diff --git a/AGENTS.md b/AGENTS.md
index e8fd43b..547f116 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -7,3 +7,7 @@ Sessions are automatic (based on terminal/agent context). Optional:
 - td session --new to force a new session in the same context
 
 Use td usage -q after first read.
+
+## CRITICAL: Sub-agents must NOT call td
+
+Only the orchestrating Claude instance may call `td` commands. If you are a sub-agent spawned to implement a task, do NOT run `td start`, `td close`, `td update`, or any other `td` command. Concurrent writes to the SQLite database from parallel agents will corrupt it. The orchestrator manages all task lifecycle calls.
diff --git a/CLAUDE.md b/CLAUDE.md
index 5b53d70..8753418 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -7,6 +7,7 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 - **Commit after every task**: When a task is complete, stage all changed files and create a git commit before marking the task done.
 - **Keep documentation current**: Update `CLAUDE.md` with any new commands, architecture details, or setup steps introduced by your task. Update `PRD.md` only if scope/design decisions changed.
 - **Mark tasks in td**: `td start <id>` when beginning, `td close <id>` when done.
+- **Only the orchestrator touches td**: Sub-agents must never call `td` commands directly. Concurrent `td` writes from parallel agents corrupt the SQLite database. The orchestrator handles all `td start`/`td close` calls before and after delegating to sub-agents.
 
 ## Task Management