haiku.rag.config exported two configuration instances: the lazy _config
behind get_config/set_config, and Config, loaded at import time. Nothing
linked them, and eleven signatures captured Config as a default argument,
so set_config could not reach the factories, the client, the store or the
MCP server. reranking/base.py went further and snapshotted the configured
reranker name into a class attribute at import.
Config is removed. Internal defaults are config: AppConfig | None = None,
resolved through get_config() per call. RerankerBase._model is None and
CohereReranker takes its model name as an argument, like every other
reranker.
The suite patched attributes on Config while production read the instance
get_config() returns, a different object, so those patches were no-ops
waiting to happen. They now go through get_config().
Cover the remaining paths in the client, context, downloads, title
generation, document tools and store models, and add fail_under=100 so
uncovered lines fail CI.
Six lines that no test can reach get a pragma with its reason: the docling
import guard, the nameless PDF attachment, the FS symlink OSError guard that
resolve(strict=False) absorbs, the docling bbox and LanceDB document-id
shape guards, the tag-retention branch vacuum makes unreachable, and Monty's
Rust-thread print callback.
Fix test_find_config_file_user_config, which wrote its config into the cwd it
had chdir'd to, so the cwd branch answered first and the user-directory
lookup it names was never exercised.
