Migrate configuration to version 2

Version 2 replaces permissive safety booleans with explicit path policies and makes formatter input/output behavior unambiguous. Version 1 remains readable for compatibility, but ast-mcp never migrates a file automatically.

Preview first

ast-mcp config migrate
ast-mcp config migrate --file ./ast-mcp.toml
ast-mcp config migrate --global

Preview is the default and does not write. Use --check in CI: exit code 0 means current, 2 means migration is required, and 1 means the input is invalid or unsupported.

Write atomically

ast-mcp config migrate --to 2 --write
ast-mcp config migrate --global --write --no-backup

A write uses an adjacent temporary file and atomic replacement, preserves file mode and newline style, and creates <file>.v1.bak unless --no-backup is explicit. Comments and untouched source bytes remain intact. Re-running migration on version 2 is idempotent.

Compatibility mapping

• Existing custom formatters gain a stable id, enabled = true, and mode = "stdout" because v1 consumed stdout.
• Formatting gains fallback = "dprint" where needed to preserve v1 unmatched-file behavior.
• Workspace roots become explicit top-level [[paths]] rules.
• Enabled temporary-directory access becomes an explicit OS-temp rule.
• allow_any_path = true becomes an explicit catch-all rule and emits an UNRESTRICTED warning.
• delete inherits write when omitted; migrated compatibility rules spell out all policies.

Review every generated rule before writing, especially catch-all, temporary, external, or symlink-enabled rules. Prefer request for access that is not universally safe. Persistent user approvals belong only in the user-global version 2 configuration.

Rollout

After migration, restart or reconnect long-lived MCP hosts once so they discover the new server/tool schemas. Subsequent configuration changes hot reload in place. Run config_status to verify the effective generation and formatter order, then use policy_check for representative read, write, delete, and external paths before the first mutation.