diff --git a/AGENTS.md b/AGENTS.md
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+++ b/AGENTS.md
@@ -4,6 +4,14 @@
 
 This repository is a Thunderbird Manifest V3 Filelink/cloudFile provider scaffold for PsiTransfer. Treat it as an integration-in-progress, not a finished provider.
 
+## Thunderbird add-on conventions
+
+This repository is not the only Thunderbird add-on in this workspace. When implementation details are unclear, check the maintainer's primary add-on conventions here:
+
+- `https://git.jordanwages.com/wagesj45/Sortana.git`
+
+If `/tmp/Sortana` does not already exist, the agent may clone that repository into `/tmp` and inspect it for implementation patterns, project structure, and Thunderbird-specific conventions that should also be followed here when they do not conflict with this repository's PsiTransfer-specific rules.
+
 ## Required source of truth
 
 Before changing PsiTransfer integration behavior: