diff --git a/packages/opencode/specs/simulation-phases.md b/packages/opencode/specs/simulation-phases.md
index 3bff4a9c5b7..6c00f35e2ea 100644
--- a/packages/opencode/specs/simulation-phases.md
+++ b/packages/opencode/specs/simulation-phases.md
@@ -10,6 +10,18 @@ Goal: start the normal app in simulation mode and inspect/drive the TUI through
 
 This phase proves the core shape without swapping every foundational layer yet.
 
+Implementation checklist:
+
+- [ ] Add `OPENCODE_SIMULATION=1` activation in TUI startup.
+- [ ] Add simulation trace service with in-memory append-only records.
+- [ ] Add OpenTUI UI state extraction for screen, focus, elements, and generated actions.
+- [ ] Add OpenTUI UI action execution for typing, keys, enter, arrows, focus, and click.
+- [ ] Add TUI-owned JSON-RPC WebSocket server on `127.0.0.1:40900+`.
+- [ ] Expose `ui.state`, `ui.action`, `ui.render`.
+- [ ] Expose `trace.list`, `trace.clear`, `trace.export`.
+- [ ] Ensure fake and visible renderer paths share the same action protocol.
+- [ ] Verify a local driver can inspect state and execute a real TUI input.
+
 Scope:
 
 - Add `OPENCODE_SIMULATION=1` activation.