docs: add portfolio context recovery note

Author: saagpatel

AGENTS.md

@@ -0,0 +1,43 @@
+<!-- portfolio-context:start -->
+# Portfolio Context
+
+## What This Project Is
+
+Desktop Terrarium is a native Bevy desktop app that grows a layered 2D terrarium based on real keyboard activity and time. Plants advance through growth stages, weather cycles through particle-rich states, critters appear after focus streaks, and state persists locally.
+
+## Current State
+
+The repo is active local desktop/game work. Existing untracked folders are generated local artifacts, so this recovery pass should only add the new context file.
+
+## Stack
+
+| Layer | Technology |
+|-------|------------|
+| Language | Rust 2021 |
+| Engine | Bevy 0.15 |
+| Serialization | serde + serde_json |
+| Persistence | JSON via `dirs` (platform data dir) |
+| Idle detection | macOS CoreGraphics — CGEventSourceSecondsSinceLastEventType |
+
+## How To Run
+
+```bash
+# Run
+cargo run
+
+# Release build
+cargo build --release
+```
+
+## Known Risks
+
+- Idle detection depends on macOS CoreGraphics, so cross-platform claims need explicit verification.
+- Terrarium state persists to the platform data directory; avoid destructive state resets without operator approval.
+- Generated `.artifacts` and `.perf-results` folders are local outputs and should not be swept into source commits.
+- Keep Bevy performance and 800x600/resizable window behavior intact when changing rendering.
+
+## Next Recommended Move
+
+Add only the context file for this recovery pass, then keep future work focused on activity-driven growth, local persistence, and Bevy rendering stability.
+
+<!-- portfolio-context:end -->