add cleanup-branch skill for post-PR branch cleanup (closes #42) (#43)

Author: TheJavaGuy

.claude/skills/cleanup-branch/SKILL.md

@@ -0,0 +1,21 @@
+---
+name: cleanup-branch
+description: Switches to master, pulls latest changes, and deletes the branch you were on. Safe to use after a PR is merged.
+disable-model-invocation: true
+allowed-tools: Bash
+---
+
+Run the following commands in order:
+
+```bash
+# Capture current branch name before switching
+BRANCH=$(git rev-parse --abbrev-ref HEAD)
+
+# Switch to master and pull
+git checkout master && git pull
+
+# Delete the feature branch (-D handles branches already merged via remote)
+[ "$BRANCH" != "master" ] && git branch -D "$BRANCH" && echo "Deleted branch: $BRANCH"
+```
+
+Report the branch that was deleted and the current state of master (latest commit).

LEARNINGS.md

@@ -81,6 +81,12 @@ return faker.bothify(pattern, true);
 
 **Solution**: Write the body to a temp file and use `--body-file /tmp/issue-body.md` instead of `--body "$(cat ...)"`.
 
+### 7. Skills with `disable-model-invocation: true` cannot be called via the Skill tool
+
+**Problem**: Invoking a skill that has `disable-model-invocation: true` via the Skill tool raises an error and wastes a round-trip.
+
+**Solution**: Follow the SKILL.md instructions manually, step by step. The `disable-model-invocation` flag means the skill is a pure prompt template — not a model-callable tool.
+
 ---
 
 *Last updated: 2026-03-01*