docs(workflow): require rebase-first + rebase-and-merge policy

scripts/openclaw-upstream-workflow.md

@@ -13,7 +13,7 @@ Use this whenever modifying OpenClaw itself.
 cd external/openclaw-upstream
 git fetch --all --prune
 git checkout main
-git pull --ff-only
+git pull --rebase
 git checkout -b fix/<short-topic>
 ```
 
@@ -21,7 +21,14 @@ Then:
 1. Implement in `src/` (and docs/tests as needed).
 2. Run targeted tests first; run broader suite if change touches shared paths.
 3. Commit with Conventional Commit format.
-4. Push branch and open PR.
+4. Rebase onto latest `main` before push/PR:
+   - `git fetch origin && git rebase origin/main`
+5. Push branch and open PR.
+
+## Merge policy
+
+- Preferred PR strategy: **Rebase and merge**
+- Avoid merge commits unless explicitly required for a special case
 
 ## Branch naming
 
@@ -42,7 +49,7 @@ scripts/openclaw-update-safe.sh
 - After runtime update, re-sync upstream clone before new changes:
 
 ```bash
-cd external/openclaw-upstream && git fetch --all --prune && git checkout main && git pull --ff-only
+cd external/openclaw-upstream && git fetch --all --prune && git checkout main && git pull --rebase
 ```
 
 ## Emergency dist hotfix policy