PureYAML/CHANGELOG.md

Changelog

All notable changes to PureYAML are documented in this file.

The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

[Unreleased]

Added

• The validator is now configurable by rule identity, per the validation-rules idiom: withoutValidating(_ description:) removes a rule by its description (the removal identity, so descriptions must be unique and stable), and validationDescriptions lists the active rules in application order. A configuration-pin test asserts the exact descriptions of the blank and default validators, so adding, removing, or rewording a rule is a deliberate change.
• A validation-coverage gate (scripts/check-validation-coverage.sh, wired into scripts/check-all.sh and CI) enforcing the validation-rules discipline that every public type is either validated or excluded. It enumerates the public surface from the compiler symbol graph (the authoritative source, not a grep heuristic) and fails the build, by name, if any public type is missing from scripts/validation-coverage.tsv or any manifest entry is no longer public. All 58 public types are classified: the value models carrying a runtime invariant (mapping-key uniqueness) are validated, and the caseless namespaces, closed sum types, data-transfer values, error types, and engine/machinery are excluded with a one-line reason each. This is the first phase of adopting the OpenAPIKit-style validation idiom; the type-directed Validation<Subject> framework that backs the validated entries follows.
• An opt-in conformance harness against the official YAML test-suite, the canonical YAML 1.2 corpus (Tests/YAMLTestSuiteConformanceTests.swift, scripts/fetch-yaml-test-suite.sh). Gated behind PUREYAML_RUN_YAML_TEST_SUITE=1 and a separate fetch, so the data is never vendored. It reports two levels: parse-level (a should-parse case must parse; a should-error case must be rejected; failures histogrammed by cause) and the stricter, honest value-level, comparing the parsed tree to each case's in.json. Value-level baseline: 130/170 (76.5%) of comparable single-document cases, exposing 40 documents that parse without error but to the wrong tree (e.g. double-quoted line folding, scalar resolution, block-scalar indentation) which parse-level cannot see. This turns "best YAML library" from an assertion into a tracked number.

Fixed

• Content after a document-end marker (...) now begins a new bare document. A stream such as --- scalar / ... / key: value or a / ... / b is two documents, but the scanner rejected the content and the parser expected the document to end at the marker. The scanner now reopens the stream after ..., and the document loop returns at a ... so the outer loop parses the next document. A trailing ... with nothing after it still leaves a single document. Lifts official test-suite parse-level conformance from 288/333 (86.5%) to 289/333 (86.8%), with no regression.
• An anchor or tag with no node after it now denotes an empty node. A property always attaches to a node and an empty node is allowed, so &anchor alone, key: &a, or a !!str with nothing after it (x: !!str is the empty string, x: !!null is null) is the property applied to a null node rather than a missing-node error. A real tagged or anchored value is unaffected. Lifts official test-suite parse-level conformance from 287/333 (86.2%) to 288/333 (86.5%) and value-level by one.
• An implicit null mapping key is now parsed. A : that opens a line with no key before it (: value, a bare :, or a null key among other entries) is an entry with a null key, which the parser previously rejected as a missing node. The scanner synthesizes the empty key, tracking a pending explicit ? key so that an explicit key's value indicator on the next line, including after a flow complex key (? {a: b} then : c), is not mistaken for a null key. Lifts official test-suite parse-level conformance from 283/333 (85.0%) to 287/333 (86.2%), with no regression.
• A directive after a document-end marker (...) now begins the next document instead of being rejected. A multi-document stream where each document carries its own directives (%TAG ... / --- doc / ... / %TAG ... / --- doc) is now accepted, since a directive following ... opens the next document's directive section. A directive after document content within the same document is still rejected, and a directive after ... still requires its own ---. Lifts official test-suite parse-level conformance from 278/333 (83.5%) to 283/333 (85.0%), with no regression.
• A block sequence entry can no longer follow a flow collection that closed earlier on the same line (- { y: z }- invalid, - [a] - b); the entry would begin a sequence inline after a complete node. The scanner now tracks a top-level flow close on the current line and rejects a block entry after it, while a nested block entry (- -, which has no preceding flow close), a flow collection on its own line, and nested flow collections are unaffected. Lifts official test-suite parse-level conformance from 276/333 (82.9%) to 277/333 (83.2%), with no regression.
• A mapping value's anchor or tag on the line below the key must now be indented past the key. A property at the key's own indentation is ambiguous with a sibling and is rejected, whether it is the only property (seq: then &anchor in column 1) or a later one after an inline first (key: &x then a !!tag in column 1). An inline property, a property indented under the key, and a block sequence at the key's indent (which carries no property) stay valid. Lifts official test-suite parse-level conformance from 275/333 (82.6%) to 278/333 (83.5%), with no regression.
• A - immediately before a flow indicator is no longer treated as a scalar. In a flow collection a - that begins a plain scalar must be followed by a non-indicator character, so [-], [-, -], and {a: -} are now rejected. A dash followed by ordinary content is unaffected: negative numbers ([-1, -2]), a dash inside a scalar (a-b), a dash starting a word (-x), and a quoted dash all stay valid. Lifts official test-suite parse-level conformance from 273/333 (82.0%) to 275/333 (82.6%), with no regression.
• A block scalar leading blank line that is more indented than the content is now rejected. The spec forbids a leading empty line from containing more spaces than the first non-empty line, so a block scalar whose blank lines are wider than its content (| then a 5-space blank then 2-space content) no longer parses. Indentation is counted in spaces, not tab-expanded width, so a tab on a blank line (␣\t) is not treated as a deeper indent. Leading blanks within the content indent are unaffected. Lifts official test-suite parse-level conformance from 270/333 (81.1%) to 273/333 (82.0%), with no regression.
• A document marker line (--- or ...) inside a multi-line quoted scalar is now rejected. Such a line is ambiguous with a document boundary, so the spec forbids it within a scalar; the scanner previously folded it into the value. The marker must begin a line and be followed by a boundary to be rejected, so inline dashes ("a --- b"), a --- with no following boundary (---b), and an indented --- remain ordinary content. Lifts official test-suite parse-level conformance from 268/333 (80.5%) to 270/333 (81.1%), with no regression.
• A block sequence can no longer start on the same line as its anchor or tag (&a - x). A block collection must begin on the line after its node properties, so an anchor or tag immediately before the first block entry is now rejected. An anchor or tag on its own line above the sequence, inside a sequence item (- &a x), before a flow sequence (&a [x]), or on a scalar is unaffected. Lifts official test-suite parse-level conformance from 267/333 (80.2%) to 268/333 (80.5%), with no regression.
• An alias node can no longer carry an anchor or tag. An alias is a bare reference, so &b *a (an anchor on an alias) and a tag on an alias are now rejected; the parser previously dropped the property and accepted the document. A bare alias and an anchor or tag on a real node are unaffected. Lifts official test-suite parse-level conformance from 266/333 (79.9%) to 267/333 (80.2%), with no regression.
• A comment can no longer interrupt a multi-line plain scalar. A comment terminates a plain scalar, so content that tries to continue it on a following line (key: word1 then a # line then word2, or a then b # ... then c) is now rejected instead of being silently merged back into the value. A genuine multi-line plain scalar and a trailing comment after a value are unaffected. The parser path that re-merged the scanner-split scalar is removed, since the scanner only splits a plain scalar this way when a comment broke its folding. Lifts official test-suite parse-level conformance from 264/333 (79.3%) to 266/333 (79.9%), with no regression.
• A quoted scalar that spans a line break can no longer be a block implicit key ("c⏎ d": 1). An implicit key in block context must lie on a single line, so a quoted scalar whose open and close quotes sit on different lines is now rejected when used as such a key. The rule is block-only: a flow mapping key may span lines ({ "a⏎ b": 1 }), and a multiline quoted value, a single-line quoted key, and an explicit key (? "a⏎ b") are all unaffected. Lifts official test-suite parse-level conformance from 261/333 (78.4%) to 264/333 (79.3%), with no regression.
• A block sequence can no longer be an implicit key's value on the same line as its : (key: - a); the value must begin on a following line, or use flow style (key: [a]). Like the inline nested mapping rule, this is specific to an implicit key: an explicit- or null-key : opens its line, so a compact sequence after it stays valid, as do a sequence on the next line, a nested sequence (- - a), a flow sequence, and a negative number (key: -1). Lifts official test-suite parse-level conformance from 260/333 (78.1%) to 261/333 (78.4%), with no regression.
• An inline nested block mapping is now rejected. Block style allows only one mapping pair per line, so a scalar followed by : after a block-level value on the same line (a: b: c, a: 'b': c, x: { y: z }in: valid, or trailing content after a quoted value) no longer parses as a nested mapping. The scanner suppresses the implicit key it would otherwise synthesize once the line already holds a pair. A value indicator that opens its line is an explicit- or null-key indicator, whose value may legitimately be a compact mapping (? k then : a: 1), so that, flow mappings ({a: b, c: d}), next-line nesting, and colons inside scalars are unaffected. Lifts official test-suite parse-level conformance from 256/333 (76.9%) to 260/333 (78.1%), with no regression.
• A ... document-end marker no longer accepts content on its own line. Only a comment or blank may follow the marker, so ... invalid is now rejected; the scanner previously skipped the rest of the line. A bare ..., a trailing comment (... # done), and a ... not followed by a boundary (...junk, which is an ordinary plain scalar, not a marker) are unaffected. Lifts official test-suite parse-level conformance from 255/333 (76.6%) to 256/333 (76.9%), with no regression.
• A directive must now be followed by an explicit --- document start. A stream that ends, or reaches a ... document-end marker, while a directive is still awaiting its document (%YAML 1.2 alone, or %YAML 1.2 then ...) is now rejected, as the YAML grammar requires a directive to head an explicit document. This applies to any directive, including an unrecognized one, which is still otherwise ignored. A directive followed by --- (with content, inline, or empty) is unaffected. Lifts official test-suite parse-level conformance from 253/333 (76.0%) to 255/333 (76.6%), with no regression.
• The %YAML directive is now validated. It takes exactly one parameter, the version, optionally followed by a comment, and at most one may appear per document; an extra parameter (%YAML 1.2 foo) or a second %YAML directive is now rejected. Previously any tokens after the version were ignored and duplicate directives were accepted. A well-formed directive, with or without a trailing comment, is unaffected. Lifts official test-suite parse-level conformance from 251/333 (75.4%) to 253/333 (76.0%), with no regression.
• A flow collection no longer accepts an empty entry. A comma separates entries, so one must precede it; a leading comma ([ , a ]), a repeated comma ([ a, , b ]), or the same in a flow mapping is now rejected, while a single trailing comma ([ a, b, ]) and empty collections ([], {}) stay valid. The parser previously skipped a comma without checking that an entry came before it. Lifts official test-suite parse-level conformance from 249/333 (74.8%) to 251/333 (75.4%), with no regression.
• Double-quoted escape sequences now follow the full YAML 1.2 escape table. Previously the decoder recognized only a subset (\" \\ \/ \b \f \n \r \t \u) and silently passed any other character through, so invalid escapes such as \. and \' were accepted while valid ones such as \x, \v, \e, \0, \N, \_, \L, \P, \U, and backslash-space were mangled (\x0d became the text x0d). The decoder now maps every defined escape to its character, handles \x (8-bit) and \U (32-bit) hex escapes alongside \u, treats a backslash before a line break as an escaped line break that joins the lines with no separator, and rejects an unknown or truncated escape. Lifts official test-suite parse-level conformance from 247/333 (74.2%) to 249/333 (74.8%) and value-level from 166 to 170 of comparable cases (90.4%), with no regression.
• A # glued to earlier content on its line (e.g. "value"# c, [ a, b ]#c, >#c) is now rejected: the spec requires a comment to be preceded by whitespace or to open a line, and such input was previously accepted as a comment. A # that opens a line, follows a space, or sits inside a plain scalar (a#b, where it is literal content) is unaffected. The check tracks whether real content has been scanned on the current line, rather than comparing token line numbers, because the streaming tokenizer drains its buffer and a block scalar's blank line emits an empty scalar attributed to the next line. Lifts official test-suite parse-level conformance from 243/333 (73.0%) to 247/333 (74.2%); four wrongly-accepted invalid documents are now correctly rejected with no valid document regressing.
• A block scalar followed by a less-indented comment line no longer fails with a spurious "unexpected indentation". When a comment ends a block scalar, its own column was processed as a dedent and, landing on a width no indentation level held, raised an error; a comment's indentation is now left out of block structure. Relatedly, a whitespace-only line indented past a block scalar's content level now keeps its surplus spaces as content instead of collapsing to empty, so such a line contributes the correct value. Lifts official test-suite parse-level conformance from 240/333 (72.1%) to 243/333 (73.0%) and value-level matches.
• A quoted mapping key may now have a space before its : ("key" : value). A plain key consumes the space before the colon into the scalar, but a quoted key stops at its closing quote, leaving the space, and the implicit-key check looked only at the immediate next character. It now looks past spaces for the colon, as the spec allows. Quoted keys with no space, quoted values, and plain keys are unaffected. Lifts official test-suite parse-level conformance from 238/333 (71.5%) to 240/333 (72.1%).
• A block mapping pair after the first may now carry an anchor or tag on its key (k: 1 / &b key2: 2). The first pair's key properties were consumed when the mapping was entered, but later pairs were not, so an anchored key past the first failed with "expected mapping key". The pair parser now consumes leading key properties for every pair, and the mapping continues across an anchor or tag that begins a key. Lifts official test-suite parse-level conformance from 235/333 (70.6%) to 238/333 (71.5%).
• An explicit mapping key (? key) with no following : now maps to null instead of failing to parse, so several ? key entries in a row (a set, for instance) each map to null. The parser required a : after every explicit key; it now treats a missing one as an implicit null value. Explicit keys with values, and complex keys generally, are unaffected. Lifts official test-suite parse-level conformance from 229/333 (68.8%) to 235/333 (70.6%).
• An unrecognized directive (e.g. %FOO) before a document is now ignored, as the YAML spec requires (a warning, otherwise no effect), instead of being rejected with an error. %YAML and %TAG are unchanged, and a directive after content (where one cannot appear) is still rejected. Lifts official test-suite parse-level conformance from 227/333 (68.2%) to 229/333 (68.8%).
• A plain scalar at the document root now folds across lines that sit at column 1, so a bare multi-line value such as a / b / c becomes "a b c" instead of failing to parse. The continuation check required a continuation to be more indented than the scalar, but a root scalar has nothing enclosing it, so its enclosing-block indent is -1 and a continuation may start at column 1. The continuation now stops at a document marker (--- / ...), so a scalar never folds across a document boundary. Lifts official test-suite parse-level conformance from 221/333 (66.4%) to 227/333 (68.2%). (A stream test that asserted two bare plain lines were rejected as extra content was corrected: that input is a valid multi-line scalar; genuine extra content, like a flow node followed by a scalar, is still rejected.)
• A multi-line single-quoted scalar now folds its line breaks, like the double-quoted fix below; both share the same flow line folding, so the fold logic is now one helper. Lifts official test-suite value-level conformance from 143/169 (84.6%) to 147/169 (87.0%), with no regression.
• A multi-line double-quoted scalar now folds its line breaks instead of keeping them raw. The decoder appended real line breaks and continuation-line indentation verbatim, so "a\n b" came back as "a\n b" rather than "a b". It now applies flow folding: a single break folds to a space, a blank line to one newline, and whitespace adjacent to a break (a line's trailing, the next line's leading) is stripped, while first-line leading and last-line trailing whitespace and \n escapes are preserved. Lifts official test-suite value-level conformance from 135/169 (79.9%) to 143/169 (84.6%), with no regression; parse-level is unchanged because these documents already parsed, just to the wrong tree.
• A root node that begins on the document-marker line (--- >, --- |, --- foo, --- {a: 1}) is no longer discarded. The marker scanner skipped the rest of the --- line unconditionally, so a block-scalar header was dropped and its body was mis-read as a plain scalar (folded to spaces, no trailing newline) and a same-line plain or flow node was lost entirely. The document start now keeps any real same-line content for the parser, skipping only trailing spaces or a comment. Lifts official test-suite value-level conformance from 130/170 (76.5%) to 135/169 (79.9%), with no regression; parse-level is unchanged because these documents already parsed, just to the wrong tree, which only the value-level metric could see.
• A multi-line plain scalar whose value begins on its own line under a mapping key now folds its continuation lines instead of stopping after the first. The continuation check compared the next line's indent against the value's own pushed indent, so a continuation at the same indent failed the strict >; it now compares against the parent block's indent, matching the spec (continuation must exceed the mapping's indentation, not the value's). Lifts official test-suite parse-level conformance from 211/333 (63.4%) to 221/333 (66.4%), with no regression across the existing suite.

Changed

• Split multi-type source files so each file declares exactly one top-level type (docs/rules/code-style.md): the Tagged node component types, the validation report types, TokenKind, and the event-stream composer helpers each move to their own file. Public type names are unchanged. scripts/check-namespacing.sh is now namespace-aware and detects multiple sibling types declared inside extension blocks, which the previous column-anchored scan missed.
• Merge-key (<<) override resolution now lives in a single internal helper, Parsing.MergeResolution, shared by the buffered and streaming event composers. Both paths previously carried an identical copy of the inherited-versus-local pair merge, so the subtle precedence rules (local keys win, earlier sources win, inherited-then-local ordering) now have one source of truth. No behavior change.

Removed

• Remove three Parsing.ParseError cases that were never thrown: emptyDocument (empty and comment-only documents parse to null), expectedMappingKey (superseded by unexpectedToken carrying an "expected mapping key" message), and tabIndentation (tabs in indentation are reported by the validation layer's PreflightScanner, not the parser). No reachable behavior changes.

Fixed

• Preserve blank lines in block scalars. The scanner dropped every blank line within and after a block scalar, so a literal | lost its internal blank lines, a folded > turned a blank line into a space instead of a newline, and the |+ / >+ keep indicator could not preserve trailing blank lines. Blank lines are now captured as empty content in both the batch and streaming scan paths (which had duplicated the loop), and blockScalarValue applies literal versus folded line semantics and clip/strip/keep chomping correctly. A block scalar without blank lines is unchanged.
• Keep a more-indented line inside a folded > block literal, with its line breaks preserved, rather than folding it into the surrounding text.
• Preserve leading blank lines between a block scalar header and its first content line. They precede the indent token, so they are buffered and emitted as empty content once the content indentation is established.

Documentation

• Correct SECURITY.md: fix the reporting contact address and replace the scope section, which described an unrelated static-site generator, with the YAML parsing, validation, and emitting surface that is actually in scope.

[0.1.5] - 2026-06-23

Documentation

• Document why maxNestingDepth is the necessary and sufficient safety bound for deeply nested input: a Model.Value is a recursive tree whose every operation (compose, emit, compare, hash, and especially deallocate) recurses with nesting, and Swift cannot deallocate a recursive value type iteratively, so bounding the tree's depth at parse time is the only complete protection. Records the measured headroom, why the bound cannot be raised without an iterative parser (and would be pointless past the ~5,000 deinit limit), and the caveat that trees built by encoding a deep Codable value bypass it.

[0.1.4] - 2026-06-23

Fixed

• Reject documents nested beyond a fixed depth (maxNestingDepth) with a nestingTooDeep parse error instead of overflowing the recursive-descent parser's stack. A pathologically nested input (for example hundreds of nested [[[...]]] or deeply indented mappings) previously crashed the process; it now fails cleanly. The limit is well above the nesting of real-world specs, which are unaffected.

[0.1.3] - 2026-06-23

Fixed

• Parse a leading # in block scalar content (>, >-, |, |-) as literal text instead of a comment. A block scalar whose first content line began with #, such as an OpenAPI $ref: >- folded onto #/components/..., was previously dropped to an empty string.

[0.1.2] - 2026-06-06

Added

• Document the real-world YAML corpus, fuzz/property gate, and CI artifact contract for production hardening.
• Add machine-readable parser diagnostic codes to validation report payloads and cover malformed production-shaped YAML with 10+ structured diagnostics.
• Vendor a 114-file real-world YAML corpus with a machine-readable manifest, default metadata checks, and an opt-in full parse/validate/round-trip gate.
• Add large public APIs.guru Stripe and Zoom OpenAPI YAML specs to the opt-in corpus gate.
• Add a reduced synthetic ACME Zephyr fixture set for Stitcher-style multi-file OpenAPI inputs and bundled output.
• Add a full renamed Birch-style ACME fixture catalog with 594 YAML files, preserving module/file structure while replacing private organization names, domains, and documentation URLs.
• Add YAML 1.2 JSON-subset compatibility for compact flow mappings such as {"openapi":"3.0.0"}, including regression coverage for colons inside flow mapping values.
• Add JSON compatibility tests and artifacts that compare PureYAML against Swift's JSON decoder across JSON roots, escapes, Unicode surrogate pairs, exponent numbers, nested values, and whitespace.
• Preserve round-trip fidelity for mapping keys that require quotes, including trailing-space keys found in the large Zoom OpenAPI corpus seed.
• Add an opt-in Yams differential script that compares parse behavior for the checked-in real corpus without adding Yams to the PureYAML package manifest.
• Add an opt-in Yams diagnostic comparison script that records PureYAML structured malformed-input diagnostics alongside Yams parser errors.
• Add an opt-in Yams validation comparison script proving structured duplicate key validation on YAML that both parsers can load.
• Add an opt-in Yams throughput script and scheduled/manual CI artifact for release-mode parser performance comparison on representative corpus seeds.
• Add an opt-in PureYAML phase profiler that times scanner, event parser, composer, lazy parse, validation, and dumping phases on slow corpus seeds.
• Compose normal parser output from events as they are emitted, avoiding a full intermediate event array while keeping parseEvents available for explicit event materialization.
• Lazily scan tokens for normal parse and parseStream calls, avoiding a retained full token array on the main parser path.
• Track reader positions with a UTF-8 cursor so ASCII-heavy scanner advancement avoids per-character string allocation while preserving byte-accurate marks.
• Add deterministic generated corpus properties for valid YAML round trips and malformed real-seed mutations with structured diagnostics.
• Write corpus run artifacts under .build/pureyaml-artifacts/, including real seed summaries, generated mutation summaries, seed metadata, and environment details.
• Add a scheduled/manual CI corpus job that runs the corpus and Yams differential gates and uploads the generated artifact bundle.

[0.1.1] - 2026-06-06

Added

• Add platform CI badges and an active production-hardening roadmap to the README.

Changed

• Add release-mode build and test gates to the macOS, Linux, Windows, and WASM verification scripts.
• Update GitHub Actions checkout steps to actions/checkout@v6 so CI uses the current Node 24 action runtime.

Fixed

• Treat more-indented plain scalar continuation lines that start with - as text unless they appear at a known sequence-entry indentation. This fixes OpenAPI-style allOf descriptions while preserving nested block sequences such as - - 123.
• Parse explicit scalar keys whose : value starts a same-line mapping and continues with indented mapping siblings, matching large OpenAPI schema keys.

[0.1.0] - 2026-06-05

Added

• Bootstrap PureYAML as a root Swift package with one PureYAML library product, no external SwiftPM dependencies, no C sources, no generated parser targets, and no Foundation requirement in the library target.
• Add the core pure-Swift YAML model with ordered mappings, sequences, scalars, duplicate-key preservation, and first-class complex mapping keys through Model.Pair.keyNode.
• Add parser support for block mappings, block sequences, comments, flow collections, quoted strings, literal and folded block scalars, anchors, aliases, YAML directives, document markers, merge keys, complex mapping keys, multi-document streams, and selected explicit built-in scalar tags.
• Add deterministic YAML dumping with block output by default, optional flow collections, conservative plain scalars, conservative literal block scalars, complex mapping key dumping, and multi-document stream dumping.
• Add tag-preserving parsing with PureYAML.parseTagged(_:) and PureYAML.parseTaggedStream(_:), plus tagged validation rules for unsupported built-in tags and tags applied to the wrong node kind.
• Add PureYAML.Tagged.Constructor for caller-owned tagged construction with exact missing-handler and kind-mismatch errors, recursive path context, and a model-value fallback that preserves mapping order and duplicate keys.
• Add path-aware validation with duplicate-key checks, custom rules, rule predicates, strict and non-strict behavior, warning collection, stream document indexes, deterministic validation paths, and direct value-tree validation for states ordinary loaders may collapse.
• Add diagnostic-first validation reports, raw-source preflight scanning, Validation.ReportError, and Markdown, YAML, and JSON report rendering for application-owned files or error bodies.
• Add scalar, keyed, unkeyed, nested, dynamic-key, dictionary-like, and super-coder Codable conversion APIs with exact path-aware errors.
• Add fixture-backed compatibility coverage for scalar spellings, explicit tags, collections, anchors, unsupported YAML gaps, literal block emission, downstream documents, and deliberately failing validation fixtures.
• Add a real-world YAML fixture corpus with representative short, medium, large, and very large documents, including OpenAPI, Kubernetes, GitHub Actions, Docker Compose, Prometheus, and cert-manager YAML.
• Add macOS, Linux, Windows, and WASM verification gates, hosted CI, a full local verification script, a pre-push hook, usage documentation, migration boundaries, attribution, and release notes.

Changed

• Lower the package tools version to Swift 6.1 for hosted macOS CI compatibility.
• Harden duplicate-key validation to use set membership while preserving exact diagnostics.
• Make validation rules immutable after construction.
• Preserve keyed super-encoder field order even when delayed child encoders are written in a different order than they were requested.
• Make keyed default superEncoder() and superDecoder() use the standard super mapping key instead of the current mapping.
• Resolve Yams-compatible plain scalar spellings for yes and no booleans, radix-prefixed integers, numeric separators, and .inf and .nan floats.
• Broaden opt-in literal block emission while preserving exact parser round-trips for every emitted block scalar.
• Harden block mapping, multiline plain-scalar parsing, merge expansion, tagged parsing, lower-column mapping siblings, indented root fragments, JSON-style flow mapping pairs, tab-indented corpus files, and empty collection emission.