---
summary: "Markdown formatting pipeline for outbound channels"
read_when:
  - You are changing markdown formatting or chunking for outbound channels
  - You are adding a new channel formatter or style mapping
  - You are debugging formatting regressions across channels
---
# Markdown formatting

Moltbot formats outbound Markdown by converting it into a shared intermediate
representation (IR) before rendering channel-specific output. The IR keeps the
source text intact while carrying style/link spans so chunking and rendering can
stay consistent across channels.

## Goals

- **Consistency:** one parse step, multiple renderers.
- **Safe chunking:** split text before rendering so inline formatting never
  breaks across chunks.
- **Channel fit:** map the same IR to Slack mrkdwn, Telegram HTML, and Signal
  style ranges without re-parsing Markdown.

## Pipeline

1. **Parse Markdown -> IR**
   - IR is plain text plus style spans (bold/italic/strike/code/spoiler) and link spans.
   - Offsets are UTF-16 code units so Signal style ranges align with its API.
   - Tables are parsed only when a channel opts into table conversion.
2. **Chunk IR (format-first)**
   - Chunking happens on the IR text before rendering.
   - Inline formatting does not split across chunks; spans are sliced per chunk.
3. **Render per channel**
   - **Slack:** mrkdwn tokens (bold/italic/strike/code), links as `<url|label>`.
   - **Telegram:** HTML tags (`<b>`, `<i>`, `<s>`, `<code>`, `<pre><code>`, `<a href>`).
   - **Signal:** plain text + `text-style` ranges; links become `label (url)` when label differs.

## IR example

Input Markdown:

```markdown
Hello **world** — see [docs](https://docs.molt.bot).
```

IR (schematic):

```json
{
  "text": "Hello world — see docs.",
  "styles": [
    { "start": 6, "end": 11, "style": "bold" }
  ],
  "links": [
    { "start": 19, "end": 23, "href": "https://docs.molt.bot" }
  ]
}
```

## Where it is used

- Slack, Telegram, and Signal outbound adapters render from the IR.
- Other channels (WhatsApp, iMessage, MS Teams, Discord) still use plain text or
  their own formatting rules, with Markdown table conversion applied before
  chunking when enabled.

## Table handling

Markdown tables are not consistently supported across chat clients. Use
`markdown.tables` to control conversion per channel (and per account).

- `code`: render tables as code blocks (default for most channels).
- `bullets`: convert each row into bullet points (default for Signal + WhatsApp).
- `off`: disable table parsing and conversion; raw table text passes through.

Config keys:

```yaml
channels:
  discord:
    markdown:
      tables: code
    accounts:
      work:
        markdown:
          tables: off
```

## Chunking rules

- Chunk limits come from channel adapters/config and are applied to the IR text.
- Code fences are preserved as a single block with a trailing newline so channels
  render them correctly.
- List prefixes and blockquote prefixes are part of the IR text, so chunking
  does not split mid-prefix.
- Inline styles (bold/italic/strike/inline-code/spoiler) are never split across
  chunks; the renderer reopens styles inside each chunk.

If you need more on chunking behavior across channels, see
[Streaming + chunking](/concepts/streaming).

## Link policy

- **Slack:** `[label](url)` -> `<url|label>`; bare URLs remain bare. Autolink
  is disabled during parse to avoid double-linking.
- **Telegram:** `[label](url)` -> `<a href="url">label</a>` (HTML parse mode).
- **Signal:** `[label](url)` -> `label (url)` unless label matches the URL.

## Spoilers

Spoiler markers (`||spoiler||`) are parsed only for Signal, where they map to
SPOILER style ranges. Other channels treat them as plain text.

## How to add or update a channel formatter

1. **Parse once:** use the shared `markdownToIR(...)` helper with channel-appropriate
   options (autolink, heading style, blockquote prefix).
2. **Render:** implement a renderer with `renderMarkdownWithMarkers(...)` and a
   style marker map (or Signal style ranges).
3. **Chunk:** call `chunkMarkdownIR(...)` before rendering; render each chunk.
4. **Wire adapter:** update the channel outbound adapter to use the new chunker
   and renderer.
5. **Test:** add or update format tests and an outbound delivery test if the
   channel uses chunking.

## Common gotchas

- Slack angle-bracket tokens (`<@U123>`, `<#C123>`, `<https://...>`) must be
  preserved; escape raw HTML safely.
- Telegram HTML requires escaping text outside tags to avoid broken markup.
- Signal style ranges depend on UTF-16 offsets; do not use code point offsets.
- Preserve trailing newlines for fenced code blocks so closing markers land on
  their own line.
