feat(spec)!: retire vestigial feed contracts + protocol surface (#1959) (#3186)

ADR-0052 §5 follow-up. `service-feed`'s runtime was deleted in #1955;
`sys_comment` / `sys_activity` are the canonical record-collaboration /
timeline backend. This removes the dead type surface that still pointed at
the deleted runtime — every removed method was already unreachable (feed
REST was never mounted → 404; the protocol impl was never wired with a feed
service, so requireFeedService() could only throw). No behavior change.

Removed:
- spec: contracts/feed-service (IFeedService), api/feed-api.zod
  (FeedApiContracts + request/response types), data/subscription.zod, and the
  four feed regions of api/protocol.zod (imports, z.function stubs, type
  re-exports, FeedProtocol interface + mixin) — plus their tests and barrels.
- metadata-protocol: the getFeedService ctor param, requireFeedService(), and
  the 14 feed method implementations. Constructor is now
  (engine, getServicesRegistry?, environmentId?).
- objectql: protocol-feed.test.ts + the positional call-site updates.
- client: the feed = {...} SDK accessor and its feed response type imports.

Kept: data/feed.zod trimmed to FeedItemType / FeedFilterMode (live UI config
for the record activity component). Regenerated api-surface.json,
json-schema.manifest.json, and content/docs/references. The residual
discovery/dispatcher feed capability surface is tracked as a follow-up (#3180).


Claude-Session: https://claude.ai/code/session_01HtN5uPoPnFzkSJ2HcwzgtG

Co-authored-by: Claude <noreply@anthropic.com>

Author: os-zhuang

.changeset/retire-feed-contracts.md

@@ -0,0 +1,53 @@
+---
+"@objectstack/spec": minor
+"@objectstack/metadata-protocol": minor
+"@objectstack/client": minor
+"@objectstack/objectql": patch
+---
+
+**Breaking (npm type surface): retire the vestigial feed contracts + protocol surface (ADR-0052 §5 follow-up, #1959).**
+
+The `service-feed` runtime was deleted in #1955; `sys_comment` / `sys_activity`
+are the canonical record-collaboration/timeline backend. This removes the dead
+type surface that still pointed at the deleted runtime — every removed method was
+already unreachable (the feed REST route was never mounted → 404; the protocol
+implementation was never wired with a feed service, so `requireFeedService()`
+could only throw). No behavior changes.
+
+No authorable metadata key is removed (the `feeds:` object capability flag and
+the `RecordActivity` UI component config are unchanged), so `PROTOCOL_MAJOR`
+stays 15 and this ships as `minor` rather than a protocol major.
+
+FROM → TO migration for every removed export:
+
+- `@objectstack/spec/contracts` — `IFeedService`, `CreateFeedItemInput`,
+  `UpdateFeedItemInput`, `ListFeedOptions`, `FeedListResult` → **removed, no
+  replacement**. Comments/activity are plain records: write `sys_comment` / read
+  `sys_activity` via the data engine or the REST data API.
+- `@objectstack/spec/api` — `FeedApiContracts`, `FeedApiErrorCode`,
+  `FeedProtocol`, and all feed request/response schemas + types (`GetFeed*`,
+  `CreateFeedItem*`, `UpdateFeedItem*`, `DeleteFeedItem*`, `AddReaction*`,
+  `RemoveReaction*`, `PinFeedItem*`, `UnpinFeedItem*`, `StarFeedItem*`,
+  `UnstarFeedItem*`, `SearchFeed*`, `GetChangelog*`, `ChangelogEntry`,
+  `SubscribeRequest/Response`, `FeedUnsubscribeRequest`, `UnsubscribeResponse`,
+  `FeedPathParams`, `FeedItemPathParams`, `FeedListFilterType`) → **removed**. Use
+  the data API against `sys_comment` / `sys_activity` (`/api/v1/data/sys_comment/…`);
+  reactions and threaded replies are fields on `sys_comment`.
+- `@objectstack/spec/data` — `FeedItemSchema`/`FeedItem`, `FeedActorSchema`/`FeedActor`,
+  `MentionSchema`/`Mention`, `ReactionSchema`/`Reaction`,
+  `FieldChangeEntrySchema`/`FieldChangeEntry`, `FeedVisibility`,
+  `RecordSubscriptionSchema`/`RecordSubscription`, `SubscriptionEventType`, and the
+  `data`-namespace `NotificationChannel` → **removed**. `FeedItemType` and
+  `FeedFilterMode` are **kept** (live UI activity-timeline config). For notification
+  channels use `NotificationChannelSchema` from `@objectstack/spec/system`.
+- `@objectstack/client` — `client.feed.*` (`list` / `create` / `update` / `delete` /
+  `addReaction` / `removeReaction` / `pin` / `unpin` / `star` / `unstar` / `search` /
+  `getChangelog` / `subscribe` / `unsubscribe`) and the re-exported feed response
+  types → **removed**. One-line fix: use `client.data.*` on `sys_comment` /
+  `sys_activity`, e.g. `client.data.create('sys_comment', { object, record_id, body })`
+  and `client.data.find('sys_activity', { filters: [['record_id', '=', id]] })`.
+- `@objectstack/metadata-protocol` — `ObjectStackProtocolImplementation` no longer
+  implements the 14 feed methods; its constructor
+  `(engine, getServicesRegistry?, getFeedService?, environmentId?)` becomes
+  `(engine, getServicesRegistry?, environmentId?)`. One-line fix: delete the third
+  argument.