adf-codec/docs/decisions.md

Decisions

Plain markdown is a flavour of the grammar

2026-09-27, the maintainer. Goal 2. Valid while the plain flavour's spellings are ones the markdown grammar can read and write.

The lossy pair is the plain flavour: the markdown grammar's reader and writer with the flavour set, its spellings — alerts, callouts, task markers, == — read and written there, so a marker line and a backslash reach them intact; what the flavour cannot spell reduces ADF→ADF ahead of the writer.

The round-trip is the product

2026-08-23, the maintainer. Goal 1. Valid while a consumer saves back through the lossless pair.

markdownToAdf(adfToMarkdown(doc)) and htmlToAdf(adfToHtml(doc)) must equal doc — anything less silently destroys content an editor could not represent, in a document it did not author. When losslessness and readability conflict, losslessness wins. Round-trip equality is a property tested over a corpus, not a claim made in prose.

Markdown in is a canonical fixpoint

2026-08-23, the maintainer. Goals 1 and 3. Valid while markdown input may be written by hand.

The other direction is a canonical fixpoint, not byte-identity: human markdown normalizes, the way back yields the library's canonical spelling, and that spelling round-trips byte-identically — where there is a way back. CommonMark spells some things the flavour has no escape for — a paragraph opening with a code span whose backticks read back as a fence — so a parse succeeding does not imply a spellable document; corpus/commonmark-spec/exceptions.json names those.

Equality is editor-normal

2026-08-24, the maintainer. Goal 1. Valid while markdown cannot tell apart the ADF shapes this merges.

"Equals" is structural equality over editor-normal ADF — adjacent text nodes with identical marks and no attributes merged, JSON number semantics, an empty attrs object, marks array or content array the absent key — the only domain markdown can restore.

Unknown nodes ride the carry

2026-08-23, extended to misplaced known nodes 2026-08-26, the maintainer. Goal 1. Valid while ADF holds nodes, or node positions, this library does not spell.

An unknown ADF node is carried opaquely — raw JSON rides a dedicated syntax in both formats and restores to a deep-equal node. The round-trip holds for documents newer than the library. So does a known node no section spells where it stands: a markdown serializer spells a node by type without checking its position, and refusing loses a document ADF itself keeps in an unsupportedBlock. Where a container's own spelling cannot hold the child it has — a bulletList outside listItem, a codeBlock outside text — the error result names that instead.

Foreign HTML is refused by name

2026-08-23, the maintainer. Goals 1 and 6. Valid until the HTML dialect's element set lands (todo.md, 6).

An unmappable foreign HTML element is an error result naming the element — never a silent drop.

Names stay text

2026-08-23, the maintainer. Goal 7. Valid while resolving a name to an id needs I/O.

A bare @name or :smile: in typed text stays a text node. Only directives produce mention/emoji/media nodes; resolving names to ids is the consumer's job.

Directives under !adf:

2026-08-23, prefixed !adf: 2026-09-16, the maintainer. Goals 3 and 4. Valid while prose does not write !adf:.

Directives are one grammar for everything markdown lacks, namespaced under !adf:: !adf:panel info … !adf:/panel blocks, !adf:mention[@Mikael]{id=5b10a2} inline, \!adf: the one escape. Not CommonMark's generic-directives proposal: its ::: claims a form prose writes, and its fence-length discipline ties a container's opener to its own body, where closing from the opener nests by itself and leaf versus container falls out of the node's content model.

CommonMark is a subset

2026-08-23, the maintainer. Goal 3. Valid while prose rarely writes the shapes the carve-outs claim.

Plain CommonMark is a subset, with carve-outs (spec/flavour.md): literal text shaped like a directive, a pipe table or a ~~ pair is claimed — plus one image gap.

Tables

2026-08-23, the maintainer. Goal 4. Valid while a pipe table holds only one header row and inline cells.

One header row plus plain inline cells → pipe table; anything richer → directive form.

Links

2026-09-13, nesting 2026-09-17, the maintainer. Goals 1 and 4. Valid while CommonMark's link syntax is what readers edit.

[text](url "title"), or <url> for a bare autolink-shaped text, wherever CommonMark spells the mark; !adf:link[text]{attrs} where it does not — an attribute CommonMark cannot hold, an href or title no canonical escape spells, a paragraph opening whose CommonMark spelling would read as a link reference definition — and a directive link CommonMark could spell is refused. No link wraps a link — the bracket form goes literal, the directive form refused — which is CommonMark's prose where its reference implementation nests one <a> in another.

Ids stay site-local

2026-08-23, the maintainer. Goal 1. Valid while ADF ids are minted per site.

Identity-bearing nodes carry their ids in attributes; a document is only portable within its site — accepted.

The HTML dialect

2026-08-23, the maintainer. Goals 4 and 7. Valid while HTML output is read by consumers styling it themselves.

The HTML dialect mirrors the markdown flavour: semantic elements, stable adf-* classes, data-* for what HTML cannot express, text always escaped. No stylesheet ships.

No runtime dependencies

2026-08-23, the maintainer. Goal 7. Valid while ~20 lines of own code, or a vendored table, do each job a dependency would.

dependencies is empty. A runtime dependency enters only through an entry here stating why ~20 lines of own code cannot do the job, who maintains it, and what auditing it costs. So the CommonMark and HTML parsers are written in this repo.

Standards ship as data

2026-08-30, the CommonMark suite 2026-09-05 and ADF's schemas 2026-09-13, the maintainer. Goals 1, 3 and 7. Valid while each table is fixed data a dependency would only wrap.

A table a standard fixes is data rather than a dependency: HTML5's 2125 semicolon-terminated character references ship packed in their own module, so entity decoding is complete without one. The CommonMark spec suite is the same shape of data and ships vendored at corpus/commonmark-spec/ rather than as the commonmark-spec dev dependency — that package is CommonJS-only, and Renovate auto-bumping a spec version would silently point the vendored exception list's example numbers at a renumbered suite. A spec bump is a deliberate re-pin, exceptions re-derived by hand beside it. Atlassian's ADF JSON Schemas ship vendored the same way, at spec/adf-schema/, rather than as the @atlaskit/adf-schema dev dependency — CommonJS-only, some fifty packages with React among them, and a release most days for Renovate to automerge — re-pinned by hand when a payload or a report shows the need.

fast-check

2026-09-14, the maintainer. Goal 1. Valid while a failing generated document needs shrinking by hand otherwise.

fast-check earns its place as a devDependency shrinking a failing generated document to the nodes that break it.

Any ES2022 engine

2026-09-01, the maintainer. Goal 7. Valid while ES2022 is the floor browsers and servers share.

The library runs on any ES2022 engine, not only Node — a browser as readily as a server. The shipped source is ECMAScript and nothing else: no host import, no host global, no DOM. tsconfig.build.json is that gate, typechecking and emitting the shipped files alone, so node:fs, process and an ES2024 method are compile errors here rather than a consumer's crash there. The standard is the line, never an engine list: one implementing it in part — Hermes is the live doubt, on the Unicode property escapes emphasis matching leans on and on lookbehind — is out of scope rather than a bug. Node's test runner, the corpus reads and the build are the repo's own, never the library's, and engines.node states the floor the shipped JavaScript needs — >=18 — never the higher one those repo-only tools want.

ESM only

2026-08-23, the maintainer. Goal 7. Valid while the audience's toolchains all import ES modules.

No CommonJS build, no dual-package hazard.

One built entrypoint

2026-08-23, the maintainer. Goal 7. Valid while Node refuses to type-strip under node_modules.

Built JavaScript, .d.ts beside it. Do not add a TypeScript-source entrypoint — Node refuses to type-strip under node_modules (ERR_UNSUPPORTED_NODE_MODULES_TYPE_STRIPPING), so it cannot serve an npm consumer.

Public on npm

2026-08-23, the maintainer. Goal 7. Valid while the package's source stays public beside it.

Published to public npm as @larvit/adf-codec. Public source: the Gitea repo goes public, LICENSE in place, before the first publish.

The formats are API

2026-08-23, content models 2026-09-16, the maintainer. Goals 1 and 6. Valid while consumers store what the library emits.

The emitted markdown and HTML are contracts. After 1.0: previously-emitted output parsing differently, or not at all, is MAJOR; new syntax while old output still round-trips is MINOR. Pre-1.0, normal 0.x rules. A spelled node's content model is part of that contract — leaf or container is the model, not the syntax — so giving a spelled node's model content it had not, or taking it away, is MAJOR whatever ADF's own schema does.

The error surface is a contract too; README.md §The errors states it to the consumer, and the types in src/result.ts hold its shape.

The code list

2026-08-25, the maintainer; dated below where a rule came later. Goal 6. Valid while a consumer switches on code with no default.

• Adding, removing or renaming a code is breaking, so a new cause takes an existing code whose name reads true of it in both directions; where none does and a plain name exists, a new code — in any 0.x minor, and after 1.0 only in a MAJOR (2026-09-18).
• A refusal whose cause is this library's own invariant rather than the input takes the existing code nearest what the consumer sees — a document that does not convert is unsupported-node-shape — since a code no input reaches is one no consumer can switch on (2026-09-20).
• A refusal no spelling recovers from is a gap in the flavour rather than a code: give the flavour the spelling and the code goes (unspellable-link, 2026-09-13). A cause the carry answers gets no code: a mark no spelling writes rides the carry with its node.

Which code a cause takes

2026-08-28, the maintainer; dated below where a rule came later. Goal 6. Valid while a consumer handles one cause alike whichever node, attribute or direction raised it.

• A code names the cause; where one cause recurs across node types, across one mark's attributes or across directions, one code covers them all and path and message say which — unsupported-nesting-depth is the 500-level guard whichever direction hits it, unspellable-character the text node and the code block alike. Where two codes stay apart, the line between them is what they name: unspellable-character is a character CommonMark rewrites wherever text holds it, unspellable-whitespace the newline no inline directive's content slot spans, in either direction.
• A claim code names the spelling claimed, never the node that spelling would have built: a malformed !adf:table is a malformed-directive, and an alignment colon a malformed-pipe-table — the flavour's own delimiter row is - runs, so the grammar refuses the colon rather than ADF's missing column model doing it. What the grammar itself refuses stays a claim code, key order among it, and a leaf given a body is refused at its opener, as a container missing its closer is (2026-09-16).
• A directive whose name reads back to no node is unknown-directive-name rather than a claim code — the spelling is well formed, and telling that apart from a typo is what a consumer switches on when a later MINOR gives the name meaning. A reserved name is a known name, so never that code, and the two the flavour reserves part on form: a form the grammar does not have is a claim code — !adf:carry, whose carry is the fence — and a well-formed form in the wrong place is unsupported-node-shape, !adf:listBreak parting anything but two adjacent lists of one type (2026-09-01).
• A well-formed directive the node tables refuse — an attribute a node does not hold or spells elsewhere, a value outside its kind or its canonical spelling, an argument, or a body of a shape its content model does not take — is unsupported-node-shape, the emitter's code for the same mismatch read the other way: one code across both directions for good, since the call site knows which direction it called and parting them after 0.1.0 is MAJOR (2026-09-23).
• A non-finite number takes two codes: unsupported-node-shape parsing, not-an-adf-document emitting — no document holds one, so no round-trip crosses them (2026-09-23).

message and path

2026-09-03, the path 2026-09-23, the maintainer. Goals 3 and 6. Valid while a person fixing the input reads message.

• A message names the violation, not the rule alone — a rule by itself states a truth the reader must invert before it reads as a failure — and where the flavour's claim refuses ordinary prose it names the escape that unclaims the form claimed: \!adf: for a directive, block line and inline alike, \| for every pipe row.
• not-an-adf-document carries the document's own path throughout: seven of the guard's eight branches read the document's own shape, and threading a path to the eighth — a malformed node anywhere in the tree — wants the manual stack the no-recursion rule (AGENTS.md §11) forces, whose empty half no input reaches. The message names the violation instead.

Publish on a version bump

2026-08-23, converging 2026-09-03, the maintainer. Goal 7. Valid while CI on main holds the npm token.

package.json version on main is the source of truth. CI on main: tests green and the version not yet on npm → publish and tag vX.Y.Z. No bump, no deploy. publish.sh is that job.

The publish and the tag each check their own end state — the version on npm, the tag on the remote — so a run that dies between them converges on the next push to main rather than leaving npm ahead of the tags. An unanswered registry reads the same as an unpublished version, which npm's own duplicate rejection is what catches. The job rebuilds rather than taking the gate's dist: the lockfile is committed, the image is patch-pinned and tsc is deterministic, so the two builds agree, and promoting an artifact would make the release path depend on a store that the gate would then have to keep.

Docs describe the release being built

2026-09-16, the maintainer. Goal 7. Valid while a bump on main publishes.

Docs on main describe the release being built rather than the version npm holds, so they match it the moment the bump publishes; add no interim note marking the gap.

No schema validation

2026-08-23, the mark refusal 2026-08-25, the maintainer. Goal 1. Valid while the site a document is saved to validates it.

No ADF schema validation or exported validator. A refusal that keeps the round-trip is not schema validation, so the one a spelled node carrying the same mark type twice earns stays, and input nesting a spelling inside its own kind (*(*a*)*) names that mark once.

No streaming APIs

2026-08-23, the maintainer. Goal 8. Valid while a document fits in memory.

A call takes a whole document and returns a whole result.

No performance budget

2026-08-23, the maintainer. Goal 8. Valid while no persona needs a speed figure.

Nothing is tuned past the scanning rule (AGENTS.md §11), and no figure is promised.