chore(mcp-compat): add aggregate command and new save/search options (backend 793f241..99e33da)

[ditto-mcp-maintainer]

Why

Backend MCP/server change in ditto-assistant/backend@99e33da (range 793f241..99e33da) requires this repo to stay compatible.

Triggering backend change

The Ditto MCP server added:

• aggregate_memories — a new read-only tool for counts, breakdowns, and theme discovery.
• Enhanced search_memories with shared filter arguments (since, until, timezone, filter, limit).
• Enhanced save_memory with optional response (assistant side) and vendorId (deduplication id).

What changed here

• New command: heyditto aggregate <group-by> (alias aggregate_memories) with --metrics, --limit, --since, --until, --timezone, --filter, --kg.
• save new options: --response for two-sided memory pairs, --vendor-id for idempotent saves.
• search new options: --limit, --since, --until, --timezone, --filter for structured narrowing.
• Tests: added help-text assertions for the new command and options; all 19 tests pass.

Provenance

Opened by the Ditto MCP-extensions maintenance automation. Run state and prior runs live in the dedicated mcp-extensions-maintainer knowledge graph and the ditto-assistant/ditto-backend-ops-log ledger. A separate reviewer agent will review this PR with fresh context.

Setup / migration notes

None.

[ditto-mcp-maintainer]

Mostly correct and well-scoped. The new aggregate command, save options (--response, --vendor-id), and search filter options all map cleanly to the backend's new MCP surface.

One bug to fix:

--metrics is not actually repeatable despite the help text claiming it is. Commander.js .option("--metrics <metric>", ...) overwrites the value on repeated use; it does not collect into an array. So:

heyditto aggregate source --metrics count --metrics sum

will silently send only ["sum"] to the backend.

Fix: use variadic syntax .option("--metrics <metrics...>", ...) (Commander v12+) or supply a custom parser that accumulates values. The backend's stringSliceArgAny will accept a single string, so one metric still works, but the repeatability claim is misleading and will surprise users.

The rest looks good. Tests cover help text; consider adding a functional test for aggregate argument serialization once the metrics option is fixed.