v0.4.1

Added

• Number-theory predicates in math — is_even, is_odd, is_negative, is_positive,
  is_integer, is_square, is_perfect, is_prime, is_coprime. They live in the
  expression namespace so they compose, and they return booleans that coerce to 1 and 0, so
  is_prime(11) + is_prime(12) + is_prime(13) is 2 — which is the only batching math has,
  and is now documented rather than left to be rediscovered. A predicate applied to a free
  symbol names the symbol instead of answering None. (#57, #63)
• Bounded ranges in numbers.sequence — kind=primes start=50 end=80 gives
  53, 59, 61, 67, 71, 73, 79. Same for squares and fibonacci. end is what asks for a
  range, so a start on its own is still ignored and still says so. (#57)
• The physical constants in math — gravitational_constant … fine_structure_constant,
  each under a long name everywhere and its conventional short name (G, c, h, R) only
  in the modes whose answer is a number. c and G are the most common single-letter
  variables in algebra, so solve(["a + b = c"]) still treats c as an unknown, and a vars
  entry always wins. Values come from pint's CODATA registry, and every use is named in
  assumptions with its value and unit. (#55)
• holidays modes festival, upcoming and compare. check and next are date-first;
  these are name-first and window-first — "when is Durga Puja", "what is coming up in October",
  "which dates does West Bengal observe that Assam does not". A multi-day festival comes back
  as one thing with its days named, not as unrelated rows sharing a prefix, and common names
  resolve to whatever the dataset calls the same festival (Durga Puja is filed as Dussehra)
  with the substitution stated. A name it does not carry is refused with the near misses,
  because "not in this dataset" and "no such festival" are different claims. (#87, #88, #94)
• holidays.list can return iCalendar or CSV — format="ics" puts the calendar in a
  calendar, which is the thing people actually do with one. (#93)
• Holiday names in other languages — language="hi", "bn", "ta" and eight more for
  India, discoverable through mode categories. (#76)
• A festival can anchor date arithmetic — {"festival": "Saptami", "year": 2026, "region": "IN", "subdiv": "WB"} works wherever datetime takes a date, so "three days before Saptami"
  is one call rather than a lookup, some arithmetic and hoping both were right. (#92)
• Somewhere to report a wrong answer. POST /feedback for agents holding a key and a form
  at /report for signed-in people, both filing an issue on the tracker nobody outside can
  see. Off unless LEFTBRAIN_FEEDBACK_TOKEN and LEFTBRAIN_FEEDBACK_REPO are set. Anything
  key-shaped is blanked before filing, and the reporter is recorded — a key prefix or a GitHub
  login — never their email. (#53)
• Every published parameter now says what it is for, and mode lists what each tool can
  do. 0.4.0 gave them types; this gives them meanings, from the same text the documentation
  site already carries. (#64)

Fixed

• 17 % 5 returned 0.85. % was read as a percentage wherever it appeared, so it became
  (17/100) 5 — wrong by a factor of 20, with % read as /100 as the only tell. Both are
  legitimate readings of %, so it now asks which was meant and takes
  percent="modulus"|"percent" as the answer, the way angle already works. mod is the
  spelling with one meaning and never asks. This also uncovered a precedence bug in mod
  itself: 2^10 mod 7 matched 10 as its left operand and answered 2^(10 mod 7) = 8
  instead of 1024 mod 7 = 2. (#97)
• A SIP with no opening balance was refused. "growth and SIPs" is advertised at tool level,
  but principal was required — so "5,000 a month for ten years", which is what a SIP
  normally is, came back as 'principal' is required. The arithmetic was right all along.
  (#98)
• A year the holiday source does not reach answered with an empty list. India's tables run
  1948–2100; asking for 2200 returned nothing, which reads exactly like "no holidays that
  year". It is refused now, naming the window. Every date also carries its provenance — source,
  calendar, covered years, language and categories. (#90)
• holidays.check could not say that a date was a festival. is_holiday and is_weekend
  had to carry every question. It now answers with is_observed, day_off and
  observances[], each classified in one vocabulary that means the same thing in every
  country. is_holiday keeps its old meaning. (#89, #95)
• A rejected math function named only what failed. primepi now comes back with the near
  misses and the accepted set, factorint returns real factors instead of a stringified dict,
  and the description no longer claims "ANY arithmetic" against a partial allowlist. (#63)

Changed

• toolref moved out of leftbrain.web to leftbrain.toolref. It only ever needed
  contract and core, and leftbrain.web.__init__ imports starlette — a server extra an
  MCP-only install does not have. This is internal; nothing about the published tools changed.