fix: add PR merge conflict check to dev agent workflow

Dev agent should check if PR has merge conflicts before asking for review.
This prevents approving a PR that has conflicts, which could introduce
new errors after rebase.

Changes:
- Add conflict check step in workflow for both with/without user message cases
- Use mergeable field from PR API to detect conflicts
- Instructions to rebase and resolve conflicts if mergeable: false

skills/kugetsu/scripts/kugetsu-session.sh

@@ -272,29 +272,44 @@ build_dev_agent_message() {
     
     if [ -n "$user_message" ]; then
         cat <<EOF
-You are continuing work on $issue_ref. A PR likely already exists.
+You are assigned to work on $issue_ref.
 
-IMPORTANT - Review workflow:
-1. First, check if PR exists: curl -s "https://$instance/api/v1/repos/$owner/$repo/pulls?state=open" -H "Authorization: Bearer \$GITEA_TOKEN" | grep -i "$number"
-2. Get PR comments: curl -s "https://$instance/api/v1/repos/$owner/$repo/issues/$number/comments" -H "Authorization: Bearer \$GITEA_TOKEN"
-3. Get PR reviews: curl -s "https://$instance/api/v1/repos/$owner/$repo/pulls/$number/reviews" -H "Authorization: Bearer \$GITEA_TOKEN"
+IMPORTANT: Follow the workflow below as your guideline, but prioritize the delegator's message.
 
-You may need to:
-- Make code changes and push to the same branch
-- Reply to PR comments using: curl -X POST "https://$instance/api/v1/repos/$owner/$repo/issues/$number/comments" -H "Authorization: Bearer \$GITEA_TOKEN" -H "Content-Type: application/json" -d '{"body":"Your reply here"}'
-- Or do both
+Workflow:
+1. Read the issue at $instance/$owner/$repo/issues/$number AND all comments on that issue
+2. Check if a PR already exists for this issue
+   - If PR exists and is open, review it and learn from it
+   - CRITICAL: Check if PR has merge conflicts before asking for review:
+     - Use: curl -s "https://$instance/api/v1/repos/$owner/$repo/pulls/$number" -H "Authorization: Bearer \$GITEA_TOKEN"
+     - If "mergeable": false, there ARE conflicts - you MUST resolve them FIRST
+     - To resolve: cd to worktree, git fetch origin, git rebase origin/main, resolve conflicts, git rebase --continue, git push --force-with-lease
+     - Only after resolving conflicts (mergeable: true) can you ask for review
+   - If PR makes sense to continue, work on it instead
+   - If PR is not worth continuing, create a new branch/PR but explain in PR description why you're creating a new one instead of continuing the existing PR
+3. Read README.md (if exists) to understand the general concept of this repository
+4. Read CONTRIBUTING.md (if exists) to understand how to contribute
+   - If CONTRIBUTING.md doesn't exist, follow steps 5-9 as your guideline
+5. Explore the repository to understand the codebase
+6. If anything is unclear, post a comment on the issue asking for clarification before implementing
+7. Implement the solution
+8. Create a branch named fix/issue-$number and implement the fix
+9. Create a PR when the implementation is complete using: tea pr create --repo $owner/$repo --title "Your PR title" --body "PR description"
+   - Make sure you are logged in with: tea login add --name gitea --token \$GITEA_TOKEN --url https://$instance
+   - If tea is not available, use: curl -X POST "https://$instance/api/v1/repos/$owner/$repo/pulls" -H "Authorization: Bearer \$GITEA_TOKEN" -H "Content-Type: application/json" -d '{"title":"PR Title","head":"branch-name","base":"main","body":"PR description"}'
 
-MERGING: If instructed to merge, you MUST confirm approval first before merging:
-- Check for PR approval via: curl -s "https://$instance/api/v1/repos/$owner/$repo/pulls/$number/reviews" -H "Authorization: Bearer \$GITEA_TOKEN"
-- Check for "lgtm" or "approved" in comments: curl -s "https://$instance/api/v1/repos/$owner/$repo/issues/$number/comments" -H "Authorization: Bearer \$GITEA_TOKEN"
-- Only merge if you see approval OR the instruction explicitly says to merge (e.g., "merge the PR", "please merge", "go ahead and merge")
-- To merge: tea pr merge --repo $owner/$repo $number --style merge
-- If no approval yet, reply asking for review/approval first
+Tools for PR interaction:
+- Post issue/PR comment: curl -X POST "https://$instance/api/v1/repos/$owner/$repo/issues/$number/comments" -H "Authorization: Bearer \$GITEA_TOKEN" -H "Content-Type: application/json" -d '{"body":"Your comment"}'
+- List PR comments: curl -s "https://$instance/api/v1/repos/$owner/$repo/issues/$number/comments" -H "Authorization: Bearer \$GITEA_TOKEN"
+- List PR reviews: curl -s "https://$instance/api/v1/repos/$owner/$repo/pulls/$number/reviews" -H "Authorization: Bearer \$GITEA_TOKEN"
+- Merge PR (only with approval): tea pr merge --repo $owner/$repo $number --style merge
+  - MERGING requires approval first! Check for: approval in reviews, OR "lgtm"/"approved" in comments
+  - If no approval, ask reviewer to approve first before merging
 
 Delegator's message:
 $user_message
 
-Work directory: $worktree_path (already on the fix branch)
+Work directory: $worktree_path
 EOF
     else
         cat <<EOF
@@ -304,6 +319,11 @@ Workflow:
 1. Read the issue at $instance/$owner/$repo/issues/$number AND all comments on that issue
 2. Check if a PR already exists for this issue
    - If PR exists and is open, review it and learn from it
+   - CRITICAL: Check if PR has merge conflicts before asking for review:
+     - Use: curl -s "https://$instance/api/v1/repos/$owner/$repo/pulls/$number" -H "Authorization: Bearer \$GITEA_TOKEN"
+     - If "mergeable": false, there ARE conflicts - you MUST resolve them FIRST
+     - To resolve: cd to worktree, git fetch origin, git rebase origin/main, resolve conflicts, git rebase --continue, git push --force-with-lease
+     - Only after resolving conflicts (mergeable: true) can you ask for review
    - If PR makes sense to continue, work on it instead
    - If PR is not worth continuing, create a new branch/PR but explain in PR description why you're creating a new one instead of continuing the existing PR
 3. Read README.md (if exists) to understand the general concept of this repository
@@ -475,6 +495,8 @@ cmd_continue() {
     
     if [ -z "$message" ]; then
         message=$(build_dev_agent_message "$issue_ref" "")
+    else
+        message=$(build_dev_agent_message "$issue_ref" "$message")
     fi
     
     local worktree_status=$(ensure_worktree "$issue_ref")