WIP: Save agent roles integration work before CHORUS rebrand

- Agent roles and coordination features - Chat API integration testing - New configuration and workspace management 🤖 Generated with [Claude Code](https://claude.ai/code) Co-Authored-By: Claude <noreply@anthropic.com>
2025-08-01 02:21:11 +10:00
parent 81b473d48f
commit 5978a0b8f5
3713 changed files with 1103925 additions and 59 deletions
--- a/vendor/github.com/ipfs/go-cid/cid.go
+++ b/vendor/github.com/ipfs/go-cid/cid.go
@@ -0,0 +1,817 @@
+// Package cid implements the Content-IDentifiers specification
+// (https://github.com/ipld/cid) in Go. CIDs are
+// self-describing content-addressed identifiers useful for
+// distributed information systems. CIDs are used in the IPFS
+// (https://ipfs.io) project ecosystem.
+//
+// CIDs have two major versions. A CIDv0 corresponds to a multihash of type
+// DagProtobuf, is deprecated and exists for compatibility reasons. Usually,
+// CIDv1 should be used.
+//
+// A CIDv1 has four parts:
+//
+//	<cidv1> ::= <multibase-prefix><cid-version><multicodec-packed-content-type><multihash-content-address>
+//
+// As shown above, the CID implementation relies heavily on Multiformats,
+// particularly Multibase
+// (https://github.com/multiformats/go-multibase), Multicodec
+// (https://github.com/multiformats/multicodec) and Multihash
+// implementations (https://github.com/multiformats/go-multihash).
+package cid
+
+import (
+	"bytes"
+	"encoding"
+	"encoding/binary"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"strings"
+
+	mbase "github.com/multiformats/go-multibase"
+	mh "github.com/multiformats/go-multihash"
+	varint "github.com/multiformats/go-varint"
+)
+
+// UnsupportedVersionString just holds an error message
+const UnsupportedVersionString = "<unsupported cid version>"
+
+// ErrInvalidCid is an error that indicates that a CID is invalid.
+type ErrInvalidCid struct {
+	Err error
+}
+
+func (e ErrInvalidCid) Error() string {
+	return fmt.Sprintf("invalid cid: %s", e.Err)
+}
+
+func (e ErrInvalidCid) Unwrap() error {
+	return e.Err
+}
+
+func (e ErrInvalidCid) Is(err error) bool {
+	switch err.(type) {
+	case ErrInvalidCid, *ErrInvalidCid:
+		return true
+	default:
+		return false
+	}
+}
+
+var (
+	// ErrCidTooShort means that the cid passed to decode was not long
+	// enough to be a valid Cid
+	ErrCidTooShort = ErrInvalidCid{errors.New("cid too short")}
+
+	// ErrInvalidEncoding means that selected encoding is not supported
+	// by this Cid version
+	ErrInvalidEncoding = errors.New("invalid base encoding")
+)
+
+// Consts below are DEPRECATED and left only for legacy reasons:
+// <https://github.com/ipfs/go-cid/pull/137>
+// Modern code should use consts from go-multicodec instead:
+// <https://github.com/multiformats/go-multicodec>
+const (
+	// common ones
+	Raw         = 0x55
+	DagProtobuf = 0x70   // https://ipld.io/docs/codecs/known/dag-pb/
+	DagCBOR     = 0x71   // https://ipld.io/docs/codecs/known/dag-cbor/
+	DagJSON     = 0x0129 // https://ipld.io/docs/codecs/known/dag-json/
+	Libp2pKey   = 0x72   // https://github.com/libp2p/specs/blob/master/peer-ids/peer-ids.md#peer-ids
+
+	// other
+	GitRaw                = 0x78
+	DagJOSE               = 0x85 // https://ipld.io/specs/codecs/dag-jose/spec/
+	EthBlock              = 0x90
+	EthBlockList          = 0x91
+	EthTxTrie             = 0x92
+	EthTx                 = 0x93
+	EthTxReceiptTrie      = 0x94
+	EthTxReceipt          = 0x95
+	EthStateTrie          = 0x96
+	EthAccountSnapshot    = 0x97
+	EthStorageTrie        = 0x98
+	BitcoinBlock          = 0xb0
+	BitcoinTx             = 0xb1
+	ZcashBlock            = 0xc0
+	ZcashTx               = 0xc1
+	DecredBlock           = 0xe0
+	DecredTx              = 0xe1
+	DashBlock             = 0xf0
+	DashTx                = 0xf1
+	FilCommitmentUnsealed = 0xf101
+	FilCommitmentSealed   = 0xf102
+)
+
+// tryNewCidV0 tries to convert a multihash into a CIDv0 CID and returns an
+// error on failure.
+func tryNewCidV0(mhash mh.Multihash) (Cid, error) {
+	// Need to make sure hash is valid for CidV0 otherwise we will
+	// incorrectly detect it as CidV1 in the Version() method
+	dec, err := mh.Decode(mhash)
+	if err != nil {
+		return Undef, ErrInvalidCid{err}
+	}
+	if dec.Code != mh.SHA2_256 || dec.Length != 32 {
+		return Undef, ErrInvalidCid{fmt.Errorf("invalid hash for cidv0 %d-%d", dec.Code, dec.Length)}
+	}
+	return Cid{string(mhash)}, nil
+}
+
+// NewCidV0 returns a Cid-wrapped multihash.
+// They exist to allow IPFS to work with Cids while keeping
+// compatibility with the plain-multihash format used used in IPFS.
+// NewCidV1 should be used preferentially.
+//
+// Panics if the multihash isn't sha2-256.
+func NewCidV0(mhash mh.Multihash) Cid {
+	c, err := tryNewCidV0(mhash)
+	if err != nil {
+		panic(err)
+	}
+	return c
+}
+
+// NewCidV1 returns a new Cid using the given multicodec-packed
+// content type.
+//
+// Panics if the multihash is invalid.
+func NewCidV1(codecType uint64, mhash mh.Multihash) Cid {
+	hashlen := len(mhash)
+
+	// Two 8 bytes (max) numbers plus hash.
+	// We use strings.Builder to only allocate once.
+	var b strings.Builder
+	b.Grow(1 + varint.UvarintSize(codecType) + hashlen)
+
+	b.WriteByte(1)
+
+	var buf [binary.MaxVarintLen64]byte
+	n := varint.PutUvarint(buf[:], codecType)
+	b.Write(buf[:n])
+
+	cn, _ := b.Write(mhash)
+	if cn != hashlen {
+		panic("copy hash length is inconsistent")
+	}
+
+	return Cid{b.String()}
+}
+
+var (
+	_ encoding.BinaryMarshaler   = Cid{}
+	_ encoding.BinaryUnmarshaler = (*Cid)(nil)
+	_ encoding.TextMarshaler     = Cid{}
+	_ encoding.TextUnmarshaler   = (*Cid)(nil)
+)
+
+// Cid represents a self-describing content addressed
+// identifier. It is formed by a Version, a Codec (which indicates
+// a multicodec-packed content type) and a Multihash.
+type Cid struct{ str string }
+
+// Undef can be used to represent a nil or undefined Cid, using Cid{}
+// directly is also acceptable.
+var Undef = Cid{}
+
+// Defined returns true if a Cid is defined
+// Calling any other methods on an undefined Cid will result in
+// undefined behavior.
+func (c Cid) Defined() bool {
+	return c.str != ""
+}
+
+// Parse is a short-hand function to perform Decode, Cast etc... on
+// a generic interface{} type.
+func Parse(v interface{}) (Cid, error) {
+	switch v2 := v.(type) {
+	case string:
+		if strings.Contains(v2, "/ipfs/") {
+			return Decode(strings.Split(v2, "/ipfs/")[1])
+		}
+		return Decode(v2)
+	case []byte:
+		return Cast(v2)
+	case mh.Multihash:
+		return tryNewCidV0(v2)
+	case Cid:
+		return v2, nil
+	default:
+		return Undef, ErrInvalidCid{fmt.Errorf("can't parse %+v as Cid", v2)}
+	}
+}
+
+// MustParse calls Parse but will panic on error.
+func MustParse(v interface{}) Cid {
+	c, err := Parse(v)
+	if err != nil {
+		panic(err)
+	}
+	return c
+}
+
+// Decode parses a Cid-encoded string and returns a Cid object.
+// For CidV1, a Cid-encoded string is primarily a multibase string:
+//
+//	<multibase-type-code><base-encoded-string>
+//
+// The base-encoded string represents a:
+//
+// <version><codec-type><multihash>
+//
+// Decode will also detect and parse CidV0 strings. Strings
+// starting with "Qm" are considered CidV0 and treated directly
+// as B58-encoded multihashes.
+func Decode(v string) (Cid, error) {
+	if len(v) < 2 {
+		return Undef, ErrCidTooShort
+	}
+
+	if len(v) == 46 && v[:2] == "Qm" {
+		hash, err := mh.FromB58String(v)
+		if err != nil {
+			return Undef, ErrInvalidCid{err}
+		}
+
+		return tryNewCidV0(hash)
+	}
+
+	_, data, err := mbase.Decode(v)
+	if err != nil {
+		return Undef, ErrInvalidCid{err}
+	}
+
+	return Cast(data)
+}
+
+// Extract the encoding from a Cid.  If Decode on the same string did
+// not return an error neither will this function.
+func ExtractEncoding(v string) (mbase.Encoding, error) {
+	if len(v) < 2 {
+		return -1, ErrCidTooShort
+	}
+
+	if len(v) == 46 && v[:2] == "Qm" {
+		return mbase.Base58BTC, nil
+	}
+
+	encoding := mbase.Encoding(v[0])
+
+	// check encoding is valid
+	_, err := mbase.NewEncoder(encoding)
+	if err != nil {
+		return -1, ErrInvalidCid{err}
+	}
+
+	return encoding, nil
+}
+
+// Cast takes a Cid data slice, parses it and returns a Cid.
+// For CidV1, the data buffer is in the form:
+//
+//	<version><codec-type><multihash>
+//
+// CidV0 are also supported. In particular, data buffers starting
+// with length 34 bytes, which starts with bytes [18,32...] are considered
+// binary multihashes.
+//
+// Please use decode when parsing a regular Cid string, as Cast does not
+// expect multibase-encoded data. Cast accepts the output of Cid.Bytes().
+func Cast(data []byte) (Cid, error) {
+	nr, c, err := CidFromBytes(data)
+	if err != nil {
+		return Undef, ErrInvalidCid{err}
+	}
+
+	if nr != len(data) {
+		return Undef, ErrInvalidCid{fmt.Errorf("trailing bytes in data buffer passed to cid Cast")}
+	}
+
+	return c, nil
+}
+
+// UnmarshalBinary is equivalent to Cast(). It implements the
+// encoding.BinaryUnmarshaler interface.
+func (c *Cid) UnmarshalBinary(data []byte) error {
+	casted, err := Cast(data)
+	if err != nil {
+		return err
+	}
+	c.str = casted.str
+	return nil
+}
+
+// UnmarshalText is equivalent to Decode(). It implements the
+// encoding.TextUnmarshaler interface.
+func (c *Cid) UnmarshalText(text []byte) error {
+	decodedCid, err := Decode(string(text))
+	if err != nil {
+		return err
+	}
+	c.str = decodedCid.str
+	return nil
+}
+
+// Version returns the Cid version.
+func (c Cid) Version() uint64 {
+	if len(c.str) == 34 && c.str[0] == 18 && c.str[1] == 32 {
+		return 0
+	}
+	return 1
+}
+
+// Type returns the multicodec-packed content type of a Cid.
+func (c Cid) Type() uint64 {
+	if c.Version() == 0 {
+		return DagProtobuf
+	}
+	_, n, _ := uvarint(c.str)
+	codec, _, _ := uvarint(c.str[n:])
+	return codec
+}
+
+// String returns the default string representation of a
+// Cid. Currently, Base32 is used for CIDV1 as the encoding for the
+// multibase string, Base58 is used for CIDV0.
+func (c Cid) String() string {
+	switch c.Version() {
+	case 0:
+		return c.Hash().B58String()
+	case 1:
+		mbstr, err := mbase.Encode(mbase.Base32, c.Bytes())
+		if err != nil {
+			panic("should not error with hardcoded mbase: " + err.Error())
+		}
+
+		return mbstr
+	default:
+		panic("not possible to reach this point")
+	}
+}
+
+// String returns the string representation of a Cid
+// encoded is selected base
+func (c Cid) StringOfBase(base mbase.Encoding) (string, error) {
+	switch c.Version() {
+	case 0:
+		if base != mbase.Base58BTC {
+			return "", ErrInvalidEncoding
+		}
+		return c.Hash().B58String(), nil
+	case 1:
+		return mbase.Encode(base, c.Bytes())
+	default:
+		panic("not possible to reach this point")
+	}
+}
+
+// Encode return the string representation of a Cid in a given base
+// when applicable.  Version 0 Cid's are always in Base58 as they do
+// not take a multibase prefix.
+func (c Cid) Encode(base mbase.Encoder) string {
+	switch c.Version() {
+	case 0:
+		return c.Hash().B58String()
+	case 1:
+		return base.Encode(c.Bytes())
+	default:
+		panic("not possible to reach this point")
+	}
+}
+
+// Hash returns the multihash contained by a Cid.
+func (c Cid) Hash() mh.Multihash {
+	bytes := c.Bytes()
+
+	if c.Version() == 0 {
+		return mh.Multihash(bytes)
+	}
+
+	// skip version length
+	_, n1, _ := varint.FromUvarint(bytes)
+	// skip codec length
+	_, n2, _ := varint.FromUvarint(bytes[n1:])
+
+	return mh.Multihash(bytes[n1+n2:])
+}
+
+// Bytes returns the byte representation of a Cid.
+// The output of bytes can be parsed back into a Cid
+// with Cast().
+//
+// If c.Defined() == false, it return a nil slice and may not
+// be parsable with Cast().
+func (c Cid) Bytes() []byte {
+	if !c.Defined() {
+		return nil
+	}
+	return []byte(c.str)
+}
+
+// ByteLen returns the length of the CID in bytes.
+// It's equivalent to `len(c.Bytes())`, but works without an allocation,
+// and should therefore be preferred.
+//
+// (See also the WriteTo method for other important operations that work without allocation.)
+func (c Cid) ByteLen() int {
+	return len(c.str)
+}
+
+// WriteBytes writes the CID bytes to the given writer.
+// This method works without incurring any allocation.
+//
+// (See also the ByteLen method for other important operations that work without allocation.)
+func (c Cid) WriteBytes(w io.Writer) (int, error) {
+	n, err := io.WriteString(w, c.str)
+	if err != nil {
+		return n, err
+	}
+	if n != len(c.str) {
+		return n, fmt.Errorf("failed to write entire cid string")
+	}
+	return n, nil
+}
+
+// MarshalBinary is equivalent to Bytes(). It implements the
+// encoding.BinaryMarshaler interface.
+func (c Cid) MarshalBinary() ([]byte, error) {
+	return c.Bytes(), nil
+}
+
+// MarshalText is equivalent to String(). It implements the
+// encoding.TextMarshaler interface.
+func (c Cid) MarshalText() ([]byte, error) {
+	return []byte(c.String()), nil
+}
+
+// Equals checks that two Cids are the same.
+// In order for two Cids to be considered equal, the
+// Version, the Codec and the Multihash must match.
+func (c Cid) Equals(o Cid) bool {
+	return c == o
+}
+
+// UnmarshalJSON parses the JSON representation of a Cid.
+func (c *Cid) UnmarshalJSON(b []byte) error {
+	if len(b) < 2 {
+		return ErrInvalidCid{fmt.Errorf("invalid cid json blob")}
+	}
+	obj := struct {
+		CidTarget string `json:"/"`
+	}{}
+	objptr := &obj
+	err := json.Unmarshal(b, &objptr)
+	if err != nil {
+		return ErrInvalidCid{err}
+	}
+	if objptr == nil {
+		*c = Cid{}
+		return nil
+	}
+
+	if obj.CidTarget == "" {
+		return ErrInvalidCid{fmt.Errorf("cid was incorrectly formatted")}
+	}
+
+	out, err := Decode(obj.CidTarget)
+	if err != nil {
+		return ErrInvalidCid{err}
+	}
+
+	*c = out
+
+	return nil
+}
+
+// MarshalJSON procudes a JSON representation of a Cid, which looks as follows:
+//
+//	{ "/": "<cid-string>" }
+//
+// Note that this formatting comes from the IPLD specification
+// (https://github.com/ipld/specs/tree/master/ipld)
+func (c Cid) MarshalJSON() ([]byte, error) {
+	if !c.Defined() {
+		return []byte("null"), nil
+	}
+	return []byte(fmt.Sprintf("{\"/\":\"%s\"}", c.String())), nil
+}
+
+// KeyString returns the binary representation of the Cid as a string
+func (c Cid) KeyString() string {
+	return c.str
+}
+
+// Loggable returns a Loggable (as defined by
+// https://godoc.org/github.com/ipfs/go-log).
+func (c Cid) Loggable() map[string]interface{} {
+	return map[string]interface{}{
+		"cid": c,
+	}
+}
+
+// Prefix builds and returns a Prefix out of a Cid.
+func (c Cid) Prefix() Prefix {
+	if c.Version() == 0 {
+		return Prefix{
+			MhType:   mh.SHA2_256,
+			MhLength: 32,
+			Version:  0,
+			Codec:    DagProtobuf,
+		}
+	}
+
+	offset := 0
+	version, n, _ := uvarint(c.str[offset:])
+	offset += n
+	codec, n, _ := uvarint(c.str[offset:])
+	offset += n
+	mhtype, n, _ := uvarint(c.str[offset:])
+	offset += n
+	mhlen, _, _ := uvarint(c.str[offset:])
+
+	return Prefix{
+		MhType:   mhtype,
+		MhLength: int(mhlen),
+		Version:  version,
+		Codec:    codec,
+	}
+}
+
+// Prefix represents all the metadata of a Cid,
+// that is, the Version, the Codec, the Multihash type
+// and the Multihash length. It does not contains
+// any actual content information.
+// NOTE: The use -1 in MhLength to mean default length is deprecated,
+//
+//	use the V0Builder or V1Builder structures instead
+type Prefix struct {
+	Version  uint64
+	Codec    uint64
+	MhType   uint64
+	MhLength int
+}
+
+// Sum uses the information in a prefix to perform a multihash.Sum()
+// and return a newly constructed Cid with the resulting multihash.
+func (p Prefix) Sum(data []byte) (Cid, error) {
+	length := p.MhLength
+	if p.MhType == mh.IDENTITY {
+		length = -1
+	}
+
+	if p.Version == 0 && (p.MhType != mh.SHA2_256 ||
+		(p.MhLength != 32 && p.MhLength != -1)) {
+
+		return Undef, ErrInvalidCid{fmt.Errorf("invalid v0 prefix")}
+	}
+
+	hash, err := mh.Sum(data, p.MhType, length)
+	if err != nil {
+		return Undef, ErrInvalidCid{err}
+	}
+
+	switch p.Version {
+	case 0:
+		return NewCidV0(hash), nil
+	case 1:
+		return NewCidV1(p.Codec, hash), nil
+	default:
+		return Undef, ErrInvalidCid{fmt.Errorf("invalid cid version")}
+	}
+}
+
+// Bytes returns a byte representation of a Prefix. It looks like:
+//
+//	<version><codec><mh-type><mh-length>
+func (p Prefix) Bytes() []byte {
+	size := varint.UvarintSize(p.Version)
+	size += varint.UvarintSize(p.Codec)
+	size += varint.UvarintSize(p.MhType)
+	size += varint.UvarintSize(uint64(p.MhLength))
+
+	buf := make([]byte, size)
+	n := varint.PutUvarint(buf, p.Version)
+	n += varint.PutUvarint(buf[n:], p.Codec)
+	n += varint.PutUvarint(buf[n:], p.MhType)
+	n += varint.PutUvarint(buf[n:], uint64(p.MhLength))
+	if n != size {
+		panic("size mismatch")
+	}
+	return buf
+}
+
+// PrefixFromBytes parses a Prefix-byte representation onto a
+// Prefix.
+func PrefixFromBytes(buf []byte) (Prefix, error) {
+	r := bytes.NewReader(buf)
+	vers, err := varint.ReadUvarint(r)
+	if err != nil {
+		return Prefix{}, ErrInvalidCid{err}
+	}
+
+	codec, err := varint.ReadUvarint(r)
+	if err != nil {
+		return Prefix{}, ErrInvalidCid{err}
+	}
+
+	mhtype, err := varint.ReadUvarint(r)
+	if err != nil {
+		return Prefix{}, ErrInvalidCid{err}
+	}
+
+	mhlen, err := varint.ReadUvarint(r)
+	if err != nil {
+		return Prefix{}, ErrInvalidCid{err}
+	}
+
+	return Prefix{
+		Version:  vers,
+		Codec:    codec,
+		MhType:   mhtype,
+		MhLength: int(mhlen),
+	}, nil
+}
+
+func CidFromBytes(data []byte) (int, Cid, error) {
+	if len(data) > 2 && data[0] == mh.SHA2_256 && data[1] == 32 {
+		if len(data) < 34 {
+			return 0, Undef, ErrInvalidCid{fmt.Errorf("not enough bytes for cid v0")}
+		}
+
+		h, err := mh.Cast(data[:34])
+		if err != nil {
+			return 0, Undef, ErrInvalidCid{err}
+		}
+
+		return 34, Cid{string(h)}, nil
+	}
+
+	vers, n, err := varint.FromUvarint(data)
+	if err != nil {
+		return 0, Undef, ErrInvalidCid{err}
+	}
+
+	if vers != 1 {
+		return 0, Undef, ErrInvalidCid{fmt.Errorf("expected 1 as the cid version number, got: %d", vers)}
+	}
+
+	_, cn, err := varint.FromUvarint(data[n:])
+	if err != nil {
+		return 0, Undef, ErrInvalidCid{err}
+	}
+
+	mhnr, _, err := mh.MHFromBytes(data[n+cn:])
+	if err != nil {
+		return 0, Undef, ErrInvalidCid{err}
+	}
+
+	l := n + cn + mhnr
+
+	return l, Cid{string(data[0:l])}, nil
+}
+
+func toBufByteReader(r io.Reader, dst []byte) *bufByteReader {
+	// If the reader already implements ByteReader, use it directly.
+	// Otherwise, use a fallback that does 1-byte Reads.
+	if br, ok := r.(io.ByteReader); ok {
+		return &bufByteReader{direct: br, dst: dst}
+	}
+	return &bufByteReader{fallback: r, dst: dst}
+}
+
+type bufByteReader struct {
+	direct   io.ByteReader
+	fallback io.Reader
+
+	dst []byte
+}
+
+func (r *bufByteReader) ReadByte() (byte, error) {
+	// The underlying reader has ReadByte; use it.
+	if br := r.direct; br != nil {
+		b, err := br.ReadByte()
+		if err != nil {
+			return 0, err
+		}
+		r.dst = append(r.dst, b)
+		return b, nil
+	}
+
+	// Fall back to a one-byte Read.
+	// TODO: consider reading straight into dst,
+	// once we have benchmarks and if they prove that to be faster.
+	var p [1]byte
+	if _, err := io.ReadFull(r.fallback, p[:]); err != nil {
+		return 0, err
+	}
+	r.dst = append(r.dst, p[0])
+	return p[0], nil
+}
+
+// CidFromReader reads a precise number of bytes for a CID from a given reader.
+// It returns the number of bytes read, the CID, and any error encountered.
+// The number of bytes read is accurate even if a non-nil error is returned.
+//
+// It's recommended to supply a reader that buffers and implements io.ByteReader,
+// as CidFromReader has to do many single-byte reads to decode varints.
+// If the argument only implements io.Reader, single-byte Read calls are used instead.
+//
+// If the Reader is found to yield zero bytes, an io.EOF error is returned directly, in all
+// other error cases, an ErrInvalidCid, wrapping the original error, is returned.
+func CidFromReader(r io.Reader) (int, Cid, error) {
+	// 64 bytes is enough for any CIDv0,
+	// and it's enough for most CIDv1s in practice.
+	// If the digest is too long, we'll allocate more.
+	br := toBufByteReader(r, make([]byte, 0, 64))
+
+	// We read the first varint, to tell if this is a CIDv0 or a CIDv1.
+	// The varint package wants a io.ByteReader, so we must wrap our io.Reader.
+	vers, err := varint.ReadUvarint(br)
+	if err != nil {
+		if err == io.EOF {
+			// First-byte read in ReadUvarint errors with io.EOF, so reader has no data.
+			// Subsequent reads with an EOF will return io.ErrUnexpectedEOF and be wrapped here.
+			return 0, Undef, err
+		}
+		return len(br.dst), Undef, ErrInvalidCid{err}
+	}
+
+	// If we have a CIDv0, read the rest of the bytes and cast the buffer.
+	if vers == mh.SHA2_256 {
+		if n, err := io.ReadFull(r, br.dst[1:34]); err != nil {
+			return len(br.dst) + n, Undef, ErrInvalidCid{err}
+		}
+
+		br.dst = br.dst[:34]
+		h, err := mh.Cast(br.dst)
+		if err != nil {
+			return len(br.dst), Undef, ErrInvalidCid{err}
+		}
+
+		return len(br.dst), Cid{string(h)}, nil
+	}
+
+	if vers != 1 {
+		return len(br.dst), Undef, ErrInvalidCid{fmt.Errorf("expected 1 as the cid version number, got: %d", vers)}
+	}
+
+	// CID block encoding multicodec.
+	_, err = varint.ReadUvarint(br)
+	if err != nil {
+		return len(br.dst), Undef, ErrInvalidCid{err}
+	}
+
+	// We could replace most of the code below with go-multihash's ReadMultihash.
+	// Note that it would save code, but prevent reusing buffers.
+	// Plus, we already have a ByteReader now.
+	mhStart := len(br.dst)
+
+	// Multihash hash function code.
+	_, err = varint.ReadUvarint(br)
+	if err != nil {
+		return len(br.dst), Undef, ErrInvalidCid{err}
+	}
+
+	// Multihash digest length.
+	mhl, err := varint.ReadUvarint(br)
+	if err != nil {
+		return len(br.dst), Undef, ErrInvalidCid{err}
+	}
+
+	// Refuse to make large allocations to prevent OOMs due to bugs.
+	const maxDigestAlloc = 32 << 20 // 32MiB
+	if mhl > maxDigestAlloc {
+		return len(br.dst), Undef, ErrInvalidCid{fmt.Errorf("refusing to allocate %d bytes for a digest", mhl)}
+	}
+
+	// Fine to convert mhl to int, given maxDigestAlloc.
+	prefixLength := len(br.dst)
+	cidLength := prefixLength + int(mhl)
+	if cidLength > cap(br.dst) {
+		// If the multihash digest doesn't fit in our initial 64 bytes,
+		// efficiently extend the slice via append+make.
+		br.dst = append(br.dst, make([]byte, cidLength-len(br.dst))...)
+	} else {
+		// The multihash digest fits inside our buffer,
+		// so just extend its capacity.
+		br.dst = br.dst[:cidLength]
+	}
+
+	if n, err := io.ReadFull(r, br.dst[prefixLength:cidLength]); err != nil {
+		// We can't use len(br.dst) here,
+		// as we've only read n bytes past prefixLength.
+		return prefixLength + n, Undef, ErrInvalidCid{err}
+	}
+
+	// This simply ensures the multihash is valid.
+	// TODO: consider removing this bit, as it's probably redundant;
+	// for now, it helps ensure consistency with CidFromBytes.
+	_, _, err = mh.MHFromBytes(br.dst[mhStart:])
+	if err != nil {
+		return len(br.dst), Undef, ErrInvalidCid{err}
+	}
+
+	return len(br.dst), Cid{string(br.dst)}, nil
+}