Mirrors the existing @-mention system's shape: a regex finds #roomname
tokens, extract_referenced_room_ids validates them against rooms the
*sender* actually belongs to (mirrors mentions' "must be a real member"
rule -- referencing a private room the sender isn't in would otherwise
leak its existence), and a MessageRoomReference join row is stored per
match in create_message. No notification/unread layer, unlike mentions --
referencing a room has no "you were referenced" semantics.
Rendering is the same markdown-link rewrite trick MessageContent.tsx
already uses for mentions (#username -> [#username](mention:username)),
but resolved against the *viewer's* own room list (threaded down from
ChatShellPage's room state through ChatPane/MessageList) rather than the
stored server-side reference -- a reference to a room the current viewer
isn't in quietly renders as plain text instead of a link, same as an
@mention of someone outside the room does. The href scheme renders a
real react-router Link instead of mentions' inert span, since a room
reference is meant to be navigable.
mention_service.strip_code_spans (was _strip_code_spans) is now shared
between both extraction paths rather than private to one module.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
@username tokens in a sent message are parsed against the room's actual
members (skipping fenced/inline code, so pasted code isn't misread) and
recorded as MessageMention rows, reusing #38's read-tracking and
offline-member broadcast infrastructure rather than building a parallel
notification path:
- Sidebar: a mentioned-and-unread room shows a distinct highlight-
colored badge instead of (not alongside) the plain unread dot --
computed the same way as has_unread, just scoped to messages that
mention the caller, and cleared by the same last_read_at mark-read
flow.
- Push notifications: a mentioned offline recipient gets "X mentioned
you: ..." instead of the generic "X: ...", still per-recipient since
the same message can page some room members and not others.
- Message rendering: a validated @username is highlighted inline,
implemented by turning it into a `[@username](mention:username)` link
before markdown parsing and overriding link rendering to style
`mention:`-scheme links as a span instead of an anchor -- reuses
markdown-to-jsx's existing parser rather than hand-rolling text-node
splitting.
- Composer: typing @ opens an autocomplete dropdown of matching room
members (arrow keys to navigate, Enter/Tab/click to insert, Escape or
moving the cursor away to dismiss).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>