DiunDashboard/.planning/phases/03-postgresql-support/03-02-PLAN.md

---
phase: 03-postgresql-support
plan: 02
type: execute
wave: 2
depends_on: [03-01]
files_modified:
  - cmd/diunwebhook/main.go
  - pkg/diunwebhook/diunwebhook.go
  - pkg/diunwebhook/postgres_test.go
  - pkg/diunwebhook/export_test.go
  - compose.yml
  - compose.dev.yml
autonomous: true
requirements: [DB-01, DB-02, DB-03]

must_haves:
  truths:
    - "Setting DATABASE_URL starts the app using PostgreSQL; omitting it falls back to SQLite with DB_PATH"
    - "Startup log clearly indicates which backend is active"
    - "Docker Compose with --profile postgres activates a PostgreSQL service"
    - "Default docker compose (no profile) remains SQLite-only"
    - "Duplicate tag creation returns 409 on both SQLite and PostgreSQL"
  artifacts:
    - path: "cmd/diunwebhook/main.go"
      provides: "DATABASE_URL branching logic"
      contains: "DATABASE_URL"
    - path: "compose.yml"
      provides: "Production compose with postgres profile"
      contains: "profiles:"
    - path: "compose.dev.yml"
      provides: "Dev compose with postgres profile"
      contains: "profiles:"
    - path: "pkg/diunwebhook/postgres_test.go"
      provides: "Build-tagged PostgreSQL integration test helper"
      contains: "go:build postgres"
    - path: "pkg/diunwebhook/diunwebhook.go"
      provides: "Case-insensitive UNIQUE constraint detection"
      contains: "strings.ToLower"
  key_links:
    - from: "cmd/diunwebhook/main.go"
      to: "pkg/diunwebhook/postgres_store.go"
      via: "diun.NewPostgresStore(db)"
      pattern: "NewPostgresStore"
    - from: "cmd/diunwebhook/main.go"
      to: "pkg/diunwebhook/migrate.go"
      via: "diun.RunPostgresMigrations(db)"
      pattern: "RunPostgresMigrations"
    - from: "cmd/diunwebhook/main.go"
      to: "pgx/v5/stdlib"
      via: "blank import for driver registration"
      pattern: '_ "github.com/jackc/pgx/v5/stdlib"'
---

<objective>
Wire PostgresStore into the application and deployment infrastructure.

Purpose: Connects the PostgresStore (built in Plan 01) to the startup path, adds Docker Compose profiles for PostgreSQL deployments, creates build-tagged integration test helpers, and fixes the UNIQUE constraint detection to work across both database backends.
Output: Updated main.go with DATABASE_URL branching, compose files with postgres profiles, build-tagged test helper, cross-dialect error handling fix.
</objective>

<execution_context>
@$HOME/.claude/get-shit-done/workflows/execute-plan.md
@$HOME/.claude/get-shit-done/templates/summary.md
</execution_context>

<context>
@.planning/PROJECT.md
@.planning/ROADMAP.md
@.planning/STATE.md
@.planning/phases/03-postgresql-support/03-CONTEXT.md
@.planning/phases/03-postgresql-support/03-RESEARCH.md
@.planning/phases/03-postgresql-support/03-01-SUMMARY.md

@cmd/diunwebhook/main.go
@pkg/diunwebhook/diunwebhook.go
@pkg/diunwebhook/export_test.go
@compose.yml
@compose.dev.yml

<interfaces>
<!-- From Plan 01 outputs -->
From pkg/diunwebhook/postgres_store.go:
```go
func NewPostgresStore(db *sql.DB) *PostgresStore
```

From pkg/diunwebhook/migrate.go:
```go
func RunSQLiteMigrations(db *sql.DB) error
func RunPostgresMigrations(db *sql.DB) error
```

From pkg/diunwebhook/store.go:
```go
type Store interface { ... } // 9 methods
```

From pkg/diunwebhook/diunwebhook.go:
```go
func NewServer(store Store, webhookSecret string) *Server
```
</interfaces>
</context>

<tasks>

<task type="auto">
  <name>Task 1: Wire DATABASE_URL branching in main.go and fix cross-dialect UNIQUE detection</name>
  <read_first>
    - cmd/diunwebhook/main.go (current SQLite-only startup to add branching)
    - pkg/diunwebhook/diunwebhook.go (TagsHandler line 172 - UNIQUE detection to fix)
    - pkg/diunwebhook/postgres_store.go (verify NewPostgresStore exists from Plan 01)
    - pkg/diunwebhook/migrate.go (verify RunSQLiteMigrations and RunPostgresMigrations exist from Plan 01)
  </read_first>
  <files>cmd/diunwebhook/main.go, pkg/diunwebhook/diunwebhook.go</files>
  <action>
**1. Update `cmd/diunwebhook/main.go`** to branch on `DATABASE_URL` per D-07, D-08, D-09.

Replace the current database setup block (lines 18-33) with DATABASE_URL branching. The full main function should:

```go
package main

import (
    "context"
    "database/sql"
    "errors"
    "log"
    "net/http"
    "os"
    "os/signal"
    "syscall"
    "time"

    diun "awesomeProject/pkg/diunwebhook"
    _ "github.com/jackc/pgx/v5/stdlib"
    _ "modernc.org/sqlite"
)

func main() {
    databaseURL := os.Getenv("DATABASE_URL")
    var store diun.Store
    if databaseURL != "" {
        db, err := sql.Open("pgx", databaseURL)
        if err != nil {
            log.Fatalf("sql.Open postgres: %v", err)
        }
        if err := diun.RunPostgresMigrations(db); err != nil {
            log.Fatalf("RunPostgresMigrations: %v", err)
        }
        store = diun.NewPostgresStore(db)
        log.Println("Using PostgreSQL database")
    } else {
        dbPath := os.Getenv("DB_PATH")
        if dbPath == "" {
            dbPath = "./diun.db"
        }
        db, err := sql.Open("sqlite", dbPath)
        if err != nil {
            log.Fatalf("sql.Open sqlite: %v", err)
        }
        if err := diun.RunSQLiteMigrations(db); err != nil {
            log.Fatalf("RunSQLiteMigrations: %v", err)
        }
        store = diun.NewSQLiteStore(db)
        log.Printf("Using SQLite database at %s", dbPath)
    }

    // ... rest of main unchanged (secret, server, mux, httpSrv, graceful shutdown)
}
```

Key changes:
- Add blank import `_ "github.com/jackc/pgx/v5/stdlib"` to register "pgx" driver name
- `DATABASE_URL` present -> `sql.Open("pgx", databaseURL)` -> `RunPostgresMigrations` -> `NewPostgresStore`
- `DATABASE_URL` absent -> existing SQLite path with `RunSQLiteMigrations` (renamed in Plan 01)
- Log `"Using PostgreSQL database"` or `"Using SQLite database at %s"` per D-09
- Keep all existing code after the store setup unchanged (secret, server, mux, httpSrv, shutdown)

**2. Fix cross-dialect UNIQUE constraint detection in `pkg/diunwebhook/diunwebhook.go`.**

In the `TagsHandler` method, line 172, change:
```go
if strings.Contains(err.Error(), "UNIQUE") {
```
to:
```go
if strings.Contains(strings.ToLower(err.Error()), "unique") {
```

Why: SQLite errors contain uppercase "UNIQUE" (e.g., `UNIQUE constraint failed: tags.name`). PostgreSQL/pgx errors contain lowercase "unique" (e.g., `duplicate key value violates unique constraint "tags_name_key"`). Case-insensitive matching ensures 409 Conflict is returned for both backends.
  </action>
  <verify>
    <automated>cd /home/jean-luc-makiola/Development/projects/DiunDashboard && go build ./... && go test -v -count=1 ./pkg/diunwebhook/ 2>&1 | tail -5</automated>
  </verify>
  <acceptance_criteria>
    - cmd/diunwebhook/main.go contains `databaseURL := os.Getenv("DATABASE_URL")`
    - cmd/diunwebhook/main.go contains `sql.Open("pgx", databaseURL)`
    - cmd/diunwebhook/main.go contains `diun.RunPostgresMigrations(db)`
    - cmd/diunwebhook/main.go contains `diun.NewPostgresStore(db)`
    - cmd/diunwebhook/main.go contains `log.Println("Using PostgreSQL database")`
    - cmd/diunwebhook/main.go contains `log.Printf("Using SQLite database at %s", dbPath)`
    - cmd/diunwebhook/main.go contains `_ "github.com/jackc/pgx/v5/stdlib"`
    - cmd/diunwebhook/main.go contains `diun.RunSQLiteMigrations(db)` (not RunMigrations)
    - pkg/diunwebhook/diunwebhook.go contains `strings.Contains(strings.ToLower(err.Error()), "unique")`
    - pkg/diunwebhook/diunwebhook.go does NOT contain `strings.Contains(err.Error(), "UNIQUE")` (old pattern removed)
    - `go build ./...` exits 0
    - `go test -count=1 ./pkg/diunwebhook/` exits 0
  </acceptance_criteria>
  <done>main.go branches on DATABASE_URL to select PostgreSQL or SQLite. pgx/v5/stdlib is blank-imported to register the driver. Startup log identifies the active backend. UNIQUE detection is case-insensitive for cross-dialect compatibility. All existing tests pass.</done>
</task>

<task type="auto">
  <name>Task 2: Add Docker Compose postgres profiles and build-tagged test helper</name>
  <read_first>
    - compose.yml (current production compose to add postgres profile)
    - compose.dev.yml (current dev compose to add postgres profile)
    - pkg/diunwebhook/export_test.go (pattern for NewTestPostgresServer)
    - Dockerfile (verify no changes needed -- pgx/v5 is pure Go, CGO_ENABLED=0 is fine)
  </read_first>
  <files>compose.yml, compose.dev.yml, pkg/diunwebhook/postgres_test.go</files>
  <action>
**1. Update `compose.yml`** (production) to add postgres profile per D-14, D-15, D-16:

```yaml
# Minimum Docker Compose v2.20 required for depends_on.required
services:
  app:
    image: gitea.jeanlucmakiola.de/makiolaj/diundashboard:latest
    ports:
      - "8080:8080"
    environment:
      - WEBHOOK_SECRET=${WEBHOOK_SECRET:-}
      - PORT=${PORT:-8080}
      - DB_PATH=/data/diun.db
      - DATABASE_URL=${DATABASE_URL:-}
    volumes:
      - diun-data:/data
    restart: unless-stopped
    depends_on:
      postgres:
        condition: service_healthy
        required: false

  postgres:
    image: postgres:17-alpine
    profiles:
      - postgres
    environment:
      POSTGRES_USER: ${POSTGRES_USER:-diun}
      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:-diun}
      POSTGRES_DB: ${POSTGRES_DB:-diundashboard}
    volumes:
      - postgres-data:/var/lib/postgresql/data
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U ${POSTGRES_USER:-diun}"]
      interval: 5s
      timeout: 5s
      retries: 5
      start_period: 10s
    restart: unless-stopped

volumes:
  diun-data:
  postgres-data:
```

Default `docker compose up` still uses SQLite (DATABASE_URL is empty string, app falls back to DB_PATH).
`docker compose --profile postgres up` starts the postgres service; user sets `DATABASE_URL=postgres://diun:diun@postgres:5432/diundashboard?sslmode=disable` in .env.

**2. Update `compose.dev.yml`** to add postgres profile for local development:

```yaml
services:
  app:
    build: .
    ports:
      - "8080:8080"
    environment:
      - WEBHOOK_SECRET=${WEBHOOK_SECRET:-}
      - DATABASE_URL=${DATABASE_URL:-}
    restart: unless-stopped
    depends_on:
      postgres:
        condition: service_healthy
        required: false

  postgres:
    image: postgres:17-alpine
    profiles:
      - postgres
    ports:
      - "5432:5432"
    environment:
      POSTGRES_USER: ${POSTGRES_USER:-diun}
      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:-diun}
      POSTGRES_DB: ${POSTGRES_DB:-diundashboard}
    volumes:
      - postgres-data:/var/lib/postgresql/data
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U ${POSTGRES_USER:-diun}"]
      interval: 5s
      timeout: 5s
      retries: 5
      start_period: 10s
    restart: unless-stopped

volumes:
  postgres-data:
```

Dev compose exposes port 5432 on host for direct psql access during development.

**3. Create `pkg/diunwebhook/postgres_test.go`** with build tag per D-17, D-19:

```go
//go:build postgres

package diunwebhook

import (
    "database/sql"
    "os"

    _ "github.com/jackc/pgx/v5/stdlib"
)

// NewTestPostgresServer constructs a Server backed by a PostgreSQL database.
// Requires a running PostgreSQL instance. Set TEST_DATABASE_URL to override
// the default connection string.
func NewTestPostgresServer() (*Server, error) {
    databaseURL := os.Getenv("TEST_DATABASE_URL")
    if databaseURL == "" {
        databaseURL = "postgres://diun:diun@localhost:5432/diundashboard_test?sslmode=disable"
    }
    db, err := sql.Open("pgx", databaseURL)
    if err != nil {
        return nil, err
    }
    if err := RunPostgresMigrations(db); err != nil {
        return nil, err
    }
    store := NewPostgresStore(db)
    return NewServer(store, ""), nil
}
```

This file is in the `diunwebhook` package (internal, same as export_test.go pattern). The `//go:build postgres` tag ensures it only compiles when explicitly requested with `go test -tags postgres`. Without the tag, `go test ./pkg/diunwebhook/` skips this file entirely -- no pgx import, no PostgreSQL dependency.
  </action>
  <verify>
    <automated>cd /home/jean-luc-makiola/Development/projects/DiunDashboard && go build ./... && docker compose config --quiet 2>&1; echo "exit: $?"</automated>
  </verify>
  <acceptance_criteria>
    - compose.yml contains `profiles:` under the postgres service
    - compose.yml contains `- postgres` (profile name)
    - compose.yml contains `postgres:17-alpine`
    - compose.yml contains `pg_isready`
    - compose.yml contains `required: false` (conditional depends_on)
    - compose.yml contains `DATABASE_URL=${DATABASE_URL:-}`
    - compose.yml contains `postgres-data:` in volumes
    - compose.dev.yml contains `profiles:` under the postgres service
    - compose.dev.yml contains `- postgres` (profile name)
    - compose.dev.yml contains `"5432:5432"` (exposed for dev)
    - compose.dev.yml contains `required: false`
    - compose.dev.yml contains `DATABASE_URL=${DATABASE_URL:-}`
    - pkg/diunwebhook/postgres_test.go contains `//go:build postgres`
    - pkg/diunwebhook/postgres_test.go contains `func NewTestPostgresServer()`
    - pkg/diunwebhook/postgres_test.go contains `sql.Open("pgx", databaseURL)`
    - pkg/diunwebhook/postgres_test.go contains `RunPostgresMigrations(db)`
    - pkg/diunwebhook/postgres_test.go contains `NewPostgresStore(db)`
    - pkg/diunwebhook/postgres_test.go contains `TEST_DATABASE_URL`
    - `go build ./...` exits 0 (postgres_test.go is not compiled without build tag)
    - `go test -count=1 ./pkg/diunwebhook/` exits 0 (SQLite tests still pass, postgres_test.go skipped)
  </acceptance_criteria>
  <done>Docker Compose files support optional PostgreSQL via profiles. Default deploy remains SQLite-only. Build-tagged test helper exists for PostgreSQL integration testing. Dockerfile needs no changes (pgx/v5 is pure Go).</done>
</task>

</tasks>

<verification>
1. `go build ./...` succeeds
2. `go test -v -count=1 ./pkg/diunwebhook/` passes (all existing SQLite tests)
3. `docker compose config` validates without errors
4. `docker compose --profile postgres config` shows postgres service
5. `grep -c "DATABASE_URL" cmd/diunwebhook/main.go` returns at least 1
6. `grep "strings.ToLower" pkg/diunwebhook/diunwebhook.go` shows case-insensitive UNIQUE check
</verification>

<success_criteria>
- DATABASE_URL present: app opens pgx connection, runs PostgreSQL migrations, creates PostgresStore, logs "Using PostgreSQL database"
- DATABASE_URL absent: app opens sqlite connection, runs SQLite migrations, creates SQLiteStore, logs "Using SQLite database at {path}"
- `docker compose up` (no profile) works with SQLite only
- `docker compose --profile postgres up` starts PostgreSQL service with health check
- Build-tagged test helper available for PostgreSQL integration tests
- UNIQUE constraint detection works for both SQLite and PostgreSQL error messages
- All existing SQLite tests continue to pass
</success_criteria>

<output>
After completion, create `.planning/phases/03-postgresql-support/03-02-SUMMARY.md`
</output>