chore(engine): pin 0.36.0; LESSON-FORMAT explains case_sensitive

docs/LESSON-FORMAT.md

@@ -172,6 +172,13 @@ right = card `back`). Requires non-empty `card_ids` and forbids an explicit
   "direction": "source_to_target" }
 ```
 
+Case is not an error. An exercise that teaches case (capitalisation)
+declares `"case_sensitive": true` (schema 1.19), and the app then grades
+it in case. No distractor may also be an accepted answer
+(`E-FREETEXT-DISJOINT`); they are compared without case unless the
+exercise declares `case_sensitive`, so `i am Anna` can be a distractor
+for `I am Anna` only there.
+
 ### cloze
 ```jsonc
 { "type": "cloze", "prompt": "…", "card_ids": [ … ],

schema/content-manifest.schema.json

@@ -481,5 +481,5 @@
   ],
   "title": "ContentManifest",
   "type": "object",
-  "x-schema-version": "1.18"
+  "x-schema-version": "1.19"
 }

schema/engine-version.txt

@@ -1 +1 @@
-0.35.0
+0.36.0

schema/lesson.schema.json

@@ -304,7 +304,7 @@
             }
           ],
           "default": null,
-          "description": "FREE_TEXT: list of accepted answers. Exact-match first, Levenshtein-tolerant fallback in the renderer. The first entry is the canonical answer shown after a wrong attempt. CLOZE ``multiselect`` (#1195) reuses this field with a mode-specific meaning: EVERY entry is a correct option (not just the first), rendered as a checkbox group with ``distractors`` and graded by exact-set match; the two lists must be disjoint.",
+          "description": "FREE_TEXT: list of accepted answers. Exact-match first, Levenshtein-tolerant fallback in the renderer; case is not an error unless ``case_sensitive`` is true. The first entry is the canonical answer shown after a wrong attempt. CLOZE ``multiselect`` (#1195) reuses this field with a mode-specific meaning: EVERY entry is a correct option (not just the first), rendered as a checkbox group with ``distractors`` and graded by exact-set match; the two lists must be disjoint.",
           "title": "Accept"
         },
         "accept_orderings": {
@@ -352,6 +352,12 @@
           "title": "Card Ids",
           "type": "array"
         },
+        "case_sensitive": {
+          "default": false,
+          "description": "FREE_TEXT: when true, an answer must match an ``accept`` entry in case (``I am Anna`` is right, ``i am Anna`` is wrong); when false (the default) case is not an error. Declare it only where the exercise teaches case, such as capitalisation. The rules follow it: ``accept`` and ``distractors`` are compared in case only when it is true (``E-FREETEXT-DISJOINT``). Schema 1.19, engine#242. Ignored by the other exercise types.",
+          "title": "Case Sensitive",
+          "type": "boolean"
+        },
         "cloze_mode": {
           "anyOf": [
             {
@@ -384,7 +390,7 @@
         },
         "distractors": {
           "default": [],
-          "description": "Content-only fallback distractors. The exercise renderer picks from this pool when no AI provider is configured (EXP-005 / P-114 dual mode). When AI is available, the AI generator may use the pool as a seed for harder distractors.",
+          "description": "Content-only fallback distractors. The exercise renderer picks from this pool when no AI provider is configured (EXP-005 / P-114 dual mode). When AI is available, the AI generator may use the pool as a seed for harder distractors. FREE_TEXT: no entry may also be an accepted answer (``E-FREETEXT-DISJOINT``, compared after trimming, in case only when ``case_sensitive`` is true).",
           "items": {
             "type": "string"
           },
@@ -1334,5 +1340,5 @@
   ],
   "title": "Lesson",
   "type": "object",
-  "x-schema-version": "1.18"
+  "x-schema-version": "1.19"
 }

schema/quality-rules.json

@@ -1,5 +1,5 @@
 {
-  "$schema-version": "1.18",
+  "$schema-version": "1.19",
   "_comment": "Shared quality minimums, canonical in learn-content-engine and applied by its validateLessonQuality (engine#185). A lesson's purpose lifts some of them: bridge the exercise and exercise-type minimums, quiz the exercise-type minimum. Consumers read these numbers from the pinned engine release instead of keeping a copy.",
   "rules": {
     "minExerciseTypes": 2,