README.md

@@ -3,7 +3,8 @@
 Lossless conversion between **Atlassian Document Format** (ADF), an extended markdown flavour, and
 an HTML dialect.
 
-**Status: scaffold only, no conversion code yet.** Plan: `todo.md`. Decisions: `AGENTS.md`.
+**Status: scaffold only, no conversion code yet.** Plan: `todo.md`. Decisions: `AGENTS.md`. The
+flavour's grammar: [`spec/flavour.md`](spec/flavour.md).
 
 ## What it is for
 

spec/flavour.md

@@ -0,0 +1,76 @@
+# The markdown flavour
+
+The grammar of the extended markdown `adfToMarkdown` emits and `markdownToAdf` parses. Plain
+CommonMark is a subset: the flavour adds directives, never changes CommonMark meaning. The emitted
+form is contract (AGENTS.md §8). Per-node syntaxes build on this grammar in sections that follow
+(todo.md 1b–1c).
+
+## Canonical form
+
+`adfToMarkdown` emits exactly one spelling; every CommonMark variant of the same document
+normalizes to it through the round-trip.
+
+- Emphasis `_em_`, strong `**strong**`; `*` replaces `_` only where `_` cannot parse
+  (intra-word).
+- Bullet lists `- `, two-space continuation indent. Ordered lists incrementing `1.` `2.` `3.`,
+  the first number taken from the node's `order` attribute.
+- ATX headings (`#` … `######`); setext input normalizes to ATX.
+- Code fences ``` with the node's language as info string, the fence lengthened past any backtick
+  run in the content; indented-code input normalizes to fences.
+- Thematic break `---`.
+- Hard break: backslash at end of line (survives editors that trim trailing spaces).
+- Links `[text](url)`; `<…>` around a destination containing spaces; title in double quotes;
+  `<url>` autolink when the link text equals its destination.
+- Paragraphs on one line — no soft wrapping; soft line breaks in input collapse per CommonMark.
+- Entity references in input decode to their characters; output backslash-escapes only where text
+  would otherwise parse as syntax.
+- Blocks separated by one blank line, no trailing whitespace, single trailing newline.
+
+## Directives
+
+One grammar for everything CommonMark lacks. Names are the ADF node names (camelCase).
+
+**Inline**: `:name[content]{attrs}`. `[content]` is inline markdown; each node's section says
+whether content and attrs are required. `:` opens a directive only when the name is followed
+immediately by `[` or `{` — anything else (`10:30`, `:smile:`) is literal text.
+
+**Container block**:
+
+```
+:::name arg {attrs}
+block content
+:::
+```
+
+The fence is three or more colons. `arg` is one optional bare token whose meaning each node
+defines (e.g. the panel type). The body is block markdown. The closing fence is a line of at
+least the opening's length, and a container's fence is longer than every directive fence line in
+its body, so closers are unambiguous — the code-fence rule. Canonical form uses minimal lengths.
+
+**Leaf block**: `::name {attrs}` — a block-position node with no body.
+
+**Attributes**: `{key=value key2="two words"}`. A bare value matches `[A-Za-z0-9_-]+`; anything
+else is double-quoted with `\"` and `\\` as the only escapes. All values are strings at the
+grammar level; each node's section assigns types. Canonical form orders keys alphabetically and
+spells values bare wherever allowed.
+
+**Escaping**: the emitter backslash-escapes a `:` whose text would otherwise parse as a
+directive; a backslash before `:` in input always yields a literal colon.
+
+## The opaque carry (AGENTS.md §3)
+
+A node type the library does not know rides as its raw JSON and restores to a deep-equal node:
+
+- **Block position**: a fenced code block with info string `adf`, body = the node's JSON,
+  serialized canonically — two-space indent, object keys sorted.
+- **Inline position**: `:adf{json="…"}`, same serialization, quote-escaped.
+
+The info string `adf` is reserved: a genuine `codeBlock` whose `language` is exactly `adf` is
+itself emitted through the opaque carry, so the reservation stays absolute and stays lossless.
+
+## Raw HTML in input
+
+CommonMark input may contain raw HTML. `markdownToAdf` routes each construct through the foreign
+HTML element mapping (AGENTS.md §3; specified with the HTML dialect, todo.md milestone 6) — ADF
+has no raw-HTML node, so a construct without a mapping, comments and processing instructions
+included, is an error result naming it. The flavour never emits raw HTML.

todo.md

@@ -8,11 +8,16 @@ detail is settled at its own milestone.
 - [x] **0 — Scaffold.** `package.json` per §6, `tsconfig.json`, `.npmrc` (`save-exact=true`), the
       Docker tooling, `renovate.json` (§9), and `.gitea/workflows/ci.yml` gating branches:
       `runs-on: docker-host`, actions pinned to semver tags.
-- [ ] **1 — The flavour spec.** The markdown flavour written as this repo's specification before
+- [x] **1a — The directive grammar** (`spec/flavour.md`): inline/block/leaf directive forms,
-      any implementation: the directive grammar (attributes, escaping, nesting), each node's
+      attributes, escaping, nesting, canonical form, the opaque-carry spelling, the raw-HTML
-      syntax from the inventory below, the opaque-carry spelling, the pipe-vs-directive table
+      input policy.
-      rule, and what CommonMark's raw-HTML constructs become in ADF, which has no raw-HTML node —
+- [ ] **1b — Block node syntaxes** in `spec/flavour.md`: panel, expand/nestedExpand, the media
-      likely the §3 element mapping, error otherwise. Start the corpus (§10) from this spec.
+      family, the pipe-vs-directive table rule and the directive table form, task and decision
+      lists, layout, extensions, syncBlock.
+- [ ] **1c — Inline node syntaxes and marks** in `spec/flavour.md`: mention, emoji, status, date,
+      inlineCard, mediaInline; underline, subsup, textColor, border.
+- [ ] **1d — Corpus start** (§10): checked-in ADF ↔ canonical-markdown fixture pairs per spec'd
+      node.
 - [ ] **2 — `adfToMarkdown`.** First real code — decide here where §10's coverage check lives.
 - [ ] **3 — `markdownToAdf`.** The CommonMark parser is the largest single component.
 - [ ] **4 — Round-trip property tests** over the corpus, both ways — the thing that proves 2 and 3.