fix: scope default build to desktop-only, document build target in AGENTS.md

The unfiltered `turbo run build` was building all 5 workspaces including
marketing. Since desktop is the primary target, `bun build` now matches
`build:desktop`. AGENTS.md updated so agents know not to include marketing
in default builds.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: alecramos-sudo

AGENTS.md

@@ -23,10 +23,16 @@ If a tradeoff is required, choose correctness and robustness over short-term con
 
 Long term maintainability is a core priority. If you add new functionality, first check if there is shared logic that can be extracted to a separate module. Duplicate logic across multiple files is a code smell and should be avoided. Don't be afraid to change existing code. Don't take shortcuts by just adding local logic to solve a problem.
 
+## Build Target
+
+The primary build target is the **desktop app** (`apps/desktop`). `bun build` and `bun dev:desktop` build only what's needed for it. `apps/marketing` is a separate landing site — don't include it in default builds or dev workflows.
+
 ## Package Roles
 
+- `apps/desktop`: Electron desktop app. This is the primary distribution target.
 - `apps/server`: Node.js WebSocket server. Wraps Codex app-server (JSON-RPC over stdio), serves the React web app, and manages provider sessions.
 - `apps/web`: React/Vite UI. Owns session UX, conversation/event rendering, and client-side state. Connects to the server via WebSocket.
+- `apps/marketing`: Astro landing/marketing site. Separate from the app — has its own `build:marketing` and `dev:marketing` scripts. Do not include in default builds.
 - `packages/contracts`: Shared effect/Schema schemas and TypeScript contracts for provider events, WebSocket protocol, and model/session types. Keep this package schema-only — no runtime logic.
 - `packages/shared`: Shared runtime utilities consumed by both server and web. Uses explicit subpath exports (e.g. `@t3tools/shared/git`) — no barrel index.
 

package.json

@@ -34,7 +34,7 @@
     "start:desktop": "turbo run start --filter=@t3tools/desktop",
     "start:marketing": "turbo run preview --filter=@t3tools/marketing",
     "start:mock-update-server": "bun run scripts/mock-update-server.ts",
-    "build": "turbo run build",
+    "build": "turbo run build --filter=@t3tools/desktop --filter=t3",
     "build:marketing": "turbo run build --filter=@t3tools/marketing",
     "build:desktop": "turbo run build --filter=@t3tools/desktop --filter=t3",
     "typecheck": "turbo run typecheck",