Set default concurrency to 1

src/haiku/rag/app.py

@@ -90,7 +90,7 @@ class HaikuRAGApp:
         question: str,
         max_iterations: int = 3,
         confidence_threshold: float = 0.8,
-        max_concurrency: int = 3,
+        max_concurrency: int = 1,
         verbose: bool = False,
     ):
         """Run research via the pydantic-graph pipeline (default)."""

src/haiku/rag/cli.py

@@ -256,7 +256,7 @@ def research(
         help="Minimum confidence (0-1) to stop",
     ),
     max_concurrency: int = typer.Option(
-        3,
+        1,
         "--max-concurrency",
         help="Max concurrent searches per iteration (planned)",
     ),

src/haiku/rag/research/state.py

@@ -20,6 +20,6 @@ class ResearchState:
     sub_questions: list[str] = field(default_factory=list)
     iterations: int = 0
     max_iterations: int = 3
-    max_concurrency: int = 3
+    max_concurrency: int = 1
     confidence_threshold: float = 0.8
     last_eval: EvaluationResult | None = None