Full Table — vary tense and verb family between consecutive prompts

randomFullTablePrompt now takes the previous prompt's tense and verb
ending and picks the next one to avoid an immediate repeat: when more
than one tense is selected the just-shown tense is excluded, and when
both -ar and -er/-ir verbs are available the next verb switches family.

Both constraints are best-effort — if honouring one would leave no
eligible fully-regular combo it is dropped, and the exhaustive
"anything eligible at all" guarantee is preserved.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Conjuga/Conjuga/Services/PracticeSessionService.swift

@@ -95,7 +95,16 @@ struct PracticeSessionService {
         return nil
     }
 
-    func randomFullTablePrompt() -> FullTablePrompt? {
+    /// Builds a Full Table prompt. `previousTenseId` / `previousEnding` describe
+    /// the prompt just shown; when possible the next prompt avoids repeating the
+    /// same tense back-to-back and switches the verb's ending family
+    /// (-ar ⇄ -er/-ir) so consecutive rounds feel varied. Both are best-effort:
+    /// if honouring them would leave no eligible combo, the constraint is
+    /// dropped rather than dead-ending.
+    func randomFullTablePrompt(
+        previousTenseId: String? = nil,
+        previousEnding: String? = nil
+    ) -> FullTablePrompt? {
         let settings = settings()
         // Full Table is testing the user's grasp of regular conjugation patterns,
         // not vocabulary recognition. Level filter is intentionally bypassed so
@@ -111,25 +120,29 @@ struct PracticeSessionService {
         let candidateTenseIds = settings.selectionTenseIDs
         guard !candidateTenseIds.isEmpty else { return nil }
 
-        // Cheap path: random sampling. With ~1750 verbs and several hundred
-        // fully-regular combos this almost always succeeds within a handful
-        // of attempts.
-        for _ in 0..<40 {
-            guard let verb = verbs.randomElement(),
-                  let tenseId = candidateTenseIds.randomElement(),
-                  let tenseInfo = TenseInfo.find(tenseId) else { continue }
-            if let prompt = makePromptIfFullyRegular(verb: verb, tenseId: tenseId, tenseInfo: tenseInfo) {
-                return prompt
-            }
+        let tenseChoices = tenseChoicesAvoidingRepeat(candidateTenseIds, previous: previousTenseId)
+        let verbChoices = verbChoicesSwitchingFamily(verbs, previousEnding: previousEnding)
+        let isConstrained = tenseChoices.count != candidateTenseIds.count
+            || verbChoices.count != verbs.count
+
+        // Best-effort: random-sample the constrained pool first so consecutive
+        // prompts vary the tense and the -ar/-er-ir family.
+        if isConstrained,
+           let prompt = sampleFullTablePrompt(verbs: verbChoices, tenseIds: tenseChoices) {
+            return prompt
+        }
+
+        // No constraint, or honouring it found nothing quickly — sample the
+        // full pool.
+        if let prompt = sampleFullTablePrompt(verbs: verbs, tenseIds: candidateTenseIds) {
+            return prompt
         }
 
         // Guarantee: if any eligible (verb, tense) combo exists in the data we
         // return one. Only return nil when the user's settings genuinely produce
         // an empty pool (so the UI can show an error state instead of a blank).
-        let shuffledVerbs = verbs.shuffled()
-        let shuffledTenseIds = candidateTenseIds.shuffled()
-        for verb in shuffledVerbs {
-            for tenseId in shuffledTenseIds {
+        for verb in verbs.shuffled() {
+            for tenseId in candidateTenseIds.shuffled() {
                 guard let tenseInfo = TenseInfo.find(tenseId) else { continue }
                 if let prompt = makePromptIfFullyRegular(verb: verb, tenseId: tenseId, tenseInfo: tenseInfo) {
                     return prompt
@@ -140,6 +153,39 @@ struct PracticeSessionService {
         return nil
     }
 
+    /// Random-sample up to 40 (verb, tense) pairs for a fully-regular combo.
+    /// With ~1750 verbs and several hundred eligible combos this almost always
+    /// succeeds within a handful of attempts.
+    private func sampleFullTablePrompt(verbs: [Verb], tenseIds: [String]) -> FullTablePrompt? {
+        guard !verbs.isEmpty, !tenseIds.isEmpty else { return nil }
+        for _ in 0..<40 {
+            guard let verb = verbs.randomElement(),
+                  let tenseId = tenseIds.randomElement(),
+                  let tenseInfo = TenseInfo.find(tenseId) else { continue }
+            if let prompt = makePromptIfFullyRegular(verb: verb, tenseId: tenseId, tenseInfo: tenseInfo) {
+                return prompt
+            }
+        }
+        return nil
+    }
+
+    /// Tense ids with the previous one removed — only when more than one tense
+    /// is selected and removing it still leaves a choice.
+    private func tenseChoicesAvoidingRepeat(_ ids: [String], previous: String?) -> [String] {
+        guard ids.count > 1, let previous else { return ids }
+        let filtered = ids.filter { $0 != previous }
+        return filtered.isEmpty ? ids : filtered
+    }
+
+    /// Verbs whose ending family (-ar vs -er/-ir) differs from the previous
+    /// verb's — only when both families are actually present in the pool.
+    private func verbChoicesSwitchingFamily(_ verbs: [Verb], previousEnding: String?) -> [Verb] {
+        guard let previousEnding else { return verbs }
+        let previousIsAr = (previousEnding == "ar")
+        let switched = verbs.filter { ($0.ending == "ar") != previousIsAr }
+        return switched.isEmpty ? verbs : switched
+    }
+
     /// Returns a `FullTablePrompt` if this verb's forms in the given tense
     /// follow the regular pattern (per `FullTableEligibility`). Nil otherwise.
     private func makePromptIfFullyRegular(

Conjuga/Conjuga/Views/Practice/FullTableView.swift

@@ -269,7 +269,10 @@ struct FullTableView: View {
             cloudContext: cloudModelContext,
             reflexiveBaseInfinitives: ReflexiveVerbStore.shared.baseInfinitives
         )
-        guard let prompt = service.randomFullTablePrompt() else {
+        guard let prompt = service.randomFullTablePrompt(
+            previousTenseId: currentTense?.id,
+            previousEnding: currentVerb?.ending
+        ) else {
             // Genuinely no eligible (verb, tense) combo. Surface a clear error
             // instead of a blank screen — the previous behaviour silently
             // rendered an empty header and inputs.