Documentation/design_www.txt     |  5 ++++-
 lib/PublicInbox/View.pm          | 33 +++++++++++++++++++++------------
 lib/PublicInbox/ViewDiff.pm      | 31 +++++++++++++++----------------
 lib/PublicInbox/WwwAtomStream.pm |  2 +-

diff --git a/Documentation/design_www.txt b/Documentation/design_www.txt
index c7d7fcbc7900183d646be7da73e7dfccf5c1ae8c..cd715b2a3f50abd10d3b644628114b0dd3fd296c 100644
--- a/Documentation/design_www.txt
+++ b/Documentation/design_www.txt
@@ -6,12 +6,15 @@ /$INBOX/?r=$GIT_COMMIT                 -> HTML only
 /$INBOX/new.atom                       -> Atom feed
 
 #### Optional, relies on Search::Xapian
-/$INBOX/$MESSAGE_ID/t/                 -> HTML content of thread
+/$INBOX/$MESSAGE_ID/t/                 -> HTML content of thread (nested)
+/$INBOX/$MESSAGE_ID/T/                 -> HTML content of thread (flat)
 	anchors:
 	#u          location of $MESSAGE_ID in URL
 	#m<SHA-1>   per-message links, where <SHA-1> is of the Message-ID
 	            of each message (stable)
 	#s<NUM>     relative numeric position of message in thread (unstable)
+	#i<...>     diffstat location for patch emails
+	#Z?<...>    per-file diff header location for patch emails
 
 /$INBOX/$MESSAGE_ID/t.atom             -> Atom feed for thread
 /$INBOX/$MESSAGE_ID/t.mbox.gz          -> gzipped mbox of thread
diff --git a/lib/PublicInbox/View.pm b/lib/PublicInbox/View.pm
index ca9b95505f6c767784d77023d8ec5fe500cf1a7e..8c8125369a69eb2b3e5961b5258a5c2056725f9a 100644
--- a/lib/PublicInbox/View.pm
+++ b/lib/PublicInbox/View.pm
@@ -37,7 +37,7 @@ 		my ($nr, undef) = @_;
 		if ($nr == 1) {
 			# $more cannot be true w/o $smsg being defined:
 			my $upfx = $more ? '../'.mid_escape($smsg->mid).'/' : '';
-			$tip . multipart_text_as_html($mime, $upfx, $ibx) .
+			$tip . multipart_text_as_html($mime, $upfx, $ctx) .
 				'</pre><hr>'
 		} elsif ($more && @$more) {
 			++$end;
@@ -90,7 +90,7 @@ 		if ($smsg) {
 			my $mime = $smsg->{mime};
 			my $upfx = '../' . mid_escape($smsg->mid) . '/';
 			_msg_html_prepare($mime->header_obj, $ctx, $more, $nr) .
-				multipart_text_as_html($mime, $upfx, $ibx) .
+				multipart_text_as_html($mime, $upfx, $ctx) .
 				'</pre><hr>'
 		} else {
 			'';
@@ -262,7 +262,7 @@ 	$rv .= "\n";
 
 	# scan through all parts, looking for displayable text
 	my $ibx = $ctx->{-inbox};
-	msg_iter($mime, sub { $rv .= add_text_body($mhref, $ibx, $_[0]) });
+	msg_iter($mime, sub { $rv .= add_text_body($mhref, $ctx, $_[0]) });
 
 	# add the footer
 	$rv .= "\n<a\nhref=#$id_m\nid=e$id>^</a> ".
@@ -490,11 +490,11 @@ 	});
 }
 
 sub multipart_text_as_html {
-	my ($mime, $upfx, $ibx) = @_;
+	my ($mime, $upfx, $ctx) = @_;
 	my $rv = "";
 
 	# scan through all parts, looking for displayable text
-	msg_iter($mime, sub { $rv .= add_text_body($upfx, $ibx, $_[0]) });
+	msg_iter($mime, sub { $rv .= add_text_body($upfx, $ctx, $_[0]) });
 	$rv;
 }
 
@@ -547,10 +547,11 @@ 	$ret .= "</a>\n";
 }
 
 sub add_text_body {
-	my ($upfx, $ibx, $p) = @_;
+	my ($upfx, $ctx, $p) = @_;
+	my $ibx = $ctx->{-inbox};
 	my $obfs_ibx = $ibx->{obfuscate} ? $ibx : undef;
 	# $p - from msg_iter: [ Email::MIME, depth, @idx ]
-	my ($part, $depth) = @$p; # attachment @idx is unused
+	my ($part, $depth, @idx) = @$p;
 	my $ct = $part->content_type || 'text/plain';
 	my $fn = $part->filename;
 	my ($s, $err) = msg_part_text($part, $ct);
@@ -561,9 +562,16 @@ 	# makes no difference to browsers, and don't screw up filename
 	# link generation in diffs with the extra '%0D'
 	$s =~ s/\r\n/\n/sg;
 
-	my ($diff, $spfx);
+	# always support diff-highlighting, but we can't linkify hunk
+	# headers for solver unless some coderepo are configured:
+	my $diff;
 	if ($s =~ /^(?:diff|---|\+{3}) /ms) {
-		$diff = [];
+		# diffstat anchors do not link across attachments or messages:
+		$idx[0] = $upfx . $idx[0] if $upfx ne '';
+		$ctx->{-apfx} = join('/', @idx);
+		$ctx->{-anchors} = {}; # attr => filename
+		$ctx->{-diff} = $diff = [];
+		my $spfx;
 		if ($ibx->{-repo_objs}) {
 			my $n_slash = $upfx =~ tr!/!/!;
 			if ($n_slash == 0) {
@@ -574,6 +582,7 @@ 			} else { # nslash == 2
 				$spfx = '../../';
 			}
 		}
+		$ctx->{-spfx} = $spfx;
 	};
 
 	my @lines = split(/^/m, $s);
@@ -598,18 +607,18 @@ 				$l->linkify_1($cur);
 				$s .= $l->linkify_2(ascii_html($cur));
 			}
 		} else {
-			flush_diff(\$s, $spfx, $l, $diff) if $diff && @$diff;
+			flush_diff(\$s, $ctx, $l) if $diff && @$diff;
 			push @quot, $cur;
 		}
 	}
 
 	if (@quot) { # ugh, top posted
 		flush_quote(\$s, $l, \@quot);
-		flush_diff(\$s, $spfx, $l, $diff) if $diff && @$diff;
+		flush_diff(\$s, $ctx, $l) if $diff && @$diff;
 		obfuscate_addrs($obfs_ibx, $s) if $obfs_ibx;
 		$s;
 	} else {
-		flush_diff(\$s, $spfx, $l, $diff) if $diff && @$diff;
+		flush_diff(\$s, $ctx, $l) if $diff && @$diff;
 		obfuscate_addrs($obfs_ibx, $s) if $obfs_ibx;
 		if ($s =~ /\n\z/s) { # common, last line ends with a newline
 			$s;
diff --git a/lib/PublicInbox/ViewDiff.pm b/lib/PublicInbox/ViewDiff.pm
index 38cb5a18d711b980b87b5eafea55f973f11e2a47..2074e12fffbd01a5deb6ffd955849e7aaafd185d 100644
--- a/lib/PublicInbox/ViewDiff.pm
+++ b/lib/PublicInbox/ViewDiff.pm
@@ -76,10 +76,10 @@ 	$$dst .= qq(<span\nclass="$class">);
 }
 
 sub anchor0 ($$$$$) {
-	my ($dst, $anchors, $linkify, $fn, $rest) = @_;
-	if (my $attr = to_attr($fn)) {
-		$anchors->{$attr} = 1;
-		$$dst .= " <a\nhref=#$attr>" .
+	my ($dst, $ctx, $linkify, $fn, $rest) = @_;
+	if (my $attr = to_attr($ctx->{-apfx}.$fn)) {
+		$ctx->{-anchors}->{$attr} = 1;
+		$$dst .= " <a\nid=i$attr\nhref=#$attr>" .
 			ascii_html($fn) . '</a>'.
 			to_html($linkify, $rest);
 		return 1;
@@ -88,33 +88,33 @@ 	undef;
 }
 
 sub anchor1 ($$$$$) {
-	my ($dst, $anchors, $linkify, $pb, $s) = @_;
-	my $attr = to_attr($pb) or return;
+	my ($dst, $ctx, $linkify, $pb, $s) = @_;
+	my $attr = to_attr($ctx->{-apfx}.$pb) or return;
 	my $line = to_html($linkify, $s);
 
-	if (delete $anchors->{$attr} && $line =~ s/^diff //) {
-		$$dst .= "<a\nhref=#ds\nid=$attr>diff</a> ".$line;
+	if (delete $ctx->{-anchors}->{$attr} && $line =~ s/^diff //) {
+		$$dst .= "<a\nhref=#i$attr\nid=$attr>diff</a> ".$line;
 		return 1;
 	}
 	undef
 }
 
-sub flush_diff ($$$$) {
-	my ($dst, $spfx, $linkify, $diff) = @_;
+sub flush_diff ($$$) {
+	my ($dst, $ctx, $linkify) = @_;
+	my $diff = $ctx->{-diff};
+	my $spfx = $ctx->{-spfx};
 	my $state = DSTATE_INIT;
 	my $dctx = { Q => '' }; # {}, keys: oid_a, oid_b, path_a, path_b
-	my $anchors = {}; # attr => filename
 
 	foreach my $s (@$diff) {
 		if ($s =~ /^---$/) {
 			to_state($dst, $state, DSTATE_STAT);
-			$$dst .= "<span\nid=ds>" . $s . '</span>';
+			$$dst .= $s;
 		} elsif ($s =~ /^ /) {
 			# works for common cases, but not weird/long filenames
 			if ($state == DSTATE_STAT &&
 					$s =~ /^ (\S+)(\s+\|.*\z)/s) {
-				anchor0($dst, $anchors, $linkify, $1, $2)
-					and next;
+				anchor0($dst, $ctx, $linkify, $1, $2) and next;
 			} elsif ($state2class[$state]) {
 				to_state($dst, $state, DSTATE_CTX);
 			}
@@ -136,8 +136,7 @@ 				if ($pa ne $pb) {
 					$dctx->{Q} .=
 					     "&a=".uri_escape_utf8($pa, UNSAFE);
 				}
-				anchor1($dst, $anchors, $linkify, $pb, $s)
-					and next;
+				anchor1($dst, $ctx, $linkify, $pb, $s) and next;
 			}
 			$$dst .= to_html($linkify, $s);
 		} elsif ($s =~ s/^(index $OID_NULL\.\.)($OID_BLOB)\b//o) {
diff --git a/lib/PublicInbox/WwwAtomStream.pm b/lib/PublicInbox/WwwAtomStream.pm
index 712c3dc88e34a3c210d6f74ac2ebd013c2863f91..6d3a93649b29162a42d6892ced17ab256a366425 100644
--- a/lib/PublicInbox/WwwAtomStream.pm
+++ b/lib/PublicInbox/WwwAtomStream.pm
@@ -137,7 +137,7 @@ 		"<id>$uuid</id>$irt" .
 		qq{<content\ntype="xhtml">} .
 		qq{<div\nxmlns="http://www.w3.org/1999/xhtml">} .
 		qq(<pre\nstyle="white-space:pre-wrap">) .
-		PublicInbox::View::multipart_text_as_html($mime, $href) .
+		PublicInbox::View::multipart_text_as_html($mime, $href, $ctx) .
 		'</pre></div></content></entry>';
 }