feat(commit-commands-jj): add ancestor check, post-merge cleanup, and absorbed change detection

plugins/commit-commands-jj/commands/finish.md

@@ -57,7 +57,19 @@ What would you like to do?
 
 ### Option 1: Push and create PR (most common)
 
-1. Ensure a bookmark exists on the target change:
+1. **Ancestor check before push.** Before creating the bookmark, check for non-empty changes between trunk and the target that are NOT the target itself:
+   ```bash
+   jj log -r 'ancestors(TARGET) & ~ancestors(trunk()) & ~TARGET' --no-graph
+   ```
+   If any exist, warn the user:
+   ```
+   This PR will include N ancestor change(s) not part of this work:
+   - <change-id>: <description>
+   They'll be merged into trunk with the PR.
+   ```
+   Let the user decide whether to squash them into the target first or push them separately.
+
+2. Ensure a bookmark exists on the target change:
    ```bash
    # Check for existing bookmark
    jj log -r <target> --no-graph -T 'bookmarks'
@@ -67,12 +79,12 @@ What would you like to do?
    jj bookmark create <kebab-case-name> -r <target>
    ```
 
-2. Push the bookmark:
+3. Push the bookmark:
    ```bash
    jj git push --bookmark <name> --allow-new
    ```
 
-3. Create the PR:
+4. Create the PR:
    ```bash
    gh pr create --title "<title>" --body "$(cat <<'EOF'
    ## Summary
@@ -86,9 +98,14 @@ What would you like to do?
    )"
    ```
 
-4. Output the PR URL.
+5. Output the PR URL.
+
+6. **Post-merge cleanup.** After a successful `gh pr merge`, before syncing, abandon all local changes that were ancestors of the PR branch (between trunk and the bookmark), since they're now in trunk via the squash-merge:
+   ```bash
+   jj abandon 'ancestors(TARGET) & ~ancestors(trunk())'
+   ```
 
-5. Then: Workspace cleanup (Step 4).
+7. Then: Workspace cleanup (Step 4).
 
 ### Option 2: Squash into trunk (local merge)
 

plugins/commit-commands-jj/commands/sync.md

@@ -25,7 +25,17 @@ description: Fetch from remote and rebase the current change onto trunk
 Sync fetches the latest remote state and rebases your current work onto trunk. This is the jj equivalent of `git pull --rebase`.
 
 1. Fetch from the remote: `jj git fetch`
-2. Rebase onto trunk: `jj rebase -d main@origin`
+2. **Detect absorbed changes.** Before rebasing, check for non-empty local changes above the old trunk that may already be included in a squash-merged PR:
+   ```bash
+   jj log -r 'ancestors(@) & ~ancestors(trunk()) & ~@' --no-graph
+   ```
+   If any exist and would conflict when rebased onto the new trunk, list them and offer to abandon rather than forcing a rebase that produces conflicts:
+   ```
+   These N change(s) appear to be absorbed by a squash-merge now in trunk:
+   - <change-id>: <description>
+   Abandon them? (They're already in trunk via the PR merge.)
+   ```
+3. Rebase onto trunk: `jj rebase -d main@origin`
    - If that fails (e.g., remote is not named `origin` or branch is not `main`), fall back to `jj rebase -d trunk()`
 3. Check for conflicts: `jj log -r 'conflicts()' --no-graph -T 'json(self) ++ "\n"'`
    - If conflicts exist, report them clearly so the user can resolve them