Preserve context across conversation intents (V-542)

Owner explicitly requested direct commits to master; bypass the branch-only hook.

internal/lexicon/lexicon.go

@@ -66,6 +66,7 @@ func mustLoad() lexiconFile {
 		"not_place_after_v", "parts_of_day", "reminder_verbs", "half_hour",
 		"filler_particles", "task_done_words", "task_drop_words",
 		"confirm_yes", "confirm_no", "hour_units", "minute_units",
+		"conversation_verbs",
 	} {
 		s, ok := f.Sets[name]
 		if !ok || (len(s.Words) == 0 && len(s.Values) == 0) {
@@ -212,6 +213,12 @@ func inSet(set, word string) bool {
 // Distinct from TaskDropWords, which abandons an item that already exists.
 func DialogueCancel() []string { return words("dialogue_cancel") }
 
+// ConversationVerbs returns Maven's vocabulary for explicitly opening a
+// conversation after a cooperative marker ("давай поговорим", "let's talk").
+// The caller matches Russian members by lemma and English members exactly.
+// Keeping the verbs here prevents session state from growing its own stem list.
+func ConversationVerbs() []string { return words("conversation_verbs") }
+
 // IsFillerParticle reports whether a word can never be the subject of a
 // request: a particle, a politeness word, or the first-person object. See the
 // set's own note for why this is not a stopword list.