@@ -397,15 +397,85 @@
 		end;
 	};
 }
 
--- renderer engines
-function ct.render.html(doc, opts)
-	local doctitle = opts['title']
-	local f = string.format
+-- common renderer utility functions
+ct.tool = {}
+
+function ct.tool.mathfmt(ctx, eqn)
+	local buf = ''
+	local m = ss.enum {'num','var','op'}
+	local lsc = 0
+	local spans = {}
+
+	local flush = function()
+		local o
+		if buf ~= '' then
+			if lsc == 0 then
+				o = buf
+			elseif lsc == m.num then
+				o = {
+					kind = 'format';
+					style = 'literal';
+					spans = {buf};
+				}
+			elseif lsc == m.var then
+				o = {
+					kind = 'format';
+					style = 'variable';
+					spans = {buf};
+				}
+			elseif lsc == m.op then
+				o = {
+					kind = 'format';
+					style = 'strong';
+					spans = {buf};
+				}
+			end
+			if o then
+				table.insert(spans, o)
+			end
+		end
+		buf = ''
+		lsc = 0
+	end
+
+	for c, p in ss.str.each(ctx.doc.enc, eqn) do
+		local cl = ss.str.classify(ctx.doc.enc, c)
+		local nc = 0
+		if not cl.space then
+			if cl.numeral then
+				nc = m.num
+			elseif cl.mathop or cl.symbol then
+				nc = m.op
+			elseif cl.letter then
+				nc = m.var
+			end
+			if nc ~= lsc then
+				flush()
+				lsc = nc
+			end
+			buf = buf .. c
+		end
+	end
+	flush()
+	return spans
+end
+
+function ct.tool.namespace()
+-- some renderers need to be able to generate unique IDs for
+-- objects, including ones that users have not assigned IDs
+-- to, and objects with the same name in different unlabeled
+-- sections. to handle this, we provide a "namespace" mechanism,
+-- where some lua table (really its address in memory) is used
+-- as a handle for the object and a unique ID is attached to it.
+-- if the object has an ID of its own, it is guaranteed to be
+-- unique and returned; otherwise, a generic id of the form
+-- `x-%u` is generated, where %u is an integer that increments
+-- for every new object
 	local ids = {}
 	local canonicalID = {}
-	local function getSafeID(obj,pfx)
+	return function(obj,pfx)
 		pfx = pfx or ''
 		if canonicalID[obj] then
 			return canonicalID[obj]
 		elseif obj.id and ids[pfx .. obj.id] then
@@ -428,915 +498,11 @@
 			canonicalID[obj] = cid
 			return cid
 		end
 	end
-
-	local footnotes = {}
-	local footnotecount = 0
-
-	local langsused = {}
-	local langpairs = {
-		lua = { color = 0x9377ff };
-		terra = { color = 0xff77c8 };
-		c = { name = 'C', color = 0x77ffe8 };
-		html = { color = 0xfff877 };
-		scheme = { color = 0x77ff88 };
-		lisp = { color = 0x77ff88 };
-		fortran = { color = 0xff779a };
-		python = { color = 0xffd277 };
-		ruby = { color = 0xcdd6ff };
-	}
-
-	local stylesets = {
-		footnote = [[
-			div.footnote {
-			font-family: 90%;
-				display: none;
-				grid-template-columns: 1em 1fr min-content;
-				grid-template-rows: 1fr min-content;
-				position: fixed;
-				padding: 1em;
-				background: @tone(0.05);
-				border: black;
-				margin:auto;
-			}
-			div.footnote:target { display:grid; }
-			@media screen {
-				div.footnote {
-					left: 10em;
-					right: 10em;
-					max-width: calc(@width + 2em);
-					max-height: 30vw;
-					bottom: 1em;
-				}
-			}
-			@media print {
-				div.footnote {
-					position: relative;
-				}
-				div.footnote:first-of-type {
-					border-top: 1px solid black;
-				}
-			}
-
-			div.footnote > a[href="#0"]{
-				grid-row: 2/3;
-				grid-column: 3/4;
-				display: block;
-				padding: 0.2em 0.7em;
-				text-align: center;
-				text-decoration: none;
-				background: @tone(0.2);
-				color: @tone(1);
-				border: 1px solid black;
-				margin-top: 0.6em;
-				-webkit-user-select: none;
-				-ms-user-select: none;
-				user-select: none;
-				-webkit-user-drag: none;
-				user-drag: none;
-			}
-			div.footnote > a[href="#0"]:hover {
-				background: @tone(0.3);
-				color: @tone(2);
-			}
-			div.footnote > a[href="#0"]:active {
-				background: @tone(0.05);
-				color: @tone(0.4);
-			}
-			@media print {
-				div.footnote > a[href="#0"]{
-					display:none;
-				}
-			}
-			div.footnote > div.number {
-				text-align:right;
-				grid-row: 1/2;
-				grid-column: 1/2;
-			}
-			div.footnote > div.text {
-				grid-row: 1/2;
-				grid-column: 2/4;
-				padding-left: 1em;
-				overflow-y: scroll;
-			}
-		]];
-		header = [[
-			body { padding: 0 2.5em !important }
-			h1,h2,h3,h4,h5,h6 { border-bottom: 1px solid @tone(0.7); }
-			h1 { font-size: 200%; border-bottom-style: double !important; border-bottom-width: 3px !important; margin: 0em -1em; }
-			h2 { font-size: 130%; margin: 0em -0.7em; }
-			h3 { font-size: 110%; margin: 0em -0.5em; }
-			h4 { font-size: 100%; font-weight: normal; margin: 0em -0.2em; }
-			h5 { font-size: 90%; font-weight: normal; }
-			h6 { font-size: 80%; font-weight: normal; }
-			h3, h4, h5, h6 { border-bottom-style: dotted !important; }
-			h1,h2,h3,h4,h5,h6 { 
-				margin-top: 0;
-				margin-bottom: 0;
-			}
-			:is(h1,h2,h3,h4,h5,h6) + p {
-				margin-top: 0.4em;
-			}
-
-		]];
-		headingAnchors = [[
-			:is(h1,h2,h3,h4,h5,h6) > a[href].anchor {
-				text-decoration: none;
-				font-size: 1.2em;
-				padding: 0.3em;
-				opacity: 0%;
-				transition: 0.3s;
-				font-weight: 100;
-			}
-			:is(h1,h2,h3,h4,h5,h6):hover > a[href].anchor {
-				opacity: 50%;
-			}
-			:is(h1,h2,h3,h4,h5,h6) > a[href].anchor:hover {
-				opacity: 100%;
-			}
-
-			]] .. -- this is necessary to avoid the sections jumping around
-			      -- when focus changes from one to another
-			[[ section {
-				border: 1px solid transparent;
-			}
-
-			section:target {
-				margin-left: -2em;
-				margin-right: -2em;
-				padding: 0 2em;
-				background: @tone(0.04);
-				border: 1px dotted @tone(0.3);
-			}
-
-			section:target > :is(h1,h2,h3,h4,h5,h6) {
-
-			}
-		]];
-		paragraph = [[
-			p {
-				margin: 0.7em 0;
-				text-align: justify;
-			}
-			section {
-				margin: 1.2em 0;
-			}
-			section:first-child { margin-top: 0; }
-		]];
-		accent = [[
-			@media screen {
-				body { background: @bg; color: @fg }
-				a[href] {
-					color: @tone(0.7 30);
-					text-decoration-color: @tone/0.4(0.7 30);
-				}
-				a[href]:hover {
-					color: @tone(0.9 30);
-					text-decoration-color: @tone/0.7(0.7 30);
-				}
-				h1 { color: @tone(2); }
-				h2 { color: @tone(1.5); }
-				h3 { color: @tone(1.2); }
-				h4 { color: @tone(1); }
-				h5,h6 { color: @tone(0.8); }
-			}
-			@media print {
-				a[href] {
-					text-decoration: none;
-					color: black;
-					font-weight: bold;
-				}
-				h1,h2,h3,h4,h5,h6 {
-					border-bottom: 1px black;
-				}
-			}
-		]];
-		aside = [[
-			section > aside {
-				text-align: justify;
-				margin: 0 1.5em;
-				padding: 0.5em 0.8em;
-				background: @tone(0.05);
-				font-size: 90%;
-				border-left: 5px solid @tone(0.2 15);
-				border-right: 5px solid @tone(0.2 15);
-			}
-			section > aside p {
-				margin: 0;
-				margin-top: 0.6em;
-			}
-			section > aside p:first-child {
-				margin: 0;
-			}
-      ]];
-		code = [[
-			code {
-				display: inline-block;
-				background: @tone(0.9);
-				color: @bg;
-				font-family: monospace;
-				font-size: 90%;
-				padding: 3px 5px;
-			}
-		]];
-		var = [[
-			var {
-				font-style: italic;
-				font-family: monospace;
-				color: @tone(0.7);
-			}
-			code var {
-				color: @tone(0.25);
-			}
-		]];
-		math = [[
-			span.equation {
-				display: inline-block;
-				background: @tone(0.08);
-				color: @tone(2);
-				padding: 0.1em 0.3em;
-				border: 1px solid @tone(0.5);
-			}
-		]];
-		abbr = [[
-			abbr[title] { cursor: help; }
-		]];
-		editors_markup = [[]];
-		block_code_listing = [[
-			figure.listing {
-				font-family: monospace;
-				background: @tone(0.05);
-				color: @fg;
-				padding: 0;
-				margin: 0.3em 0;
-				counter-reset: line-number;
-				position: relative;
-				border: 1px solid @fg;
-			}
-			figure.listing>div {
-				white-space: pre-wrap;
-				tab-size: 3;
-				-moz-tab-size: 3;
-				counter-increment: line-number;
-				text-indent: -2.3em;
-				margin-left: 2.3em;
-			}
-			figure.listing>:is(div,hr)::before {
-				width: 1.0em;
-				padding: 0.2em 0.4em;
-				text-align: right;
-				display: inline-block;
-				background-color: @tone(0.2);
-				border-right: 1px solid @fg;
-				content: counter(line-number);
-				margin-right: 0.3em;
-			}
-			figure.listing>hr::before {
-				color: transparent;
-				padding-top: 0;
-				padding-bottom: 0;
-			}
-			figure.listing>div::before {
-				color: @fg;
-			}
-			figure.listing>div:last-child::before {
-				padding-bottom: 0.5em;
-			}
-			figure.listing>figcaption:first-child {
-				border: none;
-				border-bottom: 1px solid @fg;
-			}
-			figure.listing>figcaption::after {
-				display: block;
-				float: right;
-				font-weight: normal;
-				font-style: italic;
-				font-size: 70%;
-				padding-top: 0.3em;
-			}
-			figure.listing>figcaption {
-				font-family: sans-serif;
-				font-size: 120%;
-				padding: 0.2em 0.4em;
-				border: none;
-				color: @tone(2);
-			}
-			figure.listing > hr {
-				border: none;
-				margin: 0;
-				height: 0.7em;
-				counter-increment: line-number;
-			}
-		]];
-	}
-
-	local stylesNeeded = {}
-
-	local render_state_handle = {
-		doc = doc;
-		opts = opts;
-		style_rules = styles; -- use stylesneeded if at all possible
-		stylesets = stylesets;
-		stylesets_active = stylesNeeded;
-		obj_htmlid = getSafeID;
-		-- remaining fields added later
-	}
-
-	local renderJob = doc:job('render_html', nil, render_state_handle)
-	doc.stage.job = renderJob;
-
-	local runhook = function(h, ...)
-		return renderJob:hook(h, render_state_handle, ...)
-	end
-
-	local tagproc do
-		local elt = function(t,attrs)
-			return f('<%s%s>', t,
-				attrs and ss.reduce(function(a,b) return a..b end, '',
-					ss.map(function(v,k)
-						if v == true
-							then          return ' '..k
-							elseif v then return f(' %s="%s"', k, v)
-						end
-					end, attrs)) or '')
-		end
-
-		tagproc = {
-			toTXT = {
-				tag = function(t,a,v) return v  end;
-				elt = function(t,a)   return '' end;
-				catenate = table.concat;
-			};
-			toIR = {
-				tag = function(t,a,v,o) return {
-					tag = t, attrs = a;
-					nodes = type(v) == 'string' and {v} or v, src = o
-				} end;
-
-				elt = function(t,a,o) return {
-					tag = t, attrs = a, src = o
-				} end;
-
-				catenate = function(...) return ... end;
-			};
-			toHTML = {
-				elt = elt;
-				tag = function(t,attrs,body)
-					return f('%s%s</%s>', elt(t,attrs), body, t)
-				end;
-				catenate = table.concat;
-			};
-		}
-	end
-
-	local function getBaseRenderers(procs, span_renderers)
-		local tag, elt, catenate = procs.tag, procs.elt, procs.catenate
-		local htmlDoc = function(title, head, body)
-			return [[<!doctype html>]] .. tag('html',nil,
-				tag('head', nil,
-					elt('meta',{charset = 'utf-8'}) ..
-					(title and tag('title', nil, title) or '') ..
-					(head or '')) ..
-				tag('body', nil, body or ''))
-		end
-
-		local function htmlSpan(spans, block, sec)
-			local text = {}
-			for k,v in pairs(spans) do
-				if type(v) == 'string' then
-					v=v:gsub('[<>&"]', function(x)
-							return string.format('&#%02u;', string.byte(x))
-						end)
-					for fn, ext in renderJob:each('hook','render_html_sanitize') do
-						v = fn(renderJob:delegate(ext), v)
-					end
-					table.insert(text,v)
-				else
-					table.insert(text, (span_renderers[v.kind](v, block, sec)))
-				end
-			end
-			return table.concat(text)
-		end
-		return {htmlDoc=htmlDoc, htmlSpan=htmlSpan}
-	end
-
-	local spanparse = function(...)
-		local s = ct.parse_span(...)
-		doc.docjob:hook('meddle_span', s)
-		return s
-	end
-
-	local cssRulesFor = {}
-	local function getSpanRenderers(procs)
-		local tag, elt, catenate = procs.tag, procs.elt, procs.catenate
-		local span_renderers = {}
-		local plainrdr = getBaseRenderers(tagproc.toTXT, span_renderers)
-		local htmlSpan = getBaseRenderers(procs, span_renderers).htmlSpan
-
-		function span_renderers.format(sp,...)
-			local tags = { strong = 'strong', emph = 'em', strike = 'del', insert = 'ins', literal = 'code', variable = 'var'}
-			if sp.style == 'literal' and not opts['fossil-uv'] then
-				stylesNeeded.code = true
-			elseif sp.style == 'strike' or sp.style == 'insert' then
-				stylesNeeded.editors_markup = true
-			elseif sp.style == 'variable' then
-				stylesNeeded.var = true
-			end
-			return tag(tags[sp.style],nil,htmlSpan(sp.spans,...))
-		end
-
-		function span_renderers.deref(t,b,s)
-			local r = b.origin:ref(t.ref)
-			local name = t.ref
-			if name:find'%.' then name = name:match '^[^.]*%.(.+)$' end
-			if type(r) == 'string' then
-				stylesNeeded.abbr = true
-				return tag('abbr',{title=r},next(t.spans) and htmlSpan(t.spans,b,s) or name)
-			end
-			if r.kind == 'resource' then
-				local rid = getSafeID(r, 'res-')
-				if r.class == 'image' then
-					if not cssRulesFor[r] then
-						local css = prepcss(string.format([[
-							section p > .%s {
-							}
-						]], rid))
-						stylesets[r] = css
-						cssRulesFor[r] = css
-						stylesNeeded[r] = true
-					end
-					return tag('div',{class=rid},catenate{'blaah'})
-				elseif r.class == 'video' then
-					local vid = {}
-					return tag('video',nil,vid)
-				elseif r.class == 'font' then
-					b.origin:fail('fonts cannot be instantiated, use %font directive instead')
-				end
-			else
-				b.origin:fail('%s is not an object that can be embedded', t.ref)
-			end
-		end
-
-		function span_renderers.var(v,b,s)
-			local val
-			if v.pos then
-				if not v.origin.invocation then
-					v.origin:fail 'positional arguments can only be used in a macro invocation'
-				elseif not v.origin.invocation.args[v.pos] then
-					v.origin.invocation.origin:fail('macro invocation %s missing positional argument #%u', v.origin.invocation.macro, v.pos)
-				end
-				val = v.origin.invocation.args[v.pos]
-			else
-				val = v.origin.doc:context_var(v.var, v.origin)
-			end
-			if v.raw then
-				return val
-			else
-				return htmlSpan(ct.parse_span(val, v.origin), b, s)
-			end
-		end
-
-		function span_renderers.raw(v,b,s)
-			return htmlSpan(v.spans, b, s)
-		end
-
-		function span_renderers.link(sp,b,s)
-			local href
-			if b.origin.doc.sections[sp.ref] then
-				href = '#' .. sp.ref
-			else
-				if sp.addr then href = sp.addr else
-					local r = b.origin:ref(sp.ref)
-					if type(r) == 'table' then
-						href = '#' .. getSafeID(r)
-					else href = r end
-				end
-			end
-			return tag('a',{href=href},next(sp.spans) and htmlSpan(sp.spans,b,s) or href)
-		end
-
-		span_renderers['line-break'] = function(sp,b,s)
-			return elt('br')
-		end
-
-		function span_renderers.macro(m,b,s)
-			local macroname = plainrdr.htmlSpan(
-				ct.parse_span(m.macro, b.origin), b,s)
-			local r = b.origin:ref(macroname)
-			if type(r) ~= 'string' then
-				b.origin:fail('%s is an object, not a reference', t.ref)
-			end
-			local mctx = b.origin:clone()
-			mctx.invocation = m
-			return htmlSpan(ct.parse_span(r, mctx),b,s)
-		end
-		function span_renderers.math(m,b,s)
-			stylesNeeded.math = true
-			return tag('span',{class='equation'},htmlSpan(m.spans, b, s))
-		end;
-		function span_renderers.directive(d,b,s)
-			if d.ext == 'html' then
-			elseif b.origin.doc:allow_ext(d.ext) then
-			elseif d.crit then
-				b.origin:fail('critical extension %s unavailable', d.ext)
-			elseif d.failthru then
-				return htmlSpan(d.spans, b, s)
-			end
-		end
-		function span_renderers.footnote(f,b,s)
-			stylesNeeded.footnote = true
-			local source, sid, ssec = b.origin:ref(f.ref)
-			local cnc = getSafeID(ssec) .. ' ' .. sid
-			local fn
-			if footnotes[cnc] then
-				fn = footnotes[cnc]
-			else
-				footnotecount = footnotecount + 1
-				fn = {num = footnotecount, origin = b.origin, fnid=cnc, source = source}
-				fn.id = getSafeID(fn)
-				footnotes[cnc] = fn
-			end
-			return tag('a', {href='#'..fn.id}, htmlSpan(f.spans) ..
-						tag('sup',nil, fn.num))
-		end
-
-		return span_renderers
-	end
-
-	local function getBlockRenderers(procs, sr)
-		local tag, elt, catenate = procs.tag, procs.elt, procs.catenate
-		local null = function() return catenate{} end
-
-		local block_renderers = {
-			anchor = function(b,s)
-				return tag('a',{id = getSafeID(b)},null())
-			end;
-			paragraph = function(b,s)
-				stylesNeeded.paragraph = true;
-				return tag('p', nil, sr.htmlSpan(b.spans, b, s), b)
-			end;
-			directive = function(b,s)
-				-- deal with renderer directives
-				local _, cmd, args = b.words(2)
-				if cmd == 'page-title' then
-					if not opts.title then doctitle = args end
-				elseif b.critical then
-					b.origin:fail('critical HTML renderer directive “%s” not supported', cmd)
-				end
-			end;
-			label = function(b,s)
-				if ct.sec.is(b.captions) then
-					if not (opts['fossil-uv'] or opts.snippet) then
-						stylesNeeded.header = true
-					end
-					local h = math.min(6,math.max(1,b.captions.depth))
-					return tag(f('h%u',h), nil, sr.htmlSpan(b.spans, b, s), b)
-				else
-					-- handle other uses of labels here
-				end
-			end;
-			['list-item'] = function(b,s)
-				return tag('li', nil, sr.htmlSpan(b.spans, b, s), b)
-			end;
-			table = function(b,s)
-				local tb = {}
-				for i, r in ipairs(b.rows) do
-					local row = {}
-					for i, c in ipairs(r) do
-						table.insert(row, tag(c.header and 'th' or 'td',
-						{align=c.align}, sr.htmlSpan(c.spans, b)))
-					end
-					table.insert(tb, tag('tr',nil,catenate(row)))
-				end
-				return tag('table',nil,catenate(tb))
-			end;
-			listing = function(b,s)
-				stylesNeeded.block_code_listing = true
-				local nodes = ss.map(function(l)
-					if #l > 0 then
-						return tag('div',nil,sr.htmlSpan(l, b, s))
-					else
-						return elt('hr')
-					end
-				end, b.lines)
-				if b.title then
-					table.insert(nodes,1, tag('figcaption',nil,sr.htmlSpan(b.title)))
-				end
-				if b.lang then langsused[b.lang] = true end
-				return tag('figure', {class='listing', lang=b.lang, id=b.id and getSafeID(b)}, catenate(nodes))
-			end;
-			aside = function(b,s)
-				local bn = {}
-				stylesNeeded.aside = true
-				if #b.lines == 1 then
-					bn[1] = sr.htmlSpan(b.lines[1], b, s)
-				else
-					for _,v in pairs(b.lines) do
-						table.insert(bn, tag('p', {}, sr.htmlSpan(v, b, s)))
-					end
-				end
-				return tag('aside', {}, bn)
-			end;
-			['break'] = function() -- HACK
-				-- lists need to be rewritten to work like asides
-				return '';
-			end;
-		}
-		return block_renderers;
-	end
-
-	local function getRenderers(procs)
-		local span_renderers = getSpanRenderers(procs)
-		local r = getBaseRenderers(procs,span_renderers)
-		r.block_renderers = getBlockRenderers(procs, r)
-		return r
-	end
-
-	local astproc = {
-		toHTML = getRenderers(tagproc.toHTML);
-		toTXT  = getRenderers(tagproc.toTXT);
-		toIR   = { };
-	}
-	astproc.toIR.span_renderers = ss.clone(astproc.toHTML);
-	astproc.toIR.block_renderers = getBlockRenderers(tagproc.toIR,astproc.toHTML);
-		-- note we use HTML here instead of IR span renderers, because as things
-		-- currently stand we don't need that level of resolution. if we ever
-		-- get to the point where we want to be able to twiddle spans around
-		-- we'll need to introduce an IR span renderer
-
-	render_state_handle.astproc = astproc;
-	render_state_handle.tagproc = tagproc;
-
-	-- bind to legacy names
-	-- yikes this needs to be cleaned up so badly
-	local ir = {}
-	local dr = astproc.toHTML -- default renderers
-	local plainr = astproc.toTXT
-	local irBlockRdrs = astproc.toIR.block_renderers;
-
-	render_state_handle.ir = ir;
-
-	local function renderBlocks(blocks, irs)
-		for i, block in ipairs(blocks) do
-			local rd
-			if irBlockRdrs[block.kind] then
-				rd = irBlockRdrs[block.kind](block,sec)
-			else
-				local rdr = renderJob:proc('render',block.kind,'html')
-				if rdr then
-					rd = rdr({
-						state = render_state_handle;
-						tagproc = tagproc.toIR;
-						astproc = astproc.toIR;
-					}, block, sec)
-				end
-			end
-			if rd then
-				if opts['heading-anchors'] and block == sec.heading_node then
-					stylesNeeded.headingAnchors = true
-					table.insert(rd.nodes, ' ')
-					table.insert(rd.nodes, {
-						tag = 'a';
-						attrs = {href = '#' .. irs.attrs.id, class='anchor'};
-						nodes = {type(opts['heading-anchors'])=='string' and opts['heading-anchors'] or '&sect;'};
-					})
-				end
-				if rd.src and rd.src.origin.lang then
-					if not rd.attrs then rd.attrs = {} end
-					rd.attrs.lang = rd.src.origin.lang
-				end
-				table.insert(irs.nodes, rd)
-				runhook('ir_section_node_insert', rd, irs, sec)
-			end
-		end
-	end
-	runhook('ir_assemble', ir)
-	for i, sec in ipairs(doc.secorder) do
-		if doctitle == nil and sec.depth == 1 and sec.heading_node then
-			doctitle = astproc.toTXT.htmlSpan(sec.heading_node.spans, sec.heading_node, sec)
-		end
-		local irs
-		if sec.kind == 'ordinary' then
-			if #(sec.blocks) > 0 then
-				irs = {tag='section',attrs={id = getSafeID(sec)},nodes={}}
-				runhook('ir_section_build', irs, sec)
-				renderBlocks(sec.blocks, irs)
-			end
-		elseif sec.kind == 'blockquote' then
-		elseif sec.kind == 'listing' then
-		elseif sec.kind == 'embed' then
-		end
-		if irs then table.insert(ir, irs) end
-	end
-
-	for _, fn in pairs(footnotes) do
-		local tag = tagproc.toIR.tag
-		local body = {nodes={}}
-		local ftir = {}
-		for l in fn.source:gmatch('([^\n]*)') do
-			ct.parse_line(l, fn.origin, ftir)
-		end
-		renderBlocks(ftir,body)
-		local note = tag('div',{class='footnote',id=fn.id}, {
-			tag('div',{class='number'}, tostring(fn.num)),
-			tag('div',{class='text'}, body.nodes),
-			tag('a',{href='#0'},'close')
-		})
-		table.insert(ir, note)
-	end
-
-	-- restructure passes
-	runhook('ir_restructure_pre', ir)
-	
-	---- list insertion pass
-	local lists = {}
-	for _, sec in pairs(ir) do
-		if sec.tag == 'section' then
-			local i = 1 while i <= #sec.nodes do local v = sec.nodes[i]
-				if v.tag == 'li' then
-					local ltag
-					if v.src.ordered
-						then ltag = 'ol'
-						else ltag = 'ul'
-					end
-					local last = i>1 and sec.nodes[i-1]
-					if last and last.embed == 'list' and not (
-						last.ref[#last.ref].src.depth   == v.src.depth and
-						last.ref[#last.ref].src.ordered ~= v.src.ordered
-					) then
-						-- add to existing list
-						table.insert(last.ref, v)
-						table.remove(sec.nodes, i) i = i - 1
-					else
-						-- wrap in list
-						local newls = {v}
-						sec.nodes[i] = {embed = 'list', ref = newls}
-						table.insert(lists,newls)
-					end
-				end
-			i = i + 1 end
-		end
-	end
-
-	for _, sec in pairs(ir) do
-		if sec.tag == 'section' then
-			for i, elt in pairs(sec.nodes) do
-				if elt.embed == 'list' then
-					local function fail_nest()
-						elt.ref[1].src.origin:fail('improper list nesting')
-					end
-					local struc = {attrs={}, nodes={}}
-					if elt.ref[1].src.ordered then struc.tag = 'ol' else struc.tag = 'ul' end
-					if elt.ref[1].src.depth ~= 1 then fail_nest() end
-
-					local stack = {struc}
-					local copyNodes = function(old,new)
-						for i,v in ipairs(old) do new[#new + i] = v end
-					end
-					for i,e in ipairs(elt.ref) do
-						if e.src.depth > #stack then
-							if e.src.depth - #stack > 1 then fail_nest() end
-							local newls = {attrs={}, nodes={e}}
-							copyNodes(e.nodes,newls)
-							if e.src.ordered then newls.tag = 'ol' else newls.tag='ul' end
-							table.insert(stack[#stack].nodes[#stack[#stack].nodes].nodes, newls)
-							table.insert(stack, newls)
-						else
-							if e.src.depth < #stack then
-								-- pop entries off the stack
-								for i=#stack, e.src.depth+1, -1 do stack[i] = nil end
-							end
-							table.insert(stack[#stack].nodes, e)
-						end
-					end
-
-					sec.nodes[i] = struc
-				end
-			end
-		end
-	end
-	
-	runhook('ir_restructure_post', ir)
-
-	-- collection pass
-	local function collect_nodes(t)
-		local ts = ''
-		for i,v in ipairs(t) do
-			if type(v) == 'string' then
-				ts = ts .. v
-			elseif v.nodes then
-				ts = ts .. tagproc.toHTML.tag(v.tag, v.attrs, collect_nodes(v.nodes))
-			elseif v.text then
-				ts = ts .. tagproc.toHTML.tag(v.tag,v.attrs,v.text)
-			else
-				ts = ts .. tagproc.toHTML.elt(v.tag,v.attrs)
-			end
-		end
-		return ts
-	end
-	local body = collect_nodes(ir)
-
-	for k in pairs(langsused) do
-		local spec = langpairs[k] or {color=0xaaaaaa}
-		stylesets.block_code_listing = stylesets.block_code_listing .. string.format(
-			[[section > figure.listing[lang="%s"]>figcaption::after
-				{ content: '%s'; color: #%06x }]],
-			k, spec.name or k, spec.color)
-	end
-
-	local prepcss = function(css)
-		local tone = function(fac, sat, sep, alpha)
-			local hsl = function(h,s,l,a)
-				local v = string.format('%s, %u%%, %u%%', h,s,l)
-				if a then
-					return string.format('hsla(%s, %s)', v,a)
-				else
-					return string.format('hsl(%s)', v)
-				end
-			end
-			sat = sat or 1
-			fac = math.max(math.min(fac, 1), 0)
-			sat = math.max(math.min(sat, 1), 0)
-			if opts.accent then
-				local hue = 'var(--accent)'
-				local hsep = tonumber(opts['hue-spread'])
-				if hsep and sep and sep ~= 0 then
-					hue = string.format('calc(%s - %s)', hue, sep * hsep)
-				end
-				return hsl(hue, math.floor(100*sat), math.floor(100*fac), alpha)
-			else
-				local g = math.floor(0xFF * fac)
-				return string.format('#' .. string.rep('%02x',alpha and 4 or 3), g,g,g,alpha and math.floor(0xFF*alpha))
-			end
-		end
-		local replace = function(var,alpha,param)
-			local tonespan = opts.accent and .1 or 0
-			local tbg = opts['dark-on-light'] and 1.0 - tonespan or tonespan
-			local tfg = opts['dark-on-light'] and tonespan or 1.0 - tonespan
-			if var == 'bg' then
-				return tone(tbg,nil,nil,tonumber(alpha))
-			elseif var == 'fg' then
-				return tone(tfg,nil,nil,tonumber(alpha))
-			elseif var == 'width' then
-				return opts['width'] or '100vw'
-			elseif var == 'tone' then
-				local l, sep, sat
-				for i=1,3 do -- 🙄
-					l,sep,sat = param:match('^%('..string.rep('([^%s]*)%s*',i)..'%)$')
-					if l then break end
-				end
-				l = ss.math.lerp(tonumber(l), tbg, tfg)
-				return tone(l, tonumber(sat), tonumber(sep), tonumber(alpha))
-			end
-		end
-		css = css:gsub('@(%b[]):(%b[])', function(v,d) return opts[v:sub(2,-2)] or v:sub(2,-2) end)
-		css = css:gsub('@(%w+)/([0-9.]+)(%b())', replace)
-		css = css:gsub('@(%w+)(%b())', function(a,b) return replace(a,nil,b) end)
-		css = css:gsub('@(%w+)/([0-9.]+)', replace)
-		css = css:gsub('@(%w+)', function(a,b) return replace(a,nil,b) end)
-		return (css:gsub('%s+',' '))
-	end
-
-	local styles = {}
-	if opts.width then
-		table.insert(styles, string.format([[body {padding:0 1em;margin:auto;max-width:%s}]], opts.width))
-	end
-	if opts.accent then
-		table.insert(styles, string.format(':root {--accent:%s}', opts.accent))
-	end
-	if opts.accent or (not opts['dark-on-light']) and (not opts['fossil-uv']) then
-		stylesNeeded.accent = true
-	end
-
-
-	for k in pairs(stylesNeeded) do
-		if not stylesets[k] then ct.exns.unimpl('styleset %s not implemented (!)',  k):throw() end
-		table.insert(styles, prepcss(stylesets[k]))
-	end
-
-	local head = {}
-	local styletag = ''
-	if opts['link-css'] then
-		local css = opts['link-css']
-		if type(css) ~= 'string' then ct.exns.mode('must be a string', 'html:link-css'):throw() end
-		styletag = styletag .. tagproc.toHTML.elt('link',{rel='stylesheet',type='text/css',href=opts['link-css']})
-	end
-	if next(styles) then
-		if opts['gen-styles'] then
-			styletag = styletag .. tagproc.toHTML.tag('style',{type='text/css'},table.concat(styles))
-		end
-		table.insert(head, styletag)
-	end
-
-	if opts['fossil-uv'] then
-		return tagproc.toHTML.tag('div',{class='fossil-doc',['data-title']=doctitle},styletag .. body)
-	elseif opts.snippet then
-		return styletag .. body
-	else
-		return dr.htmlDoc(doctitle, next(head) and table.concat(head), body)
-	end
 end
+
+-- renderer engines
 
 do -- define span control sequences
 	local function formatter(sty)
 		return function(s,c)
@@ -1477,9 +643,9 @@
 			local m = {s} --TODO
 			return {
 				kind = 'math';
 				original = s;
-				spans = m;
+				spans = {s};
 				origin = c:clone();
 			};
 		end};
 		{seq = '&', parse = function(s, c)
@@ -1486,9 +652,9 @@
 			local r, t = s:match '^([^%s]+)%s*(.-)$'
 			return {
 				kind = 'deref';
 				spans = (t and t ~= "") and ct.parse_span(t, c) or {};
-				ref = r; 
+				ref = r;
 				origin = c:clone();
 			}
 		end};
 		{seq = '^', parse = function(s, c)
@@ -1579,9 +745,9 @@
 			local substr, following = delimited('[',']',str:sub(p.byte))
 			p.next.byte = following + p.byte
 			local found = false
 			for _,i in pairs(ct.spanctls) do
-				if startswith(substr, i.seq) then
+				if ss.str.begins(substr, i.seq) then
 					found = true
 					table.insert(spans, i.parse(substr:sub(1+#i.seq), ctx))
 					break
 				end