fix(voice): stop backtick TTS crash and actually count error turns

Claude replies with markdown/backticks by default; MeloTTS's Korean text
normaliser has no entry for '`' and dies with KeyError: '`', so any reply
mentioning a command/code block crashed the whole voice turn (500 on
/api/voice-turn). Fix at the shared synth() choke point with
normalize_for_speech(), which flattens code fences/inline code/links/markdown
and guarantees no backtick reaches the worker — covering both the dashboard
voice turn and the Discord speak() bridge. Also add a PERSONA line asking the
model to avoid markdown (belt-and-suspenders; the code strip is the real fix).

errors_total never moved for turn-level failures: it was only bumped by
log("error") events, and the dashboard voice path calls turn.finish(error=...)
without logging. Emit one error-level log event from Turn.finish() when a turn
ends in error, so both the server counter and the browser SSE mirror stay
consistent, guarded to count at most once. Drop the now-redundant pipeline
log("error") to avoid double counting and remove the dead _publish stub.

Verified: raw backtick -> worker KeyError '`' reproduced; after fix real
MeloTTS synth of a backtick+fenced reply succeeds; /api/voice-turn returns 200
with a wav body on a backtick reply and errors_total stays 0, and an induced
synth failure returns 500 with errors_total incrementing to exactly 1. Full
suite 18 passed.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tests/test_monitor.py

@@ -72,6 +72,30 @@ def test_monitor_marks_errors():
     assert snap["status"]["errors_total"] >= 1
 
 
+def test_error_turn_increments_errors_total_once():
+    """The dashboard voice turn (dashboard.voice_turn) records a turn and calls
+    turn.finish(error=...) directly — it never goes through the pipeline's
+    log("error") path. That failure must still land in errors_total, and exactly
+    once no matter how many times the turn is re-published."""
+    mon = Monitor()
+    turn = mon.turn(source="discord")
+    turn.heard("`코드` 얘기")           # touches/publishes again
+    turn.replied("답변")                 # and again
+    assert mon.status_snapshot()["errors_total"] == 0
+
+    turn.finish(error="melo synth failed: KeyError '`'")
+    assert mon.status_snapshot()["errors_total"] == 1
+
+    # A stray re-finish/re-publish must not double count.
+    turn.finish(error="melo synth failed: KeyError '`'")
+    turn._touch()
+    assert mon.status_snapshot()["errors_total"] == 1
+
+    # The failure is also visible as an error-level event for the live feed.
+    events = mon.snapshot()["events"]
+    assert any(e["type"] == "log" and e["level"] == "error" for e in events)
+
+
 def test_subscriber_receives_live_turn_events():
     async def go():
         mon = Monitor()

tests/test_textnorm.py

@@ -0,0 +1,39 @@
+"""TTS input normalisation. Claude speaks in markdown/backticks; MeloTTS's
+Korean normaliser crashes on a bare backtick (``KeyError: '`'``), which used to
+take down the whole voice turn. normalize_for_speech() must strip formatting and
+above all guarantee no backtick reaches the synthesiser."""
+
+from wsai.backends.melo import normalize_for_speech
+
+
+def test_backticks_are_always_removed():
+    # The exact crash trigger: inline code, a fenced block, and a stray backtick.
+    reply = "`ls -la` 를 써봐. 예시:\n```python\nprint('hi')\n```\n그리고 ` 이건 홀로 남은 백틱"
+    out = normalize_for_speech(reply)
+    assert "`" not in out            # the character that crashes MeloTTS is gone
+    assert "ls -la" in out           # inner words are kept, just unwrapped
+    assert "print('hi')" in out      # fenced code content survives as spoken text
+
+
+def test_markdown_structure_flattened():
+    reply = "# 제목\n- 첫째 항목\n- 둘째 항목\n**굵게** 그리고 _기울임_\n> 인용문"
+    out = normalize_for_speech(reply)
+    assert "#" not in out
+    assert "**" not in out and "_" not in out
+    assert not out.lstrip().startswith(("-", ">"))
+    assert "첫째 항목" in out and "굵게" in out and "인용문" in out
+
+
+def test_links_reduced_to_label():
+    out = normalize_for_speech("자세히는 [문서](https://example.com/docs) 참고해")
+    assert "문서" in out
+    assert "http" not in out and "]" not in out and "(" not in out
+
+
+def test_plain_text_is_left_intact():
+    plain = "안녕, 지금 화면 잘 보고 있어. 뭐 도와줄까?"
+    assert normalize_for_speech(plain) == plain
+
+
+def test_empty_is_safe():
+    assert normalize_for_speech("") == ""