[BUG] Empty ~/basic-memory directory recreated on every config load (mkdir side effect in config validator)

[MHoroszowski]

Summary

On every config load, Basic Memory recreates an empty ~/basic-memory directory even when the user has configured a completely different project path (e.g. ~/Documents/BasicMemory) and no BASIC_MEMORY_HOME is set. The directory reappears after nearly every bm command and each MCP server startup.

The recreated directory is always empty and unused — real notes/DB live at the correctly-configured path — so this is a cosmetic-but-persistent surprise rather than data loss.

Reproduction

Config (~/.basic-memory/config.json) points main at a custom path:

"projects": { "main": { "path": "/Users/me/Documents/BasicMemory", "mode": "local" } },
"default_project": "main"

Then:

rm -rf ~/basic-memory
bm reindex          # or: bm project list  (anything that loads config)
ls -d ~/basic-memory   # -> exists again, empty
bm --version        # does NOT recreate it (never loads config)

bm project list still correctly reports only main -> ~/Documents/BasicMemory; the ~/basic-memory dir is a phantom.

Root cause

The culprit is a filesystem side effect in a Pydantic validator, triggered by a throwaway config instance. In src/basic_memory/config.py (line numbers from current main):

1. ConfigManager.load_config() builds a throwaway config only to read env-var defaults, passing no file data (~line 612):

   env_config = BasicMemoryConfig()
   env_dict = env_config.model_dump()

2. With no file data and BASIC_MEMORY_HOME unset, model_post_init injects a default project pointing at ~/basic-memory (~lines 505-509):

   if not self.projects:
       self.projects["main"] = ProjectEntry(
           path=str(Path(os.getenv("BASIC_MEMORY_HOME", Path.home() / "basic-memory"))))

3. The @model_validator(mode="after") ensure_project_paths_exists then mkdirs that path as a side effect (~line 545):

   path.mkdir(parents=True)

So merely instantiating BasicMemoryConfig() to inspect env defaults writes a directory to disk — against a default path the user never selected.

Suggested fixes (any one breaks the chain)

• Don't create directories inside a model_validator. Move ensure_project_paths_exists's mkdir into an explicit initialization step (the code path that actually commits/uses a project), so constructing a config has no filesystem effect.
• Or make the env-default probe side-effect-free — read env fields without triggering model_post_init/after-validators (e.g. a dedicated defaults helper), rather than constructing a full BasicMemoryConfig().

Environment

• basic-memory 0.22.1 (latest release; Homebrew install, Python 3.14)
• macOS
• BASIC_MEMORY_HOME unset; single local project at a custom path

Workaround

Setting export BASIC_MEMORY_HOME=<real vault path> stops the recreation, because the throwaway default then points at an already-existing directory and the mkdir becomes a no-op.