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

Feed Tabs — Architect Review

By architect.

Task and commits reviewed

• Task: feed-tabs (refactorer handoff merge_and_process refactorer 4b8b4ed499, delivered as a one-item BATCH).
• Merged swarmforge-refactorer (fast-forward from de3f1c8). Commits:
  • f3a41de Specify merged posts feed with Recent/Following tabs (specifier)
  • d1372da Merge Following feed into the posts page as Recent/Following tabs (coder)
  • 4b8b4ed Refactor feed tabs: simplify mode loading, add feed-tabs properties (refactorer)
• Architect review commit: e4bda31256 (view/controller encapsulation + test consolidation + tool-written mutation and acceptance manifests).
• Verification record git_sha: e4bda31256 (client).
• Records/summary commit: this commit.

The feature merges the old /posts/following route into /posts/recent as a row of two mode buttons. On first open the page asks GET /follow/following/:addr; if the viewer follows at least one account it selects Following, otherwise Recent. Switching tabs resets to the first page. The /posts/following route and navbar item are removed. The new FeedTabsPage service composes the existing RecentFeedPage and FollowingFeedPage controllers behind injected memoDb/wallet, and the React shell (components/app-body/posts/index.js) renders it. Client-only read feature; no DB or indexer change.

Architectural review

• UI/Core separation (good). FeedTabsPage is pure coordinator logic in src/services/ with memoDb and wallet injected; it opens no network, DOM, or wallet IO itself. The React shell constructs MemoDb and the controller and maps the snapshot into view state. Acceptance drives the controller directly through the fake memo-db, so core behavior is tested with no UI or IO.
• Dependency rule (good). The view depends on the service; the service depends on the two page controllers and on the MemoDb adapter through its constructor. No high-level module reaches around the injected adapter, and the adapter does not reach back into the controller.
• Information hiding (one fix). The controller exposes a tested getState() snapshot, but the view was still reading page.posts, page.pagination, page.mode, page.emptyBecauseNoFollows, and page.offset directly. Routed showPage through getState() so the controller is the single source of feed state (see Fixes).
• Local code quality (one fix). The two default-mode unit tests were structurally identical and DRY reported them (score 1.00). Consolidated into a table-driven pair with a shared assertion helper. Added initial-state tests to kill mutation survivors the refactorer left (see Fixes).
• Delegation, not duplication (accepted). FeedTabsPage owns paging (nextPage/previousPage/canLoadMore) and delegates post loading to the two sub-pages. It computes emptyBecauseNoFollows itself from hasFollows, which is the correct merged-page semantics (the message shows only when the viewer follows no one). FollowingFeedPage still exposes its own emptyBecauseNoFollows, but that is the older /posts/following contract and is now unused by the tabs flow; it is retained only because specs/following-feed.feature still specifies it. Not changed here (specifier owns retiring that feature); noting it as the one remaining conceptual overlap.
• Module boundaries (good). The deleted following-feed component left no dangling imports; FollowingFeedPage remains as the internal delegate used by FeedTabsPage, and memo-db.js gained a thin getFollowing adapter method next to the existing getFollowingFeed.

Fixes applied

• View consumes the controller snapshot. posts/index.js showPage now reads page.getState() instead of five internal fields, keeping the controller's representation hidden behind its public accessor. The injected memoDb (needed for author-profile lookup) is still passed explicitly.
• Killed four mutation survivors with initial-state tests. The refactorer's first mutation run left constructor.offset = 0, constructor.hasFollows = false, constructor.emptyBecauseNoFollows = false, and the canLoadMore() ?? false default surviving because no test observed an unloaded controller. Added constructor starts in a neutral, unloaded state and canLoadMore is false before any page has been loaded. Final mutation: 22 killed, 0 survived, 0 uncovered.
• Removed a local test duplicate. Extracted assertOnlySelectedFeedLoaded and folded the two default-mode tests into one table so DRY reports no candidate.

No production behavior changes were needed. The controller structure, injected dependencies, and boundaries were accepted.

Verification results

Record (pinned to the review commit e4bda31256):

File	Component
docs/reviews/feed-tabs-verification.json	psf-memo-client

• Language mutation (mutate-file.sh src/services/feed-tabs-page.js --max-workers 8, run twice: the differential pass selected 0 changed sites, so the wrapper auto-reran with --mutate-all): 22 killed, 0 survived, 0 uncovered (22 total/covered, 0 uncovered).
• DRY (dry4javascript, scoped to the changed production files and the changed unit/property tests): no duplicate candidates found. The first run flagged one local duplicate in the unit test file (two default-mode tests, score 1.00); removing it cleared the report. A broad whole-client DRY run was not needed and, per standing precedent, its pre-existing step-handler and test-setup boilerplate is not part of this task.
• Cyclomatic complexity / CRAP (crap4javascript src/services/feed-tabs-page.js): maximum CRAP 5.0 at 100% coverage (open CC 5); _isEmptyFollowing/_loadMode/_normalizeTab CC 3; every other function CC ≤ 2. All functions are below the 6.0 target.
• Soft Gherkin acceptance mutation (gherkin-mutator --level soft --workers 8), psf-memo-client/specs/feed-tabs.feature: 42 total, 0 killed, 42 survived, 0 errors. Every survivor is an intrinsic equivalent: a single-character case/character substitution of an example value (followed_text, followed_txid, followee, other, other_text, other_txid) used consistently on both the setup and assertion sides of its scenario, so the scenario still passes. This is the documented behavior for this read-only feature; no implementation gap is implied. gherkin-mutator wrote an acceptance-mutation-manifest with "scenarios":[] (each scenario has an equivalent survivor, so none is recorded) and no # mutation-stamp; committed as tool-written.

Suite status

verify.sh client result: pass at git_sha e4bda31256:

• unit: 506 pass / 0 fail
• property: 121 pass / 0 fail
• acceptance: all 37 generated suites passed
• lint: ok
• build: ok

Handoffs

• End-of-chain git_handoff to specifier (priority 50) to merge swarmforge-architect into master, using this records/summary commit.
• git_handoff to coder and refactorer (priority 00) with the review commit e4bda31256 for follow-up review: the view now consumes getState(), and the default-mode tests were consolidated with added initial-state coverage; the rest is tool-written mutation and acceptance manifests.