Heavy duty anagram solver

The heavy-duty anagram solver is here: https://util.in/solver.

Comparison with other tools

The advantages of the util.in solver are:

• Supports "low-confidence" letters, by using lowercase letters instead of uppercase. This allows you to perform search queries that you're pretty sure about, but you'll still get results even if a few letters are wrong.
• Supports much larger queries, e.g. anagrams of dozens of letters or letter groups.

On the other hand, prefer Qat or Nutrimatic for simple queries like "what is an anagram of AAAGMNR" (these tools are much more standard in the puzzle community) or for complex queries (e.g. Qat's equation solver). Note complex ≠ large scale; an anagram of 30 letters is a large query but not complex.

Syntax

Basic

• C.t: a simple query where you know some letters. Periods are wildcards for any letter, uppercase letters mean that you're 100% confident, and lowercase letters mean that you're 80% confident, i.e. the solver may return results with different letters if they're much more common English words.
• CAT.+: the plus sign means the period can be duplicated any number of times (at least 1). The solver will return CATS and CATCH, but not CAST or CAT.
• CATS?: the question mark means the S is optional. The solver will return both CAT and CATS.
• [BC]AT: the square brackets means "B" OR "C", i.e. the solver will return BAT and CAT.
• ([BC]AT)&(C.+): the ampersand means AND. The solver will return CAT, but not BAT.

Anagrams

• <AAAGMNR>: angle brackets are anagrams, i.e. anagram all of the given letters.
• <(AC)T>: parentheses are groups of letters that aren't anagrammed. The solver will return ACT and TAC but not CAT.
• <ACT><INO>: each group of letters is anagrammed, but letters can't be anagrammed between different groups. The solver will return CATION and ACTION, but not ATONIC.

Word boundaries

• "CATION": quotes wrap a single word, so word boundaries are forbidden. The solver will return CATION, but not CAT ION.
• CAT\bION: the "\b" is an enforced word boundary. The solver will return CAT ION, but not CATION.

Advanced

These convenience functions correspond to common puzzle hunt mechanics.

• (CAN~TIO): the interleave operator ~ returns all ways to interleave the two sequences. The solver will return CATION, but not ACTION because the subsequence CAN isn't in the same order.
• \chain(YDU(ST)): this returns all ways to connect the given chain parts into a full chain. A chain starts at some point and moves left or right (wrapping at the ends) until reaching back to the start point. Each chain part (e.g. ST) won't be reordered internally. The solver will return DUSTY and STUDY.

All modifiers can be recursively nested.

Note that the syntax is similar to Nutrimatic, with the exception of uppercase letters (we need to distinguish between confident letters vs. unconfident letters, whereas Nutrimatic does not).