BRAIN.md: declarative model routing for your repo

# BRAIN.md — model routing rules for this repo
# Spec: https://prysm1.com/brain-md

# Hard cost ceiling — no single request can exceed this
max_cost_per_request: 0.05

# Default routing mode when no rule matches
default_mode: balanced

rules:
  # Coding and code review → code-optimized model
  - when: "code"
    model: "claude-sonnet-4.5"

  # Math proofs and formal reasoning → best reasoning model
  - when: "reasoning"
    model: "deepseek-r1"

  # Real-time questions (news, weather, stock prices) → search-grounded
  - when: "realtime"
    model: "sonar"

  # Translations → budget multilingual
  - when: "translate"
    routing_mode: agility

  # Summaries → cheapest model that can read long context
  - when: "summarize"
    routing_mode: agility

# These models are never selected, even if the router would otherwise pick them
blocked:
  - gpt-5.2-pro    # Too expensive for this project

from prysm import Prysm

# BRAIN.md is auto-discovered from the current directory or its ancestors.
client = Prysm()

# This call is classified as "reasoning" → routes to deepseek-r1
resp = client.complete("Prove that every even integer > 2 is the sum of two primes")
print(resp.choices[0].message.content)

# This call is classified as "code" → routes to claude-sonnet-4.5
code = client.complete("Refactor this class to use dataclasses", model="auto")

result = client.validate_brain(open("BRAIN.md").read())
print(result["valid"])     # True
print(result["warnings"])  # ['model "claude-sonnet-4.5" is premium — consider "claude-haiku-4.5" for cost']

prysm brain validate BRAIN.md
# ✓ BRAIN.md is valid
# 2 warnings: ...

url = client.brain_share(open("BRAIN.md").read(), title="My cost-safe dev config")["short_url"]
print(url)   # https://prysm1.com/b/abc123def456

<!-- Embed in your README -->
[![BRAIN.md](https://api.prysm1.com/v1/brain/badge?model=deepseek-r1)](https://prysm1.com/b/abc123def456)

curl https://api.prysm1.com/v1/b/abc123def456
# {"config": {"max_cost_per_request": 0.05, "rules": [...], "blocked": [...]}}

# .github/workflows/ai-cost-gate.yml
- name: Validate AI routing config
  run: |
    pip install prysm1
    python -c "
    from prysm import Prysm
    c = Prysm()
    r = c.validate_brain(open('BRAIN.md').read())
    if not r['valid']:
        print('BRAIN.md is invalid:', r['errors'])
        exit(1)
    print('BRAIN.md OK')
    "