feat: Support rendering multiple emails (#13882)

* first pass multiple email filter

- Handles original format with document level subject and other divs by producing exactly one email per document.
- subject and email_text divs must be nested within email divs to render multiple emails per document.
- email output now uses send_report_as_attachment instead of rsc_email_suppress_report_attachment

* change v1 trigger to the existence of top level metadata

and rename index field in json output to email_id

* sniff for connect version

* refactor connect verison logic

* ensure v1 email previewing

* update tests

* test with divs outside of the email div

* rename email-subject-document-level.qmd

* re-factor to enforce v1 output with non-nested structured input

* remove logs and some warnings

* add multi-email tests

* resolve bug with conflicting email-scheduled fields

might be prudent just to ignore, since this is a relic of accepting invalid input

* import connectversion module as object

* Add entry to changelog 1.9

Author: juleswg23

news/changelog-1.9.md

@@ -27,6 +27,10 @@ All changes included in 1.9:
 - ([#13421](https://github.com/quarto-dev/quarto-cli/issues/13421)): Do not word-wrap titles in header.
 - ([#13603](https://github.com/quarto-dev/quarto-cli/issues/13603)): Fix callouts with title but no body content causing fatal error when rendering to GitHub Flavored Markdown.
 
+### `email`
+
+- ([#13882](https://github.com/quarto-dev/quarto-cli/pull/13882)): Add support for multiple email outputs when rendering to `format: email` for Posit Connect.
+
 ### `html`
 
 - ([#11929](https://github.com/quarto-dev/quarto-cli/issues/11929)): Import all `brand.typography.fonts` in CSS, whether or not fonts are referenced by typography elements.

src/resources/filters/modules/connectversion.lua

@@ -0,0 +1,74 @@
+--[[
+Connect version sniffing utilities for email extension
+
+Functions to detect and compare Posit Connect versions from environment variables
+]]
+
+-- Parse Connect version from SPARK_CONNECT_USER_AGENT
+-- Format:  posit-connect/2024.09.0
+--          posit-connect/2024.09.0-dev+26-dirty-g51b853f70e
+-- Returns: "2024.09.0" or nil
+function get_connect_version()
+  local user_agent = os.getenv("SPARK_CONNECT_USER_AGENT")
+  if not user_agent then
+    return nil
+  end
+  
+  -- Extract the version after "posit-connect/"
+  local version_with_suffix = string.match(user_agent, "posit%-connect/([%d%.%-+a-z]+)")
+  if not version_with_suffix then
+    return nil
+  end
+  
+  -- Strip everything after the first "-" (e.g., "-dev+88-gda902918eb")
+  local idx = string.find(version_with_suffix, "-")
+  if idx then
+    return string.sub(version_with_suffix, 1, idx - 1)
+  end
+  
+  return version_with_suffix
+end
+
+-- Parse a version string into components
+-- Versions are in format "X.Y.Z", with all integral components (e.g., "2025.11.0")
+-- Returns: {major=2025, minor=11, patch=0} or nil
+function parse_version_components(version_string)
+  if not version_string then
+    return nil
+  end
+  
+  -- Parse version (e.g., "2025.11.0" or "2025.11")
+  local major, minor, patch = string.match(version_string, "^(%d+)%.(%d+)%.?(%d*)$")
+  if not major then
+    return nil
+  end
+  
+  return {
+    major = tonumber(major),
+    minor = tonumber(minor),
+    patch = patch ~= "" and tonumber(patch) or 0
+  }
+end
+
+-- Check if Connect version is >= target version
+-- Versions are in format "YYYY.MM.patch" (e.g., "2025.11.0")
+function is_connect_version_at_least(target_version)
+  local current_version = get_connect_version()
+  local current = parse_version_components(current_version)
+  local target = parse_version_components(target_version)
+  
+  if not current or not target then
+    return false
+  end
+  
+  -- Convert to numeric YYYYMMPP format and compare
+  local current_num = current.major * 10000 + current.minor * 100 + current.patch
+  local target_num = target.major * 10000 + target.minor * 100 + target.patch
+  
+  return current_num >= target_num
+end
+
+-- Export functions for module usage
+return {
+  is_connect_version_at_least = is_connect_version_at_least
+}

src/resources/filters/modules/constants.lua

@@ -164,6 +164,10 @@ local kBackgroundColorCaution = "ffe5d0"
 local kIncremental = "incremental"
 local kNonIncremental = "nonincremental"
 
+-- Connect version requirements
+-- TODO update version when email metadata changes are made in connect
+local kConnectEmailMetadataChangeVersion = "2026.03"
+
 return {
   kCitation = kCitation,
   kContainerId = kContainerId,
@@ -257,5 +261,7 @@ return {
   kBackgroundColorCaution = kBackgroundColorCaution,
 
   kIncremental = kIncremental,
-  kNonIncremental = kNonIncremental
+  kNonIncremental = kNonIncremental,
+
+  kConnectEmailMetadataChangeVersion = kConnectEmailMetadataChangeVersion
 }