Design: Database: TID-Topic meta

Database		TID-Topic
Purpose		Hold topic details and track topic members.
Cardinality		one TID-Topic database per topic one TopicDataItem item per topic one TopicMemberItem per member invited to the topic
Source Code
	Items	src/ts/dbitems/TID-Topic.ts
Zod Models
	item	TopicItem - union of TopicDataItem, TopicMemberItem below
	item.item	one of TopicDataRecord, TopicMemberRecord
TopicDataItem
	itemId	'topicdata'
	item:	TopicDataRecord
	kind	'topicdata'
	tkey	topic key (creator concatenated with transliterated topic number)
	title	title of the topic
	description	description of topic
	path	topic path
	bundles	list of TopicBundle in load order
	mtid	MTID prefix for member MTID-Activity databases
TopicBundle
	bnum	bundle number
	include	true if bundle required by topic
TopicMemberItem
	itemId	member number invited to topic
	item:	TopicMemberRecord
	kind	'topicmember'
	tnum	this topic's topic number
	mnum	member number invited to topic (same as itemId)

Description

The TID-Topic database is created when a member creates a new topic.
It holds one TopicDataItem with the details and path for the topic and one TopicMemberItem for each member invited to discuss the topic.

  (see userbase-js/types/index.d.ts)

  export interface Item {              userbase item
    itemId: string                    ╭────────────────────────────────────┐
    item: any ────────────────────┬──▶│ kind: 'topicdata'                  │
    createdBy: Attribution        │   │ tkey: '1A'                         │
    updatedBy?: Attribution       │   │ title: 'Code Samples'              │
    fileId?: string               │   │ mtid: '01HPJFDKDXJCR2Z067PZGHF3YC' │
    fileName?: string             │   │ ...                                │            
    fileSize?: number             │   ╰────────────────────────────────────┘            
    fileUploadedBy?: Attribution  │                                         
    writeAccess?: AccessControl   └──▶╭────────────────────────────────────┐
  }                                   │ kind: 'topicmember'                │
                                      │ tnum: 1                            │
                                      │ mnum: 2                            │
                                      │ mtid: '01HPJFDKDXJCR2Z067PZGHF3YC' │
                                      ╰────────────────────────────────────┘

  TopicRecord represents the specific type of Item.item for an entry
  in the Bundles database - either TopicDataRecord or TopicMemberRecord.

TopicDataItem

The TID-Topic database holds one TopicDataItem which keeps track of the details for the topic.

The tkey attribute is the concatenation of the digits of the member number of the topic's creator and the digits of the topic number transliterated as follows

    0 1 2 3 4 5 6 7 8 9 
    │ │ │ │ │ │ │ │ │ │ 
    ▼ ▼ ▼ ▼ ▼ ▼ ▼ ▼ ▼ ▼ 
    Z A B C D E F G H J 

For example the tkey "3B" indicates the second topic (B) created by member 3.

The mtid attribute holds the prefix of each member's MTID-Activity database of comments for the topic. The mtid is a random ULID not easily guessable or derivable from other information. While a topic's tid is visible to all members of an engengement, the value of a topic's mtid is known only to the topic's members.

TopicMemberItem

The TID-Topic database holds one TopicMemberItem for each member invited to discuss the topic.

The mtid attribute holds the prefix of each member's MTID-Activity database of comments for the topic. The name of a member's MTID-Activity database is derived from the mtid for the topic and the mnum for the member.

Ownership and Access

The creator of the topic is the owner of the TID-Topic database for the topic.

The TID-Topic database shared read-only with the members of the topic.

Zod models

The following Zod models show how the Userbase items are represented in memory.

Note that in addition to the values specified by the Userbase Item interface the kind and database attributes are added during deserialization.

export type TIDTopicItem =
  | TopicDataItem
  | TopicMemberItem
;
export const TIDTopicItem = z.discriminatedUnion('kind', [
  TopicDataItem,
  TopicMemberItem
]);

TopicDataItem

export type  TopicDataItem = z.infer<typeof TopicDataItem>;
export const TopicDataItem = z.object({
  kind:                 z.literal('topicdataitem'),
  itemId:               z.string(),
  item:                 TopicDataRecord,
  updatedBy:            z.custom<Attribution>(),
  database:             z.custom<Database>()
}).strip();

export type  TopicDataRecord = z.infer<typeof TopicDataRecord>;
export const TopicDataRecord = z.object({
  kind:                 z.literal('topicdata'),
  tkey:                 z.string(),
  title:                z.string(),
  description:          z.string(),
  path:                 z.string(),
  bundles:              TopicBundle.array(),
  mtid:                 z.string()
}).strip();

export type  TopicBundle = z.infer<typeof TopicBundle>;
export const TopicBundle = z.object({
  bnum:                 z.number(),
  include:              z.boolean()
}).strip();

TopicMemberItem

export type  TopicMemberItem = z.infer<typeof TopicMemberItem>;
export const TopicMemberItem = z.object({
  kind:                 z.literal('topicmemberitem'),
  itemId:               z.string(),
  item:                 TopicMemberRecord,
  updatedBy:            z.custom<Attribution>(),
  database:             z.custom<Database>()
}).strip();

export type  TopicMemberRecord = z.infer<typeof TopicMemberRecord>;
export const TopicMemberRecord = z.object({
  kind:                 z.literal('topicmember'),
  tnum:                 z.number(),
  mnum:                 z.number()
}).strip();