fix(telegram): hard-cut when fence body cut lands on the prefix

A leading space in the fenced body made the soft cut land at min_code_pos
and re-emit the same fence forever. Require progress past the fence line.

nanobot/channels/telegram/runtime.py

@@ -102,7 +102,7 @@ def _split_telegram_markdown(content: str, max_len: int) -> list[str]:
                     adjusted = recut.rfind("\n", min_code_pos)
                     if adjusted < min_code_pos:
                         adjusted = recut.rfind(" ", min_code_pos)
-                    pos = adjusted if adjusted >= min_code_pos else budget
+                    pos = adjusted if adjusted > min_code_pos else budget
                 elif pos + len(closing) > max_len:
                     budget = max_len - len(closing)
                     if budget <= min_code_pos:
@@ -113,7 +113,11 @@ def _split_telegram_markdown(content: str, max_len: int) -> list[str]:
                     adjusted = recut.rfind("\n", min_code_pos)
                     if adjusted < min_code_pos:
                         adjusted = recut.rfind(" ", min_code_pos)
-                    pos = adjusted if adjusted >= min_code_pos else budget
+                    pos = adjusted if adjusted > min_code_pos else budget
+                if pos <= min_code_pos:
+                    chunks.append(content[:max_len])
+                    content = content[max_len:].lstrip()
+                    continue
                 chunks.append(content[:pos] + closing)
                 remainder = content[pos:]
                 if remainder.startswith("\n"):

nanobot/channels/telegram/tests/test_telegram_channel.py

@@ -293,6 +293,19 @@ def test_split_telegram_markdown_tiny_limit_with_early_body_newline() -> None:
     assert plain.count("a") >= 100
 
 
+def test_split_telegram_markdown_leading_space_in_fence_body() -> None:
+    body = "a" * 4500
+    content = f"```\n {body}"
+
+    chunks = _split_telegram_markdown(content, TELEGRAM_MAX_MESSAGE_LEN)
+
+    assert chunks
+    assert all(len(chunk) <= TELEGRAM_MAX_MESSAGE_LEN for chunk in chunks)
+    plain = "".join(chunks).replace("```", "").replace("\n", "")
+    assert plain.count("a") == 4500
+
+
+
 
 @pytest.mark.asyncio
 async def test_start_creates_separate_pools_with_proxy(monkeypatch) -> None: