diff --git a/assets/scripts/modules/save/CocosStorage.ts b/assets/scripts/modules/save/CocosStorage.ts
new file mode 100644
index 0000000..c527472
--- /dev/null
+++ b/assets/scripts/modules/save/CocosStorage.ts
@@ -0,0 +1,64 @@
+import { sys } from 'cc';
+import { IStorage, MemoryStorage } from './IStorage';
+
+/**
+ * The one file in the save module that touches the engine.
+ *
+ * `sys.localStorage` is backed by the browser store on web and by a native file
+ * on Android and iOS, so one implementation covers every target. It can still
+ * fail — private browsing, a full quota, a locked profile — so every call is
+ * guarded and falls back to an in-memory store, which keeps the session
+ * consistent even when nothing can be persisted.
+ */
+export class CocosStorage implements IStorage {
+    private readonly _fallback = new MemoryStorage();
+    private _usingFallback = false;
+
+    /** True once a storage call has failed and the session went in-memory. */
+    get degraded(): boolean {
+        return this._usingFallback;
+    }
+
+    getItem(key: string): string | null {
+        if (this._usingFallback) {
+            return this._fallback.getItem(key);
+        }
+        try {
+            return sys.localStorage.getItem(key);
+        } catch (error) {
+            this._degrade(error);
+            return this._fallback.getItem(key);
+        }
+    }
+
+    setItem(key: string, value: string): void {
+        if (!this._usingFallback) {
+            try {
+                sys.localStorage.setItem(key, value);
+                return;
+            } catch (error) {
+                this._degrade(error);
+            }
+        }
+        this._fallback.setItem(key, value);
+    }
+
+    removeItem(key: string): void {
+        if (!this._usingFallback) {
+            try {
+                sys.localStorage.removeItem(key);
+                return;
+            } catch (error) {
+                this._degrade(error);
+            }
+        }
+        this._fallback.removeItem(key);
+    }
+
+    private _degrade(error: unknown): void {
+        if (this._usingFallback) return;
+        this._usingFallback = true;
+        const message = error instanceof Error ? error.message : String(error);
+        console.warn(`[save] device storage is unavailable, progress will not persist: ${message}`);
+    }
+}
diff --git a/assets/scripts/modules/save/CocosStorage.ts.meta b/assets/scripts/modules/save/CocosStorage.ts.meta
new file mode 100644
index 0000000..ea1639d
--- /dev/null
+++ b/assets/scripts/modules/save/CocosStorage.ts.meta
@@ -0,0 +1,9 @@
+{
+  "ver": "4.0.24",
+  "importer": "typescript",
+  "imported": true,
+  "uuid": "c355de0c-e0e7-4e52-8805-6a4fdacd5bef",
+  "files": [],
+  "subMetas": {},
+  "userData": {}
+}
diff --git a/assets/scripts/modules/save/ISaveSection.ts b/assets/scripts/modules/save/ISaveSection.ts
new file mode 100644
index 0000000..f34f1a1
--- /dev/null
+++ b/assets/scripts/modules/save/ISaveSection.ts
@@ -0,0 +1,25 @@
+/**
+ * One independently saved slice of player progress.
+ *
+ * ARCHITECTURE.md asks for a save built from several classes, each handling its
+ * own part, keyed by the class. The key here is an explicit string rather than
+ * `constructor.name` on purpose: release builds minify class names, and a
+ * renamed class would silently orphan every existing save.
+ */
+export interface ISaveSection {
+    /** Stable identifier. Never change it once a build has shipped. */
+    readonly key: string;
+
+    /** Current contents as a JSON-safe value. */
+    save(): unknown;
+
+    /**
+     * Restores from a previously saved value. Must tolerate anything — an older
+     * shape, a newer shape, or outright rubbish — by falling back to defaults
+     * rather than throwing.
+     */
+    load(data: unknown): void;
+
+    /** Returns to the state of a player who has never played. */
+    reset(): void;
+}
diff --git a/assets/scripts/modules/save/ISaveSection.ts.meta b/assets/scripts/modules/save/ISaveSection.ts.meta
new file mode 100644
index 0000000..0fd0646
--- /dev/null
+++ b/assets/scripts/modules/save/ISaveSection.ts.meta
@@ -0,0 +1,9 @@
+{
+  "ver": "4.0.24",
+  "importer": "typescript",
+  "imported": true,
+  "uuid": "48cc13db-e29f-4fa9-955f-fab6c05f76b4",
+  "files": [],
+  "subMetas": {},
+  "userData": {}
+}
diff --git a/assets/scripts/modules/save/IStorage.ts b/assets/scripts/modules/save/IStorage.ts
new file mode 100644
index 0000000..a346d53
--- /dev/null
+++ b/assets/scripts/modules/save/IStorage.ts
@@ -0,0 +1,35 @@
+/**
+ * The key-value store a save is written to.
+ *
+ * Kept behind an interface so the save logic itself has no engine dependency
+ * and can be tested headlessly. `CocosStorage` is the real implementation;
+ * `MemoryStorage` is the one tests use.
+ */
+export interface IStorage {
+    getItem(key: string): string | null;
+    setItem(key: string, value: string): void;
+    removeItem(key: string): void;
+}
+
+/** An in-process store. Used by tests, and as a fallback when storage is unavailable. */
+export class MemoryStorage implements IStorage {
+    private readonly _data = new Map<string, string>();
+
+    getItem(key: string): string | null {
+        const value = this._data.get(key);
+        return value === undefined ? null : value;
+    }
+
+    setItem(key: string, value: string): void {
+        this._data.set(key, value);
+    }
+
+    removeItem(key: string): void {
+        this._data.delete(key);
+    }
+
+    /** Test helper: everything currently stored. */
+    get entries(): ReadonlyMap<string, string> {
+        return this._data;
+    }
+}
diff --git a/assets/scripts/modules/save/IStorage.ts.meta b/assets/scripts/modules/save/IStorage.ts.meta
new file mode 100644
index 0000000..f5b7a22
--- /dev/null
+++ b/assets/scripts/modules/save/IStorage.ts.meta
@@ -0,0 +1,9 @@
+{
+  "ver": "4.0.24",
+  "importer": "typescript",
+  "imported": true,
+  "uuid": "a51ebd26-39af-478f-ac08-a839af126032",
+  "files": [],
+  "subMetas": {},
+  "userData": {}
+}
diff --git a/assets/scripts/modules/save/SaveManager.ts b/assets/scripts/modules/save/SaveManager.ts
new file mode 100644
index 0000000..e4966c2
--- /dev/null
+++ b/assets/scripts/modules/save/SaveManager.ts
@@ -0,0 +1,149 @@
+import { ISaveSection } from './ISaveSection';
+import { IStorage } from './IStorage';
+
+/** Bumped only when the envelope around the sections changes, not the sections themselves. */
+export const SAVE_FORMAT_VERSION = 1;
+
+const DEFAULT_SLOT = 'fool.save';
+
+interface SaveEnvelope {
+    version: number;
+    sections: Record<string, unknown>;
+}
+
+export interface SaveManagerOptions {
+    /** Storage key the whole save lives under. */
+    slot?: string;
+    /** Where warnings go. Defaults to the console; tests pass their own. */
+    warn?: (message: string) => void;
+}
+
+/**
+ * Collects the registered sections into one JSON document and puts it back
+ * again on load, exactly as ARCHITECTURE.md describes.
+ *
+ * Loading is deliberately forgiving. A save that cannot be parsed, or a single
+ * section whose payload has gone bad, resets only what it has to and lets
+ * everything else through — a bad release should not be able to brick a player's
+ * progress, and a partial load beats no load at all.
+ */
+export class SaveManager {
+    private readonly _storage: IStorage;
+    private readonly _slot: string;
+    private readonly _warn: (message: string) => void;
+    private readonly _sections: ISaveSection[] = [];
+
+    constructor(storage: IStorage, options: SaveManagerOptions = {}) {
+        this._storage = storage;
+        this._slot = options.slot ?? DEFAULT_SLOT;
+        this._warn = options.warn ?? ((m) => console.warn(`[save] ${m}`));
+    }
+
+    /** Registers a section. Keys must be unique. */
+    register(section: ISaveSection): void {
+        if (this._sections.some((s) => s.key === section.key)) {
+            throw new Error(`A save section with key '${section.key}' is already registered`);
+        }
+        this._sections.push(section);
+    }
+
+    get sections(): readonly ISaveSection[] {
+        return this._sections;
+    }
+
+    /** Serialises every section and writes the result. */
+    save(): void {
+        const envelope: SaveEnvelope = { version: SAVE_FORMAT_VERSION, sections: {} };
+        for (const section of this._sections) {
+            try {
+                envelope.sections[section.key] = section.save();
+            } catch (error) {
+                this._warn(`section '${section.key}' failed to save: ${describe(error)}`);
+            }
+        }
+
+        try {
+            this._storage.setItem(this._slot, JSON.stringify(envelope));
+        } catch (error) {
+            // A full or disabled store must not take the game down with it.
+            this._warn(`could not write the save: ${describe(error)}`);
+        }
+    }
+
+    /**
+     * Reads the save and hands each section its own payload. Sections with no
+     * stored data — a new section in a new build, or a brand new player — are
+     * reset to their defaults.
+     */
+    load(): void {
+        const envelope = this._read();
+
+        for (const section of this._sections) {
+            const data = envelope?.sections[section.key];
+            if (data === undefined) {
+                section.reset();
+                continue;
+            }
+            try {
+                section.load(data);
+            } catch (error) {
+                this._warn(`section '${section.key}' failed to load, resetting it: ${describe(error)}`);
+                section.reset();
+            }
+        }
+    }
+
+    /** Resets every section and removes the stored save. */
+    reset(): void {
+        for (const section of this._sections) {
+            section.reset();
+        }
+        try {
+            this._storage.removeItem(this._slot);
+        } catch (error) {
+            this._warn(`could not clear the save: ${describe(error)}`);
+        }
+    }
+
+    private _read(): SaveEnvelope | null {
+        let raw: string | null;
+        try {
+            raw = this._storage.getItem(this._slot);
+        } catch (error) {
+            this._warn(`could not read the save: ${describe(error)}`);
+            return null;
+        }
+        if (raw === null || raw === '') {
+            return null;
+        }
+
+        let parsed: unknown;
+        try {
+            parsed = JSON.parse(raw);
+        } catch (error) {
+            this._warn(`the save is not valid JSON, starting fresh: ${describe(error)}`);
+            return null;
+        }
+
+        if (!isRecord(parsed) || !isRecord(parsed.sections)) {
+            this._warn('the save has an unrecognisable shape, starting fresh');
+            return null;
+        }
+
+        const version = typeof parsed.version === 'number' ? parsed.version : 0;
+        if (version > SAVE_FORMAT_VERSION) {
+            // Written by a newer build. Read what we can rather than wiping it.
+            this._warn(`the save is from a newer version (${version}), reading it cautiously`);
+        }
+
+        return { version, sections: parsed.sections };
+    }
+}
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+    return typeof value === 'object' && value !== null && !Array.isArray(value);
+}
+
+function describe(error: unknown): string {
+    return error instanceof Error ? error.message : String(error);
+}
diff --git a/assets/scripts/modules/save/SaveManager.ts.meta b/assets/scripts/modules/save/SaveManager.ts.meta
new file mode 100644
index 0000000..e840717
--- /dev/null
+++ b/assets/scripts/modules/save/SaveManager.ts.meta
@@ -0,0 +1,9 @@
+{
+  "ver": "4.0.24",
+  "importer": "typescript",
+  "imported": true,
+  "uuid": "273eda8d-570a-4dee-8070-c03134c4568f",
+  "files": [],
+  "subMetas": {},
+  "userData": {}
+}
diff --git a/assets/scripts/modules/save/StatsSection.ts b/assets/scripts/modules/save/StatsSection.ts
new file mode 100644
index 0000000..041f380
--- /dev/null
+++ b/assets/scripts/modules/save/StatsSection.ts
@@ -0,0 +1,84 @@
+import { ISaveSection } from './ISaveSection';
+
+export type MatchOutcome = 'win' | 'loss' | 'draw';
+
+interface StatsData {
+    played: number;
+    won: number;
+    lost: number;
+    drawn: number;
+    streak: number;
+    bestStreak: number;
+}
+
+function emptyStats(): StatsData {
+    return { played: 0, won: 0, lost: 0, drawn: 0, streak: 0, bestStreak: 0 };
+}
+
+/**
+ * How the player has been doing. The only section iteration 1 ships; currency
+ * and level progress will join it later without touching `SaveManager`.
+ */
+export class StatsSection implements ISaveSection {
+    static readonly KEY = 'stats';
+
+    readonly key = StatsSection.KEY;
+
+    private _data: StatsData = emptyStats();
+
+    get played(): number { return this._data.played; }
+    get won(): number { return this._data.won; }
+    get lost(): number { return this._data.lost; }
+    get drawn(): number { return this._data.drawn; }
+    /** Wins in a row right now. A loss resets it; a draw leaves it alone. */
+    get streak(): number { return this._data.streak; }
+    get bestStreak(): number { return this._data.bestStreak; }
+
+    recordResult(outcome: MatchOutcome): void {
+        this._data.played += 1;
+        switch (outcome) {
+            case 'win':
+                this._data.won += 1;
+                this._data.streak += 1;
+                this._data.bestStreak = Math.max(this._data.bestStreak, this._data.streak);
+                break;
+            case 'loss':
+                this._data.lost += 1;
+                this._data.streak = 0;
+                break;
+            case 'draw':
+                this._data.drawn += 1;
+                break;
+        }
+    }
+
+    save(): unknown {
+        return { ...this._data };
+    }
+
+    load(data: unknown): void {
+        const source = (typeof data === 'object' && data !== null ? data : {}) as Record<string, unknown>;
+        const defaults = emptyStats();
+        this._data = {
+            played: count(source.played, defaults.played),
+            won: count(source.won, defaults.won),
+            lost: count(source.lost, defaults.lost),
+            drawn: count(source.drawn, defaults.drawn),
+            streak: count(source.streak, defaults.streak),
+            bestStreak: count(source.bestStreak, defaults.bestStreak),
+        };
+        // A save edited by hand should not be able to show a nonsense best.
+        this._data.bestStreak = Math.max(this._data.bestStreak, this._data.streak);
+    }
+
+    reset(): void {
+        this._data = emptyStats();
+    }
+}
+
+/** Reads a non-negative whole number, or falls back. */
+function count(value: unknown, fallback: number): number {
+    return typeof value === 'number' && Number.isFinite(value) && value >= 0
+        ? Math.floor(value)
+        : fallback;
+}
diff --git a/assets/scripts/modules/save/StatsSection.ts.meta b/assets/scripts/modules/save/StatsSection.ts.meta
new file mode 100644
index 0000000..c03b819
--- /dev/null
+++ b/assets/scripts/modules/save/StatsSection.ts.meta
@@ -0,0 +1,9 @@
+{
+  "ver": "4.0.24",
+  "importer": "typescript",
+  "imported": true,
+  "uuid": "c9c5a957-f40b-4887-a88b-5697c3b37c0c",
+  "files": [],
+  "subMetas": {},
+  "userData": {}
+}
diff --git a/docs/PLAN.md b/docs/PLAN.md
index da102cf..a5f65d8 100644
--- a/docs/PLAN.md
+++ b/docs/PLAN.md
@@ -50,12 +50,12 @@ progress. The Cocos layer only renders state and turns taps into actions.
 - [x] `MatchRunner` driving a full headless match
 - [x] Soak test: thousands of seeded self-play matches finish with no illegal state
 
-### M3 — Savegame module `[ ]`
-- [ ] `ISaveSection` contract, `SaveManager` registry, JSON keyed by section name
-- [ ] Storage backend over `sys.localStorage` (works on web and native)
-- [ ] `StatsSection`: games played / won / lost, current and best win streak
-- [ ] Versioning + tolerant load (unknown or missing sections do not break a load)
-- [ ] Tests for save/load round-trip and corrupted-payload recovery
+### M3 — Savegame module `[x]`
+- [x] `ISaveSection` contract, `SaveManager` registry, JSON keyed by section name
+- [x] Storage backend over `sys.localStorage` (works on web and native)
+- [x] `StatsSection`: games played / won / lost, current and best win streak
+- [x] Versioning + tolerant load (unknown or missing sections do not break a load)
+- [x] Tests for save/load round-trip and corrupted-payload recovery
 
 ### M4 — Art pipeline `[ ]`
 - [ ] Pick the 36 needed faces from `local/`, downscale to the 1080-wide budget
diff --git a/docs/TECHNICAL.md b/docs/TECHNICAL.md
index 080bd81..d6ddb0a 100644
--- a/docs/TECHNICAL.md
+++ b/docs/TECHNICAL.md
@@ -24,9 +24,11 @@ from the layers below it and never from the ones above.
   core/      pure rules and bots — no `cc` import anywhere
 ```
 
-The rule enforced by review and by the test harness: **nothing under
-`assets/scripts/core/` may import from `cc`.** It is plain TypeScript, runnable
-under Node, and that is what makes the rules testable without the engine.
+The rule, enforced by `npm run check:core-purity`: **nothing under
+`assets/scripts/core/` may import from `cc`**, and under
+`assets/scripts/modules/` only the adapters explicitly listed in that script
+may. Everything else is plain TypeScript, runnable under Node, which is what
+makes the rules and the save format testable without the engine.
 
 ## Folder map
 
@@ -49,7 +51,8 @@ assets/
       match/                  Match (stateful shell), runMatch (headless driver)
       util/                   seeded RNG, shuffle
     modules/
-      save/                   SaveManager, ISaveSection, StatsSection, storage
+      save/                   SaveManager, ISaveSection, StatsSection,
+                              IStorage + MemoryStorage, CocosStorage (engine)
     app/                      Bootstrap, ServiceLocator, SceneRouter
     ui/
       lobby/                  lobby screen controller
@@ -108,6 +111,12 @@ warning rather than failing the whole load, so a bad release cannot brick a save
 
 Keys are explicit string constants, not class names — release builds minify.
 
+The document written is `{ version, sections: { <key>: <payload> } }`. Storage
+sits behind `IStorage`, so all of the save logic is testable headlessly;
+`CocosStorage` is the only file in the module that imports the engine, and it
+falls back to an in-memory store when the device refuses to persist (private
+browsing, a full quota) rather than taking the game down.
+
 ## Conventions
 
 - TypeScript, 4-space indent, `PascalCase` for types, `camelCase` for members,
diff --git a/scripts/check-core-purity.mjs b/scripts/check-core-purity.mjs
index 95de5a9..61a993c 100644
--- a/scripts/check-core-purity.mjs
+++ b/scripts/check-core-purity.mjs
@@ -1,28 +1,59 @@
-// Guards the one architectural rule that the type system cannot express:
-// assets/scripts/core must never import the Cocos engine. See docs/TECHNICAL.md.
+// Guards the one architectural rule the type system cannot express: the game
+// logic must not depend on the engine. See docs/TECHNICAL.md.
+//
+//   core/     never imports `cc`, at all.
+//   modules/  is engine-aware, but only through the adapters listed below —
+//             everything else in it stays testable headlessly.
+//
+// A new file that needs `cc` under modules/ is a deliberate decision, so it has
+// to be added here on purpose rather than slipping in unnoticed.
 import { readdirSync, readFileSync, statSync } from 'node:fs';
-import { join } from 'node:path';
+import { join, relative, sep } from 'node:path';
+
+const PURE_ROOT = 'assets/scripts/core';
+const MODULES_ROOT = 'assets/scripts/modules';
+const ENGINE_ADAPTERS = new Set([
+    'save/CocosStorage.ts',
+]);
+
+const ENGINE_IMPORT = /\bfrom\s+['"](cc|cc\/env)['"]/;
 
-const ROOT = 'assets/scripts/core';
-const FORBIDDEN = /from\s+['"](cc|cc\/env|db:\/\/)/;
 const offenders = [];
 
-function walk(dir) {
+function walk(dir, onFile) {
     for (const entry of readdirSync(dir)) {
-        const p = join(dir, entry);
-        if (statSync(p).isDirectory()) walk(p);
-        else if (p.endsWith('.ts')) {
-            const src = readFileSync(p, 'utf8');
-            src.split('\n').forEach((line, i) => {
-                if (FORBIDDEN.test(line)) offenders.push(`${p}:${i + 1}  ${line.trim()}`);
-            });
-        }
+        const path = join(dir, entry);
+        if (statSync(path).isDirectory()) walk(path, onFile);
+        else if (path.endsWith('.ts')) onFile(path);
     }
 }
 
-walk(ROOT);
-if (offenders.length) {
-    console.error('core/ must not import the engine:\n' + offenders.join('\n'));
+function engineImports(path) {
+    return readFileSync(path, 'utf8')
+        .split('\n')
+        .map((line, i) => ({ line: line.trim(), number: i + 1 }))
+        .filter((entry) => ENGINE_IMPORT.test(entry.line));
+}
+
+walk(PURE_ROOT, (path) => {
+    for (const hit of engineImports(path)) {
+        offenders.push(`${path}:${hit.number}  ${hit.line}   (core/ must never import the engine)`);
+    }
+});
+
+walk(MODULES_ROOT, (path) => {
+    const key = relative(MODULES_ROOT, path).split(sep).join('/');
+    if (ENGINE_ADAPTERS.has(key)) return;
+    for (const hit of engineImports(path)) {
+        offenders.push(
+            `${path}:${hit.number}  ${hit.line}   (add '${key}' to ENGINE_ADAPTERS if this is intended)`,
+        );
+    }
+});
+
+if (offenders.length > 0) {
+    console.error(`Engine dependency in code that must stay pure:\n${offenders.join('\n')}`);
     process.exit(1);
 }
+
 console.log('core purity OK');
diff --git a/tests/modules/save/SaveManager.spec.ts b/tests/modules/save/SaveManager.spec.ts
new file mode 100644
index 0000000..b0028cd
--- /dev/null
+++ b/tests/modules/save/SaveManager.spec.ts
@@ -0,0 +1,277 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+import { ISaveSection } from '@modules/save/ISaveSection';
+import { IStorage, MemoryStorage } from '@modules/save/IStorage';
+import { SAVE_FORMAT_VERSION, SaveManager } from '@modules/save/SaveManager';
+import { StatsSection } from '@modules/save/StatsSection';
+
+const SLOT = 'test.save';
+
+/** A minimal section, so manager behaviour can be tested without StatsSection. */
+class CounterSection implements ISaveSection {
+    readonly key: string;
+    value = 0;
+
+    constructor(key = 'counter') {
+        this.key = key;
+    }
+
+    save(): unknown {
+        return { value: this.value };
+    }
+
+    load(data: unknown): void {
+        const record = data as { value?: unknown };
+        if (typeof record?.value !== 'number') {
+            throw new Error('not a counter');
+        }
+        this.value = record.value;
+    }
+
+    reset(): void {
+        this.value = 0;
+    }
+}
+
+function makeManager(storage: IStorage = new MemoryStorage()) {
+    const warnings: string[] = [];
+    const manager = new SaveManager(storage, { slot: SLOT, warn: (m) => warnings.push(m) });
+    return { manager, storage, warnings };
+}
+
+describe('SaveManager', () => {
+    it('writes one document keyed by section', () => {
+        const { manager, storage } = makeManager();
+        const counter = new CounterSection();
+        manager.register(counter);
+        counter.value = 7;
+
+        manager.save();
+
+        const raw = JSON.parse(storage.getItem(SLOT) as string);
+        expect(raw).toEqual({ version: SAVE_FORMAT_VERSION, sections: { counter: { value: 7 } } });
+    });
+
+    it('round-trips through a fresh manager', () => {
+        const storage = new MemoryStorage();
+        const first = makeManager(storage);
+        const a = new CounterSection();
+        first.manager.register(a);
+        a.value = 42;
+        first.manager.save();
+
+        const second = makeManager(storage);
+        const b = new CounterSection();
+        second.manager.register(b);
+        second.manager.load();
+
+        expect(b.value).toBe(42);
+    });
+
+    it('resets a section that has never been saved', () => {
+        const { manager } = makeManager();
+        const counter = new CounterSection();
+        counter.value = 99;
+        manager.register(counter);
+
+        manager.load();
+
+        expect(counter.value).toBe(0);
+    });
+
+    it('rejects two sections with the same key', () => {
+        const { manager } = makeManager();
+        manager.register(new CounterSection('dup'));
+        expect(() => manager.register(new CounterSection('dup'))).toThrow(/already registered/);
+    });
+
+    it('clears storage and every section on reset', () => {
+        const { manager, storage } = makeManager();
+        const counter = new CounterSection();
+        manager.register(counter);
+        counter.value = 5;
+        manager.save();
+
+        manager.reset();
+
+        expect(counter.value).toBe(0);
+        expect(storage.getItem(SLOT)).toBeNull();
+    });
+});
+
+describe('SaveManager recovering from bad data', () => {
+    it('starts fresh when the save is not JSON', () => {
+        const storage = new MemoryStorage();
+        storage.setItem(SLOT, 'not json at all');
+        const { manager, warnings } = makeManager(storage);
+        const counter = new CounterSection();
+        counter.value = 3;
+        manager.register(counter);
+
+        manager.load();
+
+        expect(counter.value).toBe(0);
+        expect(warnings.join(' ')).toMatch(/not valid JSON/);
+    });
+
+    it('starts fresh when the save has the wrong shape', () => {
+        const storage = new MemoryStorage();
+        storage.setItem(SLOT, JSON.stringify([1, 2, 3]));
+        const { manager, warnings } = makeManager(storage);
+        manager.register(new CounterSection());
+
+        manager.load();
+
+        expect(warnings.join(' ')).toMatch(/unrecognisable/);
+    });
+
+    it('resets only the section whose payload is broken', () => {
+        const storage = new MemoryStorage();
+        storage.setItem(SLOT, JSON.stringify({
+            version: SAVE_FORMAT_VERSION,
+            sections: { good: { value: 11 }, bad: 'rubbish' },
+        }));
+        const { manager, warnings } = makeManager(storage);
+        const good = new CounterSection('good');
+        const bad = new CounterSection('bad');
+        bad.value = 8;
+        manager.register(good);
+        manager.register(bad);
+
+        manager.load();
+
+        expect(good.value).toBe(11);
+        expect(bad.value).toBe(0);
+        expect(warnings.join(' ')).toMatch(/'bad' failed to load/);
+    });
+
+    it('reads what it can from a save written by a newer build', () => {
+        const storage = new MemoryStorage();
+        storage.setItem(SLOT, JSON.stringify({
+            version: SAVE_FORMAT_VERSION + 5,
+            sections: { counter: { value: 4 }, unknownFutureThing: { x: 1 } },
+        }));
+        const { manager, warnings } = makeManager(storage);
+        const counter = new CounterSection();
+        manager.register(counter);
+
+        manager.load();
+
+        expect(counter.value).toBe(4);
+        expect(warnings.join(' ')).toMatch(/newer version/);
+    });
+
+    it('survives a storage device that throws', () => {
+        const broken: IStorage = {
+            getItem: () => { throw new Error('quota'); },
+            setItem: () => { throw new Error('quota'); },
+            removeItem: () => { throw new Error('quota'); },
+        };
+        const { manager, warnings } = makeManager(broken);
+        manager.register(new CounterSection());
+
+        expect(() => { manager.load(); manager.save(); manager.reset(); }).not.toThrow();
+        expect(warnings.length).toBeGreaterThan(0);
+    });
+
+    it('survives a section that throws while saving', () => {
+        const { manager, storage, warnings } = makeManager();
+        manager.register({
+            key: 'explodes',
+            save() { throw new Error('boom'); },
+            load() { /* never reached */ },
+            reset() { /* nothing */ },
+        });
+        const counter = new CounterSection();
+        manager.register(counter);
+        counter.value = 2;
+
+        manager.save();
+
+        const raw = JSON.parse(storage.getItem(SLOT) as string);
+        expect(raw.sections.counter).toEqual({ value: 2 });
+        expect(warnings.join(' ')).toMatch(/'explodes' failed to save/);
+    });
+
+    it('warns through the console when no handler is supplied', () => {
+        const spy = vi.spyOn(console, 'warn').mockImplementation(() => undefined);
+        const storage = new MemoryStorage();
+        storage.setItem('fool.save', '{');
+        new SaveManager(storage).load();
+        expect(spy).toHaveBeenCalled();
+        spy.mockRestore();
+    });
+});
+
+describe('StatsSection', () => {
+    let stats: StatsSection;
+
+    beforeEach(() => {
+        stats = new StatsSection();
+    });
+
+    it('starts empty', () => {
+        expect(stats.played).toBe(0);
+        expect(stats.won).toBe(0);
+        expect(stats.bestStreak).toBe(0);
+    });
+
+    it('counts each outcome', () => {
+        stats.recordResult('win');
+        stats.recordResult('loss');
+        stats.recordResult('draw');
+
+        expect(stats.played).toBe(3);
+        expect(stats.won).toBe(1);
+        expect(stats.lost).toBe(1);
+        expect(stats.drawn).toBe(1);
+    });
+
+    it('tracks the current streak and the best one', () => {
+        stats.recordResult('win');
+        stats.recordResult('win');
+        stats.recordResult('win');
+        expect(stats.streak).toBe(3);
+        expect(stats.bestStreak).toBe(3);
+
+        stats.recordResult('loss');
+        expect(stats.streak).toBe(0);
+        expect(stats.bestStreak).toBe(3);
+
+        stats.recordResult('win');
+        expect(stats.streak).toBe(1);
+        expect(stats.bestStreak).toBe(3);
+    });
+
+    it('does not let a draw break a streak', () => {
+        stats.recordResult('win');
+        stats.recordResult('draw');
+        expect(stats.streak).toBe(1);
+    });
+
+    it('round-trips through a save', () => {
+        stats.recordResult('win');
+        stats.recordResult('win');
+        stats.recordResult('loss');
+
+        const restored = new StatsSection();
+        restored.load(JSON.parse(JSON.stringify(stats.save())));
+
+        expect(restored.save()).toEqual(stats.save());
+    });
+
+    it('repairs a hand-edited save instead of trusting it', () => {
+        stats.load({ played: 'lots', won: -4, lost: 2.7, streak: 9, bestStreak: 1 });
+
+        expect(stats.played).toBe(0);
+        expect(stats.won).toBe(0);
+        expect(stats.lost).toBe(2);
+        expect(stats.streak).toBe(9);
+        expect(stats.bestStreak).toBe(9);
+    });
+
+    it('falls back to defaults for a payload of the wrong type', () => {
+        stats.recordResult('win');
+        stats.load(null);
+        expect(stats.played).toBe(0);
+    });
+});
diff --git a/tsconfig.test.json b/tsconfig.test.json
index 7049d09..f24895e 100644
--- a/tsconfig.test.json
+++ b/tsconfig.test.json
@@ -10,8 +10,14 @@
         "types": ["vitest/globals"],
         "baseUrl": ".",
         "paths": {
-            "@core/*": ["assets/scripts/core/*"]
+            "@core/*": ["assets/scripts/core/*"],
+            "@modules/*": ["assets/scripts/modules/*"]
         }
     },
-    "include": ["assets/scripts/core/**/*.ts", "tests/**/*.ts"]
+    "include": [
+        "assets/scripts/core/**/*.ts",
+        "assets/scripts/modules/**/*.ts",
+        "tests/**/*.ts"
+    ],
+    "exclude": ["assets/scripts/modules/save/CocosStorage.ts"]
 }
diff --git a/vitest.config.mts b/vitest.config.mts
index 829263e..e2f3a79 100644
--- a/vitest.config.mts
+++ b/vitest.config.mts
@@ -5,6 +5,7 @@ export default defineConfig({
     resolve: {
         alias: {
             '@core': resolve(__dirname, 'assets/scripts/core'),
+            '@modules': resolve(__dirname, 'assets/scripts/modules'),
         },
     },
     test: {
diff --git a/vitest.stats.mts b/vitest.stats.mts
index 9951334..e395162 100644
--- a/vitest.stats.mts
+++ b/vitest.stats.mts
@@ -7,6 +7,7 @@ export default defineConfig({
     resolve: {
         alias: {
             '@core': resolve(__dirname, 'assets/scripts/core'),
+            '@modules': resolve(__dirname, 'assets/scripts/modules'),
         },
     },
     test: {