test(offline): real-dictionary move-generator conformance in CI

Phase A (A4): prove the ported move generator (#188) against the FULL shipped
dictionaries, not just the tiny samples — the deep graphs and complete 26/33-letter
alphabets the samples cannot reach.

- backend/cmd/movegen: add a -dawg-dir mode that emits per-variant golden move-gen
  vectors from the real dawgs (a bounded first-move + a blank case + a deep 7-tile
  mid-game position). Regenerated in CI to /tmp, never committed (like the
  dictgen/validategen vectors), so no dictionary version is pinned into the repo.
- ui/src/lib/dict/generate.realparity.test.ts: env-gated (DICT_DAWG_DIR +
  DICT_MOVEGEN_DIR) parity against that golden — 9 positions across scrabble_en /
  scrabble_ru / erudit_ru match the Go solver exactly. Skips cleanly when unset.
- .gitea/workflows/ci.yaml: the conformance job now generates the movegen golden
  and points the gated vitest at it (DICT_MOVEGEN_DIR).

.gitea/workflows/ci.yaml

@@ -252,6 +252,7 @@ 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
@@ -271,6 +272,7 @@ 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

@@ -19,6 +19,7 @@
 package main
 
 import (
+	"bytes"
 	"encoding/json"
 	"flag"
 	"log"
@@ -108,12 +109,18 @@ type genCase struct {
 
 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),
@@ -172,6 +179,78 @@ func buildSample(out, tag string, rs *rules.Ruleset, words []string, cases []gen
 	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) {

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

@@ -0,0 +1,113 @@
+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,
+        );
+      }
+    });
+  }
+});