TUI: mouse drag selection with OSC 52 copy; Markdown emphasis follows CommonMark; v0.5.0

- Drag, double-click (word) and triple-click (line) selection in the log,
  auto-scroll at the edges, soft-wrapped lines joined on copy.
- sashidown ANSI renderer: delimiter runs with flanking rules, so
  intraword underscores (test_apply_patch.c) stay literal; unmatched
  * _ and backticks are shown as-is; * and _ do not close each other.
- tests: test_textsel, test_markdown.

src/tui.c

@@ -10,6 +10,7 @@
 #include "cst_plugins.h"
 #include "cst_skills.h"
 #include "cst_subagent.h"
+#include "cst_textsel.h"
 #include "cst_perms.h"
 #include "cst_sandbox.h"
 #include "cst_tools.h"
@@ -61,23 +62,7 @@ static int g_utf8 = 1; /* locale can show non-ASCII text */
 #ifndef KEY_RESIZE
 #define KEY_RESIZE 0632
 #endif
-/* MinGW often lacks wcwidth; simple East-Asian / ASCII heuristic. */
-static int cst_wcwidth(wchar_t wc) {
-  if (wc == 0)
-    return 0;
-  if (wc < 32 || (wc >= 0x7f && wc < 0xa0))
-    return -1;
-  if (wc >= 0x1100 &&
-      (wc <= 0x115f || wc == 0x2329 || wc == 0x232a ||
-       (wc >= 0x2e80 && wc <= 0xa4cf && wc != 0x303f) ||
-       (wc >= 0xac00 && wc <= 0xd7a3) || (wc >= 0xf900 && wc <= 0xfaff) ||
-       (wc >= 0xfe10 && wc <= 0xfe19) || (wc >= 0xfe30 && wc <= 0xfe6f) ||
-       (wc >= 0xff00 && wc <= 0xff60) || (wc >= 0xffe0 && wc <= 0xffe6) ||
-       (wc >= 0x20000 && wc <= 0x2fffd) || (wc >= 0x30000 && wc <= 0x3fffd)))
-    return 2;
-  return 1;
-}
-#define wcwidth cst_wcwidth
+#define wcwidth cst_wcwidth /* MinGW often lacks wcwidth */
 #else
 #include <ncurses.h>
 #endif
@@ -139,6 +124,12 @@ static int cst_clock_gettime_mono(struct timespec *ts) {
 #define KEY_KITTY_REPLY (KEY_OWN_BASE + 3)
 #define KEY_KITTY_BASE (KEY_OWN_BASE + 16)
 #define KITTY_CP_END 128
+/* Transcript selection states. */
+#define SEL_NONE 0
+#define SEL_PRESS 1 /* button down, not moved off the pressed cell yet */
+#define SEL_DRAG 2
+#define SEL_SHOWN 3 /* released; highlighted until the next input */
+#define MULTI_CLICK_MS 400
 
 #ifdef NCURSES_VERSION
 static int g_kitty_on;
@@ -301,6 +292,15 @@ typedef struct {
   int row_blk_cap;
   int cmd_x0, cmd_x1;         /* "ctrl+p commands" in the status row */
   int mouse_on;
+  int log_start;              /* display line shown in logw row 0 */
+  /* Mouse selection in the transcript: display line + logw column. */
+  int sel_state;              /* SEL_* */
+  int sel_mode;               /* 1 characters, 2 words, 3 lines */
+  int sel_ay, sel_ax;         /* anchor */
+  int sel_y, sel_x;           /* current end */
+  int sel_press_y, sel_press_x; /* screen cell of the press */
+  int sel_clicks, sel_click_y, sel_click_x;
+  struct timespec sel_click_at;
   const char *tip;
   const char *sandbox_name;   /* "landlock" / "seatbelt" / "rules" */
   char where[300];            /* ~/path:branch */
@@ -404,26 +404,10 @@ static size_t utf8_prev_len(const char *s, size_t len) {
 }
 
 static int utf8_decode(const char *s, size_t avail, wchar_t *wc, size_t *eaten) {
-  if (avail == 0)
-    return -1;
-  mbstate_t st;
-  memset(&st, 0, sizeof(st));
-  size_t n = mbrtowc(wc, s, avail, &st);
-  if (n == (size_t)-1 || n == (size_t)-2 || n == 0) {
-    *wc = (unsigned char)s[0];
-    *eaten = 1;
-    return 0;
-  }
-  *eaten = n;
-  return 0;
+  return cst_utf8_decode(s, avail, wc, eaten);
 }
 
-static int utf8_width(wchar_t wc) {
-  int w = wcwidth(wc);
-  if (w < 0)
-    return 1;
-  return w;
-}
+static int utf8_width(wchar_t wc) { return cst_utf8_width(wc); }
 
 static int utf8_cols(const char *s, size_t n) {
   int cols = 0;
@@ -454,20 +438,7 @@ static size_t utf8_fit_cols(const char *s, size_t n, int max_cols) {
   return i;
 }
 
-static size_t ansi_skip(const char *s, size_t n) {
-  if (n < 2 || (unsigned char)s[0] != 0x1b)
-    return 0;
-  if (s[1] == '[') {
-    size_t i = 2;
-    while (i < n) {
-      unsigned char c = (unsigned char)s[i++];
-      if (c >= 0x40 && c <= 0x7e)
-        return i;
-    }
-    return 0;
-  }
-  return 2;
-}
+static size_t ansi_skip(const char *s, size_t n) { return cst_ansi_skip(s, n); }
 
 static char *xstrdup(const char *s) {
   if (!s)
@@ -1272,6 +1243,8 @@ typedef struct {
   int fill;   /* pair painted across the whole row (0 = none) */
   int bar;    /* pair for a "┃" in column 0 (0 = none) */
   int blk;    /* hist block index, -1 for live / none */
+  int cont;     /* soft-wrapped continuation of the previous row */
+  int cont_pad; /* leading columns of a continuation that only indent */
 } dline_t;
 
 static int g_dl_blk = -1; /* block being flattened, stamped into dline_t */
@@ -1311,6 +1284,8 @@ static int dlines_push(dlines_t *dl, const char *text, int pair, int bold,
   L->fill = 0;
   L->bar = 0;
   L->blk = g_dl_blk;
+  L->cont = 0;
+  L->cont_pad = 0;
   return 0;
 }
 
@@ -1341,10 +1316,10 @@ static void push_wrapped(dlines_t *dl, const char *prefix, const char *body,
   /* Walk body; for ANSI text, wrap on visible columns skipping SGR. */
   size_t n = strlen(body);
   size_t i = 0;
-  int first = 1;
+  int first = 1, soft = 0;
   while (i < n && dl->n < MAX_RENDER_LINES) {
     size_t start = i;
-    int col = 0;
+    int col = 0, pad = 0;
     while (i < n) {
       size_t sg = 0;
       if ((unsigned char)body[i] == 0x1b) {
@@ -1387,7 +1362,7 @@ static void push_wrapped(dlines_t *dl, const char *prefix, const char *body,
       first = 0;
     } else {
       /* continuation indent matching prefix visual width */
-      int pad = pref_cols;
+      pad = pref_cols;
       if (pad < 0)
         pad = 0;
       if (pad > 40)
@@ -1400,10 +1375,11 @@ static void push_wrapped(dlines_t *dl, const char *prefix, const char *body,
         line[pad] = 0;
       }
     }
-    dlines_push(dl, line, pair, bold, dim);
-    if (i < n && body[i - 1] != '\n' && col >= body_w) {
-      /* soft wrap — already advanced */
+    if (dlines_push(dl, line, pair, bold, dim) == 0 && soft) {
+      dl->lines[dl->n - 1].cont = 1;
+      dl->lines[dl->n - 1].cont_pad = pad;
     }
+    soft = body[i - 1] != '\n';
   }
 }
 
@@ -2338,7 +2314,7 @@ static const char *const TIPS[] = {
     "/undo reverts the file changes of the last turn",
     "/provider switches provider; keys are saved per provider",
     "Click a tool card or Thought to expand it",
-    "Shift+drag selects text while mouse support is on",
+    "Drag over the transcript to copy it; double-click copies a word",
 };
 
 static void draw_home(tui_t *t) {
@@ -2548,6 +2524,57 @@ static void draw_side(tui_t *t) {
   wrefresh(s);
 }
 
+/* Ordered selection [y1:x1, y2:x2] over display lines, snapped to words or
+ * whole lines by the click count; x2 < 0 means the end of the line. */
+static void sel_range(const tui_t *t, const dlines_t *dl, int *y1, int *x1,
+                      int *y2, int *x2) {
+  int ay = t->sel_ay, ax = t->sel_ax, by = t->sel_y, bx = t->sel_x;
+  if (by < ay || (by == ay && bx < ax)) {
+    int ty = ay, tx = ax;
+    ay = by, ax = bx, by = ty, bx = tx;
+  }
+  if (t->sel_mode == 2) {
+    int c1, c2;
+    if (ay >= 0 && ay < dl->n) {
+      cst_textsel_word(dl->lines[ay].text, dl->lines[ay].indent, ax, &c1, &c2);
+      ax = c1;
+    }
+    if (by >= 0 && by < dl->n) {
+      cst_textsel_word(dl->lines[by].text, dl->lines[by].indent, bx, &c1, &c2);
+      bx = c2;
+    }
+  } else if (t->sel_mode == 3) {
+    while (ay > 0 && ay < dl->n && dl->lines[ay].cont)
+      ay--;
+    while (by + 1 < dl->n && dl->lines[by + 1].cont)
+      by++;
+    ax = 0;
+    bx = -1;
+  }
+  *y1 = ay, *x1 = ax, *y2 = by, *x2 = bx;
+}
+
+static void draw_selection(tui_t *t, const dlines_t *dl, int h, int w) {
+  if (t->sel_state != SEL_DRAG && t->sel_state != SEL_SHOWN)
+    return;
+  int y1, x1, y2, x2;
+  sel_range(t, dl, &y1, &x1, &y2, &x2);
+  for (int row = 0; row < h; row++) {
+    int li = t->log_start + row;
+    if (li < y1 || li > y2)
+      continue;
+    int a = li == y1 ? x1 : 0;
+    int b = li == y2 && x2 >= 0 ? x2 : w - 1;
+    if (li < dl->n)
+      cst_textsel_snap(dl->lines[li].text, dl->lines[li].indent, &a, &b);
+    if (b >= w)
+      b = w - 1;
+    if (a <= b)
+      mvwchgat(t->logw, row, a, b - a + 1, A_REVERSE,
+               HAS_COLOR() ? CP_PANEL : 0, NULL);
+  }
+}
+
 static void draw_log(tui_t *t) {
   if (!t->logw)
     return;
@@ -2581,6 +2608,7 @@ static void draw_log(tui_t *t) {
   int start = total - h - t->log_scroll;
   if (start < 0)
     start = 0;
+  t->log_start = start;
 
   if (t->row_blk_cap < h) {
     int *nb = realloc(t->row_blk, (size_t)h * sizeof(int));
@@ -2604,6 +2632,7 @@ static void draw_log(tui_t *t) {
     if (L->bar)
       put_wc(t->logw, row, 0, L'┃', HAS_COLOR() ? (int)COLOR_PAIR(L->bar) : 0);
   }
+  draw_selection(t, &dl, h, w);
   if (t->log_scroll > 0 && h > 2) {
     char more[128];
     snprintf(more, sizeof(more),
@@ -2777,8 +2806,17 @@ static int input_visual_rows(const tui_t *t) {
 }
 
 static void apply_mouse(const tui_t *t) {
-  mousemask(t->mouse_on ? (mmask_t)ALL_MOUSE_EVENTS : 0, NULL);
+  mousemask(t->mouse_on ? (mmask_t)(ALL_MOUSE_EVENTS | REPORT_MOUSE_POSITION)
+                        : 0,
+            NULL);
   mouseinterval(0);
+#ifdef NCURSES_VERSION
+  /* ncurses only asks for presses and releases (1000). 1002 also reports
+   * motion while a button is held, for drag selection; terminals treat it as
+   * replacing 1000, so it goes after mousemask and is turned off explicitly. */
+  printf(t->mouse_on ? "\033[?1002h" : "\033[?1002l");
+  fflush(stdout);
+#endif
 }
 
 static void free_windows(tui_t *t) {
@@ -3919,7 +3957,7 @@ static void cmd_help(tui_t *t, char *arg, int *quit) {
   push_system_line(t, "  Enter send · Esc cancel turn · Ctrl+C twice or Ctrl+D "
                       "quit · Ctrl+P command palette");
   push_system_line(t, "  Mouse: click cards / Thought to expand, wheel scrolls, "
-                      "Shift+drag selects · /mouse");
+                      "drag copies (double-click word, triple line) · /mouse");
   push_system_line(t, "  Rebind in keybinds.json next to settings.json");
   push_system_line(t, "");
 }
@@ -4346,8 +4384,10 @@ static void cmd_mouse(tui_t *t, char *arg, int *quit) {
   (void)quit;
   t->mouse_on = !t->mouse_on;
   apply_mouse(t);
-  push_system_line(t, t->mouse_on ? "(mouse on · Shift+drag selects text)"
-                                  : "(mouse off · the terminal selects text)");
+  push_system_line(t, t->mouse_on
+                          ? "(mouse on · drag selects and copies (OSC 52) · "
+                            "Shift+drag uses the terminal's own selection)"
+                          : "(mouse off · the terminal selects text)");
 }
 
 static void cmd_max_steps(tui_t *t, char *arg, int *quit) {
@@ -4533,25 +4573,16 @@ static void cmd_export(tui_t *t, char *arg, int *quit) {
   push_system_line(t, "(exported to %s)", path);
 }
 
-static void cmd_copy(tui_t *t, char *arg, int *quit) {
-  (void)arg;
-  (void)quit;
-  const char *text = NULL;
-  for (int i = t->hist.n - 1; i >= 0 && !text; i--)
-    if (t->hist.items[i].kind == BLK_ASSISTANT && t->hist.items[i].body)
-      text = t->hist.items[i].body;
-  if (!text || !text[0]) {
-    push_system_line(t, "Nothing to copy yet");
-    return;
-  }
+/* Puts text on the terminal's clipboard; returns the bytes sent, 0 on
+ * failure. */
+static size_t osc52_copy(const char *text, size_t n) {
   static const char b64[] =
       "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
-  size_t n = strlen(text);
   if (n > 75000)
     n = 75000; /* many terminals cap OSC 52 near 100 KB */
   char *enc = malloc((n + 2) / 3 * 4 + 1);
   if (!enc)
-    return;
+    return 0;
   size_t o = 0;
   for (size_t i = 0; i < n; i += 3) {
     unsigned v = (unsigned char)text[i] << 16;
@@ -4571,8 +4602,24 @@ static void cmd_copy(tui_t *t, char *arg, int *quit) {
     printf("\033]52;c;%s\a", enc);
   fflush(stdout);
   free(enc);
-  push_system_line(t, "(copied %zu bytes of the last reply via OSC 52 — the "
-                      "terminal must allow clipboard access)", n);
+  return n;
+}
+
+static void cmd_copy(tui_t *t, char *arg, int *quit) {
+  (void)arg;
+  (void)quit;
+  const char *text = NULL;
+  for (int i = t->hist.n - 1; i >= 0 && !text; i--)
+    if (t->hist.items[i].kind == BLK_ASSISTANT && t->hist.items[i].body)
+      text = t->hist.items[i].body;
+  if (!text || !text[0]) {
+    push_system_line(t, "Nothing to copy yet");
+    return;
+  }
+  size_t n = osc52_copy(text, strlen(text));
+  if (n)
+    push_system_line(t, "(copied %zu bytes of the last reply via OSC 52 — the "
+                        "terminal must allow clipboard access)", n);
 }
 
 static void cmd_init(tui_t *t, char *arg, int *quit) {
@@ -4906,7 +4953,7 @@ static const slash_cmd_t SLASH[] = {
      1, cmd_approval},
     {"yolo", "", "", "toggle approving everything", 1, cmd_yolo},
     {"sidebar", "", "", "show or hide the session sidebar", 1, cmd_sidebar},
-    {"mouse", "", "", "toggle mouse support (Shift+drag selects)", 1,
+    {"mouse", "", "", "toggle mouse support (drag copies)", 1,
      cmd_mouse},
     {"max-steps", "", "[N]", "tool steps allowed per turn", 1, cmd_max_steps},
     {"status", "", "", "session, model, context and settings", 1, cmd_status},
@@ -5437,6 +5484,145 @@ static int handle_click(tui_t *t, int y, int x, int busy) {
   return 0;
 }
 
+/* Transcript cell under screen (y, x) as display line + column. Outside the
+ * transcript returns 0, unless `clamp` pulls the point to its nearest edge. */
+static int log_cell(const tui_t *t, int y, int x, int clamp, int *li,
+                    int *col) {
+  if (t->home || !t->logw)
+    return 0;
+  int lh, lw;
+  getmaxyx(t->logw, lh, lw);
+  int ry = y - t->log_y, rx = x - t->log_x;
+  if (!clamp && (ry < 0 || ry >= lh || rx < 0 || rx >= lw))
+    return 0;
+  *li = t->log_start + clampi(ry, 0, lh - 1);
+  *col = clampi(rx, 0, lw - 1);
+  return 1;
+}
+
+static void sel_clear(tui_t *t) {
+  int shown = t->sel_state == SEL_DRAG || t->sel_state == SEL_SHOWN;
+  t->sel_state = SEL_NONE;
+  if (shown)
+    draw_log(t);
+}
+
+static void sel_copy(tui_t *t) {
+  int h, w;
+  getmaxyx(t->logw, h, w);
+  (void)h;
+  dlines_t dl = {0};
+  build_display(t, &dl, w);
+  int y1, x1, y2, x2;
+  sel_range(t, &dl, &y1, &x1, &y2, &x2);
+  cst_selbuf_t b = {0};
+  for (int k = y1 < 0 ? 0 : y1; k <= y2 && k < dl.n; k++) {
+    const dline_t *L = &dl.lines[k];
+    int c1 = k == y1 ? x1 : 0, c2 = k == y2 ? x2 : -1;
+    if (k > y1) {
+      if (!L->cont)
+        cst_selbuf_putc(&b, '\n');
+      else if (c1 < L->indent + L->cont_pad)
+        c1 = L->indent + L->cont_pad;
+    }
+    int joined = k < y2 && k + 1 < dl.n && dl.lines[k + 1].cont;
+    cst_textsel_append(&b, L->text, L->indent, c1, c2, !joined);
+  }
+  dlines_free(&dl);
+  if (b.n && osc52_copy(b.s, b.n)) {
+    size_t chars = 0;
+    for (size_t i = 0; i < b.n; i++)
+      chars += ((unsigned char)b.s[i] & 0xC0) != 0x80;
+    char msg[96];
+    snprintf(msg, sizeof(msg), "Copied %zu characters (OSC 52)", chars);
+    set_status(t, msg);
+    draw_status(t);
+  }
+  cst_selbuf_free(&b);
+}
+
+/* Drag while the button is held: extend the selection, scrolling the
+ * transcript when the pointer is above or below it. */
+static void sel_motion(tui_t *t, int y, int x) {
+  int lh, lw;
+  getmaxyx(t->logw, lh, lw);
+  (void)lw;
+  int ry = y - t->log_y;
+  if (ry < 0 || ry >= lh) {
+    int before = t->log_scroll;
+    t->log_scroll += ry < 0 ? 1 : -1;
+    if (t->log_scroll < 0)
+      t->log_scroll = 0;
+    if (t->log_scroll != before)
+      draw_log(t); /* updates log_start */
+  }
+  int li, col;
+  if (!log_cell(t, y, x, 1, &li, &col))
+    return;
+  if (t->sel_state == SEL_PRESS && li == t->sel_ay && col == t->sel_ax)
+    return;
+  t->sel_state = SEL_DRAG;
+  t->sel_y = li;
+  t->sel_x = col;
+  draw_log(t);
+}
+
+/* Wheel, clicks and drag selection; -2 means quit. */
+static int on_mouse(tui_t *t, const MEVENT *ev, int busy) {
+  mmask_t b = ev->bstate;
+  if (b & BUTTON4_PRESSED) {
+    t->log_scroll += SCROLL_SPEED;
+    draw_log(t);
+    return 0;
+  }
+  if (b & BUTTON5_PRESSED) {
+    t->log_scroll -= SCROLL_SPEED;
+    if (t->log_scroll < 0)
+      t->log_scroll = 0;
+    draw_log(t);
+    return 0;
+  }
+  if (b & REPORT_MOUSE_POSITION) {
+    if (t->sel_state == SEL_PRESS || t->sel_state == SEL_DRAG)
+      sel_motion(t, ev->y, ev->x);
+    return 0;
+  }
+  if (b & (BUTTON1_PRESSED | BUTTON1_CLICKED)) {
+    sel_clear(t);
+    int li, col;
+    if (!(b & BUTTON1_PRESSED) || !log_cell(t, ev->y, ev->x, 0, &li, &col))
+      return handle_click(t, ev->y, ev->x, busy);
+    if (t->sel_clicks && since_ms(&t->sel_click_at) < MULTI_CLICK_MS &&
+        li == t->sel_click_y && abs(col - t->sel_click_x) <= 1)
+      t->sel_clicks = t->sel_clicks % 3 + 1;
+    else
+      t->sel_clicks = 1;
+    clock_gettime(CLOCK_MONOTONIC, &t->sel_click_at);
+    t->sel_click_y = li;
+    t->sel_click_x = col;
+    t->sel_mode = t->sel_clicks;
+    t->sel_ay = t->sel_y = li;
+    t->sel_ax = t->sel_x = col;
+    t->sel_press_y = ev->y;
+    t->sel_press_x = ev->x;
+    t->sel_state = t->sel_clicks > 1 ? SEL_DRAG : SEL_PRESS;
+    if (t->sel_state == SEL_DRAG)
+      draw_log(t);
+    return 0;
+  }
+  if (b & BUTTON1_RELEASED) {
+    if (t->sel_state == SEL_PRESS) {
+      t->sel_state = SEL_NONE;
+      return handle_click(t, t->sel_press_y, t->sel_press_x, busy);
+    }
+    if (t->sel_state == SEL_DRAG) {
+      sel_copy(t);
+      t->sel_state = SEL_SHOWN;
+    }
+  }
+  return 0;
+}
+
 /* Tab completes after "/" at the start or an "@word" under the cursor. */
 static int wants_completion(const tui_t *t) {
   if (t->in_len && t->inbuf[0] == '/')
@@ -6192,6 +6378,9 @@ int cst_tui_run(cst_agent_t *agent) {
     int rc = tui_wget_wch(t.input, &wch);
     if (rc == ERR)
       continue;
+    if (t.sel_state == SEL_SHOWN &&
+        !(rc == KEY_CODE_YES && (wch == KEY_MOUSE || wch == KEY_RESIZE)))
+      sel_clear(&t);
 
     if (!t.in_paste &&
         !(rc == KEY_CODE_YES &&
@@ -6263,6 +6452,7 @@ int cst_tui_run(cst_agent_t *agent) {
         continue;
       }
       if (wch == KEY_RESIZE) {
+        t.sel_state = SEL_NONE; /* display lines rewrap */
         layout(&t);
         wtimeout(t.input, 80);
         redraw_all(&t);
@@ -6271,18 +6461,8 @@ int cst_tui_run(cst_agent_t *agent) {
       if (wch == KEY_MOUSE) {
         MEVENT ev;
         if (getmouse(&ev) == OK) {
-          if (ev.bstate & BUTTON4_PRESSED) {
-            t.log_scroll += SCROLL_SPEED;
-            draw_log(&t);
-          } else if (ev.bstate & BUTTON5_PRESSED) {
-            t.log_scroll -= SCROLL_SPEED;
-            if (t.log_scroll < 0)
-              t.log_scroll = 0;
-            draw_log(&t);
-          } else if (ev.bstate & (BUTTON1_PRESSED | BUTTON1_CLICKED)) {
-            if (handle_click(&t, ev.y, ev.x, busy) == -2)
-              goto out;
-          }
+          if (on_mouse(&t, &ev, busy) == -2)
+            goto out;
           draw_input(&t); /* keep the terminal cursor in the box */
         }
         continue;
@@ -6495,7 +6675,7 @@ out:
   tui_free(&t);
 #ifdef NCURSES_VERSION
   kitty_restore();
-  printf("\033[?2004l");
+  printf("\033[?1002l\033[?2004l");
   fflush(stdout);
 #endif
   endwin();