fix(kb-mode): sanitize AskUserQuestion box-drawing + render prompt as code block

src/ccbot/handlers/card_model.py

@@ -817,6 +817,37 @@ def render_page(events: list[Event], now: float) -> str:
 # ─── Card composition ─────────────────────────────────────────────────
 
 
+# Box-drawing / block-element glyphs (U+2500–U+259F). Claude Code's
+# AskUserQuestion renders each option's ``preview`` inside a box-drawing
+# frame (``┌ │ ├ ─ …``); captured verbatim into the kb-mode card those
+# borders mangle the body. We strip them on the kb-mode path.
+_BOX_DRAWING_RE = re.compile(r"[─-▟]")
+_BORDER_ONLY_LINE_RE = re.compile(r"^[\s─-▟]*$")
+
+
+def _sanitize_prompt_block(text: str) -> str:
+    """Strip terminal box-drawing borders from a captured interactive prompt.
+
+    Drops border-only lines and removes box-drawing glyphs from content
+    lines (preserving indentation + internal spacing). Collapses 3+ blank
+    lines that the border removal can leave behind.
+    """
+    out: list[str] = []
+    for line in text.splitlines():
+        if _BORDER_ONLY_LINE_RE.match(line):
+            # Keep a single blank as a paragraph break, drop runs.
+            if out and out[-1] != "":
+                out.append("")
+            continue
+        cleaned = _BOX_DRAWING_RE.sub("", line).rstrip()
+        out.append(cleaned)
+    while out and out[0] == "":
+        out.pop(0)
+    while out and out[-1] == "":
+        out.pop()
+    return "\n".join(out)
+
+
 def _render_card(
     sess: Session,
     state: CardState,
@@ -841,7 +872,13 @@ def _render_card(
     # keyboard. The regular event log is BELOW the keyboard (footer'd by
     # the keyboard rather than by switcher/pagination). See Task #41.
     if state.in_kb_mode and state.kb_prompt:
-        parts = [header, "─────", "⌨ *Waiting for your input:*", state.kb_prompt]
+        body = _sanitize_prompt_block(state.kb_prompt)
+        # Render the prompt as a fenced code block so telegramify treats it
+        # as literal monospace: no MarkdownV2 escaping noise, and no
+        # auto-collapse into an expandable blockquote (the "✂ N lines
+        # hidden" artifact). Guard the rare case of a ``` inside the prompt.
+        prompt_part = body if "```" in body else f"```\n{body}\n```"
+        parts = [header, "─────", "⌨ *Waiting for your input:*", prompt_part]
         return "\n".join(parts)
 
     # Budget is in LINES (per user setting ``card_page_lines``).

tests/test_kb_prompt_sanitize.py

@@ -0,0 +1,93 @@
+"""Regression test: kb-mode prompt sanitization.
+
+Claude Code's AskUserQuestion renders each option's ``preview`` inside
+box-drawing frames (``┌ │ ├ ─ …``). Captured verbatim into the kb-mode
+card those borders mangled the body, and telegramify auto-collapsed the
+long region into an expandable blockquote ("✂ N lines hidden"). The
+kb-mode render now strips box-drawing borders and wraps the prompt in a
+fenced code block so it renders as literal monospace.
+"""
+
+from __future__ import annotations
+
+from ccbot.handlers.card_model import (
+    CardState,
+    _render_card,
+    _sanitize_prompt_block,
+)
+from ccbot.session_models import Session
+
+# Reconstruction of the reported pane: option previews inside box frames.
+BOXED_PROMPT = (
+    "□ Механизм\n"
+    "Каким механизмом сделать автозапуск ccbot при загрузке телефона?\n"
+    "\n"
+    "1. Magisk service.d\n"
+    "  ┌─────────────────────────────────┐\n"
+    "  │ /data/adb/service.d/99-ccbot.sh  │\n"
+    "  ├─────────────────────────────────┤\n"
+    "2. Termux:Boot\n"
+    "3. Оба слоя\n"
+    "Enter to select · ↑/↓ to navigate · Esc to cancel\n"
+)
+
+
+def _has_box_drawing(text: str) -> bool:
+    return any(0x2500 <= ord(c) <= 0x259F for c in text)
+
+
+def _sess() -> Session:
+    return Session(id="s1", name="t", window_id="@1", workdir="/tmp", state="active")
+
+
+class TestSanitizePromptBlock:
+    def test_strips_all_box_drawing(self):
+        out = _sanitize_prompt_block(BOXED_PROMPT)
+        assert not _has_box_drawing(out)
+
+    def test_preserves_content(self):
+        out = _sanitize_prompt_block(BOXED_PROMPT)
+        assert "/data/adb/service.d/99-ccbot.sh" in out
+        assert "Magisk service.d" in out
+        assert "Termux:Boot" in out
+        assert "Оба слоя" in out
+
+    def test_keeps_checkbox_header_glyph(self):
+        # □ (U+25A1) is outside the stripped U+2500–U+259F range → kept.
+        out = _sanitize_prompt_block(BOXED_PROMPT)
+        assert "□ Механизм" in out
+
+    def test_border_only_lines_dropped(self):
+        # The ┌──┐ / ├──┤ frame lines must not survive as content.
+        out = _sanitize_prompt_block(BOXED_PROMPT)
+        for line in out.splitlines():
+            assert "┌" not in line and "┐" not in line and "├" not in line
+
+    def test_empty_input(self):
+        assert _sanitize_prompt_block("") == ""
+
+
+class TestKbModeRender:
+    def test_prompt_wrapped_in_code_fence(self):
+        st = CardState()
+        st.in_kb_mode = True
+        st.kb_prompt = BOXED_PROMPT
+        out = _render_card(_sess(), st, user_id=1)
+        assert "⌨" in out  # waiting-for-input header present
+        assert "```" in out  # prompt rendered as a fenced code block
+
+    def test_no_frame_chars_in_rendered_body(self):
+        st = CardState()
+        st.in_kb_mode = True
+        st.kb_prompt = BOXED_PROMPT
+        out = _render_card(_sess(), st, user_id=1)
+        # Frame glyphs (only from kb_prompt) are gone. The card's own
+        # "─────" separator (U+2500) is allowed and not asserted against.
+        assert "┌" not in out and "│" not in out and "├" not in out
+
+    def test_content_survives_render(self):
+        st = CardState()
+        st.in_kb_mode = True
+        st.kb_prompt = BOXED_PROMPT
+        out = _render_card(_sess(), st, user_id=1)
+        assert "/data/adb/service.d/99-ccbot.sh" in out