> Part of the **Plugin & Package System** epic #20. Phase 2 (foundation/MVP). **Keystone issue — highest risk, do early.** `t:breaking`. ## Goal Give every Turian project a **real `build.zig.zon`** and refactor game-build codegen so dependencies resolve through Zig's package manager (`b.dependency()`), not hardcoded SDK paths. This is the foundation that lets the rest of the epic delegate dependency resolution to Zig. ## Current state (what must change) - `editor/ProjectOps.zig` writes only a sentinel `project.json` = `{"turian_version":"0.16"}`. There is **no `build.zig.zon` and no project-owned `build.zig`**. - `editor/GameCodegen.zig` `generateBuildZig()` emits the game's `build.zig` as a string that wires **every** dependency (math, oap, engine, guid, serde, editor, gpu, render) via `.cwd_relative` **absolute paths** computed by `editor/SdkLayout.zig` from `TURIAN_*` env vars or the installed SDK layout (`<sdk>/deps/*`). - User scripts become `script_N_mod` modules created from absolute file paths. - `editor/GameBuild.zig` writes the generated `build.zig` + `main.zig` into `<project>/.cache/` and runs `zig build` there. Because there's no `build.zig.zon`, a project cannot today declare third-party dependencies and Zig's fetcher/resolver is never used for project deps. ## Design 1. **New project files** (extend `ProjectOps.newProject`): - `build.zig.zon` with the project `name`, `version`, `fingerprint`, `minimum_zig_version`, and an empty `.dependencies` block. The engine SDK itself is referenced here (path in dev / git in SDK mode) so the project's deps and the engine share one resolution graph. 2. **Codegen refactor** (`editor/GameCodegen.zig`): - Generated `.cache/build.zig` resolves engine + first-party deps via `b.dependency("engine", .{})` etc. instead of `.cwd_relative` absolute paths, **OR** keep the `.cwd_relative` path for in-tree dev and add a clean injection seam (see below). Pick the approach in the issue; the requirement is that **external project dependencies declared in the project's `build.zig.zon` are reachable from the generated build**. - The `.cache/build.zig.zon` must be generated/derived from the project's `build.zig.zon` so `b.dependency()` calls resolve. Decide: generate a `.cache/build.zig.zon` that `.path`-includes the project root deps, or run the build from the project root. 3. **Preserve the three-layer SDK resolution** (`SdkLayout.zig`: env > SDK > baked) for the *engine/first-party* deps — only *project/third-party* deps move to `build.zig.zon`. 4. **Injection seam for later issues:** expose a single place where #E (source modules), #F (native libs) and #D (asset roots) append to the generated build. Define the data structure (e.g. extend `BuildConfig` / `RuntimeConfig` with `extra_modules`, `extra_native`, `extra_asset_roots`). ## Tasks - [ ] `ProjectOps.newProject` writes a valid `build.zig.zon` (name/version/fingerprint/min-zig/empty deps) - [ ] Decide & document the resolution model: project root build vs. `.cache` build with derived `build.zig.zon` - [ ] Refactor `GameCodegen.generateBuildZig` to make project `build.zig.zon` dependencies reachable in the generated build via `b.dependency()` - [ ] Keep engine/first-party SDK resolution working in all three modes (in-tree dev, installed SDK, `TURIAN_*` overrides) — verify `turian-cli build examples/basic-project` still links - [ ] Add the build-injection seam (`extra_modules` / `extra_native` / `extra_asset_roots` on the config) consumed by #D/#E/#F - [ ] Migrate existing `examples/*` projects to include a `build.zig.zon` (migration note for existing user projects) - [ ] Update `editor/PlayBuild.zig` if it shares the codegen path (it mirrors `GameBuild` per the play-mode design) - [ ] `zig fmt` + `zig build test`; verify all `examples/` still build via `turian-cli build` ## Acceptance criteria - `turian-cli new-project` produces a project containing a valid `build.zig.zon`. - A project can declare a third-party Zig dependency in its `build.zig.zon` and the generated game build resolves it via `b.dependency()`. - All existing `examples/` still build and run headlessly (`turian-cli build examples/basic-project`). - A documented injection seam exists for source modules, native libs, and asset roots. - Engine/first-party resolution still works in dev, SDK, and env-override modes. ## Dependencies Depends on #A (manifest decides what the project records about installed packages). Blocks #C, #D, #E, #F. ## Out of scope Actually consuming packages — this only proves a project `build.zig.zon` works end-to-end and exposes the seam.