Migrate legacy localStorage entries to new 2048-prefixed keys

[Copilot]

When the 2048- prefix was added to localStorage keys, existing players lost access to their saved high scores, preferences, and unlockables. This adds a one-time migration that copies legacy values into the new keys on startup, without touching unrelated localStorage entries from other games on the same origin. A notification dialog is shown to the player the first (and only) time the migration runs.

Changes

• src/storage/browser.ts

  • Exports legacy key constants (LEGACY_GAME_STATE_KEY, LEGACY_PERSISTENT_STATE_KEY, LEGACY_PREFERENCES_KEY)
  • Exports migrateLocalStorage_v1_3_1() — iterates the legacy→new key map and copies each value only when the legacy key exists and the new key is absent, preventing overwrites of existing new saves; returns true if any migration was performed, false otherwise. The function name is versioned to indicate which app version introduced this migration and to avoid conflicts with any future migrations.

• index.html

  • Adds #migration-dialog-content template with a user-friendly message informing the player their save data was migrated, and a mailto link to contact the developer if anything looks off

• src/index.ts

  • Calls migrateLocalStorage_v1_3_1() immediately after BrowserGameStorage is instantiated; if it returns true, shows the migration notification dialog before game initialization
  • Because migration only runs once (only when old keys exist and new keys don't), the dialog naturally appears only once

• test/browser_storage_test.ts

  • Tests covering: full migration (returns true), no-op when new key already exists (returns false), no-op when no legacy keys present (returns false), partial migration when only some legacy keys exist (returns true)

export const migrateLocalStorage_v1_3_1 = (): boolean => {
    let migrated = false;
    for (const [legacyKey, newKey] of Object.entries(LEGACY_KEY_MAP)) {
        const legacyValue = window.localStorage.getItem(legacyKey);
        if (legacyValue != null && window.localStorage.getItem(newKey) == null) {
            window.localStorage.setItem(newKey, legacyValue);
            migrated = true;
        }
    }
    return migrated;
};

Original prompt

A change was made recently to update the local storage fields to contain a "2048-" prefix, to disambiguate the save data from other games on my website. Players who load this new version will not be able to see their high score, preferences, or unlockables, but they are still available under the old local storage entries. I'd like a function that detects if the player has the old save fields, and selectively brings over these field values to the equivalent field in the new save entry. It's key that we selectively bring these individual values over rather than bring everything over, in case there's something else being used in another game that we do not want.

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[github-actions]

Test Results

 14 files  + 1   45 suites  +7   2m 25s ⏱️ +20s
169 tests +19  169 ✅ +19  0 💤 ±0  0 ❌ ±0 
177 runs  +19  177 ✅ +19  0 💤 ±0  0 ❌ ±0 

Results for commit d6c45ca. ± Comparison against base commit 7bc4d6e.

♻️ This comment has been updated with latest results.

[cloudflare-workers-and-pages]

Deploying 2048-clone with    Cloudflare Pages

Latest commit:	d6c45ca
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Preview URL:	https://55f23532.2048-clone-33h.pages.dev
Branch Preview URL:	https://copilot-migrate-local-storag.2048-clone-33h.pages.dev

View logs

[Coteh]

Can you make the function return whether a migration was performed, and if it was, then pop up a dialog box saying that a migration was done and if there's any issues then contact me at my email. (Take a look at the error dialog template for the email) Make the message user-friendly. Because of the return value, the dialog should only ever appear once, when the migration moves stuff from the old local storage entries to the new one. It should not appear again.

[Copilot]

Done in f652bec. migrateLocalStorage now returns true when at least one entry was migrated, and false otherwise. When true is returned, a migration notification dialog is shown (only on that first load after migration, since subsequent loads won't trigger migration). The dialog uses a new #migration-dialog-content template with a user-friendly message and a mailto link to james.cote.730@gmail.com (same email as the error dialog).

[Copilot]

Just as a heads up, I was blocked by some firewall rules while working on your feedback. Expand below for details.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• o1.ingest.sentry.io
  • Triggering command: /home/REDACTED/work/_temp/ghcca-node/node/bin/node node /home/REDACTED/work/2048-clone/2048-clone/node_modules/.bin/vite build (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

[Coteh]

To make this function more context-aware and to track migrations over time, can we update the migrateLocalStorage function name to include the current version of the application? For example, if the version in package.json is 1.2.3, the function should be named migrateLocalStorage_v1_2_3.

This will help:

• Indicate the version associated with the migration logic.

• Avoid confusion if additional migrations are implemented in future versions.

Let me know what you think!

[Copilot]

Done in ad9d0fe. The function has been renamed to migrateLocalStorage_v1_3_1 (version read from package.json), with all references updated in src/storage/browser.ts, src/index.ts, and test/browser_storage_test.ts.