broomva/genesis/whatsapp-channel

The WhatsApp channel

Facts about what happens to a reply between you and the person reading it. All of it is measured against the running integration; none of it is advice.

You cannot send files

PostableThread exposes post(string | AsyncIterable<string>) and nothing else. There is no attachment path from this workspace.

A file you write to disk is real and the person cannot open it. So a reply whose substance lives in out/report.html delivers nothing — the message is the only thing that arrives. Write the file if it is useful to the repo; just never let it be the only place the answer exists.

Your markdown is rewritten

The reply is parsed as GitHub-flavoured markdown and re-rendered into WhatsApp's own syntax. Verified conversions:

Most constructs not listed above are rendered plainly rather than mangled, but not everything survives: a reference-style link loses its destination, and backslash escapes are consumed by the parser, so \*not emphasis\* reaches the person as *not emphasis* — which WhatsApp then renders as bold. Prefer inline links and avoid relying on escapes.

Tables specifically

A table becomes one block per row, not columns:

• the first column becomes a bold lead and its header is not shown — the

lead is the row's identity

• every other cell is labelled with its column header
• an empty cell is omitted entirely, label and all — except an empty FIRST

cell, which leaves a bare • because the row has no name to lead with

• a column with an empty header labels its value by position (2:) instead
• a row with more cells than headers labels the extras by position
• a header-only table (no body rows) becomes a plain bullet list of the headers

A wide table therefore expands vertically: every column becomes another labelled line under every row.

Long replies are split

CHUNK_TARGET is 1000 characters; the hard transport cap is 4096, above which a message is rejected outright. The rendered path reserves ten characters for fence balancing, so the effective split is ~990.

A longer reply is therefore delivered as several separate messages, in order, each a separate message. If a fenced code block spans a split, the fence is closed and reopened so both halves stay monospace.

You can only reply, and only for 24 hours

Free-form messages are permitted only within 24 hours of the person's last message to you (Meta error 131047, category reengagementWindow). Outside that window the send fails and they see nothing.

• There is no path that starts a conversation: every dispatch begins from an

inbound message.

• Within an active turn you can take as long as you need — a long-running job's

result is posted when it finishes.

• What you cannot do is reach them after the turn ends. Work that outlives

the turn has no callback path, so nothing may be designed around notifying them later.