feat(memory): add git-backed version control for dream memory files (#2753)

- Add GitStore class wrapping dulwich for memory file versioning
- Auto-commit memory changes during Dream consolidation
- Add /dream-log and /dream-restore commands for history browsing
- Pass tracked_files as constructor param, generate .gitignore dynamically

nanobot/agent/git_store.py

@@ -0,0 +1,299 @@
+"""Git-backed version control for memory files, using dulwich."""
+
+from __future__ import annotations
+
+import io
+import time
+from dataclasses import dataclass
+from pathlib import Path
+
+from loguru import logger
+
+
+@dataclass
+class CommitInfo:
+    sha: str  # Short SHA (8 chars)
+    message: str
+    timestamp: str  # Formatted datetime
+
+    def format(self, diff: str = "") -> str:
+        """Format this commit for display, optionally with a diff."""
+        header = f"## {self.message.splitlines()[0]}\n`{self.sha}` — {self.timestamp}\n"
+        if diff:
+            return f"{header}\n```diff\n{diff}\n```"
+        return f"{header}\n(no file changes)"
+
+
+class GitStore:
+    """Git-backed version control for memory files."""
+
+    def __init__(self, workspace: Path, tracked_files: list[str]):
+        self._workspace = workspace
+        self._tracked_files = tracked_files
+
+    def is_initialized(self) -> bool:
+        """Check if the git repo has been initialized."""
+        return (self._workspace / ".git").is_dir()
+
+    # -- init ------------------------------------------------------------------
+
+    def init(self) -> bool:
+        """Initialize a git repo if not already initialized.
+
+        Creates .gitignore and makes an initial commit.
+        Returns True if a new repo was created, False if already exists.
+        """
+        if self.is_initialized():
+            return False
+
+        try:
+            from dulwich import porcelain
+
+            porcelain.init(str(self._workspace))
+
+            # Write .gitignore
+            gitignore = self._workspace / ".gitignore"
+            gitignore.write_text(self._build_gitignore(), encoding="utf-8")
+
+            # Ensure tracked files exist (touch them if missing) so the initial
+            # commit has something to track.
+            for rel in self._tracked_files:
+                p = self._workspace / rel
+                p.parent.mkdir(parents=True, exist_ok=True)
+                if not p.exists():
+                    p.write_text("", encoding="utf-8")
+
+            # Initial commit
+            porcelain.add(str(self._workspace), paths=[".gitignore"] + self._tracked_files)
+            porcelain.commit(
+                str(self._workspace),
+                message=b"init: nanobot memory store",
+                author=b"nanobot <nanobot@dream>",
+                committer=b"nanobot <nanobot@dream>",
+            )
+            logger.info("Git store initialized at {}", self._workspace)
+            return True
+        except Exception:
+            logger.warning("Git store init failed for {}", self._workspace)
+            return False
+
+    # -- daily operations ------------------------------------------------------
+
+    def auto_commit(self, message: str) -> str | None:
+        """Stage tracked memory files and commit if there are changes.
+
+        Returns the short commit SHA, or None if nothing to commit.
+        """
+        if not self.is_initialized():
+            return None
+
+        try:
+            from dulwich import porcelain
+
+            # .gitignore excludes everything except tracked files,
+            # so any staged/unstaged change must be in our files.
+            st = porcelain.status(str(self._workspace))
+            if not st.unstaged and not any(st.staged.values()):
+                return None
+
+            msg_bytes = message.encode("utf-8") if isinstance(message, str) else message
+            porcelain.add(str(self._workspace), paths=self._tracked_files)
+            sha_bytes = porcelain.commit(
+                str(self._workspace),
+                message=msg_bytes,
+                author=b"nanobot <nanobot@dream>",
+                committer=b"nanobot <nanobot@dream>",
+            )
+            if sha_bytes is None:
+                return None
+            sha = sha_bytes.hex()[:8]
+            logger.debug("Git auto-commit: {} ({})", sha, message)
+            return sha
+        except Exception:
+            logger.warning("Git auto-commit failed: {}", message)
+            return None
+
+    # -- internal helpers ------------------------------------------------------
+
+    def _resolve_sha(self, short_sha: str) -> bytes | None:
+        """Resolve a short SHA prefix to the full SHA bytes."""
+        try:
+            from dulwich.repo import Repo
+
+            with Repo(str(self._workspace)) as repo:
+                try:
+                    sha = repo.refs[b"HEAD"]
+                except KeyError:
+                    return None
+
+                while sha:
+                    if sha.hex().startswith(short_sha):
+                        return sha
+                    commit = repo[sha]
+                    if commit.type_name != b"commit":
+                        break
+                    sha = commit.parents[0] if commit.parents else None
+            return None
+        except Exception:
+            return None
+
+    def _build_gitignore(self) -> str:
+        """Generate .gitignore content from tracked files."""
+        dirs: set[str] = set()
+        for f in self._tracked_files:
+            parent = str(Path(f).parent)
+            if parent != ".":
+                dirs.add(parent)
+        lines = ["/*"]
+        for d in sorted(dirs):
+            lines.append(f"!{d}/")
+        for f in self._tracked_files:
+            lines.append(f"!{f}")
+        lines.append("!.gitignore")
+        return "\n".join(lines) + "\n"
+
+    # -- query -----------------------------------------------------------------
+
+    def log(self, max_entries: int = 20) -> list[CommitInfo]:
+        """Return simplified commit log."""
+        if not self.is_initialized():
+            return []
+
+        try:
+            from dulwich.repo import Repo
+
+            entries: list[CommitInfo] = []
+            with Repo(str(self._workspace)) as repo:
+                try:
+                    head = repo.refs[b"HEAD"]
+                except KeyError:
+                    return []
+
+                sha = head
+                while sha and len(entries) < max_entries:
+                    commit = repo[sha]
+                    if commit.type_name != b"commit":
+                        break
+                    ts = time.strftime(
+                        "%Y-%m-%d %H:%M",
+                        time.localtime(commit.commit_time),
+                    )
+                    msg = commit.message.decode("utf-8", errors="replace").strip()
+                    entries.append(CommitInfo(
+                        sha=sha.hex()[:8],
+                        message=msg,
+                        timestamp=ts,
+                    ))
+                    sha = commit.parents[0] if commit.parents else None
+
+            return entries
+        except Exception:
+            logger.warning("Git log failed")
+            return []
+
+    def diff_commits(self, sha1: str, sha2: str) -> str:
+        """Show diff between two commits."""
+        if not self.is_initialized():
+            return ""
+
+        try:
+            from dulwich import porcelain
+
+            full1 = self._resolve_sha(sha1)
+            full2 = self._resolve_sha(sha2)
+            if not full1 or not full2:
+                return ""
+
+            out = io.BytesIO()
+            porcelain.diff(
+                str(self._workspace),
+                commit=full1,
+                commit2=full2,
+                outstream=out,
+            )
+            return out.getvalue().decode("utf-8", errors="replace")
+        except Exception:
+            logger.warning("Git diff_commits failed")
+            return ""
+
+    def find_commit(self, short_sha: str, max_entries: int = 20) -> CommitInfo | None:
+        """Find a commit by short SHA prefix match."""
+        for c in self.log(max_entries=max_entries):
+            if c.sha.startswith(short_sha):
+                return c
+        return None
+
+    def show_commit_diff(self, short_sha: str, max_entries: int = 20) -> tuple[CommitInfo, str] | None:
+        """Find a commit and return it with its diff vs the parent."""
+        commits = self.log(max_entries=max_entries)
+        for i, c in enumerate(commits):
+            if c.sha.startswith(short_sha):
+                if i + 1 < len(commits):
+                    diff = self.diff_commits(commits[i + 1].sha, c.sha)
+                else:
+                    diff = ""
+                return c, diff
+        return None
+
+    # -- restore ---------------------------------------------------------------
+
+    def revert(self, commit: str) -> str | None:
+        """Restore all tracked memory files to their state at the given commit.
+
+        This reads the file contents from the target commit, writes them back,
+        and creates a new commit. Does not require merge3.
+        Returns the new commit SHA, or None on failure.
+        """
+        if not self.is_initialized():
+            return None
+
+        try:
+            from dulwich.repo import Repo
+
+            full_sha = self._resolve_sha(commit)
+            if not full_sha:
+                logger.warning("Git revert: SHA not found: {}", commit)
+                return None
+
+            restored: list[str] = []
+            with Repo(str(self._workspace)) as repo:
+                commit_obj = repo[full_sha]
+                if commit_obj.type_name != b"commit":
+                    return None
+                tree = repo[commit_obj.tree]
+
+                for filepath in self._tracked_files:
+                    content = self._read_blob_from_tree(repo, tree, filepath)
+                    if content is not None:
+                        dest = self._workspace / filepath
+                        dest.write_text(content, encoding="utf-8")
+                        restored.append(filepath)
+
+            if not restored:
+                return None
+
+            # Commit the restored state
+            msg = f"revert: restore to {commit}"
+            return self.auto_commit(msg)
+        except Exception:
+            logger.warning("Git revert failed for {}", commit)
+            return None
+
+    @staticmethod
+    def _read_blob_from_tree(repo, tree, filepath: str) -> str | None:
+        """Read a blob's content from a tree object by walking path parts."""
+        parts = Path(filepath).parts
+        current = tree
+        for part in parts:
+            try:
+                entry = current[part.encode()]
+            except KeyError:
+                return None
+            obj = repo[entry[1]]
+            if obj.type_name == b"blob":
+                return obj.data.decode("utf-8", errors="replace")
+            if obj.type_name == b"tree":
+                current = obj
+            else:
+                return None
+        return None

nanobot/agent/memory.py

@@ -15,6 +15,7 @@ from nanobot.utils.helpers import ensure_dir, estimate_message_tokens, estimate_
 
 from nanobot.agent.runner import AgentRunSpec, AgentRunner
 from nanobot.agent.tools.registry import ToolRegistry
+from nanobot.agent.git_store import GitStore
 
 if TYPE_CHECKING:
     from nanobot.providers.base import LLMProvider
@@ -41,6 +42,13 @@ class MemoryStore:
         self._dream_log_file = self.memory_dir / ".dream-log.md"
         self._cursor_file = self.memory_dir / ".cursor"
         self._dream_cursor_file = self.memory_dir / ".dream_cursor"
+        self._git = GitStore(workspace, tracked_files=[
+            "SOUL.md", "USER.md", "memory/MEMORY.md",
+        ])
+
+    @property
+    def git(self) -> GitStore:
+        return self._git
 
     # -- generic helpers -----------------------------------------------------
 
@@ -576,4 +584,10 @@ class Dream:
         else:
             self.store.append_dream_log(f"## {ts}\nNo changes.\n")
 
+        # Git auto-commit (only when there are actual changes)
+        if changelog and self.store.git.is_initialized():
+            sha = self.store.git.auto_commit(f"dream: {ts}, {len(changelog)} change(s)")
+            if sha:
+                logger.info("Dream commit: {}", sha)
+
         return True

nanobot/command/builtin.py

@@ -103,23 +103,86 @@ async def cmd_dream(ctx: CommandContext) -> OutboundMessage:
 
 
 async def cmd_dream_log(ctx: CommandContext) -> OutboundMessage:
-    """Show the Dream consolidation log."""
+    """Show what the last Dream changed.
-    loop = ctx.loop
+
-    store = loop.consolidator.store
+    Default: diff of the latest commit (HEAD~1 vs HEAD).
-    log = store.read_dream_log()
+    With /dream-log <sha>: diff of that specific commit.
-    if not log:
+    """
-        # Check if Dream has ever processed anything
+    store = ctx.loop.consolidator.store
+    git = store.git
+
+    if not git.is_initialized():
         if store.get_last_dream_cursor() == 0:
-            content = "Dream has not run yet."
+            msg = "Dream has not run yet."
         else:
-            content = "No dream log yet."
+            msg = "Git not initialized for memory files."
+        return OutboundMessage(
+            channel=ctx.msg.channel, chat_id=ctx.msg.chat_id,
+            content=msg, metadata={"render_as": "text"},
+        )
+
+    args = ctx.args.strip()
+
+    if args:
+        # Show diff of a specific commit
+        sha = args.split()[0]
+        result = git.show_commit_diff(sha)
+        if not result:
+            content = f"Commit `{sha}` not found."
+        else:
+            commit, diff = result
+            content = commit.format(diff)
     else:
-        content = f"## Dream Log\n\n{log}"
+        # Default: show the latest commit's diff
+        result = git.show_commit_diff(git.log(max_entries=1)[0].sha) if git.log(max_entries=1) else None
+        if result:
+            commit, diff = result
+            content = commit.format(diff)
+        else:
+            content = "No commits yet."
+
     return OutboundMessage(
-        channel=ctx.msg.channel,
+        channel=ctx.msg.channel, chat_id=ctx.msg.chat_id,
-        chat_id=ctx.msg.chat_id,
+        content=content, metadata={"render_as": "text"},
-        content=content,
+    )
-        metadata={"render_as": "text"},
+
+
+async def cmd_dream_restore(ctx: CommandContext) -> OutboundMessage:
+    """Restore memory files from a previous dream commit.
+
+    Usage:
+        /dream-restore          — list recent commits
+        /dream-restore <sha>    — revert a specific commit
+    """
+    store = ctx.loop.consolidator.store
+    git = store.git
+    if not git.is_initialized():
+        return OutboundMessage(
+            channel=ctx.msg.channel, chat_id=ctx.msg.chat_id,
+            content="Git not initialized for memory files.",
+        )
+
+    args = ctx.args.strip()
+    if not args:
+        # Show recent commits for the user to pick
+        commits = git.log(max_entries=10)
+        if not commits:
+            content = "No commits found."
+        else:
+            lines = ["## Recent Dream Commits\n", "Use `/dream-restore <sha>` to revert a commit.\n"]
+            for c in commits:
+                lines.append(f"- `{c.sha}` {c.message.splitlines()[0]} ({c.timestamp})")
+            content = "\n".join(lines)
+    else:
+        sha = args.split()[0]
+        new_sha = git.revert(sha)
+        if new_sha:
+            content = f"Reverted commit `{sha}` → new commit `{new_sha}`."
+        else:
+            content = f"Failed to revert commit `{sha}`. Check if the SHA is correct."
+    return OutboundMessage(
+        channel=ctx.msg.channel, chat_id=ctx.msg.chat_id,
+        content=content, metadata={"render_as": "text"},
     )
 
 
@@ -142,7 +205,8 @@ def build_help_text() -> str:
         "/restart — Restart the bot",
         "/status — Show bot status",
         "/dream — Manually trigger Dream consolidation",
-        "/dream-log — Show Dream consolidation log",
+        "/dream-log — Show what the last Dream changed",
+        "/dream-restore — Revert memory to a previous state",
         "/help — Show available commands",
     ]
     return "\n".join(lines)
@@ -157,4 +221,7 @@ def register_builtin_commands(router: CommandRouter) -> None:
     router.exact("/status", cmd_status)
     router.exact("/dream", cmd_dream)
     router.exact("/dream-log", cmd_dream_log)
+    router.prefix("/dream-log ", cmd_dream_log)
+    router.exact("/dream-restore", cmd_dream_restore)
+    router.prefix("/dream-restore ", cmd_dream_restore)
     router.exact("/help", cmd_help)

nanobot/utils/helpers.py

@@ -303,4 +303,15 @@ def sync_workspace_templates(workspace: Path, silent: bool = False) -> list[str]
         from rich.console import Console
         for name in added:
             Console().print(f"  [dim]Created {name}[/dim]")
+
+    # Initialize git for memory version control
+    try:
+        from nanobot.agent.git_store import GitStore
+        gs = GitStore(workspace, tracked_files=[
+            "SOUL.md", "USER.md", "memory/MEMORY.md",
+        ])
+        gs.init()
+    except Exception:
+        pass
+
     return added

pyproject.toml

@@ -48,6 +48,7 @@ dependencies = [
     "chardet>=3.0.2,<6.0.0",
     "openai>=2.8.0",
     "tiktoken>=0.12.0,<1.0.0",
+    "dulwich>=0.22.0,<1.0.0",
 ]
 
 [project.optional-dependencies]

tests/agent/test_git_store.py

@@ -0,0 +1,225 @@
+"""Tests for GitStore — git-backed version control for memory files."""
+
+import pytest
+from pathlib import Path
+
+from nanobot.agent.git_store import GitStore, CommitInfo
+
+
+TRACKED = ["SOUL.md", "USER.md", "memory/MEMORY.md"]
+
+
+@pytest.fixture
+def git(tmp_path):
+    """Uninitialized GitStore."""
+    return GitStore(tmp_path, tracked_files=TRACKED)
+
+
+@pytest.fixture
+def git_ready(git):
+    """Initialized GitStore with one initial commit."""
+    git.init()
+    return git
+
+
+class TestInit:
+    def test_not_initialized_by_default(self, git, tmp_path):
+        assert not git.is_initialized()
+        assert not (tmp_path / ".git").is_dir()
+
+    def test_init_creates_git_dir(self, git, tmp_path):
+        assert git.init()
+        assert (tmp_path / ".git").is_dir()
+
+    def test_init_idempotent(self, git_ready):
+        assert not git_ready.init()
+
+    def test_init_creates_gitignore(self, git_ready):
+        gi = git_ready._workspace / ".gitignore"
+        assert gi.exists()
+        content = gi.read_text(encoding="utf-8")
+        for f in TRACKED:
+            assert f"!{f}" in content
+
+    def test_init_touches_tracked_files(self, git_ready):
+        for f in TRACKED:
+            assert (git_ready._workspace / f).exists()
+
+    def test_init_makes_initial_commit(self, git_ready):
+        commits = git_ready.log()
+        assert len(commits) == 1
+        assert "init" in commits[0].message
+
+
+class TestBuildGitignore:
+    def test_subdirectory_dirs(self, git):
+        content = git._build_gitignore()
+        assert "!memory/\n" in content
+        for f in TRACKED:
+            assert f"!{f}\n" in content
+        assert content.startswith("/*\n")
+
+    def test_root_level_files_no_dir_entries(self, tmp_path):
+        gs = GitStore(tmp_path, tracked_files=["a.md", "b.md"])
+        content = gs._build_gitignore()
+        assert "!a.md\n" in content
+        assert "!b.md\n" in content
+        dir_lines = [l for l in content.split("\n") if l.startswith("!") and l.endswith("/")]
+        assert dir_lines == []
+
+
+class TestAutoCommit:
+    def test_returns_none_when_not_initialized(self, git):
+        assert git.auto_commit("test") is None
+
+    def test_commits_file_change(self, git_ready):
+        (git_ready._workspace / "SOUL.md").write_text("updated", encoding="utf-8")
+        sha = git_ready.auto_commit("update soul")
+        assert sha is not None
+        assert len(sha) == 8
+
+    def test_returns_none_when_no_changes(self, git_ready):
+        assert git_ready.auto_commit("no change") is None
+
+    def test_commit_appears_in_log(self, git_ready):
+        ws = git_ready._workspace
+        (ws / "SOUL.md").write_text("v2", encoding="utf-8")
+        sha = git_ready.auto_commit("update soul")
+        commits = git_ready.log()
+        assert len(commits) == 2
+        assert commits[0].sha == sha
+
+    def test_does_not_create_empty_commits(self, git_ready):
+        git_ready.auto_commit("nothing 1")
+        git_ready.auto_commit("nothing 2")
+        assert len(git_ready.log()) == 1  # only init commit
+
+
+class TestLog:
+    def test_empty_when_not_initialized(self, git):
+        assert git.log() == []
+
+    def test_newest_first(self, git_ready):
+        ws = git_ready._workspace
+        for i in range(3):
+            (ws / "SOUL.md").write_text(f"v{i}", encoding="utf-8")
+            git_ready.auto_commit(f"commit {i}")
+
+        commits = git_ready.log()
+        assert len(commits) == 4  # init + 3
+        assert "commit 2" in commits[0].message
+        assert "init" in commits[-1].message
+
+    def test_max_entries(self, git_ready):
+        ws = git_ready._workspace
+        for i in range(10):
+            (ws / "SOUL.md").write_text(f"v{i}", encoding="utf-8")
+            git_ready.auto_commit(f"c{i}")
+        assert len(git_ready.log(max_entries=3)) == 3
+
+    def test_commit_info_fields(self, git_ready):
+        c = git_ready.log()[0]
+        assert isinstance(c, CommitInfo)
+        assert len(c.sha) == 8
+        assert c.timestamp
+        assert c.message
+
+
+class TestDiffCommits:
+    def test_empty_when_not_initialized(self, git):
+        assert git.diff_commits("a", "b") == ""
+
+    def test_diff_between_two_commits(self, git_ready):
+        ws = git_ready._workspace
+        (ws / "SOUL.md").write_text("original", encoding="utf-8")
+        git_ready.auto_commit("v1")
+        (ws / "SOUL.md").write_text("modified", encoding="utf-8")
+        git_ready.auto_commit("v2")
+
+        commits = git_ready.log()
+        diff = git_ready.diff_commits(commits[1].sha, commits[0].sha)
+        assert "modified" in diff
+
+    def test_invalid_sha_returns_empty(self, git_ready):
+        assert git_ready.diff_commits("deadbeef", "cafebabe") == ""
+
+
+class TestFindCommit:
+    def test_finds_by_prefix(self, git_ready):
+        ws = git_ready._workspace
+        (ws / "SOUL.md").write_text("v2", encoding="utf-8")
+        sha = git_ready.auto_commit("v2")
+        found = git_ready.find_commit(sha[:4])
+        assert found is not None
+        assert found.sha == sha
+
+    def test_returns_none_for_unknown(self, git_ready):
+        assert git_ready.find_commit("deadbeef") is None
+
+
+class TestShowCommitDiff:
+    def test_returns_commit_with_diff(self, git_ready):
+        ws = git_ready._workspace
+        (ws / "SOUL.md").write_text("content", encoding="utf-8")
+        sha = git_ready.auto_commit("add content")
+        result = git_ready.show_commit_diff(sha)
+        assert result is not None
+        commit, diff = result
+        assert commit.sha == sha
+        assert "content" in diff
+
+    def test_first_commit_has_empty_diff(self, git_ready):
+        init_sha = git_ready.log()[-1].sha
+        result = git_ready.show_commit_diff(init_sha)
+        assert result is not None
+        _, diff = result
+        assert diff == ""
+
+    def test_returns_none_for_unknown(self, git_ready):
+        assert git_ready.show_commit_diff("deadbeef") is None
+
+
+class TestCommitInfoFormat:
+    def test_format_with_diff(self):
+        from nanobot.agent.git_store import CommitInfo
+        c = CommitInfo(sha="abcd1234", message="test commit\nsecond line", timestamp="2026-04-02 12:00")
+        result = c.format(diff="some diff")
+        assert "test commit" in result
+        assert "`abcd1234`" in result
+        assert "some diff" in result
+
+    def test_format_without_diff(self):
+        from nanobot.agent.git_store import CommitInfo
+        c = CommitInfo(sha="abcd1234", message="test", timestamp="2026-04-02 12:00")
+        result = c.format()
+        assert "(no file changes)" in result
+
+
+class TestRevert:
+    def test_returns_none_when_not_initialized(self, git):
+        assert git.revert("abc") is None
+
+    def test_reverts_file_content(self, git_ready):
+        ws = git_ready._workspace
+        (ws / "SOUL.md").write_text("v2 content", encoding="utf-8")
+        git_ready.auto_commit("v2")
+
+        commits = git_ready.log()
+        new_sha = git_ready.revert(commits[1].sha)  # revert to init
+        assert new_sha is not None
+        assert (ws / "SOUL.md").read_text(encoding="utf-8") == ""
+
+    def test_invalid_sha_returns_none(self, git_ready):
+        assert git_ready.revert("deadbeef") is None
+
+
+class TestMemoryStoreGitProperty:
+    def test_git_property_exposes_gitstore(self, tmp_path):
+        from nanobot.agent.memory import MemoryStore
+        store = MemoryStore(tmp_path)
+        assert isinstance(store.git, GitStore)
+
+    def test_git_property_is_same_object(self, tmp_path):
+        from nanobot.agent.memory import MemoryStore
+        store = MemoryStore(tmp_path)
+        assert store.git is store._git