Fix review findings in the regex engine, search count and journal v2

- PCRE2: compile with the ANYCRLF newline convention and DOLLAR_ENDONLY,
  as ECMAScript reads '.' and '$'. With PCRE2's default (LF only) '.'
  matched the CR of a CRLF line, so regex replace-all deleted CRs.
- Replacement $0 is the whole match, two digits are read greedily and a
  group the pattern lacks expands to nothing, as std::regex_replace
  (libstdc++) does; these cases are now compared in the tests.
- Plain search visits overlapping matches going forward too, and counts
  them, as the backward search found them ('aa' in 'aaa' read 2/1).
- The recovery prompt's replayed content is used on 'y' only if the
  journal is unchanged since; otherwise it is replayed again.
- A version 1 journal continued after recovery is rewritten as a
  compacted version 2 journal when it needs a chunked checkpoint,
  instead of receiving records an older kte would skip. (The version is
  read through a separate descriptor: the journal fd is write-only.)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015rcVQiiWyTzoNrsvLSaAfB

Command.cc

@@ -1169,7 +1169,7 @@ search_count(const Buffer &buf, bool regex, const std::string &q, const RegexMat
 			else
 				c.reached = true;
 			++c.total;
-			p += q.size();
+			p += 1; // overlapping, as Next/Previous visit them
 		}
 		if (p != std::string_view::npos && p >= cur_off)
 			c.reached = true;
@@ -1238,7 +1238,9 @@ run_search(Editor &ed, Buffer &buf, bool regex, SearchStep step, bool incrementa
 		x = ed.SearchOrigX();
 	}
 	if (step == SearchStep::Next && have_cur) {
-		const std::size_t len = std::max<std::size_t>(ed.SearchMatchLen(), 1);
+		// Plain search visits overlapping matches ("aa" in "aaa" at 0 and 1),
+		// as the backward search does; a regex continues after its match.
+		const std::size_t len = regex ? std::max<std::size_t>(ed.SearchMatchLen(), 1) : 1;
 		x += len;
 		if (x > line_text_view(buf, y).size() && y + 1 < buf.Nrows()) {
 			++y;

Editor.cc

@@ -397,6 +397,7 @@ Editor::CancelRecoveryPrompt()
 	pending_recovery_replay_err_.clear();
 	std::string().swap(pending_recovery_content_);
 	pending_recovery_valid_bytes_  = 0;
+	pending_recovery_swap_size_    = 0;
 	pending_recovery_have_content_ = false;
 }
 
@@ -413,6 +414,7 @@ Editor::ResolveRecoveryPrompt(const bool yes)
 	std::string content      = std::move(pending_recovery_content_);
 	const bool have_content  = pending_recovery_have_content_;
 	std::uint64_t valid_bytes = pending_recovery_valid_bytes_;
+	const std::uint64_t swap_size_then = pending_recovery_swap_size_;
 	CancelRecoveryPrompt();
 
 	std::string err;
@@ -427,8 +429,13 @@ Editor::ResolveRecoveryPrompt(const bool yes)
 				SetStatus("Recovery failed: no buffer");
 				return false;
 			}
-			if (have_content) {
-				// The prompt already replayed the journal; install that.
+			std::uint64_t swap_size_now = 0;
+			try {
+				swap_size_now = std::filesystem::file_size(swp);
+			} catch (...) {
+			}
+			if (have_content && swap_size_now == swap_size_then) {
+				// The prompt already replayed the journal (unchanged since); install that.
 				b->replace_all_bytes(content);
 				std::string().swap(content);
 			} else {
@@ -607,6 +614,11 @@ Editor::process_pending_opens_()
 						pending_recovery_content_      = std::move(rec);
 						pending_recovery_valid_bytes_  = valid;
 						pending_recovery_have_content_ = true;
+						try {
+							pending_recovery_swap_size_ = std::filesystem::file_size(swp);
+						} catch (...) {
+							pending_recovery_have_content_ = false; // replay on "y"
+						}
 						StartPrompt(PromptKind::Confirm, "Recover", "");
 						SetStatus("Recover swap edits for " + req.path + "? (y/n, C-g cancel)");
 						return opened_any;

Editor.h

@@ -721,6 +721,7 @@ private:
 	// produced it: "y" installs it instead of replaying the journal again.
 	std::string pending_recovery_content_;
 	std::uint64_t pending_recovery_valid_bytes_ = 0;
+	std::uint64_t pending_recovery_swap_size_   = 0; // the journal's size then
 	bool pending_recovery_have_content_         = false;
 
 	// GUI-only state (safe no-op in terminal builds)

RegexEngine.cc

@@ -38,24 +38,20 @@ append_format(std::string &out, std::string_view fmt, std::string_view subject,
 			out.append(subject.substr(me));
 			++i;
 		} else if (n >= '0' && n <= '9') {
-			// $nn if that group exists, else $n; $0 is not a reference.
+			// As libstdc++'s match_results::format: up to two digits, read
+			// greedily; $0 is the whole match; a group the pattern does not
+			// have expands to nothing.
 			std::size_t idx = static_cast<std::size_t>(n - '0');
-			std::size_t used = 1;
-			if (i + 2 < fmt.size() && fmt[i + 2] >= '0' && fmt[i + 2] <= '9') {
-				const std::size_t two = idx * 10 + static_cast<std::size_t>(fmt[i + 2] - '0');
-				if (two >= 1 && two < ngroups) {
-					idx  = two;
-					used = 2;
-				}
-			}
-			if (idx == 0 || idx >= ngroups) {
-				out.push_back(c); // not a group reference: literal
-				continue;
+			++i;
+			if (i + 1 < fmt.size() && fmt[i + 1] >= '0' && fmt[i + 1] <= '9') {
+				idx = idx * 10 + static_cast<std::size_t>(fmt[i + 1] - '0');
+				++i;
 			}
 			std::size_t b = 0, e = 0;
-			if (group(idx, b, e))
+			if (idx == 0)
+				out.append(subject.substr(ms, me - ms));
+			else if (idx < ngroups && group(idx, b, e))
 				out.append(subject.substr(b, e - b));
-			i += used;
 		} else {
 			out.push_back(c);
 		}
@@ -121,8 +117,16 @@ Regex::Compile(std::string_view pattern, std::string &err)
 	int errcode        = 0;
 	PCRE2_SIZE erroff  = 0;
 	static const char empty = '\0';
+	// As in ECMAScript (std::regex): '.' matches neither CR nor LF, and '$'
+	// matches only at the end (PCRE2's default newline is LF alone, so '.'
+	// matched the CR of a CRLF line and replace-all deleted it).
+	pcre2_compile_context *cctx = pcre2_compile_context_create(nullptr);
+	if (cctx)
+		pcre2_set_newline(cctx, PCRE2_NEWLINE_ANYCRLF);
 	impl->code = pcre2_compile(reinterpret_cast<PCRE2_SPTR>(pattern.data() ? pattern.data() : &empty),
-	                           pattern.size(), 0, &errcode, &erroff, nullptr);
+	                           pattern.size(), PCRE2_DOLLAR_ENDONLY, &errcode, &erroff, cctx);
+	if (cctx)
+		pcre2_compile_context_free(cctx);
 	if (!impl->code) {
 		PCRE2_UCHAR msg[256];
 		pcre2_get_error_message(errcode, msg, sizeof(msg));

RegexEngine.h

@@ -11,8 +11,11 @@
  * PCRE2 additionally has lookbehind, possessive quantifiers and the like.
  *
  * Replacement strings use ECMAScript syntax with either engine, as
- * std::regex_replace reads it: $& (the match), $1..$99 (groups), $` (the
- * text since the previous match), $' (the rest of the line), $$ (a dollar).
+ * std::regex_replace (libstdc++) reads it: $& or $0 (the match), $1..$99
+ * (groups, two digits read greedily; a group the pattern lacks expands to
+ * nothing), $` (the text since the previous match), $' (the rest of the
+ * line), $$ (a dollar sign). As in ECMAScript, '.' matches neither CR nor
+ * LF and '$' matches only at the end of the line's text.
  */
 #pragma once
 

Swap.cc

@@ -845,6 +845,7 @@ SwapManager::open_ctx(JournalCtx &ctx, const std::string &path, std::string &err
 	if (st.st_size == 0) {
 		ctx.header_ok         = write_header(fd, ctx);
 		ctx.approx_size_bytes = ctx.header_ok ? 64 : 0;
+		ctx.header_version    = VERSION;
 		if (!ctx.header_ok) {
 			err = "Failed to write swap file header: " + path;
 			// Drop any partial header and close, so the next attempt starts a
@@ -856,6 +857,20 @@ SwapManager::open_ctx(JournalCtx &ctx, const std::string &path, std::string &err
 	} else {
 		ctx.header_ok         = true; // stage 1: trust existing header
 		ctx.approx_size_bytes = static_cast<std::uint64_t>(st.st_size);
+		// An existing journal (continued after recovery) may be version 1,
+		// which must not receive chunked checkpoints (see process_one).
+		// (The journal fd is write-only; read through another.)
+		std::uint8_t ver[4] = {0, 0, 0, 0};
+		ctx.header_version  = 0;
+		const int rfd       = kte::syscall::Open(path.c_str(), O_RDONLY | O_CLOEXEC, 0);
+		if (rfd >= 0) {
+			if (::pread(rfd, ver, sizeof(ver), 8) == static_cast<ssize_t>(sizeof(ver)))
+				ctx.header_version = static_cast<std::uint32_t>(ver[0]) |
+				                     (static_cast<std::uint32_t>(ver[1]) << 8) |
+				                     (static_cast<std::uint32_t>(ver[2]) << 16) |
+				                     (static_cast<std::uint32_t>(ver[3]) << 24);
+			kte::syscall::Close(rfd);
+		}
 	}
 	return ctx.header_ok;
 }
@@ -1025,6 +1040,7 @@ SwapManager::compact_to_checkpoint(JournalCtx &ctx, const RecordFrames &chkpt_re
 		(void) ::fcntl(tfd, F_SETFL, fl | O_APPEND);
 	ctx.fd             = tfd;
 	ctx.header_ok      = true;
+	ctx.header_version = VERSION;
 
 	// Best-effort: fsync parent dir to persist the rename.
 	try {
@@ -1556,8 +1572,14 @@ SwapManager::process_one(const Pending &p)
 		// For a large buffer the thresholds scale with its size, so the cost
 		// of compacting stays proportional to what was journaled since.
 		const std::uint64_t compact_at = std::max<std::uint64_t>(compact_bytes, 2 * p.chkpt.size());
-		if (p.type == SwapRecType::CHKPT && compact_bytes > 0 &&
-		    ctxp->approx_size_bytes + rec.total >= compact_at) {
+		// A chunked checkpoint may not be appended to a version 1 journal
+		// (an older kte would skip it and misapply what follows): write it
+		// as a compacted version 2 journal instead.
+		const bool chunked    = p.type == SwapRecType::CHKPT && p.chkpt.size() > kMaxRecordPayload - 5;
+		const bool v1_journal = ctxp->header_version != 0 && ctxp->header_version < 2;
+		if (p.type == SwapRecType::CHKPT &&
+		    ((chunked && v1_journal) ||
+		     (compact_bytes > 0 && ctxp->approx_size_bytes + rec.total >= compact_at))) {
 			std::string compact_err;
 			if (compact_to_checkpoint(*ctxp, rec, compact_err)) {
 				std::lock_guard<std::mutex> lg(mtx_);
@@ -1566,7 +1588,10 @@ SwapManager::process_one(const Pending &p)
 				circuit_breaker_.RecordSuccess();
 				return;
 			}
-			report_error(compact_err, p.buf); // fall back to appending
+			report_error(compact_err, p.buf);
+			if (chunked && v1_journal)
+				return; // not appended; the records around it stay valid
+			// otherwise fall back to appending
 		}
 
 		// Remember where this record starts so a partial write can be undone;

Swap.h

@@ -237,6 +237,7 @@ private:
 		bool gap{false};
 		bool gap_notified{false}; // the user was told about the current gap
 		bool chkpt_queued{false}; // a checkpoint is queued and not yet being written
+		std::uint32_t header_version{0}; // of the open journal file (0: none yet)
 		bool lockout_notified{false}; // told about the lock; kept across ResetJournal
 		std::uint64_t gap_chkpt_request_ns{0};
 		bool gap_unfixable_reported{false}; // gap on a buffer too large to checkpoint

docs/audits/claude-findings-20260923.md

@@ -558,6 +558,15 @@ before the fix (unless noted).
   1.55 s -> 0.10 s per keystroke.
 - Only one checkpoint per journal is queued at a time; whole-file edits
   in a row on a large buffer each queued a full copy of it.
+- Review of this work found, and these are fixed: with PCRE2, '.'
+  matched the CR of CRLF lines (regex replace-all deleted it) — PCRE2
+  now uses the ANYCRLF newline convention and $ matches only at the end;
+  $0, out-of-range $n and $nn in replacements now follow libstdc++;
+  plain search visits overlapping matches in both directions (the count
+  could read "2/1"); the recovery prompt replays again if the journal
+  changed while it was open; a version 1 journal continued after
+  recovery gets a chunked checkpoint only by being rewritten as
+  version 2.
 
 **Known limitations (not fixed)**
 - Without PCRE2 (std::regex builds), catastrophic regex backtracking

tests/test_audit_regressions.cc

@@ -17,6 +17,7 @@
 #include "syntax/LanguageHighlighter.h"
 
 #include <chrono>
+#include <cstring>
 #include <filesystem>
 #include <fstream>
 #include <fcntl.h>
@@ -2184,16 +2185,20 @@ TEST(Swap_DeferredBaseCrc)
 }
 
 
-// kte::Regex replacements follow std::regex_replace (ECMAScript), whichever
-// engine is built in. (References to groups the pattern does not have, like
-// $3 with two groups, are implementation-defined and left out.)
+// kte::Regex replacements follow std::regex_replace (ECMAScript as libstdc++
+// reads it), whichever engine is built in.
 TEST(RegexEngine_ReplaceMatchesStdRegex)
 {
 	const char *subjects[] = {"", "baaac", "one two  three", "a-b-c", "xyz", "aaa", "  lead", "tail  "};
 	const std::pair<const char *, const char *> cases[] = {
 		{"a*", "X"}, {"a", "[$&]"}, {"(\\w+)", "<$1>"}, {"(o)(n)?", "$2$1"}, {"-", "$`|$'"},
 		{"\\s+", "$$"}, {"^", ">"}, {"$", "<"}, {"b|", "_"}, {"\\b", "|"},
-		{"([a-z])([a-z])", "$2$1"}, {"(a)(x)?", "[$2]"}
+		{"([a-z])([a-z])", "$2$1"}, {"(a)(x)?", "[$2]"},
+#if defined(__GLIBCXX__)
+		// Read as libstdc++ reads them (libc++ differs): $0 is the match,
+		// two digits are read greedily, missing groups expand to nothing.
+		{"b", "[$0]"}, {"(b?)", "<$10>"}, {"(a)", "[$2]"}, {"(a)(b)?", "$12"},
+#endif
 	};
 	for (const char *subj: subjects) {
 		for (const auto &[pat, fmt]: cases) {
@@ -2228,3 +2233,94 @@ TEST(RegexEngine_CatastrophicPatternStops)
 	ASSERT_TRUE(h.EditorRef().Status().find("too complex") != std::string::npos);
 	ASSERT_TRUE(h.Exec(CommandId::Refresh));
 }
+
+
+// '.' does not match the CR of a CRLF line (PCRE2's default newline
+// convention let it, and regex replace-all deleted the CR).
+TEST(RegexEngine_DotDoesNotMatchCR)
+{
+	TestHarness h;
+	h.Buf().insert_text(0, 0, "abc\r\ndef\r\n");
+	regex_replace_all(h, "b.*", "X");
+	ASSERT_EQ(h.Text(), std::string("aX\r\ndef\r\n"));
+	kte::Regex rx;
+	std::string err;
+	ASSERT_TRUE(rx.Compile("c$", err));
+	std::size_t pos = 0, len = 0;
+	ASSERT_TRUE(!rx.Search("abc\r", 0, pos, len)); // '$' only at the very end
+	ASSERT_TRUE(rx.Search("abc", 0, pos, len));
+}
+
+
+// Plain search visits overlapping matches in both directions, and the count
+// agrees (Previous found the overlapping one while Next and the count
+// skipped it: "2/1").
+TEST(Search_OverlappingMatchesConsistent)
+{
+	TestHarness h;
+	Editor &ed = h.EditorRef();
+	h.Buf().insert_text(0, 0, "aaa");
+	h.Buf().SetCursor(0, 0);
+	ASSERT_TRUE(h.Exec(CommandId::FindStart));
+	ASSERT_TRUE(h.Exec(CommandId::InsertText, "aa"));
+	ASSERT_EQ(h.Buf().Curx(), (std::size_t) 0);
+	ASSERT_TRUE(ed.Status().find("1/2") != std::string::npos);
+	ASSERT_TRUE(h.Exec(CommandId::MoveRight));
+	ASSERT_EQ(h.Buf().Curx(), (std::size_t) 1);
+	ASSERT_TRUE(ed.Status().find("2/2") != std::string::npos);
+	ASSERT_TRUE(h.Exec(CommandId::MoveLeft));
+	ASSERT_EQ(h.Buf().Curx(), (std::size_t) 0);
+	ASSERT_TRUE(h.Exec(CommandId::MoveLeft)); // wraps
+	ASSERT_EQ(h.Buf().Curx(), (std::size_t) 1);
+	ASSERT_TRUE(ed.Status().find("2/2") != std::string::npos);
+	ASSERT_TRUE(h.Exec(CommandId::Refresh));
+}
+
+
+// A version 1 journal (continued after recovery) never receives chunked
+// checkpoint records, which an older kte would skip: the checkpoint is
+// written as a compacted version 2 journal instead.
+TEST(Swap_V1JournalGetsNoChunkedRecords)
+{
+	TempDir d("v1_chunked");
+	const std::string path = (d.path / "big.txt").string();
+	const std::string text = big_text();
+	{
+		std::ofstream o(path, std::ios::binary);
+		o << text;
+	}
+	Buffer b;
+	std::string err;
+	ASSERT_TRUE(b.OpenFromFile(path, err));
+	const std::string swp = kte::SwapManager::ComputeSwapPathForTests(b);
+	{
+		// A bare version 1 header (no base identity recorded).
+		std::string hdr(64, '\0');
+		std::memcpy(hdr.data(), "KTE_SWP", 8);
+		hdr[8] = 1;
+		std::ofstream o(swp, std::ios::binary | std::ios::trunc);
+		o << hdr;
+	}
+	kte::SwapManager sm;
+	sm.Attach(&b);
+	b.SetSwapRecorder(sm.RecorderFor(&b));
+	b.insert_text(0, 0, "X");
+	sm.Flush(&b);
+	sm.Checkpoint(&b);
+	sm.Flush(&b);
+	b.insert_text(0, 1, "Y");
+	sm.Flush(&b);
+	const std::string j = slurp(swp);
+	ASSERT_EQ(static_cast<unsigned char>(j[8]), 2u); // rewritten as version 2
+	const std::string copy = (d.path / "copy.swp").string();
+	{
+		std::ofstream o(copy, std::ios::binary | std::ios::trunc);
+		o << j;
+	}
+	Buffer r;
+	ASSERT_TRUE(r.OpenFromFile(path, err));
+	ASSERT_TRUE(kte::SwapManager::ReplayFile(r, copy, err));
+	ASSERT_TRUE(r.BytesForTests() == b.BytesForTests());
+	b.SetSwapRecorder(nullptr);
+	sm.Detach(&b, true);
+}