fix(config): the resources folder is the one next to the application file - never the working directory (a direct python app.py included)

[acn-ericlaw]

What

• AppConfig resolves resources/application.yml (.yaml, .properties) next to the application file: mercury-serve passes the app's folder (load_config(path, app_dir=...)), and the lazy singleton anchors on the script Python ran (main_script_dir(), from __main__.__file__), so a direct python app.py finds its folder too. The working directory is never searched. --config <file> still names another file; the companion app-log-context.yaml follows the same folder (AppConfig.resources_dir); AppConfig.source is the absolute path of the file found; the startup log reports Configuration: <path>.
• Tests: the convention test rewritten and six added, two of them subprocess runs from a decoy working directory (python app.py, python -m mercury_composable.cli app.py, and --config). 208 tests, ruff and basedpyright clean. Verified by hand: python examples/llm-helper/llm_helper.py from the repository root now logs Configuration: .../examples/llm-helper/resources/application.yml and starts as llm-helper.
• Docs: README, the configuration reference, the config guide, the examples' application.yml comments and READMEs (the direct-run line), and the CHANGELOG with the upgrade note.

Why

During the Bedrock drive a direct python llm_helper.py from the repository root started with no configuration at all (the default name and port, no health dependency): the CLI's working-directory-first lookup never ran on that path, and the lazy loader probed the working directory. The rule applied here is the maintainer's: the script knows where it sits, so the resources folder is resolved relative to the application file, never by scanning the working directory - the engines' classpath convention, where the configuration travels with the application. A stray resources/ in the launch directory can no longer shadow the application's own. Upgrade note: an application that kept resources/ in the working directory with its application file elsewhere passes --config, or moves the folder next to the file.

The Node twin is the mercury-nodejs PR of the same title (#113, Accenture/mercury-nodejs#113).

Co-Authored-By: Claude Fable 5.1 noreply@anthropic.com

🤖 Generated with Claude Code