Update docs with patient realism improvements

FIELD_NOTES.md

@@ -141,6 +141,18 @@ Priorité, and Bilan scores. Use plain text only.
 
 Without this reminder, the model often stayed in character and produced a patient-voice recap. That was both confusing and unusable for the learner.
 
+### 4b. Making the patient feel real
+
+Early versions of the prompt produced a patient who agreed with everything and never initiated. Every response was "D'accord" — technically correct but useless for practicing patient communication. Real patients ask questions, express concerns, and react to sensations.
+
+The fix was behavioral directives with probabilistic targets:
+- Patient must have mild dental anxiety and opinions about cost/procedures
+- Patient must ask questions, express concerns, or react unprompted in roughly 1 in 3 turns
+- Response length must vary: 1 word during active work, 2-3 sentences when initiating
+- Few-shot examples in the prompt show the desired style
+
+The key insight: listing behaviors ("ask questions") is not enough. The model needs concrete examples and probability targets to avoid collapsing into a single repetitive pattern. Adding a safety valve instruction ("if the conversation stalls, de-escalate and let the hygienist lead") prevents the patient from becoming uncooperative.
+
 ### 5. Edge cases that matter
 
 - **STT returns empty or too-short text** (< 2 chars). Show "Parlez plus fort ou plus longtemps" instead of sending garbage to the LLM.