owlen/docs/CHANGELOG_v1.0.md

# Changelog for v1.0.0 - MCP-Only Architecture

## Summary

Version 1.0.0 marks the completion of the MCP-only architecture migration, removing all legacy code paths and fully embracing the Model Context Protocol for all LLM interactions and tool executions.

## Breaking Changes

### 1. Removed Legacy MCP Mode

**What changed:**
- The `[mcp]` section in `config.toml` no longer accepts a `mode` setting
- The `McpMode` enum has been removed from the configuration system
- MCP architecture is now always enabled - no option to disable it

**Migration:**
```diff
# old config.toml
[mcp]
-mode = "legacy"  # or "enabled"

# new config.toml
[mcp]
# MCP is always enabled - no mode setting needed
```

**Code changes:**
- `crates/owlen-core/src/config.rs`: Removed `McpMode` enum, simplified `McpSettings`
- `crates/owlen-core/src/mcp/factory.rs`: Removed legacy mode handling from `McpClientFactory`
- All provider calls now go through MCP clients exclusively

### 2. Updated MCP Client Factory

**What changed:**
- `McpClientFactory::create()` no longer checks for legacy mode
- Automatically falls back to `LocalMcpClient` when no external MCP servers are configured
- Improved error messages for server connection failures

**Before:**
```rust
match self.config.mcp.mode {
    McpMode::Legacy => { /* use local */ },
    McpMode::Enabled => { /* use remote or fallback */ },
}
```

**After:**
```rust
// Always use MCP architecture
if let Some(server_cfg) = self.config.mcp_servers.first() {
    // Try remote server, fallback to local on error
} else {
    // Use local client
}
```

## New Features

### Test Infrastructure

Added comprehensive mock implementations for testing:

1. **MockProvider** (`crates/owlen-core/src/provider.rs`)
   - Located in `provider::test_utils` module
   - Provides a simple provider for unit tests
   - Implements all required `Provider` trait methods

2. **MockMcpClient** (`crates/owlen-core/src/mcp.rs`)
   - Located in `mcp::test_utils` module
   - Provides a simple MCP client for unit tests
   - Returns mock tool descriptors and responses

### Documentation

1. **Migration Guide** (`docs/migration-guide.md`)
   - Comprehensive guide for migrating from v0.x to v1.0
   - Step-by-step configuration update instructions
   - Common issues and troubleshooting
   - Rollback procedures if needed

2. **Updated Configuration Reference**
   - Removed references to legacy mode
   - Clarified MCP server configuration
   - Added examples for local and cloud Ollama usage

## Bug Fixes

- Fixed test compilation errors due to missing mock implementations
- Resolved ambiguous glob re-export warnings (non-critical, test-only)

## Internal Changes

### Configuration System

- `McpSettings` struct now only serves as a placeholder for future MCP-specific settings
- Removed `McpMode` enum entirely
- Default configuration no longer includes mode setting

### MCP Factory

- Simplified factory logic by removing mode branching
- Improved fallback behavior with better error messages
- Test renamed to reflect new behavior: `test_factory_creates_local_client_when_no_servers_configured`

## Performance

No performance regressions expected. The MCP architecture may actually improve performance by:
- Removing unnecessary mode checks
- Streamlining the client creation process
- Better error handling reduces retry overhead

## Compatibility

### Backwards Compatibility

**Breaking:** Configuration files with `mode = "legacy"` will need to be updated:
- The setting is ignored (logs a warning in future versions)
- User config has been automatically updated if using standard path

### Forward Compatibility

The `McpSettings` struct is kept for future expansion:
- Can add MCP-specific timeouts
- Can add connection pooling settings
- Can add server selection strategies

## Testing

All tests passing:
```
test result: ok. 29 passed; 0 failed; 0 ignored
```

Key test areas:
- Agent ReAct pattern parsing
- MCP client factory creation
- Configuration loading and validation
- Mode-based tool filtering
- Permission and consent handling

## Upgrade Instructions

See [Migration Guide](migration-guide.md) for detailed instructions.

**Quick upgrade:**

1. Update your `~/.config/owlen/config.toml`:
   ```bash
   # Remove the 'mode' line from [mcp] section
   sed -i '/^mode = /d' ~/.config/owlen/config.toml
   ```

2. Rebuild Owlen:
   ```bash
   cargo build --release
   ```

3. Test with a simple query:
   ```bash
   owlen
   ```

## Known Issues

1. **Warning about ambiguous glob re-exports** - Non-critical, only affects test builds
2. **First inference may be slow** - Ollama loads models on first use (expected behavior)
3. **Cloud model 404 errors** - Ensure model names match Ollama Cloud's naming (remove `-cloud` suffix from model names)

## Contributors

This release completes the Phase 10 migration plan documented in `.agents/new_phases.md`.

## Related Issues

- Closes: Legacy mode removal
- Implements: Phase 10 cleanup and production polish
- References: MCP architecture migration phases 1-10