diff --git a/packages/mnswpr/adapters/replay-progress.js b/packages/mnswpr/adapters/replay-progress.js
new file mode 100644
index 0000000..b203320
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+++ b/packages/mnswpr/adapters/replay-progress.js
@@ -0,0 +1,57 @@
+// @ts-check
+import { MinesweeperRules } from '../core/minesweeper/rules.js'
+
+/**
+ * @typedef {import('../core/minesweeper/rules.js').MoveEvent} MnswprMoveEvent
+ * @typedef {import('../core/minesweeper/board.js').Layout} Layout
+ */
+
+/**
+ * The percent-cleared progress reducer for Minesweeper — mnswpr's first concrete
+ * implementation of the replay engine's `ProgressReducer<MnswprMoveEvent>` seam
+ * (see `@cozy-games/replay` / replay-02). Given the ordered slice of move-events
+ * played so far, it returns completion as
+ * `revealed safe cells / total safe cells * 100`.
+ *
+ * Why it needs the board: a single `reveal` or `chord` event floods MANY cells,
+ * but the recorded move-event only carries `{ type, r, c }` — not how many cells
+ * opened. So the reducer takes the board as closure input (consistent with the
+ * interface design) and replays the moves through the pure core rules. That makes
+ * reveals flood, chords reveal via their (non-flagged) neighbors, and
+ * flags/unflags only gate chords — never advancing progress themselves — with no
+ * cell double-counted. The engine stays game-blind; all interpretation is here.
+ *
+ * @param {Layout} layout - the recorded board (as produced by `generateBoard`)
+ * @returns {(events: { event: MnswprMoveEvent }[]) => number} a reducer to `[0, 100]`
+ */
+export function createProgressReducer(layout) {
+  const totalSafe = layout.rows * layout.cols - layout.mines
+  return function progress(events) {
+    // A board with no safe cells is vacuously fully cleared (and avoids /0).
+    if (totalSafe === 0) return 100
+    let state = MinesweeperRules.fromLayout(layout)
+    for (const record of events) {
+      const move = toMove(record.event)
+      if (move) state = MinesweeperRules.apply(state, move).state
+    }
+    return (state.revealedSafe / totalSafe) * 100
+  }
+}
+
+/**
+ * Map a recorded move-event back to the rules move that produced it: `flag` and
+ * `unflag` are both the toggle move `flag`; `reveal` and `chord` pass through.
+ * Unknown kinds are ignored.
+ *
+ * @param {MnswprMoveEvent} e
+ * @returns {{ type: 'reveal' | 'flag' | 'chord', r: number, c: number } | null}
+ */
+function toMove(e) {
+  switch (e && e.type) {
+    case 'reveal': return { type: 'reveal', r: e.r, c: e.c }
+    case 'chord': return { type: 'chord', r: e.r, c: e.c }
+    case 'flag':
+    case 'unflag': return { type: 'flag', r: e.r, c: e.c }
+    default: return null
+  }
+}
diff --git a/packages/mnswpr/test/replay-progress.test.js b/packages/mnswpr/test/replay-progress.test.js
new file mode 100644
index 0000000..9347ffb
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+++ b/packages/mnswpr/test/replay-progress.test.js
@@ -0,0 +1,123 @@
+import { describe, it, expect } from 'vitest'
+import { GameSession, MinesweeperRules, generateBoard, levels } from '../core/index.js'
+import { createProgressReducer } from '../adapters/replay-progress.js'
+
+// Drive a session over an injected layout, capturing the real core-06 move-event
+// stream (onMove). Returns the emitted events and the session.
+function record(layout, moves) {
+  const session = new GameSession(MinesweeperRules, { state: MinesweeperRules.fromLayout(layout) })
+  const events = []
+  session.onMove(e => events.push(e))
+  for (const m of moves) session.applyMove(m)
+  return { events: events.map(event => ({ seq: event.seq, t: event.t, event })), session }
+}
+
+// 3x3, single mine at (0,0); adjacency computed. Total safe = 8.
+const smallBoard = () => ({
+  rows: 3,
+  cols: 3,
+  mines: 1,
+  cells: [
+    [{ mine: true, adjacent: 0 }, { mine: false, adjacent: 1 }, { mine: false, adjacent: 0 }],
+    [{ mine: false, adjacent: 1 }, { mine: false, adjacent: 1 }, { mine: false, adjacent: 0 }],
+    [{ mine: false, adjacent: 0 }, { mine: false, adjacent: 0 }, { mine: false, adjacent: 0 }]
+  ],
+  mineLocations: [[0, 0]]
+})
+
+describe('mnswpr progress reducer (percent-cleared)', () => {
+  it('progresses a scripted full game from 0% to 100%, monotonically', () => {
+    // A real generated board; reveal every safe cell in row-major order to win.
+    const layout = generateBoard(9, 9, 10, { seed: 7, safeCell: { r: 0, c: 0 } })
+    const progress = createProgressReducer(layout)
+
+    const session = new GameSession(MinesweeperRules, { state: MinesweeperRules.fromLayout(layout) })
+    const events = []
+    session.onMove(e => events.push({ seq: e.seq, t: e.t, event: e }))
+    for (let r = 0; r < 9; r++) {
+      for (let c = 0; c < 9; c++) {
+        if (!session.state.grid.at(r, c).mine) session.applyMove({ type: 'reveal', r, c })
+      }
+    }
+    expect(session.status()).toBe('won')
+
+    expect(progress([])).toBe(0)                       // nothing revealed yet
+    expect(progress(events)).toBe(100)                 // full clear
+    expect(progress(events.slice(0, 1))).toBeGreaterThan(0) // first reveal opens a region
+
+    // monotonic non-decreasing across every prefix
+    let prev = -1
+    for (let k = 0; k <= events.length; k++) {
+      const p = progress(events.slice(0, k))
+      expect(p).toBeGreaterThanOrEqual(prev)
+      prev = p
+    }
+  })
+
+  it('counts flooded reveals by cells opened, not by event count', () => {
+    const layout = smallBoard()
+    const progress = createProgressReducer(layout)
+    // Revealing the far corner (2,2) floods every one of the 8 safe cells.
+    const { events } = record(layout, [{ type: 'reveal', r: 2, c: 2 }])
+    expect(events).toHaveLength(1)      // one event...
+    expect(progress(events)).toBe(100)  // ...but all 8 safe cells cleared
+  })
+
+  it('flag and unflag events leave progress unchanged', () => {
+    const layout = smallBoard()
+    const progress = createProgressReducer(layout)
+    // reveal one numbered cell (1/8), then flag + unflag the mine.
+    const { events } = record(layout, [
+      { type: 'reveal', r: 0, c: 1 }, // reveals just itself (adjacent 1)
+      { type: 'flag', r: 0, c: 0 },   // flag the mine
+      { type: 'flag', r: 0, c: 0 }    // unflag it
+    ])
+    expect(events.map(e => e.event.type)).toEqual(['reveal', 'flag', 'unflag'])
+
+    const afterReveal = progress(events.slice(0, 1))
+    expect(afterReveal).toBeCloseTo(12.5, 5) // 1 / 8
+    expect(progress(events.slice(0, 2))).toBe(afterReveal) // + flag: unchanged
+    expect(progress(events)).toBe(afterReveal)             // + unflag: unchanged
+  })
+
+  it('counts the cells a chord reveals', () => {
+    const layout = smallBoard()
+    const progress = createProgressReducer(layout)
+    // reveal (0,1)=1, flag the mine (0,0), then chord (0,1): its 1 flag matches
+    // its value, so it reveals the rest of the board.
+    const { events } = record(layout, [
+      { type: 'reveal', r: 0, c: 1 },
+      { type: 'flag', r: 0, c: 0 },
+      { type: 'chord', r: 0, c: 1 }
+    ])
+    expect(events.map(e => e.event.type)).toEqual(['reveal', 'flag', 'chord'])
+
+    expect(progress(events.slice(0, 1))).toBeCloseTo(12.5, 5) // 1/8 after reveal
+    expect(progress(events.slice(0, 2))).toBeCloseTo(12.5, 5) // flag doesn't advance
+    expect(progress(events)).toBe(100)                        // chord clears the rest
+  })
+
+  it('reflects a partial game (lost run stops where it stopped)', () => {
+    // Reveal a couple of cells then step on the mine — progress reflects only the
+    // safe cells cleared before the loss.
+    const layout = smallBoard()
+    const progress = createProgressReducer(layout)
+    const { events, session } = record(layout, [
+      { type: 'reveal', r: 0, c: 1 },
+      { type: 'reveal', r: 1, c: 0 },
+      { type: 'reveal', r: 0, c: 0 } // mine → lost
+    ])
+    expect(session.status()).toBe('lost')
+    expect(progress(events)).toBeCloseTo(25, 5) // 2 of 8 safe cells cleared
+  })
+
+  it('is usable as the replay engine progress adapter (shape check)', () => {
+    // The reducer matches ProgressReducer<T>: (events) => number in [0,100].
+    const { rows, cols, mines } = levels.beginner
+    const progress = createProgressReducer(generateBoard(rows, cols, mines, { seed: 1 }))
+    const v = progress([])
+    expect(typeof v).toBe('number')
+    expect(v).toBeGreaterThanOrEqual(0)
+    expect(v).toBeLessThanOrEqual(100)
+  })
+})