docs(06-01): complete plan 01 DB safety constraints and first-run flag summary

.planning/phases/06-preset-data-first-run-detection-and-db-safety/06-01-SUMMARY.md

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+---
+phase: 06-preset-data-first-run-detection-and-db-safety
+plan: "01"
+subsystem: database
+tags: [migrations, schema, typescript, constraints, first-run]
+dependency_graph:
+  requires: []
+  provides: [uniqueness-constraints, setup_completed-column, profile-type-update]
+  affects: [profiles, budgets, categories]
+tech_stack:
+  added: []
+  patterns: [safe-deduplication-before-unique-constraint, alter-table-with-backfill]
+key_files:
+  created:
+    - supabase/migrations/006_uniqueness_constraints.sql
+    - supabase/migrations/007_setup_completed.sql
+  modified:
+    - src/lib/types.ts
+decisions:
+  - "Used wider UNION backfill in 007 (categories OR template_items) per Pitfall 3 guidance — protects v1.0 users with templates but no categories"
+  - "Migration 006 wraps deduplication DELETE and ADD CONSTRAINT in single BEGIN/COMMIT for atomicity"
+metrics:
+  duration: "4 minutes"
+  completed: "2026-04-20"
+  tasks_completed: 3
+  tasks_total: 3
+---
+
+# Phase 06 Plan 01: DB Safety Constraints and First-Run Flag Summary
+
+**One-liner:** Two atomic SQL migrations adding UNIQUE constraints on budgets/categories with safe deduplication, plus a `setup_completed` boolean on profiles with UNION backfill, synced to the TypeScript Profile interface.
+
+## Tasks Completed
+
+| Task | Name | Commit | Files |
+|------|------|--------|-------|
+| 1 | Migration 006: uniqueness constraints | 23fd3fa | supabase/migrations/006_uniqueness_constraints.sql |
+| 2 | Migration 007: setup_completed column + backfill | 0f441b6 | supabase/migrations/007_setup_completed.sql |
+| 3 | Update Profile TypeScript interface | 39840ca | src/lib/types.ts |
+
+## What Was Built
+
+**Migration 006** (`006_uniqueness_constraints.sql`): A single `BEGIN/COMMIT` transaction that:
+1. DELETEs duplicate budgets keeping the oldest per `(user_id, start_date)` using `DISTINCT ON`
+2. ADDs `CONSTRAINT budgets_user_month_unique UNIQUE (user_id, start_date)`
+3. DELETEs duplicate categories keeping the oldest per `(user_id, name)` using `DISTINCT ON`
+4. ADDs `CONSTRAINT categories_user_name_unique UNIQUE (user_id, name)`
+
+**Migration 007** (`007_setup_completed.sql`): Two statements:
+1. `ALTER TABLE profiles ADD COLUMN setup_completed boolean NOT NULL DEFAULT false`
+2. `UPDATE profiles SET setup_completed = true WHERE id IN (SELECT DISTINCT user_id FROM categories UNION SELECT t.user_id FROM templates t INNER JOIN template_items ti ON ti.template_id = t.id)`
+
+**TypeScript** (`src/lib/types.ts`): Added `setup_completed: boolean` to the `Profile` interface between `currency` and `created_at`. `tsc --noEmit` passes cleanly.
+
+## Deviations from Plan
+
+None — plan executed exactly as written. The UNION backfill in migration 007 was specified in the plan (per Pitfall 3 guidance from RESEARCH.md).
+
+## Known Stubs
+
+None — this plan produces SQL DDL and a TypeScript type update; no UI or data-flow stubs.
+
+## Threat Flags
+
+No new threat surface beyond what was documented in the plan's threat model. The UNIQUE constraints directly address T-06-01 and T-06-02. The `setup_completed` column is a UX routing flag with existing RLS (T-06-03 accepted).
+
+## Self-Check
+
+- [x] `supabase/migrations/006_uniqueness_constraints.sql` exists — FOUND
+- [x] `supabase/migrations/007_setup_completed.sql` exists — FOUND
+- [x] `src/lib/types.ts` contains `setup_completed: boolean` — FOUND (line 16)
+- [x] `tsc --noEmit` passed with no errors
+- [x] Commits 23fd3fa, 0f441b6, 39840ca exist in git log
+
+## Self-Check: PASSED