Successfully implemented punctuation preservation for Aristocrat ciphers while maintaining punctuation stripping for Patristocrat ciphers.

• Line 148-158: Updated aristocrat encoding to preserve all punctuation and spacing
• Line 174: Fixed TypeScript type annotation for encodedLetterCounts

Key Logic:

• Aristocrat: Encode only letters (/[A-Z]/), preserve everything else (spaces, punctuation)
• Patristocrat: Strip all non-letters, group into 5-letter blocks (no change from before)

Updated to handle letter-only indexing while displaying punctuation:

• visualIndexFor(): Maps group/char position to visual position in encoded string
• letterIndexFromVisual(): Converts visual position to letter-only array index
• isLetterAtVisual(): Checks if character at position is a letter

• handleLetterChange(): Works with letter-only indices, finds matching encoded letters
• handleKeyDown(): Backspace handling with letter-only indices
• handleClear(): Clears only letter positions
• isDuplicated(): Checks duplicates using letter-only indices
• attemptedOriginalFor(): Maps encoded letters to attempted decryption
• attemptedEncodedFor(): Maps attempted letters to encoded letters

• decryptionAttempt now only tracks letters: cipher.encoded.replace(/[^A-Z]/g, '')
• Input refs array sized for letters only

• Display layer: Shows all characters including punctuation
• Input layer: Only creates input boxes for letters, displays punctuation as text

Comprehensive test suite with 8 tests:

1. Aristocrat - preserves punctuation and spacing: Verifies commas, periods, exclamation marks, etc. are preserved
2. Aristocrat - letters are properly substituted: Validates correct substitution with apostrophes
3. Patristocrat - strips punctuation and groups into 5-letter blocks: Ensures no punctuation in output
4. Patristocrat - same substitution but different formatting: Confirms both use same cipher
5. Caesar cipher - aristocrat preserves punctuation: Tests Caesar as K1 with empty keyword
6. Letter counts - only counts letters: Verifies punctuation doesn't affect frequency analysis
7. cleanOriginal - only contains letters: Ensures answer checking works correctly
8. Various punctuation marks: Tests hyphens, ellipses, parentheses, etc.

All tests pass! ✅

• cipher.encoded: Full string with letters, spaces, and punctuation (aristocrat) or letters + spaces only (patristocrat)
• decryptionAttempt[]: Array of only letters (no punctuation or spaces)
• Mapping: Helper functions convert between visual positions and letter-only array indices

Input: "Hello, World!"

Aristocrat Mode:

• cipher.encoded: "KHOOR, ZRUOG!" (letters encoded, punctuation preserved)
• decryptionAttempt: ["", "", "", "", "", "", "", "", "", ""] (10 letters only)
• User sees: K H O O R , W R U O G ! with inputs only under letters

Patristocrat Mode:

• cipher.encoded: "KHOOR ZRUOG" (punctuation stripped, grouped)
• decryptionAttempt: ["", "", "", "", "", "", "", "", "", ""] (same 10 letters)
• User sees: KHOOR ZRUOG with inputs under all characters

1. More authentic: Real cryptograms preserve punctuation
2. Better hints: Punctuation provides clues about sentence structure
3. Cleaner code: Separation between display (with punctuation) and state (letters only)
4. Backward compatible: Patristocrat unchanged, existing games work
5. Well tested: Comprehensive test coverage ensures correctness

Run tests:

deno test substitutionCipher.test.ts

All 8 tests pass with type checking enabled.