docs: create roadmap (3 phases)

.planning/REQUIREMENTS.md

@@ -64,19 +64,19 @@ Which phases cover which requirements. Updated during roadmap creation.
 | PEOPLE-02 | Phase 1 | Pending |
 | PEOPLE-03 | Phase 1 | Pending |
 | PEOPLE-04 | Phase 1 | Pending |
-| CALC-01 | Phase 1 | Pending |
-| CALC-02 | Phase 1 | Pending |
-| CALC-03 | Phase 1 | Pending |
-| CALC-04 | Phase 1 | Pending |
-| PERSIST-01 | Phase 2 | Pending |
-| PERSIST-02 | Phase 2 | Pending |
-| PERSIST-03 | Phase 2 | Pending |
+| CALC-01 | Phase 2 | Pending |
+| CALC-02 | Phase 2 | Pending |
+| CALC-03 | Phase 2 | Pending |
+| CALC-04 | Phase 2 | Pending |
+| PERSIST-01 | Phase 3 | Pending |
+| PERSIST-02 | Phase 3 | Pending |
+| PERSIST-03 | Phase 3 | Pending |
 
 **Coverage:**
 - v1 requirements: 11 total
 - Mapped to phases: 11
-- Unmapped: 0 ✓
+- Unmapped: 0
 
 ---
 *Requirements defined: 2026-03-11*
-*Last updated: 2026-03-11 after initial definition*
+*Last updated: 2026-03-11 after roadmap creation*

.planning/ROADMAP.md

@@ -0,0 +1,71 @@
+# Roadmap: Expense Splitter
+
+## Overview
+
+Build a client-side bill splitting app that takes users from "we just ate" to "here's what everyone owes" in seconds. Start with the core data entry and assignment flow, add accurate calculations with tip handling, then enable persistence so users can reference past bills.
+
+## Phases
+
+**Phase Numbering:**
+- Integer phases (1, 2, 3): Planned milestone work
+- Decimal phases (2.1, 2.2): Urgent insertions (marked with INSERTED)
+
+Decimal phases appear between their surrounding integers in numeric order.
+
+- [ ] **Phase 1: Bill Entry & Assignment** - Add people, items, and assign who ordered what
+- [ ] **Phase 2: Calculation & Results** - See who owes what with tip calculations
+- [ ] **Phase 3: Bill History** - Save, view, and load past bills
+
+## Phase Details
+
+### Phase 1: Bill Entry & Assignment
+**Goal**: Users can create a bill by adding people and items with flexible assignments
+**Depends on**: Nothing (first phase)
+**Requirements**: PEOPLE-01, PEOPLE-02, PEOPLE-03, PEOPLE-04
+**Success Criteria** (what must be TRUE):
+  1. User can add people to the bill by entering their names
+  2. User can add items with name and price to the bill
+  3. User can assign any item to one or more specific people
+  4. User can mark an item as "shared" to split it across selected people
+**Plans**: TBD
+
+Plans:
+- [ ] 01-01: [To be defined during planning]
+
+### Phase 2: Calculation & Results
+**Goal**: Users can see exactly who owes what with tip applied
+**Depends on**: Phase 1
+**Requirements**: CALC-01, CALC-02, CALC-03, CALC-04
+**Success Criteria** (what must be TRUE):
+  1. User can see each person's subtotal from their assigned items
+  2. User can set a global tip percentage that applies to everyone
+  3. User can see each person's final total with tip included
+  4. User can view a clear summary showing who owes how much
+**Plans**: TBD
+
+Plans:
+- [ ] 02-01: [To be defined during planning]
+
+### Phase 3: Bill History
+**Goal**: Users can save and retrieve their past bills
+**Depends on**: Phase 2
+**Requirements**: PERSIST-01, PERSIST-02, PERSIST-03
+**Success Criteria** (what must be TRUE):
+  1. User's bills are automatically saved to browser local storage
+  2. User can view a list of their past bills
+  3. User can load a past bill to review the details
+**Plans**: TBD
+
+Plans:
+- [ ] 03-01: [To be defined during planning]
+
+## Progress
+
+**Execution Order:**
+Phases execute in numeric order: 1 -> 2 -> 3
+
+| Phase | Plans Complete | Status | Completed |
+|-------|----------------|--------|-----------|
+| 1. Bill Entry & Assignment | 0/TBD | Not started | - |
+| 2. Calculation & Results | 0/TBD | Not started | - |
+| 3. Bill History | 0/TBD | Not started | - |

.planning/STATE.md

@@ -0,0 +1,59 @@
+# Project State
+
+## Project Reference
+
+See: .planning/PROJECT.md (updated 2026-03-11)
+
+**Core value:** Everyone leaves knowing exactly what they owe - no arguing, no awkward math at the table.
+**Current focus:** Phase 1: Bill Entry & Assignment
+
+## Current Position
+
+Phase: 1 of 3 (Bill Entry & Assignment)
+Plan: 0 of TBD
+Status: Ready to plan
+Last activity: 2026-03-11 - Roadmap created
+
+Progress: [░░░░░░░░░░] 0%
+
+## Performance Metrics
+
+**Velocity:**
+- Total plans completed: 0
+- Average duration: -
+- Total execution time: -
+
+**By Phase:**
+
+| Phase | Plans | Total | Avg/Plan |
+|-------|-------|-------|----------|
+| - | - | - | - |
+
+**Recent Trend:**
+- Last 5 plans: -
+- Trend: -
+
+*Updated after each plan completion*
+
+## Accumulated Context
+
+### Decisions
+
+Decisions are logged in PROJECT.md Key Decisions table.
+Recent decisions affecting current work:
+
+None yet.
+
+### Pending Todos
+
+None yet.
+
+### Blockers/Concerns
+
+None yet.
+
+## Session Continuity
+
+Last session: 2026-03-11
+Stopped at: Roadmap created, ready to plan Phase 1
+Resume file: None