chore(components): remove dead user prop from MobileNavigation (#28)

components/MobileNavigation.js has accepted a `user` prop ever since
the mobile bottom-bar was extracted from Layout, but it has never read
any field of `user`. The bottom-bar items (Cards, Decks, Dashboard,
Community, More) are statically configured — none of them branch on
auth state, role, user id, or any other per-user attribute. The prop
is dead.

This was originally surfaced as R8 in the fix-layout-default-user
convoy (commit ca302a8) and deliberately deferred there to keep that
convoy focused on the Layout default-user fix. The follow-up was
queued as cleanup-mobile-nav-dead-props in .convoys/ship-readiness.md
§ Queued convoys. Pre-edit audit confirms the queue entry's premise:
`rg '\\buser\\b' components/MobileNavigation.js` returns 1 hit (the
destructure on line 5) before the change and 0 hits after. The
only active call site is components/Layout.js line 598; the
components/Layout.js.backup snapshot also calls it but is a
no-go-zone (per .cursor/rules/no-go-zones.mdc § "Append-only /
historical") and stays untouched — when that backup is eventually
deleted in a separate convoy, its stale call disappears with it.

Verification: npm run lint exit 1 with 128 problems (baseline
preserved, no regression introduced); npm run test:run 21/21 pass
(test/components/Layout.test.js still asserts the logged-out branch
contract from PR #15 — the dead-prop removal is invisible to that
suite since it does not inspect MobileNavigation's prop shape).
Convoy file .convoys/cleanup-mobile-nav-dead-props.md captures the
audit, fix, risks (R1: a future per-user bottom-bar feature would
need to re-add the prop — accepted; carrying dead state to hedge
hypothetical features is worse than paying the one-line re-add cost
when the feature actually lands), and acceptance criteria.

Co-authored-by: Cursor <cursoragent@cursor.com>

.convoys/cleanup-mobile-nav-dead-props.md

@@ -0,0 +1,155 @@
+# cleanup-mobile-nav-dead-props (P3 polish — single-prop hygiene)
+
+**Status:** SHIPPED 2026-05-26 (PR TBD)
+**Classification:** hygiene
+**Priority:** P3 polish (not a bug, not a security issue; dead-prop
+removal is purely a clarity-of-surface cleanup)
+**Convoy owner:** parent (no architect — single-line prop removal in
+one component + one caller; surfaced and pre-decided in a sibling
+convoy)
+**Opened:** 2026-05-26
+
+## Background
+
+`components/MobileNavigation.js` accepts `{ user, onMenuOpen }` but
+never reads `user.*` — the bottom-bar items (Cards, Decks, Dashboard,
+Community, More) are static and don't depend on auth state or role.
+
+This was originally surfaced as **R8** in the `fix-layout-default-user`
+convoy (see `.convoys/fix-layout-default-user.md` § R8 and § "Anything
+flagged but not acted on") and deferred there with explicit
+instructions: *"If the implementer is tempted to delete the prop, they
+MUST stop — that's god-component-split / single-auth-provider
+territory."* The deferral was correct for that convoy's scope; it is
+no longer needed because the prop is genuinely dead at the current
+static-bar reality, and removing it does not require a wider auth
+refactor.
+
+The follow-up was queued as `cleanup-mobile-nav-dead-props` in
+`.convoys/ship-readiness.md` § Queued convoys, with a note that it
+may fold into `god-component-split` (P2 #13) if that lands first.
+God-component-split has not landed; this small hygiene convoy ships
+first.
+
+## Audit results
+
+Pre-edit audit (the spec's "don't blindly trust the queue entry"
+clause):
+
+1. **Reading `components/MobileNavigation.js`** — the file is 171
+   lines. Line 5 destructures `{ user, onMenuOpen }`. Lines 6–170 use
+   `onMenuOpen` exactly once (line 39, as the `onClick` for the "More"
+   button). `user` does not appear elsewhere — no `user.email`,
+   `user.role`, `user.id`, no conditional render gated on `user`, no
+   pass-through to a child component. The bottom-bar `navigationItems`
+   array is hardcoded and does not branch on auth state.
+2. **`rg '\buser\b' components/MobileNavigation.js`** before edit: 1
+   hit (the destructure on line 5). After edit: 0 hits.
+3. **`rg "MobileNavigation" components/ pages/ --type js`**: two
+   import + JSX-callsite pairs in the codebase:
+   - `components/Layout.js` (active) — line 5 import, line 598-601 JSX
+     call passing `user={user}` and `onMenuOpen={...}`.
+   - `components/Layout.js.backup` (no-go-zone per
+     `.cursor/rules/no-go-zones.mdc` § "Append-only / historical" —
+     "legacy snapshot; delete with a real PR, never edit") — line 5
+     import, line 264 JSX call. Left untouched per the no-go-zone
+     rule; if/when the `.backup` file is eventually deleted, this dead
+     call disappears with it.
+
+Audit verdict: `user` is genuinely dead. Cleanup is safe.
+
+## The fix
+
+Two-file, three-line diff:
+
+1. **`components/MobileNavigation.js` line 5**: remove `user` from the
+   destructured props.
+   - Before: `export default function MobileNavigation({ user, onMenuOpen }) {`
+   - After:  `export default function MobileNavigation({ onMenuOpen }) {`
+2. **`components/Layout.js` lines 598-601**: remove the `user={user}`
+   JSX attribute from the only active call site.
+   - Before:
+     ```
+     <MobileNavigation
+       user={user}
+       onMenuOpen={() => setIsMobileMenuOpen(true)}
+     />
+     ```
+   - After:
+     ```
+     <MobileNavigation
+       onMenuOpen={() => setIsMobileMenuOpen(true)}
+     />
+     ```
+
+No new code. No refactors. No tests added (the component has no
+direct test coverage; `test/components/Layout.test.js` tests Layout's
+logged-out branch and does not assert on `MobileNavigation`'s prop
+shape).
+
+## Out of scope
+
+- The unused `import { useState } from 'react'` on
+  `components/MobileNavigation.js` line 3. The hook is imported but
+  not called. This is a pre-existing dead import unrelated to the
+  `user` prop; the convoy spec explicitly forbids "refactor anything
+  else in MobileNavigation.js (this is a single-prop removal)". A
+  future hygiene pass can sweep it (or it'll get caught by an
+  eventual lint-no-unused-imports rule).
+- `components/Layout.js.backup` — no-go-zone, untouched.
+
+## Verification plan
+
+1. `rg '\buser\b' components/MobileNavigation.js` → 0 hits (post-edit
+   confirmation that the prop is truly gone, not just renamed).
+2. `rg "MobileNavigation" components/ pages/ --type js` → confirm
+   each active call site passes only `onMenuOpen`.
+3. `npm run lint` → 128 problems baseline preserved (no regression
+   introduced; no new dead-code/unused-var warnings created by the
+   change).
+4. `npm run test:run` → 21/21 pass. Specifically,
+   `test/components/Layout.test.js` continues to pass — its
+   regression-lock assertions for the logged-out Layout branch
+   (Gotcha #8) do not depend on `MobileNavigation`'s prop shape, so
+   the dead-prop removal is invisible to that suite.
+5. `npm run build` skipped — relying on Vercel preview CI. Trade-off:
+   single-prop removal in a leaf component is extremely low risk of
+   build-time regression, and the Playwright smoke + visual-diff
+   workflows on the PR will catch any Layout-rendering issue before
+   merge.
+
+## Risks
+
+- **R1 — A future feature that wants per-user bottom-bar items would
+  need to re-add the prop.** Hypothetical examples: showing an
+  unread-count badge on a "Notifications" tab gated on `user.id`, or
+  hiding the "Community" tab for unauthenticated visitors. **Accepted.**
+  Re-adding a prop is a one-line change when the feature actually
+  lands; carrying a dead prop "just in case" obscures the current
+  surface and adds nothing. The cleanup is correct for the
+  current static-bar reality; future features pay their own
+  add-the-prop cost.
+- **R2 — `components/Layout.js.backup` still references the old prop
+  shape.** **Accepted.** The backup is a no-go-zone (per
+  `.cursor/rules/no-go-zones.mdc`) and is dead code by definition.
+  Touching it would violate the rule; leaving it as a stale snapshot
+  is the convention. When the backup is eventually deleted in a
+  separate convoy, this stale call disappears with it.
+
+## Acceptance criteria
+
+- 2 files modified, 3 lines net change (1 line edit + 1 attribute
+  removal from a multi-line JSX block).
+- `npm run lint` exit 1 with 128 problems (baseline preserved).
+- `npm run test:run` 21/21 pass.
+- `rg '\buser\b' components/MobileNavigation.js` → 0 hits post-edit.
+
+## Owns
+
+Parent (single-prop removal in a leaf component; no architect or
+implementer subagent required; audit confirms the queue entry's
+premise).
+
+## As-shipped
+
+_To be filled in post-merge._

components/Layout.js

@@ -596,7 +596,6 @@ export default function Layout({ children, user = null, showSearch = false }) {
     <div className="flex h-screen" style={{ backgroundColor: 'var(--bg-primary)' }}>
       {/* Mobile Navigation - Bottom bar for mobile */}
       <MobileNavigation 
-        user={user} 
         onMenuOpen={() => setIsMobileMenuOpen(true)} 
       />
 

components/MobileNavigation.js

@@ -2,7 +2,7 @@ import { useRouter } from 'next/router';
 import Link from 'next/link';
 import { useState } from 'react';
 
-export default function MobileNavigation({ user, onMenuOpen }) {
+export default function MobileNavigation({ onMenuOpen }) {
   const router = useRouter();
 
   // Navigation items for the bottom bar