core/cli: Rich markdown for assistant text at end of turn

Stream plain tokens; on TTY re-render with Rich. /markdown and PLYNGENT_PLAIN.

tests/test_cli/test_display.py

@@ -3,7 +3,14 @@ from __future__ import annotations
 from typing import TYPE_CHECKING
 
 from plyngent.agent import ReasoningDeltaEvent, TextDeltaEvent, ToolResultEvent
-from plyngent.cli.display import render_events, set_verbose_tool_results
+from plyngent.cli.display import (
+    get_markdown_enabled,
+    markdown_render_available,
+    print_markdown,
+    render_events,
+    set_markdown_enabled,
+    set_verbose_tool_results,
+)
 from plyngent.lmproto.openai_compatible.model import ToolChatMessage
 
 if TYPE_CHECKING:
@@ -20,6 +27,7 @@ async def _aiter(events: list[AgentEvent]) -> AsyncIterator[AgentEvent]:
 
 
 async def test_render_reasoning_and_text(capsys: pytest.CaptureFixture[str]) -> None:
+    set_markdown_enabled(False)
     await render_events(
         _aiter(
             [
@@ -33,12 +41,14 @@ async def test_render_reasoning_and_text(capsys: pytest.CaptureFixture[str]) ->
     assert "think" in out
     assert "assistant: " in out
     assert "hello" in out
+    set_markdown_enabled(True)
 
 
 async def test_tool_result_preview_vs_verbose(capsys: pytest.CaptureFixture[str]) -> None:
     long = "x" * 200
     msg = ToolChatMessage(content=long, tool_call_id="1")
     set_verbose_tool_results(False)
+    set_markdown_enabled(False)
     await render_events(_aiter([ToolResultEvent(message=msg)]))
     out = capsys.readouterr().out
     assert "…" in out
@@ -49,3 +59,49 @@ async def test_tool_result_preview_vs_verbose(capsys: pytest.CaptureFixture[str]
     out2 = capsys.readouterr().out
     assert long in out2
     set_verbose_tool_results(False)
+    set_markdown_enabled(True)
+
+
+async def test_markdown_off_keeps_plain_stream(
+    capsys: pytest.CaptureFixture[str],
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    monkeypatch.setattr("plyngent.cli.display.markdown_render_available", lambda: True)
+    set_markdown_enabled(False)
+    await render_events(_aiter([TextDeltaEvent(content="**bold**")]))
+    out = capsys.readouterr().out
+    assert "**bold**" in out
+    set_markdown_enabled(True)
+
+
+async def test_markdown_on_replaces_with_rich(
+    capsys: pytest.CaptureFixture[str],
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    monkeypatch.setattr("plyngent.cli.display.markdown_render_available", lambda: True)
+    set_markdown_enabled(True)
+    await render_events(_aiter([TextDeltaEvent(content="hello **world**")]), markdown=True)
+    out = capsys.readouterr().out
+    # Rich markdown renders emphasis; raw ** markers should not remain as the sole form.
+    assert "assistant:" in out or "assistant: " in out
+    assert "world" in out
+
+
+def test_print_markdown_renders(capsys: pytest.CaptureFixture[str]) -> None:
+    print_markdown("# Title\n\n`code`", label="assistant: ")
+    out = capsys.readouterr().out
+    assert "Title" in out
+    assert "code" in out
+
+
+def test_markdown_flags_roundtrip() -> None:
+    set_markdown_enabled(False)
+    assert get_markdown_enabled() is False
+    set_markdown_enabled(True)
+    assert get_markdown_enabled() is True
+
+
+def test_markdown_render_available_respects_plain_env(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setenv("PLYNGENT_PLAIN", "1")
+    assert markdown_render_available() is False
+    monkeypatch.delenv("PLYNGENT_PLAIN", raising=False)