From 548862c3e3d96d3095d3f471df4b15fd20540fb1 Mon Sep 17 00:00:00 2001
From: Felipe Coutinho <felipe_coutinho@id.uff.br>
Date: Tue, 19 May 2026 11:54:35 -0300
Subject: [PATCH 1/4] Implement branches

Fix freeze
---
 pyproject.toml                                |   1 +
 src/noworkflow/now/cmd/__init__.py            |   4 +
 src/noworkflow/now/cmd/cmd_branch.py          |  72 ++++++
 src/noworkflow/now/cmd/cmd_restore.py         |   5 +-
 src/noworkflow/now/cmd/cmd_run.py             |   6 +-
 .../now/persistence/content/base.py           |   2 +-
 .../now/persistence/content/dulwich_engine.py | 229 +++++++++++++++++-
 .../now/persistence/content/gitbase.py        |   4 +-
 .../now/persistence/content/parallel.py       |  22 +-
 .../now/persistence/content/plain_engine.py   |   2 +-
 .../now/persistence/models/trial.py           |  27 ++-
 11 files changed, 356 insertions(+), 18 deletions(-)
 create mode 100644 src/noworkflow/now/cmd/cmd_branch.py

diff --git a/pyproject.toml b/pyproject.toml
index f2b1de92..248b4d44 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -39,6 +39,7 @@ dependencies = [
     "setuptools<72",
     "nbformat",
     "graphviz",
+    "dulwich"
 ]
 
 [project.optional-dependencies]
diff --git a/src/noworkflow/now/cmd/__init__.py b/src/noworkflow/now/cmd/__init__.py
index a561982e..e13a2765 100644
--- a/src/noworkflow/now/cmd/__init__.py
+++ b/src/noworkflow/now/cmd/__init__.py
@@ -29,6 +29,7 @@
 from .cmd_gc import GC
 from .cmd_evaluation import Evaluation
 from .cmd_clean import Clean
+from .cmd_branch import Branch
 from ..utils.io import print_msg
 
 
@@ -59,7 +60,9 @@ def main():
         GC(),
         Evaluation(),
         Clean(),
+        Branch()
     ]
+
     for cmd in commands:
         cmd.create_parser(subparsers)
 
@@ -95,4 +98,5 @@ def main():
     "Push",
     "Pull",
     "Import",
+    "Branch",
 ]
diff --git a/src/noworkflow/now/cmd/cmd_branch.py b/src/noworkflow/now/cmd/cmd_branch.py
new file mode 100644
index 00000000..8c9f72e0
--- /dev/null
+++ b/src/noworkflow/now/cmd/cmd_branch.py
@@ -0,0 +1,72 @@
+# Copyright (c) 2026 Universidade Federal Fluminense (UFF)
+# This file is part of noWorkflow.
+# Please, consult the license terms in the LICENSE file.
+"""'now branch' command"""
+from __future__ import (absolute_import, print_function,
+                        division, unicode_literals)
+
+import os
+
+from ..persistence import persistence_config, content
+from ..persistence.models import Trial
+from ..utils.io import print_msg
+
+from .command import Command
+
+
+class Branch(Command):
+    """Manage noWorkflow Git branches"""
+
+    def add_arguments(self):
+        add_arg = self.add_argument
+        add_arg("--dir", type=str,
+                help="set project path where is the database. Default to "
+                     "current directory")
+        add_arg("--content-engine", type=str,
+                help="set the content database engine")
+
+        subparsers = self.parser.add_subparsers(dest="branch_cmd")
+
+        subparsers.add_parser("list", help="list branches")
+        subparsers.add_parser("current", help="show current branch")
+
+        switch = subparsers.add_parser("switch", help="switch branch")
+        switch.add_argument("name", type=str)
+
+        rename = subparsers.add_parser("rename", help="rename branch")
+        rename.add_argument("old", type=str)
+        rename.add_argument("new", type=str)
+
+    def _connect(self, args):
+        persistence_config.content_engine = args.content_engine
+        persistence_config.connect_existing(args.dir or os.getcwd())
+        if not hasattr(content.content_database_engine, "branches"):
+            raise RuntimeError(
+                "Git branch prototype requires a Git content engine"
+            )
+
+    def execute(self, args):
+        self._connect(args)
+        command = args.branch_cmd or "list"
+
+        if command == "list":
+            current = content.current_branch()
+            for name in content.branches():
+                marker = "*" if name == current else " "
+                trial_id = content.branch_trial(name) or "<no trial>"
+                print("{} {} {}".format(marker, name, trial_id))
+        elif command == "current":
+            trial_id = content.current_branch_trial() or "<no trial>"
+            print("{} {}".format(content.current_branch(), trial_id))
+        elif command == "switch":
+            content.checkout_branch(args.name)
+            trial_id = content.branch_trial(args.name)
+            if trial_id:
+                Trial(trial_id).create_head()
+            print_msg("Switched to branch {}".format(args.name), True)
+        elif command == "rename":
+            content.rename_branch(args.old, args.new)
+            print_msg(
+                "Renamed branch {} to {}".format(args.old, args.new),
+                True
+            )
diff --git a/src/noworkflow/now/cmd/cmd_restore.py b/src/noworkflow/now/cmd/cmd_restore.py
index a1b1e472..cc4cc829 100644
--- a/src/noworkflow/now/cmd/cmd_restore.py
+++ b/src/noworkflow/now/cmd/cmd_restore.py
@@ -126,7 +126,10 @@ def create_backup(self, metascript, files, args):
 
         print_msg("Backup Trial {} created".format(metascript.trial_id),
                   self.print_msg)
-        content.commit_content(metascript.message or "Backup Trial {}".format(metascript.trial_id))
+        content.commit_content(
+            metascript.message or "Backup Trial {}".format(metascript.trial_id),
+            trial_id=metascript.trial_id
+        )
 
     def restore(self, path, code_hash, trial_id, mode="normal"):
         """Restore file with <code_hash> from <trial_id>"""
diff --git a/src/noworkflow/now/cmd/cmd_run.py b/src/noworkflow/now/cmd/cmd_run.py
index 0d827c95..d7bd4dde 100644
--- a/src/noworkflow/now/cmd/cmd_run.py
+++ b/src/noworkflow/now/cmd/cmd_run.py
@@ -67,9 +67,13 @@ def run(metascript, args=None):
         Tag.create_automatic_tag(*metascript.create_automatic_tag_args())
         Trial.set_user_based_on_env(metascript.trial_id)
         metaprofiler.meta_profiler.save()
-        content.commit_content(metascript.message or "Trial {}".format(metascript.trial_id))
+        content.commit_content(
+            metascript.message or "Trial {}".format(metascript.trial_id),
+            trial_id=metascript.trial_id
+        )
     finally:
         metascript.create_last()
+        content.close()
 
 class Run(Command):
     """Run a script collecting its provenance"""
diff --git a/src/noworkflow/now/persistence/content/base.py b/src/noworkflow/now/persistence/content/base.py
index a14a8cee..403f6426 100644
--- a/src/noworkflow/now/persistence/content/base.py
+++ b/src/noworkflow/now/persistence/content/base.py
@@ -60,7 +60,7 @@ def gc(self, content_hash):
         """Collect garbage from database"""
         raise NotImplementedError("Implement in subclass")
 
-    def commit_content(self, message):
+    def commit_content(self, message, trial_id=None):
         """Commit content"""
         raise NotImplementedError("Implement in subclass")
 
diff --git a/src/noworkflow/now/persistence/content/dulwich_engine.py b/src/noworkflow/now/persistence/content/dulwich_engine.py
index fe13a108..4e8c7cd8 100644
--- a/src/noworkflow/now/persistence/content/dulwich_engine.py
+++ b/src/noworkflow/now/persistence/content/dulwich_engine.py
@@ -2,6 +2,7 @@
 import hashlib
 import time
 import io
+import posixpath
 
 from dulwich import file
 from dulwich.repo import Repo
@@ -29,9 +30,12 @@ def connect(self, config):
             os.makedirs(self.content_path)
             Repo.init_bare(self.content_path)
             self.repo = Repo(self.content_path)
+            self._commit_ref = self.branch_ref(self._default_branch)
+            self._set_head(self._commit_ref)
             self.create_initial_commit()
         else:
             self.repo = Repo(self.content_path)
+            self._commit_ref = self._current_branch_ref()
 
     @staticmethod
     def do_put(content_path, object_hashes, lock, content, filename):
@@ -81,12 +85,12 @@ def create_initial_commit(self):
             object_store.add_object(empty_tree)
             self.create_commit_object(self._initial_message, empty_tree.id)
 
-    def create_commit_object(self, message, tree):
+    def create_commit_object(self, message, tree, trial_id=None):
         """Create a commit object"""
         with self.use_safe_open(): 
-            master_ref = self.repo.get_refs().get(
-                self._commit_ref.encode("utf-8"), None
-            )
+            self._commit_ref = self._current_branch_ref()
+            branch_ref = self._commit_ref.encode("utf-8")
+            master_ref = self.repo.get_refs().get(branch_ref, None)
             
             commit = Commit()
             if master_ref is not None:
@@ -102,12 +106,19 @@ def create_commit_object(self, message, tree):
             commit.message = message.encode()
 
             self.repo.object_store.add_object(commit)
-            self.repo.refs[
-                self._commit_ref.encode("utf-8")
-            ] = commit.id
+            self.repo.refs[branch_ref] = commit.id
+            if trial_id:
+                self.repo.refs[self.trial_ref(trial_id).encode("utf-8")] = commit.id
 
             return commit.id
 
+    def commit_content(self, message, trial_id=None):
+        """Commit the current files and update branch/trial refs"""
+        commit_id = super(DulwichEngine, self).commit_content(message)
+        if trial_id:
+            self.repo.refs[self.trial_ref(trial_id).encode("utf-8")] = commit_id
+        return commit_id
+
     def new_tree(self, parent):
         """Create new git tree"""
         return Tree()
@@ -126,6 +137,210 @@ def write_tree(self, tree):
             self.repo.object_store.add_object(tree)
             return tree.id
 
+    # Branch prototype API
+
+    @staticmethod
+    def _to_text(value):
+        if value is None:
+            return None
+        if isinstance(value, bytes):
+            return value.decode("utf-8")
+        return value
+
+    @staticmethod
+    def _to_hex(value):
+        if value is None:
+            return None
+        if isinstance(value, bytes):
+            return value.decode("ascii")
+        return str(value)
+
+    @staticmethod
+    def _valid_branch_name(name):
+        return (
+            name and
+            ".." not in name and
+            not name.startswith("/") and
+            not name.endswith("/") and
+            not name.endswith(".lock") and
+            all(ch not in name for ch in " ~^:?*[\\")
+        )
+
+    def branch_ref(self, name):
+        """Return a full Git branch ref"""
+        if not self._valid_branch_name(name):
+            raise RuntimeError("invalid branch name: {}".format(name))
+        return "refs/heads/{}".format(name)
+
+    def trial_ref(self, trial_id):
+        """Return a full noWorkflow trial ref"""
+        return self._trial_ref_prefix + str(trial_id)
+
+    def _set_head(self, branch_ref):
+        """Point HEAD at a branch ref"""
+        ref = branch_ref.encode("utf-8")
+        try:
+            self.repo.refs.set_symbolic_ref(b"HEAD", ref)
+        except AttributeError:
+            with open(os.path.join(self.content_path, "HEAD"), "wb") as fil:
+                fil.write(b"ref: " + ref + b"\n")
+        self._commit_ref = branch_ref
+
+    def _current_branch_ref(self):
+        """Return current branch ref, upgrading old stores lazily"""
+        try:
+            head = self.repo.refs.read_ref(b"HEAD")
+        except (AttributeError, KeyError):
+            head = None
+        head = self._to_text(head)
+        if head and head.startswith("refs/heads/"):
+            return head
+
+        refs = self.repo.get_refs()
+        for candidate in ("refs/heads/master", "refs/heads/main"):
+            if candidate.encode("utf-8") in refs:
+                self._set_head(candidate)
+                return candidate
+
+        branch_ref = self.branch_ref(self._default_branch)
+        self._set_head(branch_ref)
+        return branch_ref
+
+    def current_branch(self):
+        """Return the current branch name"""
+        ref = self._current_branch_ref()
+        return ref.rsplit("/", 1)[-1]
+
+    def branches(self):
+        """Return branch names in content.git"""
+        result = []
+        for ref in self.repo.get_refs():
+            ref = self._to_text(ref)
+            if ref.startswith("refs/heads/"):
+                result.append(ref.rsplit("/", 1)[-1])
+        return sorted(result)
+
+    def branch_commit(self, name=None):
+        """Return commit id for a branch"""
+        branch_ref = self.branch_ref(name) if name else self._current_branch_ref()
+        commit_id = self.repo.get_refs().get(branch_ref.encode("utf-8"))
+        return self._to_hex(commit_id)
+
+    def trial_commit(self, trial_id):
+        """Return commit id for a trial ref"""
+        commit_id = self.repo.get_refs().get(self.trial_ref(trial_id).encode("utf-8"))
+        print(commit_id)
+        return self._to_hex(commit_id)
+
+    def trial_for_commit(self, commit_id):
+        """Find trial id by commit id"""
+        if not commit_id:
+            return None
+        wanted = self._to_hex(commit_id)
+        prefix = self._trial_ref_prefix
+        for ref, value in self.repo.get_refs().items():
+            ref = self._to_text(ref)
+            if ref.startswith(prefix) and self._to_hex(value) == wanted:
+                return ref[len(prefix):]
+        return None
+
+    def current_branch_head(self):
+        """Return trial id at the current branch head"""
+        return self.trial_for_commit(self.branch_commit())
+
+    def branch_trial(self, name):
+        """Return trial id at the named branch head"""
+        return self.trial_for_commit(self.branch_commit(name))
+
+    def create_branch(self, name, commit_id):
+        """Create branch pointing to commit id"""
+        if not commit_id:
+            raise RuntimeError("cannot create branch without a commit")
+        branch_ref = self.branch_ref(name)
+        encoded_ref = branch_ref.encode("utf-8")
+        if encoded_ref in self.repo.get_refs():
+            raise RuntimeError("branch already exists: {}".format(name))
+        self.repo.refs[encoded_ref] = commit_id.encode("ascii")
+
+    def switch_branch(self, name):
+        """Switch HEAD to branch"""
+        branch_ref = self.branch_ref(name)
+        if branch_ref.encode("utf-8") not in self.repo.get_refs():
+            raise RuntimeError("branch not found: {}".format(name))
+        self._set_head(branch_ref)
+
+    def rename_branch(self, old, new):
+        """Rename a branch ref"""
+        old_ref = self.branch_ref(old)
+        new_ref = self.branch_ref(new)
+        refs = self.repo.get_refs()
+        old_key = old_ref.encode("utf-8")
+        new_key = new_ref.encode("utf-8")
+        if old_key not in refs:
+            raise RuntimeError("branch not found: {}".format(old))
+        if new_key in refs:
+            raise RuntimeError("branch already exists: {}".format(new))
+        self.repo.refs[new_key] = refs[old_key]
+        del self.repo.refs[old_key]
+        if self._current_branch_ref() == old_ref:
+            self._set_head(new_ref)
+
+    def ensure_branch_for_trial(self, trial_id):
+        """Create and switch to an automatic branch for a restored trial"""
+        current_trial = self.current_branch_trial()
+        if current_trial == str(trial_id):
+            return self.current_branch()
+
+        commit_id = self.trial_commit(trial_id)
+        if not commit_id:
+            return self.current_branch()
+
+        base = "now-diverge-{}".format(str(trial_id)[:8])
+        name = base
+        index = 1
+        existing = set(self.branches())
+        while name in existing:
+            index += 1
+            name = "{}-{}".format(base, index)
+        self.create_branch(name, commit_id)
+        self.switch_branch(name)
+        return name
+
+    def checkout_branch(self, name):
+        """Switch branch and restore versioned files from its tree"""
+        self.switch_branch(name)
+        commit_id = self.branch_commit(name)
+        if not commit_id:
+            return
+        commit = self.repo[commit_id.encode("ascii")]
+        self._checkout_tree(commit.tree, "")
+
+    def _tree_items(self, tree):
+        if hasattr(tree, "iteritems"):
+            return tree.iteritems()
+        return tree.items()
+
+    def _checkout_tree(self, tree_id, prefix):
+        tree = self.repo[tree_id]
+        for item in self._tree_items(tree):
+            if len(item) == 3:
+                name, mode, sha = item
+            else:
+                name, entry = item
+                mode, sha = entry.mode, entry.sha
+            name = self._to_text(name)
+            relative = posixpath.join(prefix, name) if prefix else name
+            obj = self.repo[sha]
+            if isinstance(obj, Tree):
+                self._checkout_tree(sha, relative)
+            else:
+                path = os.path.join(self.base_path, *relative.split("/"))
+                parent = os.path.dirname(path)
+                if parent:
+                    os.makedirs(parent, exist_ok=True)
+                with self.std_open(path, "wb") as fil:
+                    fil.write(obj.as_raw_string())
+
 
 DistributedDulwichEngine = create_distributed(DulwichEngine)
 PoolDulwichEngine = create_pool(DulwichEngine)
diff --git a/src/noworkflow/now/persistence/content/gitbase.py b/src/noworkflow/now/persistence/content/gitbase.py
index eb224d04..54fbb4b4 100644
--- a/src/noworkflow/now/persistence/content/gitbase.py
+++ b/src/noworkflow/now/persistence/content/gitbase.py
@@ -17,6 +17,8 @@ def __init__(self, config):
         self._commit_name = 'Noworkflow'
         self._commit_email = 'noworkflow@noworkflow.com'
         self._commit_ref = 'refs/heads/master'
+        self._default_branch = 'main'
+        self._trial_ref_prefix = 'refs/noworkflow/trials/'
         self._initial_message = "Initial Commit"
         self.name_counter = Counter()
         self.base_path = None
@@ -32,7 +34,7 @@ def set_path(self, config):
     def gc(self, aggressive=False):
         git_system.garbage_collection(self.content_path, aggressive)
 
-    def commit_content(self, message):
+    def commit_content(self, message, trial_id=None):
         """Commit the current files of content database"""
         self.close()
         trees = {'': self.new_tree('')}
diff --git a/src/noworkflow/now/persistence/content/parallel.py b/src/noworkflow/now/persistence/content/parallel.py
index 61b1579c..5d76b31e 100644
--- a/src/noworkflow/now/persistence/content/parallel.py
+++ b/src/noworkflow/now/persistence/content/parallel.py
@@ -24,8 +24,10 @@ def run(self):
                     self.task_queue.task_done()
                     break
 
-                self.engine.do_put(*queue_content)
-                self.task_queue.task_done()
+                try:
+                    self.engine.do_put(*queue_content)
+                finally:
+                    self.task_queue.task_done()
 
 
     class Distributed(cls):
@@ -50,6 +52,7 @@ def start_processes(self):
             with safeopen.use_safe_open():
                 for _ in range(self.num_consumers):
                     consumer = Worker(self.tasks, self)
+                    consumer.daemon = True
                     self.consumers.append(consumer)
                     consumer.start()
 
@@ -69,9 +72,18 @@ def close(self):
                 for _ in range(self.num_consumers):
                     self.tasks.put(None)
 
-                # Wait for all of the tasks to finish
-                self.tasks.join()
-                self.processes_started = False
+                try:
+                    # Wait for all of the tasks to finish
+                    self.tasks.join()
+                    for consumer in self.consumers:
+                        consumer.join()
+                finally:
+                    for consumer in self.consumers:
+                        if consumer.is_alive():
+                            consumer.terminate()
+                            consumer.join()
+                    self.consumers = []
+                    self.processes_started = False
         
     Distributed.__name__ = name or ("Distributed" + cls.__name__)
     return Distributed
diff --git a/src/noworkflow/now/persistence/content/plain_engine.py b/src/noworkflow/now/persistence/content/plain_engine.py
index a7e0143e..544abd9a 100644
--- a/src/noworkflow/now/persistence/content/plain_engine.py
+++ b/src/noworkflow/now/persistence/content/plain_engine.py
@@ -68,7 +68,7 @@ def gc(self, content_hash):
         """Do nothing for plain storage"""
         pass
 
-    def commit_content(self, message):
+    def commit_content(self, message, trial_id=None):
         """Do nothing for plain storage"""
         pass
 
diff --git a/src/noworkflow/now/persistence/models/trial.py b/src/noworkflow/now/persistence/models/trial.py
index 1d021121..f86ecf3e 100644
--- a/src/noworkflow/now/persistence/models/trial.py
+++ b/src/noworkflow/now/persistence/models/trial.py
@@ -1062,6 +1062,31 @@ def load_parent(cls, script, remove=True, check=False, session=None):
                 session=session)
         return proxy(trial)
 
+    @classmethod
+    def load_branch_parent(cls, script, session=None):
+        """Load parent from Git branch metadata, falling back to Head/last trial"""
+        session = session or relational.session
+        head = Head.load_head(script, session=session)
+        if head:
+            trial = head.trial
+            try:
+                content.ensure_branch_for_trial(trial.id)
+            except AttributeError:
+                pass
+            Head.remove(head.id, session=relational.make_session())
+            return trial
+
+        try:
+            trial_id = content.current_branch_trial()
+        except AttributeError:
+            trial_id = None
+        if trial_id:
+            trial = cls.load_trial(trial_id, session=session)
+            if trial:
+                return proxy(trial)
+
+        return proxy(cls.last_trial(script=script, check=True, session=session))
+
     @classmethod  # query
     def fast_last_trial_id(cls, session=None):
         """Load last trial id that did not bypass modules
@@ -1228,7 +1253,7 @@ def create(cls, script, start, command, path, bypass_modules, session=None):
         session = session or relational.session
 
         # ToDo: use core query
-        parent = cls.load_parent(script, check=True)
+        parent = cls.load_branch_parent(script, session=session)
         parent_id = parent.id if parent else None
 
         inherited_id = None

From b8f518c6eb303e2d6d32b1501a28077aaa2e319a Mon Sep 17 00:00:00 2001
From: Felipe Coutinho <felipe_coutinho@id.uff.br>
Date: Thu, 21 May 2026 17:21:16 -0300
Subject: [PATCH 2/4] Refactor

---
 src/noworkflow/now/cmd/cmd_branch.py          |  5 +--
 .../now/persistence/content/dulwich_engine.py | 44 ++++++++-----------
 .../now/persistence/content/gitbase.py        |  2 +-
 .../now/persistence/models/trial.py           | 36 +++------------
 4 files changed, 28 insertions(+), 59 deletions(-)

diff --git a/src/noworkflow/now/cmd/cmd_branch.py b/src/noworkflow/now/cmd/cmd_branch.py
index 8c9f72e0..c459ed95 100644
--- a/src/noworkflow/now/cmd/cmd_branch.py
+++ b/src/noworkflow/now/cmd/cmd_branch.py
@@ -66,7 +66,4 @@ def execute(self, args):
             print_msg("Switched to branch {}".format(args.name), True)
         elif command == "rename":
             content.rename_branch(args.old, args.new)
-            print_msg(
-                "Renamed branch {} to {}".format(args.old, args.new),
-                True
-            )
+            print_msg("Renamed branch {} to {}".format(args.old, args.new), True)
diff --git a/src/noworkflow/now/persistence/content/dulwich_engine.py b/src/noworkflow/now/persistence/content/dulwich_engine.py
index 4e8c7cd8..6db53eba 100644
--- a/src/noworkflow/now/persistence/content/dulwich_engine.py
+++ b/src/noworkflow/now/persistence/content/dulwich_engine.py
@@ -192,13 +192,13 @@ def _current_branch_ref(self):
             head = self.repo.refs.read_ref(b"HEAD")
         except (AttributeError, KeyError):
             head = None
-        head = self._to_text(head)
+        head = head.decode("utf-8")
         if head and head.startswith("refs/heads/"):
             return head
 
         refs = self.repo.get_refs()
         for candidate in ("refs/heads/master", "refs/heads/main"):
-            if candidate.encode("utf-8") in refs:
+            if candidate in refs:
                 self._set_head(candidate)
                 return candidate
 
@@ -215,24 +215,16 @@ def branches(self):
         """Return branch names in content.git"""
         result = []
         for ref in self.repo.get_refs():
-            ref = self._to_text(ref)
             if ref.startswith("refs/heads/"):
                 result.append(ref.rsplit("/", 1)[-1])
         return sorted(result)
 
-    def branch_commit(self, name=None):
-        """Return commit id for a branch"""
-        branch_ref = self.branch_ref(name) if name else self._current_branch_ref()
-        commit_id = self.repo.get_refs().get(branch_ref.encode("utf-8"))
-        return self._to_hex(commit_id)
 
-    def trial_commit(self, trial_id):
+    def get_commit_id_by_trial_id(self, trial_id):
         """Return commit id for a trial ref"""
-        commit_id = self.repo.get_refs().get(self.trial_ref(trial_id).encode("utf-8"))
-        print(commit_id)
-        return self._to_hex(commit_id)
+        return self.repo.get_refs().get(self.trial_ref(trial_id).encode("utf-8"))
 
-    def trial_for_commit(self, commit_id):
+    def get_trial_id_by_commit_id(self, commit_id):
         """Find trial id by commit id"""
         if not commit_id:
             return None
@@ -240,32 +232,35 @@ def trial_for_commit(self, commit_id):
         prefix = self._trial_ref_prefix
         for ref, value in self.repo.get_refs().items():
             ref = self._to_text(ref)
-            if ref.startswith(prefix) and self._to_hex(value) == wanted:
+            if ref.startswith(prefix) and value == commit_id:
                 return ref[len(prefix):]
         return None
 
-    def current_branch_head(self):
-        """Return trial id at the current branch head"""
-        return self.trial_for_commit(self.branch_commit())
+    def get_branch_head_trial_id(self, name=None):
+        """Return trial_id at the named branch head"""
+        """If no name is given, return trial_id current branch head"""
+        return self.get_trial_id_by_commit_id(self.get_branch_head_commit_id(name))
 
-    def branch_trial(self, name):
-        """Return trial id at the named branch head"""
-        return self.trial_for_commit(self.branch_commit(name))
+    def get_branch_head_commit_id(self, name=None):
+        """Return commit_id at the named branch head"""
+        """If no name is given, return commit_id current branch head"""
+        branch_ref = self.branch_ref(name) if name else self._current_branch_ref()
+        commit_id = self.repo.get_refs().get(branch_ref.encode("utf-8"))
+        return commit_id
 
     def create_branch(self, name, commit_id):
         """Create branch pointing to commit id"""
         if not commit_id:
             raise RuntimeError("cannot create branch without a commit")
         branch_ref = self.branch_ref(name)
-        encoded_ref = branch_ref.encode("utf-8")
-        if encoded_ref in self.repo.get_refs():
+        if branch_ref in self.repo.get_refs():
             raise RuntimeError("branch already exists: {}".format(name))
-        self.repo.refs[encoded_ref] = commit_id.encode("ascii")
+        self.repo.refs[branch_ref] = commit_id.encode("ascii")
 
     def switch_branch(self, name):
         """Switch HEAD to branch"""
         branch_ref = self.branch_ref(name)
-        if branch_ref.encode("utf-8") not in self.repo.get_refs():
+        if branch_ref not in self.repo.get_refs():
             raise RuntimeError("branch not found: {}".format(name))
         self._set_head(branch_ref)
 
@@ -328,7 +323,6 @@ def _checkout_tree(self, tree_id, prefix):
             else:
                 name, entry = item
                 mode, sha = entry.mode, entry.sha
-            name = self._to_text(name)
             relative = posixpath.join(prefix, name) if prefix else name
             obj = self.repo[sha]
             if isinstance(obj, Tree):
diff --git a/src/noworkflow/now/persistence/content/gitbase.py b/src/noworkflow/now/persistence/content/gitbase.py
index 54fbb4b4..8e34fc11 100644
--- a/src/noworkflow/now/persistence/content/gitbase.py
+++ b/src/noworkflow/now/persistence/content/gitbase.py
@@ -17,7 +17,7 @@ def __init__(self, config):
         self._commit_name = 'Noworkflow'
         self._commit_email = 'noworkflow@noworkflow.com'
         self._commit_ref = 'refs/heads/master'
-        self._default_branch = 'main'
+        self._default_branch = 'master'
         self._trial_ref_prefix = 'refs/noworkflow/trials/'
         self._initial_message = "Initial Commit"
         self.name_counter = Counter()
diff --git a/src/noworkflow/now/persistence/models/trial.py b/src/noworkflow/now/persistence/models/trial.py
index f86ecf3e..a62a563d 100644
--- a/src/noworkflow/now/persistence/models/trial.py
+++ b/src/noworkflow/now/persistence/models/trial.py
@@ -1052,40 +1052,18 @@ def load_parent(cls, script, remove=True, check=False, session=None):
         """
         session = session or relational.session
         head = Head.load_head(script, session=session)
+
         if head:
+            content.ensure_branch_for_trial(head.trial.id)
             trial = head.trial
             if remove:
                 Head.remove(head.id, session=relational.make_session())
-        elif not head:
-            trial = cls.last_trial(
-                script=script, check=check,
-                session=session)
-        return proxy(trial)
-
-    @classmethod
-    def load_branch_parent(cls, script, session=None):
-        """Load parent from Git branch metadata, falling back to Head/last trial"""
-        session = session or relational.session
-        head = Head.load_head(script, session=session)
-        if head:
-            trial = head.trial
-            try:
-                content.ensure_branch_for_trial(trial.id)
-            except AttributeError:
-                pass
-            Head.remove(head.id, session=relational.make_session())
-            return trial
+            return proxy(trial)
 
-        try:
-            trial_id = content.current_branch_trial()
-        except AttributeError:
-            trial_id = None
-        if trial_id:
-            trial = cls.load_trial(trial_id, session=session)
-            if trial:
-                return proxy(trial)
+        trial_id = content.get_branch_head_trial_id()
+        trial = cls.load_trial(trial_id, session=session)
+        return proxy(trial)
 
-        return proxy(cls.last_trial(script=script, check=True, session=session))
 
     @classmethod  # query
     def fast_last_trial_id(cls, session=None):
@@ -1253,7 +1231,7 @@ def create(cls, script, start, command, path, bypass_modules, session=None):
         session = session or relational.session
 
         # ToDo: use core query
-        parent = cls.load_branch_parent(script, session=session)
+        parent = cls.load_parent(script, check=True)
         parent_id = parent.id if parent else None
 
         inherited_id = None

From 24c30a6fea3a13341412af80b9bc488fd4d13520 Mon Sep 17 00:00:00 2001
From: Felipe Coutinho <felipe_coutinho@id.uff.br>
Date: Mon, 1 Jun 2026 15:42:24 -0300
Subject: [PATCH 3/4] Fix implementation

---
 src/noworkflow/now/cmd/cmd_run.py             |   3 +-
 .../now/persistence/content/dulwich_engine.py | 247 +++++++-----------
 .../now/persistence/content/gitbase.py        |   2 +
 3 files changed, 102 insertions(+), 150 deletions(-)

diff --git a/src/noworkflow/now/cmd/cmd_run.py b/src/noworkflow/now/cmd/cmd_run.py
index d7bd4dde..6c9bf547 100644
--- a/src/noworkflow/now/cmd/cmd_run.py
+++ b/src/noworkflow/now/cmd/cmd_run.py
@@ -67,6 +67,7 @@ def run(metascript, args=None):
         Tag.create_automatic_tag(*metascript.create_automatic_tag_args())
         Trial.set_user_based_on_env(metascript.trial_id)
         metaprofiler.meta_profiler.save()
+
         content.commit_content(
             metascript.message or "Trial {}".format(metascript.trial_id),
             trial_id=metascript.trial_id
@@ -159,7 +160,7 @@ def add_arguments(self):
                 help="add a message to the commit of the trial")
         add_arg("--content-engine", type=str,
                 help="set the content database engine")
-                                
+
 
         # Internal
         add_cmd("--create_last", action="store_true", help=argparse.SUPPRESS)
diff --git a/src/noworkflow/now/persistence/content/dulwich_engine.py b/src/noworkflow/now/persistence/content/dulwich_engine.py
index 6db53eba..955c8d6c 100644
--- a/src/noworkflow/now/persistence/content/dulwich_engine.py
+++ b/src/noworkflow/now/persistence/content/dulwich_engine.py
@@ -15,6 +15,7 @@
 from .gitbase import GitContentDatabaseEngine
 from .parallel import create_distributed, create_pool, create_threading, NullLock
 from . import safeopen
+from ..models import Trial
 
 class DulwichEngine(GitContentDatabaseEngine):
 
@@ -83,18 +84,30 @@ def create_initial_commit(self):
             object_store = self.repo.object_store
             empty_tree = Tree()
             object_store.add_object(empty_tree)
-            self.create_commit_object(self._initial_message, empty_tree.id)
+            commit_id = self.create_commit_object(self._initial_message, empty_tree.id)
+            self.repo.refs[(self._commit_ref).encode("utf-8")] = commit_id
+            self.switch_branch(self._default_branch)
 
     def create_commit_object(self, message, tree, trial_id=None):
         """Create a commit object"""
         with self.use_safe_open(): 
-            self._commit_ref = self._current_branch_ref()
-            branch_ref = self._commit_ref.encode("utf-8")
-            master_ref = self.repo.get_refs().get(branch_ref, None)
-            
             commit = Commit()
-            if master_ref is not None:
-                commit.parents = [master_ref]
+
+            if trial_id != None:
+                current_branch, current_branch_ref = self.current_branch()
+                branch_head_commit_id = self.get_branch_head_commit_id(current_branch)
+                branch_head_trial_id = self.get_branch_head_trial_id(current_branch)
+
+                parent_trial_id = Trial(trial_id).parent_id
+
+                if parent_trial_id and branch_head_trial_id != parent_trial_id:
+                    new_branch = self.create_branch(branch_head_commit_id)
+                    self.switch_branch(new_branch)
+                else:
+                    self._set_head(current_branch_ref)
+
+                if branch_head_commit_id is not None:
+                    commit.parents = [branch_head_commit_id]
 
             commit.tree = tree
             author = (self._commit_name + " <" + self._commit_email + ">").encode()
@@ -106,17 +119,21 @@ def create_commit_object(self, message, tree, trial_id=None):
             commit.message = message.encode()
 
             self.repo.object_store.add_object(commit)
-            self.repo.refs[branch_ref] = commit.id
-            if trial_id:
-                self.repo.refs[self.trial_ref(trial_id).encode("utf-8")] = commit.id
+
+            self.repo.refs[
+                self._commit_ref.encode("utf-8")
+            ] = commit.id
+
+            self.repo.refs[
+                self.trial_ref(trial_id).encode("utf-8")
+            ] = commit.id
 
             return commit.id
 
     def commit_content(self, message, trial_id=None):
         """Commit the current files and update branch/trial refs"""
-        commit_id = super(DulwichEngine, self).commit_content(message)
-        if trial_id:
-            self.repo.refs[self.trial_ref(trial_id).encode("utf-8")] = commit_id
+        empty_tree = Tree()
+        commit_id = self.create_commit_object(message, empty_tree.id, trial_id)
         return commit_id
 
     def new_tree(self, parent):
@@ -137,8 +154,6 @@ def write_tree(self, tree):
             self.repo.object_store.add_object(tree)
             return tree.id
 
-    # Branch prototype API
-
     @staticmethod
     def _to_text(value):
         if value is None:
@@ -155,21 +170,53 @@ def _to_hex(value):
             return value.decode("ascii")
         return str(value)
 
-    @staticmethod
-    def _valid_branch_name(name):
-        return (
-            name and
-            ".." not in name and
-            not name.startswith("/") and
-            not name.endswith("/") and
-            not name.endswith(".lock") and
-            all(ch not in name for ch in " ~^:?*[\\")
-        )
+    def get_commit_id_by_trial_id(self, trial_id):
+        """Return commit id for a trial ref"""
+        return self.repo.get_refs().get(self.trial_ref(trial_id).encode("utf-8"))
+
+    def get_trial_id_by_commit_id(self, commit_id):
+        """Find trial id by commit id"""
+        if not commit_id:
+            return None
+        wanted = self._to_hex(commit_id)
+
+        prefix = self._trial_ref_prefix
+
+        with self.use_safe_open():
+            for ref, value in self.repo.get_refs().items():
+                ref = self._to_text(ref)
+                if ref.startswith(prefix) and value == commit_id:
+                    return ref[len(prefix):]
+        return None
+
+    def get_branch_head_trial_id(self, name=None):
+        """Return trial_id at the named branch head"""
+        """If no name is given, return trial_id current branch head"""
+        return self.get_trial_id_by_commit_id(self.get_branch_head_commit_id(name))
+
+    def get_branch_head_commit_id(self, name=None):
+        """Return commit_id at the named branch head"""
+        """If no name is given, return commit_id current branch head"""
+        with self.use_safe_open():
+            if name != None:
+                branch_ref = self.branch_ref(name)
+            else:
+                branch_name, branch_ref = self.current_branch()
+
+            commit_id = self.repo.get_refs().get(branch_ref.encode("utf-8"))
+            return commit_id
+
+    def branches(self):
+        """Return branch names in content.git"""
+        result = []
+        for ref in self.repo.get_refs():
+            ref = self._to_text(ref)
+            if ref.startswith("refs/heads/"):
+                result.append(ref.rsplit("/", 1)[-1])
+        return sorted(result)
 
     def branch_ref(self, name):
         """Return a full Git branch ref"""
-        if not self._valid_branch_name(name):
-            raise RuntimeError("invalid branch name: {}".format(name))
         return "refs/heads/{}".format(name)
 
     def trial_ref(self, trial_id):
@@ -186,81 +233,37 @@ def _set_head(self, branch_ref):
                 fil.write(b"ref: " + ref + b"\n")
         self._commit_ref = branch_ref
 
-    def _current_branch_ref(self):
-        """Return current branch ref, upgrading old stores lazily"""
-        try:
-            head = self.repo.refs.read_ref(b"HEAD")
-        except (AttributeError, KeyError):
-            head = None
-        head = head.decode("utf-8")
-        if head and head.startswith("refs/heads/"):
-            return head
-
-        refs = self.repo.get_refs()
-        for candidate in ("refs/heads/master", "refs/heads/main"):
-            if candidate in refs:
-                self._set_head(candidate)
-                return candidate
-
-        branch_ref = self.branch_ref(self._default_branch)
-        self._set_head(branch_ref)
-        return branch_ref
-
     def current_branch(self):
-        """Return the current branch name"""
-        ref = self._current_branch_ref()
-        return ref.rsplit("/", 1)[-1]
-
-    def branches(self):
-        """Return branch names in content.git"""
-        result = []
-        for ref in self.repo.get_refs():
-            if ref.startswith("refs/heads/"):
-                result.append(ref.rsplit("/", 1)[-1])
-        return sorted(result)
-
-
-    def get_commit_id_by_trial_id(self, trial_id):
-        """Return commit id for a trial ref"""
-        return self.repo.get_refs().get(self.trial_ref(trial_id).encode("utf-8"))
+        """Return the current branch name and ref"""
+        with self.use_safe_open():
+            ref_chain, commit_sha = self.repo.refs.follow(b'HEAD')
+            full_name = ref_chain[1].decode('utf-8')
+            return full_name.rsplit("/")[-1], full_name
 
-    def get_trial_id_by_commit_id(self, commit_id):
-        """Find trial id by commit id"""
+    def create_branch(self, commit_id):
+        """Create branch pointing to commit id"""
         if not commit_id:
-            return None
-        wanted = self._to_hex(commit_id)
-        prefix = self._trial_ref_prefix
-        for ref, value in self.repo.get_refs().items():
-            ref = self._to_text(ref)
-            if ref.startswith(prefix) and value == commit_id:
-                return ref[len(prefix):]
-        return None
+            raise RuntimeError("cannot create branch without a commit")
 
-    def get_branch_head_trial_id(self, name=None):
-        """Return trial_id at the named branch head"""
-        """If no name is given, return trial_id current branch head"""
-        return self.get_trial_id_by_commit_id(self.get_branch_head_commit_id(name))
+        trial_id = self.get_trial_id_by_commit_id(commit_id)
 
-    def get_branch_head_commit_id(self, name=None):
-        """Return commit_id at the named branch head"""
-        """If no name is given, return commit_id current branch head"""
-        branch_ref = self.branch_ref(name) if name else self._current_branch_ref()
-        commit_id = self.repo.get_refs().get(branch_ref.encode("utf-8"))
-        return commit_id
+        name = "now-diverge-{}".format(str(trial_id)[:8])
+        index = 1
+        existing = set(self.branches())
 
-    def create_branch(self, name, commit_id):
-        """Create branch pointing to commit id"""
-        if not commit_id:
-            raise RuntimeError("cannot create branch without a commit")
-        branch_ref = self.branch_ref(name)
-        if branch_ref in self.repo.get_refs():
-            raise RuntimeError("branch already exists: {}".format(name))
-        self.repo.refs[branch_ref] = commit_id.encode("ascii")
+        while name in existing:
+            index += 1
+            name = "{}-{}".format(name, index)
+
+        encoded_ref = (self.branch_ref(name)).encode("utf-8")
+        self.repo.refs[encoded_ref] = commit_id
+        return name
 
     def switch_branch(self, name):
         """Switch HEAD to branch"""
         branch_ref = self.branch_ref(name)
-        if branch_ref not in self.repo.get_refs():
+        encoded_ref = (branch_ref).encode("utf-8")
+        if encoded_ref not in self.repo.get_refs():
             raise RuntimeError("branch not found: {}".format(name))
         self._set_head(branch_ref)
 
@@ -277,64 +280,10 @@ def rename_branch(self, old, new):
             raise RuntimeError("branch already exists: {}".format(new))
         self.repo.refs[new_key] = refs[old_key]
         del self.repo.refs[old_key]
-        if self._current_branch_ref() == old_ref:
-            self._set_head(new_ref)
-
-    def ensure_branch_for_trial(self, trial_id):
-        """Create and switch to an automatic branch for a restored trial"""
-        current_trial = self.current_branch_trial()
-        if current_trial == str(trial_id):
-            return self.current_branch()
-
-        commit_id = self.trial_commit(trial_id)
-        if not commit_id:
-            return self.current_branch()
-
-        base = "now-diverge-{}".format(str(trial_id)[:8])
-        name = base
-        index = 1
-        existing = set(self.branches())
-        while name in existing:
-            index += 1
-            name = "{}-{}".format(base, index)
-        self.create_branch(name, commit_id)
-        self.switch_branch(name)
-        return name
-
-    def checkout_branch(self, name):
-        """Switch branch and restore versioned files from its tree"""
-        self.switch_branch(name)
-        commit_id = self.branch_commit(name)
-        if not commit_id:
-            return
-        commit = self.repo[commit_id.encode("ascii")]
-        self._checkout_tree(commit.tree, "")
-
-    def _tree_items(self, tree):
-        if hasattr(tree, "iteritems"):
-            return tree.iteritems()
-        return tree.items()
-
-    def _checkout_tree(self, tree_id, prefix):
-        tree = self.repo[tree_id]
-        for item in self._tree_items(tree):
-            if len(item) == 3:
-                name, mode, sha = item
-            else:
-                name, entry = item
-                mode, sha = entry.mode, entry.sha
-            relative = posixpath.join(prefix, name) if prefix else name
-            obj = self.repo[sha]
-            if isinstance(obj, Tree):
-                self._checkout_tree(sha, relative)
-            else:
-                path = os.path.join(self.base_path, *relative.split("/"))
-                parent = os.path.dirname(path)
-                if parent:
-                    os.makedirs(parent, exist_ok=True)
-                with self.std_open(path, "wb") as fil:
-                    fil.write(obj.as_raw_string())
 
+        _, current_name_ref = self.current_branch()
+        if current_name_ref == old_ref:
+            self._set_head(new_ref)
 
 DistributedDulwichEngine = create_distributed(DulwichEngine)
 PoolDulwichEngine = create_pool(DulwichEngine)
diff --git a/src/noworkflow/now/persistence/content/gitbase.py b/src/noworkflow/now/persistence/content/gitbase.py
index 8e34fc11..922941ee 100644
--- a/src/noworkflow/now/persistence/content/gitbase.py
+++ b/src/noworkflow/now/persistence/content/gitbase.py
@@ -20,6 +20,8 @@ def __init__(self, config):
         self._default_branch = 'master'
         self._trial_ref_prefix = 'refs/noworkflow/trials/'
         self._initial_message = "Initial Commit"
+        self._default_branch = 'master'
+        self._trial_ref_prefix = 'refs/noworkflow/trials/'
         self.name_counter = Counter()
         self.base_path = None
         self.user_path = os.path.expanduser("~")

From f85a9f94d4c16c87f5624b0f9a72500d035d7f66 Mon Sep 17 00:00:00 2001
From: Felipe Coutinho <felipe_coutinho@id.uff.br>
Date: Mon, 1 Jun 2026 15:54:22 -0300
Subject: [PATCH 4/4] Refactor

---
 src/noworkflow/now/cmd/cmd_branch.py          | 17 ++++-----
 .../now/persistence/content/dulwich_engine.py | 37 ++++++++++---------
 .../now/persistence/content/gitbase.py        |  2 -
 .../now/persistence/content/parallel.py       | 22 +++--------
 .../now/persistence/models/trial.py           | 11 ++----
 5 files changed, 37 insertions(+), 52 deletions(-)

diff --git a/src/noworkflow/now/cmd/cmd_branch.py b/src/noworkflow/now/cmd/cmd_branch.py
index c459ed95..0de5002b 100644
--- a/src/noworkflow/now/cmd/cmd_branch.py
+++ b/src/noworkflow/now/cmd/cmd_branch.py
@@ -48,21 +48,20 @@ def _connect(self, args):
     def execute(self, args):
         self._connect(args)
         command = args.branch_cmd or "list"
+        current, _ = content.current_branch()
 
         if command == "list":
-            current = content.current_branch()
             for name in content.branches():
                 marker = "*" if name == current else " "
-                trial_id = content.branch_trial(name) or "<no trial>"
-                print("{} {} {}".format(marker, name, trial_id))
+                print("{} {}".format(marker, name))
         elif command == "current":
-            trial_id = content.current_branch_trial() or "<no trial>"
-            print("{} {}".format(content.current_branch(), trial_id))
+            print("{}".format(current))
         elif command == "switch":
-            content.checkout_branch(args.name)
-            trial_id = content.branch_trial(args.name)
-            if trial_id:
-                Trial(trial_id).create_head()
+            # TODO: IMPLEMENT this
+            # content.checkout_branch(args.name)
+            # trial_id = content.get_branch_head_trial_id(args.name)
+            # if trial_id:
+            #     Trial(trial_id).create_head()
             print_msg("Switched to branch {}".format(args.name), True)
         elif command == "rename":
             content.rename_branch(args.old, args.new)
diff --git a/src/noworkflow/now/persistence/content/dulwich_engine.py b/src/noworkflow/now/persistence/content/dulwich_engine.py
index 955c8d6c..9dd54f29 100644
--- a/src/noworkflow/now/persistence/content/dulwich_engine.py
+++ b/src/noworkflow/now/persistence/content/dulwich_engine.py
@@ -2,7 +2,6 @@
 import hashlib
 import time
 import io
-import posixpath
 
 from dulwich import file
 from dulwich.repo import Repo
@@ -36,7 +35,7 @@ def connect(self, config):
             self.create_initial_commit()
         else:
             self.repo = Repo(self.content_path)
-            self._commit_ref = self._current_branch_ref()
+            _, self._commit_ref = self.current_branch()
 
     @staticmethod
     def do_put(content_path, object_hashes, lock, content, filename):
@@ -154,21 +153,9 @@ def write_tree(self, tree):
             self.repo.object_store.add_object(tree)
             return tree.id
 
-    @staticmethod
-    def _to_text(value):
-        if value is None:
-            return None
-        if isinstance(value, bytes):
-            return value.decode("utf-8")
-        return value
-
-    @staticmethod
-    def _to_hex(value):
-        if value is None:
-            return None
-        if isinstance(value, bytes):
-            return value.decode("ascii")
-        return str(value)
+    #####################################################################
+    ## Branch Implementation
+    #####################################################################
 
     def get_commit_id_by_trial_id(self, trial_id):
         """Return commit id for a trial ref"""
@@ -285,6 +272,22 @@ def rename_branch(self, old, new):
         if current_name_ref == old_ref:
             self._set_head(new_ref)
 
+    @staticmethod
+    def _to_text(value):
+        if value is None:
+            return None
+        if isinstance(value, bytes):
+            return value.decode("utf-8")
+        return value
+
+    @staticmethod
+    def _to_hex(value):
+        if value is None:
+            return None
+        if isinstance(value, bytes):
+            return value.decode("ascii")
+        return str(value)
+
 DistributedDulwichEngine = create_distributed(DulwichEngine)
 PoolDulwichEngine = create_pool(DulwichEngine)
 ThreadingDulwichEngine = create_threading(DulwichEngine)
diff --git a/src/noworkflow/now/persistence/content/gitbase.py b/src/noworkflow/now/persistence/content/gitbase.py
index 922941ee..8e34fc11 100644
--- a/src/noworkflow/now/persistence/content/gitbase.py
+++ b/src/noworkflow/now/persistence/content/gitbase.py
@@ -20,8 +20,6 @@ def __init__(self, config):
         self._default_branch = 'master'
         self._trial_ref_prefix = 'refs/noworkflow/trials/'
         self._initial_message = "Initial Commit"
-        self._default_branch = 'master'
-        self._trial_ref_prefix = 'refs/noworkflow/trials/'
         self.name_counter = Counter()
         self.base_path = None
         self.user_path = os.path.expanduser("~")
diff --git a/src/noworkflow/now/persistence/content/parallel.py b/src/noworkflow/now/persistence/content/parallel.py
index 5d76b31e..61b1579c 100644
--- a/src/noworkflow/now/persistence/content/parallel.py
+++ b/src/noworkflow/now/persistence/content/parallel.py
@@ -24,10 +24,8 @@ def run(self):
                     self.task_queue.task_done()
                     break
 
-                try:
-                    self.engine.do_put(*queue_content)
-                finally:
-                    self.task_queue.task_done()
+                self.engine.do_put(*queue_content)
+                self.task_queue.task_done()
 
 
     class Distributed(cls):
@@ -52,7 +50,6 @@ def start_processes(self):
             with safeopen.use_safe_open():
                 for _ in range(self.num_consumers):
                     consumer = Worker(self.tasks, self)
-                    consumer.daemon = True
                     self.consumers.append(consumer)
                     consumer.start()
 
@@ -72,18 +69,9 @@ def close(self):
                 for _ in range(self.num_consumers):
                     self.tasks.put(None)
 
-                try:
-                    # Wait for all of the tasks to finish
-                    self.tasks.join()
-                    for consumer in self.consumers:
-                        consumer.join()
-                finally:
-                    for consumer in self.consumers:
-                        if consumer.is_alive():
-                            consumer.terminate()
-                            consumer.join()
-                    self.consumers = []
-                    self.processes_started = False
+                # Wait for all of the tasks to finish
+                self.tasks.join()
+                self.processes_started = False
         
     Distributed.__name__ = name or ("Distributed" + cls.__name__)
     return Distributed
diff --git a/src/noworkflow/now/persistence/models/trial.py b/src/noworkflow/now/persistence/models/trial.py
index a62a563d..1d021121 100644
--- a/src/noworkflow/now/persistence/models/trial.py
+++ b/src/noworkflow/now/persistence/models/trial.py
@@ -1052,19 +1052,16 @@ def load_parent(cls, script, remove=True, check=False, session=None):
         """
         session = session or relational.session
         head = Head.load_head(script, session=session)
-
         if head:
-            content.ensure_branch_for_trial(head.trial.id)
             trial = head.trial
             if remove:
                 Head.remove(head.id, session=relational.make_session())
-            return proxy(trial)
-
-        trial_id = content.get_branch_head_trial_id()
-        trial = cls.load_trial(trial_id, session=session)
+        elif not head:
+            trial = cls.last_trial(
+                script=script, check=check,
+                session=session)
         return proxy(trial)
 
-
     @classmethod  # query
     def fast_last_trial_id(cls, session=None):
         """Load last trial id that did not bypass modules