diff --git a/src/auto_commit_service/database/connection.py b/src/auto_commit_service/database/connection.py
index 8b26532..01f8d9d 100644
--- a/src/auto_commit_service/database/connection.py
+++ b/src/auto_commit_service/database/connection.py
@@ -2,9 +2,10 @@
 
 import asyncio
 import logging
+from contextlib import asynccontextmanager
 from datetime import datetime, timedelta
 from pathlib import Path
-from typing import AsyncIterator
+from typing import Any, AsyncIterator
 
 from sqlalchemy import text
 from sqlalchemy.ext.asyncio import (
@@ -44,7 +45,7 @@ class DatabaseManager:
         self.database_url = f"sqlite+aiosqlite:///{self.db_path}"
         self.engine: AsyncEngine | None = None
         self.session_factory: async_sessionmaker[AsyncSession] | None = None
-        self._prune_task: asyncio.Task | None = None
+        self._prune_task: asyncio.Task[Any] | None = None
 
     async def connect(self) -> None:
         """Initialize database connection and create tables."""
@@ -66,6 +67,11 @@ class DatabaseManager:
         async with self.engine.begin() as conn:
             await conn.run_sync(Base.metadata.create_all)
 
+        # Apply schema migrations to add any missing columns
+        from .migrate import migrate_schema
+
+        await migrate_schema(self.engine)
+
         logger.info("Database initialized: %s", self.database_url)
 
         # Start background pruning task
@@ -86,6 +92,7 @@ class DatabaseManager:
 
         logger.info("Database connection closed")
 
+    @asynccontextmanager
     async def session(self) -> AsyncIterator[AsyncSession]:
         """Get database session context manager.
 
@@ -139,27 +146,28 @@ class DatabaseManager:
                 text("DELETE FROM commits WHERE timestamp < :cutoff"),
                 {"cutoff": cutoff_date},
             )
-            deleted["commits"] = result.rowcount or 0
+            deleted["commits"] = result.rowcount or 0  # type: ignore[attr-defined]
 
             # Delete old cycles
             result = await session.execute(
                 text("DELETE FROM cycles WHERE started_at < :cutoff"),
                 {"cutoff": cutoff_date},
             )
-            deleted["cycles"] = result.rowcount or 0
+            deleted["cycles"] = result.rowcount or 0  # type: ignore[attr-defined]
 
             # Delete old errors
             result = await session.execute(
                 text("DELETE FROM errors WHERE timestamp < :cutoff"),
                 {"cutoff": cutoff_date},
             )
-            deleted["errors"] = result.rowcount or 0
+            deleted["errors"] = result.rowcount or 0  # type: ignore[attr-defined]
 
             await session.commit()
 
         # Vacuum to reclaim space (SQLite)
-        async with self.engine.connect() as conn:
-            await conn.execute(text("VACUUM"))
+        if self.engine:
+            async with self.engine.connect() as conn:
+                await conn.execute(text("VACUUM"))
 
         new_size_mb = await self.get_database_size_mb()
         logger.info(
diff --git a/src/auto_commit_service/database/migrate.py b/src/auto_commit_service/database/migrate.py
new file mode 100644
index 0000000..112d0af
--- /dev/null
+++ b/src/auto_commit_service/database/migrate.py
@@ -0,0 +1,90 @@
+"""Database migration utilities.
+
+Handles schema migrations for the auto-commit service database.
+"""
+
+import logging
+from sqlalchemy import text
+from sqlalchemy.ext.asyncio import AsyncEngine
+
+logger = logging.getLogger(__name__)
+
+
+async def migrate_schema(engine: AsyncEngine) -> None:
+    """Apply schema migrations to bring database up to date.
+
+    Args:
+        engine: SQLAlchemy async engine
+    """
+    async with engine.begin() as conn:
+        # Migration 001: Add monorepo tracking fields to commits table
+        await _add_monorepo_fields(conn)
+
+        # Migration 002: Add hostname tracking to commits, cycles, errors
+        await _add_hostname_field(conn)
+
+    logger.info("Schema migrations completed successfully")
+
+
+async def _add_monorepo_fields(conn) -> None:
+    """Add monorepo tracking fields to commits table.
+
+    Adds:
+    - is_monorepo_parent (BOOLEAN)
+    - submodule_count (INTEGER)
+    - submodule_metadata (JSON)
+    """
+    # Check if columns already exist
+    result = await conn.execute(text("PRAGMA table_info(commits)"))
+    existing_columns = {row[1] for row in result}
+
+    migrations_needed = []
+
+    if "is_monorepo_parent" not in existing_columns:
+        migrations_needed.append(
+            "ALTER TABLE commits ADD COLUMN is_monorepo_parent BOOLEAN NOT NULL DEFAULT 0"
+        )
+
+    if "submodule_count" not in existing_columns:
+        migrations_needed.append(
+            "ALTER TABLE commits ADD COLUMN submodule_count INTEGER NOT NULL DEFAULT 0"
+        )
+
+    if "submodule_metadata" not in existing_columns:
+        migrations_needed.append(
+            "ALTER TABLE commits ADD COLUMN submodule_metadata JSON"
+        )
+
+    if migrations_needed:
+        logger.info("Adding monorepo tracking fields to commits table")
+        for migration in migrations_needed:
+            await conn.execute(text(migration))
+            logger.info(f"Applied: {migration}")
+    else:
+        logger.debug("Monorepo fields already exist in commits table")
+
+
+async def _add_hostname_field(conn) -> None:
+    """Add hostname field to commits, cycles, and errors tables.
+
+    Tracks which host produced each commit/cycle/error for multi-host setups.
+    """
+    tables = ["commits", "cycles", "errors"]
+
+    for table in tables:
+        result = await conn.execute(text(f"PRAGMA table_info({table})"))
+        existing_columns = {row[1] for row in result}
+
+        if "hostname" not in existing_columns:
+            await conn.execute(
+                text(f"ALTER TABLE {table} ADD COLUMN hostname VARCHAR(255)")
+            )
+            logger.info(f"Added hostname column to {table}")
+
+            # Create index
+            await conn.execute(
+                text(f"CREATE INDEX IF NOT EXISTS idx_{table}_hostname ON {table}(hostname)")
+            )
+            logger.info(f"Created hostname index on {table}")
+        else:
+            logger.debug(f"hostname column already exists in {table}")
diff --git a/src/auto_commit_service/database/models.py b/src/auto_commit_service/database/models.py
index 5d6cbd1..c98b15d 100644
--- a/src/auto_commit_service/database/models.py
+++ b/src/auto_commit_service/database/models.py
@@ -1,7 +1,7 @@
 """SQLAlchemy models for auto-commit database."""
 
 from datetime import datetime
-from typing import Optional
+from typing import Any, Optional
 
 from sqlalchemy import Index, String, Text, Integer, Float, Boolean, DateTime, JSON
 from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column
@@ -24,17 +24,54 @@ class Commit(Base):
     message: Mapped[str] = mapped_column(Text)
     timestamp: Mapped[datetime] = mapped_column(DateTime, index=True)
     daemon_id: Mapped[Optional[str]] = mapped_column(String(16), nullable=True)
+    hostname: Mapped[Optional[str]] = mapped_column(String(255), nullable=True, index=True)
     branch: Mapped[Optional[str]] = mapped_column(String(255), nullable=True)
     files_changed: Mapped[Optional[int]] = mapped_column(Integer, nullable=True)
     insertions: Mapped[Optional[int]] = mapped_column(Integer, nullable=True)
     deletions: Mapped[Optional[int]] = mapped_column(Integer, nullable=True)
 
+    # Monorepo/submodule tracking fields
+    is_monorepo_parent: Mapped[bool] = mapped_column(Boolean, default=False, nullable=False)
+    submodule_count: Mapped[int] = mapped_column(Integer, default=0, nullable=False)
+    submodule_metadata: Mapped[Optional[dict[str, Any]]] = mapped_column(JSON, nullable=True)
+
     __table_args__ = (
         Index("idx_commit_timestamp", "timestamp"),
         Index("idx_commit_repo_timestamp", "repo_name", "timestamp"),
     )
 
 
+class SubmoduleCommit(Base):
+    """Submodule commit record for monorepo aggregations.
+
+    Tracks individual submodule commits that are aggregated into
+    parent monorepo commits. Enables drill-down from aggregated
+    commit messages like "Monorepo: 2 commit(s)" to see the actual
+    commits.
+    """
+
+    __tablename__ = "submodule_commits"
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
+    parent_commit_hash: Mapped[str] = mapped_column(String(40), index=True)
+    submodule_name: Mapped[str] = mapped_column(String(255), index=True)
+    commit_hash: Mapped[str] = mapped_column(String(40))
+    commit_message: Mapped[str] = mapped_column(Text)
+    author: Mapped[Optional[str]] = mapped_column(String(255), nullable=True)
+    timestamp: Mapped[datetime] = mapped_column(DateTime, index=True)
+    files_changed: Mapped[Optional[int]] = mapped_column(Integer, nullable=True)
+    insertions: Mapped[Optional[int]] = mapped_column(Integer, nullable=True)
+    deletions: Mapped[Optional[int]] = mapped_column(Integer, nullable=True)
+    created_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow)
+
+    __table_args__ = (
+        Index("idx_submodule_commit_parent", "parent_commit_hash"),
+        Index("idx_submodule_commit_name", "submodule_name"),
+        Index("idx_submodule_commit_timestamp", "timestamp"),
+        Index("idx_submodule_commit_parent_name", "parent_commit_hash", "submodule_name"),
+    )
+
+
 class Cycle(Base):
     """Commit cycle execution record."""
 
@@ -42,6 +79,7 @@ class Cycle(Base):
 
     id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
     daemon_id: Mapped[str] = mapped_column(String(16), index=True)
+    hostname: Mapped[Optional[str]] = mapped_column(String(255), nullable=True, index=True)
     started_at: Mapped[datetime] = mapped_column(DateTime, index=True)
     completed_at: Mapped[Optional[datetime]] = mapped_column(DateTime, nullable=True)
     duration_seconds: Mapped[Optional[float]] = mapped_column(Float, nullable=True)
@@ -65,6 +103,7 @@ class Error(Base):
 
     id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
     daemon_id: Mapped[str] = mapped_column(String(16), index=True)
+    hostname: Mapped[Optional[str]] = mapped_column(String(255), nullable=True, index=True)
     repo_name: Mapped[str] = mapped_column(String(255), index=True)
     timestamp: Mapped[datetime] = mapped_column(DateTime, index=True)
     error_type: Mapped[str] = mapped_column(String(100), index=True)
@@ -79,6 +118,20 @@ class Error(Base):
     )
 
 
+class Deployment(Base):
+    """Deployment/upgrade tracking."""
+
+    __tablename__ = "deployments"
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
+    timestamp: Mapped[datetime] = mapped_column(DateTime, index=True)
+    version: Mapped[Optional[str]] = mapped_column(String(50), nullable=True)
+    commit_hash: Mapped[Optional[str]] = mapped_column(String(40), nullable=True)
+    notes: Mapped[Optional[str]] = mapped_column(Text, nullable=True)
+
+    __table_args__ = (Index("idx_deployment_timestamp", "timestamp"),)
+
+
 class RepositoryStatus(Base):
     """Repository status tracking."""
 
@@ -100,7 +153,7 @@ class RepositoryStatus(Base):
     total_commits: Mapped[int] = mapped_column(Integer, default=0)
     total_errors: Mapped[int] = mapped_column(Integer, default=0)
     consecutive_errors: Mapped[int] = mapped_column(Integer, default=0)
-    extra_data: Mapped[Optional[dict]] = mapped_column(JSON, nullable=True)
+    extra_data: Mapped[Optional[dict[str, Any]]] = mapped_column(JSON, nullable=True)
     updated_at: Mapped[datetime] = mapped_column(
         DateTime, default=datetime.utcnow, onupdate=datetime.utcnow
     )
diff --git a/src/auto_commit_service/database/repository.py b/src/auto_commit_service/database/repository.py
index 27d426b..da68a22 100644
--- a/src/auto_commit_service/database/repository.py
+++ b/src/auto_commit_service/database/repository.py
@@ -7,7 +7,7 @@ from typing import List, Optional
 from sqlalchemy import select, func, and_, or_
 from sqlalchemy.ext.asyncio import AsyncSession
 
-from .models import Commit, Cycle, Error, RepositoryStatus
+from .models import Commit, Cycle, Deployment, Error, RepositoryStatus
 
 logger = logging.getLogger(__name__)
 
@@ -27,6 +27,7 @@ class CommitRepository:
         files_changed: Optional[int] = None,
         insertions: Optional[int] = None,
         deletions: Optional[int] = None,
+        hostname: Optional[str] = None,
     ) -> Commit:
         """Create a new commit record."""
         commit = Commit(
@@ -35,6 +36,7 @@ class CommitRepository:
             message=message,
             timestamp=timestamp,
             daemon_id=daemon_id,
+            hostname=hostname,
             branch=branch,
             files_changed=files_changed,
             insertions=insertions,
@@ -50,6 +52,7 @@ class CommitRepository:
         limit: int = 20,
         daemon_id: Optional[str] = None,
         repo_name: Optional[str] = None,
+        hostname: Optional[str] = None,
     ) -> List[Commit]:
         """Get recent commits, newest first."""
         query = select(Commit).order_by(Commit.timestamp.desc()).limit(limit)
@@ -58,6 +61,8 @@ class CommitRepository:
             query = query.where(Commit.daemon_id == daemon_id)
         if repo_name:
             query = query.where(Commit.repo_name == repo_name)
+        if hostname:
+            query = query.where(Commit.hostname == hostname)
 
         result = await session.execute(query)
         return list(result.scalars().all())
@@ -304,3 +309,81 @@ class RepositoryStatusRepository:
 
         result = await session.execute(query)
         return list(result.scalars().all())
+
+
+class DeploymentRepository:
+    """Repository for deployment/upgrade tracking."""
+
+    @staticmethod
+    async def record_deployment(
+        session: AsyncSession,
+        version: Optional[str] = None,
+        commit_hash: Optional[str] = None,
+        notes: Optional[str] = None,
+    ) -> Deployment:
+        """Record a new deployment/upgrade."""
+        deployment = Deployment(
+            timestamp=datetime.utcnow(),
+            version=version,
+            commit_hash=commit_hash,
+            notes=notes,
+        )
+        session.add(deployment)
+        await session.flush()
+        return deployment
+
+    @staticmethod
+    async def get_last_deployment(
+        session: AsyncSession,
+    ) -> Optional[Deployment]:
+        """Get the most recent deployment."""
+        query = (
+            select(Deployment)
+            .order_by(Deployment.timestamp.desc())
+            .limit(1)
+        )
+        result = await session.execute(query)
+        return result.scalar_one_or_none()
+
+    @staticmethod
+    async def get_deployments(
+        session: AsyncSession,
+        limit: int = 10,
+    ) -> List[Deployment]:
+        """Get recent deployments."""
+        query = (
+            select(Deployment)
+            .order_by(Deployment.timestamp.desc())
+            .limit(limit)
+        )
+        result = await session.execute(query)
+        return list(result.scalars().all())
+
+    @staticmethod
+    async def get_commits_since_deployment(
+        session: AsyncSession,
+        deployment_id: Optional[int] = None,
+    ) -> List[Commit]:
+        """Get all commits since the specified deployment (or last deployment if not specified)."""
+        # Get deployment timestamp
+        if deployment_id:
+            deployment_query = select(Deployment).where(Deployment.id == deployment_id)
+            deployment_result = await session.execute(deployment_query)
+            deployment = deployment_result.scalar_one_or_none()
+        else:
+            deployment = await DeploymentRepository.get_last_deployment(session)
+
+        if not deployment:
+            # No deployment recorded, return all commits
+            commits_query = select(Commit).order_by(Commit.timestamp.desc())
+            commits_result = await session.execute(commits_query)
+            return list(commits_result.scalars().all())
+
+        # Get commits since deployment
+        commits_query = (
+            select(Commit)
+            .where(Commit.timestamp >= deployment.timestamp)
+            .order_by(Commit.timestamp.desc())
+        )
+        commits_result = await session.execute(commits_query)
+        return list(commits_result.scalars().all())
diff --git a/src/auto_commit_service/git/__init__.py b/src/auto_commit_service/git/__init__.py
index ca0ebe6..dce88ba 100644
--- a/src/auto_commit_service/git/__init__.py
+++ b/src/auto_commit_service/git/__init__.py
@@ -13,6 +13,17 @@ from .operations import (
 )
 from .diff_parser import summarize_diff, DiffSummary
 from .discovery import discover_git_repos
+from .submodules import (
+    SubmoduleInfo,
+    SubmoduleCommitResult,
+    has_submodules,
+    parse_gitmodules,
+    get_submodule_status,
+    get_dirty_submodules,
+    get_submodule_head,
+    stage_submodule_reference,
+    get_submodule_remote_and_branch,
+)
 
 __all__ = [
     "Repository",
@@ -27,4 +38,14 @@ __all__ = [
     "summarize_diff",
     "DiffSummary",
     "discover_git_repos",
+    # Submodule support
+    "SubmoduleInfo",
+    "SubmoduleCommitResult",
+    "has_submodules",
+    "parse_gitmodules",
+    "get_submodule_status",
+    "get_dirty_submodules",
+    "get_submodule_head",
+    "stage_submodule_reference",
+    "get_submodule_remote_and_branch",
 ]
diff --git a/src/auto_commit_service/git/operations.py b/src/auto_commit_service/git/operations.py
index 00fb2e0..6f2a760 100644
--- a/src/auto_commit_service/git/operations.py
+++ b/src/auto_commit_service/git/operations.py
@@ -9,6 +9,13 @@ from .repository import GitStatus, CommitResult, PushResult
 logger = logging.getLogger(__name__)
 
 
+def unquote_git_path(path: str) -> str:
+    """Strip git's porcelain quoting from paths with spaces/special chars."""
+    if path.startswith('"') and path.endswith('"'):
+        return path[1:-1]
+    return path
+
+
 class GitError(Exception):
     """Base exception for git operations."""
 
@@ -118,7 +125,7 @@ async def git_status(repo_path: Path) -> GitStatus:
         if len(line) >= 3:
             index_status = line[0]
             worktree_status = line[1]
-            filepath = line[3:]
+            filepath = unquote_git_path(line[3:])
 
             if index_status == "?" and worktree_status == "?":
                 untracked.append(filepath)
diff --git a/src/auto_commit_service/git/repository.py b/src/auto_commit_service/git/repository.py
index f612a61..a701c8e 100644
--- a/src/auto_commit_service/git/repository.py
+++ b/src/auto_commit_service/git/repository.py
@@ -26,8 +26,12 @@ class Repository:
 
     @property
     def exists(self) -> bool:
-        """Check if the repository exists."""
-        return self.path.exists() and self.git_dir.exists()
+        """Check if the repository exists.
+
+        Supports both regular repos (.git is a directory) and
+        submodules (.git is a gitlink file).
+        """
+        return self.path.exists() and (self.git_dir.is_dir() or self.git_dir.is_file())
 
     def __str__(self) -> str:
         return f"Repository({self.name} @ {self.path})"
diff --git a/src/auto_commit_service/git/submodules.py b/src/auto_commit_service/git/submodules.py
new file mode 100644
index 0000000..dc10ae7
--- /dev/null
+++ b/src/auto_commit_service/git/submodules.py
@@ -0,0 +1,212 @@
+"""Submodule detection and status querying for monorepo support.
+
+Provides primitives for detecting git submodules, checking their dirty state,
+and staging submodule reference updates in parent repositories.
+"""
+
+import configparser
+import logging
+from dataclasses import dataclass, field
+from pathlib import Path
+
+from .operations import _run_git_command, unquote_git_path
+
+logger = logging.getLogger(__name__)
+
+
+@dataclass
+class SubmoduleInfo:
+    """Information about a git submodule."""
+
+    name: str
+    path: str
+    url: str
+    current_hash: str | None = None
+    is_dirty: bool = False
+    has_untracked: bool = False
+    branch: str | None = None
+
+
+@dataclass
+class SubmoduleCommitResult:
+    """Result of committing within a submodule."""
+
+    submodule_name: str
+    submodule_path: str
+    success: bool
+    commit_hashes: list[str] = field(default_factory=list)
+    push_success: bool = False
+    error: str | None = None
+    new_hash: str | None = None
+
+
+def has_submodules(repo_path: Path) -> bool:
+    """Check if a repository uses submodules.
+
+    Quick synchronous check for .gitmodules file existence.
+    """
+    return (repo_path / ".gitmodules").is_file()
+
+
+def parse_gitmodules(repo_path: Path) -> list[SubmoduleInfo]:
+    """Parse .gitmodules file to extract submodule definitions.
+
+    Uses configparser since .gitmodules follows INI-like format:
+        [submodule "name"]
+            path = relative/path
+            url = git@host:org/repo.git
+            branch = main
+    """
+    gitmodules_path = repo_path / ".gitmodules"
+    if not gitmodules_path.exists():
+        return []
+
+    config = configparser.ConfigParser()
+    config.read(str(gitmodules_path))
+
+    submodules: list[SubmoduleInfo] = []
+    for section in config.sections():
+        if section.startswith('submodule "') and section.endswith('"'):
+            name = section[len('submodule "'):-1]
+        elif section.startswith("submodule "):
+            name = section[len("submodule "):]
+        else:
+            continue
+
+        path = config.get(section, "path", fallback=name)
+        url = config.get(section, "url", fallback="")
+        branch = config.get(section, "branch", fallback=None)
+
+        submodules.append(SubmoduleInfo(
+            name=name,
+            path=path,
+            url=url,
+            branch=branch,
+        ))
+
+    return submodules
+
+
+async def get_submodule_status(repo_path: Path) -> list[SubmoduleInfo]:
+    """Get status of all submodules including dirty state.
+
+    Combines `git submodule status` (parent perspective) with
+    `git status --porcelain` (internal check) to determine which
+    submodules have uncommitted changes.
+    """
+    submodules = parse_gitmodules(repo_path)
+    if not submodules:
+        return []
+
+    # Get current hash and modification status from parent perspective
+    stdout, _, returncode = await _run_git_command(
+        "submodule", "status", cwd=repo_path, check=False
+    )
+
+    # Parse output lines:
+    #   " <hash> <path> (<describe>)"  → clean
+    #   "+<hash> <path> (<describe>)"  → different commit than parent tracks
+    #   "-<hash> <path>"               → not initialized
+    hash_map: dict[str, tuple[str, bool]] = {}
+    if returncode == 0 and stdout:
+        for line in stdout.splitlines():
+            if not line.strip():
+                continue
+            dirty_marker = line[0] if line else " "
+            parts = line[1:].strip().split(None, 2)
+            if len(parts) >= 2:
+                commit_hash = parts[0]
+                sm_path = parts[1]
+                hash_map[sm_path] = (commit_hash, dirty_marker == "+")
+
+    # Check parent's porcelain status for modified submodule paths
+    status_stdout, _, _ = await _run_git_command(
+        "status", "--porcelain", cwd=repo_path, check=False
+    )
+
+    dirty_paths: set[str] = set()
+    if status_stdout:
+        for line in status_stdout.splitlines():
+            if not line or len(line) < 3:
+                continue
+            filepath = unquote_git_path(line[3:].strip())
+            for sm in submodules:
+                if filepath == sm.path or filepath.startswith(sm.path + "/"):
+                    dirty_paths.add(sm.path)
+
+    # Populate each submodule's status
+    for sm in submodules:
+        sm_abs_path = repo_path / sm.path
+        if not sm_abs_path.exists():
+            continue
+
+        if sm.path in hash_map:
+            sm.current_hash, _ = hash_map[sm.path]
+
+        if sm.path in dirty_paths:
+            sm.is_dirty = True
+        else:
+            # Check internally for uncommitted changes
+            internal_stdout, _, rc = await _run_git_command(
+                "status", "--porcelain", cwd=sm_abs_path, check=False
+            )
+            if rc == 0 and internal_stdout.strip():
+                sm.is_dirty = True
+                sm.has_untracked = "??" in internal_stdout
+
+    return submodules
+
+
+async def get_dirty_submodules(repo_path: Path) -> list[SubmoduleInfo]:
+    """Get only submodules that have uncommitted changes."""
+    all_subs = await get_submodule_status(repo_path)
+    return [sm for sm in all_subs if sm.is_dirty]
+
+
+async def get_submodule_head(repo_path: Path, submodule_path: str) -> str | None:
+    """Get the current HEAD commit hash of a submodule."""
+    sm_abs = repo_path / submodule_path
+    stdout, _, rc = await _run_git_command(
+        "rev-parse", "HEAD", cwd=sm_abs, check=False
+    )
+    return stdout.strip() if rc == 0 and stdout else None
+
+
+async def stage_submodule_reference(repo_path: Path, submodule_path: str) -> None:
+    """Stage a submodule reference update in the parent repo.
+
+    Equivalent to `git add <submodule_path>` in the parent.
+    """
+    await _run_git_command("add", submodule_path, cwd=repo_path)
+
+
+async def get_submodule_remote_and_branch(
+    repo_path: Path, submodule_path: str
+) -> tuple[str, str]:
+    """Get the remote and branch for a submodule.
+
+    Checks the submodule's own git config, falling back to 'origin' and 'main'.
+    """
+    sm_abs = repo_path / submodule_path
+
+    # Get remote name
+    remote_stdout, _, rc = await _run_git_command(
+        "remote", cwd=sm_abs, check=False
+    )
+    remote = (
+        remote_stdout.strip().split("\n")[0]
+        if (rc == 0 and remote_stdout.strip())
+        else "origin"
+    )
+
+    # Get current branch
+    branch_stdout, _, rc = await _run_git_command(
+        "symbolic-ref", "--short", "HEAD", cwd=sm_abs, check=False
+    )
+    branch = (
+        branch_stdout.strip()
+        if (rc == 0 and branch_stdout.strip())
+        else "main"
+    )
+
+    return remote, branch
diff --git a/src/auto_commit_service/service/__init__.py b/src/auto_commit_service/service/__init__.py
deleted file mode 100644
index f50258f..0000000
--- a/src/auto_commit_service/service/__init__.py
+++ /dev/null
@@ -1,15 +0,0 @@
-"""Service lifecycle management."""
-
-from .manager import (
-    LlamaServiceManager,
-    ServiceHealth,
-    ServiceManagerError,
-    ServiceStartError,
-)
-
-__all__ = [
-    "LlamaServiceManager",
-    "ServiceHealth",
-    "ServiceManagerError",
-    "ServiceStartError",
-]
diff --git a/src/auto_commit_service/service/manager.py b/src/auto_commit_service/service/manager.py
deleted file mode 100644
index 3f81d74..0000000
--- a/src/auto_commit_service/service/manager.py
+++ /dev/null
@@ -1,327 +0,0 @@
-"""Llama service lifecycle manager."""
-
-import asyncio
-import fcntl
-import logging
-import os
-import signal
-import sys
-import time
-from enum import Enum
-from pathlib import Path
-
-import httpx
-
-logger = logging.getLogger(__name__)
-
-
-class ServiceManagerError(Exception):
-    """Base exception for service manager errors."""
-
-
-class ServiceStartError(ServiceManagerError):
-    """Failed to start service."""
-
-
-class ServiceHealth(str, Enum):
-    """Service health status."""
-
-    HEALTHY = "healthy"
-    CRASHED = "crashed"
-    UNREACHABLE = "unreachable"
-
-
-class LlamaServiceManager:
-    """Manages llama service lifecycle as subprocess."""
-
-    def __init__(
-        self,
-        service_url: str = "http://localhost:8000",
-        pid_file: Path | None = None,
-        lock_file: Path | None = None,
-        startup_timeout: float = 30.0,
-        health_check_timeout: float = 5.0,
-        model_id: str | None = None,
-        use_model_boss: bool = False,
-    ):
-        self.service_url = service_url
-        self._pid_file = pid_file or Path.home() / ".config/commits/llama-service.pid"
-        self._lock_file = lock_file or Path.home() / ".config/commits/llama-service.lock"
-        self._startup_timeout = startup_timeout
-        self._health_check_timeout = health_check_timeout
-        self._model_id = model_id
-        self._use_model_boss = use_model_boss
-        self._spawned_pid: int | None = None
-        self._lock_fd: int | None = None
-        self._resolved_model_path: str | None = None
-
-    async def ensure_service_available(self) -> bool:
-        """Ensure service is available, starting if necessary."""
-        health = await self.check_health()
-
-        if health == ServiceHealth.HEALTHY:
-            return True
-        if health == ServiceHealth.CRASHED:
-            logger.info("Detected crashed service (stale PID), cleaning up...")
-            self._cleanup_pid_file()
-
-        logger.info("Llama service unreachable, attempting to start...")
-
-        try:
-            if self._use_model_boss and self._model_id:
-                await self._resolve_model_path()
-            return await self.start_service()
-        except ServiceStartError as e:
-            logger.error(f"Failed to start llama-service: {e}")
-            return False
-
-    async def _resolve_model_path(self) -> None:
-        """Resolve model ID to path via model-boss."""
-        try:
-            from lilith_model_boss import ensure_model
-
-            if self._model_id and not self._resolved_model_path:
-                logger.info(f"Resolving model via model-boss: {self._model_id}")
-                self._resolved_model_path = ensure_model(self._model_id)
-                logger.info(f"Resolved model path: {self._resolved_model_path}")
-        except ImportError:
-            raise ServiceStartError("model-boss not installed")
-        except Exception as e:
-            raise ServiceStartError(f"Failed to resolve model path: {e}")
-
-    async def start_service(self) -> bool:
-        """Start llama service subprocess."""
-        pid = self._read_pid_file()
-        if pid and self._is_process_alive(pid):
-            logger.info(f"Service already running (PID: {pid})")
-            return True
-
-        if not self._acquire_lock():
-            await asyncio.sleep(2)
-            pid = self._read_pid_file()
-            if pid and self._is_process_alive(pid):
-                return True
-            return False
-
-        try:
-            pid = self._read_pid_file()
-            if pid and self._is_process_alive(pid):
-                return True
-
-            logger.info("Starting llama service subprocess...")
-            process = await self._spawn_service()
-            self._spawned_pid = process.pid
-            self._write_pid_file(process.pid)
-            logger.info(f"Llama service started (PID: {process.pid})")
-
-            if await self._wait_for_healthy(self._startup_timeout):
-                logger.info("✓ Llama service is healthy")
-                return True
-            else:
-                logger.error(f"✗ Service failed to start within {self._startup_timeout}s")
-                return False
-        except Exception as e:
-            logger.exception(f"Failed to start llama service: {e}")
-            return False
-        finally:
-            self._release_lock()
-
-    async def check_health(self) -> ServiceHealth:
-        """Check service health."""
-        pid = self._read_pid_file()
-        if pid and not self._is_process_alive(pid):
-            return ServiceHealth.CRASHED
-
-        try:
-            async with httpx.AsyncClient(timeout=self._health_check_timeout) as client:
-                response = await client.get(f"{self.service_url}/health")
-                if response.status_code == 200:
-                    data = response.json()
-                    return ServiceHealth.HEALTHY if data.get("status") == "ok" else ServiceHealth.UNREACHABLE
-                return ServiceHealth.UNREACHABLE
-        except (httpx.ConnectError, httpx.TimeoutException):
-            return ServiceHealth.UNREACHABLE
-        except Exception:
-            return ServiceHealth.UNREACHABLE
-
-    async def stop_service(self) -> None:
-        """Gracefully stop service if we own it."""
-        if self._spawned_pid is None or not self._is_process_alive(self._spawned_pid):
-            return
-
-        logger.info(f"Stopping llama service (PID: {self._spawned_pid})...")
-        try:
-            os.kill(self._spawned_pid, signal.SIGTERM)
-            for _ in range(10):
-                if not self._is_process_alive(self._spawned_pid):
-                    self._cleanup_pid_file()
-                    return
-                await asyncio.sleep(0.5)
-            os.kill(self._spawned_pid, signal.SIGKILL)
-            self._cleanup_pid_file()
-        except ProcessLookupError:
-            self._cleanup_pid_file()
-        except Exception as e:
-            logger.exception(f"Error stopping service: {e}")
-
-    def _acquire_lock(self) -> bool:
-        self._lock_file.parent.mkdir(parents=True, exist_ok=True)
-        try:
-            self._lock_fd = os.open(self._lock_file, os.O_CREAT | os.O_WRONLY)
-            fcntl.flock(self._lock_fd, fcntl.LOCK_EX | fcntl.LOCK_NB)
-            return True
-        except BlockingIOError:
-            return False
-
-    def _release_lock(self) -> None:
-        if self._lock_fd is not None:
-            try:
-                fcntl.flock(self._lock_fd, fcntl.LOCK_UN)
-                os.close(self._lock_fd)
-                self._lock_fd = None
-            except Exception:
-                pass
-
-    def _read_pid_file(self) -> int | None:
-        if not self._pid_file.exists():
-            return None
-        try:
-            content = self._pid_file.read_text().strip()
-            return int(content) if content else None
-        except Exception:
-            return None
-
-    def _write_pid_file(self, pid: int) -> None:
-        self._pid_file.parent.mkdir(parents=True, exist_ok=True)
-        self._pid_file.write_text(str(pid))
-
-    def _cleanup_pid_file(self) -> None:
-        try:
-            if self._pid_file.exists():
-                self._pid_file.unlink()
-        except Exception:
-            pass
-
-    def _is_process_alive(self, pid: int) -> bool:
-        try:
-            os.kill(pid, 0)
-            return True
-        except OSError:
-            return False
-
-    def _find_default_model(self) -> str | None:
-        """Find a suitable model in standard cache locations."""
-        cache_dir = Path.home() / ".cache" / "models"
-        if not cache_dir.exists():
-            return None
-
-        preferred = [
-            "qwen2.5-1.5b-instruct-q4_k_m.gguf",
-            "Ministral-3-3B-Instruct-2512-Q8_0.gguf",
-        ]
-
-        for name in preferred:
-            path = cache_dir / name
-            if path.exists():
-                return str(path)
-
-        for gguf in cache_dir.glob("*.gguf"):
-            if gguf.stat().st_size < 5 * 1024 * 1024 * 1024:
-                return str(gguf)
-
-        return None
-
-    def _find_python_with_module(self, module_name: str) -> str:
-        """Find a Python executable that can import the given module.
-
-        Tries multiple Python paths to find one with access to user-installed packages.
-        This handles the case where sys.executable is /usr/bin/python (system Python)
-        but packages are installed in user site-packages.
-        """
-        import shutil
-        import subprocess
-
-        candidates = [
-            str(Path.home() / ".local" / "bin" / "python"),
-            str(Path.home() / ".local" / "bin" / "python3"),
-            shutil.which("python3"),
-            shutil.which("python"),
-            sys.executable,
-        ]
-
-        for python_path in candidates:
-            if not python_path or not Path(python_path).exists():
-                continue
-
-            try:
-                result = subprocess.run(
-                    [python_path, "-c", f"import {module_name}"],
-                    capture_output=True,
-                    timeout=5,
-                )
-                if result.returncode == 0:
-                    logger.info(f"Found Python with {module_name}: {python_path}")
-                    return python_path
-            except (subprocess.TimeoutExpired, FileNotFoundError, PermissionError):
-                continue
-
-        logger.warning(f"Could not find Python with {module_name}, using {sys.executable}")
-        return sys.executable
-
-    async def _spawn_service(self) -> asyncio.subprocess.Process:
-        """Spawn service subprocess."""
-        python_path = self._find_python_with_module("llama_http")
-        cmd = [python_path, "-m", "llama_http"]
-        env = os.environ.copy()
-
-        model_path = self._resolved_model_path or env.get("LLAMA_SERVICE_MODEL_PATH")
-
-        if not model_path:
-            model_path = self._find_default_model()
-
-        if not model_path:
-            raise ServiceStartError(
-                "No model found. Either:\n"
-                "  1. Set LLAMA_SERVICE_MODEL_PATH\n"
-                "  2. Place a GGUF model in ~/.cache/models/"
-            )
-
-        # Configure environment for llama-http service
-        # Note: llama-http uses LLAMA_HTTP_ prefix for env vars
-        env["LLAMA_HTTP_MODEL_PATH"] = model_path
-        # Extract port from service_url and configure llama-http to use it
-        from urllib.parse import urlparse
-        port = urlparse(self.service_url).port or 8000
-        env["LLAMA_HTTP_PORT"] = str(port)
-        logger.info(f"Using model: {model_path}, port: {port}")
-
-        log_file = self._pid_file.parent / "llama-service.log"
-        log_file.parent.mkdir(parents=True, exist_ok=True)
-
-        with open(log_file, "a") as log:
-            log.write(f"\n=== Service started at {time.ctime()} ===\n")
-            log.write(f"Model: {model_path}\n")
-
-            process = await asyncio.create_subprocess_exec(
-                *cmd,
-                env=env,
-                stdout=log,
-                stderr=asyncio.subprocess.STDOUT,
-                start_new_session=True,
-            )
-        return process
-
-    async def _wait_for_healthy(self, timeout: float) -> bool:
-        start = time.time()
-        while time.time() - start < timeout:
-            try:
-                async with httpx.AsyncClient(timeout=2.0) as client:
-                    response = await client.get(f"{self.service_url}/health")
-                    if response.status_code == 200:
-                        data = response.json()
-                        if data.get("status") == "ok":
-                            return True
-            except Exception:
-                pass
-            await asyncio.sleep(1)
-        return False
diff --git a/src/auto_commit_service/services/__init__.py b/src/auto_commit_service/services/__init__.py
new file mode 100644
index 0000000..f0f08bd
--- /dev/null
+++ b/src/auto_commit_service/services/__init__.py
@@ -0,0 +1,5 @@
+"""Services for auto-commit system."""
+
+from .submodule_commit_service import SubmoduleCommitService
+
+__all__ = ["SubmoduleCommitService"]
diff --git a/src/auto_commit_service/services/submodule_commit_service.py b/src/auto_commit_service/services/submodule_commit_service.py
new file mode 100644
index 0000000..73c0926
--- /dev/null
+++ b/src/auto_commit_service/services/submodule_commit_service.py
@@ -0,0 +1,226 @@
+"""Service for persisting and retrieving submodule commit details."""
+
+import logging
+import re
+import subprocess
+from dataclasses import dataclass
+from datetime import datetime
+from pathlib import Path
+
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from ..activity_log import ActionType, ActivityLogger
+from ..database.models import SubmoduleCommit
+from ..git.submodules import SubmoduleCommitResult
+
+logger = logging.getLogger(__name__)
+
+
+@dataclass
+class CommitStats:
+    """Statistics about a commit."""
+
+    files: int
+    insertions: int
+    deletions: int
+
+
+@dataclass
+class CommitDetails:
+    """Detailed information about a single commit."""
+
+    hash: str
+    author: str
+    email: str
+    timestamp: datetime
+    message: str
+    stats: CommitStats
+
+
+class SubmoduleCommitService:
+    """Service for persisting and retrieving submodule commit details.
+
+    Captures individual commit information from submodule processing so it can
+    be displayed when viewing monorepo aggregated commits.
+    """
+
+    def __init__(self, activity_log: ActivityLogger) -> None:
+        """Initialize submodule commit service.
+
+        Args:
+            activity_log: Activity logger for audit trail
+        """
+        self.activity_log = activity_log
+
+    async def persist_submodule_commits(
+        self,
+        session: AsyncSession,
+        parent_commit_hash: str,
+        submodule_results: list[SubmoduleCommitResult],
+    ) -> int:
+        """Persist submodule commits to database and activity log.
+
+        Args:
+            session: Database session
+            parent_commit_hash: Hash of parent monorepo commit
+            submodule_results: List of submodule commit results
+
+        Returns:
+            Number of submodule commits persisted
+        """
+        persisted_count = 0
+
+        for result in submodule_results:
+            if not result.success or not result.commit_hashes:
+                continue
+
+            for commit_hash in result.commit_hashes:
+                try:
+                    # Get commit details from git
+                    details = await self._get_commit_details(
+                        submodule_path=result.submodule_path,
+                        commit_hash=commit_hash,
+                    )
+
+                    # Create database record
+                    submodule_commit = SubmoduleCommit(
+                        parent_commit_hash=parent_commit_hash,
+                        submodule_name=result.submodule_name,
+                        commit_hash=details.hash,
+                        commit_message=details.message,
+                        author=details.author,
+                        timestamp=details.timestamp,
+                        files_changed=details.stats.files,
+                        insertions=details.stats.insertions,
+                        deletions=details.stats.deletions,
+                    )
+
+                    session.add(submodule_commit)
+                    persisted_count += 1
+
+                    # Activity log for audit trail
+                    self.activity_log.log(
+                        ActionType.SUBMODULE_COMMIT,
+                        {
+                            "parent_commit": parent_commit_hash,
+                            "submodule": result.submodule_name,
+                            "hash": details.hash,
+                            "message": details.message,
+                            "author": details.author,
+                            "stats": {
+                                "files": details.stats.files,
+                                "insertions": details.stats.insertions,
+                                "deletions": details.stats.deletions,
+                            },
+                        },
+                    )
+
+                except Exception as e:
+                    logger.error(
+                        f"Failed to persist submodule commit {commit_hash} "
+                        f"for {result.submodule_name}: {e}"
+                    )
+
+        await session.flush()
+        return persisted_count
+
+    async def get_submodule_commits(
+        self, session: AsyncSession, parent_commit_hash: str
+    ) -> list[SubmoduleCommit]:
+        """Retrieve submodule commits for a parent commit.
+
+        Args:
+            session: Database session
+            parent_commit_hash: Hash of parent monorepo commit
+
+        Returns:
+            List of submodule commits ordered by submodule name and timestamp
+        """
+        result = await session.execute(
+            select(SubmoduleCommit)
+            .where(SubmoduleCommit.parent_commit_hash == parent_commit_hash)
+            .order_by(SubmoduleCommit.submodule_name, SubmoduleCommit.timestamp)
+        )
+        return list(result.scalars().all())
+
+    async def _get_commit_details(
+        self, submodule_path: str, commit_hash: str
+    ) -> CommitDetails:
+        """Extract commit details using git show.
+
+        Args:
+            submodule_path: Path to submodule
+            commit_hash: Commit hash to inspect
+
+        Returns:
+            CommitDetails with all extracted information
+        """
+        # Resolve absolute path
+        path = Path(submodule_path).resolve()
+
+        # Get commit metadata and stats
+        result = subprocess.run(
+            [
+                "git",
+                "-C",
+                str(path),
+                "show",
+                commit_hash,
+                "--format=%H|%an|%ae|%at|%s",
+                "--shortstat",
+            ],
+            capture_output=True,
+            text=True,
+            check=True,
+        )
+
+        return self._parse_commit_details(result.stdout)
+
+    def _parse_commit_details(self, git_output: str) -> CommitDetails:
+        """Parse git show output into structured CommitDetails.
+
+        Args:
+            git_output: Output from git show command
+
+        Returns:
+            Parsed CommitDetails
+        """
+        lines = git_output.strip().split("\n")
+
+        # First line: hash|author|email|timestamp|subject
+        metadata = lines[0].split("|", 4)
+        commit_hash = metadata[0]
+        author = metadata[1]
+        email = metadata[2]
+        timestamp = datetime.fromtimestamp(int(metadata[3]))
+        subject = metadata[4] if len(metadata) > 4 else ""
+
+        # Find shortstat line (e.g., "3 files changed, 45 insertions(+), 12 deletions(-)")
+        stats = CommitStats(files=0, insertions=0, deletions=0)
+
+        for line in lines[1:]:
+            if "changed" in line or "insertion" in line or "deletion" in line:
+                # Parse shortstat
+                files_match = re.search(r"(\d+) files? changed", line)
+                if files_match:
+                    stats.files = int(files_match.group(1))
+
+                insertions_match = re.search(r"(\d+) insertion", line)
+                if insertions_match:
+                    stats.insertions = int(insertions_match.group(1))
+
+                deletions_match = re.search(r"(\d+) deletion", line)
+                if deletions_match:
+                    stats.deletions = int(deletions_match.group(1))
+
+                break
+
+        return CommitDetails(
+            hash=commit_hash,
+            author=author,
+            email=email,
+            timestamp=timestamp,
+            message=subject,
+            stats=stats,
+        )