Decision: abx config delete removes one stored value

Status: implemented Implemented: 2026-09-30

Problem

The only way to drop a stored setting was abx config set KEY "". That works, but it is easy to miss: config had get, set, list, and init, and no command whose name says the value is being removed. template delete already exists for the remote template.

Decision

• abx config delete KEY removes the value stored by abx config set. The key falls back to its built-in default or becomes not set.
• shortcuts.<name> removes that one alias. Reserved command names stay reserved.
• abx config set KEY "" keeps doing the same removal.
• An environment variable that still overrides the key is not unset. The result names the variable and does not print its value.
• There is still no abx config reset and no command that deletes ~/.abx.

Test strategy

tests/test_cli/test_config_commands.py: deleting a credential leaves the other .env lines, deleting region falls back to cn-hangzhou, an unknown key exits 2, an overriding environment variable is named but not printed, and shortcuts.ps is removed.

Files changed

• src/agent_sandbox/cli/commands/config_cmd.py
• docs/{en,zh}/reference/cli-reference.md, docs/{en,zh}/design/cli-design.md
• CHANGELOG.md