feat: treat disputed extracted values as unverified in constructability and critic prompts

backend/prompts.py

@@ -410,6 +410,9 @@ What is NOT a conflict:
 - Anything not supported with drawing evidence.
 Be conservative:
 - Only flag genuine disagreements.
+- When a value is marked DISPUTED (possible extraction misread), verify it against
+  the sheet images before relying on either reading; if the images do not resolve
+  it, do not assert a conflict from one reading alone.
 - A clean cluster with no contradiction must return an empty conflicts array.
 - missing_element requires evidence that another discipline would reasonably be expected to show the missing item.
 For each conflict:
@@ -545,6 +548,12 @@ Flag:
 Rules:
 - Only flag issues supported by drawing evidence.
 - Be specific about the location and why it is a constructability risk.
+- Assertions are machine-extracted from sheet images and may contain misread values,
+  especially quantities and member sizes (e.g. "(2) 2x6" vs "(5) 2x6").
+- When the cluster lists disputed_attributes, or two evidence items disagree on a
+  numeric value, do NOT assert a buildability conclusion from one reading. Report the
+  ambiguity itself (category "detail_gap", confidence "low") and state that the value
+  needs verification against the sheet.
 - Use plain ASCII only.
 Respond only with valid JSON."""
 
@@ -554,7 +563,8 @@ Respond ONLY with a valid JSON object - no markdown fences, no explanation:
 If no constructability issues are found, return: { "issues": [] }
 Extracted assertions: {assertions}
 Clusters: {clusters}
-Cross-discipline conflicts already found: {conflicts}"""
+Cross-discipline conflicts already found: {conflicts}
+Disputed extracted values in this cluster (possible vision misreads - treat as unverified): {disputes}"""
 
 
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