Using dp_exchange_coinbase

EXPERIMENTAL. Not run in production. Pin three-part. Maturity is per endpoint — read capabilities/0, not this banner.

Everything general is in dp_exchange_core's usage rules. This file is only what is specific to Coinbase.

Start it, and it brings its own rate limiter

children = [{DpExchange.Coinbase, credentials: my_credentials()}]

The venue supervises a limiter configured from the ceilings it declares. That is not a convenience: Core.HttpClient fails closed when no limiter is reachable, so a venue package that expected someone else to start one answers {:error, "Rate limiter unavailable"} to everything.

Which of the two declared ceilings the limiter is configured from follows whether you passed credentials: above — see "Credentials choose the endpoint" below. Pass none and the limiter runs at public_ceiling; pass a non-empty credential map and it runs at authenticated_ceiling instead, matching whichever request path Rest actually takes for this instance.

Running two — two credentials, two scopes — needs distinct names:

[{DpExchange.Coinbase, name: :cb_a, feed: :cb_a_feed, limiter: :cb_a_limiter},
 {DpExchange.Coinbase, name: :cb_b, feed: :cb_b_feed, limiter: :cb_b_limiter}]

A shard's socket crash costs one shard, never your whole subscription

Each level2/ticker shard runs on its own socket, and that socket is a linked child of Feed — not a supervised sibling you can restart independently. As of this version Feed traps exits, so a shard's socket dying abnormally no longer takes Feed down with it: only that one shard's symbols drop out of coverage/1 and coverage_by_kind/1 (only the data_kind() its channel carries — a level2 crash never touches a symbol's ticker coverage), you get a :link_down Core.Notice naming which shard and why, and this package reopens that shard on its own, immediately, without you calling subscribe/2 again.

What still costs you your whole subscription: Feed itself crashing — a bug outside the socket-crash path, or anything that kills the Feed pid directly. DpExchange.Coinbase.Supervisor restarts Feed under :one_for_one, but from the static opts your supervision tree started it with; every subscribe/2, update_symbols/2 and subscribe_notices/1 call you made afterward is gone; coverage/1 reads empty until you call subscribe/2 again. Nothing inside this package can replay those calls — it never held onto the functions or the process that made them. If your consumer needs to survive a Feed restart unattended, monitor the Feed pid (or the DpExchange.Coinbase pid it sits under) yourself and re-issue subscribe/2 on :DOWN.

Your api_key/api_secret will not appear in the crash log. Feed and Socket both hold your credential for as long as they run, and a crash of either logs that process's state via OTP's default crash report — which is where you would see it, because a crash report prints unredacted Logger metadata otherwise. Both processes wrap the pair in a struct before it ever reaches state, so the crash line reads credentials: #DpExchange.Coinbase.Credentials<...> rather than the key pair itself. This is not a claim about your own code: if you read state.credentials yourself via :sys.get_state/1 or similar, you get the same struct — call Map.from_struct/1 on it to get the plain map back.

Credentials choose the endpoint; they do not gate it — except one call

Coinbase serves almost all market data publicly and authenticated. Pass credentials and this package uses the authenticated path, which has the higher ceiling. Pass none and it uses the public one. The return is identical either way.

Declared as credential_benefit: :higher_ceiling — a boolean could only have said "required" or "not", and neither is true for the package as a whole.

get_top_of_book/2 is the one exception. The venue publishes no public form of /best_bid_ask — confirmed live, 401 authenticated and 404 at the /market/... path every other reader here has. Call it without credentials and it returns {:error, {:missing_credentials, :coinbase}} before sending anything, rather than surfacing the venue's 401 as an opaque error. Not {:refused, _}: the credential never left this process, so nothing at Coinbase ever saw a request to decline.

Nine candle widths, and 12h is not one of them

1m 5m 15m 30m 1h 2h 4h 6h 1d. The shared vocabulary models 12h; Coinbase does not serve it, and asking for it is an error rather than the nearest width.

That is not caution. A caller once received one-hour bars labelled four-hour, which the backfill then stored tagged 4h — every value real, every label wrong, and nothing failed. Coinbase itself refuses an unknown width outright, measured 2026-08-28:

parsing field "granularity": "THREE_HOUR" is not a valid value

350 candles is a hard boundary, not a page size

Measured: 350 minutes of one-minute candles returns 349. 351 returns zero and an error — not the first 350.

This package refuses an over-wide range up front:

{:error, {:range_too_wide, requested: 400, max: 350}}

Widening your window to "get more per call" gets you nothing, and nothing reads as no data for this period. Page it yourself.

Coinbase publishes no rate-limit headers

Measured: no x-ratelimit-*, no retry-after. The ceiling is not discoverable from a response, so capabilities/0 declares it and measured_against says where the numbers came from — the granularities and the 350 boundary were probed against the live venue; the ceilings were not and are inherited from a prior implementation.

If you have better numbers, that field is where to correct them.

Refusal versus error

• {:refused, :not_listed} — Coinbase does not carry this symbol. Permanent. Stop asking.
• {:refused, {:venue_error, status, message}} — a 400, 401 or 403: the venue received the request and declined it, in its own words. Permanent for the request as sent — a caller whose key was rotated signs again with the new one, which is a different request rather than a retry of this one.
• {:error, {:unsupported_timeframe, tf}} — a width it does not serve. Your mistake, not a transient one.
• {:error, {:missing_credentials, :coinbase}} — this call needs a credential and was not given one, detected here before anything was sent. Never {:refused, _}: the venue received no request to decline.
• {:error, reason} — everything else. Retry as your policy allows.

The 4xx statuses are read from the status, not from the message text

Worth stating because the previous behaviour was wrong in both directions and a consumer may have built around it. This package used to recover the HTTP status by searching the flattened error string for "404", which meant:

• a 4xx whose body happened to contain "404" — an order id, a price, a vendor code — came back {:refused, :not_listed}: permanent, never retried, for something that may well have been transient; and
• a 400, 401 or 403 contains no "404" anywhere, so a bad request or a rejected credential fell through to a bare {:error, message} and read as possibly-transient — a rotated key retried instead of refused.

Both are fixed; the status is now matched exactly, as the other four venue packages in this family already did. If you were matching {:error, message} for authentication failures, they now arrive as {:refused, {:venue_error, 401, _}}.

Signing failures stop here, rather than being sent unsigned

A credential that cannot produce a signature — a malformed api_secret, or a map missing :api_key / :api_secret — refuses locally, before anything is sent: {:error, :invalid_base64}, {:error, {:unsupported_key_size, n}}, or {:error, {:missing_credentials, :coinbase}}.

This package used to drop the Authorization header and send the request anyway. On a public market-data GET that is harmless — Coinbase serves those anonymously. On a write there is no public path, so place_order/3 and every other POST went to the venue unauthenticated and came back an opaque 401 that reads like a problem with your account rather than with the key you passed. An unsigned token is worse than none.

Streaming

subscribe/2 opens and manages a connection internally. You never see it, and coverage/1 reports what is observed arriving — a symbol you subscribed that has delivered nothing is simply absent.

Public channels carry no token. Attaching one is actively harmful: Coinbase answers a bogus token with an authentication failure, which is how a book channel once produced nothing while the public ticker worked fine — a venue half-delivering looks like a quiet market rather than a broken credential.

:order_book needs a credential; :quotes does not

capabilities/0 now says so: streamable is [:quotes, :order_book] and authenticated_streamable is [:order_book]. Without credentials this package subscribes ticker alone, so you get quotes and no book.

That second field was left empty until now, which reads as "nothing here needs a credential". A host deciding whether it had to obtain one before it could stream book data was told no, and would have discovered otherwise from a book stream that simply never arrived — ask capabilities/0 rather than waiting to find out from coverage/1.

Frames are tagged with the symbol you subscribed, not whatever the venue renamed it to

Coinbase silently rewrites some product ids on delivery. Subscribing ticker to an aliased -USDC pair (e.g. XLM-USDC) delivers every frame tagged with its -USD counterpart instead — and the venue's own subscription acknowledgement echoes the rewritten name back, not the one you sent. Measured live 2026-09-05 against wss://advanced-trade-ws.coinbase.com; confirmed against the venue's own /market/products catalogue, where 112 of the first 114 USDC products carried a non-empty alias naming their -USD counterpart.

This package undoes that before a frame reaches you: every Types.Quote, Types.OrderBook and Types.OrderBookDelta you receive is tagged with the symbol you subscribed, resolved against the venue's own declared alias relationship — never the venue's rewritten name. Subscribe to both names for a market the venue aliases and you get both, from the one frame the venue actually delivers. coverage/1 follows the same rule: it reports under what you subscribed, never under what the venue renamed it to.

If the venue's product catalogue can't be fetched, attribution degrades rather than guesses: frames deliver under whichever id the venue actually sent, and subscribe_notices/1 receives one :data_quality notice saying attribution is degraded and why. There is no -USDC/-USD string-munging fallback — it would be wrong for any pair the venue does not actually alias.

level2 delivers deltas, not a maintained book — BREAKING as of 0.2.0

Before 0.2.0, subscribing level2 delivered a full Types.OrderBook on every frame, including a single-row update — this package held the book itself and rebuilt it on your behalf. That was market state duplicated inside a socket process for no reason a consumer could see, and it was expensive enough to threaten this package's own job: at the book size DpCryptoManagement measured live for BTC-USD (~22,800 bid / ~21,100 ask levels), rebuilding it cost 65–110 ms on the same single-threaded process responsible for sending your subscribe frames, capping throughput and starving ticker.

As of 0.2.0, this package holds no book, and you receive exactly what the venue sent:

• A snapshot frame (once per subscribe, or resubscribe) delivers a Types.OrderBook — the venue's whole book at that moment, bids and asks sorted best-price-first, as the contract always promised.
• An update frame delivers a Types.OrderBookDelta — the venue's own changed rows, in the venue's own order, both sides interleaved exactly as the frame carried them. levels is a flat [{side, price, quantity}] list rather than split into bid_levels/ask_levels, because one delta frame can change both sides at once and a per-side split would either drop the venue's ordering or invent one it never sent.
• A quantity of zero means that price level ceased to exist — not a price of zero. This package carries that through unresolved; it does not drop the row, and it does not fold it into anything held here. If you want a maintained book, you build and hold it yourself from the stream of deltas — that is now genuinely your job, not a trap this package used to spring on whoever forgot to check.

Reconnect reconciliation is now your problem, and here is what to reconcile with. A dropped-and-restored connection does not promise the deltas after it are contiguous with the deltas before it. subscribe_notices/1's :link_down and :link_up bracket where a gap may have opened; neither that notice nor anything else reconstructs a missing delta. The correct response to :link_up is to re-pull get_order_book/2 (unaffected by any of this) or accept the venue's own fresh snapshot on resubscribe — not to keep applying deltas across the gap and hope they still line up. Coinbase's level2 channel does not publish a book sequence number, so :sequence on both types is always nil here; where a venue does publish one, it is the other half of this reconciliation.

resubscribe_interval_ms — re-issuing subscriptions is unconditional, and the cadence is diagnostic, not a knob to tune coverage with

A WebSockex reconnect resubscribes nothing on its own, so a dropped-and-restored socket can come back up connected and silently subscribed to nothing. This package re-issues every shard's current subscriptions on a timer to cover that, unconditionally.

children = [{DpExchange.Coinbase, credentials: my_credentials(), resubscribe_interval_ms: 30_000}]

Default is 60,000 ms, and it is a diagnostic knob, not a way to make coverage catch up faster. A value shorter than one full re-issue cycle across your current shard count is not honoured: this package derives the floor from the shard count that actually exists — (shards - 1) * 5_000ms + 5_000ms — and uses that instead, logging the substitution, rather than wedging the feed with overlapping re-issue cycles queued behind each other. That is a real, measured incident (DpCryptoManagement's issue #22): it happened both from an explicit resubscribe_interval_ms: 5_000 and from the 60s default past thirteen shards. There is no way to make this package re-issue faster than that floor — only a log line explaining why it didn't.

Shard count now counts level2 and ticker separately, and level2 needs more of them than ticker does — see the next section. Thirteen shards is reachable from level2 alone once your universe passes 360 symbols; it no longer takes 1,101 symbols the way it did when both channels shared one 100-per-socket grouping.

A shard whose socket never opened at all is retried on this same cadence, and it says so. A transient connect failure on a shard beyond the first (a brief DNS blip, a refused connection) used to have no automatic recovery — nothing re-asked the venue for it until you called subscribe/3 or update_symbols/2 again yourself, which may never happen if your scope is stable after boot. It is now retried on every unconditional tick alongside already-open shards' own resubscribes, and subscribe_notices/1 receives a :coverage_change notice the moment the attempt fails — the same kind a channel that never subscribed already produces — so you learn about it rather than inferring it from a symbol that quietly never joined coverage/1.

level2 shards far more finely than ticker, and ramps in more slowly because of it

level2 has a per-session product ceiling ticker does not; Coinbase names the failure ("too many L2 streams requested in a single session") but documents no number, and this package cannot bisect a live authenticated session to find one itself — see this file's own "Do not point tests at the live venue" rule, which applies to this package's own development as much as to yours.

The ceiling is now measured, not merely bounded from below. A consumer holding real credentials — this repo structurally never does — bisected it live on 2026-09-06: n = 6/12/25/30 accepted, n = 31/35/50/100 refused, the boundary confirmed by interleaving two runs back to back and by a contamination check ruling out the refusals being an artefact of rapid probing rather than a genuine per-session ceiling. 30 is the largest value with positive evidence of acceptance; 31 is the smallest with positive evidence of refusal. No Coinbase document states this number even now — it is measured venue behaviour, not a documented figure.

So level2 groups symbols at 30 per socket by default, independent of and smaller than ticker's 100 — and, as of this version, that 30 is a supervision option you can change, not only a constant you have to wait on a release to see moved. A universe that needs 5 ticker sockets needs 14 level2 sockets for the same 406-symbol scope (19 total), and every one of them — either channel — is staggered onto the same connect sequence @shard_spacing_ms already describes above, with every ticker shard ordered ahead of every level2 shard so ticker's own boot-time coverage is unaffected. For a 406-symbol universe, that means level2 coverage ramps in over roughly 70 seconds rather than seconds — materially slower than ticker, and an accepted cost against the alternative: order_book coverage that never moved off a handful of symbols at all before this package sized the two channels apart.

A symbol whose level2 subscribe the venue refuses is never marked covered for :order_book — coverage/1 and coverage_by_kind/1 report only what actually arrived, never what was merely asked for — and a refusal reaches subscribe_notices/1 as a :rate_limited Core.Notice every time the venue sends one. The venue has also been observed answering a refusal while still delivering books for part of the same oversized request — an unexplained, dated venue characteristic recorded in docs/reference/coinbase/level2-session-limit.md — and coverage/1 / coverage_by_kind/1 need no special handling for it: both report only symbols that actually delivered a payload, entirely independent of whatever notice accompanied them.

A level2 shard whose membership changes reconciles on its EXISTING socket, unsubscribing departing symbols before subscribing arriving ones. If your universe changes over time — symbols added, removed, or rotated — an already-open level2 shard never gets a new connection just because it gained a symbol; it unsubscribes whatever it is losing, then subscribes whatever it is gaining, on the same session, in that order, every time. The order is load-bearing, not incidental: DpCryptoManagement measured live (2026-09-07) that releasing a batch before requesting the next keeps a session's concurrent count within its own ceiling and gets accepted, while requesting before releasing gets refused — so shrinking always happens before growing, keeping this shard's own concurrent product count at or under level2_pairs_per_socket at every instant of a reconcile, not only at rest. A shard that only loses symbols, or only gains, takes the identical path with the unused half simply empty. This is an internal mechanism, not a new call you make, but a transient send failure on the unsubscribe half can mean a very brief coverage gap for the newly-added symbols while it retries, reported the same way any other failed subscribe is: subscribe_notices/1 receives a :coverage_change notice, and coverage/1 simply does not show them covered yet.

A departure that could not be confirmed sent is retried on the unconditional 60-second cycle, not silently forgotten. If a shard's own unsubscribe keeps failing until this package gives up on it (rare — a socket has to keep refusing to accept the frame at all, not merely refuse the request), those symbols are recorded internally as still owed a release and retried automatically on the same unconditional resubscribe cadence resubscribe_interval_ms already governs, always ordered ahead of that shard's own resubscribe on the same tick. You do not manage this yourself; it exists so a stranded release cannot quietly consume a shard's budget forever. subscribe_notices/1 reports the give-up the same way any other failed subscribe is reported, and reports nothing further once the retry succeeds.

level2_pairs_per_socket — a supervision option, so a venue-side change doesn't need a release

children = [{DpExchange.Coinbase, credentials: my_credentials(), level2_pairs_per_socket: 25}]

Default is 30 — DpCryptoManagement's own measured ceiling, live-bisected against the real venue on 2026-09-06 (see above). Pass a larger or smaller value and every level2 shard chunks to it from boot instead.

Below 1, or not an integer, is refused at start — Feed.start_link/1 (and therefore your own supervision tree's start_link/1) fails with an ArgumentError rather than silently running with a value that could never have sized a shard.

Above 30 is honoured, not capped — with a loud warning, not a silent one. This package cannot verify Coinbase's real ceiling itself (see above — that would be tier-3, authenticated, live probing, which this repo never runs), so it does not get to assume a value you set above today's measurement is wrong. It logs the measured ceiling, the date and source, and the concrete risk before proceeding — stated as what has actually been observed, not more than that. Setting this above 30 means every ordinary level2 subscribe this package sends for that shard is, by itself, a single subscribe over the venue's real limit. DpCryptoManagement measured exactly that shape, 2026-09-07 (issue #22 continuing): one socket, n = 30 accepted, then n = 60 and n = 120 both REFUSED — rate_limited, books=0, nothing delivering, in both ascending and largest-first order. The refusal is wholesale, not truncated to the first 30 — the whole shard's coverage is lost — and the socket survives: no disconnect, Process.alive?/1 true after a 40-second drain, both orderings. That is the same behaviour cumulative overage already showed (two smaller subscribes, refused but alive) — the two shapes this package used to distinguish between now read as one. It also makes the risk harder to notice than the original 2026-08-26 incident implied, not easier: a closed socket announces itself through a disconnect and a reconnect; a refused subscribe on a socket that stays alive announces nothing — no error beyond the :rate_limited Core.Notice, liveness looks perfect, and the shard simply never starts delivering. coverage/1 and coverage_by_kind/1 are what reveal it, because they report only symbols that actually delivered a payload. The 2026-08-26 incident itself (a refusal that did close the socket) stays on record — the 2026-09-07 measurement could not reproduce it, and neither this package nor DpCryptoManagement resolves why; it is left unexplained, not overturned. See docs/reference/coinbase/level2-session-limit.md for the full, dated account. If you are setting this above 30 because you have your own evidence the venue's limit moved, that is exactly what this option is for.

The default is not shrunk for headroom, on purpose. 30 is the actual boundary — 30 accepted, 31 refused, confirmed by interleaving and a contamination check — not merely "the largest value that hasn't failed yet" the way this package's superseded 6 was. Sitting exactly at a boundary that precise is a deliberate choice, not an oversight: see feed.ex's own moduledoc, "level2_pairs_per_socket — a supervision option," for the full reasoning. The risk this package used to flag as still-open here — whether the unconditional 60-second resubscribe could feed a cumulative, attempt-shaped ceiling — was answered 2026-09-07 (see "the ceiling is concurrent, not cumulative" in feed.ex's own moduledoc): repeats do not accumulate, at any shard size. If you want margin below 30 for your own reasons regardless, this option is exactly how you take it — pass a smaller value yourself.

ticker's own shard size (100) has no equivalent option, on purpose: it has no known per-session ceiling to tune against, measured or suspected. This option exists because level2's ceiling is a real, located venue fact a consumer already hit in production, not because "every constant should also be an option."

shard_spacing_ms — the delay between opening successive shards

children = [{DpExchange.Coinbase, credentials: my_credentials(), shard_spacing_ms: 1_000}]

Every new socket this package opens — either channel — takes the next tick of this spacing, so several shards do not connect in the same instant: opening more than one connection at once is a connect burst Coinbase answers with resets (see this file's level2 sections above and feed.ex's own moduledoc for the measured incidents behind that). The same spacing now also staggers reconcile_shard/7's frames when one update_symbols/2 call touches several already-open shards at once, not only when opening a brand-new one.

Default is 5,000ms, unchanged — inherited from the reference fix this package replaced, the same way ticker's 100-per-socket shard size is, not derived from anything measured against this venue.

Below 0, or not an integer, is refused at start — the same shape as level2_pairs_per_socket. 0 itself is honoured, not refused: it schedules every shard in the same instant, which is extreme but not mathematically nonsense the way a negative delay is.

Below the documented connect-rate floor is honoured, not capped — with a loud warning. Coinbase's own Advanced Trade rate-limits page states WebSocket connections are limited to 8 per second per IP, which converts directly into a floor of 125ms (ceil(1_000 / 8)) on this package's own connects. This package cannot verify whether a faster pace is safe for your own network position, so a value below that floor is used as given rather than refused — but it logs the documented floor, its source, and the concrete risk first: connects tighter than the venue's own stated per-IP rate risk the same connect-burst resets this option exists to avoid.

The 5,000ms default is very likely far more conservative than the venue requires — roughly forty times the documented floor — but that is not acted on here; see feed.ex's own moduledoc, "shard_spacing_ms — a supervision option", for why tightening the default is a separate, deliberate decision rather than a side effect of this option's introduction. If you have your own evidence that a tighter pace is safe for your network position, this option is how you take it.

Testing against this package

Use DpExchange.Coinbase.Fake, selected per process through DpExchange.Core.Config. It is a real implementation of the facade that answers from memory, models Coinbase's refusals — unlisted symbols, 12h, the 350 boundary — and passes the same conformance suite as the real adapter.

get_top_of_book/2 errors without opts[:credentials], in the fake too — the one call this venue genuinely requires them for (see above). A test calling it with none gets {:error, {:missing_credentials, :coinbase}} against both the fake and the real client, on purpose: a fake that answered :ok regardless would pass a suite that then refuses in production.

Do not point tests at the live venue. This package's own tier-2 tests do that, tagged and excluded, run by hand. A venue that sees a package polling it on a timer will rate-limit or block.

Two accounts, and only one of them margins a futures position

Advanced Trade's US derivatives sit in an account held with Coinbase Financial Markets; spot sits in one held with Coinbase Inc. get_futures_balance_summary/2 names both — cfm_usd_balance, cbi_usd_balance, total_usd_balance — and sizing a futures position against the total is sizing against money that is not there.

get_positions/1 returns CFM positions. Its :realised_pnl is nil and that is not an omission: the venue publishes daily_realized_pnl, which is what the position realised today, and putting a daily number in a field that means the position's answers a different question under the same name. list_futures_positions/1 returns the venue's own row, where that figure keeps its own name — along with expiration_time, which a future has and Types.Position does not.

A sweep is scheduled, not settled. schedule_futures_sweep/2 queues a move out of the futures account; list_futures_sweeps/2 reports the queue. Omitting the amount sweeps every available excess dollar — the venue's default, not this package's.

INTRADAY_MARGIN_SETTING_UNSPECIFIED is the venue declining to say. It is not _STANDARD, and this package will not map it to one.

Prime is a different product, host and credential

Coinbase Prime is nine custodial staking endpoints. It talks to api.prime.coinbase.com and signs an HMAC under an access key, a passphrase and a signing key — the CDP key pair the rest of this package uses is not accepted there, and two of the three is refused locally rather than sent as a signature over the wrong string. DpExchange.Coinbase.Prime.credentials() is that triple's type.

All nine reach through the facade. stake/3 and unstake/3 are the two that also answer a Core.Venue callback, and they pick a scope only from what you said: a :wallet_id means the wallet, its absence means the portfolio, and :portfolio_id is always required. A portfolio-scoped unstake redeems across every wallet in the portfolio. The other five are Coinbase-specific — no generic callback fits them, so they are plain functions on DpExchange.Coinbase instead:

• query_transaction_validators/3 — the validators a portfolio-scoped staking transaction would touch. A read, despite being a POST: Prime takes the query in the body.
• staking_status/4 — one wallet's staking state. Not what get_staking_balances/1 would answer even if this venue served it: that is every staked position, one per asset; this is one wallet's own state.
• unstake_status/4 — how far a wallet-scoped redemption has got. unstake/3 returns before the asset has unbonded; this is what says whether it is done.
• claim_rewards/4 — moves funds. Claims a wallet's accrued rewards. A write, not a report — it does not say what accrued, only moves what has.
• preview_unstake_wallet/6 — what a wallet-scoped unstake would do, without doing it. Moves nothing.

These are not the CDP Staking API, whose seven endpoints return unsigned transactions for you to sign and broadcast. If you hold one of those, nothing has been staked.

Nothing here has been run. The paths come from the vendor's pages and the signing scheme from its authentication documentation; this repository holds no Prime credential.

Convert: two steps, and no expiry to rely on

quote_conversion/4 holds a rate; commit_conversion/2 accepts it. Advanced Trade states no expiry at all, so expires_at is nil — which means "not stated", never "open-ended". A lapsed quote can be filled at the current rate rather than refused, which is the dangerous outcome because it looks like success and every number in it is real.

Both accounts are re-asked on the commit and even on the read. opts[:from] and opts[:to] are required on commit_conversion/2 and get_conversion/2, and this package fills neither in from the quote: a conversion committed against accounts you did not name happens between the wrong two balances.

Portfolios are addresses, not values

"The account's BTC balance" is not a well-formed question here. list_portfolios/1 names them; get_portfolio_breakdown/3 returns what is inside one, which is a much larger answer. create_account/1 and rename_account/3 reach the portfolio endpoints, because Advanced Trade has no notion of creating an account.

Deleted portfolios stay in the listing. The venue keeps them because old orders still name their ids; filtering them out would make a historical id look like one that never existed.

Fees, volume, and a claim that was wrong

get_fees/2 carries both fee_tier and fee_tier_without_promotion — they differ while a promotion runs, and it can end between two calls. The tax's INCLUSIVE/EXCLUSIVE flag survives too, because the same rate quoted either way is a different amount of money.

get_trade_volume/2 was declared unsupported until 2026-09-01 on the claim that "Advanced Trade does not aggregate" the account's own volume. It does — the transaction summary carries volume_breakdown per volume type. The claim had been made from the market volume endpoint's absence, which answers a different question. The two account totals ride alongside the breakdown rather than being folded in: Advanced Trade volume is documented as non-inclusive of Pro, so adding either to the breakdown double counts.

Every negative here is audited

docs/reference/coinbase/negative-claims.md lists each one with the source and date consulted. Three were wrong and are corrected; the table records what the pattern was, so it is not repeated: each was a true statement about one endpoint, restated as a claim about the venue.