psf-memo/docs/reviews/following-feed-summary.md

following-feed — Architect Review Summary

By architect.

Task and commits reviewed

• Task: following-feed (refactorer handoff, merge_and_process refactorer d606ee6608)
• Merged swarmforge-refactorer (fast-forward) — commits:
  • 6d94372 Spec Following feed (P6.6) (specifier)
  • 6d1bd14 Implement Following feed (coder)
  • d606ee6 Refactor following feed: reduce CRAP/DRY, add property coverage (refactorer)

Follow-up refactorer handoff (merge_and_process refactorer b85878a5d5)

• Merged swarmforge-refactorer — commit b85878a "Refactor following-feed scan: extract isFolloweePost to cut CRAP".
• Architectural review (confirmed good): isFolloweePost is a private helper within PostQuery that extracts the reply/viewer/membership predicate from scanFollowingFeedTxidsAndCount. It adds no new dependencies, preserves information hiding (the LevelDB model stays encapsulated), and keeps the dependency direction inward. Behavior is unchanged.
• CRAP reduction confirmed: scanFollowingFeedTxidsAndCount CC 7→5 (CRAP 7.0→5.0); isFolloweePost CC 3, both 100% covered.
• Mutation: post-query.js 0 killed / 0 survived / 0 uncovered (manifest refreshed by the approved tool).
• DRY: no new production duplication; only pre-existing test-helper duplicates.
• Soft Gherkin mutation: following-feed.feature 12 executed, 0 killed, 12 survived — all genuine equivalents (single-char case mutations of example values), unchanged from the prior review.
• Suites: DB unit 281 passing, property 37 passing, acceptance 9 files passing, lint clean; client acceptance 19 files passing.

Architectural findings and fixes

• UI/Core separation (confirmed good): Client FollowingFeedPage is a thin, testable controller wrapping the MemoDb HTTP client; the React FollowingFeed component stays a pure UI shell. The feature is read-only and needs no wallet broadcast. Core behavior is testable without UI or network I/O.
• Dependency rule (confirmed good): DB ListFollowingFeed extends the shared ListUseCase base and depends only on the followQuery and postQuery adapter interfaces; the /posts REST controller is a thin adapter. The refactorer's runUseCase/listPostsForAddr extraction removed the duplicated try/catch error wrapper across the addr-scoped handlers.
• Information hiding (confirmed good): PostQuery.scanFollowingFeedTxidsAndCount encapsulates the LevelDB key/iterator model and the follows-join; the controller hides the query/limit/offset wiring; the client MemoDb.getFollowingFeed hides the HTTP endpoint. No framework or persistence structures leak across boundaries.
• DRY reductions applied (behavior-preserving): extracted parseRequiredString into src/use-cases/lib/pagination.js and used it in ListFollowingFeed, ListPostsByAddr, and ListTopicPosts, removing the three duplicated parseAddr/parseRoom required-field guards.

Test hardening applied (kill mutation survivors / cover uncovered)

• psf-memo-client following-feed-page.test.js (covered 2 previously-uncovered sites):
  • constructor starts with emptyBecauseNoFollows false — covers the constructor field init;
  • canLoadMore is false when pagination is absent — covers the canLoadMore null-guard.
• psf-memo-db use-cases/index.unit.js (new): composition-root test asserting start() instantiates every use case (including listFollowingFeed) and that the constructor rejects missing adapters — covers the previously-uncovered UseCases.start wiring.

No production behavior changed; the only non-test source diffs are tool-generated mutation manifests and the Gherkin acceptance-mutation stamp.

Verification results

Language mutation (mutate4javascript, differential vs manifest)

• psf-memo-db — all affected files 0 killed / 0 survived / 0 uncovered: list-following-feed.js, list-posts-by-addr.js, list-topic-posts.js, lib/pagination.js, use-cases/index.js, adapters/post-query.js, controllers/rest-api/posts/controller.js, controllers/rest-api/posts/index.js.
• psf-memo-client
  • following-feed-page.js 0 killed / 0 survived / 0 uncovered.
  • memo-db.js excluded: HTTP adapter using ESM + directory import (../config) only resolvable via react-scripts/webpack, not loadable under plain node --test; its read behavior is exercised end-to-end via the DB /posts/following acceptance. Consistent with the search precedent.

DRY (dry4javascript)

• The parseRequiredString extraction removed the three duplicated required-field guards.
• Remaining duplicates are pre-existing pattern-boilerplate inherent to the established layered conventions (follow/mute/poll controllers, route-registration index.js, memo-follow/memo-mute services) and test/acceptance helpers — left as-is, consistent with prior reviews.

CRAP / cyclomatic complexity (crap4javascript)

All following-feed functions well below the 8.0 threshold — highest is FollowingFeedPage.load (CC 6, 100% cov, CRAP 6.0) and parseRequiredString (CC 3, 100% cov, CRAP 3.0); the rest are CC 1–2 with 100% coverage.

Soft Gherkin acceptance mutation (gherkin-mutator --level soft)

• psf-memo-client following-feed.feature: 12 executed, 0 killed, 12 survived — all survivors are single-character case mutations of the example values (addresses, text, txids). Each example value is used consistently on both the setup and assertion sides of its scenario, so the mutation yields the same result set; the mutations are genuine equivalents. Specifier-side feature-quality item.

No implementation changes are warranted for the soft-mutation survivors; they are intrinsic equivalents.

Suite status

• psf-memo-client: unit 229 passing (was 227; +2 hardening tests), property 30 passing, acceptance 19 generated files, all passing, lint clean, build pass.
• psf-memo-db: unit 281 passing (was 280; +1 new composition-root test), property 37 passing, acceptance 9 generated files, all passing, lint clean.
• psf-memo-indexer: unit 85 passing (untouched by this task).

Handoffs sent

• git_handoff to coder and refactorer (priority: 00) with the review commit (test hardening + refreshed mutation manifests + Gherkin acceptance-mutation stamp) for follow-up review.
• No specifier handoff: no functional or spec change in this commit (only test hardening and tool-generated manifests/stamps).