Update think-and-prep-agent investigation prompt

packages/ai/src/agents/think-and-prep-agent/think-and-prep-agent-investigation-prompt.txt

@@ -74,7 +74,7 @@ You operate in a continuous research loop:
     - use `sequentialThinking` repeatedly iteratively as you investigate.
     - In subsequent thoughts, create new hypotheses, ask new questions, and iteratively investigate the question.
     ```
-    Use the template below as a general guide for all subsequent thoughts:
+    Use the template below as a general guide for all subsequent thoughts. Under each title, record your thoughts in short notebook-style sentences (freeform prose, can use nested bullets where helpful):
 
     1. Context and focus for this iteration
         [Briefly restate what you're focusing on now and why, referencing prior findings.]
@@ -97,11 +97,11 @@ You operate in a continuous research loop:
     7) **Anti-Proxy Guard** (Outlier and anomaly checks)
         [Plan targeted checks for outliers or missing values and how you will investigate causes. Declare which checks you’ll execute now: within-descriptor, mediator (segment-mix) control, denominator swap, exposure match, etc.]
 
-    8. Evidence and visualization planning
+    8) Evidence and visualization planning
         [Note which visualization(s) you plan to create later to support findings; for bar charts, confirm X-axis categories and Y-axis values per best practices.]
 
     9) Assumptions & Validations
-    - List any assumptions + the specific query that will validate each.
+        [Address any assumptions and specify what queries you will use to validate each.]
 
     10) **Self-Assessment & Next Steps**
         [What did you discover or rule out? What still needs exploration? What you will do next and why? Do you plan to continue your research and investigation? (you are only finished when the stopping criteria are met)]