diff --git a/.github/workflows/score.yml b/.github/workflows/score.yml
index 7e78bfa..14c5799 100644
--- a/.github/workflows/score.yml
+++ b/.github/workflows/score.yml
@@ -12,6 +12,12 @@ on:
 env:
   FORCE_JAVASCRIPT_ACTIONS_TO_NODE24: true
 
+# Serialize full-score jobs to avoid concurrent DB writes overwhelming the API.
+# Pending runs wait; they do NOT cancel each other (each merged agent must be scored).
+concurrency:
+  group: score-main
+  cancel-in-progress: false
+
 jobs:
   find-agent:
     runs-on: ubuntu-latest
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 07b588d..dfc6b96 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -28,10 +28,11 @@ def generate(spec: dict, llm: LLMClient) -> bytes:
     ...
 ```
 
-The harness injects `LLMClient` — no API key required. Whitelisted models: `claude-haiku-4-5`, `claude-3-5-haiku`, `gpt-4o-mini`. Both parameters are required; agents that omit `llm` are rejected at eval time.
+The harness injects `LLMClient` — no API key required. Whitelisted models: `anthropic/claude-haiku-4-5`, `anthropic/claude-3-5-haiku`, `openai/gpt-4o-mini`. Both parameters are required; agents that omit `llm` are rejected at eval time.
 
 Starting point in `examples/`:
-- `metric-aware-agent/` — adapts strategy per scoring metric, call `llm.chat()` to reason about geometry
+- `metric-aware-agent/` — adapts strategy per scoring metric; uses `llm.chat()` to reason about geometry
+- `llm-agent/` — minimal single-call LLM agent, good for getting started
 
 The agent runs inside a Docker container:
 - **Time:** 60 seconds | **Memory:** 4 GB | **Network:** enabled (LLM calls only)
diff --git a/agents/baseline/agent.py b/agents/baseline/agent.py
index c7e0cc9..687c7b2 100644
--- a/agents/baseline/agent.py
+++ b/agents/baseline/agent.py
@@ -29,15 +29,19 @@ def generate(spec: dict, llm: LLMClient) -> bytes:  # noqa: ARG001
     constraints = spec["constraints"]
     bolt_pattern = constraints["bolt_pattern_mm"]
     bolt_d = constraints["bolt_diameter_clearance_mm"]
+    bv = constraints["build_volume_mm"]  # [x, y, z] limits
+    load_pt = constraints["load_point_mm"]
 
     by_coords = [p[0] for p in bolt_pattern]
     bz_coords = [p[1] for p in bolt_pattern]
-    plate_y = max(by_coords) + 20.0
-    plate_z = max(bz_coords) + 20.0
+    # Clamp to build volume — leave 2mm margin to avoid floating-point boundary failures
+    plate_y = min(max(by_coords) + 20.0, bv[1] - 2.0)
+    plate_z = min(max(bz_coords) + 20.0, bv[2] - 2.0)
     plate_thickness = 10.0
 
-    shelf_length = constraints["load_point_mm"][0] + 15.0
-    shelf_thickness = 12.0
+    # Shelf must reach the load point in X and cover its Z coordinate
+    shelf_length = min(load_pt[0] + 15.0, bv[0] - 2.0)
+    shelf_thickness = min(max(15.0, load_pt[2] + 10.0), bv[2] - 2.0)
     shelf_z = plate_z
 
     # Mounting plate