From c5042b71d35d0d72f501d8be4e9ea95b1534ad8a Mon Sep 17 00:00:00 2001
From: Terry Carr <terry@terrycarr.dev>
Date: Sat, 10 Oct 2026 21:56:21 +0100
Subject: [PATCH] fix: improve hashtag span validation and enhance test
 coverage for edge cases

---
 src/ui-touch/ChatHashtag.h | 11 +++++++++--
 test/test_utf8_text.cpp    | 25 +++++++++++++++++++++++--
 2 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/src/ui-touch/ChatHashtag.h b/src/ui-touch/ChatHashtag.h
index 7a5769f..c46c20f 100644
--- a/src/ui-touch/ChatHashtag.h
+++ b/src/ui-touch/ChatHashtag.h
@@ -29,12 +29,18 @@ namespace ChatHashtag
     inline bool isHexColor(const char *text, int start, int end)
     {
         const int length = end - start;
-        if (length != 3 && length != 4 && length != 6 && length != 8)
+        if (length != 6 && length != 8)
             return false;
+        bool colorLike = false;
         for (int offset = start; offset < end; ++offset)
+        {
             if (!isxdigit((unsigned char)text[offset]))
                 return false;
-        return true;
+            if (isdigit((unsigned char)text[offset]) ||
+                (text[offset] >= 'A' && text[offset] <= 'F'))
+                colorLike = true;
+        }
+        return colorLike;
     }
 
     inline bool span(const char *text, int from, int *start, int *end)
@@ -81,6 +87,7 @@ namespace ChatHashtag
             }
             if (finish == offset + 1 || finish - offset >= 32 ||
                 isdigit((unsigned char)text[offset + 1]) ||
+                text[offset + 1] == '_' || text[offset + 1] == '-' ||
                 isHexColor(text, offset + 1, finish))
                 continue;
             *start = offset;
diff --git a/test/test_utf8_text.cpp b/test/test_utf8_text.cpp
index 512a781..8150f83 100644
--- a/test/test_utf8_text.cpp
+++ b/test/test_utf8_text.cpp
@@ -26,6 +26,19 @@ int main() {
   assert(!ChatHashtag::span("#caf\xC3", 0, &start, &end));
   assert(!ChatHashtag::span("#1", 0, &start, &end));
   assert(!ChatHashtag::span("#1channel", 0, &start, &end));
+  assert(!ChatHashtag::span("#_", 0, &start, &end));
+  assert(!ChatHashtag::span("#-", 0, &start, &end));
+  assert(!ChatHashtag::span("#___", 0, &start, &end));
+  assert(!ChatHashtag::span("#---", 0, &start, &end));
+  assert(!ChatHashtag::span("#_-_", 0, &start, &end));
+  assert(!ChatHashtag::span("#_42", 0, &start, &end));
+  assert(!ChatHashtag::span("#-42", 0, &start, &end));
+  assert(!ChatHashtag::span("#_mesh", 0, &start, &end));
+  assert(!ChatHashtag::span("#-mesh", 0, &start, &end));
+  const std::string separators_then_tag = "#_ #- #_-_ #_42 #-42 #mesh";
+  assert(ChatHashtag::span(separators_then_tag.c_str(), 0, &start, &end));
+  assert(separators_then_tag.substr(start, end - start) == "#mesh");
+  assert(!ChatHashtag::span(separators_then_tag.c_str(), end, &start, &end));
   assert(ChatHashtag::span("#channel1", 0, &start, &end));
   const std::string trailing_hyphen = "#mesh-";
   assert(ChatHashtag::span(trailing_hyphen.c_str(), 0, &start, &end));
@@ -39,11 +52,19 @@ int main() {
   const std::string underscored = "#mesh_channel";
   assert(ChatHashtag::span(underscored.c_str(), 0, &start, &end));
   assert(underscored.substr(start, end - start) == "#mesh_channel");
-  assert(!ChatHashtag::span("#FFF", 0, &start, &end));
-  assert(!ChatHashtag::span("#FFFF", 0, &start, &end));
+  assert(ChatHashtag::span("#FFF", 0, &start, &end));
+  assert(ChatHashtag::span("#FFFF", 0, &start, &end));
+  assert(ChatHashtag::span("#beef", 0, &start, &end));
+  assert(ChatHashtag::span("#cafe", 0, &start, &end));
+  assert(ChatHashtag::span("#abcdef", 0, &start, &end));
+  assert(ChatHashtag::span("#deadbeef", 0, &start, &end));
   assert(!ChatHashtag::span("#FFFFFF", 0, &start, &end));
   assert(!ChatHashtag::span("#FF0000", 0, &start, &end));
   assert(!ChatHashtag::span("#FFFFFFFF", 0, &start, &end));
+  assert(!ChatHashtag::span("#abcDef", 0, &start, &end));
+  assert(!ChatHashtag::span("#ff0000", 0, &start, &end));
+  assert(!ChatHashtag::span("#abcdef12", 0, &start, &end));
+  assert(ChatHashtag::span("#mesh12", 0, &start, &end));
   assert(ChatHashtag::span("#cable", 0, &start, &end));
   std::string long_tag = "#";
   for (int count = 0; count < 15; ++count)