# Memory MCP Strategic Guidelines

This document outlines the STRATEGY, SEMANTICS, and CASING STANDARDS for using the MCP Memory Server.
You do not need to memorize JSON schemas for these tools; they are strictly defined and typed in the `tools/list` endpoint. Focus purely on WHEN and WHY to use them.

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## 1. Casing & Naming Standards (CRITICAL)

To prevent graph fragmentation and ensure seamless LLM context retrieval:
* **Entity Types (`entity_type`)**: MUST ALWAYS be **`PascalCase`** (e.g. `DatabaseTable`, `McpTool`, `ArchitectureComponent`, `File`, `DataStructure`).
* **Relation Types (`relation_type`)**: MUST ALWAYS be **`snake_case`** (e.g. `depends_on`, `calls`, `implements`, `uses`, `contains`).
* **Field Keys & Properties**: MUST ALWAYS be **`snake_case`** (e.g. `file_path`, `git_commit`, `created_at`).
* **Relation Tool Parameters**: `create_relations` supports Serde field aliases (`source` -> `from`, `target` -> `to`, `relationType`/`type` -> `relation_type`) so LLM tool calls succeed seamlessly regardless of parameter naming.

> [!NOTE] 
> The server automatically enforces and migrates incoming entity and relation types to these canonical casing rules on every read and write operation.
> Store operations enforce atomic lock scope for serialization/deserialization and enter Quarantine Mode upon database corruption to prevent data overwrite hazards.

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## 2. Consolidated Smart Tools Architecture

> [!IMPORTANT] The Two-Tier Context Paradigm
> * **Tier 1 (Static Markdown)**: Repository rules, constraints, architectural patterns, and developer preferences are maintained directly in static git-tracked files (`rules/*.md`, `instructions.md`) and system prompts. This guarantees 0ms turn-0 availability without relying on proactive agent tool retrieval.
> * **Tier 2 (Telemetry & Ephemeral DB)**: High-frequency operational history—the Code Change Ledger (`audit_ledger`), terminal command history, compiler error fixes (`log_error_fix`), active tasks, and preflight context—is handled by the MCP Memory Server and surfaced via the Brain Monitor Web UI and MCP resources.


The server consolidates granular single-purpose tools into domain-named smart tools. Always prefer the consolidated tools over legacy aliases:

* **`tasks`**: Complete task lifecycle management.
  - `action: "add"`: Create a new task (requires `title`, optional `description`, `git_branch`, `repo_name`, `priority: "low" | "medium" | "high" | "urgent"`, `assigned_agent`, `verification_command`, `parent_id`, `dependencies`).
  - `action: "update"`: Update task status (requires `id`, `status: "pending" | "completed" | "cancelled"`).
  - `action: "delete"`: Delete task and child tasks (requires `id`).
  - `action: "list"`: List active tasks (optional `git_branch`, `summary_level: "compact" | "detailed" | "full"`, `max_tokens`).
  - `action: "set_criteria"`: Set acceptance criteria (requires `id`, `criteria: Vec<String>`).
  - `action: "verify"`: Verify criteria met (requires `id`, optional `proof`).

* **`milestones`**: Milestone tracking.
  - `action: "add"`: Create milestone (requires `title`, optional `namespace`, `target_date`, `description`, `deliverables: Vec<String>`, `repo_name`).
  - `action: "update"`: Update milestone status (requires `id`, `status: "active" | "completed" | "cancelled"`).
  - `action: "list"`: List milestones (optional `namespace`).

* **`sticky_notes`**: Ephemeral scratchpad notes with TTL.
  - `action: "add"`: Add note (requires `content`, optional `ttl_seconds`, `session_only`).
  - `action: "read"`: Read all active notes.
  - `action: "delete"`: Delete note by index (requires 1-based `index`).
  - `action: "clear"`: Clear all sticky notes.

* **`handoff_memos`**: Session handoff notes for future agents.
  - `action: "leave"`: Leave a memo (requires `content`, optional `vcs_revision`, `repo_name`, `git_branch`, `blockers: Vec<String>`, `action_items: Vec<String>`, `expires_at`).
  - `action: "read"`: Read active handoff memos.
  - `action: "clear"`: Clear memos.

* **`pinned_files`**: Focus file working set.
  - `action: "pin"`: Pin file to focus set (requires `path`, optional `pin_reason`, `symbol_or_line`, `repo_name`, `git_branch`).
  - `action: "unpin"`: Unpin file from focus set (requires `path`).
  - `action: "list"`: List pinned files (optional `namespace`).

* **`context_workspaces`**: Workspace context state snapshots.
  - `action: "save"`: Save context workspace (requires `name`, optional `pinned_files`, `active_task_ids`, `description`, `git_branch`, `vcs_revision`, `repo_name`).
  - `action: "load"`: Restore saved context workspace (requires `name`).
  - `action: "list"`: List saved context workspaces.
  - `action: "delete"`: Delete saved context workspace (requires `name`).
  - `action: "diff"`: Compare two saved context workspaces (requires `name`, `other_name`).

* **`pr_checklist`**: Pre-commit and PR checklist.
  - `action: "add"`: Add checklist item (requires `description`, optional `category: "Security" | "Testing" | "Formatting" | ...`, `automated_check`, `is_checked`, `repo_name`).
  - `action: "get"`: Get PR checklist items.
  - `action: "clear"`: Clear PR checklist.

* **`snippets`**: Reusable code snippet vault.
  - `action: "store"`: Store snippet (requires `query` as name, optional `language`, `code`, `description`, `tags`, `origin_file`, `line_range`, `repo_name`).
  - `action: "search"`: Search snippet vault (optional `query`, `tags`, `hybrid: true`).
  - `action: "delete"`: Delete snippet (requires `id`).
  - `action: "tag"`: Attach classification tags (requires `id`, `tags: Vec<String>`).

* **`decisions`**: Architectural Decision Records (ADRs).
  - `action: "log"`: Log ADR (requires `title`, optional `status: "accepted" | "proposed" | "deprecated" | "superseded"`, `context`, `decision`, `consequence`, `author`, `affected_components: Vec<String>`, `alternatives_considered: Vec<String>`, `supersedes`, `repo_name`).
  - `action: "query"`: Query ADRs (optional `query`).
  - `action: "delete"`: Delete ADR (requires `id`).

* **`tech_debt`**: Engineering debt backlog.
  - `action: "log"`: Log debt item (requires `description`, optional `ideal_solution`, `file_path`, `line_range`, `workaround`, `effort_estimate`, `severity: "low" | "medium" | "high" | "critical"`, `git_commit`, `git_branch`, `symbol_references`, `repo_name`).
  - `action: "resolve"`: Resolve debt item (requires `id`).
  - `action: "list"`: List debt items (optional `include_resolved`).

* **`environment`**: Infrastructure and requirements tracking.
  - `action: "update_fingerprint"`: Update tool versions (requires `tool_versions: Map<String, String>`, optional `repo_name`).
  - `action: "read_fingerprint"`: Read tool versions fingerprint.
  - `action: "log_requirement"`: Log environment variable requirement (requires `key`, `description`, `is_secret`, optional `default_value`, `validation_regex`, `repo_name`).
  - `action: "register"`: Register target environment (requires `name`, `url`, optional `description`, `requires_vpn`, `env_type: "dev" | "staging" | "qa" | "prod"`, `healthcheck_endpoint`, `ssh_host`, `repo_name`).
  - `action: "get_details"`: Read full environment details.

* **`clipboard`**: OS Clipboard management.
  - `action: "read"`: Read OS clipboard.
  - `action: "write"`: Write text/html/files/image to clipboard.
  - `action: "toggle_watch"`: Toggle auto-clipboard watcher.

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## 3. VCS & SVN Agnosticism & Multi-Repo Provenance

To support diverse enterprise repositories (Git, Subversion / SVN, Mercurial / Hg, Monorepos):
* **`vcs_type`**: Designates the VCS engine (`"git"`, `"svn"`, `"hg"`, `"perforce"`, or `"none"`).
* **`vcs_revision`**: Agnostic commit hash or SVN revision identifier (e.g., `"r12458"`, `"3e4f7a9"`).
* **`upstream_url`**: Canonical remote repository URL (e.g. `https://svn.corp/repo/trunk`, `git@bitbucket.org:org/repo.git`).
* **`repo_name`**: Logical project or repository identifier allowing multiple repositories to share or partition memory namespaces cleanly without collision.
* **Audit Ledger (`log_code_change`)**: Enriched with `vcs_type`, `vcs_revision`, `upstream_url`, `author`, `diff_summary`, and extensible `metadata: HashMap<String, String>`.

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## 4. Terminal & Process Telemetry

The server ingests and tracks active terminal commands and sessions:
* **Active Terminals**: Tracks PIDs, shell interpreters (`pwsh`, `bash`, `nu`, `zsh`), current working directories (`cwd`), command exit codes, and timestamps.
* **Terminal History Endpoint**: `/terminal/history` exposes recent shell commands and output streams to dashboard and LLMs to prevent lost shell context.
* **Quality Gate Enforcement**: `GateRecord` captures pre-flight and pre-push validation passes with `gate_type`, `enforcer`, `status`, `validation_log`, and `repo_name`.

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## 4. High-Signal Tool Responses & Performance Guidelines

To optimize context usage, response times, and LLM reasoning efficiency:

* **High-Signal Feedback**:
  - MCP tool calls (such as `create_entities`, `create_relations`, `add_observations`, `pin_file`) return explicit, structured summaries containing created names, types, edge counts, and relation paths.
  - LLMs do NOT need to execute follow-up `open_nodes` calls merely to confirm successful creation.

* **Batch Operations**:
  - When creating or updating multiple entities, snippets, or observations, always batch items into a single tool call array (e.g. `create_entities` with multiple array items) rather than making separate calls.
  - The server handles batch store mutations serially in a single transaction pass with single-permit event-driven flushes.

* **Real-time Tantivy Search Indexing**:
  - The Tantivy search engine automatically checks pending commits and reloads search readers prior to executing `omni_search` or `search_nodes`. Search queries always return up-to-date document results immediately following mutations.
  - Single-item deletions use targeted document removal rather than global index wipes.

* **Real-Time AST & Workspace Source Code Symbol Scanning**:
  - `find_symbol_references`, `get_callers`, and `analyze_impact` scan both stored code snippets and physical workspace source code files on disk (`.rs`, `.ts`, `.py`, `.go`, `.java`, `.c`, `.cpp`), providing accurate AST symbol references and call site tracking.

* **Graph Entity Merge & Self-Loop Protection**:
  - `merge_entities` re-points all relations from `source_entity` to `target_entity` and automatically prunes cyclic self-loops (`target -> target`).

* **Safe UTF-8 Token Truncation**:
  - Large responses (e.g. `get_active_worktree_context`, `read_graph`, `summarize_subgraph`) are safely truncated along UTF-8 character boundaries (`floor_char_boundary`), ensuring response bounds without runtime panics.

## 4. Automated Error Fix Auto-Matcher
- **Tools:** `log_error_fix`, `search_error_fixes` (and alias `suggest_error_fix`)
- **When to use:** When encountering a build error, test failure, or stack trace. Call `search_error_fixes` with either a text `query` or `stack_trace` before attempting a fix from scratch.
- **Behavior:** Computes cosine similarity between error trace embeddings and past resolution logs when `stack_trace` is provided, or keyword filtering when `query` is provided, returning top matched solutions, modified files, and git commits.

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## 5. Memory State Checkpointing & Rollbacks
- **Tool:** `checkpoint_state`, `restore_state` (or `create_snapshot`, `restore_snapshot`)
- **When to use:** Before initiating a large refactor, running experimental subagent tasks, or executing destructive batch operations.
- **Behavior:** Saves or restores a point-in-time snapshot of graph entities, active tasks, and tech debt backlogs.

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## 6. Self-Healing Graph Health Sweeper
- **Tool:** `sweep_graph_health`
- **When to use:** Periodically or before committing major graph changes to audit entity consistency.
- **Behavior:** Detects orphaned nodes (0 relations), computes name similarity using pre-computed lowercase keys to identify near-duplicates (e.g., `APIGateway` vs `ApiGateway`), and provides structured `merge_entities` recommendations or auto-prunes orphans.

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## 7. Causal Lineage & Provenance Tracker
- **Tool:** `query_lineage`
- **When to use:** When asking *"Why was this component modified?"* or *"What task or ADR led to this code change?"*
- **Behavior:** Searches across tasks, ADRs, audit ledger entries, and error fixes to assemble a unified chronological timeline explaining the provenance behind any file, symbol, or commit.

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## 9. Native Rust Invariants & Subprocess Prohibition (CRITICAL)

To maintain maximum security, speed, and cross-platform reliability:
* **Zero Subprocess Fallbacks**: System and server tools (`clipboard`, `ast`, `search`, `db`) MUST strictly use pure native Rust crates (`arboard`, `tree-sitter`, `tantivy`, `psycopg`). Invocations of external shell commands (`powershell.exe`, `wl-paste`, `xclip`, `cmd.exe`) are strictly prohibited in native handlers.
* **Transient Lock Recovery**: Transient OS handle collisions (such as Win32 OLE `OpenClipboard` lock contention) must be handled using native retry loops with backoffs directly in Rust.
* **Automated Static Regression Gates**: Automated AST/source audit tests (e.g. `test_no_subprocess_clipboard_regression`) verify at test time that forbidden subprocess patterns are absent from handler implementations.

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## 10. High-Performance Concurrency & Resilience Guarantees
* **Explicit Fail-Fast Persistence Safety**: Replaced silent fallback to temporary databases (`/tmp/mcp_store_fallback_*`) with an explicit open retry and fail-fast panic unless `MCP_ALLOW_TMP_FALLBACK=1` is explicitly set, preventing silent data loss.
* **Async Mutex Deadlock Elimination**: Converted shared state and Neovim connection locks (`shutdown_tx`, `NVIM_CONN`, `ACTIVE_SOCKET`, `HEADLESS_PROC`) to `tokio::sync::Mutex` to prevent worker thread pool starvation across `.await` points.
* **Telemetry Session Deduplication & Channel Pruning**: Added `LAST_SESSION` in-memory state deduplication for UDP telemetry writes (eliminating disk I/O thrashing) and distinguished WebSocket `TrySendError::Full` backpressure vs `TrySendError::Closed` client pruning.
* **Graph Adjacency Indexing**: Leverages `KnowledgeGraph::build_adjacency_map` to build $O(1)$ lookup adjacency lists for fast BFS shortest path graph queries.
* **Atomic Store Write Lock Minimization**: `Store::modify` and `Store::modify_async` release write guards immediately after in-memory state mutations, serializing JSON payloads under read locks to allow non-blocking concurrent readers.
* **Async Commit Index Reader Auto-Reload**: `MemoryIndex::commit()` automatically triggers `reader.reload()` upon completing background commits, guaranteeing immediate visibility of newly indexed document terms.
* **Zero-Allocation NDJSON Reader**: `mcp-stdio` reclaims line buffers via `std::mem::take` and in-place trimming to eliminate heap allocations during high-frequency NDJSON message parsing.
* **Dynamic Character Micro-Batched Fastembed Inference**: `generate_embeddings_async` dynamically batches text arrays using a 16,000 character budget ceiling inside `spawn_blocking`, preventing heap spikes during vector indexing while keeping ONNX SIMD execution saturated.
* **Bounded Telemetry Detail Records**: Activity and terminal telemetry buffers enforce a 4,000 character truncation ceiling on log details (`ActivityRecord`, `TerminalHistory`) to prevent unbounded RAM growth under high RPC throughput.
* **Zero-Allocation Stream Formatting**: Graph condensation loops (`condense_graph_worker`) format node/relation subgraphs into stream buffers via `std::fmt::Write`, eliminating intermediate String allocation overhead.
* **Single-Handle OS Clipboard Retries & Image Downsampling**: `WriteClipboardHandler` initializes OS clipboard handles once per operation and downsamples images exceeding $2048 \times 2048$ resolution before writing raw RGBA bytes.
* **Zero Transaction Drop Persistence Guarantee**: `Store::modify` automatically spawns an async task to execute `push_async` with channel backpressure if `push` encounters queue saturation, ensuring zero data loss under spike write loads.
* **Non-Blocking Read Lock Sticky Notes**: `StickyNotesHandler` (`action = "read"`) queries notes using shared read locks, executing write pruning only when expired items exist.
* **Token-Budgeted Query Projections**: Decision queries (`query_decisions`) support `limit` caps and compact `include_body: false` projections for token budget optimization.
* **Serde Parameter & Enum Ergonomics**: Action enums (`StickyNoteAction`, `SnippetSearchMode`, `Relation`) support case-insensitive variants and common synonyms (`create`/`add`, `remove`/`delete`, `list`/`read`, `source`/`from`, `target`/`to`, `relationType`/`relation_type`) ensuring seamless LLM tool execution.
* **Atomic Search Index Swaps**: `MemoryState::rebuild_index` constructs and populates a new `MemoryIndex` instance in isolation before performing an atomic pointer swap (`*self.search_index.write().await = new_idx`), eliminating transient empty search result windows.
* **Non-Blocking Tantivy Search Queries**: `MemoryIndex::search` queries current index searcher snapshots without executing synchronous disk commit locks, preventing query stalls during heavy background indexing.
* **Zero-Allocation HashSet<&str> Snippet Deduplication**: `indexer.rs` utilizes borrowed `HashSet<&str>` name lookups during snippet batch modifications, eliminating heap string re-allocations inside the store write lock.
* **AST Recursion Depth Safeguard & Zero-Copy Borrowing**: Tree-sitter AST traversal caps recursion depth at 100 to prevent thread stack overflows and borrows string slices (`&str`) during AST node walking.
* **Strongly-Typed SearchResult & Pre-Allocated Search Vectors**: `search.rs` uses a strongly-typed `SearchResult` struct with named fields and pre-allocates result vector capacity (`Vec::with_capacity(top_docs.len())`).
* **BFS Graph Traversal Pre-allocation & Visited Node Upper Bound**: `GraphQueryBuilder::find_shortest_path` pre-allocates adjacency map capacity (`HashMap::with_capacity(relations.len() * 2)`) and enforces a visited node upper bound (10,000 max) to guarantee deterministic BFS runtime.
* **LLM Tool Schema Ergonomics & Context Guidance**: `ReadGraphHandler` schema explicitly instructs LLMs on `namespace` filtering and `search_nodes` / `get_subgraph` tools for large graph discovery.
* **Filesystem Event Debouncing & Proactive State Refresh**: `spawn_watcher` implements a sliding 250ms debouncing window per file path, ignores `.git`, `target`, `.gemini`, and `node_modules`, and broadcasts activity events to `MemoryState`.
* **Buffered Line-by-Line AST Workspace Symbol Scanning**: `scan_workspace_for_symbol` reads workspace files via `BufReader` line streams instead of loading entire files into heap strings, preventing memory spikes when traversing source trees.
* **AST Node Type Aliasing & Skeleton Preallocation**: `replace_ast_node` documents friendly node aliases (`function`, `fn`, `method`, `struct`, `class`, `enum`, `trait`, `type`), and `read_file_skeleton` preallocates string buffer capacity (`code.len() / 2`).
* **Batch Vector Indexing & Similarity Score Guidance**: `VectorDB` provides `index_documents_batch` for single-request multi-point vector upserts and explicit score calibration notes ($\ge 0.75$ high confidence match).
* **Compact JSON MCP Resources & UTF-8 Activity Truncation**: MCP resources serialize using compact JSON (`to_string`), `TerminalHistoryResource` / `MilestonesResource` enforce output bounds, and `format_tool_activity_description` uses `floor_char_boundary` for guaranteed UTF-8 safety.
* **SIMD-Friendly Single-Pass Cosine Similarity**: `cosine_similarity` calculates dot product and Euclidean norm squares in a single linear pass over float vectors, enabling SIMD compiler auto-vectorization.
* **Safe Stream Decoding on Log Tails**: Log tail operations (`get_recent_logs`) read raw bytes and decode using lossy UTF-8 conversion (`String::from_utf8_lossy`) to ensure resilience when seeking across multi-byte UTF-8 boundaries.
* **Task Summary UTF-8 Truncation Safety**: `tasks` tool (`action = "list"`) truncates serialized task text strictly along UTF-8 character boundaries using `floor_char_boundary` when enforcing `max_tokens`.
* **Sequential Snapshot Lock Scope Flattening**: `GenerateStandupReportHandler` reads `tasks`, `ledger`, and `session_summaries` sequentially rather than nesting read locks, preventing multi-lock deadlocks during concurrent store modifications.
* **Directory Tree Depth Safeguard**: `ReadDirectoryArchitectureHandler` caps directory recursion at depth 10 to prevent stack overflow on deep or cyclic directory structures.
* **Deterministic Total-Order Score Ranking**: `OmniSearchHandler` uses `f64::total_cmp` for Reciprocal Rank Fusion (RRF) score sorting, guaranteeing deterministic NaN-safe search result ordering.
* **RPC Timeout Memory Hygiene**: `nvim-core` maintains request hygiene by removing pending request entries from static RPC maps upon timeout or channel drop, eliminating orphan memory leaks.
* **Embedding Input Safeguard**: `generate_embedding_async` returns explicit errors for empty/0-length text inputs instead of returning empty vectors, preventing downstream vector dimension mismatches during cosine similarity calculations.
* **Path Traversal Security Guards**: `validate_safe_path` enforces path canonicalization and rejects relative parent traversal components (`..`) across file and process log handlers (`GetRecentLogsTool`, `WatchProcessLogsTool`).
* **Watcher Map Memory Eviction**: Proactive daemon file watcher in `watcher.rs` caps `last_processed` map size at 1,000 entries and purges entries older than 10 minutes to prevent monotonic memory leakage.
* **Comprehensive Serde Casing Aliases**: All 11 consolidated tool action enums (`TaskAction`, `MilestoneAction`, `PinnedFileAction`, `ContextWorkspaceAction`, `PrChecklistAction`, `SnippetAction`, `DecisionAction`, `TechDebtAction`, `EnvAction`, `ClipboardAction`, `HandoffMemoAction`) include serde alias attributes supporting `snake_case`, `camelCase`, `PascalCase`, and uppercase variants for maximum LLM casing resilience.
* **Two-Phase Graph Condensation**: `condense_graph_worker` uses a 2-phase commit (non-destructive `read_with` -> graph insert -> prune by timestamp/content) to prevent data loss if summarization or graph insertion fails.
* **Store Write Lock Minimization**: `Store::modify` and `Store::modify_async` unblock concurrent readers during JSON serialization by releasing the write lock immediately after mutating memory state.
* **Redb Database Lock Retry Backoff**: `init_db` retries transient Redb lock contention with exponential backoff (3 attempts, 150ms delay) before falling back.
* **Offloaded Background Index Rebuilds**: `MemoryState::rebuild_index` offloads graph snapshot cloning and Tantivy document re-indexing into `tokio::task::spawn_blocking` to avoid stalling async event loops.
* **Broadcast Watch-Based Shutdown Channels**: Background workers utilize `tokio::sync::watch` for broadcast shutdown notifications without consuming cancellation signals.
* **Consolidated Neovim Tool Suite (v2)**: The Neovim server exposes 7 consolidated domain tools (`nvim_buffer`, `nvim_window`, `nvim_view`, `nvim_diagnostics`, `nvim_visual`, `nvim_execute_lua`, `nvim_system`) with comprehensive action dispatching.
* **Fallback Vector Search Parity**: In-memory vector search fallback indexes Knowledge Graph entities, observations, and error fixes when external vector databases are unavailable.