adf-codec/AGENTS.md

# Working in this repo

Decisions a reader would otherwise relitigate, and the rules for every collaborator, human or
agent. Using the library: `README.md`. What is still to build: `todo.md`.

## 1. Three formats, ADF is the hub

ADF, one markdown flavour, one HTML dialect. Six directions exposed, but markdown↔HTML compose
through ADF: four conversions exist to keep correct — never write a fifth. No fourth format, ever;
each one doubles the directions.

## 2. The round-trip is the product

`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.

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.

"Equals" is structural equality over editor-normal ADF — adjacent text nodes with identical marks
merged, JSON number semantics, an empty attrs object, marks array or content array the absent
key — the only domain markdown can restore.

Round-trip equality is a property tested over a corpus, not a claim made in prose.

## 3. Unknown input policy

- Unknown ADF node: 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.
- Unmappable foreign HTML element: error result naming the element — never a silent drop.
- Bare `@name` / `:smile:` in typed text: stays a text node. Only directives produce
  mention/emoji/media nodes; resolving names to ids needs I/O, which is the consumer's job.

## 4. The flavour

- Directives, one grammar for everything markdown lacks: `:::panel info` … `:::` blocks,
  `:mention[@Mikael]{id=5b10a2}` inline. Prior art: CommonMark's generic-directives proposal.
- 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: one header row plus plain inline cells → pipe table; anything richer → directive form.
- Identity-bearing nodes carry their ids in attributes; a document is only portable within its
  site — accepted.
- The HTML dialect mirrors this: semantic elements, stable `adf-*` classes, `data-*` for what HTML
  cannot express, text always escaped. No stylesheet ships.

## 5. Dependencies

`dependencies` is empty. A runtime dependency enters only through a decision 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. 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. `devDependencies`: few, each earning its keep;
they never reach a consumer.

## 6. The package contract

- 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 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 §10's property escapes
  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 — no CommonJS build, no dual-package hazard.
- One entrypoint: 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.
- Published to public npmjs as `@larvit/adf-codec`. Public source: the Gitea repo
  goes public, LICENSE in place, before the first publish.
- Exact versions: `save-exact=true` in `.npmrc`.

## 7. Nothing about any consumer

No Jira client, no HTTP, no REST shapes, no issue keys, no actual consumer named anywhere. Design
against the README's personas.

## 8. Semver: the formats are API

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.

The error surface is a contract too. `ConvertError` is `{ code, message, path }` — the code from a
closed list a consumer may switch exhaustively, the message free text, the path the node's position
from the document root. Adding, removing or renaming a code is breaking, so a milestone meeting a
new failure cause reuses a code where one fits; the list is complete at `0.1.0`. A code names the
cause; where one cause recurs across node types 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. A claim code names the spelling claimed, never the node that spelling would have built:
a malformed `:::table` is a `malformed-directive`. A cause the carry answers gets no code: a mark no
spelling writes rides the carry with its node. 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. What
the grammar itself refuses stays a claim code, key order among it; 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 its content model does not take — is
`unsupported-node-shape`, the emitter's code for the same mismatch read the other way. A
refusal found before its position is known — the block walk's, a directive reader's — is a
`ConvertFault`, the code and message without the path; the node walk attaches the path as it
descends, so a document reports its first error in document order.

## 9. Release automation

- `package.json` version on `main` is the source of truth. CI on `main`: tests green and version
  differs from npm → publish and tag `vX.Y.Z`. No bump, no deploy; the bump is each shipping PR's
  deliberate semver judgment.
- Renovate watches devDependencies, Docker pins and action tags; automerges everything on green CI.
- Docker images pin the full patch version (`node:24.19.0-alpine3.24`, never `node:24`), as
  specific as the publisher tags: `oven/bun:1.4.0-alpine` pins Bun's patch and leaves the base
  floating because Bun publishes nothing narrower. Actions pin semver tags.

## 10. Tests first, in Docker

Test for the behaviour wanted first, then implement until green. `node --test`, beside the code.
Node, tsc and npm never run on the host — only via the pinned images (§9). Tests are independent,
coverage does not decline, containers are torn down after a run.

The gate runs that same suite under Deno and Bun as well as Node, the three images pinned alike,
and neither extra leg is Node's proof twice. Deno refuses an extensionless or directory specifier,
so it holds the module graph to the fully-spelled form a browser can load; Bun runs
JavaScriptCore, the one engine of the three that is not V8, where the Unicode property escapes
emphasis matching leans on can disagree. Both refuse a run matching no test, so Node's is the only
vacuous-green guard, and a test may reach only for what all three `node:` shims carry — the price
of proving those engines over the corpus rather than over a smoke import.

The floors live in the `test` script, so `npm test` and the gate are one path: 100% of lines and
functions, and a branch floor that only ever moves upward. It sits below 100 because the guards
`noUncheckedIndexedAccess` and ADF's optional keys force — `?? []`, `?? {}`, `?.`, an index
compared against `undefined` — have a half no valid document reaches.

The corpus, all checked in: hand-built fixtures per node and combination; real sanitized ADF from
live Atlassian APIs; property-generated ADF trees; the CommonMark spec suite against
`markdownToAdf` and `markdownToHtml`.

`spec/flavour.md` is read as a source too, so the node tables cannot drift from the prose they
copy: each `- ` bullet in `## Block nodes`, `## Inline nodes` and `## Marks` declares the nodes
named before its first em dash, with the attributes following `Attributes: ` — a parenthesized
value set reading `string` — and must equal the tables in `adf/`. Keep prose in those sections out
of a bullet; fenced examples are skipped. It guards the attributes alone: nodes that differ in
content model share a bullet, and the argument attribute is spelled ahead of `Attributes: `, so
both answer to the round-trip corpus and to nothing else where a node has no fixture.

## 11. Code rules

- Two-space indent, strict TypeScript, English everywhere. Alphabetical order wherever order
  carries no meaning.
- Failures are values: everything returns
  `Result<T>` — `{ ok: true; value } | { ok: false; error: ConvertError }` — nothing throws.
  `try/catch` only wrapped tightly around a call that genuinely throws, converted to a result on
  the spot. A reader with no path to name returns `Read<T>` instead, the same two arms over a
  `ConvertFault`, and `faulted` attaches the path where the walk knows it.
- Only the hard break's inline segment holds a raw newline — every other spelling escapes one or
  refuses it — which is how the whitespace carry finds a line edge.
- Emphasis is spelled against CommonMark's matching, never flanking alone: a delimiter run in text
  escapes wherever CommonMark could open or close with it, leaving the emitter's own delimiters the
  only ones in play, and a pair that matching hands to another delimiter rides the carry instead.
  `matchEmphasis` transcribes the reference `process_emphasis` line for line, and its closer walk and
  opener search stay whole: broken into named steps they drift from the algorithm being faithful is
  the whole point of.
- A readable spelling tried ahead of a general one — a CommonMark block, the image, the pipe
  table, a pipe cell — gives way with `undefined` for every shape it cannot spell, and fails only
  where the general form fails on the same node. Refusing there refuses a document the general
  form spells, so a refusal the general form does not share belongs in the general form or
  nowhere — save the nested list a tight spelling would swallow, whose refusal the
  tight-versus-blank answer owns (`todo.md` 2b).
- Nothing recurses unbounded: the guards walk iteratively, and blocks, marks and JSON values — an
  attribute's and a carried node's alike — are all held to 500 levels, so a deep document is a
  `Result` rather than the stack overflow that waits near 2000.
- A reader takes the text and an index — a sticky regex whose `lastIndex` the caller sets on the
  line before it reads, `indexOf` — never a fresh slice per character, and a per-character walk
  hoists the scan that does not vary with the character. The pipeline persona feeds documents
  nobody typed, and a megabyte through a quadratic walk is a minute rather than a millisecond.
- No casts: `as`, `as unknown as`, non-null `!`. A boundary owes a type guard validating the
  fields it claims (`isAdfDocument`); past it everything is typed. Make invalid states
  unrepresentable.
- `src/adf/` holds ADF's own knowledge and imports no format. Each format directory (`markdown/`,
  `html/`) parts into `emit/` (ADF→format) and `parse/` (format→ADF), its root holding what both
  directions read. A construct's reader lives in that root beside the regex the emitter escapes
  against, so the two cannot drift; a reader with no emit counterpart goes in `parse/`, unless it is
  part of a construct the root already holds — a grammar stays in one file rather than splitting
  across the seam. A rule both
  directions must answer alike — whether a list marker interrupts a paragraph — is one function
  there too, never a copy per direction, however conservative the copy would be. Where the rule is
  the emitter's own choice, input consults it rather than restating it: the parser asks
  `commonMarkSpelling` which form the emitter picks, so no fixture the emitter writes can be
  refused, and a spelling the emitter refuses gives its own error rather than a second name for it.
- The attribute vocabulary is ADF's: `adf/` walks it and narrows each value to its kind, and a
  format spells the narrowed value. A spelling that re-checks the type is the check's second copy.
  Reading a spelling back is the format's own: the reader sits beside the spelling it inverts, so
  decode-respell-compare cannot drift, and each format writes its own — canonical JSON for a
  number is the markdown flavour's choice, not ADF's.
- Explicit over implicit; descriptive names; no catch-all files (`utils`, `helpers`, `misc`); a
  file does not repeat its directory in its name — `adf/document.ts`, never
  `adf/adf-document.ts`.
- Reuse before adding; the smallest sufficient diff is the benchmark; no speculative generality —
  a second consumer, or it goes.

## 12. Prose to a minimum

Applies everywhere: comments, every markdown file in this repo (this one included), PR text.

- Default is no comment. One earns its single line only by naming an invariant, footgun or
  external constraint the code cannot show — never restatement, history, absence or arrangement.
  A second line belongs in the commit message or a decision entry here.
- Every prose comment in a diff is a review question; the default answer is delete.
- A doc paragraph says what the repo cannot say for itself, or it goes. The fix for a redundant
  one is deletion, not trimming. A false claim in any doc is a bug, fixed where found.
- Published text — npm README, error messages, API docs — never references internal systems,
  tickets or repos.

## 13. Commits and PRs

One-line commit messages and PR titles; short PR summaries. No AI-attribution markers, ever.

## 14. Non-goals

No wiki markup (§1), no network or filesystem I/O, no name→id resolution (§3), 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 shipped CSS (§4), no
streaming APIs, no performance budget past §11's scanning rule — nothing here is tuned, and no
figure is promised. A CLI is a later goal (`todo.md`), not a non-goal.

## 15. The working loop

One unchecked `todo.md` item per session, in the smallest PR-able chunk — split a big milestone
into sub-items in `todo.md` before starting it. A chunk running a little over or under that is not
worth deliberating; what matters is that nothing is left undone in the end. Per chunk:

1. Fresh worktree off updated `origin/main`; implement tests-first (§10).
2. Run the larv-review flow until it passes and CI is green. A reviewer launch states the latest
   gate result (commit and outcome); a reviewer does not re-run `ci.sh` or the tests when a
   result exists for the commit under review, or when the diff since that result cannot affect
   it (docs-only) — re-run only what its own findings or fixes invalidate.
3. Merge the PR (standing authorization, this repo only, granted through the `0.1.0` release —
   PR #3), check the box in `todo.md` and move the item's text to `todo-history.md`, leaving its
   title behind, report, stop. The next chunk gets a fresh session.

Ask, don't guess: any choice where what the maintainer would pick is not near-certain gets asked,
and the answer lands as a decision in this file. The confidence bar is very high — asking too
often is the accepted cost, guessing wrong is not.

Reserved for the maintainer, never the agent: changing `version` in `package.json` (a bump on
`main` publishes, §9 — every release including `0.1.0` is the maintainer's), making the repo
public, and creating the `NPM_TOKEN` secret.

A continuous loop session (`/loop`) counts as a chain of sessions: one chunk per iteration, each
iteration starting by re-reading `AGENTS.md` and `todo.md` and trusting them over anything
remembered from earlier iterations. The loop session is a thin driver: each chunk's work runs in
a fresh-context subagent holding this file as its charter, and the driver only relays maintainer
questions, runs the review flow, merges, and cleans up. The loop stops when only
maintainer-reserved acts remain.