@@ -1,8 +1,8 @@
 -- [ʞ] cortav.lua
 --  ~ lexi hale <lexi@hale.su>
 --  © AGPLv3
---  ? renderer
+--  ? reference implementation of the cortav document language
 
 local ct = { render = {} }
 
 local function hexdump(s)
@@ -69,8 +69,18 @@
 	else
 		return tostring(o)
 	end
 end
+
+local function
+lerp(t, a, b)
+	return (1-t)*a + (t*b)
+end
+
+local function
+startswith(str, pfx)
+	return string.sub(str, 1, #pfx) == pfx
+end
 
 local function declare(c)
 	local cls = setmetatable({
 		__name = c.ident;
@@ -176,8 +186,9 @@
 	cli = ct.exnkind 'command line parse error';
 	mode = ct.exnkind('bad mode', function(msg, ...)
 		return string.format("mode “%s” "..msg, ...)
 	end);
+	unimpl = ct.exnkind 'feature not implemented';
 }
 
 ct.ctx = declare {
 	mk = function(src) return {src = src} end;
@@ -198,8 +209,12 @@
 	fns = {
 		fail = function(self, msg, ...)
 			ct.exns.tx(msg, self.src.file, self.line or 0, ...):throw()
 		end;
+		insert = function(self, block)
+			block.origin = self:clone()
+			table.insert(self.sec.blocks,block)
+		end;
 		ref = function(self,id)
 			if not id:find'%.' then
 				local rid = self.sec.refs[id]
 				if self.sec.refs[id] then
@@ -240,14 +255,59 @@
 			if id then self.sections[id] = o end
 			table.insert(self.secorder, o)
 			return o
 		end;
+		context_var = function(self, var, ctx, test)
+			local fail = function(...)
+				if test then return false end
+				ctx:fail(...)
+			end
+			if startswith(var, 'cortav.') then
+				local v = var:sub(8)
+				if v == 'page' then
+					if ctx.page then return tostring(ctx.page)
+						else return '(unpaged)' end
+				elseif v == 'renderer' then
+					if not self.stage then
+						return fail 'document is not being rendererd'
+					end
+					return self.stage.format
+				elseif v == 'datetime' then
+					return os.date()
+				elseif v == 'time' then
+					return os.date '%H:%M:%S'
+				elseif v == 'date' then
+					return os.date '%A %d %B %Y'
+				elseif v == 'id' then
+					return 'cortav.lua (reference implementation)'
+				elseif v == 'file' then
+					return self.src.file
+				else
+					return fail('unimplemented predefined variable %s', var)
+				end
+			elseif startswith(var, 'env.') then
+				local v = var:sub(5)
+				local val = os.getenv(v)
+				if not val then
+					return fail('undefined environment variable %s', v)
+				end
+			elseif self.stage.kind == 'render' and startswith(var, self.stage.format..'.') then
+				-- TODO query the renderer somehow
+				return fail('renderer %s does not implement variable %s', self.stage.format, var)
+			elseif self.vars[var] then
+				return self.vars[var]
+			else
+				if test then return false end
+				return '' -- is this desirable behavior?
+			end
+		end;
 	};
 	mk = function() return {
 		sections = {};
 		secorder = {};
 		embed = {};
 		meta = {};
+		vars = {};
 	} end;
 }
 
 local function map(fn, lst)
@@ -269,8 +329,9 @@
 	end
 end
 
 function ct.render.html(doc, opts)
+	local doctitle = opts['title']
 	local f = string.format
 	local ids = {}
 	local canonicalID = {}
 	local function getSafeID(obj)
@@ -310,12 +371,27 @@
 		python = { color = 0xcdd6ff };
 	}
 
 	local stylesets = {
+		accent = [[
+			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,h2,h3,h4,h5,h6 {
+				color: @tone(2);
+				border-bottom: 1px solid @tone(0.7);
+			}
+		]];
 		code = [[
 			code {
-				background: #000;
-				color: #fff;
+				background: @fg;
+				color: @bg;
 				font-family: monospace;
 				font-size: 90%;
 				padding: 3px 5px;
 			}
@@ -326,14 +402,15 @@
 		editors_markup = [[]];
 		block_code_listing = [[
 			section > figure.listing {
 				font-family: monospace;
-				background: #000;
-				color: #fff;
+				background: @tone(0.05);
+				color: @fg;
 				padding: 0;
 				margin: 0.3em 0;
 				counter-reset: line-number;
 				position: relative;
+				border: 1px solid @fg;
 			}
 			section > figure.listing>div {
 				white-space: pre-wrap;
 				counter-increment: line-number;
@@ -344,27 +421,27 @@
 				width: 1.0em;
 				padding: 0.2em 0.4em;
 				text-align: right;
 				display: inline-block;
-				background-color: #333;
-				border-right: 1px solid #fff;
+				background-color: @tone(0.2);
+				border-right: 1px solid @fg;
 				content: counter(line-number);
 				margin-right: 0.3em;
 			}
 			section > figure.listing>hr::before {
-				color: #333;
+				color: transparent;
 				padding-top: 0;
 				padding-bottom: 0;
 			}
 			section > figure.listing>div::before {
-				color: #fff;
+				color: @fg;
 			}
 			section > figure.listing>div:last-child::before {
 				padding-bottom: 0.5em;
 			}
 			section > figure.listing>figcaption:first-child {
 				border: none;
-				border-bottom: 1px solid #fff;
+				border-bottom: 1px solid @fg;
 			}
 			section > figure.listing>figcaption::after {
 				display: block;
 				float: right;
@@ -374,12 +451,12 @@
 				padding-top: 0.3em;
 			}
 			section > figure.listing>figcaption {
 				font-family: sans-serif;
-				font-weight: bold;
-				font-size: 130%;
+				font-size: 120%;
 				padding: 0.2em 0.4em;
 				border: none;
+				color: @tone(2);
 			}
 			section > figure.listing > hr {
 				border: none;
 				margin: 0;
@@ -416,31 +493,60 @@
 			end
 			return table.concat(text)
 		end
 
-		function span_renderers.format(sp)
+		function span_renderers.format(sp,...)
 			local tags = { strong = 'strong', emph = 'em', strike = 'del', insert = 'ins', literal = 'code' }
 			if sp.style == 'literal' and not opts['fossil-uv'] then
 				stylesNeeded.code = true
 			end
 			if sp.style == 'del' or sp.style == 'ins' then
 				stylesNeeded.editors_markup = true
 			end
-			return tag(tags[sp.style],nil,htmlSpan(sp.spans))
+			return tag(tags[sp.style],nil,htmlSpan(sp.spans,...))
 		end
 
-		function span_renderers.term(t,b)
+		function span_renderers.term(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
 				b.origin:fail('%s is an object, not a reference', t.ref)
 			end
 			stylesNeeded.abbr = true
-			return tag('abbr',{title=r},next(t.spans) and htmlSpan(t.spans) or name)
+			return tag('abbr',{title=r},next(t.spans) and htmlSpan(t.spans,b,s) or name)
 		end
 
-		function span_renderers.link(sp,b)
+		function span_renderers.macro(m,b,s)
+			local r = b.origin:ref(m.macro)
+			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.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: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.link(sp,b,s)
 			local href
 			if b.origin.doc.sections[sp.ref] then
 				href = '#' .. sp.ref
 			else
@@ -450,9 +556,9 @@
 						href = '#' .. getSafeID(r)
 					else href = r end
 				end
 			end
-			return tag('a',{href=href},next(sp.spans) and htmlSpan(sp.spans) or href)
+			return tag('a',{href=href},next(sp.spans) and htmlSpan(sp.spans,b,s) or href)
 		end
 		return {
 			span_renderers = span_renderers;
 			htmlSpan = htmlSpan;
@@ -489,8 +595,17 @@
 
 		local block_renderers = {
 			paragraph = function(b,s)
 				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
 					local h = math.min(6,math.max(1,b.captions.depth))
@@ -526,9 +641,9 @@
 				end, b.lines)
 				if b.title then
 					table.insert(nodes,1,tag('figcaption',nil,sr.htmlSpan(b.title)))
 				end
-				langsused[b.lang] = true
+				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;
 			['break'] = function() --[[nop]] end;
 		}
@@ -557,9 +672,8 @@
 	local tag = function(t,attrs,body)
 		return f('%s%s</%s>', elt(t,attrs), body, t)
 	end
 
-	local doctitle
 	local ir = {}
 	local toc
 	local dr = getRenderers(tag,elt,table.concat) -- default renderers
 	local plainr = getRenderers(function(t,a,v) return v  end,
@@ -685,12 +799,74 @@
 			[[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 == '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 = lerp(tonumber(l), tbg, tfg)
+				return tone(l, tonumber(sat), tonumber(sep), tonumber(alpha))
+			end
+		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']) then
+		stylesNeeded.accent = true
+	end
+
+
 	for k in pairs(stylesNeeded) do
-		table.insert(styles, (stylesets[k]:gsub('%s+',' ')))
+		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 = ''
@@ -714,13 +890,8 @@
 		return dr.htmlDoc(doctitle, next(head) and table.concat(head), body)
 	end
 end
 
-local function
-startswith(str, pfx)
-	return string.sub(str, 1, #pfx) == pfx
-end
-
 local function eachcode(str, ascode)
 	local pos = {
 		code = 1;
 		byte = 1;
@@ -743,52 +914,20 @@
 		return thischar, lastpos
 	end
 end
 
-local function formatter(sty)
-	return function(s,c)
-		return {
-			kind = 'format';
-			style = sty;
-			spans = ct.parse_span(s, c);
-			origin = c:clone();
-		}
-	end
-end
-ct.spanctls = {
-	{seq = '$', parse = formatter 'literal'};
-	{seq = '!', parse = formatter 'emph'};
-	{seq = '*', parse = formatter 'strong'};
-	{seq = '\\', parse = function(s, c) -- raw
-		return s
-	end};
-	{seq = '$\\', parse = function(s, c) -- raw
-		return {
-			kind = 'format';
-			style = 'literal';
-			spans = {s};
-			origin = c:clone();
-		}
-	end};
-	{seq = '&', parse = function(s, c)
-		local r, t = s:match '^([^%s]+)%s*(.-)$'
-		return {
-			kind = 'term';
-			spans = (t and t ~= "") and ct.parse_span(t, c) or {};
-			ref = r; 
-			origin = c:clone();
-		}
-	end};
-	{seq = '^', parse = function(s, c)
-		local fn, t = s:match '^([^%s]+)%s*(.-)$'
-		return {
-			kind = 'footnote';
-			spans = (t and t~='') and ct.parse_span(t, c) or {};
-			ref = fn;
-			origin = c:clone();
-		}
-	end};
-	{seq = '>', parse = function(s, c)
+do -- define span control sequences
+	local function formatter(sty)
+		return function(s,c)
+			return {
+				kind = 'format';
+				style = sty;
+				spans = ct.parse_span(s, c);
+				origin = c:clone();
+			}
+		end
+	end
+	local function insert_link(s, c)
 		local to, t = s:match '^([^%s]+)%s*(.-)$'
 		if not to then c:fail('invalid link syntax >%s', s) end
 		if t == "" then t = nil end
 		return {
@@ -796,10 +935,61 @@
 			spans = (t and t~='') and ct.parse_span(t, c) or {};
 			ref = to;
 			origin = c:clone();
 		}
-	end};
-}
+	end
+	local function insert_var_ref(raw)
+		return function(s, c)
+			local pos = tonumber(s)
+			return {
+				kind = 'var';
+				pos = pos;
+				raw = raw;
+				var = not pos and s or nil;
+				origin = c:clone();
+			}
+		end
+	end
+	ct.spanctls = {
+		{seq = '$', parse = formatter 'literal'};
+		{seq = '!', parse = formatter 'emph'};
+		{seq = '*', parse = formatter 'strong'};
+		{seq = '\\', parse = function(s, c) -- raw
+			return s
+		end};
+		{seq = '$\\', parse = function(s, c) -- raw
+			return {
+				kind = 'format';
+				style = 'literal';
+				spans = {s};
+				origin = c:clone();
+			}
+		end};
+		{seq = '&', parse = function(s, c)
+			local r, t = s:match '^([^%s]+)%s*(.-)$'
+			return {
+				kind = 'term';
+				spans = (t and t ~= "") and ct.parse_span(t, c) or {};
+				ref = r; 
+				origin = c:clone();
+			}
+		end};
+		{seq = '^', parse = function(s, c)
+			local fn, t = s:match '^([^%s]+)%s*(.-)$'
+			return {
+				kind = 'footnote';
+				spans = (t and t~='') and ct.parse_span(t, c) or {};
+				ref = fn;
+				origin = c:clone();
+			}
+		end};
+		{seq = '>', parse = insert_link};
+		{seq = '→', parse = insert_link};
+		{seq = '🔗', parse = insert_link};
+		{seq = '##', parse = insert_var_ref(true)};
+		{seq = '#', parse = insert_var_ref(false)};
+	}
+end
 
 function ct.parse_span(str,ctx)
 	local function delimited(start, stop, s)
 		local depth = 0
@@ -819,9 +1009,9 @@
 				end
 			end
 		end
 
-		ctx:fail('%s expected before end of line', stop)
+		ctx:fail('[%s] expected before end of line', stop)
 	end
 	local buf = ""
 	local spans = {}
 	local function flush()
@@ -836,8 +1026,40 @@
 			skip = false
 			buf = buf .. c
 		elseif c == '\\' then
 			skip = true
+		elseif c == '{' then
+			flush()
+			local substr, following = delimited('{','}',str:sub(p.byte))
+			local splitstart, splitstop = substr:find'%s+'
+			local id, argstr
+			if splitstart then
+				id, argstr = substr:sub(1,splitstart-1), substr:sub(splitstop+1)
+			else
+				id, argstr = substr, ''
+			end
+			local o = {
+				kind = 'macro';
+				macro = id;
+				args = {};
+				origin = ctx:clone();
+			}
+
+			do local start = 1
+				local i = 1
+				while i <= #argstr do
+					while i<=#argstr and (argstr:sub(i,i) ~= '|' or argstr:sub(i-1,i) == '\\|') do
+						i = i + 1
+					end
+					local arg = argstr:sub(start, i == #argstr and i or i-1)
+					start = i+1
+					table.insert(o.args, arg)
+					i = i + 1
+				end
+			end
+
+			p.next.byte = p.next.byte + following - 1
+			table.insert(spans,o)
 		elseif c == '[' then
 			flush()
 			local substr, following = delimited('[',']',str:sub(p.byte))
 			p.next.byte = following + p.byte
@@ -945,24 +1167,49 @@
 }
 
 local function insert_table_row(l,c)
 	local row = {}
-	for kind, a1, text, a2 in l:gmatch '([+|])(:?)%s*([^:+|]*)%s*(:?)' do
-		local header = kind == '+'
-		local align
-		if     a1 == ':' and a2 ~= ':' then
-			align = 'left'
-		elseif a1 == ':' and a2 == ':' then
-			align = 'center'
-		elseif a1 ~= ':' and a2 == ':' then
-			align = 'right'
-		end
-		text = text:match '^%s*(.-)%s*$'
-		table.insert(row, {
-			spans = ct.parse_span(text, c);
-			align = align;
-			header = header;
-		})
+	local buf
+	local flush = function()
+		if buf then table.insert(row, buf) end
+		buf = { str = '' }
+	end
+	for c,p in eachcode(l) do
+		if c == '|' or c == '+' and (p.code == 1 or l:sub(p.byte-1,p.byte-1)~='\\') then
+			flush()
+			buf.header = c == '+'
+		elseif c == ':' then
+			local lst = l:sub(p.byte-#c,p.byte-#c)
+			local nxt = l:sub(p.next.byte,p.next.byte)
+			if lst == '|' or lst == '+' and l:sub(p.byte-2,p.byte-2) ~= '\\' then
+				buf.align = 'left'
+			elseif nxt == '|' or nxt == '|' then
+				if buf.align == 'left' then
+					buf.align = 'center'
+				else
+					buf.align = 'right'
+				end
+			else
+				buf.str = buf.str .. c
+			end
+		elseif c:match '%s' then
+			if buf.str ~= '' then buf.str = buf.str .. c end
+		elseif c == '\\' then
+			local nxt = l:sub(p.next.byte,p.next.byte)
+			if nxt == '|' or nxt == '+' or nxt == ':' then
+				buf.str = buf.str .. nxt
+				p.next.byte = p.next.byte + #nxt
+				p.next.code = p.next.code + 1
+			else
+				buf.str = buf.str .. c
+			end
+		else
+			buf.str = buf.str .. c
+		end
+	end
+	if buf.str ~= '' then flush() end 
+	for _,v in pairs(row) do
+		v.spans = ct.parse_span(v.str, c)
 	end
 	if #c.sec.blocks > 1 and c.sec.blocks[#c.sec.blocks].kind == 'table' then
 		local tbl = c.sec.blocks[#c.sec.blocks]
 		table.insert(tbl.rows, row)
@@ -977,8 +1224,9 @@
 
 ct.ctlseqs = {
 	{seq = '.', fn = insert_paragraph};
 	{seq = '¶', fn = insert_paragraph};
+	{seq = '❡', fn = insert_paragraph};
 	{seq = '#', fn = insert_section};
 	{seq = '§', fn = insert_section};
 	{seq = '+', fn = insert_table_row};
 	{seq = '|', fn = insert_table_row};
@@ -1008,16 +1256,24 @@
 			for w,pos in cmdline:gmatch '([^%s]+)()' do
 				table.insert(wds, w)
 				i = i - 1
 				if i == 0 then
-					return table.unpack(wds), cmdline:sub(pos)
+					table.insert(wds,cmdline:sub(pos))
+					return table.unpack(wds)
 				end
 			end
 		end
 
 		local cmd, rest = words(1)
 		if ct.directives[cmd] then
 			ct.directives[cmd](words,c)
+		elseif cmd == c.doc.stage.mode['render:format'] then
+			-- this is a directive for the renderer; insert it into the tree as is
+			c:insert {
+				kind = 'directive';
+				critical = crit == '!';
+				words = words;
+			}
 		elseif crit == '!' then
 			c:fail('critical directive %s not supported',cmd)
 		end
 	end;};
@@ -1033,9 +1289,9 @@
 		if l:match '^~~~%s*$' then -- no args
 		elseif l:match '^~~~.*~~~%s*$' then -- CT style
 			local s = l:match '^~~~%s*(.-)%s*~~~%s*$'
 			lang, s = extract('%b[]', s)
-			lang = lang:sub(2,-2)
+			if lang then lang = lang:sub(2,-2) end
 			id, title = extract('#[^%s]+', s)
 			if id then id = id:sub(2) end
 		elseif l:match '^~~~' then -- MD shorthand style
 			lang = l:match '^~~~%s*(.-)%s*$'
@@ -1070,9 +1326,9 @@
 	end)};
 	{fn = insert_paragraph};
 }
 
-function ct.parse(file, src)
+function ct.parse(file, src, mode)
 	local function
 	is_whitespace(cp)
 		return cp == 0x20
 	end
@@ -1079,8 +1335,13 @@
 
 	local ctx = ct.ctx.mk(src)
 	ctx.line = 0
 	ctx.doc = ct.doc.mk()
+	ctx.doc.src = src
+	ctx.doc.stage = {
+		kind = 'parse';
+		mode = mode;
+	}
 	ctx.sec = ctx.doc:mksec() -- toplevel section
 	ctx.sec.origin = ctx:clone()
 
 	for full_line in file:lines() do ctx.line = ctx.line + 1
@@ -1156,9 +1417,9 @@
 	return new
 end
 
 local function main(input, output, log, mode, vars)
-	local doc = ct.parse(input.stream, input.src)
+	local doc = ct.parse(input.stream, input.src, mode)
 	input.stream:close()
 	if mode['parse:show-tree'] then
 		log:write(dump(doc))
 	end
@@ -1165,19 +1426,31 @@
 
 	if not mode['render:format'] then
 		error 'what output format should i translate the input to?'
 	end
+	if mode['render:format'] == 'none' then return 0 end
 	if not ct.render[mode['render:format']] then
-		error(string.format('output format “%s” unsupported', mode['render:format']))
+		ct.exns.unimpl('output format “%s” unsupported', mode['render:format']):throw()
 	end
 	
 	local render_opts = kmap(function(k,v)
 		return k:sub(2+#mode['render:format'])
 	end, kfilter(mode, function(m)
 		return startswith(m, mode['render:format']..':')
 	end))
+
+	doc.vars = vars
+	
+	-- this is kind of gross but the context object belongs to the parser,
+	-- not the renderer, so that's not a suitable place for this information
+	doc.stage = {
+		kind = 'render';
+		format = mode['render:format'];
+		mode = mode;
+	}
 
 	output:write(ct.render[mode['render:format']](doc, render_opts))
+	return 0
 end
 
 local inp,outp,log = io.stdin, io.stdout, io.stderr
 
@@ -1230,9 +1503,12 @@
 				ct.exns.io('could not open log file for writing', 'open',file):throw()
 			end
 		end;
 		define = function(key,value)
-			-- set context key
+			if startswith(key, 'cortav.') or startswith(key, 'env.') then
+				ct.exns.cli 'cannot define variable in restricted namespace':throw()
+			end
+			vars[key] = value
 		end;
 		mode = function(key,value) mode[checkmodekey(key)] = value end;
 		['mode-set'] = function(key) mode[checkmodekey(key)] = true end;
 		['mode-clear'] = function(key) mode[checkmodekey(key)] = false end;
@@ -1290,15 +1566,18 @@
 		input.stream = file
 		input.src.file = args[1]
 	end
 
-	main(input, outp, log, mode, vars)
+	return main(input, outp, log, mode, vars)
 end
 
--- local ok, e = pcall(entry_cli)
-local ok, e = true, entry_cli()
+local ok, e = pcall(entry_cli)
+-- local ok, e = true, entry_cli()
 if not ok then
 	local str = 'translation failure'
+	if ct.exn.is(e) then
+		str = e.kind.desc
+	end
 	local color = false
 	if log:seek() == nil then
 		-- this is not a very reliable heuristic for detecting
 		-- attachment to a tty but it's better than nothing
@@ -1311,7 +1590,8 @@
 	end
 	if color then
 		str = string.format('\27[1;31m%s\27[m', str)
 	end
-	log:write(string.format('[%s] %s\n\t%s\n', os.date(), str, e))
+	log:write(string.format('%s: %s\n', str, e))
 	os.exit(1)
 end
+os.exit(e)