weather asks the dictionary before guessing case (V-530)

locationCandidates reversed endings by hand to turn "в Казани" into the
nominative the geocoder wants. internal/morph knows the answer for the places
it has, so it goes first and the reversals stay behind it for the ones it does
not: "Твери" and "Перми" come back unchanged.

The four-rune floor was there to stop a two-letter stem, so it now tests the
stem instead. "Уфе" was under the floor and "Уфа" was never tried.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

CLAUDE.md

@@ -231,8 +231,10 @@ fact or a route is the defect; a regex over structured input — HTML, MIME, JSO
 argv list — is not. Before writing a Russian word list, pick one of these:
 
 - **`internal/lexicon`** — closed classes, in `lexicon_ru_v1.json`. Interrogatives,
-  capture verbs, cardinals, day offsets, weekdays, months, spoken hours. Editing a word is
+  capture verbs, reminder verbs, cardinals, day offsets, parts of day, weekdays, months,
-  a data change, and there is exactly one copy: months used to live in three files.
+  spoken hours. Editing a word is a data change, and there is exactly one copy: months used
+  to live in three files. Cardinals carry the oblique forms, because a spoken time declines
+  and `в семь` / `к семи` are one hour.
 - **`internal/morph`** — grammar, from the vendored golem Russian dictionary. `IsVerbForm`
   and `SameWord`. Note that lemma matching is BROADER than stem-plus-one-ending, so a verb
   slot that means the imperative must be matched exactly — `говори` and `говорил` are one

internal/weather/openmeteo.go

@@ -8,6 +8,9 @@ import (
 	"net/http"
 	"net/url"
 	"time"
+	"unicode"
+
+	"github.com/kami/maven/internal/morph"
 )
 
 type OpenMeteoProvider struct {
@@ -101,10 +104,20 @@ func (p *OpenMeteoProvider) CurrentWeather(ctx context.Context, location string)
 // sentence, in order. He says "какая погода в Казани", so the word arrives in
 // the prepositional case and the geocoder wants the nominative (Vikunja #421).
 //
-// Two cheap reversals cover most of what he says: a final "е" is usually a
+// The dictionary answers first (Vikunja #530). internal/morph lemmatises
-// nominative "а" (Москве → Москва) or nothing at all (Лондоне → Лондон), and a
+// "Уфе" to "Уфа" and "Москве" to "Москва", which is the same question this
-// final "и" is usually a soft sign (Казани → Казань). Indeclinable names —
+// used to guess at by reversing endings, asked of something that knows.
-// Тбилиси, Сочи, Осло — are already nominative and the first candidate answers.
+//
+// The reversals stay behind it, because the dictionary does not know every
+// place: "Твери" and "Перми" come back unchanged, and a final "и" is usually a
+// soft sign. A final "е" is usually a nominative "а" (Москве → Москва) or
+// nothing at all (Лондоне → Лондон). Indeclinable names — Тбилиси, Сочи, Осло —
+// are already nominative and the first candidate answers, which is why the word
+// as spoken is always tried before anything derived from it.
+//
+// There used to be a four-rune floor here, so "Уфе" was asked as spoken and
+// "Уфа" was never tried. The floor was there to stop a two-letter stem, and the
+// stem length is what it now tests.
 //
 // Nothing here is a guess about the weather: a wrong candidate finds no city
 // and the caller says so. It only decides which strings are worth asking about.
@@ -121,8 +134,9 @@ func locationCandidates(location string) []string {
 		}
 		out = append(out, s)
 	}
+	add(titleFirst(morph.Lemma(location)))
 	r := []rune(location)
-	if len(r) < 4 {
+	if len(r) < 3 {
 		return out
 	}
 	stem := string(r[:len(r)-1])
@@ -139,6 +153,17 @@ func locationCandidates(location string) []string {
 	return out
 }
 
+// titleFirst restores the leading capital a place name carries. morph.Lemma
+// answers lowercased, because a lemma is a dictionary entry and the dictionary
+// has no opinion about proper nouns.
+func titleFirst(s string) string {
+	r := []rune(s)
+	if len(r) == 0 {
+		return s
+	}
+	return string(unicode.ToUpper(r[0])) + string(r[1:])
+}
+
 func (p *OpenMeteoProvider) geocode(ctx context.Context, location string) (lat, lon float64, name string, err error) {
 	for _, cand := range locationCandidates(location) {
 		lat, lon, name, err = p.geocodeOne(ctx, cand)

internal/weather/openmeteo_test.go

@@ -86,14 +86,20 @@ func TestStubProvider(t *testing.T) {
 
 // TestLocationCandidates — he speaks the prepositional case and the geocoder
 // wants the nominative (Vikunja #421).
+//
+// The dictionary answers before the reversals now, so the nominative it knows
+// comes second and anything derived by hand follows (V-530). "Уфе" used to fall
+// under a four-rune floor and was asked as spoken, so "Уфа" was never tried.
 func TestLocationCandidates(t *testing.T) {
 	cases := map[string][]string{
 		"Москве":  {"Москве", "Москва", "Москв"},
 		"Казани":  {"Казани", "Казань", "Казан"},
-		"Лондоне": {"Лондоне", "Лондона", "Лондон"},
+		"Лондоне": {"Лондоне", "Лондон", "Лондона"},
 		"Тбилиси": {"Тбилиси", "Тбились", "Тбилис"},
 		"Berlin":  {"Berlin"},
-		"Уфе":     {"Уфе"}, // too short to strip — asked as spoken
+		"Уфе":     {"Уфе", "Уфа", "Уф"},
+		// The dictionary does not know it, so the soft-sign reversal answers.
+		"Твери": {"Твери", "Тверь", "Твер"},
 	}
 	for in, want := range cases {
 		got := locationCandidates(in)