D1172 — OpenCode's global MCP entry lives in its config directory

Decision. The global OpenCode MCP entry, Cartographer's own (connect) and a KB's mcp artifact, is written under the mcp key of ~/.config/opencode/opencode.json. An entry an earlier version wrote to $HOME/opencode.json is removed from there: a KB artifact through the generic relocation (D360), Cartographer's own entry by connect/sync once the new one is written, and by disconnect from either file. The project cell stays opencode.json at the repository root.

Why. Both majors load global config only from their XDG config directory (1.x Global.Path.config, 2.x ConfigDiscovery.discover, checked on the source of v1.19.4 and v2.1.4; the config docs name ~/.config/opencode/opencode.json). $HOME/opencode.json is reached only as a project file by walking up from the session folder: 1.x stops at the git root, so a session in a repository never saw the entry; 2.x walks to /, so a session outside $HOME never saw it, and the entry ranked as project config. The cost is that Cartographer now merges into the user's own global OpenCode config: a .json file there that holds comments is refused (not valid JSON), as for every JSON client.

Alternatives rejected. Keeping $HOME/opencode.json and documenting it: the entry is missing from most sessions, which is the bug. Writing both files: wherever the walk-up still finds the old file, its copy overrides the global one as project config. Leaving the old entry for the user to delete: it shadows the global one in sessions that still find it, with the URL of the day it was written. Honouring XDG_CONFIG_HOME: no other OpenCode cell does (D360), and changing all of them is its own decision.

Consequences. The next connect or sync moves the entry and says so in a warning; only the names Cartographer manages leave the old file, which is deleted once nothing but the $schema hint is left. mcpProviderFromPath keeps mapping opencode.json to OpenCode so an old lock entry is pruned.