1 files changed, 29 insertions, 6 deletions
diff --git a/src/pardes.zig b/src/pardes.zig
index 65f3aebb..321a6b3c 100644
--- a/src/pardes.zig
+++ b/src/pardes.zig
@@ -4976,16 +4976,14 @@ pub const Pardes = struct {
             if (t.what != .body) {
                 // An explicit selection, else the word under the cursor in the
                 // text as it is shown: a tag's prefix is part of what a word is.
-                const arena = p.scratch.allocator();
-                const own = arena.dupe(u8, edit.flatSurface(p, t) catch return) catch return;
-                const shown = if (t.what == .tag) tagline.tagText(p, arena, pane) catch return else own;
-                const range = t.primaryRange(own, 0);
+                const shown = p.scratch.allocator().dupe(u8, edit.flatSurface(p, t) catch return) catch return;
+                const range = t.primaryRange(shown, 0);
                 const lo = @min(range.anchor, range.head);
                 const hi = @max(range.anchor, range.head);
                 const txt = if ((t.vsel.active and t.vsel.explicit) or t.msel.active)
-                    own[lo..hi]
+                    shown[lo..hi]
                 else word: {
-                    const b = config.wordBounds(shown, shown.len - own.len + modal.selectionCursor(own, range));
+                    const b = config.wordBounds(shown, modal.selectionCursor(shown, range));
                     break :word shown[b.lo..b.hi];
                 };
                 // Out of the tag or header FIRST: Del frees the pane, Kill
@@ -5013,6 +5011,14 @@ pub const Pardes = struct {
             return;
         }
         if (t.mode == .normal and t.what == .body and pane.hasPdf()) return normal.handlePdfNormal(p, pane, key);
+        if (t.what == .tag and t.mode == .insert and tagline.typedIntoName(p, pane, key)) return;
+        // A tag's prefix is read-only: a key whose edit reached into it
+        // changes nothing, not even where the cursor is.
+        const kept = .{ t.cur_row, t.cur_col, t.vsel, t.msel, t.sels, t.nsel };
+        t.refused = false;
+        defer if (t.refused) {
+            t.cur_row, t.cur_col, t.vsel, t.msel, t.sels, t.nsel = kept;
+        };
         switch (t.mode) {
             .normal => normal.handleNormal(p, t, key),
             .insert => {
@@ -5597,6 +5603,23 @@ pub const Pardes = struct {
             const r = p.rects[id];
             // The tag takes a row per line, leaving the body one row if it
             // had any; a folded pane shows its first line only.
+            // Measured on the stack: this runs on every event, and not
+            // every event may take from the scratch arena.
+            var room: [2 * limits.host_path_cap + 256]u8 = undefined;
+            var measure = std.heap.FixedBufferAllocator.init(&room);
+            const lead = if (tagline.prefixIn(measure.allocator(), pane)) |prefix| prefix.len else |_| pane.tag_lead;
+            if (lead != pane.tag_lead) {
+                const t = &pane.tag;
+                const old: i32 = @intCast(pane.tag_lead);
+                const new: i32 = @intCast(lead);
+                if (t.cur_row == 0 and t.cur_col >= old) t.cur_col += new - old;
+                if (t.vsel.row == 0 and t.vsel.col >= old) t.vsel.col += new - old;
+                for (t.sels[0..t.nsel]) |*sel| {
+                    if (sel.row == 0 and sel.col >= old) sel.col += new - old;
+                    if (sel.arow == 0 and sel.acol >= old) sel.acol += new - old;
+                }
+                pane.tag_lead = lead;
+            }
             const lines = std.mem.count(u8, tagline.curTail(pane), "\n") + 1;
             pane.tag_rows = @intCast(@min(lines, MAX_TAG_ROWS, @max(BOX_H, r.h -| 1)));
             if (pane.collapsed) pane.tag_rows = BOX_H;