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Chimera

Focus Chain

chimera.context.focus provides token-budget-aware context selection. Instead of sending everything to the LLM, FocusChain ranks context items by relevance and selects the most important ones that fit within a configurable token budget.

Key Classes

Section titled “Key Classes”
ClassDescription
ContextItemA piece of context with content, source, tokens, and relevance fields
FocusChainSelects the highest-relevance items that fit within a token budget

Quick Start

Section titled “Quick Start”
from chimera.context.focus import FocusChain


chain = FocusChain(token_budget=4000)


chain.add("def hello(): ...", source="file:utils.py", relevance=0.9)
chain.add("README content...", source="file:README.md", relevance=0.3)
chain.add("Test fixtures...", source="file:conftest.py", relevance=0.7)


# Select items that fit the budget, highest relevance first
selected = chain.select()
for item in selected:
    print(f"{item.source} (relevance={item.relevance}, tokens={item.tokens})")

Adding Files from an Environment

Section titled “Adding Files from an Environment”
from chimera.context.focus import FocusChain
from chimera.env.local import LocalEnvironment


env = LocalEnvironment(workdir="/my/project")
chain = FocusChain(token_budget=8000)


chain.add_file("src/main.py", env, relevance=1.0)
chain.add_files(["tests/test_main.py", "pyproject.toml"], env, relevance=0.5)

Rendering as a Prompt Section

Section titled “Rendering as a Prompt Section”

to_prompt_section() renders the selected items as a Markdown block ready to inject into a system prompt:

utils.py
section = chain.to_prompt_section()
# Returns:
# ## Context
# def hello(): ...

API Summary

Section titled “API Summary”
MethodDescription
add(content, source, relevance)Add a text item with estimated token count
add_file(path, env, relevance)Add a file’s content from an environment
add_files(paths, env, relevance)Add multiple files
select()Return items fitting the budget, sorted by relevance
to_prompt_section()Render selected items as Markdown
clear()Remove all items
Section titled “Related”