---
phase: 01-foundation
plan: 01
subsystem: infra
tags: [mill, zio, zio-http, scala3, hocon]

# Dependency graph
requires: []
provides:
  - Mill 1.1.1 build system with Scala 3.3.4
  - ZIO HTTP server with health endpoint
  - HOCON configuration with env overrides
  - Application entry point pattern
affects: [01-02, 01-03, all-phases]

# Tech tracking
tech-stack:
  added:
    - Mill 1.1.1
    - Scala 3.3.4
    - ZIO 2.1.14
    - zio-http 3.0.1
    - zio-config 4.0.2
    - zio-config-typesafe 4.0.2
    - zio-config-magnolia 4.0.2
    - quill-jdbc-zio 4.8.5
    - postgresql 42.7.4
    - flyway-core 10.21.0
  patterns:
    - ZIOAppDefault with bootstrap ConfigProvider
    - Routes composition via object aggregation
    - HOCON config with env variable overrides

key-files:
  created:
    - build.mill
    - .mill-version
    - .gitignore
    - summercms/src/Main.scala
    - summercms/src/api/Routes.scala
    - summercms/src/api/HealthRoutes.scala
    - summercms/src/config/AppConfig.scala
    - summercms/resources/application.conf
  modified: []

key-decisions:
  - "Mill 1.1.1 for Java 25 compatibility (0.12.x uses ASM that doesn't support class file version 69)"
  - "Use mvnDeps and mvn interpolator (ivy deprecated in Mill 1.x)"
  - "Use _root_.config import to avoid shadowing from zio.config"

patterns-established:
  - "Config pattern: Case classes with zio-config-magnolia derivation"
  - "Route pattern: Object with routes val, composed in Routes.scala"
  - "Main pattern: ZIOAppDefault with bootstrap for ConfigProvider"

# Metrics
duration: 39min
completed: 2026-02-04
---

# Phase 01 Plan 01: Mill Build and ZIO HTTP Server Summary

**Mill 1.1.1 build with Scala 3.3.4, ZIO HTTP server on port 8080, HOCON configuration with environment overrides**

## Performance

- **Duration:** 39 min
- **Started:** 2026-02-04T20:04:29Z
- **Completed:** 2026-02-04T20:44:00Z
- **Tasks:** 3
- **Files created:** 8

## Accomplishments

- Mill build system configured with all ZIO dependencies for Phase 1
- Working HTTP server with /health endpoint returning "ok"
- Configuration infrastructure using zio-config-magnolia for automatic derivation
- ASCII sun banner displayed on server startup

## Task Commits

Each task was committed atomically:

1. **Task 1: Create Mill build configuration** - `aedb45f` (feat)
2. **Task 2: Create project structure and configuration** - `4278b84` (feat)
3. **Task 3: Create HTTP routes and Main entry point** - `3757cf8` (feat)

## Files Created

- `build.mill` - Mill build configuration with Scala 3.3.4 and ZIO dependencies
- `.mill-version` - Pins Mill version to 1.1.1
- `.gitignore` - Excludes Mill artifacts, IDE files, OS files
- `summercms/src/Main.scala` - ZIOAppDefault entry point with banner
- `summercms/src/api/Routes.scala` - Route composition point
- `summercms/src/api/HealthRoutes.scala` - GET /health endpoint
- `summercms/src/config/AppConfig.scala` - ServerConfig, DatabaseConfig, AppConfig case classes
- `summercms/resources/application.conf` - HOCON config with env overrides

## Decisions Made

1. **Mill 1.1.1 instead of 0.12.x** - System Java 25 (class file version 69) requires newer Mill with updated ASM library
2. **mvnDeps instead of ivyDeps** - Mill 1.x renamed the dependency method
3. **_root_.config import** - Avoids shadowing from `zio.*` importing `zio.config`

## Deviations from Plan

### Auto-fixed Issues

**1. [Rule 3 - Blocking] Updated Mill version for Java 25 compatibility**
- **Found during:** Task 1
- **Issue:** Mill 0.12.11 ASM library doesn't support Java 25 class file version 69
- **Fix:** Downloaded Mill 1.1.1 launcher, updated .mill-version
- **Files modified:** .mill-version, downloaded ./mill launcher
- **Verification:** `./mill resolve _` succeeds
- **Committed in:** aedb45f

**2. [Rule 3 - Blocking] Added .gitignore for Mill artifacts**
- **Found during:** Task 1
- **Issue:** Build artifacts (out/, mill executable) would be committed without gitignore
- **Fix:** Created .gitignore excluding Mill artifacts, IDE files, OS files
- **Files modified:** .gitignore (new file)
- **Verification:** `git status --short` no longer shows out/ or mill
- **Committed in:** aedb45f

**3. [Rule 1 - Bug] Fixed import shadowing with zio.config**
- **Found during:** Task 3
- **Issue:** `import zio.*` brings `zio.config` into scope, shadowing local `config` package
- **Fix:** Used `_root_.config.{AppConfig as SummerConfig}` import
- **Files modified:** summercms/src/Main.scala
- **Verification:** `./mill summercms.compile` succeeds
- **Committed in:** 3757cf8

---

**Total deviations:** 3 auto-fixed (2 blocking, 1 bug)
**Impact on plan:** All auto-fixes necessary for correctness. No scope creep.

## Issues Encountered

- SLF4J warning about missing StaticLoggerBinder - benign, zio-http works with NOP logger. Will be resolved when adding proper logging in later phases.

## User Setup Required

None - no external service configuration required.

## Next Phase Readiness

- Build system ready for database integration (Plan 01-02)
- All ZIO dependencies already declared for database layer
- Configuration pattern established for adding more settings
- Ready to add /ready endpoint once database is connected

---
*Phase: 01-foundation*
*Completed: 2026-02-04*