Initial ForgeLM import

.planning/phases/04-model-source-validation/04-02-PLAN.md

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+# Plan 04-02: Path and Model File Validation
+
+**Wave:** 1  
+**Phase:** 4  
+**Requirements addressed:** MODL-02
+
+---
+
+## Objective
+
+Add path existence validation and model file scanning integration so users receive immediate feedback when their selected model path or models directory is invalid.
+
+---
+
+## Read First
+
+- `tauri-app/src-tauri/src/model_files.rs` — scan_models, pick_models_dir commands
+- `tauri-app/src/features/runtime/api.ts` — invoke wrappers for Tauri commands
+- `tauri-app/src/features/runtime/runtime-settings-form.ts` — RuntimeSettingsFormState, scanned models
+- `tauri-app/src/features/runtime/types.ts` — RuntimeModelFile, RuntimePickDirResult
+- `.planning/phases/04-model-source-validation/04-RESEARCH.md` — path validation patterns
+
+---
+
+## Action
+
+1. **Add Tauri command wrappers** in `api.ts`:
+
+   ```typescript
+   export interface ScannedModelsResult {
+     dir: string;
+     models: RuntimeModelFile[];
+   }
+   
+   export async function scanModelsDir(dirPath: string): Promise<RuntimeModelFile[]> {
+     return await invoke<RuntimeModelFile[]>("scan_models", { dir: dirPath });
+   }
+   
+   export async function pickModelsDirectory(): Promise<ScannedModelsResult> {
+     return await invoke<ScannedModelsResult>("pick_models_dir");
+   }
+   ```
+
+2. **Extend runtime-utils.ts with path validation**:
+
+   ```typescript
+   import { scanModelsDir } from "./api";
+   
+   export async function validateModelsDirectory(
+     path: string | null
+   ): Promise<{ valid: boolean; modelCount: number; error: string | null }> {
+     if (!path) {
+       return { valid: false, modelCount: 0, error: "No models directory selected" };
+     }
+     try {
+       const models = await scanModelsDir(path);
+       return { 
+         valid: true, 
+         modelCount: models.length, 
+         error: null 
+       };
+     } catch (e) {
+       return { 
+         valid: false, 
+         modelCount: 0, 
+         error: e instanceof Error ? e.message : String(e) 
+       };
+     }
+   }
+   
+   export async function validateModelFile(
+     path: string | null,
+     scannedModels: RuntimeModelFile[]
+   ): Promise<{ valid: boolean; exists: boolean; error: string | null }> {
+     if (!path) {
+       return { valid: false, exists: false, error: "No model selected" };
+     }
+     const exists = scannedModels.some(m => m.path === path);
+     return {
+       valid: exists,
+       exists,
+       error: exists ? null : "Model file not found in current models directory"
+     };
+   }
+   ```
+
+3. **Add model scanning to runtime-settings-form.ts**:
+
+   - Add `scannedModels: RuntimeModelFile[]` to RuntimeSettingsFormState
+   - Add `scanModels(dir: string)` function that calls api.scanModelsDir
+   - Update `resolveDraftModelSelection` to use scanned models for validation
+
+4. **Integrate into useRuntimeManager.ts**:
+
+   - Add `scannedModels` to draft state
+   - When `models_dir` field changes, trigger rescan
+   - When rescan completes, validate `model_path` against new scan results
+   - Update field validation state with path-specific errors
+
+5. **Add validation display in UI components**:
+
+   - In runtime settings form, show validation message when models_dir is invalid
+   - Show "X models found" when scan succeeds
+   - Show "Model not in directory" when selected model is invalid after scan
+
+---
+
+## Acceptance Criteria
+
+- [ ] `api.ts` exports `scanModelsDir(path)` and `pickModelsDirectory()`
+- [ ] `runtime-utils.ts` exports async validators that check directory and file existence
+- [ ] Changing `models_dir` triggers rescan and updates validation state
+- [ ] Selected model is validated against scanned models list
+- [ ] Invalid paths show clear error messages in the UI
+- [ ] User can see "X models found" feedback after scanning
+
+---
+
+## Notes
+
+- Reuse existing scan_models Rust command - no backend changes needed
+- Keep validation async to support filesystem checks
+- Show appropriate loading state during scan
+- Handle scan errors gracefully (directory not found, permission denied)