diff --git a/CLAUDE.md b/CLAUDE.md
index cc20fe13..36fcdebb 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -166,6 +166,24 @@ nix.gc.dates = lib.mkForce "daily";
 
 - After arriving at a working solution through trial and error, proactively ask whether the finding should be recorded in CLAUDE.md (or Basic Memory) for future sessions.
 
+## Commit Identity
+
+When making git commits, disable GPG signing — it requires an interactive passphrase and will hang. Agent authorship is already recorded via the `Co-Authored-By` trailer. Note that `-c` and `-m` cannot be used together in git; use `GIT_CONFIG_COUNT` env vars instead:
+
+```bash
+GIT_CONFIG_COUNT=1 \
+  GIT_CONFIG_KEY_0=commit.gpgsign GIT_CONFIG_VALUE_0=false \
+  git commit -m "..."
+```
+
+The same applies to `gt modify`:
+
+```bash
+GIT_CONFIG_COUNT=1 \
+  GIT_CONFIG_KEY_0=commit.gpgsign GIT_CONFIG_VALUE_0=false \
+  gt modify --no-edit
+```
+
 ## Code style
 
 - All files should end with a newline.