Add variable question distractor pools

README.md

@@ -32,6 +32,12 @@ The Godot client reads this from `project.godot`:
 step3/questions_api_url
 ```
 
+## Question Bank PDF Imports
+
+Use [QBANK_PDF_IMPORT_RUNBOOK.md](QBANK_PDF_IMPORT_RUNBOOK.md) for the complete
+OCR, original-authoring, validation, independent-review, reference-review, bulk
+insertion, production-verification, and cleanup workflow.
+
 ## Question Image Copyright Review
 
 All questions containing images must receive a copyright and licensing review
@@ -102,6 +108,22 @@ copyright requirements still apply. If the question schema does not expose a
 reference field, retain this information in the associated authoring or review
 record until it can be stored with the question.
 
+## Variable Distractor Pools
+
+Published questions may contain more than the five choices shown to a learner.
+The player always presents the correct answer plus four randomly selected
+distractors and keeps that set stable for the duration of the active session.
+Choice IDs are stable content identifiers; the A-E labels shown in the player
+are based on presentation order and must not be stored as answer analytics.
+
+Add only distractors that are plausible for the exact vignette while remaining
+unambiguously incorrect. Every added distractor requires its own explanation,
+stem-anchored wrong-answer follow-up, independent accuracy review, and
+authoritative reference coverage. There is no required number of additional
+distractors: record an exception instead of forcing a weak or co-correct
+answer. Do not expand production pools until the v2 exposure-statistics
+backfill metric reports completion.
+
 ## Duplicate Question Review
 
 Every question must be checked for duplicates before publication. This review