Add batch memory support and serialize MCP InitializeResult

[savioruz]

Summary

Two commits: (1) Serialize MCP InitializeResult (issue #52 — bug, critical for strict MCP clients like Claude Code), and (2) Add batch memory support across the HTTP API, MCP add_memory tool, and CLI (issue #53). CI green.

Changes

(1) Serialize MCP InitializeResult — commit 92a6aad (issue #52)

• crates/memayu-mcp/src/types.rs: derive/bump serde::Serialize (and keep Deserialize) on the MCP protocol types so the initialize response is emitted correctly:
  • InitializeResult → protocolVersion, serverInfo, capabilities (all #[serde(rename_all = "camelCase")]).
  • ServerInfo { name, version }, ServerCapabilities { instructions?, prompts?, resources?, tools?, auth? }, ToolsCapability { listChanged }, etc. — serialized camelCase per the MCP 2024-11-05 spec.
  • New #[cfg(test)] mod tests (ser_deser + camelCase assertions incl. nested tools.listChanged) — verifies the serialized JSON uses protocol_version→protocolVersion, listChanged (nested), and server_info→serverInfo.
• Fixes MCP initialize response uses snake_case (protocol_version/server_info) instead of camelCase — rejected by strict clients #52: strict MCP clients (Claude Code, etc.) rejected the prior snake_case payload.

(2) Batch memory support — commit 3ee6ec7 (issue #53)

Core:

• crates/memayu-core/src/service.rs: new BatchMemory { content, metadata }, BatchItemResult::Stored/{ id } | Failed/{ error }, and MemoryService::add_memories_batch(user, &[BatchMemory]) -> Result<Vec<BatchItemResult>>. Ingestion loops each item through the existing add_memory (ADD/UPDATE + dedupe) pipeline; per-item failures are collected, only an empty batch raises CoreError::InvalidInput. New CoreError::InvalidInput(String) variant.
• crates/memayu-core/src/lib.rs: re-export BatchMemory/BatchItemResult.

HTTP API:

• crates/memayu-api/src/modules/memory/dto.rs: AddMemoriesBatchRequest { memories: Vec<AddMemoryItem> }, AddMemoryItem { content, metadata }, BatchMemoryError { index, error }, AddMemoriesBatchResponse { status, added, memory_ids, errors }.
• crates/memayu-api/src/transport/handlers/memory.rs: new POST /api/memories/batch → 400 on empty, else add_memories_batch + per-item result mapping into BatchMemoryError { index }. HTTP 200 even with per-item failures (graceful degradation).
• crates/memayu-api/src/transport/routes.rs: register /batch.

MCP:

• crates/memayu-mcp/src/tools/add_memory.rs: add_memory tool gains an optional memories array input (items { content, metadata }); per-item failures are summarized with item {i}: <error> and successes collected. Single-content path unchanged (backward compatible).

CLI:

• bin/memayu/src/cli.rs: new memayu add --batch / memayu batch style invocation accepting multiple memory payloads; per-item error summary to stderr.

Tests

• crates/memayu-api/tests/api.rs: add_memories_batch_stores_all (3 valid → added=3, errors []) and add_memories_batch_reports_per_item_errors (3 with one empty-content → added=2, errors present, HTTP 200).
• bin/memayu/tests/cli.rs: add_batch_stores_all_items, add_batch_reports_partial_failures.
• crates/memayu-mcp/src/types.rs: ser/serde + camelCase test assertions.

Migration / behavior

• No DB schema change.
• Backward compatible API addition: POST /api/memories/add (single) unchanged; /batch is new.
• MCP add_memory schema: memories array is optional → existing single-content calls work unchanged.

Checklist

• MCP initialize response uses snake_case (protocol_version/server_info) instead of camelCase — rejected by strict clients #52 (camelCase MCP InitializeResult) — strict-client compatible.
• Add batch endpoint for memories (HTTP + MCP + CLI) #53 batch endpoint across HTTP API, MCP, CLI.
• per-item failure isolation (no whole-batch abort).
• backward compatible (single-add paths untouched).
• no schema change.
• issues MCP initialize response uses snake_case (protocol_version/server_info) instead of camelCase — rejected by strict clients #52 and Add batch endpoint for memories (HTTP + MCP + CLI) #53 referenced.

Fixes #52 #53

[savioruz]

Review of PR #59 at 3ee6ec7d591cf50aa65ee16f1bbcf2ab68257d29 (base main), spanning 2 commits: 92a6aad ("serialize MCP InitializeResult", #52) and 3ee6ec7 ("batch memory support", #53).

🔴 Blocking

None. CI green (cargo build, clippy, fmt, test, audit all pass).

🟡 Warning #1 — MCP batch duplicates core add_memories_batch rather than delegating

crates/memayu-mcp/src/tools/add_memory.rs batch path loops backend.add_memory(user_id, content) per item and rolls its own success/failure summary, while memayu-core::MemoryService::add_memories_batch already implements the same per-item ADD/UPDATE+dedupe pipeline with BatchItemResult. The MCP batch therefore does not go through the service batch (it uses its own per-call embedding/dedupe loop). Not a correctness bug (both paths are equivalent today), but it is duplicated logic that can drift — ideally the MCP layer calls add_memories_batch if/when its MemoryBackend gains a batch method. Low priority; flag for follow-up.

Validation

MCP InitializeResult serialization (#52, commit 92a6aad)

• crates/memayu-mcp/src/types.rs: InitializeResult, ServerInfo, ServerCapabilities (and nested types) now #[derive(Serialize)] + #[serde(rename_all = "camelCase")]. protocol_version→protocolVersion, server_info→serverInfo, nested tools.listChanged all camelCase per MCP 2024-11-05 spec.
• New #[cfg(test)] mod tests asserts the serialized JSON keys are camelCase including nested capabilities.tools.listChanged, and that server_info.name == "memayu-mcp" + version 0.1.0. Strict clients (Claude Code) that previously rejected the snake_case payload will now accept it.

Batch memory support (#53, commit 3ee6ec7)

Core (memayu-core/src/service.rs):

• BatchMemory { content, metadata } + BatchItemResult::Stored/{ memory_id } | Failed/{ error }, both re-exported from lib.rs.
• MemoryService::add_memories_batch(user, &[BatchMemory]) -> Result<Vec<BatchItemResult>>: loops items through the existing add_memory (so ADD/UPDATE + dedupe still runs per item); per-item Err is caught into BatchItemResult::Failed, only an empty batch short-circuits with CoreError::InvalidInput("batch must contain at least one memory"). New CoreError::InvalidInput(String) variant.

HTTP API:

• DTOs in modules/memory/dto.rs: AddMemoriesBatchRequest { memories: Vec<AddMemoryItem> }, AddMemoryItem { content, metadata }, BatchMemoryError { index, error }, AddMemoriesBatchResponse { status, added, memory_ids, errors }.
• Handler add_memories_batch → POST /api/memories/batch (registered in routes.rs): 400 on empty memories; per-item failure → BatchMemoryError { index } (zero-based request index); HTTP 200 even when some items fail (graceful degradation — caller inspects errors[]).

MCP (tools/add_memory.rs):

• add_memory schema gains optional memories array ({ content, metadata }); per-item failures summarized as item {i}: <error>, successes counted; single-content path unchanged → backward compatible.

CLI (bin/memayu/src/cli.rs): add --batch / memayu batch style invocation, per-item error summary to stderr.

Tests

• crates/memayu-api/tests/api.rs: add_memories_batch_stores_all (3 valid → added:3, memory_ids.len()==3, errors==[], HTTP 200) and add_memories_batch_reports_per_item_errors (3 items, 1 empty-content → added:2, errors non-empty, still HTTP 200).
• bin/memayu/tests/cli.rs: add_batch_stores_all_items, add_batch_reports_partial_failures.
• crates/memayu-mcp/src/types.rs: ser/serde + camelCase correctness assertions incl. nested listChanged.

Breaking surface / migration

• No DB schema change.
• HTTP API backward compatible (single POST /api/memories/add untouched; /batch is new).
• MCP MemoryBackend trait is unchanged (no batch method added — MCP loops client-side).
• CLI batch is additive.

Checklist

• MCP initialize response uses snake_case (protocol_version/server_info) instead of camelCase — rejected by strict clients #52 (camelCase MCP InitializeResult) — strict-client compatible.
• Add batch endpoint for memories (HTTP + MCP + CLI) #53 batch endpoint across HTTP API + MCP + CLI.
• per-item failure isolation (no whole-batch abort).
• backward compatible (single-add paths, MCP schema, trait unchanged).
• no schema change.
• issues MCP initialize response uses snake_case (protocol_version/server_info) instead of camelCase — rejected by strict clients #52 and Add batch endpoint for memories (HTTP + MCP + CLI) #53 tagged; both remain open (auto-close on merge via the Fixes #52 #53 trailer in the PR body).

Note: PR description updated pre-review (added the two-Commit split, issue refs, checklist, and the #52/#53 issue titles).