## ADDED Requirements

### Requirement: Pack layout
A course pack SHALL be a zip archive whose root contains `manifest.json` and a `media/` directory with the media files required by that course. An optional cover image MAY be omitted in MVP.

#### Scenario: Minimal pack contents
- **WHEN** a pack is produced for a valid combo course
- **THEN** extracting the zip yields `manifest.json` and the media files referenced by the manifest under `media/`

### Requirement: Manifest schema
The `manifest.json` SHALL include `schemaVersion`, stable course `id`, `title`, `mode` (`combo`), `updatedAt`, `items` (album items compatible with desktop combo semantics), and a `resources` array mapping resource ids to relative media paths and kinds (`video` | `audio` | `pdf`).

#### Scenario: Resources cover all item references
- **WHEN** a manifest lists combo items with resource ids
- **THEN** every referenced resource id appears in `resources` with a path that exists inside the pack

### Requirement: iPad local course storage
After a successful download, the iPad app SHALL store the unpacked pack under an app-sandbox courses directory keyed by course id and SHALL persist a local course record so the course appears as downloaded.

#### Scenario: Downloaded course is local
- **WHEN** a pack is downloaded and validated
- **THEN** `manifest.json` and media exist under the local courses directory for that id AND a local course record is available to the home deck

### Requirement: Reject invalid packs
The iPad app MUST NOT register a local course when `manifest.json` is missing, unreadable, or fails basic validation (missing id/title/items/resources), or when the zip cannot be extracted successfully.

#### Scenario: Corrupt or unreadable zip rejected
- **WHEN** a download completes but the archive cannot be unzipped or lacks a valid manifest
- **THEN** the app does not add a home-deck course and surfaces an error

### Requirement: Update existing course
When downloading a course whose id already exists locally with a newer `updatedAt`, the app SHALL replace the local pack contents and update the local course record.

#### Scenario: Newer pack overwrites
- **WHEN** the user downloads course id X and the pack `updatedAt` is newer than the local copy
- **THEN** local media and manifest for X are replaced with the new pack contents