4 files changed, 39 insertions, 0 deletions

diff --git a/src/nvim/api/extmark.c b/src/nvim/api/extmark.c
index 1f0e867162..27a4b7854f 100644
--- a/src/nvim/api/extmark.c
+++ b/src/nvim/api/extmark.c
@@ -481,6 +481,8 @@ Array nvim_buf_get_extmarks(Buffer buffer, Integer ns_id, Object start, Object e
 ///                   by a UI. When set, the UI will receive win_extmark events.
 ///                   Note: the mark is positioned by virt_text attributes. Can be
 ///                   used together with virt_text.
+///               - url: A URL to associate with this extmark. In the TUI, the OSC 8 control
+///                   sequence is used to generate a clickable hyperlink to this URL.
 ///
 /// @param[out]  err   Error details, if any
 /// @return Id of the created/updated extmark
@@ -494,6 +496,7 @@ Integer nvim_buf_set_extmark(Buffer buffer, Integer ns_id, Integer line, Integer
   DecorSignHighlight sign = DECOR_SIGN_HIGHLIGHT_INIT;
   DecorVirtText virt_text = DECOR_VIRT_TEXT_INIT;
   DecorVirtText virt_lines = DECOR_VIRT_LINES_INIT;
+  char *url = NULL;
   bool has_hl = false;
 
   buf_T *buf = find_buffer_by_handle(buffer, err);
@@ -678,6 +681,10 @@ Integer nvim_buf_set_extmark(Buffer buffer, Integer ns_id, Integer line, Integer
     has_hl = true;
   }
 
+  if (HAS_KEY(opts, set_extmark, url)) {
+    url = string_to_cstr(opts->url);
+  }
+
   if (opts->ui_watched) {
     hl.flags |= kSHUIWatched;
     if (virt_text.pos == kVPosOverlay) {
@@ -747,6 +754,11 @@ Integer nvim_buf_set_extmark(Buffer buffer, Integer ns_id, Integer line, Integer
     if (kv_size(virt_lines.data.virt_lines)) {
       decor_range_add_virt(&decor_state, r, c, line2, col2, decor_put_vt(virt_lines, NULL), true);
     }
+    if (url != NULL) {
+      DecorSignHighlight sh = DECOR_SIGN_HIGHLIGHT_INIT;
+      sh.url = url;
+      decor_range_add_sh(&decor_state, r, c, line2, col2, &sh, true, 0, 0);
+    }
     if (has_hl) {
       DecorSignHighlight sh = decor_sh_from_inline(hl);
       decor_range_add_sh(&decor_state, r, c, line2, col2, &sh, true, (uint32_t)ns_id, id);
@@ -772,7 +784,14 @@ Integer nvim_buf_set_extmark(Buffer buffer, Integer ns_id, Integer line, Integer
     }
 
     uint32_t decor_indexed = DECOR_ID_INVALID;
+    if (url != NULL) {
+      DecorSignHighlight sh = DECOR_SIGN_HIGHLIGHT_INIT;
+      sh.url = url;
+      sh.next = decor_indexed;
+      decor_indexed = decor_put_sh(sh);
+    }
     if (sign.flags & kSHIsSign) {
+      sign.next = decor_indexed;
       decor_indexed = decor_put_sh(sign);
       if (sign.text[0]) {
         decor_flags |= MT_FLAG_DECOR_SIGNTEXT;
@@ -814,6 +833,10 @@ Integer nvim_buf_set_extmark(Buffer buffer, Integer ns_id, Integer line, Integer
 error:
   clear_virttext(&virt_text.data.virt_text);
   clear_virtlines(&virt_lines.data.virt_lines);
+  if (url != NULL) {
+    xfree(url);
+  }
+
   return 0;
 }
 
diff --git a/src/nvim/api/keysets_defs.h b/src/nvim/api/keysets_defs.h
index b2f0039eb9..811f60f4d6 100644
--- a/src/nvim/api/keysets_defs.h
+++ b/src/nvim/api/keysets_defs.h
@@ -54,6 +54,7 @@ typedef struct {
   Boolean spell;
   Boolean ui_watched;
   Boolean undo_restore;
+  String url;
 } Dict(set_extmark);
 
 typedef struct {
@@ -183,6 +184,7 @@ typedef struct {
   Boolean fg_indexed;
   Boolean bg_indexed;
   Boolean force;
+  String url;
 } Dict(highlight);
 
 typedef struct {
diff --git a/src/nvim/api/ui.c b/src/nvim/api/ui.c
index b42c274411..f955b315a8 100644
--- a/src/nvim/api/ui.c
+++ b/src/nvim/api/ui.c
@@ -784,6 +784,14 @@ void remote_ui_hl_attr_define(UI *ui, Integer id, HlAttrs rgb_attrs, HlAttrs cte
   MAXSIZE_TEMP_DICT(cterm, HLATTRS_DICT_SIZE);
   hlattrs2dict(&rgb, NULL, rgb_attrs, true, false);
   hlattrs2dict(&cterm, NULL, rgb_attrs, false, false);
+
+  // URLs are not added in hlattrs2dict since they are used only by UIs and not by the highlight
+  // system. So we add them here.
+  if (rgb_attrs.url >= 0) {
+    const char *url = hl_get_url((uint32_t)rgb_attrs.url);
+    PUT_C(rgb, "url", STRING_OBJ(cstr_as_string((char *)url)));
+  }
+
   ADD_C(args, DICTIONARY_OBJ(rgb));
   ADD_C(args, DICTIONARY_OBJ(cterm));
 
diff --git a/src/nvim/api/vim.c b/src/nvim/api/vim.c
index e5a5cc059f..eea9b54a5c 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -176,6 +176,12 @@ void nvim_set_hl(Integer ns_id, String name, Dict(highlight) *val, Error *err)
   });
   int link_id = -1;
 
+  // Setting URLs directly through highlight attributes is not supported
+  if (HAS_KEY(val, highlight, url)) {
+    api_free_string(val->url);
+    val->url = NULL_STRING;
+  }
+
   HlAttrs attrs = dict2hlattrs(val, true, &link_id, err);
   if (!ERROR_SET(err)) {
     ns_hl_def((NS)ns_id, hl_id, attrs, link_id, val);