Struct Config 

pub struct Config {
    pub schema_path: Option<PathBuf>,
    pub db_path: Option<PathBuf>,
    pub user_dir: Option<PathBuf>,
    pub project_dir: Option<PathBuf>,
    pub backup_retention: Option<usize>,
    pub snapshot_retention: Option<usize>,
}

Runtime configuration for the mini-app-mcp server.

Constructed exclusively via Config::load; there is no public constructor so callers always go through the validated loading path.

Fields

• schema_path / db_path: legacy single-table paths (set when MINI_APP_SCHEMA and MINI_APP_DB are present).
• user_dir: base directory for User-scope tables (~/.mini-app/ by default, overridden by MINI_APP_USER_DIR).
• project_dir: override directory for Project-scope tables (./.mini-app/ by default, overridden by MINI_APP_PROJECT_DIR).

Fields

schema_path: Option<PathBuf>

Path to the schema.yaml file that defines the table’s field schema.

Set via the MINI_APP_SCHEMA environment variable. None when only directory-based multi-table configuration is used.

db_path: Option<PathBuf>

Path to the SQLite database file.

Set via the MINI_APP_DB environment variable. None when only directory-based multi-table configuration is used.

user_dir: Option<PathBuf>

Base directory for User-scope table definitions.

Defaults to ~/.mini-app/ when MINI_APP_USER_DIR is not set. Each subdirectory <table>/ is expected to contain schema.yaml and <table>.db.

project_dir: Option<PathBuf>

Override directory for Project-scope table definitions.

Defaults to ./.mini-app/ (current working directory) when MINI_APP_PROJECT_DIR is not set. Same subdirectory layout as user_dir; Project entries override User entries with the same table name (file-level swap, not field-level merge).

backup_retention: Option<usize>

Number of backup pairs ({table}.{ts}.yaml + {table}.{ts}.db) to retain in _backup/ before the oldest are purged.

Defaults to 10 when MINI_APP_BACKUP_RETENTION is not set. Set via the MINI_APP_BACKUP_RETENTION environment variable (must be a positive integer; non-parsable values are silently ignored and the default of 10 is used).

snapshot_retention: Option<usize>

Number of snapshot files ({table}.{ts}.db) to retain in _snapshots/ before the oldest are purged.

Defaults to 10 when MINI_APP_SNAPSHOT_RETENTION is not set. Set via the MINI_APP_SNAPSHOT_RETENTION environment variable (must be a positive integer; non-parsable values are silently ignored and the default of 10 is used).

This field is intentionally separate from backup_retention to enforce the snapshot retention isolation Crux constraint: snapshot and backup lifecycles are managed independently.

Implementations

impl Config

pub fn load() -> Result<Self, MiniAppError>

Load configuration from the environment.

Attempts to read .mini-app-mcp.env from the current directory first (via dotenvy). Variables already set in the process environment take precedence over values from the file (dotenvy’s default behaviour).

Environment variables

Variable	Required	Description
MINI_APP_SCHEMA	Legacy mode only	Path to schema.yaml
MINI_APP_DB	Legacy mode only	Path to the SQLite database file
MINI_APP_USER_DIR	Optional	User-scope table directory (default ~/.mini-app/)
MINI_APP_PROJECT_DIR	Optional	Project-scope table directory (default ./.mini-app/)
MINI_APP_BACKUP_RETENTION	Optional	Number of backup pairs to keep (default 10)
MINI_APP_SNAPSHOT_RETENTION	Optional	Number of snapshot files to keep (default 10)

At least one of the legacy pair (MINI_APP_SCHEMA + MINI_APP_DB) or a directory env must resolve to a usable table configuration. When neither legacy env vars nor a discoverable directory exist the server can still start (directory scan skips missing dirs with a warning).

Returns

A Config on success. The presence of legacy fields vs directory fields determines which mode the server operates in.

Errors

Returns MiniAppError::Config only if an env var is present but cannot be read (which is unusual — the standard env API only fails on invalid UTF-8). Does not panic.

pub fn has_legacy_env(&self) -> bool

Returns true when both legacy single-table env vars (MINI_APP_SCHEMA and MINI_APP_DB) are present in this config.

Returns

true if and only if both schema_path and db_path are Some.

pub fn backup_retention(&self) -> usize

Returns the number of backup pairs to keep per table.

Uses the value of backup_retention when set, otherwise defaults to 10. This default is documented in MINI_APP_BACKUP_RETENTION.

Returns

The retention limit as a usize. Always at least 1 (a value of 0 would delete all backups on every write).

pub fn snapshot_retention(&self) -> usize

Returns the number of snapshot files to keep per table.

Uses the value of snapshot_retention when set, otherwise defaults to 10. This default is documented in MINI_APP_SNAPSHOT_RETENTION.

This getter is intentionally separate from backup_retention to enforce snapshot retention isolation: snapshot and backup lifecycles are managed via independent environment variables and independent retention counters (Crux: snapshot retention isolation).

Returns

The retention limit as a usize. Always at least 1 (a value of 0 would delete all snapshots on every write).

Trait Implementations

impl Clone for Config

fn clone(&self) -> Config

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Config

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.