rendering & chat fixes for panto cli

- resiliency for tool ids that come back from some openai_chat providers
- fixing codepoint width recognition
- implement proper rendering for full markdown as seen from ai models

1 files changed, 14 insertions, 0 deletions

diff --git a/src/tui_engine.zig b/src/tui_engine.zig
index 4924347..a779747 100644
--- a/src/tui_engine.zig
+++ b/src/tui_engine.zig
@@ -80,6 +80,17 @@ pub fn visibleWidth(line: []const u8) usize {
             i += skipEscape(line[i..]);
             continue;
         }
+        if (b == '\t') {
+            const rem = cols % 8;
+            cols += if (rem == 0) 8 else 8 - rem;
+            i += 1;
+            continue;
+        }
+        if (b == '\r') {
+            cols = 0;
+            i += 1;
+            continue;
+        }
         // Count one column per UTF-8 codepoint start byte.
         const seq_len = std.unicode.utf8ByteSequenceLength(b) catch 1;
         cols += 1;
@@ -1010,6 +1021,9 @@ test "visibleWidth strips CSI and counts codepoints" {
     try testing.expectEqual(@as(usize, 5), visibleWidth("hello"));
     try testing.expectEqual(@as(usize, 5), visibleWidth("\x1b[2mhello\x1b[0m"));
     try testing.expectEqual(@as(usize, 0), visibleWidth("\x1b[0m"));
+    try testing.expectEqual(@as(usize, 8), visibleWidth("\t"));
+    try testing.expectEqual(@as(usize, 9), visibleWidth("a\tX"));
+    try testing.expectEqual(@as(usize, 9), visibleWidth("prepainted\r\tX"));
     // CURSOR_MARKER (APC string) is zero-width.
     try testing.expectEqual(@as(usize, 2), visibleWidth("a" ++ CURSOR_MARKER ++ "b"));
     // multibyte UTF-8 counts one column per codepoint.