[alexy-os]

Bring github.com/fastygo/codex to Codex data contract v0.4, byte-compatible with @ui8kit/contract 0.2.0 at commit 8299fee (parent 867eb06).

Do not merge-tag v0.4.0 from this PR. Tag only after the contract owner confirms the official vectors.

Official vectors (codex-entry/v1)

Pinned at conformance/contract/ (VERSION commit 8299fee). The published file has 24 cases: 15 ok, 9 error (the request said 17/7; this table follows the actual file). Go matches canonical + digest, or the exact error code, on every case. No divergences to send back.

#	Case	Result
1	control: post-1/en-US with metadata.price	PASS (digest d7ebf2ee…cc4a)
2	key order: reversed top level, whitespace and newlines	PASS (9c71a088…96eb)
3	key order: nested in metadata value, UTF-16 order puts U+FF5E before an astral key	PASS (d68d38dc…bfe3)
4	strings: quote, backslash, newline, U+001F, solidus	PASS (0cf19364…538f)
5	strings: <>& U+2028 U+2029 emoji and Cyrillic stay unescaped	PASS (73d79493…d4c9)
6	numbers: 1250 4.5 0.1 12.50 1e21 1e-7 -0 -1250 9007199254740991	PASS (c578a2a9…2ad9; 1e21 → 1e+21)
7	numbers: 9007199254740993 is an unsafe integer	PASS canonical.unsafe_integer
8	numbers: -9007199254740992 is an unsafe integer	PASS canonical.unsafe_integer
9	empty optional top-level fields are omitted, metadata values are kept	PASS (940b35fa…fe75)
10	metadata private:true is removed, private:false is dropped	PASS (d7ebf2ee…cc4a)
11	metadata with only private items is omitted	PASS (9c71a088…96eb)
12	dates: +03:00 offset is converted to Z, .000Z is dropped	PASS (c03a841c…a512)
13	dates: fractional seconds .5Z	PASS canonical.fractional_seconds
14	dates: date without time	PASS canonical.invalid_date
15	terms are sorted by (taxonomy, term_id) in code point order	PASS (aaa00b45…4c37)
16	origin keeps its order	PASS (3e8f0b66…8e53)
17	unknown top-level field	PASS canonical.unknown_field
18	duplicate key	PASS canonical.duplicate_key
19	duplicate key inside a metadata value	PASS canonical.duplicate_key
20	non-ASCII id	PASS canonical.invalid_id
21	missing locale	PASS canonical.missing_field
22	PHP trap: {} in a json metadata value stays {} (not [])	PASS (915cb2fb…e495)
23	PHP trap: object with keys "0","1" stays an object	PASS (da511da9…7f47)
24	order 0 and pinned false are kept (not empty values)	PASS (fb8a8e68…2ef5)

Runner: canonical.Canonicalize / Digest against conformance/contract/fixtures/vectors/canonical.json.

JCS implementation

canonical/ is a local RFC 8785 port of @ui8kit/contract src/canonical.ts + docs/canonical.md (profile draft v0.4, including the codex-manifest/v2 paragraph). No third-party JCS library. encoding/json is not used for canonical output (it HTML-escapes <>& and \u-escapes U+2028/U+2029). Strict parser rejects duplicate keys and unsafe integers before float64.

Manifest.Digest stays codex-manifest/v1 (Go encoding/json of Canonical()). Manifest.DigestV2 is codex-manifest/v2:sha256: over JCS of Canonical().

Contract decisions vs Go

Topic	Decision	Go
Profile	RFC 8785 JCS over public projection	canonical package
Private metadata	drop private:true; omit private:false	matches vectors 10–11
Sensitive	Entry v0.4 has no sensitive; profile removes nothing on that basis	canonical does not strip; Resource.PublicProjection still does for the Go API
Optional empty	omit top-level null/""/[]/{}; keep metadata.<k>.value	vector 9
Dates	YYYY-MM-DDTHH:MM:SSZ; offsets → Z; .000 dropped; non-zero fraction errors	vectors 12–14
Terms / origin	terms by Unicode code points; origin keeps order	vectors 15–16
Numbers	ES Number.toString; -0→0; 1e21→1e+21	vector 6
Q2 unsafe integer	reject |n| > 2^53-1; 9007199254740993.0 → unsafe_integer	vectors 7–8; article fixture uses 9007199254740991
Q7 localized	means translatable; chrome always localized (no flag); entry.localized_mismatch	validate.CollectionV04
Q8 id	opaque ASCII ^[A-Za-z0-9][A-Za-z0-9._:-]{0,127}$ on id only, not *_id; integer PK <kind>-<n>	Go Validate + canonical; vendored entry.schema.json left as \S
Q9 money	safe integer minor units; negatives allowed; no min; one ISO 4217 currency per record	schema.CheckMoneyCurrency
Unknown rules	error schema.field.rule_unknown	ValidateFieldProfile
Error order	json → unknown → missing → id → fields	canonical.project
null in required	canonical.missing_field	required-field loop
order:0 / pinned:false	kept	vector 24

Pending questions

None for this pin. Q2/Q7/Q8/Q9 are implemented as decided. If a later official vector disagrees, send the case name and Go output back to the contract owner — currently there is nothing to send.

Other v0.4 surface

• Record key (id, locale); chrome is a string; LocalizedText / Locales removed; status adds pending; origin / discussion / order / pinned / format.
• Term + taxonomy label are string + locale; revisions bind (entry_id, locale).
• validate.CollectionV04 ports ISSUE_CODES_V04.
• migrate.EntryJSON / TaxonomyJSON convert v0.3 → v0.4 for a requested locale and reject unsafe integers.
• Vendor refresh: scripts/refresh-ui8kit-contract.sh.
• CI: go test -race.

Verify locally: go test -race -count=1 ./..., go vet ./..., gofmt -l . clean.