---
phase: 02-backend-refactor
verified: 2026-03-24T08:41:00Z
status: passed
score: 9/9 must-haves verified
re_verification: false
---

# Phase 2: Backend Refactor Verification Report

**Phase Goal:** The codebase has a clean Store interface and Server struct so the SQLite implementation can be swapped without touching HTTP handlers, enabling parallel test execution and PostgreSQL support
**Verified:** 2026-03-24T08:41:00Z
**Status:** passed
**Re-verification:** No — initial verification

## Goal Achievement

### Observable Truths

| # | Truth | Status | Evidence |
|---|-------|--------|----------|
| 1 | All existing tests pass with zero behavior change after the refactor | VERIFIED | `go test ./pkg/diunwebhook/` — 34 tests, 34 PASS, 0 FAIL, 0.046s |
| 2 | HTTP handlers contain no SQL — all persistence goes through named Store methods | VERIFIED | `diunwebhook.go` contains 9 `s.store.X()` calls; grep for `db.Exec`, `db.Query`, `db.QueryRow` in handlers returns empty |
| 3 | Package-level global variables (db, mu, webhookSecret) no longer exist | VERIFIED | grep for `var db`, `var mu`, `var webhookSecret` in `diunwebhook.go` returns empty |
| 4 | Schema changes are applied via versioned migration files, not ad-hoc DDL in application code | VERIFIED | `migrate.go` uses golang-migrate + embed.FS; `0001_initial_schema.up.sql` contains full schema DDL; `InitDB` function removed |
| 5 | Store interface defines all 9 persistence operations with no SQL in the contract | VERIFIED | `store.go` exports `Store` interface with exactly: UpsertEvent, GetUpdates, AcknowledgeUpdate, ListTags, CreateTag, DeleteTag, AssignTag, UnassignTag, TagExists |
| 6 | SQLiteStore implements every Store method using raw SQL and a sync.Mutex | VERIFIED | `sqlite_store.go` contains all 9 method implementations with mutex guards on write operations |
| 7 | RunMigrations applies embedded SQL files via golang-migrate and tolerates ErrNoChange | VERIFIED | `migrate.go` line 32: `!errors.Is(err, migrate.ErrNoChange)` guard present; uses `iofs.New` + `sqlitemigrate.WithInstance` |
| 8 | main.go constructs SQLiteStore, runs migrations, builds Server, and registers routes | VERIFIED | `main.go` chain: `sql.Open` → `diun.RunMigrations(db)` → `diun.NewSQLiteStore(db)` → `diun.NewServer(store, secret)` → `srv.WebhookHandler` etc. |
| 9 | Each test gets its own in-memory database via NewTestServer (no shared global state) | VERIFIED | `export_test.go` exports `NewTestServer()` and `NewTestServerWithSecret()`; every test function calls one of these; `diun.UpdatesReset()` and `func TestMain` are absent from test file |

**Score:** 9/9 truths verified

### Required Artifacts

| Artifact | Expected | Status | Details |
|----------|----------|--------|---------|
| `pkg/diunwebhook/store.go` | Store interface with 9 methods | VERIFIED | 15 lines; exports `Store` with all 9 method signatures; no SQL, no `*sql.DB` in contract |
| `pkg/diunwebhook/sqlite_store.go` | SQLiteStore struct implementing Store | VERIFIED | 184 lines; `SQLiteStore` struct; `NewSQLiteStore` sets `MaxOpenConns(1)` and `PRAGMA foreign_keys = ON`; all 9 methods implemented with correct SQL and mutex |
| `pkg/diunwebhook/migrate.go` | RunMigrations function using golang-migrate + embed.FS | VERIFIED | 37 lines; `//go:embed migrations/sqlite`; `RunMigrations(db *sql.DB) error`; uses `database/sqlite` (not `sqlite3`, no CGO); ErrNoChange guard present |
| `pkg/diunwebhook/migrations/sqlite/0001_initial_schema.up.sql` | Baseline schema DDL | VERIFIED | Creates all 3 tables with `CREATE TABLE IF NOT EXISTS`; includes `acknowledged_at TEXT`; `ON DELETE CASCADE` on tag_assignments |
| `pkg/diunwebhook/migrations/sqlite/0001_initial_schema.down.sql` | Rollback DDL | VERIFIED | `DROP TABLE IF EXISTS` for all 3 tables in dependency order |
| `pkg/diunwebhook/diunwebhook.go` | Server struct with handler methods | VERIFIED | Contains `Server` struct, `NewServer`, and all 6 handler methods as `(s *Server)` receivers; no package-level globals; no SQL |
| `pkg/diunwebhook/export_test.go` | NewTestServer helper for tests | VERIFIED | Exports `NewTestServer()`, `NewTestServerWithSecret()`, `TestUpsertEvent()`, `TestGetUpdates()`, `TestGetUpdatesMap()` |
| `cmd/diunwebhook/main.go` | Wiring: sql.Open -> RunMigrations -> NewSQLiteStore -> NewServer -> route registration | VERIFIED | Full wiring chain present; `srv.WebhookHandler` method references (not package functions) |

### Key Link Verification

| From | To | Via | Status | Details |
|------|----|-----|--------|---------|
| `pkg/diunwebhook/diunwebhook.go` | `pkg/diunwebhook/store.go` | `Server.store` field of type `Store` | VERIFIED | `s.store.UpsertEvent`, `s.store.GetUpdates`, `s.store.AcknowledgeUpdate`, `s.store.ListTags`, `s.store.CreateTag`, `s.store.DeleteTag`, `s.store.TagExists`, `s.store.AssignTag`, `s.store.UnassignTag` — 9 distinct call sites confirmed |
| `cmd/diunwebhook/main.go` | `pkg/diunwebhook/sqlite_store.go` | `diun.NewSQLiteStore(db)` | VERIFIED | Line 33 of main.go |
| `cmd/diunwebhook/main.go` | `pkg/diunwebhook/migrate.go` | `diun.RunMigrations(db)` | VERIFIED | Line 29 of main.go |
| `pkg/diunwebhook/diunwebhook_test.go` | `pkg/diunwebhook/export_test.go` | `diun.NewTestServer()` | VERIFIED | 14+ call sites in test file; `NewTestServerWithSecret` used for auth tests |
| `pkg/diunwebhook/sqlite_store.go` | `pkg/diunwebhook/store.go` | interface implementation | VERIFIED | All 9 `func (s *SQLiteStore)` method signatures match `Store` interface; `go build ./pkg/diunwebhook/` exits 0 |
| `pkg/diunwebhook/migrate.go` | `pkg/diunwebhook/migrations/sqlite/` | `//go:embed migrations/sqlite` | VERIFIED | Embed directive present on line 14 of migrate.go; both migration files present in directory |

### Data-Flow Trace (Level 4)

Not applicable. This phase refactors infrastructure — no UI components or data-rendering artifacts were introduced. All artifacts are Go packages (storage layer, HTTP handlers, migration runner). Data flow correctness is validated by the test suite (34 tests, all passing).

### Behavioral Spot-Checks

| Behavior | Command | Result | Status |
|----------|---------|--------|--------|
| All 34 tests pass | `go test -v -count=1 ./pkg/diunwebhook/` | 34 PASS, 0 FAIL, ok 0.046s | PASS |
| Binary compiles | `go build ./cmd/diunwebhook/` | exits 0 | PASS |
| go vet passes | `go vet ./...` | exits 0 | PASS |
| Module exports expected functions | `store.go` contains `Store` interface | confirmed | PASS |
| No CGO sqlite dependency | grep `mattn/go-sqlite3` in go.mod | absent (mattn/go-isatty is an unrelated terminal-detection indirect dep) | PASS |

### Requirements Coverage

| Requirement | Source Plan | Description | Status | Evidence |
|-------------|-------------|-------------|--------|----------|
| REFAC-01 | 02-01, 02-02 | Database operations are behind a Store interface with separate SQLite and PostgreSQL implementations | SATISFIED (partial note below) | `store.go` defines Store interface; `sqlite_store.go` implements it; PostgreSQL implementation is Phase 3 scope per ROADMAP — Phase 2 goal says "enabling PostgreSQL support" (future), not implementing it |
| REFAC-02 | 02-02 | Package-level global state (db, mu, webhookSecret) is replaced with a Server struct that holds dependencies | SATISFIED | `diunwebhook.go` contains `Server` struct with `store Store` and `webhookSecret string` fields; package-level globals absent |
| REFAC-03 | 02-01 | Schema migrations use golang-migrate with separate migration directories per dialect (sqlite/, postgres/) | SATISFIED (partial note below) | `migrations/sqlite/` directory with versioned files exists; `postgres/` directory not yet created — deferred to Phase 3 per ROADMAP, consistent with success criteria 4 |

**Note on "partial" items:** REFAC-01 mentions "PostgreSQL implementations" (plural) and REFAC-03 mentions `postgres/` directory. Neither is required by the four ROADMAP success criteria for Phase 2. The ROADMAP explicitly scopes PostgreSQL implementation to Phase 3. These are forward-looking requirements that this phase sets up structurally. No gap is raised.

### Anti-Patterns Found

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

Scanned all phase-modified files for TODOs, placeholder returns, hardcoded empty data, stub handlers, and empty implementations. None found. All handler methods delegate to `s.store.X()` with full error handling and correct HTTP status codes.

### Human Verification Required

No human verification required. All success criteria are verifiable programmatically and all automated checks passed.

## Summary

Phase 2 fully achieves its goal. The codebase now has:

1. A `Store` interface (9 methods) that completely decouples HTTP handlers from SQL
2. A `SQLiteStore` implementation with all persistence logic, per-connection PRAGMA setup, and mutex guards
3. A `RunMigrations` function using golang-migrate and embedded SQL files, tolerating ErrNoChange
4. A `Server` struct that receives `Store` as a dependency — no package-level globals remain
5. `main.go` wiring the full chain: `sql.Open` → `RunMigrations` → `NewSQLiteStore` → `NewServer` → routes
6. A `NewTestServer()` helper giving each test its own isolated in-memory database
7. All 34 tests passing, `go build` and `go vet` clean, no CGO dependency introduced

The codebase is structurally ready for Phase 3 (PostgreSQL support): adding a `PostgresStore` implementing `Store` and a `migrations/postgres/` directory will require zero changes to any HTTP handler.

---

_Verified: 2026-03-24T08:41:00Z_
_Verifier: Claude (gsd-verifier)_