tui: one shared field editor, in-place form editing, value-only focus

Forms edit fields in place in the value column instead of a bottom
prompt, highlight only the focused value and scroll when taller than the
screen; long text scrolls horizontally instead of wrapping. Fixes: typing
after Backspace/Del no longer wipes the field, 'q' is text in row tables,
the caret resets between cells, dialogs decode arrow keys, full buffers
never take half a UTF-8 character, an invalid amount stays editable.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 11 insertions, 1 deletions

diff --git a/clients/tui.h b/clients/tui.h
index 1785a32..5ede574 100644
--- a/clients/tui.h
+++ b/clients/tui.h
@@ -99,7 +99,14 @@ int tui_field_edit(char *buf, size_t cap, size_t *pos, int ch, int *fresh);
 int tui_date_field_edit(char *buf, size_t cap, size_t *pos, int ch,
                         int *fresh);
 
-/* Line editor at (y,x) with the label already drawn. Returns 1 on Enter,
+/* First byte to show so the caret at byte pos is visible in a field of
+   width columns (one column is kept for the caret after the last
+   character). `start` is the previous value: it is kept while the caret
+   stays visible, and moved back when removed text makes room. Pure. */
+size_t tui_field_scroll(const char *buf, size_t pos, int width, size_t start);
+
+/* Line editor at (y,x) up to the right border, scrolling horizontally,
+   with the label already drawn. Edits buf in place. Returns 1 on Enter,
    2 on Tab, 3 on Shift-Tab, 0 on Esc. */
 int tui_edit_field(int y, int x, char *buf, size_t cap, int mask);
 
@@ -187,6 +194,8 @@ struct tui_form_field {
 };
 
 int tui_form_next(int sel, int n, int ch);
+/* First visible form line so line sl of nlines shows in view lines. Pure. */
+int tui_form_scroll(int top, int sl, int nlines, int view);
 
 int tui_form_run(const char *title, struct tui_form_field *f, int n,
                  int can_edit, int *focus);
@@ -283,6 +292,7 @@ struct tui_rt {
     int row, col;
     int fresh;
     size_t pos;
+    size_t hscroll; /* first byte shown in the focused cell */
     void (*cell)(void *, int, int, char **, size_t *);
     void (*info)(void *, int, char *, size_t);
     void *ud;