Merge pull request 'Release v1.11.0: PWA install + code-only PWA login + email/metrics fixes' (#187) from development into master

.gitea/workflows/ci.yaml

@@ -252,7 +252,6 @@ jobs:
         run: |
           go run ./backend/cmd/dictgen -dawg-dir "${GITHUB_WORKSPACE}/dawg" -out /tmp/dictgold
           go run ./backend/cmd/validategen -dawg-dir "${GITHUB_WORKSPACE}/dawg" -out /tmp/validgold
-          go run ./backend/cmd/movegen -dawg-dir "${GITHUB_WORKSPACE}/dawg" -out /tmp/movegold
 
       - name: Set up Node
         uses: actions/setup-node@v4
@@ -272,7 +271,6 @@ jobs:
           DICT_DAWG_DIR: ${{ github.workspace }}/dawg
           DICT_GOLD_DIR: /tmp/dictgold
           DICT_VALID_DIR: /tmp/validgold
-          DICT_MOVEGEN_DIR: /tmp/movegold
         run: pnpm exec vitest run src/lib/dict/
 
   # gate is the single branch-protection required check. It always runs and passes

backend/cmd/movegen/main.go

@@ -1,374 +0,0 @@
-// Command movegen emits golden conformance fixtures for the client-side move
-// generator port (ui/src/lib/dict). It is a dev tool, run by hand; its output is
-// committed so the TypeScript parity tests run without a Go toolchain.
-//
-// For each small sample dictionary (English and Russian — the latter reaches
-// alphabet index 32, exercising the 33-letter cross-set boundary) it writes:
-//
-//   - sample_<tag>.dawg           the serialized dictionary (the reader/cursor fixture)
-//   - sample_<tag>.words.json     the stored words + their alphabet indexes
-//   - sample_<tag>.gen.json       ranked move-generation results from the real solver,
-//     for a handful of positions, plus the ruleset the TS
-//     side rebuilds to score identically
-//
-// Positions are built with only the solver's public API: an empty board, and
-// two-ply positions reached by applying the solver's own top move (so no internal
-// encoding is needed). Regenerate with:
-//
-//	go run ./backend/cmd/movegen -out ui/src/lib/dict/testdata
-package main
-
-import (
-	"bytes"
-	"encoding/json"
-	"flag"
-	"log"
-	"os"
-	"path/filepath"
-
-	"gitea.iliadenisov.ru/developer/scrabble-solver/board"
-	"gitea.iliadenisov.ru/developer/scrabble-solver/rack"
-	"gitea.iliadenisov.ru/developer/scrabble-solver/rules"
-	"gitea.iliadenisov.ru/developer/scrabble-solver/scrabble"
-	dawg "github.com/iliadenisov/dafsa"
-)
-
-// sampleWordsEN is the English sample dictionary, in strictly increasing
-// alphabet-index order (the builder requires it). Shared prefixes (car/care/cars),
-// shared suffixes (cats/dogs), internal-final nodes (do, an) and a one-letter word.
-var sampleWordsEN = []string{
-	"a", "an", "and", "ant",
-	"car", "care", "cared", "cares", "cars", "cat", "cats",
-	"do", "doe", "does", "dog", "dogs", "done", "dot",
-}
-
-// sampleWordsRU is the Russian sample dictionary, in strictly increasing index
-// order. It deliberately includes words starting with я (index 32) so the ported
-// cross-set handles alphabet indexes past JS's 31-bit shift boundary.
-var sampleWordsRU = []string{"ад", "ар", "оса", "я", "яд", "яр"}
-
-// sampleFixture is the JSON committed with the .dawg so the TypeScript cursor test
-// knows the exact word set (as alphabet indexes) to expect from enumeration.
-type sampleFixture struct {
-	Alphabet string   `json:"alphabet"`
-	NumAdded int      `json:"numAdded"`
-	Words    []string `json:"words"`
-	Indexes  [][]int  `json:"indexes"`
-}
-
-// genFixture is the move-generation golden set for one sample dictionary.
-type genFixture struct {
-	Ruleset genRuleset `json:"ruleset"`
-	Cases   []genCase  `json:"cases"`
-}
-
-// genRuleset is the scoring data the TS side rebuilds so evaluate() matches the Go
-// solver: letter values, premium multipliers per square, the centre, rack size and bonus.
-type genRuleset struct {
-	Size       int     `json:"size"`
-	Cols       int     `json:"cols"`
-	Center     int     `json:"center"`
-	RackSize   int     `json:"rackSize"`
-	Bingo      int     `json:"bingo"`
-	Values     []int   `json:"values"`
-	LetterMult [][]int `json:"letterMult"`
-	WordMult   [][]int `json:"wordMult"`
-}
-
-// genTile is one placed tile (a board tile or a move placement).
-type genTile struct {
-	Row    int  `json:"row"`
-	Col    int  `json:"col"`
-	Letter int  `json:"letter"`
-	Blank  bool `json:"blank"`
-}
-
-// genRack is a rack as a multiset of letter indexes plus a blank count.
-type genRack struct {
-	Letters []int `json:"letters"`
-	Blanks  int   `json:"blanks"`
-}
-
-// genMove is one ranked generated play: its orientation, placed tiles and total score.
-type genMove struct {
-	Dir   int       `json:"dir"`
-	Tiles []genTile `json:"tiles"`
-	Score int       `json:"score"`
-}
-
-// genCase is one generation position: the tiles already on the board (empty when
-// none), the rack, the mode/rule and the ranked moves the solver returns.
-type genCase struct {
-	Name             string    `json:"name"`
-	Placed           []genTile `json:"placed"`
-	Rack             genRack   `json:"rack"`
-	Mode             int       `json:"mode"`
-	IgnoreCrossWords bool      `json:"ignoreCrossWords"`
-	Moves            []genMove `json:"moves"`
-}
-
-func main() {
-	out := flag.String("out", "ui/src/lib/dict/testdata", "output directory for fixtures")
-	dawgDir := flag.String("dawg-dir", "", "when set, emit real-dictionary move-gen golden from the .dawg files in this dir (conformance mode) instead of the committed samples")
-	flag.Parse()
-
-	if err := os.MkdirAll(*out, 0o755); err != nil {
-		log.Fatalf("movegen: mkdir %s: %v", *out, err)
-	}
-
-	if *dawgDir != "" {
-		buildReal(*dawgDir, *out)
-		return
-	}
-
-	buildSample(*out, "en", rules.English(), sampleWordsEN, []genCase{
-		emptyCase("empty-cared", englishRack("caredts", 0), scrabble.Both, false),
-		emptyCase("empty-dogs", englishRack("dogsent", 0), scrabble.Both, false),
-		emptyCase("empty-blank", englishRack("caret", 1), scrabble.Both, false),
-		emptyCase("empty-single-word", englishRack("caredts", 0), scrabble.Both, true),
-	})
-
-	buildSample(*out, "ru", rules.RussianScrabble(), sampleWordsRU, []genCase{
-		emptyCase("empty-yad", russianRack("ядрасо", 0), scrabble.Both, false),
-	})
-}
-
-// buildSample writes the dawg, the word fixture and the generation golden set for
-// one sample dictionary. Two-ply cases are appended: the solver's own top move from
-// the first non-empty result is applied, then generation runs again on the new rack.
-func buildSample(out, tag string, rs *rules.Ruleset, words []string, cases []genCase) {
-	idx := rs.Alphabet
-	b := dawg.New(idx)
-	indexes := make([][]int, 0, len(words))
-	for _, w := range words {
-		if err := b.Add(w); err != nil {
-			log.Fatalf("movegen[%s]: add %q: %v", tag, w, err)
-		}
-		enc, err := idx.Encode(w)
-		if err != nil {
-			log.Fatalf("movegen[%s]: encode %q: %v", tag, w, err)
-		}
-		ints := make([]int, len(enc))
-		for i, x := range enc {
-			ints[i] = int(x)
-		}
-		indexes = append(indexes, ints)
-	}
-	finder := b.Finish()
-
-	writeJSON(filepath.Join(out, "sample_"+tag+".words.json"), sampleFixture{
-		Alphabet: tag, NumAdded: finder.NumAdded(), Words: words, Indexes: indexes,
-	})
-	dawgPath := filepath.Join(out, "sample_"+tag+".dawg")
-	if _, err := finder.Save(dawgPath); err != nil {
-		log.Fatalf("movegen[%s]: save %s: %v", tag, dawgPath, err)
-	}
-
-	s := scrabble.NewSolver(rs, finder)
-	for i := range cases {
-		runCase(s, rs, &cases[i], nil)
-	}
-	// A two-ply position from the first standard case that produced a move.
-	if two := twoPly(s, rs, cases); two != nil {
-		cases = append(cases, *two)
-	}
-
-	writeJSON(filepath.Join(out, "sample_"+tag+".gen.json"), genFixture{
-		Ruleset: rulesetOf(rs), Cases: cases,
-	})
-	log.Printf("movegen[%s]: %d words, %d cases", tag, finder.NumAdded(), len(cases))
-}
-
-// realVariant maps a shipped dictionary file to the ruleset that scores it and the racks
-// the conformance positions use. smallRack/blankRack keep the first-move (empty board)
-// lists bounded on a dense dictionary; fullRack drives a deep 7-tile mid-game position,
-// kept small by the anchors around the already-placed word.
-type realVariant struct {
-	file, variant, smallRack, blankRack, fullRack string
-	rs                                            *rules.Ruleset
-}
-
-// buildReal emits move-generation golden from the real shipped dictionaries in dawgDir —
-// the full alphabets and deep graphs the tiny samples cannot reach — one
-// <variant>.movegen.json per variant. Like the dictgen/validategen vectors it is
-// regenerated in CI and never committed, so it pins no dictionary version into the repo.
-func buildReal(dawgDir, out string) {
-	reals := []realVariant{
-		{"en_sowpods", "scrabble_en", "aine", "ain", "aeinrst", rules.English()},
-		{"ru_scrabble", "scrabble_ru", "аеин", "аен", "аеиноср", rules.RussianScrabble()},
-		{"ru_erudit", "erudit_ru", "аеин", "аен", "аеиноср", rules.Erudit()},
-	}
-	for _, v := range reals {
-		data, err := os.ReadFile(filepath.Join(dawgDir, v.file+".dawg"))
-		if err != nil {
-			log.Fatalf("movegen[%s]: read dawg: %v", v.variant, err)
-		}
-		finder, err := dawg.Read(bytes.NewReader(data), 0)
-		if err != nil {
-			log.Fatalf("movegen[%s]: parse dawg: %v", v.variant, err)
-		}
-		s := scrabble.NewSolver(v.rs, finder)
-
-		cases := []genCase{
-			emptyCase("first-move", encRack(v.rs, v.smallRack, 0), scrabble.Both, false),
-			emptyCase("first-move-blank", encRack(v.rs, v.blankRack, 1), scrabble.Both, false),
-		}
-		for i := range cases {
-			runCase(s, v.rs, &cases[i], nil)
-		}
-		// A deep 7-tile mid-game: place the top first move, then generate again. The
-		// anchors around the placed word bound the list while still exercising a full rack,
-		// deep left/right extension and wide cross-sets over the real graph.
-		full := encRack(v.rs, v.fullRack, 0)
-		b := board.New(v.rs.Rows, v.rs.Cols)
-		if m1 := s.GenerateMovesOpts(b, toRack(v.rs.Size(), full), scrabble.Both, scrabble.PlayOptions{}); len(m1) > 0 {
-			mid := genCase{Name: "mid-game", Rack: full, Mode: int(scrabble.Both)}
-			runCase(s, v.rs, &mid, tilesOf(m1[0].Tiles))
-			cases = append(cases, mid)
-		}
-
-		writeJSON(filepath.Join(out, v.variant+".movegen.json"), genFixture{Ruleset: rulesetOf(v.rs), Cases: cases})
-		total := 0
-		for _, c := range cases {
-			total += len(c.Moves)
-		}
-		_ = finder.Close()
-		log.Printf("movegen[%s]: %d cases, %d golden moves", v.variant, len(cases), total)
-	}
-}
-
-// encRack encodes a rack given as the variant's letters (plus a blank count) into the
-// index-based genRack the fixtures carry.
-func encRack(rs *rules.Ruleset, letters string, blanks int) genRack {
-	enc, err := rs.Alphabet.Encode(letters)
-	if err != nil {
-		log.Fatalf("movegen: encode rack %q: %v", letters, err)
-	}
-	idx := make([]int, len(enc))
-	for i, b := range enc {
-		idx[i] = int(b)
-	}
-	return genRack{Letters: idx, Blanks: blanks}
-}
-
-// runCase fills a case's Moves by generating on a board holding the given placed
-// tiles (nil = empty board).
-func runCase(s *scrabble.Solver, rs *rules.Ruleset, c *genCase, placed []genTile) {
-	bd := board.New(rs.Rows, rs.Cols)
-	for _, t := range placed {
-		bd.Set(t.Row, t.Col, cellByte(t.Letter, t.Blank))
-	}
-	c.Placed = placed
-	rk := toRack(rs.Size(), c.Rack)
-	moves := s.GenerateMovesOpts(bd, rk, scrabble.Mode(c.Mode), scrabble.PlayOptions{IgnoreCrossWords: c.IgnoreCrossWords})
-	c.Moves = movesOf(moves)
-}
-
-// twoPly reaches a mid-game position by applying the top move of the first standard
-// case that generated one, then generates again with a fresh rack of the same tiles.
-func twoPly(s *scrabble.Solver, rs *rules.Ruleset, cases []genCase) *genCase {
-	for _, c := range cases {
-		if c.IgnoreCrossWords || len(c.Moves) == 0 {
-			continue
-		}
-		placed := c.Moves[0].Tiles
-		next := genCase{Name: "two-ply", Rack: c.Rack, Mode: int(scrabble.Both)}
-		runCase(s, rs, &next, placed)
-		return &next
-	}
-	return nil
-}
-
-// cellByte encodes a board cell the way internal/encoding.Cell does (bits 0-5 hold
-// letter+1, bit 7 marks a blank). Duplicated here because that package is internal
-// to the solver module and cannot be imported.
-func cellByte(letter int, blank bool) byte {
-	v := byte(letter+1) & 0x3f
-	if blank {
-		v |= 0x80
-	}
-	return v
-}
-
-func toRack(size int, r genRack) rack.Rack {
-	rk := rack.New(size)
-	for _, l := range r.Letters {
-		rk.Add(byte(l))
-	}
-	for i := 0; i < r.Blanks; i++ {
-		rk.AddBlank()
-	}
-	return rk
-}
-
-func rulesetOf(rs *rules.Ruleset) genRuleset {
-	lm := make([][]int, rs.Rows)
-	wm := make([][]int, rs.Rows)
-	for r := 0; r < rs.Rows; r++ {
-		lm[r] = make([]int, rs.Cols)
-		wm[r] = make([]int, rs.Cols)
-		for c := 0; c < rs.Cols; c++ {
-			p := rs.Premium(r, c)
-			lm[r][c] = p.LetterMult()
-			wm[r][c] = p.WordMult()
-		}
-	}
-	return genRuleset{
-		Size: rs.Size(), Cols: rs.Cols, Center: rs.Center, RackSize: rs.RackSize,
-		Bingo: rs.Bingo, Values: rs.Values, LetterMult: lm, WordMult: wm,
-	}
-}
-
-func movesOf(ms []scrabble.Move) []genMove {
-	out := make([]genMove, len(ms))
-	for i, m := range ms {
-		out[i] = genMove{Dir: int(m.Dir), Tiles: tilesOf(m.Tiles), Score: m.Score}
-	}
-	return out
-}
-
-func tilesOf(ps []scrabble.Placement) []genTile {
-	out := make([]genTile, len(ps))
-	for i, p := range ps {
-		out[i] = genTile{Row: p.Row, Col: p.Col, Letter: int(p.Letter), Blank: p.Blank}
-	}
-	return out
-}
-
-// emptyCase builds an empty-board case (Moves filled later by runCase).
-func emptyCase(name string, r genRack, mode scrabble.Mode, ignoreCross bool) genCase {
-	return genCase{Name: name, Rack: r, Mode: int(mode), IgnoreCrossWords: ignoreCross}
-}
-
-// englishRack builds a rack from lowercase a-z letters (index = letter-'a').
-func englishRack(letters string, blanks int) genRack {
-	idx := make([]int, 0, len(letters))
-	for _, ch := range letters {
-		idx = append(idx, int(ch-'a'))
-	}
-	return genRack{Letters: idx, Blanks: blanks}
-}
-
-// russianRack builds a rack from the Russian sample letters used above.
-func russianRack(letters string, blanks int) genRack {
-	m := map[rune]int{'а': 0, 'д': 4, 'о': 15, 'р': 17, 'с': 18, 'я': 32}
-	idx := make([]int, 0, len([]rune(letters)))
-	for _, ch := range letters {
-		i, ok := m[ch]
-		if !ok {
-			log.Fatalf("movegen: russianRack: no index for %q", string(ch))
-		}
-		idx = append(idx, i)
-	}
-	return genRack{Letters: idx, Blanks: blanks}
-}
-
-func writeJSON(path string, v any) {
-	data, err := json.MarshalIndent(v, "", "  ")
-	if err != nil {
-		log.Fatalf("movegen: marshal %s: %v", path, err)
-	}
-	if err := os.WriteFile(path, append(data, '\n'), 0o644); err != nil {
-		log.Fatalf("movegen: write %s: %v", path, err)
-	}
-}

backend/internal/robot/strategyfixture_test.go

@@ -1,146 +0,0 @@
-package robot
-
-import (
-	"encoding/json"
-	"os"
-	"path/filepath"
-	"strconv"
-	"testing"
-
-	"scrabble/backend/internal/engine"
-)
-
-// The client-side offline robot (ui/src/lib/robot) reproduces the robot's move choice
-// so a local vs_ai game plays the same way as the server. These golden fixtures pin that
-// TS port to the real Go strategy. Being in-package, this emitter can exercise the
-// unexported mix / playToWin / deviates / selectMove that the port mirrors.
-
-type mixCase struct {
-	Seed  string `json:"seed"`
-	Salt  string `json:"salt"`
-	Nums  []int  `json:"nums"`
-	Value string `json:"value"` // the mix() uint64, as a decimal string (exceeds JS safe ints)
-}
-
-type decisionCase struct {
-	Seed       string `json:"seed"`
-	MoveCount  int    `json:"moveCount"`
-	MyScore    int    `json:"myScore"`
-	OppScore   int    `json:"oppScore"`
-	CandScores []int  `json:"candScores"`
-	RackLen    int    `json:"rackLen"`
-	BagLen     int    `json:"bagLen"`
-	PlayToWin  bool   `json:"playToWin"`
-	Win        bool   `json:"win"` // the per-turn intent after the deviate flip
-	Kind       string `json:"kind"`
-	Index      int    `json:"index"` // chosen candidate index for a play, else -1
-}
-
-type strategyFixture struct {
-	PlayToWinPercent int            `json:"playToWinPercent"`
-	Mix              []mixCase      `json:"mix"`
-	Decisions        []decisionCase `json:"decisions"`
-}
-
-// scenario is one selectMove situation exercised across several seeds.
-type scenario struct {
-	moveCount, myScore, oppScore, rackLen, bagLen int
-	cands                                         []int
-}
-
-// TestEmitStrategyFixtures regenerates ui/src/lib/robot/testdata/strategy.json. It is
-// gated by EMIT_STRATEGY_FIXTURES so a normal `go test` skips it; the committed output is
-// what the TS parity test consumes. Regenerate with:
-//
-//	EMIT_STRATEGY_FIXTURES=1 go test ./backend/internal/robot -run TestEmitStrategyFixtures
-func TestEmitStrategyFixtures(t *testing.T) {
-	if os.Getenv("EMIT_STRATEGY_FIXTURES") == "" {
-		t.Skip("set EMIT_STRATEGY_FIXTURES=1 to regenerate ui/src/lib/robot/testdata/strategy.json")
-	}
-
-	seeds := []int64{1, 42, -7, 1000003, 9999999999, 123456789, -123456789}
-
-	mixCases := []mixCase{}
-	addMix := func(seed int64, salt string, nums ...int) {
-		mixCases = append(mixCases, mixCase{
-			Seed:  strconv.FormatInt(seed, 10),
-			Salt:  salt,
-			Nums:  append([]int{}, nums...),
-			Value: strconv.FormatUint(mix(seed, salt, nums...), 10),
-		})
-	}
-	for _, sd := range seeds {
-		addMix(sd, "win")
-		addMix(sd, "deviate", 0)
-		addMix(sd, "deviate", 7)
-	}
-
-	scenarios := []scenario{
-		{3, 40, 55, 7, 20, []int{30, 12, 8}},   // behind, mid-game
-		{10, 120, 90, 7, 8, []int{25, 18, 5}},  // ahead, late
-		{1, 0, 0, 7, 30, []int{60, 30, 15, 7}}, // first move, big spread
-		{20, 200, 40, 5, 2, []int{50, 20}},     // big lead, bag near empty (no deviate)
-		{5, 30, 30, 7, 14, []int{20, 20, 20}},  // equal margins (tie-break)
-		{8, 50, 60, 7, 20, []int{}},            // no play, bag can refill -> exchange
-		{8, 50, 60, 3, 2, []int{}},             // no play, bag can't refill -> pass
-		{15, 300, 10, 7, 6, []int{80, 40, 10}}, // overshoots the band -> nearest to +30
-	}
-
-	decisions := []decisionCase{}
-	for _, sd := range seeds {
-		for _, sc := range scenarios {
-			cands := make([]engine.MoveRecord, len(sc.cands))
-			for i, s := range sc.cands {
-				cands[i] = engine.MoveRecord{Score: s, Player: i}
-			}
-			rack := make([]string, sc.rackLen)
-			for i := range rack {
-				rack[i] = "a"
-			}
-
-			ptw := playToWin(sd)
-			win := ptw
-			if deviates(sd, sc.moveCount, sc.bagLen) {
-				win = !win
-			}
-			d := selectMove(cands, sc.myScore, sc.oppScore, win, defaultBand, rack, sc.bagLen)
-
-			kind, index := "pass", -1
-			switch d.kind {
-			case decidePlay:
-				kind, index = "play", d.move.Player
-			case decideExchange:
-				kind = "exchange"
-			}
-
-			decisions = append(decisions, decisionCase{
-				Seed:       strconv.FormatInt(sd, 10),
-				MoveCount:  sc.moveCount,
-				MyScore:    sc.myScore,
-				OppScore:   sc.oppScore,
-				CandScores: append([]int{}, sc.cands...),
-				RackLen:    sc.rackLen,
-				BagLen:     sc.bagLen,
-				PlayToWin:  ptw,
-				Win:        win,
-				Kind:       kind,
-				Index:      index,
-			})
-		}
-	}
-
-	fx := strategyFixture{PlayToWinPercent: playToWinPercent, Mix: mixCases, Decisions: decisions}
-	dir := filepath.Join("..", "..", "..", "ui", "src", "lib", "robot", "testdata")
-	if err := os.MkdirAll(dir, 0o755); err != nil {
-		t.Fatalf("mkdir %s: %v", dir, err)
-	}
-	data, err := json.MarshalIndent(fx, "", "  ")
-	if err != nil {
-		t.Fatalf("marshal: %v", err)
-	}
-	path := filepath.Join(dir, "strategy.json")
-	if err := os.WriteFile(path, append(data, '\n'), 0o644); err != nil {
-		t.Fatalf("write %s: %v", path, err)
-	}
-	t.Logf("wrote %s (%d mix, %d decisions)", path, len(mixCases), len(decisions))
-}

ui/src/lib/dict/dawg.cursor.test.ts

@@ -1,68 +0,0 @@
-import { describe, it, expect } from 'vitest';
-import { readFileSync } from 'node:fs';
-import { Dawg } from './dawg';
-
-// The step-by-step DAWG cursor (root/final/next/arcs) is the primitive the move
-// generator walks. These fast unit tests pin it against a small committed sample
-// dictionary (backend/cmd/movegen); the full parity vs the Go solver lands with
-// the generator's conformance fixtures.
-const bytes = new Uint8Array(readFileSync(new URL('./testdata/sample_en.dawg', import.meta.url)));
-const fixture = JSON.parse(
-  readFileSync(new URL('./testdata/sample_en.words.json', import.meta.url), 'utf8'),
-) as { numAdded: number; words: string[]; indexes: number[][] };
-
-const key = (w: number[]): string => w.join(',');
-
-// enumerateWords walks the whole automaton depth-first, collecting the index path
-// at every accepting node — i.e. every stored word.
-function enumerateWords(d: Dawg): number[][] {
-  const out: number[][] = [];
-  const path: number[] = [];
-  const visit = (node: number): void => {
-    d.arcs(node, (label, dest, final) => {
-      path.push(label);
-      if (final) out.push(path.slice());
-      visit(dest);
-      path.pop();
-      return true;
-    });
-  };
-  if (d.final(d.root())) out.push([]);
-  visit(d.root());
-  return out;
-}
-
-describe('dawg cursor', () => {
-  it('parses the sample fixture', () => {
-    const d = new Dawg(bytes);
-    expect(d.numAdded).toBe(fixture.numAdded);
-  });
-
-  it('root is not an accepting state (the sample has no empty word)', () => {
-    const d = new Dawg(bytes);
-    expect(d.final(d.root())).toBe(false);
-  });
-
-  it('enumerates exactly the stored words', () => {
-    const d = new Dawg(bytes);
-    const got = enumerateWords(d).map(key).sort();
-    const want = fixture.indexes.map(key).sort();
-    expect(got).toEqual(want);
-  });
-
-  it('next walks a stored word to an accepting node and rejects a non-edge', () => {
-    const d = new Dawg(bytes);
-    let node = d.root();
-    for (const ch of [2, 0, 17, 4, 3]) {
-      // "cared"
-      node = d.next(node, ch);
-      expect(node).toBeGreaterThanOrEqual(0);
-    }
-    expect(d.final(node)).toBe(true);
-    // "care" (index [2,0,17,4]) is an internal accepting node on the way to "cared".
-    const care = [2, 0, 17, 4].reduce((n, ch) => d.next(n, ch), d.root());
-    expect(d.final(care)).toBe(true);
-    // No stored word starts with 'z' (index 25).
-    expect(d.next(d.root(), 25)).toBe(-1);
-  });
-});

ui/src/lib/dict/dawg.ts

@@ -95,85 +95,6 @@ export class Dawg {
     return this.indexOf(word) >= 0;
   }
 
-  // --- Step-by-step traversal (the move generator's primitive) ---------------
-  //
-  // A `Node` is a bit offset into the graph; 0 denotes the root (which resolves
-  // to firstNodeOffset). These mirror dafsa's traverse.go Cursor (Root/Final/
-  // Next/Arcs) over the same bitstream this reader already decodes, so the ported
-  // generator can drive the automaton one transition at a time. Single-threaded
-  // JS shares this reader's position across calls; every method re-seeks to its
-  // node on entry, and arcs brackets the callback with a save/restore, so nested
-  // use during a walk is safe. Mirrors dafsa (*Cursor).
-
-  /** root returns the start state of the automaton. */
-  root(): number {
-    return 0;
-  }
-
-  /** final reports whether node is an accepting state (a stored word ends there). */
-  final(node: number): boolean {
-    if (this.numEdges <= 0) {
-      return this.hasEmptyWord && node === 0;
-    }
-    this.p = node === 0 ? this.firstNodeOffset : node;
-    return this.readBits(1) === 1;
-  }
-
-  /**
-   * next follows the edge labelled ch (an alphabet index) from node, returning the
-   * destination node, or -1 when no such edge exists.
-   */
-  next(node: number, ch: number): number {
-    return this.getEdge(node, ch) ? this.eNode : -1;
-  }
-
-  /**
-   * arcs calls fn for each out-edge of node in ascending label order, passing the
-   * edge's label, its destination node and whether that destination is accepting.
-   * It stops early if fn returns false. Mirrors dafsa (*Cursor).Arcs.
-   */
-  arcs(node: number, fn: (label: number, dest: number, final: boolean) => boolean): void {
-    if (this.numEdges <= 0) {
-      return;
-    }
-    this.p = node === 0 ? this.firstNodeOffset : node;
-    this.readBits(1); // node final flag — not needed here
-    const fallthrough = this.readBits(1);
-
-    if (fallthrough === 1) {
-      const label = this.readBits(this.cbits);
-      // The reader now sits at the destination node, whose first bit is its final flag.
-      const dest = this.p;
-      const final = this.readBits(1) === 1;
-      fn(label, dest, final);
-      return;
-    }
-
-    const nskiplen = bitsLen(this.wbits);
-    let nskip = 0;
-    let numEdges = 1;
-    if (this.readBits(1) !== 1) {
-      // not a single edge
-      numEdges = this.readUnsigned();
-      nskip = this.readBits(nskiplen);
-    }
-
-    for (let i = 0; i < numEdges; i++) {
-      const label = this.readBits(this.cbits);
-      if (i > 0) {
-        this.readBits(nskip); // per-edge skip count, unused for traversal
-      }
-      const dest = this.readBits(this.abits);
-      const resume = this.p;
-      this.p = dest;
-      const final = this.readBits(1) === 1;
-      if (!fn(label, dest, final)) {
-        return;
-      }
-      this.p = resume;
-    }
-  }
-
   // getEdge resolves the outgoing edge for ch from the node at the given bit
   // offset. On success it fills eNode/eCount/eFinal and returns true. Mirrors
   // dafsa (*dawg).getEdge.

ui/src/lib/dict/generate.parity.test.ts

@@ -1,99 +0,0 @@
-import { describe, it, expect } from 'vitest';
-import { readFileSync } from 'node:fs';
-import { Dawg } from './dawg';
-import { generateMoves, GenRack, type GenBoard, type Mode } from './generate';
-import type { Ruleset } from './validate';
-
-// Conformance gate for the ported move generator: for each committed position it must
-// return exactly the ranked play list the real Go solver returns (backend/cmd/movegen).
-// The Russian sample reaches alphabet index 32, exercising the 33-letter cross-set.
-
-interface Tile {
-  row: number;
-  col: number;
-  letter: number;
-  blank: boolean;
-}
-interface GenMove {
-  dir: number;
-  tiles: Tile[];
-  score: number;
-}
-interface Fixture {
-  ruleset: {
-    size: number;
-    cols: number;
-    center: number;
-    rackSize: number;
-    bingo: number;
-    values: number[];
-    letterMult: number[][];
-    wordMult: number[][];
-  };
-  cases: {
-    name: string;
-    placed: Tile[] | null;
-    rack: { letters: number[]; blanks: number };
-    mode: number;
-    ignoreCrossWords: boolean;
-    moves: GenMove[];
-  }[];
-}
-
-function load(tag: string): { dawg: Dawg; fx: Fixture } {
-  const bytes = new Uint8Array(readFileSync(new URL(`./testdata/sample_${tag}.dawg`, import.meta.url)));
-  const fx = JSON.parse(
-    readFileSync(new URL(`./testdata/sample_${tag}.gen.json`, import.meta.url), 'utf8'),
-  ) as Fixture;
-  return { dawg: new Dawg(bytes), fx };
-}
-
-function buildBoard(placed: Tile[], cols: number): GenBoard {
-  const grid: ({ letter: number; blank: boolean } | null)[] = new Array(cols * cols).fill(null);
-  for (const t of placed) grid[t.row * cols + t.col] = { letter: t.letter, blank: t.blank };
-  const inBounds = (r: number, c: number): boolean => r >= 0 && r < cols && c >= 0 && c < cols;
-  return {
-    rows: cols,
-    cols,
-    inBounds,
-    filled: (r, c) => inBounds(r, c) && grid[r * cols + c] !== null,
-    cellAt: (r, c) => grid[r * cols + c]!,
-    isEmpty: () => placed.length === 0,
-  };
-}
-
-function rulesetFor(fx: Fixture, ignoreCrossWords: boolean): Ruleset {
-  const r = fx.ruleset;
-  return {
-    cols: r.cols,
-    center: r.center,
-    rackSize: r.rackSize,
-    bingo: r.bingo,
-    values: r.values,
-    letterMult: (row, col) => r.letterMult[row][col],
-    wordMult: (row, col) => r.wordMult[row][col],
-    ignoreCrossWords,
-  };
-}
-
-// sig is an order-stable signature of a move: orientation, score and its placed tiles
-// sorted by square — so two lists compare equal iff they rank the same plays the same way.
-function sig(m: GenMove): string {
-  const ts = m.tiles.slice().sort((a, b) => (a.row !== b.row ? a.row - b.row : a.col - b.col));
-  return `${m.dir}#${m.score}#` + ts.map((t) => `${t.row},${t.col},${t.letter}${t.blank ? '*' : ''}`).join(';');
-}
-
-for (const tag of ['en', 'ru']) {
-  describe(`move generator parity vs Go solver (${tag})`, () => {
-    const { dawg, fx } = load(tag);
-    for (const c of fx.cases) {
-      it(c.name, () => {
-        const board = buildBoard(c.placed ?? [], fx.ruleset.cols);
-        const rack = GenRack.from(fx.ruleset.size, c.rack.letters, c.rack.blanks);
-        const rs = rulesetFor(fx, c.ignoreCrossWords);
-        const got = generateMoves(dawg, board, rack, rs, c.mode as Mode);
-        expect(got.map(sig)).toEqual(c.moves.map(sig));
-      });
-    }
-  });
-}

ui/src/lib/dict/generate.realparity.test.ts

@@ -1,113 +0,0 @@
-import { describe, it, expect } from 'vitest';
-import { readFileSync, existsSync } from 'node:fs';
-import { join } from 'node:path';
-import { Dawg } from './dawg';
-import { generateMoves, GenRack, type GenBoard, type Mode } from './generate';
-import type { Ruleset } from './validate';
-
-// Full-dictionary conformance for the ported move generator: for positions over the real
-// shipped dictionaries (deep graphs and full 26/33-letter alphabets the tiny committed
-// samples cannot reach) it must return exactly the ranked list the Go solver does. The
-// golden vectors come from `go run ./backend/cmd/movegen -dawg-dir <dawg> -out <dir>` and
-// the CI conformance job wires the two directories in; the suite skips when they are unset.
-const dawgDir = process.env.DICT_DAWG_DIR;
-const goldDir = process.env.DICT_MOVEGEN_DIR;
-const ready = !!dawgDir && !!goldDir && existsSync(dawgDir) && existsSync(goldDir);
-
-// variant -> the release dawg file name (matches dawg.parity.test.ts / the movegen tool).
-const variants = [
-  { variant: 'scrabble_en', dawg: 'en_sowpods' },
-  { variant: 'scrabble_ru', dawg: 'ru_scrabble' },
-  { variant: 'erudit_ru', dawg: 'ru_erudit' },
-];
-
-interface Tile {
-  row: number;
-  col: number;
-  letter: number;
-  blank: boolean;
-}
-interface GenMove {
-  dir: number;
-  tiles: Tile[];
-  score: number;
-}
-interface Fixture {
-  ruleset: {
-    size: number;
-    cols: number;
-    center: number;
-    rackSize: number;
-    bingo: number;
-    values: number[];
-    letterMult: number[][];
-    wordMult: number[][];
-  };
-  cases: {
-    name: string;
-    placed: Tile[] | null;
-    rack: { letters: number[]; blanks: number };
-    mode: number;
-    ignoreCrossWords: boolean;
-    moves: GenMove[];
-  }[];
-}
-
-function buildBoard(placed: Tile[], cols: number): GenBoard {
-  const grid: ({ letter: number; blank: boolean } | null)[] = new Array(cols * cols).fill(null);
-  for (const t of placed) grid[t.row * cols + t.col] = { letter: t.letter, blank: t.blank };
-  const inBounds = (r: number, c: number): boolean => r >= 0 && r < cols && c >= 0 && c < cols;
-  return {
-    rows: cols,
-    cols,
-    inBounds,
-    filled: (r, c) => inBounds(r, c) && grid[r * cols + c] !== null,
-    cellAt: (r, c) => grid[r * cols + c]!,
-    isEmpty: () => placed.length === 0,
-  };
-}
-
-function rulesetFor(fx: Fixture, ignoreCrossWords: boolean): Ruleset {
-  const r = fx.ruleset;
-  return {
-    cols: r.cols,
-    center: r.center,
-    rackSize: r.rackSize,
-    bingo: r.bingo,
-    values: r.values,
-    letterMult: (row, col) => r.letterMult[row][col],
-    wordMult: (row, col) => r.wordMult[row][col],
-    ignoreCrossWords,
-  };
-}
-
-function sig(m: GenMove): string {
-  const ts = m.tiles.slice().sort((a, b) => (a.row !== b.row ? a.row - b.row : a.col - b.col));
-  return `${m.dir}#${m.score}#` + ts.map((t) => `${t.row},${t.col},${t.letter}${t.blank ? '*' : ''}`).join(';');
-}
-
-describe.skipIf(!ready)('move generator parity vs Go on the real dictionaries', () => {
-  for (const v of variants) {
-    describe(v.variant, () => {
-      // Guard the collection-time reads: the block is skipped when the dirs are unset, but
-      // the describe callback still runs to register tests, so touch the filesystem only
-      // when ready (otherwise join(undefined, …) would throw during a normal unit run).
-      if (!ready) return;
-      const fx = JSON.parse(readFileSync(join(goldDir!, `${v.variant}.movegen.json`), 'utf8')) as Fixture;
-      const dawg = new Dawg(new Uint8Array(readFileSync(join(dawgDir!, `${v.dawg}.dawg`))));
-      for (const c of fx.cases) {
-        it(
-          c.name,
-          () => {
-            const board = buildBoard(c.placed ?? [], fx.ruleset.cols);
-            const rack = GenRack.from(fx.ruleset.size, c.rack.letters, c.rack.blanks);
-            const rs = rulesetFor(fx, c.ignoreCrossWords);
-            const got = generateMoves(dawg, board, rack, rs, c.mode as Mode);
-            expect(got.map(sig)).toEqual(c.moves.map(sig));
-          },
-          60_000,
-        );
-      }
-    });
-  }
-});

ui/src/lib/dict/generate.ts

@@ -1,418 +0,0 @@
-// Local move generator: every legal play for a rack on a board, ranked by
-// descending score. Ported from the scrabble-solver engine — the Appel-Jacobson
-// two-phase algorithm (LeftPart then ExtendRight) over a plain left-to-right DAWG
-// (scrabble/gen_dawg.go, gen.go, crossset.go, solver.go, key.go). It walks the DAWG
-// with the cursor from dawg.ts and scores each play with evaluate() from validate.ts,
-// so the whole robot brain runs on-device. Faithfulness to the Go solver is pinned by
-// generate.parity.test.ts against golden fixtures (backend/cmd/movegen).
-//
-// Everything works in alphabet-index space, mirroring the Go engine. A letterSet is
-// a per-square cross-set (the letters that form a legal perpendicular word there);
-// it is a boolean membership array rather than a uint64, so alphabet indexes past
-// JS's 31-bit shift boundary (Russian has 33 letters) are handled exactly.
-
-import { Dawg } from './dawg';
-import {
-  evaluate,
-  connected,
-  Horizontal,
-  Vertical,
-  type Board,
-  type Ruleset,
-  type Move,
-  type Placement,
-  type Direction,
-} from './validate';
-
-/** Both generates across plays (on the board) and down plays (on its transpose). */
-export const Both = 0;
-/** OnlyHorizontal generates across plays only. */
-export const OnlyHorizontal = 1;
-/** OnlyVertical generates down plays only (Эрудит plays a single orientation per turn). */
-export const OnlyVertical = 2;
-export type Mode = typeof Both | typeof OnlyHorizontal | typeof OnlyVertical;
-
-function modeIncludes(mode: Mode, dir: Direction): boolean {
-  if (mode === Both) return true;
-  if (mode === OnlyHorizontal) return dir === Horizontal;
-  return dir === Vertical;
-}
-
-/**
- * GenBoard is the board view the generator needs: the validator's read view plus the
- * dimensions it iterates over. The whole board is square, so a transposed view (below)
- * satisfies the same shape.
- */
-export interface GenBoard extends Board {
-  rows: number;
-  cols: number;
-}
-
-/**
- * GenRack is a rack as per-letter tile counts plus a blank slot, mirroring
- * scrabble-solver/rack. The generator mutates a single rack in place — removing a
- * tile, recursing, putting it back — so the operations are O(1) and allocation-free.
- */
-export class GenRack {
-  private readonly counts: Int32Array;
-
-  /** Construct an empty rack for an alphabet of the given size (a trailing blank slot). */
-  constructor(size: number) {
-    this.counts = new Int32Array(size + 1);
-  }
-
-  /** from builds a rack from a multiset of letter indexes plus a blank count. */
-  static from(size: number, letters: readonly number[], blanks: number): GenRack {
-    const r = new GenRack(size);
-    for (const l of letters) r.counts[l]++;
-    r.counts[size] += blanks;
-    return r;
-  }
-
-  /** has reports whether at least one tile of the letter index is on the rack. */
-  has(letter: number): boolean {
-    return this.counts[letter] > 0;
-  }
-  /** blanks returns how many blank tiles are on the rack. */
-  blanks(): number {
-    return this.counts[this.counts.length - 1];
-  }
-  remove(letter: number): void {
-    this.counts[letter]--;
-  }
-  add(letter: number): void {
-    this.counts[letter]++;
-  }
-  removeBlank(): void {
-    this.counts[this.counts.length - 1]--;
-  }
-  addBlank(): void {
-    this.counts[this.counts.length - 1]++;
-  }
-  /** clone returns an independent copy. */
-  clone(): GenRack {
-    const c = new GenRack(this.counts.length - 1);
-    c.counts.set(this.counts);
-    return c;
-  }
-}
-
-// --- cross-sets ------------------------------------------------------------------
-//
-// A LetterSet is membership over alphabet letter indexes. Mirrors scrabble.letterSet
-// (a uint64) but as a Uint8Array so index 32 (Russian) is exact under JS bit ops.
-type LetterSet = Uint8Array;
-
-function fullSet(size: number): LetterSet {
-  return new Uint8Array(size).fill(1);
-}
-
-// walk follows word (alphabet indexes) left to right from the root; -1 if it derails.
-function walk(dawg: Dawg, word: readonly number[]): number {
-  let n = dawg.root();
-  for (const l of word) {
-    n = dawg.next(n, l);
-    if (n < 0) return -1;
-  }
-  return n;
-}
-
-// completers returns the letters X (< size) whose arc from state leads directly to an
-// accepting node — the deterministic cross-set primitive. Mirrors scrabble.completers.
-function completers(dawg: Dawg, state: number, size: number): LetterSet {
-  const set = new Uint8Array(size);
-  dawg.arcs(state, (label, _dest, final) => {
-    if (final && label < size) set[label] = 1;
-    return true;
-  });
-  return set;
-}
-
-// dawgCrossSet returns the letters X for which above·X·below is a stored word. Mirrors
-// scrabble.dawgCrossSet: a right extension (no tiles below) just completes the prefix
-// above; a left extension (tiles below) probes each X. above/below are letter indexes.
-function dawgCrossSet(dawg: Dawg, above: number[], below: number[], size: number): LetterSet {
-  if (above.length === 0 && below.length === 0) return fullSet(size);
-  if (below.length === 0) {
-    const node = walk(dawg, above);
-    if (node < 0) return new Uint8Array(size);
-    return completers(dawg, node, size);
-  }
-  let node = dawg.root();
-  if (above.length > 0) {
-    node = walk(dawg, above);
-    if (node < 0) return new Uint8Array(size);
-  }
-  const set = new Uint8Array(size);
-  for (let x = 0; x < size; x++) {
-    let m = dawg.next(node, x);
-    if (m < 0) continue;
-    let ok = true;
-    for (const l of below) {
-      m = dawg.next(m, l);
-      if (m < 0) {
-        ok = false;
-        break;
-      }
-    }
-    if (ok && dawg.final(m)) set[x] = 1;
-  }
-  return set;
-}
-
-// columnContext returns the contiguous run of filled cells immediately above and below
-// the empty square (r, c), each top to bottom, as letter indexes — the tiles a
-// perpendicular word through (r, c) would include. Mirrors scrabble.columnContext.
-function columnContext(b: GenBoard, r: number, c: number): { above: number[]; below: number[] } {
-  const above: number[] = [];
-  let start = r;
-  while (start - 1 >= 0 && b.filled(start - 1, c)) start--;
-  for (let rr = start; rr < r; rr++) above.push(b.cellAt(rr, c).letter);
-
-  const below: number[] = [];
-  let end = r;
-  while (end + 1 < b.rows && b.filled(end + 1, c)) end++;
-  for (let rr = r + 1; rr <= end; rr++) below.push(b.cellAt(rr, c).letter);
-  return { above, below };
-}
-
-// transpose returns a view of b with rows and columns swapped, so down-play generation
-// runs as across generation. Mirrors board.Transpose (as a lazy view).
-function transpose(b: GenBoard): GenBoard {
-  return {
-    rows: b.cols,
-    cols: b.rows,
-    inBounds: (r, c) => b.inBounds(c, r),
-    filled: (r, c) => b.filled(c, r),
-    cellAt: (r, c) => b.cellAt(c, r),
-    isEmpty: () => b.isEmpty(),
-  };
-}
-
-// A tentatively placed left-part tile; its column is fixed only at record time.
-interface TileInfo {
-  letter: number;
-  blank: boolean;
-}
-
-// AcrossGen carries one across-generation pass over a board. Mirrors scrabble.acrossGen.
-class AcrossGen {
-  private row = 0;
-  private readonly left: TileInfo[] = [];
-  private readonly right: Placement[] = [];
-
-  constructor(
-    private readonly dawg: Dawg,
-    private readonly bd: GenBoard,
-    private readonly rk: GenRack,
-    private readonly cross: (r: number, c: number) => LetterSet,
-    private readonly emit: (placements: Placement[]) => void,
-  ) {}
-
-  generateRow(row: number, firstMove: boolean, centerRow: number, centerCol: number): void {
-    this.row = row;
-    let limit = 0;
-    for (let col = 0; col < this.bd.cols; col++) {
-      if (this.bd.filled(row, col)) {
-        limit = 0;
-        continue;
-      }
-      const anchor = firstMove ? row === centerRow && col === centerCol : this.hasFilledNeighbor(row, col);
-      if (!anchor) {
-        limit++;
-        continue;
-      }
-      this.left.length = 0;
-      this.right.length = 0;
-      if (col > 0 && this.bd.filled(row, col - 1)) {
-        const pre = this.walkPrefix(row, col);
-        if (pre.ok) this.extendRight(pre.node, col, col);
-      } else {
-        this.leftPart(this.dawg.root(), col, limit);
-      }
-      limit = 0;
-    }
-  }
-
-  private hasFilledNeighbor(r: number, c: number): boolean {
-    return this.bd.filled(r - 1, c) || this.bd.filled(r + 1, c) || this.bd.filled(r, c - 1) || this.bd.filled(r, c + 1);
-  }
-
-  // walkPrefix walks the DAWG through the filled run ending at col-1, returning the
-  // node reached and whether that prefix exists. Mirrors scrabble.acrossGen.walkPrefix.
-  private walkPrefix(row: number, col: number): { node: number; ok: boolean } {
-    let start = col - 1;
-    while (start - 1 >= 0 && this.bd.filled(row, start - 1)) start--;
-    let node = this.dawg.root();
-    for (let c = start; c < col; c++) {
-      node = this.dawg.next(node, this.bd.cellAt(row, c).letter);
-      if (node < 0) return { node, ok: false };
-    }
-    return { node, ok: true };
-  }
-
-  // leftPart places left-part tiles from the rack (up to limit), calling extendRight
-  // after each prefix. Mirrors scrabble.acrossGen.leftPart.
-  private leftPart(node: number, anchorCol: number, limit: number): void {
-    this.extendRight(node, anchorCol, anchorCol);
-    if (limit === 0) return;
-    this.dawg.arcs(node, (label, dest) => {
-      if (this.rk.has(label)) {
-        this.rk.remove(label);
-        this.left.push({ letter: label, blank: false });
-        this.leftPart(dest, anchorCol, limit - 1);
-        this.left.pop();
-        this.rk.add(label);
-      }
-      if (this.rk.blanks() > 0) {
-        this.rk.removeBlank();
-        this.left.push({ letter: label, blank: true });
-        this.leftPart(dest, anchorCol, limit - 1);
-        this.left.pop();
-        this.rk.addBlank();
-      }
-      return true;
-    });
-  }
-
-  // extendRight extends the word rightward from col, placing rack tiles on empty
-  // squares (constrained by cross-sets) and following board tiles. A word is recorded
-  // only past the anchor. Mirrors scrabble.acrossGen.extendRight.
-  private extendRight(node: number, col: number, anchorCol: number): void {
-    if (col >= this.bd.cols) {
-      if (col > anchorCol && this.dawg.final(node)) this.record(anchorCol);
-      return;
-    }
-    if (this.bd.filled(this.row, col)) {
-      const dest = this.dawg.next(node, this.bd.cellAt(this.row, col).letter);
-      if (dest >= 0) this.extendRight(dest, col + 1, anchorCol);
-      return;
-    }
-
-    if (col > anchorCol && this.dawg.final(node)) this.record(anchorCol);
-    const cross = this.cross(this.row, col);
-    this.dawg.arcs(node, (label, dest) => {
-      if (cross[label] !== 1) return true;
-      if (this.rk.has(label)) {
-        this.rk.remove(label);
-        this.right.push({ row: this.row, col, letter: label, blank: false });
-        this.extendRight(dest, col + 1, anchorCol);
-        this.right.pop();
-        this.rk.add(label);
-      }
-      if (this.rk.blanks() > 0) {
-        this.rk.removeBlank();
-        this.right.push({ row: this.row, col, letter: label, blank: true });
-        this.extendRight(dest, col + 1, anchorCol);
-        this.right.pop();
-        this.rk.addBlank();
-      }
-      return true;
-    });
-  }
-
-  // record assembles the play (left part at fixed columns, then the right part) and
-  // reports it, skipping plays that lay no new tile. Mirrors scrabble.acrossGen.record.
-  private record(anchorCol: number): void {
-    if (this.left.length + this.right.length === 0) return;
-    const placements: Placement[] = [];
-    const leftStart = anchorCol - this.left.length;
-    for (let i = 0; i < this.left.length; i++) {
-      placements.push({ row: this.row, col: leftStart + i, letter: this.left[i].letter, blank: this.left[i].blank });
-    }
-    for (const p of this.right) placements.push(p);
-    this.emit(placements);
-  }
-}
-
-// runAcross generates all across plays on bd and reports each via emit in bd's
-// coordinates. Cross-sets are computed lazily (vertical words on bd) and cached.
-// Mirrors DAWGGenerator.runAcross.
-function runAcross(
-  dawg: Dawg,
-  bd: GenBoard,
-  rk: GenRack,
-  size: number,
-  rs: Ruleset,
-  centerRow: number,
-  centerCol: number,
-  emit: (placements: Placement[]) => void,
-): void {
-  let crossFn: (r: number, c: number) => LetterSet;
-  if (rs.ignoreCrossWords) {
-    const full = fullSet(size);
-    crossFn = () => full;
-  } else {
-    const cache = new Array<LetterSet | undefined>(bd.rows * bd.cols);
-    crossFn = (r, c) => {
-      const i = r * bd.cols + c;
-      let s = cache[i];
-      if (!s) {
-        const { above, below } = columnContext(bd, r, c);
-        s = dawgCrossSet(dawg, above, below, size);
-        cache[i] = s;
-      }
-      return s;
-    };
-  }
-
-  const ag = new AcrossGen(dawg, bd, rk, crossFn, emit);
-  const firstMove = bd.isEmpty();
-  for (let row = 0; row < bd.rows; row++) {
-    ag.generateRow(row, firstMove, centerRow, centerCol);
-  }
-}
-
-// moveKey is a canonical string identifying a play (direction plus its placed tiles),
-// used to de-duplicate and rank generated moves. Mirrors scrabble.moveKey.
-export function moveKey(dir: Direction, placements: readonly Placement[]): string {
-  const ps = placements.slice().sort((a, b) => (a.row !== b.row ? a.row - b.row : a.col - b.col));
-  let s = String(dir);
-  for (const p of ps) s += `;${p.row},${p.col},${p.letter}${p.blank ? '*' : ''}`;
-  return s;
-}
-
-/**
- * generateMoves returns every legal play for rack on board in the mode's orientations,
- * ranked by descending score (ties broken by the canonical move key). It walks the DAWG
- * with the cursor and scores each play with evaluate(); the alphabet size is taken from
- * the ruleset's value table. Mirrors (*Solver).GenerateMovesOpts (the ruleset carries
- * ignoreCrossWords for the single-word rule).
- */
-export function generateMoves(dawg: Dawg, board: GenBoard, rack: GenRack, rs: Ruleset, mode: Mode = Both): Move[] {
-  const size = rs.values.length;
-  const rk = rack.clone(); // generation mutates the rack in place and restores it
-  const centerRow = Math.floor(rs.center / rs.cols);
-  const centerCol = rs.center % rs.cols;
-
-  const moves: Move[] = [];
-  const seen = new Set<string>();
-  const emit = (dir: Direction, placements: Placement[]): void => {
-    const key = moveKey(dir, placements);
-    if (seen.has(key)) return;
-    const res = evaluate(board, rs, dir, placements);
-    if (res.err || !res.move) return;
-    seen.add(key);
-    moves.push(res.move);
-  };
-
-  if (modeIncludes(mode, Horizontal)) {
-    runAcross(dawg, board, rk, size, rs, centerRow, centerCol, (p) => emit(Horizontal, p));
-  }
-  if (modeIncludes(mode, Vertical)) {
-    const tb = transpose(board);
-    runAcross(dawg, tb, rk, size, rs, centerCol, centerRow, (p) => {
-      const rp = p.map((pl) => ({ row: pl.col, col: pl.row, letter: pl.letter, blank: pl.blank }));
-      emit(Vertical, rp);
-    });
-  }
-
-  const kept = moves.filter((m) => connected(board, rs, m));
-  kept.sort((a, b) => {
-    if (a.score !== b.score) return b.score - a.score;
-    const ka = moveKey(a.dir, a.tiles);
-    const kb = moveKey(b.dir, b.tiles);
-    return ka < kb ? -1 : ka > kb ? 1 : 0;
-  });
-  return kept;
-}

ui/src/lib/dict/testdata/sample_en.words.json

@@ -1,122 +0,0 @@
-{
-  "alphabet": "en",
-  "numAdded": 18,
-  "words": [
-    "a",
-    "an",
-    "and",
-    "ant",
-    "car",
-    "care",
-    "cared",
-    "cares",
-    "cars",
-    "cat",
-    "cats",
-    "do",
-    "doe",
-    "does",
-    "dog",
-    "dogs",
-    "done",
-    "dot"
-  ],
-  "indexes": [
-    [
-      0
-    ],
-    [
-      0,
-      13
-    ],
-    [
-      0,
-      13,
-      3
-    ],
-    [
-      0,
-      13,
-      19
-    ],
-    [
-      2,
-      0,
-      17
-    ],
-    [
-      2,
-      0,
-      17,
-      4
-    ],
-    [
-      2,
-      0,
-      17,
-      4,
-      3
-    ],
-    [
-      2,
-      0,
-      17,
-      4,
-      18
-    ],
-    [
-      2,
-      0,
-      17,
-      18
-    ],
-    [
-      2,
-      0,
-      19
-    ],
-    [
-      2,
-      0,
-      19,
-      18
-    ],
-    [
-      3,
-      14
-    ],
-    [
-      3,
-      14,
-      4
-    ],
-    [
-      3,
-      14,
-      4,
-      18
-    ],
-    [
-      3,
-      14,
-      6
-    ],
-    [
-      3,
-      14,
-      6,
-      18
-    ],
-    [
-      3,
-      14,
-      13,
-      4
-    ],
-    [
-      3,
-      14,
-      19
-    ]
-  ]
-}

ui/src/lib/dict/testdata/sample_ru.words.json

@@ -1,38 +0,0 @@
-{
-  "alphabet": "ru",
-  "numAdded": 6,
-  "words": [
-    "ад",
-    "ар",
-    "оса",
-    "я",
-    "яд",
-    "яр"
-  ],
-  "indexes": [
-    [
-      0,
-      4
-    ],
-    [
-      0,
-      17
-    ],
-    [
-      15,
-      18,
-      0
-    ],
-    [
-      32
-    ],
-    [
-      32,
-      4
-    ],
-    [
-      32,
-      17
-    ]
-  ]
-}

ui/src/lib/dict/validate.ts

@@ -297,9 +297,8 @@ export function validatePlay(
 }
 
 // connected reports whether the play connects to the position (or covers the
-// centre on the first move). Mirrors (*Solver).connected. Exported so the move
-// generator can apply the same post-generation connectivity filter.
-export function connected(b: Board, rs: Ruleset, m: Move): boolean {
+// centre on the first move). Mirrors (*Solver).connected.
+function connected(b: Board, rs: Ruleset, m: Move): boolean {
   if (b.isEmpty()) {
     const cr = Math.floor(rs.center / rs.cols);
     const cc = rs.center % rs.cols;

ui/src/lib/robot/strategy.parity.test.ts

@@ -1,68 +0,0 @@
-import { describe, it, expect } from 'vitest';
-import { readFileSync } from 'node:fs';
-import { mix, playToWin, deviates, decide, DEFAULT_BAND } from './strategy';
-
-// Conformance gate for the ported robot strategy: the client must fold the game seed and
-// choose its action exactly as backend/internal/robot/strategy.go does, so a local vs_ai
-// game plays the same. Golden fixtures come from the in-package emitter
-// (backend/internal/robot/strategyfixture_test.go).
-
-interface MixCase {
-  seed: string;
-  salt: string;
-  nums: number[];
-  value: string;
-}
-interface DecisionCase {
-  seed: string;
-  moveCount: number;
-  myScore: number;
-  oppScore: number;
-  candScores: number[];
-  rackLen: number;
-  bagLen: number;
-  playToWin: boolean;
-  win: boolean;
-  kind: string;
-  index: number;
-}
-interface Fixture {
-  playToWinPercent: number;
-  mix: MixCase[];
-  decisions: DecisionCase[];
-}
-
-const fx = JSON.parse(
-  readFileSync(new URL('./testdata/strategy.json', import.meta.url), 'utf8'),
-) as Fixture;
-
-describe('robot strategy parity vs Go', () => {
-  it('mix folds the seed like Go FNV-1a', () => {
-    for (const c of fx.mix) {
-      expect(mix(BigInt(c.seed), c.salt, ...c.nums), `${c.seed}/${c.salt}/${c.nums}`).toBe(BigInt(c.value));
-    }
-  });
-
-  it('chooses the same action as the Go robot', () => {
-    for (const c of fx.decisions) {
-      const seed = BigInt(c.seed);
-      const cands = c.candScores.map((score, index) => ({ score, index }));
-      const rack = new Array<string>(c.rackLen).fill('a');
-
-      expect(playToWin(seed), `playToWin ${c.seed}`).toBe(c.playToWin);
-
-      // the per-turn intent after the occasional off-strategy deviation
-      let win = playToWin(seed);
-      if (deviates(seed, c.moveCount, c.bagLen)) win = !win;
-      expect(win, `win ${c.seed}/${c.moveCount}/${c.bagLen}`).toBe(c.win);
-
-      const dec = decide(seed, c.moveCount, cands, c.myScore, c.oppScore, rack, c.bagLen, DEFAULT_BAND);
-      expect(dec.kind, `kind ${JSON.stringify(c)}`).toBe(c.kind);
-      if (dec.kind === 'play') {
-        expect(dec.move.index, `index ${JSON.stringify(c)}`).toBe(c.index);
-      } else if (dec.kind === 'exchange') {
-        expect(dec.exchange.length).toBe(c.rackLen);
-      }
-    }
-  });
-});

ui/src/lib/robot/strategy.ts

@@ -1,180 +0,0 @@
-// The offline robot's move choice, ported from backend/internal/robot/strategy.go so a
-// local vs_ai game plays exactly as the server robot does: it picks the candidate whose
-// resulting score margin lands closest to a target band (playing to win ~40% of games and
-// to lose the rest), with an occasional off-strategy "wobble" that fades as the bag empties.
-//
-// Everything derives deterministically from the game's bag seed, folded by FNV-1a (mix),
-// so the choice is reproducible. The 64-bit hash is computed with BigInt to stay bit-exact
-// with Go's uint64 arithmetic; faithfulness is pinned by strategy.parity.test.ts against
-// golden fixtures. Only the move-choice slice of strategy.go is ported — the server's
-// think-time, sleep-window and nudge scheduling are irrelevant to on-device play.
-
-// playToWinPercent is the probability, in percent, that the robot plays to win for a whole
-// game; the rest of the time it plays to lose, so the human wins about 60% of games.
-const playToWinPercent = 40;
-
-// deviateMaxProb is the peak probability of a single off-strategy move, held through the
-// opening and midgame; it tapers linearly to 0 over the last deviateTaperTiles bag tiles.
-const deviateMaxProb = 0.2;
-const deviateTaperTiles = 14;
-
-const FNV_OFFSET = 14695981039346656037n;
-const FNV_PRIME = 1099511628211n;
-const TWO_POW_64 = 1n << 64n;
-const MASK64 = TWO_POW_64 - 1n;
-
-// u64le returns the 8 little-endian bytes of v reduced mod 2^64, matching Go's
-// binary.LittleEndian.PutUint64(uint64(int64(v))) — negatives wrap two's-complement.
-function u64le(v: bigint): number[] {
-  let x = ((v % TWO_POW_64) + TWO_POW_64) % TWO_POW_64;
-  const out: number[] = [];
-  for (let i = 0; i < 8; i++) {
-    out.push(Number(x & 0xffn));
-    x >>= 8n;
-  }
-  return out;
-}
-
-/**
- * mix folds the game seed and a salt (a label plus optional integers such as the move
- * index) into a stable 64-bit value, mirroring robot.mix (FNV-1a over the seed's 8 bytes,
- * the salt bytes, then each number's 8 bytes). seed is the game's bag seed.
- */
-export function mix(seed: bigint, salt: string, ...nums: number[]): bigint {
-  let h = FNV_OFFSET;
-  const feed = (b: number): void => {
-    h = ((h ^ BigInt(b & 0xff)) * FNV_PRIME) & MASK64;
-  };
-  for (const b of u64le(seed)) feed(b);
-  for (let i = 0; i < salt.length; i++) feed(salt.charCodeAt(i));
-  for (const n of nums) for (const b of u64le(BigInt(n))) feed(b);
-  return h;
-}
-
-/** unitFloat maps a mixed value to a float in [0, 1), mirroring robot.unitFloat. */
-export function unitFloat(v: bigint): number {
-  return Number(v) / Number(TWO_POW_64);
-}
-
-/**
- * playToWin reports the robot's once-per-game decision to play to win, derived from the
- * seed so it is fixed for the whole game. Mirrors robot.playToWin.
- */
-export function playToWin(seed: bigint): boolean {
-  return mix(seed, 'win') % 100n < BigInt(playToWinPercent);
-}
-
-// deviateProb is the probability of a single off-strategy move given the tiles left in the
-// bag: deviateMaxProb through the midgame, tapering to 0 over the last deviateTaperTiles.
-function deviateProb(bagLen: number): number {
-  if (bagLen <= 0) return 0;
-  if (bagLen >= deviateTaperTiles) return deviateMaxProb;
-  return (deviateMaxProb * bagLen) / deviateTaperTiles;
-}
-
-/**
- * deviates reports whether the robot plays a single move against its per-game intent at
- * moveCount, given the tiles left in the bag — a deterministic per-turn draw, never firing
- * once the bag is empty. Mirrors robot.deviates.
- */
-export function deviates(seed: bigint, moveCount: number, bagLen: number): boolean {
-  const p = deviateProb(bagLen);
-  if (p <= 0) return false;
-  return unitFloat(mix(seed, 'deviate', moveCount)) < p;
-}
-
-/** MarginBand is an inclusive target range for the resulting score margin (own score after
- *  the move minus the opponent's). */
-export interface MarginBand {
-  lo: number;
-  hi: number;
-}
-
-/** DEFAULT_BAND aims to lead by 1..30 when playing to win (negated when playing to lose),
- *  matching robot.defaultBand. */
-export const DEFAULT_BAND: MarginBand = { lo: 1, hi: 30 };
-
-/**
- * Decision is the robot's chosen action: a play (the picked candidate), an exchange of the
- * listed tiles, or a pass. Generic over the candidate type (needs only a score) and the
- * rack tile type.
- */
-export type Decision<C, R> =
-  | { kind: 'play'; move: C }
-  | { kind: 'exchange'; exchange: R[] }
-  | { kind: 'pass' };
-
-// distanceToBand is how far m lies outside [lo, hi], or 0 when inside.
-function distanceToBand(m: number, lo: number, hi: number): number {
-  if (m < lo) return lo - m;
-  if (m > hi) return m - hi;
-  return 0;
-}
-
-/**
- * selectMove chooses the robot's action from the ranked candidate plays and the current
- * scores. With at least one legal play it picks the candidate whose resulting margin
- * (myScore + score - oppScore) is closest to the band (negated when not playing to win),
- * breaking ties toward the conservative edge (smallest lead when winning, smallest deficit
- * when losing). With no legal play it exchanges the whole rack when the bag can refill it,
- * else passes. Mirrors robot.selectMove.
- */
-export function selectMove<C extends { score: number }, R>(
-  cands: readonly C[],
-  myScore: number,
-  oppScore: number,
-  win: boolean,
-  band: MarginBand,
-  rack: readonly R[],
-  bagLen: number,
-): Decision<C, R> {
-  if (cands.length === 0) {
-    if (rack.length > 0 && bagLen >= rack.length) {
-      return { kind: 'exchange', exchange: [...rack] };
-    }
-    return { kind: 'pass' };
-  }
-
-  let lo = band.lo;
-  let hi = band.hi;
-  if (!win) {
-    lo = -band.hi;
-    hi = -band.lo;
-  }
-
-  const margin = (c: C): number => myScore + c.score - oppScore;
-  let best = 0;
-  let bestDist = Infinity;
-  for (let i = 0; i < cands.length; i++) {
-    const m = margin(cands[i]);
-    const dist = distanceToBand(m, lo, hi);
-    if (dist < bestDist) {
-      best = i;
-      bestDist = dist;
-    } else if (dist === bestDist) {
-      // Conservative tie-break: keep the lead (win) or the deficit (lose) small.
-      if ((win && m < margin(cands[best])) || (!win && m > margin(cands[best]))) best = i;
-    }
-  }
-  return { kind: 'play', move: cands[best] };
-}
-
-/**
- * decide is the robot's whole per-turn choice: the once-per-game play-to-win intent, flipped
- * for this move by the occasional deviation, fed to selectMove. Mirrors the decision slice of
- * robot (*Service).act. seed is the game's bag seed; cands are the ranked legal plays.
- */
-export function decide<C extends { score: number }, R>(
-  seed: bigint,
-  moveCount: number,
-  cands: readonly C[],
-  myScore: number,
-  oppScore: number,
-  rack: readonly R[],
-  bagLen: number,
-  band: MarginBand = DEFAULT_BAND,
-): Decision<C, R> {
-  let win = playToWin(seed);
-  if (deviates(seed, moveCount, bagLen)) win = !win;
-  return selectMove(cands, myScore, oppScore, win, band, rack, bagLen);
-}