{
  "description": "Composer serialization contract (issue #890): composer doc shape (the markdown.json tree vocabulary) -> exact wire bytes. The web serializer (composer-md.js serializeDoc) is the authority; the native twin (ComposerSerialize.swift) must emit identical bytes. `reparse` documents the accepted serialize-then-parse non-identities (expelled whitespace, code padding, typed double breaks becoming paragraphs); absent means parseMessage(md) returns the input tree. Scope notes: no nested blocks, no links from typing, no breaks inside list items — unreachable from composer typing on both platforms (web binds neither sinkListItem nor Tab; native has literal edit-load and plain paste). When a twin disagrees, fix the implementation, never the vector.",
  "vectors": [
    {
      "name": "plain_single",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "text",
              "text": "hello"
            }
          ]
        }
      ],
      "md": "hello"
    },
    {
      "name": "plain_multiline",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "text",
              "text": "a"
            },
            {
              "t": "br"
            },
            {
              "t": "text",
              "text": "b"
            }
          ]
        }
      ],
      "md": "a\nb",
      "note": "hard_break is a plain \\n on the wire"
    },
    {
      "name": "double_break",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "text",
              "text": "a"
            },
            {
              "t": "br"
            },
            {
              "t": "br"
            },
            {
              "t": "text",
              "text": "b"
            }
          ]
        }
      ],
      "md": "a\n\nb",
      "reparse": [
        {
          "t": "p",
          "children": [
            {
              "t": "text",
              "text": "a"
            }
          ]
        },
        {
          "t": "p",
          "children": [
            {
              "t": "text",
              "text": "b"
            }
          ]
        }
      ],
      "note": "two typed breaks read back as two paragraphs"
    },
    {
      "name": "bold",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "strong",
              "children": [
                {
                  "t": "text",
                  "text": "b"
                }
              ]
            }
          ]
        }
      ],
      "md": "**b**"
    },
    {
      "name": "italic",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "em",
              "children": [
                {
                  "t": "text",
                  "text": "i"
                }
              ]
            }
          ]
        }
      ],
      "md": "*i*"
    },
    {
      "name": "strike_single_tilde",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "strike",
              "children": [
                {
                  "t": "text",
                  "text": "s"
                }
              ]
            }
          ]
        }
      ],
      "md": "~s~",
      "note": "single tilde — old clients render it perfectly"
    },
    {
      "name": "inline_code",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "code",
              "text": "c"
            }
          ]
        }
      ],
      "md": "`c`"
    },
    {
      "name": "bold_italic",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "em",
              "children": [
                {
                  "t": "strong",
                  "children": [
                    {
                      "t": "text",
                      "text": "bi"
                    }
                  ]
                }
              ]
            }
          ]
        }
      ],
      "md": "***bi***",
      "note": "mark rank: em outermost"
    },
    {
      "name": "strong_strike",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "strong",
              "children": [
                {
                  "t": "strike",
                  "children": [
                    {
                      "t": "text",
                      "text": "x"
                    }
                  ]
                }
              ]
            }
          ]
        }
      ],
      "md": "**~x~**"
    },
    {
      "name": "em_strike",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "em",
              "children": [
                {
                  "t": "strike",
                  "children": [
                    {
                      "t": "text",
                      "text": "x"
                    }
                  ]
                }
              ]
            }
          ]
        }
      ],
      "md": "*~x~*"
    },
    {
      "name": "em_strong_strike",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "em",
              "children": [
                {
                  "t": "strong",
                  "children": [
                    {
                      "t": "strike",
                      "children": [
                        {
                          "t": "text",
                          "text": "x"
                        }
                      ]
                    }
                  ]
                }
              ]
            }
          ]
        }
      ],
      "md": "***~x~***"
    },
    {
      "name": "mixable_continuation",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "strong",
              "children": [
                {
                  "t": "text",
                  "text": "bold "
                }
              ]
            },
            {
              "t": "em",
              "children": [
                {
                  "t": "strong",
                  "children": [
                    {
                      "t": "text",
                      "text": "inner"
                    }
                  ]
                }
              ]
            },
            {
              "t": "strong",
              "children": [
                {
                  "t": "text",
                  "text": " bold"
                }
              ]
            }
          ]
        }
      ],
      "md": "**bold *inner* bold**",
      "reparse": [
        {
          "t": "p",
          "children": [
            {
              "t": "strong",
              "children": [
                {
                  "t": "text",
                  "text": "bold "
                },
                {
                  "t": "em",
                  "children": [
                    {
                      "t": "text",
                      "text": "inner"
                    }
                  ]
                },
                {
                  "t": "text",
                  "text": " bold"
                }
              ]
            }
          ]
        }
      ],
      "note": "the already-open strong stays outside"
    },
    {
      "name": "escape_star_in_strong",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "strong",
              "children": [
                {
                  "t": "text",
                  "text": "a*b"
                }
              ]
            }
          ]
        }
      ],
      "md": "**a\\*b**",
      "note": "in-mark escapes only"
    },
    {
      "name": "escape_star_in_em",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "em",
              "children": [
                {
                  "t": "text",
                  "text": "2*3"
                }
              ]
            }
          ]
        }
      ],
      "md": "*2\\*3*"
    },
    {
      "name": "escape_tilde_in_strike",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "strike",
              "children": [
                {
                  "t": "text",
                  "text": "a~b"
                }
              ]
            }
          ]
        }
      ],
      "md": "~a\\~b~"
    },
    {
      "name": "zero_escape_plain",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "text",
              "text": "2*3 and ~x~ stay"
            }
          ]
        }
      ],
      "md": "2*3 and ~x~ stay",
      "reparse": [
        {
          "t": "p",
          "children": [
            {
              "t": "text",
              "text": "2*3 and "
            },
            {
              "t": "strike",
              "children": [
                {
                  "t": "text",
                  "text": "x"
                }
              ]
            },
            {
              "t": "text",
              "text": " stay"
            }
          ]
        }
      ],
      "note": "plain text serializes verbatim, never a backslash"
    },
    {
      "name": "code_tick_sizing",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "code",
              "text": "a`b"
            }
          ]
        }
      ],
      "md": "`` a`b ``",
      "note": "delimiters sized past inner backticks, space-padded"
    },
    {
      "name": "code_double_tick",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "code",
              "text": "a``b"
            }
          ]
        }
      ],
      "md": "``` a``b ```"
    },
    {
      "name": "code_space_padding",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "code",
              "text": " x "
            }
          ]
        }
      ],
      "md": "` x `",
      "reparse": [
        {
          "t": "p",
          "children": [
            {
              "t": "code",
              "text": "x"
            }
          ]
        }
      ]
    },
    {
      "name": "code_beside_marks",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "strong",
              "children": [
                {
                  "t": "text",
                  "text": "b"
                }
              ]
            },
            {
              "t": "text",
              "text": " "
            },
            {
              "t": "code",
              "text": "c"
            }
          ]
        }
      ],
      "md": "**b** `c`"
    },
    {
      "name": "expel_trailing_ws",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "strong",
              "children": [
                {
                  "t": "text",
                  "text": "a "
                }
              ]
            },
            {
              "t": "text",
              "text": "b"
            }
          ]
        }
      ],
      "md": "**a** b",
      "reparse": [
        {
          "t": "p",
          "children": [
            {
              "t": "strong",
              "children": [
                {
                  "t": "text",
                  "text": "a"
                }
              ]
            },
            {
              "t": "text",
              "text": " b"
            }
          ]
        }
      ],
      "note": "expelEnclosingWhitespace"
    },
    {
      "name": "expel_leading_ws",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "text",
              "text": "a"
            },
            {
              "t": "strong",
              "children": [
                {
                  "t": "text",
                  "text": " b"
                }
              ]
            }
          ]
        }
      ],
      "md": "a **b**",
      "reparse": [
        {
          "t": "p",
          "children": [
            {
              "t": "text",
              "text": "a "
            },
            {
              "t": "strong",
              "children": [
                {
                  "t": "text",
                  "text": "b"
                }
              ]
            }
          ]
        }
      ]
    },
    {
      "name": "ws_only_styled",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "text",
              "text": "a"
            },
            {
              "t": "strong",
              "children": [
                {
                  "t": "text",
                  "text": "  "
                }
              ]
            },
            {
              "t": "text",
              "text": "b"
            }
          ]
        }
      ],
      "md": "a  b",
      "reparse": [
        {
          "t": "p",
          "children": [
            {
              "t": "text",
              "text": "a  b"
            }
          ]
        }
      ],
      "note": "whitespace-only styled run collapses to bare whitespace"
    },
    {
      "name": "marked_break_spans",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "strong",
              "children": [
                {
                  "t": "text",
                  "text": "a"
                },
                {
                  "t": "br"
                },
                {
                  "t": "text",
                  "text": "b"
                }
              ]
            }
          ]
        }
      ],
      "md": "**a\nb**",
      "note": "select-across-lines ⌘B: the break carries the mark"
    },
    {
      "name": "unmarked_break_closes",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "strong",
              "children": [
                {
                  "t": "text",
                  "text": "a"
                }
              ]
            },
            {
              "t": "br"
            },
            {
              "t": "strong",
              "children": [
                {
                  "t": "text",
                  "text": "b"
                }
              ]
            }
          ]
        }
      ],
      "md": "**a**\n**b**",
      "note": "typed Shift+Enter: plain break closes and reopens the mark"
    },
    {
      "name": "break_mark_not_continuing",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "strong",
              "children": [
                {
                  "t": "text",
                  "text": "a"
                },
                {
                  "t": "br"
                }
              ]
            },
            {
              "t": "text",
              "text": "b"
            }
          ]
        }
      ],
      "md": "**a**\nb",
      "reparse": [
        {
          "t": "p",
          "children": [
            {
              "t": "strong",
              "children": [
                {
                  "t": "text",
                  "text": "a"
                }
              ]
            },
            {
              "t": "br"
            },
            {
              "t": "text",
              "text": "b"
            }
          ]
        }
      ],
      "note": "a break's mark drops when the mark doesn't continue"
    },
    {
      "name": "unicode_styled",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "strong",
              "children": [
                {
                  "t": "text",
                  "text": "líne ✨ emoji"
                }
              ]
            }
          ]
        }
      ],
      "md": "**líne ✨ emoji**"
    },
    {
      "name": "bullet_list",
      "tree": [
        {
          "t": "ul",
          "items": [
            [
              {
                "t": "p",
                "children": [
                  {
                    "t": "text",
                    "text": "a"
                  }
                ]
              }
            ],
            [
              {
                "t": "p",
                "children": [
                  {
                    "t": "text",
                    "text": "b"
                  }
                ]
              }
            ]
          ]
        }
      ],
      "md": "- a\n- b"
    },
    {
      "name": "bullet_styled_item",
      "tree": [
        {
          "t": "ul",
          "items": [
            [
              {
                "t": "p",
                "children": [
                  {
                    "t": "strong",
                    "children": [
                      {
                        "t": "text",
                        "text": "b"
                      }
                    ]
                  },
                  {
                    "t": "text",
                    "text": " x"
                  }
                ]
              }
            ]
          ]
        }
      ],
      "md": "- **b** x"
    },
    {
      "name": "ordered_basic",
      "tree": [
        {
          "t": "ol",
          "start": 1,
          "items": [
            [
              {
                "t": "p",
                "children": [
                  {
                    "t": "text",
                    "text": "a"
                  }
                ]
              }
            ],
            [
              {
                "t": "p",
                "children": [
                  {
                    "t": "text",
                    "text": "b"
                  }
                ]
              }
            ]
          ]
        }
      ],
      "md": "1. a\n2. b"
    },
    {
      "name": "ordered_start3",
      "tree": [
        {
          "t": "ol",
          "start": 3,
          "items": [
            [
              {
                "t": "p",
                "children": [
                  {
                    "t": "text",
                    "text": "a"
                  }
                ]
              }
            ],
            [
              {
                "t": "p",
                "children": [
                  {
                    "t": "text",
                    "text": "b"
                  }
                ]
              }
            ]
          ]
        }
      ],
      "md": "3. a\n4. b"
    },
    {
      "name": "ordered_width_start9",
      "tree": [
        {
          "t": "ol",
          "start": 9,
          "items": [
            [
              {
                "t": "p",
                "children": [
                  {
                    "t": "text",
                    "text": "a"
                  }
                ]
              }
            ],
            [
              {
                "t": "p",
                "children": [
                  {
                    "t": "text",
                    "text": "b"
                  }
                ]
              }
            ]
          ]
        }
      ],
      "md": " 9. a\n10. b",
      "note": "width from digits(start+count-1): ' 9. a' aligns under '10. b'"
    },
    {
      "name": "ordered_ten_items",
      "tree": [
        {
          "t": "ol",
          "start": 1,
          "items": [
            [
              {
                "t": "p",
                "children": [
                  {
                    "t": "text",
                    "text": "item1"
                  }
                ]
              }
            ],
            [
              {
                "t": "p",
                "children": [
                  {
                    "t": "text",
                    "text": "item2"
                  }
                ]
              }
            ],
            [
              {
                "t": "p",
                "children": [
                  {
                    "t": "text",
                    "text": "item3"
                  }
                ]
              }
            ],
            [
              {
                "t": "p",
                "children": [
                  {
                    "t": "text",
                    "text": "item4"
                  }
                ]
              }
            ],
            [
              {
                "t": "p",
                "children": [
                  {
                    "t": "text",
                    "text": "item5"
                  }
                ]
              }
            ],
            [
              {
                "t": "p",
                "children": [
                  {
                    "t": "text",
                    "text": "item6"
                  }
                ]
              }
            ],
            [
              {
                "t": "p",
                "children": [
                  {
                    "t": "text",
                    "text": "item7"
                  }
                ]
              }
            ],
            [
              {
                "t": "p",
                "children": [
                  {
                    "t": "text",
                    "text": "item8"
                  }
                ]
              }
            ],
            [
              {
                "t": "p",
                "children": [
                  {
                    "t": "text",
                    "text": "item9"
                  }
                ]
              }
            ],
            [
              {
                "t": "p",
                "children": [
                  {
                    "t": "text",
                    "text": "item10"
                  }
                ]
              }
            ]
          ]
        }
      ],
      "md": " 1. item1\n 2. item2\n 3. item3\n 4. item4\n 5. item5\n 6. item6\n 7. item7\n 8. item8\n 9. item9\n10. item10"
    },
    {
      "name": "quote_single",
      "tree": [
        {
          "t": "quote",
          "children": [
            {
              "t": "p",
              "children": [
                {
                  "t": "text",
                  "text": "q"
                }
              ]
            }
          ]
        }
      ],
      "md": "> q"
    },
    {
      "name": "quote_styled",
      "tree": [
        {
          "t": "quote",
          "children": [
            {
              "t": "p",
              "children": [
                {
                  "t": "strong",
                  "children": [
                    {
                      "t": "text",
                      "text": "b"
                    }
                  ]
                },
                {
                  "t": "text",
                  "text": " i"
                }
              ]
            }
          ]
        }
      ],
      "md": "> **b** i"
    },
    {
      "name": "quote_multiline",
      "tree": [
        {
          "t": "quote",
          "children": [
            {
              "t": "p",
              "children": [
                {
                  "t": "text",
                  "text": "a"
                },
                {
                  "t": "br"
                },
                {
                  "t": "text",
                  "text": "b"
                }
              ]
            }
          ]
        }
      ],
      "md": "> a\n> b"
    },
    {
      "name": "quote_double_break",
      "tree": [
        {
          "t": "quote",
          "children": [
            {
              "t": "p",
              "children": [
                {
                  "t": "text",
                  "text": "a"
                },
                {
                  "t": "br"
                },
                {
                  "t": "br"
                },
                {
                  "t": "text",
                  "text": "b"
                }
              ]
            }
          ]
        }
      ],
      "md": "> a\n> \n> b",
      "reparse": [
        {
          "t": "quote",
          "children": [
            {
              "t": "p",
              "children": [
                {
                  "t": "text",
                  "text": "a"
                }
              ]
            },
            {
              "t": "p",
              "children": [
                {
                  "t": "text",
                  "text": "b"
                }
              ]
            }
          ]
        }
      ],
      "note": "the blank quoted line carries a trailing space"
    },
    {
      "name": "fence_plain",
      "tree": [
        {
          "t": "codeblock",
          "text": "code",
          "lang": ""
        }
      ],
      "md": "```\ncode\n```"
    },
    {
      "name": "fence_lang",
      "tree": [
        {
          "t": "codeblock",
          "text": "code **here**",
          "lang": "js"
        }
      ],
      "md": "```js\ncode **here**\n```"
    },
    {
      "name": "fence_inner_backticks",
      "tree": [
        {
          "t": "codeblock",
          "text": "x = ```\ny",
          "lang": ""
        }
      ],
      "md": "````\nx = ```\ny\n````"
    },
    {
      "name": "fence_empty",
      "tree": [
        {
          "t": "codeblock",
          "text": "",
          "lang": ""
        }
      ],
      "md": "```\n```"
    },
    {
      "name": "fence_tildes_stay",
      "tree": [
        {
          "t": "codeblock",
          "text": "~~~",
          "lang": ""
        }
      ],
      "md": "```\n~~~\n```",
      "note": "tildes never grow a backtick fence"
    },
    {
      "name": "mixed_blocks",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "text",
              "text": "intro"
            }
          ]
        },
        {
          "t": "ul",
          "items": [
            [
              {
                "t": "p",
                "children": [
                  {
                    "t": "text",
                    "text": "one"
                  }
                ]
              }
            ],
            [
              {
                "t": "p",
                "children": [
                  {
                    "t": "text",
                    "text": "two"
                  }
                ]
              }
            ]
          ]
        },
        {
          "t": "quote",
          "children": [
            {
              "t": "p",
              "children": [
                {
                  "t": "text",
                  "text": "bye"
                }
              ]
            }
          ]
        }
      ],
      "md": "intro\n\n- one\n- two\n\n> bye"
    },
    {
      "name": "para_then_list",
      "tree": [
        {
          "t": "p",
          "children": [
            {
              "t": "text",
              "text": "a"
            },
            {
              "t": "br"
            },
            {
              "t": "text",
              "text": "b"
            }
          ]
        },
        {
          "t": "ul",
          "items": [
            [
              {
                "t": "p",
                "children": [
                  {
                    "t": "text",
                    "text": "x"
                  }
                ]
              }
            ]
          ]
        }
      ],
      "md": "a\nb\n\n- x"
    }
  ]
}