Add AI configuration file support (#911)

[emeryberger]

Summary

Addresses #911 - Add configuration file support for Scalene's AI-powered optimization features.

This PR adds support for storing AI provider settings in ~/.scalene/config.json, allowing users to:

• Store API keys and settings persistently without environment variables
• Configure custom endpoints for self-hosted or proxy setups
• Set default providers and models

Changes

New scalene config CLI command

scalene config list                           # list all config values
scalene config set openai_api_key sk-xxx     # set a value
scalene config get openai_api_key            # get a value (shows source)
scalene config clear                          # clear all config
scalene config path                           # show config file path

Configuration Priority

Values are resolved in this order:

1. Environment variables (highest priority)
2. Config file (~/.scalene/config.json)
3. Browser localStorage (lowest priority)

Supported Configuration Keys

Category	Keys
API Keys	openai_api_key, anthropic_api_key, gemini_api_key, azure_api_key, aws_access_key, aws_secret_key
Custom Models	openai_model, anthropic_model, gemini_model, azure_model, aws_model, ollama_model
Custom URLs	openai_url, anthropic_url, azure_api_url, ollama_host, ollama_port
Other	aws_region, azure_api_version, default_provider

Files Changed

• New: scalene/scalene_ai_config.py - Core configuration module
• Modified: scalene/scalene_parseargs.py - Added config subcommand
• Modified: scalene/scalene_utility.py - Use centralized config loading
• Modified: scalene/scalene-gui/* - Extended GUI support for config fields
• Modified: CLAUDE.md - Documentation

Test plan

• scalene config --help shows usage
• scalene config set/get/list/clear/path commands work correctly
• API keys are masked in output
• Config file is created at ~/.scalene/config.json
• Environment variables take precedence over config file
• All existing tests pass
• mypy and ruff pass

🤖 Generated with Claude Code

[emeryberger]

To fix the problem, we need to ensure that sensitive configuration values (API keys, secrets) are never printed in clear text, even partially. The existing logic in _handle_config_command already distinguishes sensitive keys by checking whether "key" or "secret" appears in the key name; we can strengthen that logic so it never exposes any part of the actual value. Instead, for such keys we should always print a constant placeholder such as "***" or "(set)", regardless of the value length.

Concretely, in scalene/scalene_parseargs.py:

• In the "list" subcommand loop (lines 980–986), change the masking for "key"/"secret" keys from value[:8] + "..." if len(value) > 8 else "***" to a fixed placeholder such as "***", so no characters from the secret are shown.
• In the "get" subcommand (lines 1011–1017), similarly change the masking logic for sensitive keys to always show a fixed placeholder, never the first 8 characters of the secret.
• The "set" subcommand already prints "***" for keys containing "key" or "secret", so no change is needed there.

No new functions or imports are needed; we only adjust the string formatting logic in the two relevant branches.

To fix an unused import, remove only the unused symbol from the import statement, keeping the rest of the imports unchanged so existing behavior is preserved.

Concretely, in scalene/scalene_parseargs.py on the from scalene.scalene_ai_config import (...) block (lines 13–22 in your snippet), delete get_all_ai_config from the parenthesized list. Do not touch the other imported names (VALID_CONFIG_KEYS, clear_config, get_config_file, get_config_source, get_config_value, list_config, set_config_value), as they may be used elsewhere in the file. No new methods, imports, or definitions are needed; we are only simplifying the existing import.