docs: create milestone v2.1 roadmap (3 phases)

.planning/ROADMAP.md

@@ -7,6 +7,7 @@
 - ✅ **v1.2 Collection Power-Ups** — Phases 7-9 (shipped 2026-03-16)
 - ✅ **v1.3 Research & Decision Tools** — Phases 10-13 (shipped 2026-04-08)
 - ✅ **v2.0 Platform Foundation** — Phases 14-23 (shipped 2026-04-08)
+- 🚧 **v2.1 Public Discovery** — Phases 24-26 (in progress)
 
 ## Phases
 
@@ -63,6 +64,54 @@
 
 </details>
 
+### 🚧 v2.1 Public Discovery (In Progress)
+
+**Milestone Goal:** Transform GearBox from a login-first tool into a public-first discovery platform with always-on catalog search and a browsable feed of community content.
+
+- [ ] **Phase 24: Public Access & Infrastructure** - Remove the login wall from read-only routes and add rate limiting to public endpoints
+- [ ] **Phase 25: Catalog Enrichment & Agent Tools** - Add attribution fields to global items, bulk import API, and MCP tools for agent-powered seeding
+- [ ] **Phase 26: Discovery Landing Page** - Replace the dashboard with a public-first landing page featuring catalog search and community feed
+
+## Phase Details
+
+### Phase 24: Public Access & Infrastructure
+**Goal**: Anyone can browse the catalog, public setups, and user profiles without logging in
+**Depends on**: Phase 23 (v2.0 complete)
+**Requirements**: PUBL-01, PUBL-02, PUBL-03, PUBL-04, PUBL-05, INFR-01
+**Success Criteria** (what must be TRUE):
+  1. Visiting the app without a session shows the app content immediately — no auth spinner, no redirect to login
+  2. An unauthenticated visitor can browse the global item catalog and open a catalog detail page
+  3. An unauthenticated visitor can view a public setup and see its items and totals
+  4. An unauthenticated visitor can view a user's public profile page
+  5. Attempting to create, edit, or delete any item/setup/thread while unauthenticated redirects to login
+**Plans**: TBD
+**UI hint**: yes
+
+### Phase 25: Catalog Enrichment & Agent Tools
+**Goal**: Global items carry attribution metadata and can be bulk-populated by an MCP agent swarm
+**Depends on**: Phase 24
+**Requirements**: CATL-01, CATL-02, CATL-03, CATL-04, CATL-05, SEED-01, SEED-02, SEED-03
+**Success Criteria** (what must be TRUE):
+  1. A catalog item detail page displays image credit and a link to the image source
+  2. Attempting to import two items with the same brand and model updates the existing record rather than creating a duplicate
+  3. A single API call with an array of items imports them all, upserting on (brand, model) conflict
+  4. An MCP agent can call `upsert_catalog_item` with attribution fields and the item appears in the catalog
+  5. An MCP agent can call `bulk_upsert_catalog` with a batch of items and all are persisted with attribution
+**Plans**: TBD
+
+### Phase 26: Discovery Landing Page
+**Goal**: The app opens to a public discovery feed with prominent catalog search, not a personal dashboard
+**Depends on**: Phase 25
+**Requirements**: DISC-01, DISC-02, DISC-03, DISC-04, DISC-05, INFR-02
+**Success Criteria** (what must be TRUE):
+  1. The root URL shows a landing page with a catalog search bar at the top, visible without logging in
+  2. Below the search bar, a feed of popular public setups is visible with titles, creator names, and item counts
+  3. The landing page shows a section of recently added catalog items
+  4. The landing page shows a section of trending categories
+  5. A logged-in user sees a "Go to Collection" link or button on the landing page that navigates to their personal collection
+**Plans**: TBD
+**UI hint**: yes
+
 ## Progress
 
 | Phase | Milestone | Plans Complete | Status | Completed |
@@ -90,6 +139,9 @@
 | 21. Item & Catalog Detail Pages | v2.0 | 3/3 | Complete | 2026-04-06 |
 | 22. Add-from-Catalog & Thread Integration | v2.0 | 2/2 | Complete | 2026-04-06 |
 | 23. Manual Entry Fallback | v2.0 | 1/1 | Complete | 2026-04-06 |
+| 24. Public Access & Infrastructure | v2.1 | 0/TBD | Not started | - |
+| 25. Catalog Enrichment & Agent Tools | v2.1 | 0/TBD | Not started | - |
+| 26. Discovery Landing Page | v2.1 | 0/TBD | Not started | - |
 
 ## Backlog