diff --git a/CHANGELOG.md b/CHANGELOG.md
index 17235b6..adbfeb3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 _Next: closed-loop refiner (critique→repair→re-critique with transaction-stack isolation), pre-plan clarification pass, ISO 286 fit-table lookup (H7/g6 → deviations), and a local-VLM visual judge._
 
+### Fixed
+- **Install from source** — `pip install -e ".[full]"` failed at
+  "Preparing editable metadata" because the flat layout has no directory
+  matching the project name, so hatchling could not infer which files to ship.
+  `pyproject.toml` now declares the wheel file selection explicitly
+  (`server.py`, `config.py`, `security.py`, `backends/`, `engineering/`). (#2)
+
 ## [1.2.0] — 2026-07-07
 
 Production-ISO parity + a measurable quality moat. **360 tests, ruff-clean.** Tool count: 111 → 116.
diff --git a/pyproject.toml b/pyproject.toml
index e818e6a..7c61041 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -39,6 +39,11 @@ dev-dependencies = [
 requires = ["hatchling"]
 build-backend = "hatchling.build"
 
+[tool.hatch.build.targets.wheel]
+# Flat layout: no directory matches the project name, so hatchling needs an
+# explicit file selection (GH issue #2). server.py imports config + security.
+only-include = ["server.py", "config.py", "security.py", "backends", "engineering"]
+
 [tool.ruff]
 line-length = 100
 target-version = "py311"