feat(functions): support auto-rebasing onto advanced push bookmarks in jj_check_conflicts

functions/jj_check_conflicts.fish

@@ -1,13 +1,48 @@
 function _jj_check_conflicts_usage
-    echo "Check if @- has been merged into a bookmark and auto rebase if needed.
+    echo "Check if @- has been merged/advanced and auto rebase the working copy if needed.
 Syntax: jj_check_conflicts [-h/--help] [bookmark]
 Args:
     -h/--help: Show the help doc.
-    bookmark: The target bookmark. If not specified, 'dev' is preferred, then 'main'."
+    bookmark: The target bookmark. If specified, @- is only checked against it
+        (manual override). If not specified: @- is checked against 'dev'
+        (preferred) then 'main'; if @- has merged there, the working copy is
+        rebased onto it. Otherwise, the auto-created push bookmark on @- (from
+        'jj git push --change @-') is followed forward when it has advanced."
 end
 
-function jj_check_conflicts --description 'Check if @- has been merged into a bookmark and auto rebase if needed'
+function _jj_check_conflicts_bookmark_exists --argument-names bookmark
+    jj log -r "$bookmark" --no-graph -T "" >/dev/null 2>&1
+end
+
+function _jj_check_conflicts_merged_into --argument-names bookmark
+    # Return 2 (and print an error) if the query fails; otherwise return 0 when
+    # @- is an ancestor of (i.e. has been merged into) $bookmark, 1 when not.
+    set -l merged_commits (jj log -r "@- & ::$bookmark" --no-graph -T "commit_id")
+    set -l log_status $status
+    if test $log_status -ne 0
+        echo (set_color $fish_color_error)"Error: Failed to query merge status of @- against "(set_color -o -i -u cyan)"$bookmark"(set_color normal)(set_color $fish_color_error)"."(set_color normal) >&2
+        return 2
+    end
+    test -n "$merged_commits"
+end
+
+function _jj_check_conflicts_warn_if_merged --argument-names bookmark
+    # Return 2 on query error, 0 when @- has merged into $bookmark (a warning is
+    # printed and the caller should rebase onto it), 1 when @- has not merged.
+    _jj_check_conflicts_merged_into "$bookmark"
+    set -l merged_status $status
+    if test $merged_status -eq 2
+        return 2
+    else if test $merged_status -eq 0
+        echo (set_color yellow)"Warning: @- has been merged into "(set_color -o -i -u cyan)"$bookmark"(set_color normal)(set_color yellow)". Auto-rebasing..."(set_color normal)
+        return 0
+    end
+    return 1
+end
+
+function jj_check_conflicts --description 'Check if @- has been merged/advanced and auto rebase if needed'
     argparse h/help -- $argv
+    or return 1
     if set -q _flag_help
         _jj_check_conflicts_usage
         return 0
@@ -25,23 +60,27 @@ function jj_check_conflicts --description 'Check if @- has been merged into a bo
         return $root_status
     end
 
-    set -l bookmark ""
+    # An explicit bookmark argument is used verbatim (manual override). Otherwise
+    # auto-detect a trunk bookmark ('dev' then 'main') and capture the auto-created
+    # push bookmark on @-. The push bookmark must be captured BEFORE the fetch,
+    # because the fetch may delete it (e.g. the PR was merged and its remote
+    # branch removed).
+    set -l explicit_bookmark ""
+    set -l push_bookmark ""
+
     if test (count $argv) -gt 0
-        set bookmark $argv[1]
-        jj log -r "$bookmark" --no-graph -T "" >/dev/null 2>&1
-        set -l bookmark_status $status
-        if test $bookmark_status -ne 0
-            echo (set_color $fish_color_error)"Error: Bookmark '"(set_color -o -i -u cyan)"$bookmark"(set_color normal)(set_color $fish_color_error)"' does not exist."(set_color normal) >&2
-            return $bookmark_status
+        set explicit_bookmark $argv[1]
+        if not _jj_check_conflicts_bookmark_exists "$explicit_bookmark"
+            echo (set_color $fish_color_error)"Error: Bookmark '"(set_color -o -i -u cyan)"$explicit_bookmark"(set_color normal)(set_color $fish_color_error)"' does not exist."(set_color normal) >&2
+            return 1
         end
     else
-        if jj log -r dev --no-graph -T "" >/dev/null 2>&1
-            set bookmark dev
-        else if jj log -r main --no-graph -T "" >/dev/null 2>&1
-            set bookmark main
-        else
-            echo (set_color $fish_color_error)"Error: Neither 'dev' nor 'main' bookmark exists. Please specify a bookmark name."(set_color normal) >&2
-            return 1
+        set -l prefix (jj config get git.push-bookmark-prefix 2>/dev/null)
+        test -n "$prefix"; or set prefix push-
+        set push_bookmark (jj log -r @- --no-graph -T 'local_bookmarks.map(|b| b.name()).join("\n")' | string match -- "$prefix*")
+        if test (count $push_bookmark) -gt 1
+            echo (set_color yellow)"Warning: Multiple push bookmarks on @- ("(string join ", " $push_bookmark)"); skipping push-bookmark tracking."(set_color normal) >&2
+            set push_bookmark ""
         end
     end
 
@@ -52,17 +91,68 @@ function jj_check_conflicts --description 'Check if @- has been merged into a bo
         return $fetch_status
     end
 
-    set -l merged_commits (jj log -r "@- & ::$bookmark" --no-graph -T "commit_id")
-    set -l log_status $status
-    if test $log_status -ne 0
-        echo (set_color $fish_color_error)"Error: Failed to query merge status of @- against "(set_color -o -i -u cyan)"$bookmark"(set_color normal)(set_color $fish_color_error)"."(set_color normal) >&2
-        return $log_status
-    end
-    if test -n "$merged_commits"
-        echo (set_color yellow)"Warning: @- has been merged into "(set_color -o -i -u cyan)"$bookmark"(set_color normal)(set_color yellow)". Auto-rebasing..."(set_color normal)
-        jj rebase --onto $bookmark
-    else
-        echo (set_color green)"@- is not merged into "(set_color -o -i -u cyan)"$bookmark"(set_color normal)(set_color green)". Safe to continue working on it."(set_color normal)
+    # Manual override: keep the original behaviour of checking @- against the
+    # given bookmark only.
+    if test -n "$explicit_bookmark"
+        _jj_check_conflicts_warn_if_merged "$explicit_bookmark"
+        set -l merged_status $status
+        if test $merged_status -eq 2
+            return 1
+        else if test $merged_status -eq 0
+            jj rebase --onto $explicit_bookmark
+            return $status
+        end
+        echo (set_color green)"@- is not merged into "(set_color -o -i -u cyan)"$explicit_bookmark"(set_color normal)(set_color green)". Safe to continue working on it."(set_color normal)
         echo
+        return 0
+    end
+
+    # Auto mode. Trunk wins: if @- has merged into dev/main, rebase onto it.
+    set -l trunk ""
+    if _jj_check_conflicts_bookmark_exists dev
+        set trunk dev
+    else if _jj_check_conflicts_bookmark_exists main
+        set trunk main
     end
+
+    if test -n "$trunk"
+        _jj_check_conflicts_warn_if_merged "$trunk"
+        set -l merged_status $status
+        if test $merged_status -eq 2
+            return 1
+        else if test $merged_status -eq 0
+            jj rebase --onto $trunk
+            return $status
+        end
+    end
+
+    # Not merged into trunk: follow the push bookmark forward when it has advanced
+    # to a strict descendant of @- (a safe fast-forward of our base).
+    if test -n "$push_bookmark"; and _jj_check_conflicts_bookmark_exists "$push_bookmark"
+        # A conflicted (divergent) bookmark resolves to multiple commits; rebasing
+        # onto its ambiguous name would fail, so warn and skip instead.
+        # The 'commit_id ++ "\n"' template is required, not redundant: with
+        # --no-graph jj does NOT separate revisions (the per-line newline comes
+        # from the graph renderer), so a bare 'commit_id' glues the ids together
+        # and the count below would always be 1.
+        set -l targets (jj log -r "$push_bookmark" --no-graph -T 'commit_id ++ "\n"')
+        if test (count $targets) -gt 1
+            echo (set_color yellow)"Warning: push bookmark "(set_color -o -i -u cyan)"$push_bookmark"(set_color normal)(set_color yellow)" is conflicted; skipping push-bookmark tracking."(set_color normal) >&2
+        else
+            set -l advanced (jj log -r "$push_bookmark & descendants(@-) & ~@-" --no-graph -T "commit_id")
+            if test -n "$advanced"
+                echo (set_color yellow)"Warning: push bookmark "(set_color -o -i -u cyan)"$push_bookmark"(set_color normal)(set_color yellow)" advanced past @-. Auto-rebasing onto it..."(set_color normal)
+                jj rebase --onto $push_bookmark
+                return $status
+            end
+        end
+    end
+
+    if test -z "$trunk"; and test -z "$push_bookmark"
+        echo (set_color $fish_color_error)"Error: Neither 'dev'/'main' nor a push bookmark on @- was found. Please specify a bookmark name."(set_color normal) >&2
+        return 1
+    end
+
+    echo (set_color green)"@- has not been merged/advanced and there is nothing to rebase onto. Safe to continue working on it."(set_color normal)
+    echo
 end