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getaca 0.1.6

Setting a session option hands the old one back

• getaca_policy() and getaca_progress() return what their option held before the call, invisibly, so a caller that has to change one for the duration of a function can restore it from on.exit(). Querying is unchanged: with no argument each still reports what is in effect.

Attribution

• The TweetNaCl authors, from whose work src/ed25519.c derives its Curve25519 arithmetic, are listed in Authors@R as contributors. The provenance and what the derived work adds stay in inst/COPYRIGHTS.
• The Description field cites the standards the compiled code implements: FIPS 180-4 for hashing, and the Ed25519 paper and RFC 8032 for signing.

getaca 0.1.5

Drafting a record without moving the file

• Drafting no longer costs disk. A retrieved file is hashed as it arrives and never written down, so a location of any size drafts in one pass with nothing to clean up. keep = TRUE still writes it to the cache, where a later getaca() call finds it.
• registry_draft(local = ) hashes a copy already on your machine and transfers nothing. The record names the location, since that is where users fetch from; where you measured leaves no trace.
• registry_draft(sha256 = ) declares a checksum you already hold and retrieves nothing at all.
• Given both, the local copy is hashed and held to the checksum. That is the check an author wants after a deposit: hashing the download says what users receive, hashing your build says what you uploaded, and a host that recompresses on upload makes those different.
• Both are per-location, named after the locations they belong to or given one for each in order, so a draft over several files can supply a checksum for one of them. A location holding several files takes neither, on the same terms a resource name already does.
• try_one() gained a streaming shape, dest = NULL, which hashes a response as it arrives and reports the digest and the byte count in place of a path.

getaca 0.1.4

Drafting a registry from where the data is

• registry_draft() takes locations and returns a registry() with every checksum filled in. It retrieves each file once and hashes it locally, which is the part of authoring that cannot be done by hand.
• A location is a plain https:// URL or an identifier for a data archive, and which one it is is read off the string. Zenodo, figshare and Dataverse are covered, along with their landing-page URLs. Zenodo and figshare register their own DOI prefixes and are recognised without a lookup; a bare Dataverse DOI is resolved through doi.org, since instances are self-hosted.
• Each archive supplies the licence, the version and a DOI for the artefact. The checksums they publish are read past: all three report md5, from the same host that serves the file.
• A list element gives the mirrors of one resource, so a drafted record can name several locations. keep = TRUE leaves the drafted bytes in the cache instead of transferring them again on the first getaca() call.
• An archive is consulted when a registry is written and never when a user fetches. A drafted registry names ordinary https:// locations.
• jsonlite moves no closer than Suggests, where it already was, and is needed only for the archive handlers.

Resources behind a registration

• A registry may declare the credential a host requires, with auth_host() binding a bearer() or basic() scheme to one host. Both name environment variables: nothing secret enters a registry, a manifest, a digest, a provenance record or an error message. The credential is read at the moment of the request and never stored.
• It travels as an Authorization header, which libcurl withholds from a redirect to another host, and to the declared host only. Hosts match exactly, so a declaration cannot widen where a credential is sent, and credentials are read from the registry the package ships, never from a remote one, for the reason signing keys are.
• A record may list an authenticated mirror beside a public one. The credential goes to the first, and a fetch that falls through to the second succeeds.
• getaca_error_credentials is raised when every mirror that failed answered 401 or 403, naming the variable wanted, whether it is set, and where to register. Those failures previously produced getaca_error_unavailable, whose advice is to connect to a network. Where a host refuses and the declaration names no credential for it, there is no variable to set and the condition’s actor is "author" instead.
• getaca_credentials() reports every variable a package’s declaration reads and whether it is set, without touching the network.

Citing the bytes that were read

• resource(doi = ) records the DOI for an artefact. It renders in the manifest, so a signature covers it, and travels into provenance: getaca_info() shows it and getaca_catalogue() gains a doi column. It routes nothing; locations stay in urls. A https://doi.org/ or doi: prefix is accepted and stripped.

The bar holds one set of columns

• The transferred figure and the rate are right-aligned in the width of the widest value they can take, so a transfer crossing 9.9 MB to 10 MB to 105 MB leaves the total, the rate and the estimate in the columns they started in. Past an exabyte, or an estimate past ten hours, the field is outgrown and the line reflows the way it does whenever it runs out of room.
• human_bytes() chooses the unit and the decimal on the value as it will be rounded rather than as it arrives. sprintf rounds afterwards, so 9.99 kB rendered 10.0 kB against the 10 kB that follows it, a two-column step, and 999.6 kB rendered 1000 kB rather than the megabyte it rounds to.
• The bar budgets each field it will draw. Five columns were reserved for the estimate, which is what 00:00 takes and two short of 4:37:05, so a transfer long enough to want the hours form lost its estimate entirely rather than its bar width.

Under the hood

• REGISTRY_SCHEMA goes to 4, since an older getaca would fetch an authenticated host with no credential and report the refusal as an outage. MANIFEST_FORMAT stays at 1: both new fields render nothing when absent, so every digest already recorded still identifies the state that produced it.
• See dev_notes/adr-010-authenticated-transport.md for why authentication was taken up as transport and DOI resolution was not taken up as a resolver, and dev_notes/adr-011-drafting-registries.md for the archives being read at authoring time instead.

getaca 0.1.3

Archives unpack themselves

• unpack() is a stock processor() for the transformation nearly every declaration of an archive was writing by hand. Attach it with processor = unpack() and getaca() returns the unpacked directory; processed = FALSE still returns the archive it was built from.
• format = "auto" reads the format from the cached file’s name and covers .zip, the tarballs under any compression (.tar, .tar.gz, .tgz, .tar.bz2, .tbz2, .tar.xz, .txz) and a single compressed file (.gz, .bz2, .xz). A compressed file is written under its own name with the extension dropped, so backbone-2026-06.csv.gz unpacks to backbone-2026-06.csv. Name the format for a file whose name does not carry one: unpack("gzip").
• unpack(members = "tables") takes one subtree of a large archive. A member names a file, or a directory and everything under it. A member matching nothing in the archive is an error: getaca hashes the archive and never reads what came out of it, so an empty processed slot would pass every later check.
• The id encodes the settings, because the id is what the cache slot and the registry manifest are keyed on. unpack() is "unpack", unpack("zip") is "unpack-zip", and naming members appends a digest of them, so two records asking for different subsets of one archive cannot resolve to one slot.
• Zero new dependencies. utils::unzip(), utils::untar() and the gzfile()/bzfile()/xzfile() connections are all base R, so Imports is still curl plus three base packages.
• See dev_notes/adr-009-stock-processors.md, which also records what was left out of the equivalent Python API and why.

getaca 0.1.2

Transfers report themselves

• getaca_progress() chooses what a transfer looks like: "bar" redraws a line with the share, the rate and what is left, "line" writes one line to start and one to finish for a log, "none" says nothing, and "auto" picks between the first and the third by whether the session is interactive. Also readable from getaca.progress and GETACA_PROGRESS, and quiet = TRUE on a single getaca() call still overrides all of it.
• reporter() builds your own out of a function of one argument, so a declaring package can report a download in its own voice, or into a Shiny session, or as a row in a log. No dependency: Imports is still curl plus three base packages.
• The events carry what the registry knows and a transfer library cannot: the resource identity, which renders as yourpkg/backbone@2026-09 (part 2 of 3) for a series, the size the declaration states rather than whatever content length the mirror sent, which mirror is being tried, and how much was already on disk when an interrupted transfer resumed. The share a bar shows is therefore right before the first byte arrives and stays right for a host that sends no content length at all.
• A reporter that raises is caught, warned about once and switched off. Reporting is cosmetic and a retrieval is not.

The transfer loop

• getaca drives the transfer over the curl multi interface rather than handing a URL to curl::multi_download(), which is what makes the byte counts reachable at all: multi_download() sets noprogress on the handle after the caller’s options, so a progress callback attached to it never runs. See dev_notes/adr-008-own-transfer-loop.md.
• Resumed transfers now ask for identity encoding. A range request counts bytes of the decoded stream and a compressing server counts encoded ones, and libcurl reports the combination as an error rather than as bytes: against raw.githubusercontent.com a resumed request failed with curl_error_bad_content_encoding and transferred nothing. Every resume from a compressing mirror was silently starting the download over.
• The response status is read before the first byte is written, so the body of a failed request is never written to the partial file. It was previously written and then removed.
• HTTP 416 is distinguished from other refusals. It says the offset asked for is past the end of the file the server holds, so the partial disagrees with upstream and is dropped; any other refusal leaves the bytes an earlier attempt did get.
• A mirror that answers a resume request with the whole file is now detected from the status and written from zero. It previously appended, and cost a full retry once the checksum failed.
• Transfers now send getaca’s user agent. new_handle_for() never set the URL or reached the transfer path at all; the multi interface takes both from the handle.

getaca 0.1.1

Resources that arrive in pieces

• part() and combiner(): a record names either locations for the whole file or the ordered series it is composed from, and sha256 describes the artefact either way. A host that caps file size, and a publisher issuing deltas against a base release, both produce a resource that arrives as a series.
• Each part is verified and stored under its own digest, so a base shared by every version of a resource is transferred once and kept once, and publishing a version costs its consumers the delta rather than the whole file.
• Parts are concatenated unless the record declares a combiner(), which is what a delta format needs. The composed result is held to the record’s own checksum before anything sees it, so a combiner cannot produce bytes the declaration did not already name. That is also why assert_immutable() compares only that checksum: re-splitting a series or moving a piece to another host is a change of route, not of identity.
• getaca_error_composition: every part arrived and matched its own checksum, and combining them produced something else. Nothing failed in transit, so the actor is the author rather than the network.
• resource(file = ): the name the artefact is cached under, for a URL with no useful basename and for composed records, where each URL names a piece rather than the result.
• A part is reached through the entry composed from it, since no version slot names one. A base shared by several versions therefore lives exactly as long as the last version holding it, under the same reachability rule as everything else in the store.
• getaca_catalogue() gains a parts column, 0 where a version is served whole, so what an update costs to fetch is visible before it is fetched.
• part, combiner and file render nothing when absent, so every registry digest recorded before they existed still identifies the state that produced it. The manifest format is unchanged.

getaca 0.1.0

First release.

Dependencies

• Requires R >= 4.0.0 and imports curl (>= 5.0.0), with stats, tools and utils from base R. Zero non-base transitive dependencies, and no LinkingTo. The floor on curl is multi_download(), which is what makes a mirror attempt resumable.
• SHA-256 is implemented in C, in src/sha256.c, covering both the artefact on disk and the manifest in memory. On x86-64 with the SHA extensions and on ARMv8 with the SHA-256 extensions the block compression runs in hardware, which on an i9-14900K hashes at 1.43 GB/s against 0.20 GB/s for tools::sha256sum(): a 4 GB resource is verified in 2.8 s rather than 20 s. Machines without either extension use a portable path that is no slower than what R provides. A digest is a single specified value, so this changes only the time a verification takes; registry digests already recorded stay valid.

Declaration

• resource(): immutable record of exact bytes, with version, mirrors, SHA-256, size, license, upstream identity and optional processor.
• registry(), registry_write(), registry_read(), registry_for(): package-scoped declarations, discovered by convention at inst/getaca/registry.rds.
• registry(current = ): names the channel head, the version a bare request for each resource resolves to. Required for any name declaring more than one version, since version strings are labels and declaration order is not an ordering. A registry that offers a choice and names no head is refused.
• registry_digest(): a registry state is identified by a digest of its own declaration, as "sha256:3f9ac2...". There is no revision number to keep in step, so identity cannot be typed wrong and two states that differ cannot claim to be the same one.
• registry_manifest(): the canonical text the digest is taken over, exported so a digest is never a black box. Two registries that disagree are diffable on the lines that produced the disagreement. Hashing the object itself is not an option, since a processor() closure digests differently on every machine.
• registry_write() stamps created, which orders two states in time. Deliberately outside the digest, so republishing an unchanged registry leaves its identity alone; pass a fixed value to keep a build byte-reproducible.
• A stored form older than this getaca still reads, and only a newer one is refused. Adding a field therefore costs nothing to registries already installed.
• as_registry(): YAML and JSON accepted as authoring formats, gated at call time so neither becomes a hard dependency.
• processor(): post-verification transformation with a stable id, so the derived result gets its own cache slot and provenance.
• getaca_refresh(): forget cached registry state, so a reinstalled declaring package or an updated remote registry is picked up without restarting the session.

Resolution

• getaca_policy(): bundled, current, pinned and offline policies. Resolution collapses to offline under R CMD check.
• resolve_resource() reports the policy in force, and getaca() reads it, so policy = "offline" on a single call keeps that call off the network whatever the session is set to.
• getaca_pin(): freeze current resolution into a local snapshot.
• Remote channels may repair mirrors and publish new versions; redefining a published version is rejected as an invalid registry. Published means the bundled declaration together with whatever this machine has already fetched and verified, so a version that only ever existed remotely is held to its bytes as firmly as one that shipped with the package.

Signing

• registry(keys = ) declares the Ed25519 public keys allowed to sign a package’s remote registry, and registry_keygen(), registry_sign() and registry_verify() are the author-side workflow. Declaring a key makes a signature mandatory under the current policy; declaring none leaves resolution exactly as it was, and no signature is ever fetched.
• The keys trusted are the ones in the registry the package ships, which reaches a user over the R install channel while the remote registry comes from the author’s own host. A signature is worth something because those are two different routes.
• The signature covers registry_manifest(), plus the publication time and an expiry. Binding the time is what stops an old genuine declaration being replayed indefinitely; a state older than the installed one is refused as a rollback.
• A remote that cannot be reached still falls back to the bundled registry with a message. A remote that arrives and fails verification raises getaca_error_signature instead, including when the registry arrives and its signature does not.
• Ed25519 and SHA-512 are implemented in C, in src/ed25519.c and src/sha512.c, checked against RFC 8032 and FIPS 180-4. No new dependency: Imports remains curl plus three base packages.

Retrieval

• getaca(): the single retrieval verb. Returns a local path.
• Resumable transfers into a temporary area, sized and hashed before an atomic move into the cache.
• Directory locking keyed on the declared checksum, so concurrent sessions never duplicate a large transfer or observe a partial one. Two packages declaring the same file wait on each other, and the second finds what the first retrieved.
• Eight classed conditions distinguishing user, author and upstream causes. A transfer that ends short on every mirror raises getaca_error_incomplete, whose action is to retry; mixed causes keep getaca_error_unavailable and list each mirror’s reason.

Verification

• Full SHA-256 on download, cheap size check on access, scheduled re-hash via getaca.verify_days.
• A full re-hash reads the file the caller is handed. Where the filesystem allowed a link that is the blob’s own bytes, and where it refused one the view is an independent copy that nothing else would ever read. A processed slot holds a derived tree the declared checksum does not describe, so it is verified against the artefact it was made from instead.
• A verification whose target cannot be found raises rather than recording a pass. Moving verified_at forward for a check that never ran would put the entry beyond re-verification for good, since every later access would do the same.
• A mismatch is a verdict on bytes rather than on the slot that found it. Where those bytes are ones the store shares, it withdraws verified_at from every other slot naming that digest, so each re-hashes against its own copy on next access. Previously a second package holding the same corrupt bytes kept passing the cheap size check and kept being handed them as verified for the remainder of its own window, up to 90 days. A slot’s own copy and a processed tree indict nothing but themselves.
• A cache hit is measured against the declaration in force as well as against the entry’s own record. A version whose declaration has moved to different bytes raises getaca_error_redeclared naming both checksums, rather than resolving quietly to the copy already held. verify = TRUE asks the same question, so a forced re-hash can no longer confirm bytes against a declaration they no longer match.
• Entry records keep fetched_at, verified_at, checked_at and accessed_at apart.
• Provenance records which declaration state resolved the bytes (registry_digest), when that state was published (registry_created) and which getaca acted on it (getaca_version).

Checks

• getaca_available(), getaca_optional(), getaca_skip_if_unavailable().
• getaca_prefetch() and the GETACA_CACHE environment variable for seeding CI and check runs.

Cache management

• Bytes live once, in a content-addressed store at blobs/sha256/, and a version slot holds a name for them. Two packages declaring the same file keep one copy and separate dependency records. The store holds no metadata: what is still needed is derived from the package indexes rather than counted beside them.
• Everything the store owns is read-only, since a caller writing to a returned path would otherwise damage every package that shares those bytes. A caller needing a writable layout declares a processor(), which gets its own slot.
• getaca_clean() and automatic collection after retrieval: broken material, abandoned transfers, superseded versions past retention, LRU eviction only above the size ceiling, and finally bytes no declaration references.
• The size ceiling measures what the cache occupies. Shared bytes count once, so two packages declaring one 4 GB file no longer count 8 GB against it.
• getaca_keep() to exempt a resource.
• getaca_catalogue(): one table covering what packages declare and what the cache holds, including declared resources never downloaded and cached versions no longer declared. A current column marks the version a bare request resolves to.
• getaca_info(): full provenance for one cached resource.

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