style: Address CodeRabbit nitpicks

- Add language specifier to markdown code blocks (MD040)
- Remove duplicate horizontal rule separator
- Use structured logging in fallback synthesis error handler
- Use _smart_truncate for completion messages (avoids unnecessary ellipsis)

docs/bugs/P2_ROUND_COUNTER_SEMANTIC_MISMATCH.md

@@ -13,7 +13,7 @@
 
 Progress display shows impossible values like "Round 11/5":
 
-```
+```text
 ⏱️ **PROGRESS**: Round 11/5 (~0s remaining)
 ```
 
@@ -57,7 +57,7 @@ In a multi-agent workflow with 4 agents (searcher, hypothesizer, judge, reporter
 ## Evidence From Logs
 
 The session showed this progression:
-```
+```text
 Round 1/5   - First agent completed
 Round 2/5   - Second agent completed
 Round 3/5   - Third agent completed
@@ -170,8 +170,6 @@ def test_progress_display_never_exceeds_max_rounds():
 
 ---
 
----
-
 ## Additional Issues Found During Analysis
 
 ### Issue 2: Dead Code - Unused `_get_progress_message` Method

src/orchestrators/advanced.py

@@ -264,7 +264,7 @@ The final output should be a structured research report."""
                 iteration=iteration,
             )
         except Exception as synth_error:
-            logger.error(f"{reason} synthesis failed", error=str(synth_error))
+            logger.error("Fallback synthesis failed", reason=reason, error=str(synth_error))
             yield AgentEvent(
                 type="complete",
                 message=f"Research completed. Synthesis failed: {synth_error}",
@@ -456,7 +456,7 @@ The final output should be a structured research report."""
 
         completion_event = AgentEvent(
             type=event_type,
-            message=f"{semantic_name}: {text_content[:200]}...",
+            message=f"{semantic_name}: {self._smart_truncate(text_content)}",
             iteration=iteration,
         )