Signatures render into the main document - the identity form's live preview
and the composer's signature block - rather than the sandboxed iframe used for
message bodies. SIGNATURE_SANITIZE_CONFIG allows no target attribute, so those
anchors were live and target-less: one click navigated the whole app away,
discarding the unsent draft or the unsaved signature with it.
Add sanitizeSignatureHtmlForDisplay, which keeps the storage sanitizer's image
restrictions but forces target="_blank" rel="noopener noreferrer" on every
anchor, and use it at the two render sites. The composer's SignatureBlock
NodeView stamps the target on its rendered DOM instead, because attrs.html is
what serializeEditorContent emits into the sent message - storage and the
recipient's copy stay exactly as the user wrote them.
Rich, table-based identity signatures lost all their inline CSS
(background/text colors, fonts, border-radius, bgcolor). The composer
embeds the signature into the TipTap editor, and parsing it into the
ProseMirror schema flattened it to a generic bordered table. That
normalized version was then shown while composing AND delivered to the
recipient, even though Identity settings stored and previewed it
correctly.
Hold the signature as a dedicated, non-editable atom node
(SignatureBlock) that keeps the verbatim HTML in an attribute and renders
it inside a Shadow Root, mirroring the existing QuotedHtml island. The
markup is never parsed into the schema, so the styling survives 1:1 both
in the in-editor preview and in the outgoing mail
(serializeEditorContent inlines the verbatim HTML, as it already does for
quoted originals). The signature stays a single unit: select it and
Backspace/Delete to remove it; identity switching still swaps it via the
existing data-signature-block markers.
Adds unit coverage (parse + serialize round-trip preserves inline styles).
Fixes#475
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
