---
phase: 12-comparison-view
verified: 2026-03-17T00:00:00Z
status: passed
score: 7/7 must-haves verified
re_verification: false
---

# Phase 12: Comparison View Verification Report

**Phase Goal:** Users can view all candidates for a thread side-by-side in a table with relative weight and price deltas
**Verified:** 2026-03-17
**Status:** passed
**Re-verification:** No — initial verification

## Goal Achievement

### Observable Truths

| # | Truth | Status | Evidence |
|---|-------|--------|----------|
| 1 | User can toggle to a Compare view when a thread has 2+ candidates | VERIFIED | `$threadId.tsx:172` — compare button wrapped in `{thread.candidates.length >= 2 && (...)}`; clicking calls `setCandidateViewMode("compare")` |
| 2 | Comparison table shows all candidates side-by-side with weight, price, images, notes, links, status, pros, and cons | VERIFIED | `ComparisonTable.tsx:104-269` — ATTRIBUTE_ROWS array defines all 10 rows: Image, Name, Rank, Weight, Price, Status, Link, Notes, Pros, Cons |
| 3 | The lightest candidate weight cell has a blue highlight; the cheapest candidate price cell has a green highlight | VERIFIED | `ComparisonTable.tsx:167` — `cellClass` returns `"bg-blue-50"` when `c.id === bestWeightId`; `ComparisonTable.tsx:193` — `"bg-green-50"` when `c.id === bestPriceId` |
| 4 | Non-best cells show a gray +delta string; best cells show no delta | VERIFIED | `ComparisonTable.tsx:64-66` — delta stored as `null` when `delta === 0` (best), else `+${formatWeight(delta, unit)}`; `ComparisonTable.tsx:160-162` — delta div only rendered when `!isBest && delta` |
| 5 | The table scrolls horizontally on narrow viewports while the attribute label column stays fixed on the left | VERIFIED | `ComparisonTable.tsx:274` — outer `<div className="overflow-x-auto ...">` for scroll; `ComparisonTable.tsx:282,311` — every label cell has `sticky left-0 z-10 bg-white` |
| 6 | Missing weight or price data displays a dash, never a misleading zero | VERIFIED | `ComparisonTable.tsx:152-153` — `if (c.weightGrams == null) return <span className="text-gray-300">—</span>`; `ComparisonTable.tsx:178-179` — same pattern for price |
| 7 | A resolved thread shows the comparison read-only with the winner column visually marked (amber tint + trophy) | VERIFIED | `ComparisonTable.tsx:284-301` — winner `<th>` gets `bg-amber-50 text-amber-800` + trophy icon; body cells get `bg-amber-50/50` tint via default `extraClass` branch at line 318-320; no mutation controls exist inside ComparisonTable |

**Score:** 7/7 truths verified

### Required Artifacts

| Artifact | Expected | Status | Details |
|----------|----------|--------|---------|
| `src/client/components/ComparisonTable.tsx` | Tabular side-by-side comparison component; min 120 lines | VERIFIED | 336 lines; full ATTRIBUTE_ROWS declarative pattern, useMemo deltas, sticky column, winner highlighting |
| `src/client/stores/uiStore.ts` | Extended candidateViewMode union including "compare" | VERIFIED | Line 53: `candidateViewMode: "list" \| "grid" \| "compare"` and line 54: `setCandidateViewMode: (mode: "list" \| "grid" \| "compare") => void` |
| `src/client/routes/threads/$threadId.tsx` | Compare toggle button and ComparisonTable rendering branch | VERIFIED | Line 6 imports ComparisonTable; line 172-185 conditionally renders compare button; line 207-211 renders `<ComparisonTable>` when `candidateViewMode === "compare"` |

### Key Link Verification

| From | To | Via | Status | Details |
|------|----|-----|--------|---------|
| `$threadId.tsx` | `ComparisonTable.tsx` | import + conditional render when `candidateViewMode === "compare"` | WIRED | Line 6 imports; line 207 `candidateViewMode === "compare"` branch renders `<ComparisonTable candidates={displayItems} resolvedCandidateId={thread.resolvedCandidateId} />` |
| `ComparisonTable.tsx` | `lib/formatters.ts` | `formatWeight` and `formatPrice` for cell values and delta strings | WIRED | Line 4 imports both; used at lines 66, 92, 158, 184 for both display values and delta string construction |
| `ComparisonTable.tsx` | `CandidateListItem.tsx` | `RankBadge` import for rank row | WIRED | Line 7 imports `RankBadge`; used at line 144 in the rank ATTRIBUTE_ROW render function |
| `$threadId.tsx` | `uiStore.ts` | `candidateViewMode` state read and `setCandidateViewMode` action | WIRED | Lines 24-25 read both from `useUIStore`; `candidateViewMode` read at lines 124, 152, 164, 177, 207, 212; `setCandidateViewMode` called at lines 150, 163, 175 |

### Requirements Coverage

| Requirement | Source Plan | Description | Status | Evidence |
|-------------|-------------|-------------|--------|----------|
| COMP-01 | 12-01-PLAN.md | User can view candidates side-by-side in a tabular comparison layout (weight, price, images, notes, links, status) | SATISFIED | ComparisonTable renders all fields as columns; toggle wired in $threadId.tsx |
| COMP-02 | 12-01-PLAN.md | User can see relative deltas highlighting the lightest and cheapest candidate with +/- differences | SATISFIED | useMemo delta computation at lines 47-102; blue-50/green-50 highlights; gray delta text for non-best cells |
| COMP-03 | 12-01-PLAN.md | Comparison table scrolls horizontally with a sticky label column on narrow viewports | SATISFIED | `overflow-x-auto` on wrapper; `sticky left-0 z-10 bg-white` on all label cells; `minWidth` computed from candidate count |
| COMP-04 | 12-01-PLAN.md | Comparison view displays read-only summary for resolved threads | SATISFIED | No mutation actions in ComparisonTable; winner column amber-marked with trophy; `resolvedCandidateId` prop drives the read-only winner state |

No orphaned requirements found. REQUIREMENTS.md maps COMP-01 through COMP-04 exclusively to Phase 12, all are accounted for by plan 12-01.

### Anti-Patterns Found

| File | Line | Pattern | Severity | Impact |
|------|------|---------|----------|--------|
| — | — | None found | — | — |

No TODO/FIXME/placeholder comments, empty implementations, or stub returns found in any of the three phase 12 files. Biome lint passes cleanly on all three files (only pre-existing unrelated issues in other src files; none in phase 12 files).

### Human Verification Required

#### 1. Horizontal scroll with sticky label column

**Test:** Open a thread with 3+ candidates on a narrow viewport (< 600px). Scroll the table right.
**Expected:** Candidate columns scroll off-screen left; the attribute label column (Image, Name, Rank, etc.) remains fixed at the left edge without content bleed-through.
**Why human:** CSS `sticky` behavior with `overflow-x-auto` interactions cannot be asserted by grep; only visual browser confirmation validates the `bg-white` bleed-through prevention.

#### 2. Winner column amber tint + trophy on resolved thread

**Test:** Navigate to a thread that has been resolved. Switch to compare view.
**Expected:** The winning candidate's column header shows a trophy icon and amber background; every row of that column has a subtle amber-50/50 tint. Weight/price highlight colors (blue/green) take priority over amber when the winner is also the lightest/cheapest.
**Why human:** Color layering and opacity compositing require visual verification.

#### 3. Delta display with mixed null/non-null data

**Test:** Add two candidates to a thread where one has weight data and the other does not. Switch to compare view.
**Expected:** The candidate with no weight shows an em dash in the weight row (not 0g). The one with weight shows its value with no delta label (it is trivially the best). No misleading zero appears.
**Why human:** Edge-case rendering for the null path requires runtime React state to confirm the `formatWeight(null)` → `"--"` path is reached and displayed as `—` (em dash span), not the `"--"` string fallback from formatters.

### Gaps Summary

No gaps found. All seven observable truths are verified, all three artifacts exist and are substantive, all four key links are wired end-to-end, all four COMP requirements are satisfied by traceable code, lint passes on all phase files, and 135 tests pass with zero regressions.

---

_Verified: 2026-03-17_
_Verifier: Claude (gsd-verifier)_
