tapehoard/AGENTS.md

Agent Development Guide

This file contains architectural context and conventions for AI agents (and humans) working on the TapeHoard codebase.

Project Structure

tapehoard/
├── backend/           # FastAPI + SQLAlchemy + SQLite
│   ├── app/
│   │   ├── api/       # API routers
│   │   │   ├── common.py          # Shared helpers & schemas
│   │   │   ├── system/            # System endpoints (13 modules)
│   │   │   ├── archive.py         # Archive file index endpoints
│   │   │   ├── backups.py         # Backup job endpoints
│   │   │   ├── inventory.py       # Media fleet endpoints
│   │   │   ├── restores.py        # Restore queue endpoints
│   │   │   └── schemas.py         # Shared Pydantic schemas
│   │   ├── db/
│   │   ├── services/  # Business logic (scanner, archiver, scheduler)
│   │   └── main.py    # FastAPI app factory + router registration
│   └── tests/         # Pytest suite (77 tests)
├── frontend/          # SvelteKit + TypeScript
│   ├── src/lib/api/   # Auto-generated OpenAPI SDK
│   └── tests/         # Playwright E2E suite (34 tests)
└── docs/              # Additional documentation

Backend Architecture

API Router Organization

All API routes live under app/api/. The system endpoints are split into a package (app/api/system/) with focused submodules:

Module	Endpoints
system/jobs.py	/system/jobs/*, /system/jobs/{id}/cancel, /system/jobs/{id}/retry, /system/jobs/stream
system/scan.py	/system/scan, /system/index/hash, /system/scan/status
system/filesystem.py	/system/browse, /system/search
system/tree.py	/system/tree
system/dashboard.py	/system/dashboard/stats
system/settings.py	/system/settings
system/hardware.py	/system/hardware/discover, /system/hardware/ignore
system/discrepancies.py	/system/discrepancies/*, batch ops, tree, browse
system/database.py	/system/database/export, /system/database/import
system/tracking.py	/system/track/batch
system/notifications.py	/system/notifications/test
system/host.py	/system/ls
system/test.py	/system/test/reset

Each module defines its own APIRouter with tags=["System"] and is registered in main.py with prefix="/system".

Index-Only Principle

Never rely on the live filesystem for data, except during a scan. All read endpoints must operate exclusively on the database index. The filesystem is only accessed during:

• Scan operations (/system/scan) — to discover files, compute hashes, and sync the index.
• Configuration endpoints (/system/ls, /system/browse when path is outside roots) — to help users pick source roots during setup.

Browsing the archive, searching, or checking protection status must use the index only. This guarantees consistent results even when files are temporarily inaccessible, and prevents I/O bottlenecks on network or tape-backed storage.

Shared Helpers (app/api/common.py)

Cross-cutting helpers and schemas that must not create circular imports:

• get_source_roots(db_session) → List[str]
• get_exclusion_spec(db_session) → Optional[pathspec.PathSpec]
• get_ignored_status(path, tracking_map, exclusion_spec) → bool
• _validate_path_within_roots(path, roots) → bool
• _active_job_exists(db_session, job_type) → bool
• _get_last_scan_time(db_session) → Optional[datetime]
• Shared Pydantic schemas: DashboardStatsSchema, JobSchema, JobLogSchema, FileItemSchema, BrowseResponseSchema, ScanStatusSchema, SettingSchema, TestNotificationRequest, IgnoreHardwareRequest, BatchTrackRequest

Rule: common.py must NEVER import from any API module (no app.api.system, app.api.archive, etc.). Only models, database, and standard libraries.

Endpoint Naming Convention

All FastAPI route handlers must declare explicit operation_id to control the generated TypeScript SDK names.

Pattern	Example Handler	operation_id	Generated TS
GET list	list_jobs	list_jobs	listJobs
GET one	get_job	get_job	getJob
POST create	create_media	create_media	createMedia
POST action	trigger_scan	trigger_scan	triggerScan
PATCH update	update_media	update_media	updateMedia
DELETE	delete_media	delete_media	deleteMedia
Batch actions	batch_track	batch_track	batchTrack

Never let FastAPI auto-generate operationId. The old auto-generated names looked like getDashboardStatsSystemDashboardStatsGet — verbose and brittle.

Router Prefix Rules

• Top-level domain routers (archive, backups, inventory, restores) define their own prefix in the router constructor (e.g., APIRouter(prefix="/archive")).
• system submodules use no prefix in the router constructor; main.py applies prefix="/system" when calling app.include_router().

Frontend Architecture

TypeScript SDK (frontend/src/lib/api/)

Generated from the backend OpenAPI spec using @hey-api/openapi-ts:

just generate-client

This runs the full pipeline: exports the OpenAPI spec from the running FastAPI app and regenerates the TypeScript SDK in frontend/src/lib/api/. Use this after any backend change that adds, renames, or modifies endpoints or schemas.

The generated SDK exports clean camelCase functions (e.g., getDashboardStats, listJobs, triggerScan).

Rule: After renaming any backend handler or changing an operation_id, regenerate the SDK and update all frontend imports. The old verbose names will cause TypeScript errors.

Frontend Imports to Avoid Shadowing

Some Svelte components define local functions with the same name as SDK imports (e.g., cancelJob, retryJob in jobs/+page.svelte). When this happens, alias the SDK import:

import { cancelJob as cancelJobApi, retryJob as retryJobApi } from '$lib/api';

Testing

Backend Tests

cd backend && uv run pytest tests/ -v

• 77 tests covering API endpoints, providers, services
• Uses pytest-mock for mocking filesystem/hardware
• Important: Mocks that patch get_source_roots or get_exclusion_spec must target app.api.common (not app.api.system), since those helpers moved to common.py.

Frontend E2E Tests

cd frontend && npx playwright test

• 34 Playwright tests using Chromium
• Backend test server auto-starts via playwright.config.ts webServer config
• Tests use requestContext for direct API calls + page for UI interactions

macOS IPv6 Gotcha

On macOS, localhost resolves to ::1 (IPv6) by default, but uvicorn may bind to IPv4 only. This causes ECONNREFUSED ::1:8001 in Playwright tests.

Fix: Always use 127.0.0.1 instead of localhost for backend URLs:

• frontend/tests/helpers.ts: API_URL = 'http://127.0.0.1:8001'
• frontend/playwright.config.ts: webServer.url = 'http://127.0.0.1:8001'

Common Tasks

Adding a New System Endpoint

1. Choose the appropriate app/api/system/<module>.py file (or create a new one if it doesn't fit existing categories).
2. Add the route handler with an explicit operation_id.
3. Import shared helpers from app.api.common if needed.
4. Register the new router in app/main.py with prefix="/system".
5. Regenerate the TypeScript SDK.
6. Update frontend imports if using the new endpoint.
7. Add backend tests in backend/tests/test_api_system.py (or a new test file if it's a new domain).
8. Run just lint before finishing.

Regenerating the OpenAPI Spec / TypeScript SDK

Use the convenience command:

just generate-client

Or run the steps manually:

cd backend && uv run python -c "import json; from app.main import app; json.dump(app.openapi(), open('openapi.json', 'w'), indent=2)"
cd ../frontend && npx @hey-api/openapi-ts -i ../backend/openapi.json -o src/lib/api

Verifying No Auto-Generated operationIds

cd backend && uv run python -c "
from app.main import app
import re
for path, methods in app.openapi()['paths'].items():
    for method, info in methods.items():
        op_id = info.get('operationId', '')
        if re.search(r'_(get|post|put|patch|delete)$', op_id):
            print(f'DIRTY: {method.upper()} {path} = {op_id}')
print('Check complete')
"

Lint & Format

just lint       # Runs ruff (Python) + svelte-check (TypeScript/Svelte)

Pre-commit hooks are configured but may stash unstaged changes.

Environment

• Backend: Python 3.13, FastAPI, SQLAlchemy 2.x, SQLite, uv for package management
• Frontend: SvelteKit, TypeScript, Tailwind CSS, shadcn-svelte components
• Test server: TAPEHOARD_TEST_MODE=true enables /system/test/reset and mock providers

Documentation Files

File	Contents
README.md	Human-facing project overview
AGENTS.md	This file — agent development guide