a35f](https://github.com/decred/dcrdex/commit/b66a35f24215456763a16cee9c32875f61f9814b))
- Allow a client to submit a cancel order while a market is suspended. The
  database entries after a cancel order during a market suspension will be
  identical to one that gets matched while the market is running, except the
  preimage will not be recorded (or requested). Also there will be no entry in
  the epochs table for the epoch in which this order was "matched".
  ([4a3dde1](https://github.com/decred/dcrdex/commit/4a3dde1ef23b8bb40e68130d528d6977486dbf02))
- Route-level request rate limiting.
  ([5e2ab91](https://github.com/decred/dcrdex/commit/5e2ab91533d3fdf9ce774d104fbff844347baa1f),
  [132b16f](https://github.com/decred/dcrdex/commit/132b16f88a619181b1c2f931359816480f8808f2))
- Add a new `price_feed` subscription request route, which is handled by the
  `BookRouter`, and sends `msgjson.Spot` messages to subscribed clients in
  `price_update` notifications.
  ([bb05332](https://github.com/decred/dcrdex/commit/bb05332e7720aa8315e03d35c7fed9cb5023d192))
- Add a `usermatches` command line tool for exporting decoded match data
  directly from the database.
  ([0844058](https://github.com/decred/dcrdex/commit/08440585fbaa7747c142d7073b0ff0305cf72f32))
- Access postgres notices and log them depending on severity.
  ([d6a9c33](https://github.com/decred/dcrdex/commit/d6a9c33d2c68a9f067f7ea8584da176042abefdf))
- Remove pre-schema-versioning DB pseudo-upgrade.
  ([dad4a2e](https://github.com/decred/dcrdex/commit/dad4a2e085417f4f14a50b84276e3133f2aa9f51))
- Increase websocket read limits. Increases the server's authorized read limit
  by a factor of 4 to allow a large number of orders in a single epoch, and with
  more funding coins than normal. Also doubles the unauthorized/default read
  limit, which is still quite small at 8192 bytes.
  ([de775fa](https://github.com/decred/dcrdex/commit/de775fa067e797c6a2f17d7e8eb549aff9752954))
- Remove the `ban` and `unban` administrative functions. Forgiveness is done at
  the level of the match only now, and all administrative interference will go
  away in the future anyway (both fidelity bonds and mesh configuration).
  ([dfbbe9a](https://github.com/decred/dcrdex/commit/dfbbe9a60c5efa577c5cd03f848485927e6c59b3))
- Exclude the maker address from a cancel order match's `msgjson.Match`.
  ([dd31a8](https://github.com/decred/dcrdex/commit/dd31a8d28c524dcff9763b8b333ee200d65af1e2))
- Abandon orphaned epoch orders on startup, which may happen after a hard server
  crash.
  ([bd1599e](https://github.com/decred/dcrdex/commit/bd1599e2545a7cadd5b52fbfd2091b4df2cdeeb8))
- Validate the taker's contract hash during audit, complementing the existing
  client-side check.
  ([10bb7a3](https://github.com/decred/dcrdex/commit/10bb7a3e9f704afc858df1fb4b1cee3ac595284f))
- Fix incorrect encoding of preimage and commitment in an error log.
  ([bc60036](https://github.com/decred/dcrdex/commit/bc60036ba5f2f2a5ed441fd27322340a39911ad7))
- Enable the `rpcclient` package logger, and set up a logging subsystem for the
  `rpcclient` to see connection attempts and other notices from dcrd's
  `rpcclient`.
  ([c1f03e0](https://github.com/decred/dcrdex/commit/c1f03e08b4dc2249fb98abf6ea5a19ceacb2a5d2))
- Fix required order funds check with market buys.
  ([8ca81e2](https://github.com/decred/dcrdex/commit/8ca81e2b4b663222d553a252ee501bc91cda1535))
- Export candles types and make a `dex/candles` package.
  ([26c149a](https://github.com/decred/dcrdex/commit/26c149af45ed42ebf33c8a781925424d087413dd),
  [d11f1ce](https://github.com/decred/dcrdex/commit/d11f1ce9ea1313e17fdc588d0f3d9f0e9e153444))
- Modify `server/dex.feeFetcher` with the context arg, and add a `LastRate` method
  for consumers to use as a fallback if FeeRate fails. Fix an issue where a zero
  rate would be cached on `FeeRate` error.
  ([7ffae7b](https://github.com/decred/dcrdex/commit/7ffae7b215746b646c2ff98084040d594d856493))

## Developer

- Update build requirements to Go 1.16 or 1.17, and Node.js 16 or 17.
  ([75c9b7a](https://github.com/decred/dcrdex/commit/75c9b7a765767f0555e7642fc70e8df3160b65a1),
  [b6cfe2a](https://github.com/decred/dcrdex/commit/b6cfe2aeb9de656531ac0594042575198e9ceaa9),
  [6c95f4f](https://github.com/decred/dcrdex/commit/6c95f4fdbdd6274465fc2d2b2f2595323bd09142),
  [ce823c3](https://github.com/decred/dcrdex/commit/ce823c3315bc8d68b9b2acf81c9265607570b04c))
- (Breaking) Context-enable `asset.Backend.FeeRate`. With a websocket RPC client with
  auto-reconnect where RPCs hang when the RPC server is disconnected, it is
  helpful to allow the caller to cancel requests. Give FeeRate a context arg.
  ([7ffae7b](https://github.com/decred/dcrdex/commit/7ffae7b215746b646c2ff98084040d594d856493))
- (Breaking) Give notifications topic IDs for internationalization support.
  ([c994f03](https://github.com/decred/dcrdex/commit/c994f032fe0e9a36e58a9a984dd924734c659e36))
- Add `(*Core).DiscoverAccount` and an RPC (dexcctl) endpoint to determine if an
  account exists at a DEX server after restoring from seed.
  ([59868fe](https://github.com/decred/dcrdex/commit/59868fe81173a2d67100ff071d01552cc74fcb1a),
  [524b5a1](https://github.com/decred/dcrdex/commit/524b5a1019eb543cb41e49d5a50443f25f2b18f2))
- (Breaking) `(*Core).InitializeClient` has a new `restorationSeed []byte` input
  argument, which may be `nil` to generate a new app seed, or a previous seed
  for to restore a previous identity. The `(*Core).ExportSeed` method is added
  to retrieve the generated seed. Further, the keys, encrypted app seed, and the
  relevant encryption parameters are embodied by the
  `client/db.PrimaryCredentials` struct, and the DB interface has new methods
  for upgrading to, initializing, and updating the `PrimaryCredentials`. When
  upgrading, it is necessary call `Login` for the seed to be generated and the
  new credentials scheme applied, otherwise most methods will fail with "primary
  credentials not retrieved. Is the client initialized?".
  ([b66a35f](https://github.com/decred/dcrdex/commit/b66a35f24215456763a16cee9c32875f61f9814b))
- (Breaking) To support paying registration fees with multiple assets, the
  `core.Exchange` struct has new `RegFees` and `PendingFee` fields, the
  deprecated `ConfsRequired` and `RegConfirms` fields are removed, but the
  deprecated `Fee` field (DCR-specific) remains for compatibility.
  `(*Core).GetFee` is removed and `GetDEXConfig` should be used instead. The
  `core.RegisterForm` struct now has an `Asset *uint32` field to specify which
  asset to pay the fee with. The default if unset is 42 (DCR).
  ([4f2ab59](https://github.com/decred/dcrdex/commit/4f2ab59c6fb1fa9e60cb8b953a9a294a2e7c925a))
- Remove a hard-coded 1e8 constant in the client. This introduces a `UnitInfo`
  type that is defined for each asset and returned in new fields of
  `asset.WalletInfo`, `dex.Asset`, and `msgjson.Asset`. Its
  `(*UnitInfo).ConventionalString` method should be used to convert from atomic
  units to a conventional string representation (e.g. "1.2 DCR"). The
  `client/core.{MiniOrder,RemainderUpdate}` structs are updated with a
  `QtyAtomic uint64` field to complement the existing `Qty float64` fields.
  `MiniOrder` also has a new `MsgRate uint64` field, which communicates rate in
  "message-rate encoding" as [described in the
  spec](https://github.com/decred/dcrdex/blob/master/spec/comm.mediawiki#Rate_Encoding),
  and now modeled in `dex/calc.RateEncodingFactor`, with the new encoding
  helpers `ConventionalRate` and `ConventionalRateAlt`.
  ([08a72d1](https://github.com/decred/dcrdex/commit/08a72d1cd085af6a89dc535ab03184efa6083ad9),
  [ad1c20a](https://github.com/decred/dcrdex/commit/ad1c20a71c10ade6752d422c449fb89b1c5a2338),
  [75fa328](https://github.com/decred/dcrdex/commit/75fa328272d756f13e303c570dba69e07ce0b2c5),
  [207ddcf](https://github.com/decred/dcrdex/commit/207ddcff8d52502b098e93203051f80cc1f862c3))
- Add `SpotPrice *msgjson.Spot` field to `core/Market`.
  ([bb05332](https://github.com/decred/dcrdex/commit/bb05332e7720aa8315e03d35c7fed9cb5023d192))
- (Breaking) To support multiple types of wallets, `client/asset.WalletInfo` has
  a new `AvailableWallets []*WalletDefinition` field to describe available
  wallet types. The `client/asset.Driver` now has `Create` and `Exists` methods
  for "seeded" (native, built-in) wallet types. `(*Core).ReconfigureWallet`
  replaces the `assetID` and `cfg` fields with a `core.WalletForm struct`, which
  now has a `Type string` field. The `core.WalletState` struct now has a new
  `WalletType string` field. A type of `""` (empty string) will be recognized as
  the legacy RPC wallets
  ([d202f6d](https://github.com/decred/dcrdex/commit/d202f6d4d0de6884be7dc1bd73a0e865835d6a9b))
- (Breaking) Move the shutdown prompt function from client/core into client/cmd/dexc. The
  `(*Core).PromptShutdown` method is removed.
  ([1248eb9](https://github.com/decred/dcrdex/commit/1248eb92275cf7dddd98b3cc7c1b97a81be4ab5f))
- (Breaking) Remove the `LotSize` and `RateStep` fields from `dex.Asset`. Add
  the `LotSize` and `RateStep` fields to `msgjson.Market`. `msgjson.Asset` still
  has `LotSize` and `RateStep`, but they are tagged with `omitempty`, and will
  be zero/omitted when market configs require multiple different lot sizes or
  rate steps for an asset. The dcrdex server harness uses a configuration with
  two markets with DCR as the base asset and *different* lot sizes.
  ([4231914](https://github.com/decred/dcrdex/commit/423191441b5bfb569cba6a5de1dcd5a1a8f57855))

- Update Decred dependencies for RPC client syntax changes to `EstimateSmartFee`
  and `GetTxOut`, and decentralized treasury changes to various stake package
  functions.
  ([8976d8d](https://github.com/decred/dcrdex/commit/8976d8d166706ba626cee437d8765fa3ca3794e4))
- Update Decred dependencies for auto-revocation agenda changes.
  ([c2bdeb5](https://github.com/decred/dcrdex/commit/c2bdeb5ab7201460f155cad67f84d9ac99b7c9e5))
- Update Decred `stdscript` dependency and simplify much of the dex/networks/dcr
  package. Several exported functions and types are removed or renamed (breaking
  changes).
  ([920b35a](https://github.com/decred/dcrdex/commit/920b35a59c5def1d1689976a55a108b106a39b8b))
- Replace dcrutil usages with stdaddr.
  ([f37fcbd](https://github.com/decred/dcrdex/commit/f37fcbd2866de14b17b6119177ccb008faf31366))
- Add `build` and `run` scripts to the dcrdex harness for easier testing.
  ([e0a64a7](https://github.com/decred/dcrdex/commit/e0a64a7e66c812daa69b5ef3283c145e0fa33210))
- Use the new `GetTxOutResult.ScriptPubKey.Version` field with dcrd 1.7. Add
  script version checks and use actual version when decoding scripts.
  ([fcd3926](https://github.com/decred/dcrdex/commit/fcd3926fe989d987d18e873ff604f4a754af4ce4))
- Webpack 5 and other build system updates.
  ([1298264](https://github.com/decred/dcrdex/commit/129826436361027a95c0a066b55f7e743e293280),
  [93ac487](https://github.com/decred/dcrdex/commit/93ac4875b847a8c7a63bc889a9ebde966293f10c),
  [fa9b19](https://github.com/decred/dcrdex/commit/fa9b19d1c266d3e1a13e1f54c20d4d42946eed3a))
- Frontend refactoring.
  ([581f852](https://github.com/decred/dcrdex/commit/581f852e249410ee0af030b0a7d277dd517eb085),
  [f7bb867](https://github.com/decred/dcrdex/commit/f7bb867dda5193987280848224796b26220405c2))
- Improve the Decred harness chain reorganization testing function.
  ([c34f5f7](https://github.com/decred/dcrdex/commit/c34f5f7407828e6be12b20df40079b0b49d6b4fd),
  [90b1d92](https://github.com/decred/dcrdex/commit/90b1d9289eb55e74d59840f3a856d44a313559df))
- With internationalization support, CI now checks that the localized_html files
  are up-to-date.
  ([c2ecd94](https://github.com/decred/dcrdex/commit/c2ecd94b4fbf0a9fe8c407573a4df3eb3083b4d8))
- Add a build and packaging script and update it for the localized html
  templates.
  ([245ed7a](https://github.com/decred/dcrdex/commit/245ed7a25eac98d22305eb8ecbb543599923a62c),
  [cf4eb6d](https://github.com/decred/dcrdex/commit/cf4eb6d9afbdb26250fd58f8b30056c105de1ad0))
- Always use IPv4 in comms tests.
  ([7523694](https://github.com/decred/dcrdex/commit/7523694ebf4c7c434e5d982cf95f07bd0aa50bad))
- Update the server administration section of the specification with a link to
  the wiki and an ETH market example.
  ([c7ceb8c](https://github.com/decred/dcrdex/commit/c7ceb8cfb72c6b966514588a9c0fd2324b7c351e))
- Remove all usage of the deprecated io/ioutil standard library package.
  ([b294a00](https://github.com/decred/dcrdex/commit/b294a00be0960821d131357a3ad19adde4e7cbab))
- Set btc test harness node's debug levels per-subsystem.
  ([aa76b62](https://github.com/decred/dcrdex/commit/aa76b62600a37a468b0ad4f4fbb4260fed8722d9))
- Add build meta data to dexcctl.
  ([9c8f52f](https://github.com/decred/dcrdex/commit/9c8f52f22a71e48097ee08332301f11afdd40777),
  [16c81be](https://github.com/decred/dcrdex/commit/16c81be31c9abc3cb7fb05a5065a92d925b16596))

## Ethereum (not enabled in 0.4)

- Add internal ethereum client
  ([16da72f](https://github.com/decred/dcrdex/commit/16da72f5e3af049db315400c68b87d7957c15bfa),
  [f4194e0](https://github.com/decred/dcrdex/commit/f4194e0b064133e4dce8bc4bea1eac148d6e9793),
  [d0e5f31](https://github.com/decred/dcrdex/commit/d0e5f31015815f898b35cda6fff30e495753e5f5),
  [3ea9141](https://github.com/decred/dcrdex/commit/3ea91418306c658d15dfbd369a737ec5eaf01e9b))
- Add the ETH swap contract solidity and compiled ABI.
  ([a7046c6](https://github.com/decred/dcrdex/commit/a7046c670b4f824b7b5e237c9efcecbd8fc5e604),
  [a6eca9e](https://github.com/decred/dcrdex/commit/a6eca9e972507e8e797a0d4b844e4bafd5cdc9ee),
  [39fbfce](https://github.com/decred/dcrdex/commit/39fbfce546a70b98d1285a237af717b8478cc878),
  [beaf951](https://github.com/decred/dcrdex/commit/beaf951f96b7fff8162dc9acc5cf9798519eac41),
  [202465e](https://github.com/decred/dcrdex/commit/202465e1ee4e717f4a6ba1563c878a2a282b01a1),
  [ead7bdd](https://github.com/decred/dcrdex/commit/ead7bdd89a037650966b0e9cca7e6c5a00c4326a))
- Implement the required `client/asset.Wallet` methods.
  ([783bf2c](https://github.com/decred/dcrdex/commit/783bf2c41ae5f22a4af8c82e9d15838e6d55ec8e),
  [72212a8](https://github.com/decred/dcrdex/commit/72212a8bfa41ec3a22a6d9bcfa9e6471584dbae5),
  [d9611e5](https://github.com/decred/dcrdex/commit/d9611e5678da6cbc1726a72e696d0d193e02443e),
  [8bd3a34](https://github.com/decred/dcrdex/commit/8bd3a34054f6961493cae64e8958a7e7d90e06d9),
  [5f1928b](https://github.com/decred/dcrdex/commit/5f1928bc9bf3408afe40f60b4ca043172246defe),
  [cef9c5c](https://github.com/decred/dcrdex/commit/cef9c5c2b22a44ee434bb5dd7b00b54ad375043d))
- Implement the required `server/asset.Backend` methods.
  ([fed96f5](https://github.com/decred/dcrdex/commit/fed96f585cdd7d423589d3fb1ebc78aefa3c3f82),
  [9e1e0cb](https://github.com/decred/dcrdex/commit/9e1e0cb8787ca6ec48463ac006084c3a1e0ee461),
  [4aa78e1](https://github.com/decred/dcrdex/commit/4aa78e14c4d0b35830b1719d5febf19086e714fe),
  [2dac253](https://github.com/decred/dcrdex/commit/2dac2536a94431442ac23769a2142e46b8bd78c6),
  [05367f1](https://github.com/decred/dcrdex/commit/05367f10fbc7c69ba303821d3f75e045f705689f))
- Add a shell script that generates go code containing the runtime bytecode of
  the swap contract.
  ([7f9793e](https://github.com/decred/dcrdex/commit/7f9793e3932b1ebcf1fa0e0fc29e5dec1333fb2c),
  [9df4f78](https://github.com/decred/dcrdex/commit/9df4f78ad99c479f1033f6a878c9482b6aea71bd))
- Functions to decode transaction data.
  ([ec3b7fd](https://github.com/decred/dcrdex/commit/ec3b7fdeada0e7609e176fd93e06118f46c8c8fe))
- Derive ETH wallet account keys from the dex client application seed.
  ([7c2058f](https://github.com/decred/dcrdex/commit/7c2058ff24d89979ddac013054deb74471900764))
- Use snap mode for server nodes in harness.
  ([68d1e64](https://github.com/decred/dcrdex/commit/68d1e64a73c10a98d7a00035985b8b7828cb361c))

## Build requirements

- Go 1.16 or 1.17
- Node 16 is the minimum supported version for building the site assets.
- dcrd and dcrwallet must *still* be built from their `release-v1.7` branches.
- The minimum required dcrwallet RPC server version is 8.8.0, which corresponds
  to the v1.7.0 release of dcrwallet, but the latest `release-v1.7.x` tag should
  be used.

## Code Summary

186 commits, 330 files changed, 50,332 insertions(+), 23,221 deletions(-)

<https://github.com/decred/dcrdex/compare/ba59397...release-v0.4>

12 contributors

- Amir Massarwa (@amassarwi)
- Brian Stafford (@buck54321)
- David Hill (@dajohi)
- Dominic Ting
- @iurii
- Joe Gruffins (@JoeGruffins)
- Jonathan Chappelow (@chappjc)
- @martonp
- Peter Banik (@peterzen)
- Victor Oliveira (@vctt94)
- Wisdom Arerosuoghene (@itswisdomagain)
- @xaur