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Author: shuv1337

CONTEXT/CONFIG_API_UPDATES.md

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+# Config API Updates Summary
+
+## Overview
+
+The PATCH `/config` API endpoint has been completely revamped to support both global and project-scoped configuration updates, with enhanced error handling, validation, and safety features.
+
+## Key Changes
+
+### 1. Scope Support
+
+- **New Parameter**: `?scope=global|project` (defaults to `project`)
+- **Global Config**: Updates `~/.config/opencode/opencode.jsonc`
+- **Project Config**: Updates `<project>/opencode.jsonc`
+
+### 2. File Format Migration
+
+- **From**: `config.json`
+- **To**: `opencode.jsonc` (JSON with Comments support)
+- **Note**: Project config precedence changed to prefer JSONC over JSON
+
+### 3. Enhanced Safety Features
+
+- **Permission Validation**: Checks write access before attempting updates
+- **Config Validation**: Validates merged config against schema
+- **Backup & Rollback**: Automatic backup creation and restore on failure
+- **Error Handling**: Clear, descriptive error messages
+
+## API Usage
+
+### Update Project Config (Default)
+
+```bash
+PATCH /config
+Content-Type: application/json
+
+{
+  "model": "anthropic/claude-3-sonnet",
+  "username": "myuser"
+}
+```
+
+### Update Global Config
+
+```bash
+PATCH /config?scope=global
+Content-Type: application/json
+
+{
+  "model": "anthropic/claude-3-sonnet",
+  "username": "globaluser"
+}
+```
+
+### Explicit Project Scope
+
+```bash
+PATCH /config?scope=project
+Content-Type: application/json
+
+{
+  "model": "anthropic/claude-3-sonnet"
+}
+```
+
+## Response Format
+
+### Success (200)
+
+```json
+{
+  "model": "anthropic/claude-3-sonnet",
+  "username": "myuser"
+  // ... other merged config properties
+}
+```
+
+### Error Responses
+
+#### Permission Error (400)
+
+```json
+{
+  "name": "ConfigUpdateError",
+  "message": "No write permission for global config directory: ~/.config/opencode",
+  "path": "~/.config/opencode"
+}
+```
+
+#### Validation Error (400)
+
+```json
+{
+  "name": "ConfigValidationError",
+  "message": "Invalid config after merge: Invalid field 'invalid_field'",
+  "path": "/path/to/config.jsonc"
+}
+```
+
+#### Write Error (400)
+
+```json
+{
+  "name": "ConfigUpdateError",
+  "message": "Failed to write config: ENOSPC: no space left on device",
+  "path": "/path/to/config.jsonc"
+}
+```
+
+## Implementation Details
+
+### Core Function Changes
+
+#### Config.update() Signature
+
+```typescript
+export async function update(config: Info, scope: "global" | "project" = "project"): Promise<void>
+```
+
+#### File Path Resolution
+
+```typescript
+const filepath =
+  scope === "global"
+    ? path.join(Global.Path.config, "opencode.jsonc")
+    : path.join(Instance.directory, "opencode.jsonc")
+```
+
+### Safety Mechanisms
+
+1. **Directory Creation**: Automatically creates global config directory
+2. **Permission Check**: Verifies write access before proceeding
+3. **Config Merging**: Deep merges new config with existing
+4. **Schema Validation**: Validates merged config against Zod schema
+5. **Backup Creation**: Creates `.backup` file before writing
+6. **Rollback**: Restores backup on write failure
+7. **Cleanup**: Removes backup on successful completion
+
+### Error Classes Added
+
+```typescript
+export const UpdateError = NamedError.create(
+  "ConfigUpdateError",
+  z.object({
+    message: z.string(),
+    path: z.string().optional(),
+  }),
+)
+
+export const ValidationError = NamedError.create(
+  "ConfigValidationError",
+  z.object({
+    message: z.string(),
+    path: z.string(),
+  }),
+)
+```
+
+## Testing
+
+### Test Coverage
+
+- ✅ 21 tests passing
+- ✅ 6 new tests added for new functionality
+- ✅ All existing tests updated and passing
+
+### Test Categories
+
+1. **Basic Update Tests**: Project and global config updates
+2. **Merge Tests**: Config merging with existing settings
+3. **Validation Tests**: Invalid config rejection
+4. **Error Handling Tests**: Permission and write failures
+5. **Rollback Tests**: Backup and restore functionality
+
+## Migration Guide
+
+### For API Users
+
+- **No Breaking Changes**: Existing calls continue to work (default to project scope)
+- **Optional Enhancement**: Add `?scope=global` for global config updates
+
+### For SDK Users
+
+- **New Parameter**: `update(config, scope?)` where scope is optional
+- **Default Behavior**: Unchanged (project scope)
+- **New Capability**: Can now update global config
+
+### For Client Applications
+
+- **TUI/Desktop**: Can add scope selection UI
+- **CLI**: Can add `--global` flag for global updates
+- **Web**: Can add scope dropdown in config interface
+
+## File Locations
+
+### Global Config
+
+- **Path**: `~/.config/opencode/opencode.jsonc`
+- **Created**: Automatically if doesn't exist
+- **Permissions**: Requires write access to `~/.config/opencode/`
+- **Merge Behavior**: `Config.global()` deep-merges `config.json`, then `opencode.json`, then `opencode.jsonc`, so JSONC keys override JSON while preserving unique values. Remeda's `mergeDeep` handles the merge without conflict errors, meaning both files may coexist and their contents combine into the final runtime config.
+
+### Project Config
+
+- **Path**: `<project-root>/opencode.jsonc` (or `opencode.json`)
+- **Search Order**: `opencode.jsonc` 2 `opencode.json`
+- **Fallback**: Creates `opencode.jsonc` if neither exists
+- **.opencode Folder**: For each directory from the project root up to the worktree root, if `.opencode/opencode.jsonc` exists it is merged first, otherwise `.opencode/opencode.json` is used as a fallback. This allows `.opencode` config to override root-level settings while always preferring JSONC when present.
+
+
+## Performance Considerations
+
+- **Atomic Operations**: Backup + write + cleanup ensures data integrity
+- **Efficient Merging**: Uses existing `mergeDeep` function
+- **Minimal I/O**: Only reads existing config when necessary
+- **Fast Validation**: Zod schema validation is performant
+
+## Security Considerations
+
+- **Permission Checks**: Validates write access before operations
+- **Path Validation**: Uses proper path joining to prevent directory traversal
+- **Error Sanitization**: Error messages don't expose sensitive paths
+- **Backup Security**: Backup files are cleaned up automatically
+
+## Backward Compatibility
+
+- ✅ **API Contract**: Maintained (optional parameter)
+- ✅ **Default Behavior**: Unchanged (project scope)
+- ✅ **Response Format**: Identical
+- ✅ **Error Handling**: Enhanced but compatible
+
+## Future Enhancements
+
+### Potential Improvements
+
+1. **JSONC Comment Preservation**: Currently writes formatted JSON, could preserve comments
+2. **Config Locking**: File locking for concurrent access safety
+3. **Config History**: Version history for config changes
+4. **Config Diff**: Show what changed during updates
+5. **Bulk Updates**: Update multiple config sections atomically
+
+### Integration Points
+
+1. **SDK Updates**: Update all SDKs to support scope parameter
+2. **Client Updates**: Add scope selection to TUI/desktop clients
+3. **Documentation**: Update API docs and user guides
+4. **Migration Tools**: Tools to migrate from old config.json format
+
+## Troubleshooting
+
+### Common Issues
+
+#### Permission Denied
+
+```bash
+Error: No write permission for global config directory
+Solution: Check permissions on ~/.config/opencode/
+```
+
+#### Invalid Config
+
+```bash
+Error: Invalid config after merge
+Solution: Validate config against schema before sending
+```
+
+#### Disk Space
+
+```bash
+Error: Failed to write config: ENOSPC
+Solution: Free up disk space and retry
+```
+
+### Debug Tips
+
+1. **Check Scope**: Verify you're using correct scope parameter
+2. **File Permissions**: Ensure write access to target directory
+3. **Config Validation**: Test config against schema locally
+4. **Backup Files**: Check for leftover `.backup` files after failures
+
+## Support
+
+For issues or questions about the config API updates:
+
+1. Check existing tests for usage examples
+2. Review error messages for specific guidance
+3. Consult the implementation in `packages/opencode/src/config/config.ts`
+4. Check API documentation for latest parameter details
+