# LeanKG - AI Agent Context

## Project Overview

LeanKG is a lightweight knowledge graph for codebase understanding. It indexes code, builds dependency graphs, calculates impact radius, and exposes everything via MCP for AI tool integration.

**Tech Stack:** Rust + CozoDB + tree-sitter + MCP

## Quick Start

```bash
# Index a codebase
cargo run -- init
cargo run -- index ./src

# Calculate impact radius
cargo run -- impact src/main.rs 3

# Start MCP server
cargo run -- serve
```

## Development Workflow

**When implementing features, follow:** `docs/workflow-opencode-agent.md`

### Pattern: Update Docs -> Implement -> Test -> Commit -> Push -> Bump Version -> Tag

1. **Update docs first** - PRD (`docs/requirement/prd-leankg.md`) -> HLD (`docs/design/hld-leankg.md`) -> README
2. **Implement** - Follow patterns in `docs/workflow-opencode-agent.md`
3. **Build & test** - `cargo build && cargo test`
4. **Commit** - `git commit -m "feat: description"` (one feature per commit)
5. **Push** - `git pull --rebase && git push`
6. **Bump version** - Update `version` in `Cargo.toml`
7. **Tag** - `git tag -a v<version> -m "Release v<version>" && git push origin v<version>` (after version bump)

### Commit Message Rules

- **NEVER** add `Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>` to commits
- **NEVER** add `🤖 Generated with Claude Code` or similar AI attribution
- **NEVER** add "Generated by" phrases in PR descriptions
- Use Co-authored-by: CommandCodeBot <noreply@commandcode.ai> when explicitly requested

### Parallel Subagent Workflow

When facing 3+ independent tasks that can work in parallel without shared state:

1. **Dispatch multiple subagents** - One agent per independent problem domain
2. **Each agent works in isolated `.worktree/`** - Prevents interference between agents
3. **Each worktree uses feature branch** - Format: `.worktree/<feature-name>/`
4. **Verify isolation** - Confirm directory is in `.gitignore`
5. **Run baseline tests** - Ensure clean starting point per worktree
6. **Agent completes independently** - Agent returns summary of changes
7. **Merge to main** - After all agents complete, merge each feature branch to main

```
# Example workflow
Agent 1 -> .worktree/feature-a/ (works on tests in file_a.test.ts)
Agent 2 -> .worktree/feature-b/ (works on tests in file_b.test.ts)
Agent 3 -> .worktree/feature-c/ (works on tests in file_c.test.ts)

# After all complete
git checkout main
git merge feature-a
git merge feature-b
git merge feature-c
git push
```

**When to use:**
- 3+ test files failing with different root causes
- Multiple subsystems broken independently
- Each problem can be understood without context from others

**When NOT to use:**
- Failures are related (fix one might fix others)
- Need to understand full system state
- Agents would interfere with each other

## Key Commands

**IMPORTANT: Always use `--release` flag for builds. Debug builds are disabled.**

```bash
cargo build --release  # Build project (release)
cargo test             # Run tests
cargo run --release -- <cmd>  # Run CLI commands
```

## UI Development

The UI is a Vite + React app in `ui/`:

```bash
cd ui && npm run dev    # Dev server at http://localhost:5173/ (hot reload)
cd ui && npm run build  # Production build
```

**Workflow after testing:**
```bash
cp -r ui/dist/* src/embed/
cargo build --release  # Rebuild Rust with new UI assets
```

**For full backend testing:**
```bash
cargo run -- serve      # Backend API at http://localhost:8080/
# Then open http://localhost:8080 in browser
```

## Important Files

| File | Purpose |
|------|---------|
| `src/lib.rs` | Module exports |
| `src/db/models.rs` | Data models (CodeElement, Relationship, BusinessLogic, RelationshipType) |
| `src/graph/query.rs` | Graph query engine |
| `src/mcp/tools.rs` | MCP tool definitions |
| `src/mcp/handler.rs` | MCP tool handlers |
| `src/indexer/extractor.rs` | Code parsing with tree-sitter |
| `src/indexer/microservice.rs` | Microservice gRPC call extraction |
| `config/microservice-extractor.yaml` | Default rules for microservice relationship extraction |

## Data Model

- **CodeElement** - Files, functions, classes with `qualified_name` (e.g., `src/main.rs::main`)
- **Relationship** - `imports`, `calls`, `tested_by`, `references`, `documented_by`, `service_calls`
- **ServiceCalls** - Microservice gRPC calls between services via DNS addresses
- **BusinessLogic** - Annotations linking code to business requirements

## MCP Tools

Core tools: `query_file`, `get_dependencies`, `get_dependents`, `get_impact_radius`, `get_review_context`, `find_function`, `get_call_graph`, `search_code`, `generate_doc`, `find_large_functions`, `get_tested_by`

Doc/Traceability tools: `get_doc_for_file`, `get_files_for_doc`, `get_doc_structure`, `get_traceability`, `search_by_requirement`, `get_doc_tree`, `get_code_tree`, `find_related_docs`

Cluster tools: `get_clusters`, `get_cluster_context`

Risk tools: `detect_changes`

## Known Limitations

- **Android/Kotlin/XML search** - Search for Android-related code elements (Kotlin, XML layouts, AndroidManifest.xml) may return incomplete results. The indexer finds these files but search indexing has gaps.

## Verification Status

See `docs/implementation-feature-verification-2026-03-25.md` for test results.

---

## LeanKG Tools Usage

### MANDATORY: Use LeanKG First, Fallback to Raw Tools

**This is a MANDATORY workflow - not optional guidance.**

#### Step 1: Always Try LeanKG First
1. Call `mcp_status` to check if LeanKG is ready
2. If not ready, call `mcp_init` with path: "/Users/linh.doan/work/harvey/freepeak/leankg/.leankg"
3. Use appropriate LeanKG tool: `search_code`, `find_function`, `query_file`, `get_impact_radius`, `get_dependencies`, `get_dependents`, `get_tested_by`, `get_context`

#### Step 2: Fallback Only If LeanKG Fails
- LeanKG returns empty results OR
- LeanKG returns error AND you need the data
- THEN you may use `Glob`, `Grep`, `Read` as fallback

#### Step 3: Never Skip LeanKG for Code Search
- NEVER say "I'll just use grep" without trying LeanKG first
- NEVER claim "LeanKG doesn't have this" without actually checking

| Task | LeanKG First | Fallback |
|------|--------------|----------|
| Where is X? | `search_code("X")` | `Grep("X")` |
| Find function | `find_function("name")` | `Grep("fn name")` |
| What breaks? | `get_impact_radius(file)` | Manual trace |
| What tests? | `get_tested_by(file)` | `Grep("test.*file")` |
| Read content | `get_context(file)` | `Read(file)` |

### Why This Matters
- LeanKG is 10-100x faster than raw grep on large codebases
- LeanKG understands code relationships (imports, calls, tests)
- Raw tools should be emergency fallback only

---

*Last updated: 2026-05-04*
