diff --git a/scripts/extract-grids.js b/scripts/extract-grids.js
new file mode 100644
index 0000000..418f0b5
--- /dev/null
+++ b/scripts/extract-grids.js
@@ -0,0 +1,176 @@
+#!/usr/bin/env node
+// Extract unique grid patterns from NYT crosswords JSON and xd puzzle files
+// Output: one file per size (grids_15x15.txt, grids_21x21.txt)
+// Format: each grid is lines of '#' (black) and '.' (white), separated by blank lines
+
+const fs = require('fs')
+const path = require('path')
+
+const grids = new Map() // size -> Set of pattern strings
+
+function addGrid(width, height, pattern) {
+  // only keep 15x15 and 21x21
+  if (!((width === 15 && height === 15) || (width === 21 && height === 21))) return
+  const key = `${width}x${height}`
+  if (!grids.has(key)) grids.set(key, new Set())
+  grids.get(key).add(pattern)
+}
+
+function gridToPattern(grid, width, height) {
+  const lines = []
+  for (let r = 0; r < height; r++) {
+    let line = ''
+    for (let c = 0; c < width; c++) {
+      const cell = grid[r * width + c]
+      line += (cell === '.' || cell === '#') ? '#' : '.'
+    }
+    lines.push(line)
+  }
+  return lines.join('\n')
+}
+
+// validate pattern: every white cell in runs >= 3 both directions, connected
+function isValidPattern(pattern, width, height) {
+  const cells = pattern.split('\n').map(l => l.split(''))
+
+  // check runs >= 3 in both directions for every white cell
+  for (let r = 0; r < height; r++) {
+    for (let c = 0; c < width; c++) {
+      if (cells[r][c] !== '.') continue
+      // across run length
+      let as_ = c, ae = c
+      while (as_ > 0 && cells[r][as_-1] === '.') as_--
+      while (ae < width-1 && cells[r][ae+1] === '.') ae++
+      if (ae - as_ + 1 < 3) return false
+      // down run length
+      let ds = r, de = r
+      while (ds > 0 && cells[ds-1][c] === '.') ds--
+      while (de < height-1 && cells[de+1][c] === '.') de++
+      if (de - ds + 1 < 3) return false
+    }
+  }
+
+  // connectivity check (BFS)
+  let startR = -1, startC = -1, whiteCount = 0
+  for (let r = 0; r < height && startR < 0; r++)
+    for (let c = 0; c < width && startR < 0; c++)
+      if (cells[r][c] === '.') { startR = r; startC = c }
+  if (startR < 0) return false
+
+  for (let r = 0; r < height; r++)
+    for (let c = 0; c < width; c++)
+      if (cells[r][c] === '.') whiteCount++
+
+  const visited = Array.from({length: height}, () => Array(width).fill(false))
+  const queue = [[startR, startC]]
+  visited[startR][startC] = true
+  let reached = 1
+  while (queue.length > 0) {
+    const [r, c] = queue.shift()
+    for (const [dr, dc] of [[-1,0],[1,0],[0,-1],[0,1]]) {
+      const nr = r+dr, nc = c+dc
+      if (nr >= 0 && nr < height && nc >= 0 && nc < width && !visited[nr][nc] && cells[nr][nc] === '.') {
+        visited[nr][nc] = true
+        reached++
+        queue.push([nr, nc])
+      }
+    }
+  }
+  return reached === whiteCount
+}
+
+// --- Process NYT JSON files ---
+function processNYT(dir) {
+  if (!fs.existsSync(dir)) { console.log('NYT dir not found:', dir); return }
+  let count = 0
+  const walk = (d) => {
+    for (const entry of fs.readdirSync(d, { withFileTypes: true })) {
+      const full = path.join(d, entry.name)
+      if (entry.isDirectory()) { walk(full); continue }
+      if (!entry.name.endsWith('.json')) continue
+      try {
+        const data = JSON.parse(fs.readFileSync(full, 'utf8'))
+        const w = data.size?.cols || 0
+        const h = data.size?.rows || 0
+        if ((w === 15 && h === 15) || (w === 21 && h === 21)) {
+          if (data.grid && data.grid.length === w * h) {
+            const pattern = gridToPattern(data.grid, w, h)
+            if (isValidPattern(pattern, w, h)) {
+              addGrid(w, h, pattern)
+              count++
+            }
+          }
+        }
+      } catch {}
+    }
+  }
+  walk(dir)
+  console.log(`NYT: extracted ${count} valid grids`)
+}
+
+// --- Process xd files ---
+function processXD(dir) {
+  if (!fs.existsSync(dir)) { console.log('XD dir not found:', dir); return }
+  let count = 0
+  const walk = (d) => {
+    for (const entry of fs.readdirSync(d, { withFileTypes: true })) {
+      const full = path.join(d, entry.name)
+      if (entry.isDirectory()) { walk(full); continue }
+      if (!entry.name.endsWith('.xd')) continue
+      try {
+        const text = fs.readFileSync(full, 'utf8')
+        // xd format: headers, blank line, grid section, blank line, clues
+        // grid lines are like: .ABC.DEF. where . = black, letters = white
+        const sections = text.split(/\n\n+/)
+        let gridSection = null
+        for (const sec of sections) {
+          const lines = sec.trim().split('\n').filter(l => l.trim())
+          // grid section: all lines same length, contain only letters, dots, #, and spaces
+          if (lines.length >= 5 && lines.every(l => /^[A-Za-z.#_]+$/.test(l.trim())) &&
+              new Set(lines.map(l => l.trim().length)).size === 1) {
+            gridSection = lines.map(l => l.trim())
+            break
+          }
+        }
+        if (!gridSection) continue
+        const h = gridSection.length
+        const w = gridSection[0].length
+        if (!((w === 15 && h === 15) || (w === 21 && h === 21))) continue
+
+        const patternLines = gridSection.map(line =>
+          line.split('').map(c => (c === '.' || c === '#' || c === '_') ? '#' : '.').join('')
+        )
+        const pattern = patternLines.join('\n')
+        if (isValidPattern(pattern, w, h)) {
+          addGrid(w, h, pattern)
+          count++
+        }
+      } catch {}
+    }
+  }
+  walk(dir)
+  console.log(`XD: extracted ${count} valid grids`)
+}
+
+// --- Main ---
+const nytDir = process.argv[2] || '/tmp/nyt_crosswords'
+const xdDir = process.argv[3] || '/tmp/xd-puzzles'
+const outDir = process.argv[4] || 'data/grid-templates'
+
+console.log('Processing NYT crosswords...')
+processNYT(nytDir)
+
+console.log('Processing xd puzzles...')
+processXD(xdDir)
+
+// Write output
+fs.mkdirSync(outDir, { recursive: true })
+
+for (const [size, patterns] of grids) {
+  const outFile = path.join(outDir, `grids_${size}.txt`)
+  const content = [...patterns].join('\n\n') + '\n'
+  fs.writeFileSync(outFile, content)
+  console.log(`${size}: ${patterns.size} unique patterns -> ${outFile}`)
+}
+
+console.log('Done!')