chore: migrate module path from git.t-juice.club to code.t-juice.club

Update Go module path and all import references for Gitea to Forgejo host migration. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
feat: add optional basic auth support for Loki client
2026-03-09 19:48:25 +01:00 · 2026-02-17 20:32:10 +01:00 · 2026-02-13 22:22:08 +01:00 · 2026-02-13 22:20:48 +01:00 · 2026-02-13 22:12:08 +01:00 · 2026-02-08 03:30:29 +00:00
34 changed files with 3298 additions and 98 deletions
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -25,6 +25,13 @@ Query Prometheus metrics, Alertmanager alerts, and Loki logs. Unlike other serve
 - 8 core tools: list/get alerts, search metrics, get metadata, PromQL query, list targets, list/create silences
 - 3 optional Loki tools (when `LOKI_URL` is set): query_logs, list_labels, list_label_values
 - Configurable Prometheus, Alertmanager, and Loki URLs via flags or environment variables
+- Optional basic auth for Loki (`LOKI_USERNAME`/`LOKI_PASSWORD`)
+
+### Git Explorer (`git-explorer`)
+Read-only access to git repository information. Designed for deployment verification.
+- 9 tools: resolve_ref, get_log, get_commit_info, get_diff_files, get_file_at_commit, is_ancestor, commits_between, list_branches, search_commits
+- Uses go-git library for pure Go implementation
+- All operations are read-only (never modifies repository)

 The nixpkgs/options/hm servers share a database-backed architecture:
 - Full-text search across option/package names and descriptions
@@ -39,7 +46,7 @@ The nixpkgs/options/hm servers share a database-backed architecture:
 - **Build System**: Nix flakes
 - **Databases**: PostgreSQL and SQLite (both fully supported)
 - **Protocol**: MCP (Model Context Protocol) - JSON-RPC over STDIO or HTTP/SSE
- **Module Path**: `git.t-juice.club/torjus/labmcp`
+- **Module Path**: `code.t-juice.club/torjus/labmcp`

 ## Project Status

@@ -62,8 +69,10 @@ labmcp/
 │   │   └── main.go             # NixOS options CLI (legacy)
 │   ├── hm-options/
 │   │   └── main.go             # Home Manager options CLI
-│   └── lab-monitoring/
-│       └── main.go             # Prometheus/Alertmanager CLI
+│   ├── lab-monitoring/
+│   │   └── main.go             # Prometheus/Alertmanager CLI
+│   └── git-explorer/
+│       └── main.go             # Git repository explorer CLI
 ├── internal/
 │   ├── database/
 │   │   ├── interface.go        # Store interface (options + packages)
@@ -96,18 +105,26 @@ labmcp/
 │   │   ├── parser.go           # nix-env JSON parsing
 │   │   ├── types.go            # Package types, channel aliases
 │   │   └── *_test.go           # Parser tests
-│   └── monitoring/
-│       ├── types.go            # Prometheus/Alertmanager/Loki API types
-│       ├── prometheus.go       # Prometheus HTTP client
-│       ├── alertmanager.go     # Alertmanager HTTP client
-│       ├── loki.go             # Loki HTTP client
+│   ├── monitoring/
+│   │   ├── types.go            # Prometheus/Alertmanager/Loki API types
+│   │   ├── prometheus.go       # Prometheus HTTP client
+│   │   ├── alertmanager.go     # Alertmanager HTTP client
+│   │   ├── loki.go             # Loki HTTP client
+│   │   ├── handlers.go         # MCP tool definitions + handlers
+│   │   ├── format.go           # Markdown formatting utilities
+│   │   └── *_test.go           # Tests (httptest-based)
+│   └── gitexplorer/
+│       ├── client.go           # go-git repository wrapper
+│       ├── types.go            # Type definitions
 │       ├── handlers.go         # MCP tool definitions + handlers
-│       ├── format.go           # Markdown formatting utilities
-│       └── *_test.go           # Tests (httptest-based)
+│       ├── format.go           # Markdown formatters
+│       ├── validation.go       # Path validation
+│       └── *_test.go           # Tests
 ├── nix/
 │   ├── module.nix                  # NixOS module for nixos-options
 │   ├── hm-options-module.nix       # NixOS module for hm-options
 │   ├── lab-monitoring-module.nix   # NixOS module for lab-monitoring
+│   ├── git-explorer-module.nix     # NixOS module for git-explorer
 │   └── package.nix                 # Parameterized Nix package
 ├── testdata/
 │   └── options-sample.json     # Test fixture
@@ -128,7 +145,7 @@ labmcp/
 | `search_options` | Full-text search across option names and descriptions |
 | `get_option` | Get full details for a specific option with children |
 | `get_file` | Fetch source file contents from indexed repository |
-| `index_revision` | Index a revision (by hash or channel name) |
+| `index_revision` | Index a revision (options, files, and packages for nixpkgs) |
 | `list_revisions` | List all indexed revisions |
 | `delete_revision` | Delete an indexed revision |

@@ -139,6 +156,7 @@ labmcp/
 | `search_packages` | Full-text search across package names and descriptions |
 | `get_package` | Get full details for a specific package by attr path |
 | `get_file` | Fetch source file contents from nixpkgs |
+| `index_revision` | Index a revision to make its packages searchable |
 | `list_revisions` | List all indexed revisions |
 | `delete_revision` | Delete an indexed revision |

@@ -158,6 +176,20 @@ labmcp/
 | `list_labels` | List available label names from Loki (requires `LOKI_URL`) |
 | `list_label_values` | List values for a specific label from Loki (requires `LOKI_URL`) |

+### Git Explorer Server (git-explorer)
+
+| Tool | Description |
+|------|-------------|
+| `resolve_ref` | Resolve a git ref (branch, tag, commit) to its full commit hash |
+| `get_log` | Get commit log with optional filters (author, path, limit) |
+| `get_commit_info` | Get full details for a specific commit |
+| `get_diff_files` | Get list of files changed between two commits |
+| `get_file_at_commit` | Get file contents at a specific commit |
+| `is_ancestor` | Check if one commit is an ancestor of another |
+| `commits_between` | Get all commits between two refs |
+| `list_branches` | List all branches in the repository |
+| `search_commits` | Search commit messages for a pattern |
+
 ## Key Implementation Details

 ### Database
@@ -261,6 +293,20 @@ lab-monitoring labels                         # List Loki labels
 lab-monitoring labels --values job            # List values for a label
 ```

+### git-explorer
+```bash
+git-explorer serve                            # Run MCP server on STDIO
+git-explorer serve --transport http           # Run MCP server on HTTP
+git-explorer --repo /path resolve <ref>       # Resolve ref to commit hash
+git-explorer --repo /path log --limit 10      # Show commit log
+git-explorer --repo /path show <ref>          # Show commit details
+git-explorer --repo /path diff <from> <to>    # Files changed between commits
+git-explorer --repo /path cat <ref> <path>    # File contents at commit
+git-explorer --repo /path branches            # List branches
+git-explorer --repo /path search <query>      # Search commit messages
+git-explorer --version                        # Show version
+```
+
 ### Channel Aliases

 **nixpkgs-search/nixos-options**: `nixos-unstable`, `nixos-stable`, `nixos-24.11`, `nixos-24.05`, etc.
@@ -314,6 +360,7 @@ Each package's version is defined in multiple places that must stay in sync *for
 - **nixpkgs-search**: `cmd/nixpkgs-search/main.go` + `internal/mcp/server.go` (`DefaultNixOSConfig`, `DefaultNixpkgsPackagesConfig`)
 - **nixos-options**: `cmd/nixos-options/main.go` + `internal/mcp/server.go` (`DefaultNixOSConfig`)
 - **hm-options**: `cmd/hm-options/main.go` + `internal/mcp/server.go` (`DefaultHomeManagerConfig`)
+- **git-explorer**: `cmd/git-explorer/main.go` + `internal/mcp/server.go` (`DefaultGitExplorerConfig`)
 - **nix/package.nix**: Shared across all packages (bump to highest version when any package changes)

 ### User Preferences
@@ -341,6 +388,7 @@ nix build .#nixpkgs-search
 nix build .#nixos-options
 nix build .#hm-options
 nix build .#lab-monitoring
+nix build .#git-explorer

 # Run directly
 nix run .#nixpkgs-search -- options serve
@@ -349,6 +397,7 @@ nix run .#nixpkgs-search -- index nixos-unstable
 nix run .#hm-options -- serve
 nix run .#hm-options -- index hm-unstable
 nix run .#lab-monitoring -- serve
+nix run .#git-explorer -- --repo . serve
 ```

 ### Indexing Performance
--- a/README.md
+++ b/README.md
@@ -27,6 +27,20 @@ Query Prometheus metrics, Alertmanager alerts, and Loki logs from your monitorin
 - Manage alert silences
 - Query logs via LogQL (when Loki is configured)

+### Git Explorer (`git-explorer`)
+
+Read-only access to git repository information. Designed for deployment verification — comparing deployed flake revisions against source repositories.
+
+- Resolve refs (branches, tags, commits) to commit hashes
+- View commit logs with filtering by author, path, or range
+- Get full commit details including file change statistics
+- Compare commits to see which files changed
+- Read file contents at any commit
+- Check ancestry relationships between commits
+- Search commit messages
+
+All operations are read-only and will never modify the repository.
+
 ### NixOS Options (`nixos-options`) - Legacy

 Search and query NixOS configuration options. **Note**: Prefer using `nixpkgs-search` instead, which includes this functionality plus package search.
@@ -45,22 +59,25 @@ Search and query NixOS configuration options. **Note**: Prefer using `nixpkgs-se

 ```bash
 # Build the packages
-nix build git+https://git.t-juice.club/torjus/labmcp#nixpkgs-search
-nix build git+https://git.t-juice.club/torjus/labmcp#hm-options
-nix build git+https://git.t-juice.club/torjus/labmcp#lab-monitoring
+nix build git+https://code.t-juice.club/torjus/labmcp#nixpkgs-search
+nix build git+https://code.t-juice.club/torjus/labmcp#hm-options
+nix build git+https://code.t-juice.club/torjus/labmcp#lab-monitoring
+nix build git+https://code.t-juice.club/torjus/labmcp#git-explorer

 # Or run directly
-nix run git+https://git.t-juice.club/torjus/labmcp#nixpkgs-search -- --help
-nix run git+https://git.t-juice.club/torjus/labmcp#hm-options -- --help
-nix run git+https://git.t-juice.club/torjus/labmcp#lab-monitoring -- --help
+nix run git+https://code.t-juice.club/torjus/labmcp#nixpkgs-search -- --help
+nix run git+https://code.t-juice.club/torjus/labmcp#hm-options -- --help
+nix run git+https://code.t-juice.club/torjus/labmcp#lab-monitoring -- --help
+nix run git+https://code.t-juice.club/torjus/labmcp#git-explorer -- --help
 ```

 ### From Source

 ```bash
-go install git.t-juice.club/torjus/labmcp/cmd/nixpkgs-search@latest
-go install git.t-juice.club/torjus/labmcp/cmd/hm-options@latest
-go install git.t-juice.club/torjus/labmcp/cmd/lab-monitoring@latest
+go install code.t-juice.club/torjus/labmcp/cmd/nixpkgs-search@latest
+go install code.t-juice.club/torjus/labmcp/cmd/hm-options@latest
+go install code.t-juice.club/torjus/labmcp/cmd/lab-monitoring@latest
+go install code.t-juice.club/torjus/labmcp/cmd/git-explorer@latest
 ```

 ## Usage
@@ -99,7 +116,16 @@ Configure in your MCP client (e.g., Claude Desktop):
      "env": {
        "PROMETHEUS_URL": "http://prometheus.example.com:9090",
        "ALERTMANAGER_URL": "http://alertmanager.example.com:9093",
-        "LOKI_URL": "http://loki.example.com:3100"
+        "LOKI_URL": "http://loki.example.com:3100",
+        "LOKI_USERNAME": "optional-username",
+        "LOKI_PASSWORD": "optional-password"
+      }
+    },
+    "git-explorer": {
+      "command": "git-explorer",
+      "args": ["serve"],
+      "env": {
+        "GIT_REPO_PATH": "/path/to/your/repo"
      }
    }
  }
@@ -113,33 +139,40 @@ Alternatively, if you have Nix installed, you can use the flake directly without
  "mcpServers": {
    "nixpkgs-options": {
      "command": "nix",
-      "args": ["run", "git+https://git.t-juice.club/torjus/labmcp#nixpkgs-search", "--", "options", "serve"],
+      "args": ["run", "git+https://code.t-juice.club/torjus/labmcp#nixpkgs-search", "--", "options", "serve"],
      "env": {
        "NIXPKGS_SEARCH_DATABASE": "sqlite:///path/to/nixpkgs-search.db"
      }
    },
    "nixpkgs-packages": {
      "command": "nix",
-      "args": ["run", "git+https://git.t-juice.club/torjus/labmcp#nixpkgs-search", "--", "packages", "serve"],
+      "args": ["run", "git+https://code.t-juice.club/torjus/labmcp#nixpkgs-search", "--", "packages", "serve"],
      "env": {
        "NIXPKGS_SEARCH_DATABASE": "sqlite:///path/to/nixpkgs-search.db"
      }
    },
    "hm-options": {
      "command": "nix",
-      "args": ["run", "git+https://git.t-juice.club/torjus/labmcp#hm-options", "--", "serve"],
+      "args": ["run", "git+https://code.t-juice.club/torjus/labmcp#hm-options", "--", "serve"],
      "env": {
        "HM_OPTIONS_DATABASE": "sqlite:///path/to/hm-options.db"
      }
    },
    "lab-monitoring": {
      "command": "nix",
-      "args": ["run", "git+https://git.t-juice.club/torjus/labmcp#lab-monitoring", "--", "serve"],
+      "args": ["run", "git+https://code.t-juice.club/torjus/labmcp#lab-monitoring", "--", "serve"],
      "env": {
        "PROMETHEUS_URL": "http://prometheus.example.com:9090",
        "ALERTMANAGER_URL": "http://alertmanager.example.com:9093",
        "LOKI_URL": "http://loki.example.com:3100"
      }
+    },
+    "git-explorer": {
+      "command": "nix",
+      "args": ["run", "git+https://code.t-juice.club/torjus/labmcp#git-explorer", "--", "serve"],
+      "env": {
+        "GIT_REPO_PATH": "/path/to/your/repo"
+      }
    }
  }
 }
@@ -155,6 +188,7 @@ nixpkgs-search options serve --transport http
 nixpkgs-search packages serve --transport http
 hm-options serve --transport http
 lab-monitoring serve --transport http
+git-explorer serve --transport http

 # Custom address and CORS configuration
 nixpkgs-search options serve --transport http \
@@ -271,6 +305,35 @@ lab-monitoring labels
 lab-monitoring labels --values job
 ```

+**Git Explorer CLI:**
+
+```bash
+# Resolve a ref to commit hash
+git-explorer --repo /path/to/repo resolve main
+git-explorer --repo /path/to/repo resolve v1.0.0
+
+# View commit log
+git-explorer --repo /path/to/repo log --limit 10
+git-explorer --repo /path/to/repo log --author "John" --path src/
+
+# Show commit details
+git-explorer --repo /path/to/repo show HEAD
+git-explorer --repo /path/to/repo show abc1234
+
+# Compare commits
+git-explorer --repo /path/to/repo diff HEAD~5 HEAD
+
+# Show file at specific commit
+git-explorer --repo /path/to/repo cat HEAD README.md
+
+# List branches
+git-explorer --repo /path/to/repo branches
+git-explorer --repo /path/to/repo branches --remote
+
+# Search commit messages
+git-explorer --repo /path/to/repo search "fix bug"
+```
+
 **Delete an indexed revision:**

 ```bash
@@ -290,6 +353,8 @@ hm-options delete release-23.11
 | `PROMETHEUS_URL` | Prometheus base URL for lab-monitoring | `http://localhost:9090` |
 | `ALERTMANAGER_URL` | Alertmanager base URL for lab-monitoring | `http://localhost:9093` |
 | `LOKI_URL` | Loki base URL for lab-monitoring (optional, enables log tools) | *(none)* |
+| `LOKI_USERNAME` | Username for Loki basic auth (optional) | *(none)* |
+| `LOKI_PASSWORD` | Password for Loki basic auth (optional) | *(none)* |

 ### Database Connection Strings

@@ -323,7 +388,7 @@ hm-options -d "sqlite://my.db" index hm-unstable
 | `search_options` | Search for options by name or description |
 | `get_option` | Get full details for a specific option |
 | `get_file` | Fetch source file contents from the repository |
-| `index_revision` | Index a revision |
+| `index_revision` | Index a revision (options, files, and packages for nixpkgs) |
 | `list_revisions` | List all indexed revisions |
 | `delete_revision` | Delete an indexed revision |

@@ -334,7 +399,7 @@ hm-options -d "sqlite://my.db" index hm-unstable
 | `search_packages` | Search for packages by name or description |
 | `get_package` | Get full details for a specific package |
 | `get_file` | Fetch source file contents from nixpkgs |
-| `index_revision` | Index a revision |
+| `index_revision` | Index a revision to make its packages searchable |
 | `list_revisions` | List all indexed revisions |
 | `delete_revision` | Delete an indexed revision |

@@ -354,6 +419,20 @@ hm-options -d "sqlite://my.db" index hm-unstable
 | `list_labels` | List available label names from Loki (requires `LOKI_URL`) |
 | `list_label_values` | List values for a specific label from Loki (requires `LOKI_URL`) |

+### Git Explorer Server (git-explorer)
+
+| Tool | Description |
+|------|-------------|
+| `resolve_ref` | Resolve a git ref (branch, tag, commit) to its full commit hash |
+| `get_log` | Get commit log with optional filters (author, path, limit) |
+| `get_commit_info` | Get full details for a specific commit |
+| `get_diff_files` | Get list of files changed between two commits |
+| `get_file_at_commit` | Get file contents at a specific commit |
+| `is_ancestor` | Check if one commit is an ancestor of another |
+| `commits_between` | Get all commits between two refs |
+| `list_branches` | List all branches in the repository |
+| `search_commits` | Search commit messages for a pattern |
+
 ## NixOS Modules

 NixOS modules are provided for running the MCP servers as systemd services.
@@ -364,7 +443,7 @@ The `nixpkgs-search` module runs two separate MCP servers (options and packages)

 ```nix
 {
-  inputs.labmcp.url = "git+https://git.t-juice.club/torjus/labmcp";
+  inputs.labmcp.url = "git+https://code.t-juice.club/torjus/labmcp";

  outputs = { self, nixpkgs, labmcp }: {
    nixosConfigurations.myhost = nixpkgs.lib.nixosSystem {
@@ -401,7 +480,7 @@ The `nixpkgs-search` module runs two separate MCP servers (options and packages)

 ```nix
 {
-  inputs.labmcp.url = "git+https://git.t-juice.club/torjus/labmcp";
+  inputs.labmcp.url = "git+https://code.t-juice.club/torjus/labmcp";

  outputs = { self, nixpkgs, labmcp }: {
    nixosConfigurations.myhost = nixpkgs.lib.nixosSystem {
@@ -424,7 +503,7 @@ The `nixpkgs-search` module runs two separate MCP servers (options and packages)

 ```nix
 {
-  inputs.labmcp.url = "git+https://git.t-juice.club/torjus/labmcp";
+  inputs.labmcp.url = "git+https://code.t-juice.club/torjus/labmcp";

  outputs = { self, nixpkgs, labmcp }: {
    nixosConfigurations.myhost = nixpkgs.lib.nixosSystem {
@@ -445,11 +524,34 @@ The `nixpkgs-search` module runs two separate MCP servers (options and packages)
 }
 ```

+### git-explorer
+
+```nix
+{
+  inputs.labmcp.url = "git+https://code.t-juice.club/torjus/labmcp";
+
+  outputs = { self, nixpkgs, labmcp }: {
+    nixosConfigurations.myhost = nixpkgs.lib.nixosSystem {
+      system = "x86_64-linux";
+      modules = [
+        labmcp.nixosModules.git-explorer-mcp
+        {
+          services.git-explorer = {
+            enable = true;
+            repoPath = "/path/to/your/git/repo";
+          };
+        }
+      ];
+    };
+  };
+}
+```
+
 ### nixos-options (Legacy)

 ```nix
 {
-  inputs.labmcp.url = "git+https://git.t-juice.club/torjus/labmcp";
+  inputs.labmcp.url = "git+https://code.t-juice.club/torjus/labmcp";

  outputs = { self, nixpkgs, labmcp }: {
    nixosConfigurations.myhost = nixpkgs.lib.nixosSystem {
@@ -507,6 +609,8 @@ Both `options.http` and `packages.http` also support:
 | `prometheusUrl` | string | `"http://localhost:9090"` | Prometheus base URL |
 | `alertmanagerUrl` | string | `"http://localhost:9093"` | Alertmanager base URL |
 | `lokiUrl` | nullOr string | `null` | Loki base URL (enables log query tools when set) |
+| `lokiUsername` | nullOr string | `null` | Username for Loki basic authentication |
+| `lokiPasswordFile` | nullOr path | `null` | Path to file containing Loki password (uses systemd `LoadCredential`) |
 | `enableSilences` | bool | `false` | Enable the create_silence tool (write operation) |
 | `http.address` | string | `"127.0.0.1:8084"` | HTTP listen address |
 | `http.endpoint` | string | `"/mcp"` | HTTP endpoint path |
@@ -519,6 +623,25 @@ Both `options.http` and `packages.http` also support:

 The lab-monitoring module uses `DynamicUser=true`, so no separate user/group configuration is needed.

+#### git-explorer
+
+| Option | Type | Default | Description |
+|--------|------|---------|-------------|
+| `enable` | bool | `false` | Enable the service |
+| `package` | package | from flake | Package to use |
+| `repoPath` | string | *(required)* | Path to the git repository to serve |
+| `defaultRemote` | string | `"origin"` | Default remote name for ref resolution |
+| `http.address` | string | `"127.0.0.1:8085"` | HTTP listen address |
+| `http.endpoint` | string | `"/mcp"` | HTTP endpoint path |
+| `http.allowedOrigins` | list of string | `[]` | Allowed CORS origins |
+| `http.sessionTTL` | string | `"30m"` | Session timeout |
+| `http.tls.enable` | bool | `false` | Enable TLS |
+| `http.tls.certFile` | path | `null` | TLS certificate file |
+| `http.tls.keyFile` | path | `null` | TLS private key file |
+| `openFirewall` | bool | `false` | Open firewall for HTTP port |
+
+The git-explorer module uses `DynamicUser=true` and grants read-only access to the repository path.
+
 #### hm-options-mcp / nixos-options-mcp (Legacy)

 | Option | Type | Default | Description |
@@ -579,6 +702,7 @@ go test -bench=. ./internal/database/...
 go build ./cmd/nixpkgs-search
 go build ./cmd/hm-options
 go build ./cmd/lab-monitoring
+go build ./cmd/git-explorer
 ```

 ## License
--- a/cmd/git-explorer/main.go
+++ b/cmd/git-explorer/main.go
@@ -0,0 +1,459 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	"github.com/urfave/cli/v2"
+
+	"code.t-juice.club/torjus/labmcp/internal/gitexplorer"
+	"code.t-juice.club/torjus/labmcp/internal/mcp"
+)
+
+const version = "0.1.0"
+
+func main() {
+	app := &cli.App{
+		Name:    "git-explorer",
+		Usage:   "Read-only MCP server for git repository exploration",
+		Version: version,
+		Flags: []cli.Flag{
+			&cli.StringFlag{
+				Name:    "repo",
+				Aliases: []string{"r"},
+				Usage:   "Path to git repository",
+				EnvVars: []string{"GIT_REPO_PATH"},
+				Value:   ".",
+			},
+			&cli.StringFlag{
+				Name:    "default-remote",
+				Usage:   "Default remote name",
+				EnvVars: []string{"GIT_DEFAULT_REMOTE"},
+				Value:   "origin",
+			},
+		},
+		Commands: []*cli.Command{
+			serveCommand(),
+			resolveCommand(),
+			logCommand(),
+			showCommand(),
+			diffCommand(),
+			catCommand(),
+			branchesCommand(),
+			searchCommand(),
+		},
+	}
+
+	if err := app.Run(os.Args); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func serveCommand() *cli.Command {
+	return &cli.Command{
+		Name:  "serve",
+		Usage: "Run MCP server for git exploration",
+		Flags: []cli.Flag{
+			&cli.StringFlag{
+				Name:    "transport",
+				Aliases: []string{"t"},
+				Usage:   "Transport type: 'stdio' or 'http'",
+				Value:   "stdio",
+			},
+			&cli.StringFlag{
+				Name:  "http-address",
+				Usage: "HTTP listen address",
+				Value: "127.0.0.1:8085",
+			},
+			&cli.StringFlag{
+				Name:  "http-endpoint",
+				Usage: "HTTP endpoint path",
+				Value: "/mcp",
+			},
+			&cli.StringSliceFlag{
+				Name:  "allowed-origins",
+				Usage: "Allowed Origin headers for CORS",
+			},
+			&cli.StringFlag{
+				Name:  "tls-cert",
+				Usage: "TLS certificate file",
+			},
+			&cli.StringFlag{
+				Name:  "tls-key",
+				Usage: "TLS key file",
+			},
+			&cli.DurationFlag{
+				Name:  "session-ttl",
+				Usage: "Session TTL for HTTP transport",
+				Value: 30 * time.Minute,
+			},
+		},
+		Action: func(c *cli.Context) error {
+			return runServe(c)
+		},
+	}
+}
+
+func resolveCommand() *cli.Command {
+	return &cli.Command{
+		Name:      "resolve",
+		Usage:     "Resolve a ref to a commit hash",
+		ArgsUsage: "<ref>",
+		Action: func(c *cli.Context) error {
+			if c.NArg() < 1 {
+				return fmt.Errorf("ref argument required")
+			}
+			return runResolve(c, c.Args().First())
+		},
+	}
+}
+
+func logCommand() *cli.Command {
+	return &cli.Command{
+		Name:  "log",
+		Usage: "Show commit log",
+		Flags: []cli.Flag{
+			&cli.StringFlag{
+				Name:  "ref",
+				Usage: "Starting ref (default: HEAD)",
+				Value: "HEAD",
+			},
+			&cli.IntFlag{
+				Name:    "limit",
+				Aliases: []string{"n"},
+				Usage:   "Maximum number of commits",
+				Value:   10,
+			},
+			&cli.StringFlag{
+				Name:  "author",
+				Usage: "Filter by author",
+			},
+			&cli.StringFlag{
+				Name:  "path",
+				Usage: "Filter by path",
+			},
+		},
+		Action: func(c *cli.Context) error {
+			return runLog(c)
+		},
+	}
+}
+
+func showCommand() *cli.Command {
+	return &cli.Command{
+		Name:      "show",
+		Usage:     "Show commit details",
+		ArgsUsage: "<ref>",
+		Flags: []cli.Flag{
+			&cli.BoolFlag{
+				Name:  "stats",
+				Usage: "Include file statistics",
+				Value: true,
+			},
+		},
+		Action: func(c *cli.Context) error {
+			ref := "HEAD"
+			if c.NArg() > 0 {
+				ref = c.Args().First()
+			}
+			return runShow(c, ref)
+		},
+	}
+}
+
+func diffCommand() *cli.Command {
+	return &cli.Command{
+		Name:      "diff",
+		Usage:     "Show files changed between two commits",
+		ArgsUsage: "<from-ref> <to-ref>",
+		Action: func(c *cli.Context) error {
+			if c.NArg() < 2 {
+				return fmt.Errorf("both from-ref and to-ref arguments required")
+			}
+			return runDiff(c, c.Args().Get(0), c.Args().Get(1))
+		},
+	}
+}
+
+func catCommand() *cli.Command {
+	return &cli.Command{
+		Name:      "cat",
+		Usage:     "Show file contents at a commit",
+		ArgsUsage: "<ref> <path>",
+		Action: func(c *cli.Context) error {
+			if c.NArg() < 2 {
+				return fmt.Errorf("both ref and path arguments required")
+			}
+			return runCat(c, c.Args().Get(0), c.Args().Get(1))
+		},
+	}
+}
+
+func branchesCommand() *cli.Command {
+	return &cli.Command{
+		Name:  "branches",
+		Usage: "List branches",
+		Flags: []cli.Flag{
+			&cli.BoolFlag{
+				Name:    "remote",
+				Aliases: []string{"r"},
+				Usage:   "Include remote branches",
+			},
+		},
+		Action: func(c *cli.Context) error {
+			return runBranches(c)
+		},
+	}
+}
+
+func searchCommand() *cli.Command {
+	return &cli.Command{
+		Name:      "search",
+		Usage:     "Search commit messages",
+		ArgsUsage: "<query>",
+		Flags: []cli.Flag{
+			&cli.StringFlag{
+				Name:  "ref",
+				Usage: "Starting ref (default: HEAD)",
+				Value: "HEAD",
+			},
+			&cli.IntFlag{
+				Name:    "limit",
+				Aliases: []string{"n"},
+				Usage:   "Maximum number of results",
+				Value:   20,
+			},
+		},
+		Action: func(c *cli.Context) error {
+			if c.NArg() < 1 {
+				return fmt.Errorf("query argument required")
+			}
+			return runSearch(c, c.Args().First())
+		},
+	}
+}
+
+func runServe(c *cli.Context) error {
+	ctx, cancel := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
+	defer cancel()
+
+	repoPath := c.String("repo")
+	client, err := gitexplorer.NewGitClient(repoPath, c.String("default-remote"))
+	if err != nil {
+		return fmt.Errorf("failed to open repository: %w", err)
+	}
+
+	logger := log.New(os.Stderr, "[mcp] ", log.LstdFlags)
+	config := mcp.DefaultGitExplorerConfig()
+
+	server := mcp.NewGenericServer(logger, config)
+	gitexplorer.RegisterHandlers(server, client)
+
+	transport := c.String("transport")
+	switch transport {
+	case "stdio":
+		logger.Printf("Starting git-explorer MCP server on stdio (repo: %s)...", repoPath)
+		return server.Run(ctx, os.Stdin, os.Stdout)
+
+	case "http":
+		httpConfig := mcp.HTTPConfig{
+			Address:        c.String("http-address"),
+			Endpoint:       c.String("http-endpoint"),
+			AllowedOrigins: c.StringSlice("allowed-origins"),
+			SessionTTL:     c.Duration("session-ttl"),
+			TLSCertFile:    c.String("tls-cert"),
+			TLSKeyFile:     c.String("tls-key"),
+		}
+		httpTransport := mcp.NewHTTPTransport(server, httpConfig)
+		return httpTransport.Run(ctx)
+
+	default:
+		return fmt.Errorf("unknown transport: %s (use 'stdio' or 'http')", transport)
+	}
+}
+
+func getClient(c *cli.Context) (*gitexplorer.GitClient, error) {
+	return gitexplorer.NewGitClient(c.String("repo"), c.String("default-remote"))
+}
+
+func runResolve(c *cli.Context, ref string) error {
+	client, err := getClient(c)
+	if err != nil {
+		return err
+	}
+
+	result, err := client.ResolveRef(ref)
+	if err != nil {
+		return err
+	}
+
+	fmt.Printf("%s (%s) -> %s\n", result.Ref, result.Type, result.Commit)
+	return nil
+}
+
+func runLog(c *cli.Context) error {
+	client, err := getClient(c)
+	if err != nil {
+		return err
+	}
+
+	entries, err := client.GetLog(
+		c.String("ref"),
+		c.Int("limit"),
+		c.String("author"),
+		"",
+		c.String("path"),
+	)
+	if err != nil {
+		return err
+	}
+
+	if len(entries) == 0 {
+		fmt.Println("No commits found.")
+		return nil
+	}
+
+	for _, e := range entries {
+		fmt.Printf("%s %s\n", e.ShortHash, e.Subject)
+		fmt.Printf("  Author: %s <%s>\n", e.Author, e.Email)
+		fmt.Printf("  Date:   %s\n\n", e.Date.Format("2006-01-02 15:04:05"))
+	}
+
+	return nil
+}
+
+func runShow(c *cli.Context, ref string) error {
+	client, err := getClient(c)
+	if err != nil {
+		return err
+	}
+
+	info, err := client.GetCommitInfo(ref, c.Bool("stats"))
+	if err != nil {
+		return err
+	}
+
+	fmt.Printf("commit %s\n", info.Hash)
+	fmt.Printf("Author: %s <%s>\n", info.Author, info.Email)
+	fmt.Printf("Date:   %s\n", info.Date.Format("2006-01-02 15:04:05"))
+
+	if len(info.Parents) > 0 {
+		fmt.Printf("Parents: %v\n", info.Parents)
+	}
+
+	if info.Stats != nil {
+		fmt.Printf("\n%d file(s) changed, %d insertions(+), %d deletions(-)\n",
+			info.Stats.FilesChanged, info.Stats.Additions, info.Stats.Deletions)
+	}
+
+	fmt.Printf("\n%s", info.Message)
+
+	return nil
+}
+
+func runDiff(c *cli.Context, fromRef, toRef string) error {
+	client, err := getClient(c)
+	if err != nil {
+		return err
+	}
+
+	result, err := client.GetDiffFiles(fromRef, toRef)
+	if err != nil {
+		return err
+	}
+
+	if len(result.Files) == 0 {
+		fmt.Println("No files changed.")
+		return nil
+	}
+
+	fmt.Printf("Comparing %s..%s\n\n", result.FromCommit[:7], result.ToCommit[:7])
+
+	for _, f := range result.Files {
+		status := f.Status[0:1] // First letter: A, M, D, R
+		path := f.Path
+		if f.OldPath != "" {
+			path = fmt.Sprintf("%s -> %s", f.OldPath, f.Path)
+		}
+		fmt.Printf("%s  %s  (+%d -%d)\n", status, path, f.Additions, f.Deletions)
+	}
+
+	return nil
+}
+
+func runCat(c *cli.Context, ref, path string) error {
+	client, err := getClient(c)
+	if err != nil {
+		return err
+	}
+
+	content, err := client.GetFileAtCommit(ref, path)
+	if err != nil {
+		return err
+	}
+
+	fmt.Print(content.Content)
+	return nil
+}
+
+func runBranches(c *cli.Context) error {
+	client, err := getClient(c)
+	if err != nil {
+		return err
+	}
+
+	result, err := client.ListBranches(c.Bool("remote"))
+	if err != nil {
+		return err
+	}
+
+	if result.Total == 0 {
+		fmt.Println("No branches found.")
+		return nil
+	}
+
+	for _, b := range result.Branches {
+		marker := " "
+		if b.IsHead {
+			marker = "*"
+		}
+		remoteMarker := ""
+		if b.IsRemote {
+			remoteMarker = " (remote)"
+		}
+		fmt.Printf("%s %s -> %s%s\n", marker, b.Name, b.Commit[:7], remoteMarker)
+	}
+
+	return nil
+}
+
+func runSearch(c *cli.Context, query string) error {
+	client, err := getClient(c)
+	if err != nil {
+		return err
+	}
+
+	result, err := client.SearchCommits(c.String("ref"), query, c.Int("limit"))
+	if err != nil {
+		return err
+	}
+
+	if result.Count == 0 {
+		fmt.Printf("No commits matching '%s'.\n", query)
+		return nil
+	}
+
+	fmt.Printf("Found %d commit(s) matching '%s':\n\n", result.Count, query)
+	for _, e := range result.Commits {
+		fmt.Printf("%s %s\n", e.ShortHash, e.Subject)
+		fmt.Printf("  Author: %s <%s>\n", e.Author, e.Email)
+		fmt.Printf("  Date:   %s\n\n", e.Date.Format("2006-01-02 15:04:05"))
+	}
+
+	return nil
+}
--- a/cmd/hm-options/main.go
+++ b/cmd/hm-options/main.go
@@ -12,10 +12,10 @@ import (

 	"github.com/urfave/cli/v2"

-	"git.t-juice.club/torjus/labmcp/internal/database"
-	"git.t-juice.club/torjus/labmcp/internal/homemanager"
-	"git.t-juice.club/torjus/labmcp/internal/mcp"
-	"git.t-juice.club/torjus/labmcp/internal/options"
+	"code.t-juice.club/torjus/labmcp/internal/database"
+	"code.t-juice.club/torjus/labmcp/internal/homemanager"
+	"code.t-juice.club/torjus/labmcp/internal/mcp"
+	"code.t-juice.club/torjus/labmcp/internal/options"
 )

 const (
--- a/cmd/lab-monitoring/main.go
+++ b/cmd/lab-monitoring/main.go
@@ -11,11 +11,11 @@ import (

 	"github.com/urfave/cli/v2"

-	"git.t-juice.club/torjus/labmcp/internal/mcp"
-	"git.t-juice.club/torjus/labmcp/internal/monitoring"
+	"code.t-juice.club/torjus/labmcp/internal/mcp"
+	"code.t-juice.club/torjus/labmcp/internal/monitoring"
 )

-const version = "0.3.0"
+const version = "0.3.1"

 func main() {
 	app := &cli.App{
@@ -40,6 +40,16 @@ func main() {
 				Usage:   "Loki base URL (optional, enables log query tools)",
 				EnvVars: []string{"LOKI_URL"},
 			},
+			&cli.StringFlag{
+				Name:    "loki-username",
+				Usage:   "Username for Loki basic auth",
+				EnvVars: []string{"LOKI_USERNAME"},
+			},
+			&cli.StringFlag{
+				Name:    "loki-password",
+				Usage:   "Password for Loki basic auth",
+				EnvVars: []string{"LOKI_PASSWORD"},
+			},
 		},
 		Commands: []*cli.Command{
 			serveCommand(),
@@ -189,7 +199,11 @@ func runServe(c *cli.Context) error {

 	var loki *monitoring.LokiClient
 	if lokiURL := c.String("loki-url"); lokiURL != "" {
-		loki = monitoring.NewLokiClient(lokiURL)
+		loki = monitoring.NewLokiClient(monitoring.LokiClientOptions{
+			BaseURL:  lokiURL,
+			Username: c.String("loki-username"),
+			Password: c.String("loki-password"),
+		})
 	}

 	config.InstructionsFunc = func() string {
@@ -432,7 +446,11 @@ func runLogs(c *cli.Context, logql string) error {
 	}

 	ctx := context.Background()
-	loki := monitoring.NewLokiClient(lokiURL)
+	loki := monitoring.NewLokiClient(monitoring.LokiClientOptions{
+		BaseURL:  lokiURL,
+		Username: c.String("loki-username"),
+		Password: c.String("loki-password"),
+	})

 	now := time.Now()
 	start, err := parseCLITime(c.String("start"), now.Add(-time.Hour))
@@ -487,7 +505,11 @@ func runLabels(c *cli.Context) error {
 	}

 	ctx := context.Background()
-	loki := monitoring.NewLokiClient(lokiURL)
+	loki := monitoring.NewLokiClient(monitoring.LokiClientOptions{
+		BaseURL:  lokiURL,
+		Username: c.String("loki-username"),
+		Password: c.String("loki-password"),
+	})

 	if label := c.String("values"); label != "" {
 		values, err := loki.LabelValues(ctx, label)
--- a/cmd/nixos-options/main.go
+++ b/cmd/nixos-options/main.go
@@ -12,9 +12,9 @@ import (

 	"github.com/urfave/cli/v2"

-	"git.t-juice.club/torjus/labmcp/internal/database"
-	"git.t-juice.club/torjus/labmcp/internal/mcp"
-	"git.t-juice.club/torjus/labmcp/internal/nixos"
+	"code.t-juice.club/torjus/labmcp/internal/database"
+	"code.t-juice.club/torjus/labmcp/internal/mcp"
+	"code.t-juice.club/torjus/labmcp/internal/nixos"
 )

 const (
--- a/cmd/nixpkgs-search/main.go
+++ b/cmd/nixpkgs-search/main.go
@@ -12,15 +12,15 @@ import (

 	"github.com/urfave/cli/v2"

-	"git.t-juice.club/torjus/labmcp/internal/database"
-	"git.t-juice.club/torjus/labmcp/internal/mcp"
-	"git.t-juice.club/torjus/labmcp/internal/nixos"
-	"git.t-juice.club/torjus/labmcp/internal/packages"
+	"code.t-juice.club/torjus/labmcp/internal/database"
+	"code.t-juice.club/torjus/labmcp/internal/mcp"
+	"code.t-juice.club/torjus/labmcp/internal/nixos"
+	"code.t-juice.club/torjus/labmcp/internal/packages"
 )

 const (
 	defaultDatabase = "sqlite://nixpkgs-search.db"
-	version         = "0.3.0"
+	version         = "0.4.0"
 )

 func main() {
@@ -310,7 +310,8 @@ func runOptionsServe(c *cli.Context) error {
 	server := mcp.NewServer(store, logger, config)

 	indexer := nixos.NewIndexer(store)
-	server.RegisterHandlers(indexer)
+	pkgIndexer := packages.NewIndexer(store)
+	server.RegisterHandlersWithPackages(indexer, pkgIndexer)

 	transport := c.String("transport")
 	switch transport {
--- a/flake.lock
+++ b/flake.lock
@@ -2,11 +2,11 @@
  "nodes": {
    "nixpkgs": {
      "locked": {
-        "lastModified": 1770115704,
-        "narHash": "sha256-KHFT9UWOF2yRPlAnSXQJh6uVcgNcWlFqqiAZ7OVlHNc=",
+        "lastModified": 1770841267,
+        "narHash": "sha256-9xejG0KoqsoKEGp2kVbXRlEYtFFcDTHjidiuX8hGO44=",
        "owner": "nixos",
        "repo": "nixpkgs",
-        "rev": "e6eae2ee2110f3d31110d5c222cd395303343b08",
+        "rev": "ec7c70d12ce2fc37cb92aff673dcdca89d187bae",
        "type": "github"
      },
      "original": {
--- a/flake.nix
+++ b/flake.nix
@@ -40,6 +40,13 @@
            mainProgram = "lab-monitoring";
            description = "MCP server for Prometheus and Alertmanager monitoring";
          };
+          git-explorer = pkgs.callPackage ./nix/package.nix {
+            src = ./.;
+            pname = "git-explorer";
+            subPackage = "cmd/git-explorer";
+            mainProgram = "git-explorer";
+            description = "Read-only MCP server for git repository exploration";
+          };
          default = self.packages.${system}.nixpkgs-search;
        });

@@ -50,10 +57,8 @@
        {
          default = pkgs.mkShell {
            buildInputs = with pkgs; [
-              go_1_24
+              go
              gopls
-              gotools
-              go-tools
              golangci-lint
              govulncheck
              postgresql
@@ -84,6 +89,10 @@
          imports = [ ./nix/lab-monitoring-module.nix ];
          services.lab-monitoring.package = lib.mkDefault self.packages.${pkgs.system}.lab-monitoring;
        };
+        git-explorer-mcp = { pkgs, ... }: {
+          imports = [ ./nix/git-explorer-module.nix ];
+          services.git-explorer.package = lib.mkDefault self.packages.${pkgs.system}.git-explorer;
+        };
        default = self.nixosModules.nixpkgs-search-mcp;
      };
    };
--- a/go.mod
+++ b/go.mod
@@ -1,24 +1,43 @@
-module git.t-juice.club/torjus/labmcp
+module code.t-juice.club/torjus/labmcp

 go 1.24

 require (
+	github.com/go-git/go-git/v5 v5.16.4
 	github.com/lib/pq v1.10.9
 	github.com/urfave/cli/v2 v2.27.5
 	modernc.org/sqlite v1.34.4
 )

 require (
+	dario.cat/mergo v1.0.0 // indirect
+	github.com/Microsoft/go-winio v0.6.2 // indirect
+	github.com/ProtonMail/go-crypto v1.1.6 // indirect
+	github.com/cloudflare/circl v1.6.1 // indirect
 	github.com/cpuguy83/go-md2man/v2 v2.0.5 // indirect
+	github.com/cyphar/filepath-securejoin v0.4.1 // indirect
 	github.com/dustin/go-humanize v1.0.1 // indirect
+	github.com/emirpasic/gods v1.18.1 // indirect
+	github.com/go-git/gcfg v1.5.1-0.20230307220236-3a3c6141e376 // indirect
+	github.com/go-git/go-billy/v5 v5.6.2 // indirect
+	github.com/golang/groupcache v0.0.0-20241129210726-2c02b8208cf8 // indirect
 	github.com/google/uuid v1.6.0 // indirect
 	github.com/hashicorp/golang-lru/v2 v2.0.7 // indirect
+	github.com/jbenet/go-context v0.0.0-20150711004518-d14ea06fba99 // indirect
+	github.com/kevinburke/ssh_config v1.2.0 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/ncruces/go-strftime v0.1.9 // indirect
+	github.com/pjbgf/sha1cd v0.3.2 // indirect
 	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
 	github.com/russross/blackfriday/v2 v2.1.0 // indirect
+	github.com/sergi/go-diff v1.3.2-0.20230802210424-5b0b94c5c0d3 // indirect
+	github.com/skeema/knownhosts v1.3.1 // indirect
+	github.com/xanzy/ssh-agent v0.3.3 // indirect
 	github.com/xrash/smetrics v0.0.0-20240521201337-686a1a2994c1 // indirect
-	golang.org/x/sys v0.22.0 // indirect
+	golang.org/x/crypto v0.37.0 // indirect
+	golang.org/x/net v0.39.0 // indirect
+	golang.org/x/sys v0.32.0 // indirect
+	gopkg.in/warnings.v0 v0.1.2 // indirect
 	modernc.org/gc/v3 v3.0.0-20240107210532-573471604cb6 // indirect
 	modernc.org/libc v1.55.3 // indirect
 	modernc.org/mathutil v1.6.0 // indirect
--- a/go.sum
+++ b/go.sum
@@ -1,36 +1,134 @@
+dario.cat/mergo v1.0.0 h1:AGCNq9Evsj31mOgNPcLyXc+4PNABt905YmuqPYYpBWk=
+dario.cat/mergo v1.0.0/go.mod h1:uNxQE+84aUszobStD9th8a29P2fMDhsBdgRYvZOxGmk=
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+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 modernc.org/cc/v4 v4.21.4 h1:3Be/Rdo1fpr8GrQ7IVw9OHtplU4gWbb+wNgeoBMmGLQ=
 modernc.org/cc/v4 v4.21.4/go.mod h1:HM7VJTZbUCR3rV8EYBi9wxnJ0ZBRiGE5OeGXNA0IsLQ=
 modernc.org/ccgo/v4 v4.19.2 h1:lwQZgvboKD0jBwdaeVCTouxhxAyN6iawF3STraAal8Y=
--- a/internal/gitexplorer/client.go
+++ b/internal/gitexplorer/client.go
@@ -0,0 +1,570 @@
+package gitexplorer
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"strings"
+
+	"github.com/go-git/go-git/v5"
+	"github.com/go-git/go-git/v5/plumbing"
+	"github.com/go-git/go-git/v5/plumbing/object"
+)
+
+var (
+	// ErrNotFound is returned when a ref, commit, or file is not found.
+	ErrNotFound = errors.New("not found")
+	// ErrFileTooLarge is returned when a file exceeds the size limit.
+	ErrFileTooLarge = errors.New("file too large")
+)
+
+// GitClient provides read-only access to a git repository.
+type GitClient struct {
+	repo          *git.Repository
+	defaultRemote string
+}
+
+// NewGitClient opens a git repository at the given path.
+func NewGitClient(repoPath string, defaultRemote string) (*GitClient, error) {
+	repo, err := git.PlainOpen(repoPath)
+	if err != nil {
+		return nil, fmt.Errorf("failed to open repository: %w", err)
+	}
+
+	if defaultRemote == "" {
+		defaultRemote = "origin"
+	}
+
+	return &GitClient{
+		repo:          repo,
+		defaultRemote: defaultRemote,
+	}, nil
+}
+
+// ResolveRef resolves a ref (branch, tag, or commit hash) to a commit hash.
+func (c *GitClient) ResolveRef(ref string) (*ResolveResult, error) {
+	result := &ResolveResult{Ref: ref}
+
+	// Try to resolve as a revision
+	hash, err := c.repo.ResolveRevision(plumbing.Revision(ref))
+	if err != nil {
+		return nil, fmt.Errorf("%w: ref '%s'", ErrNotFound, ref)
+	}
+
+	result.Commit = hash.String()
+
+	// Determine the type of ref
+	// Check if it's a branch
+	if _, err := c.repo.Reference(plumbing.NewBranchReferenceName(ref), true); err == nil {
+		result.Type = "branch"
+		return result, nil
+	}
+
+	// Check if it's a remote branch
+	if _, err := c.repo.Reference(plumbing.NewRemoteReferenceName(c.defaultRemote, ref), true); err == nil {
+		result.Type = "branch"
+		return result, nil
+	}
+
+	// Check if it's a tag
+	if _, err := c.repo.Reference(plumbing.NewTagReferenceName(ref), true); err == nil {
+		result.Type = "tag"
+		return result, nil
+	}
+
+	// Default to commit
+	result.Type = "commit"
+	return result, nil
+}
+
+// GetLog returns the commit log starting from the given ref.
+func (c *GitClient) GetLog(ref string, limit int, author string, since string, path string) ([]LogEntry, error) {
+	if limit <= 0 || limit > Limits.MaxLogEntries {
+		limit = Limits.MaxLogEntries
+	}
+
+	// Resolve the ref to a commit hash
+	hash, err := c.repo.ResolveRevision(plumbing.Revision(ref))
+	if err != nil {
+		return nil, fmt.Errorf("%w: ref '%s'", ErrNotFound, ref)
+	}
+
+	logOpts := &git.LogOptions{
+		From: *hash,
+	}
+
+	// Add path filter if specified
+	if path != "" {
+		if err := ValidatePath(path); err != nil {
+			return nil, err
+		}
+		logOpts.PathFilter = func(p string) bool {
+			return strings.HasPrefix(p, path) || p == path
+		}
+	}
+
+	iter, err := c.repo.Log(logOpts)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get log: %w", err)
+	}
+	defer iter.Close()
+
+	var entries []LogEntry
+	err = iter.ForEach(func(commit *object.Commit) error {
+		// Apply author filter
+		if author != "" {
+			authorLower := strings.ToLower(author)
+			if !strings.Contains(strings.ToLower(commit.Author.Name), authorLower) &&
+				!strings.Contains(strings.ToLower(commit.Author.Email), authorLower) {
+				return nil
+			}
+		}
+
+		// Apply since filter
+		if since != "" {
+			// Parse since as a ref and check if this commit is reachable
+			sinceHash, err := c.repo.ResolveRevision(plumbing.Revision(since))
+			if err == nil {
+				// Stop if we've reached the since commit
+				if commit.Hash == *sinceHash {
+					return io.EOF
+				}
+			}
+		}
+
+		// Get first line of commit message as subject
+		subject := commit.Message
+		if idx := strings.Index(subject, "\n"); idx != -1 {
+			subject = subject[:idx]
+		}
+		subject = strings.TrimSpace(subject)
+
+		entries = append(entries, LogEntry{
+			Hash:      commit.Hash.String(),
+			ShortHash: commit.Hash.String()[:7],
+			Author:    commit.Author.Name,
+			Email:     commit.Author.Email,
+			Date:      commit.Author.When,
+			Subject:   subject,
+		})
+
+		if len(entries) >= limit {
+			return io.EOF
+		}
+		return nil
+	})
+
+	// io.EOF is expected when we hit the limit
+	if err != nil && err != io.EOF {
+		return nil, fmt.Errorf("failed to iterate log: %w", err)
+	}
+
+	return entries, nil
+}
+
+// GetCommitInfo returns full details about a commit.
+func (c *GitClient) GetCommitInfo(ref string, includeStats bool) (*CommitInfo, error) {
+	hash, err := c.repo.ResolveRevision(plumbing.Revision(ref))
+	if err != nil {
+		return nil, fmt.Errorf("%w: ref '%s'", ErrNotFound, ref)
+	}
+
+	commit, err := c.repo.CommitObject(*hash)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get commit: %w", err)
+	}
+
+	info := &CommitInfo{
+		Hash:       commit.Hash.String(),
+		Author:     commit.Author.Name,
+		Email:      commit.Author.Email,
+		Date:       commit.Author.When,
+		Committer:  commit.Committer.Name,
+		CommitDate: commit.Committer.When,
+		Message:    commit.Message,
+	}
+
+	for _, parent := range commit.ParentHashes {
+		info.Parents = append(info.Parents, parent.String())
+	}
+
+	if includeStats {
+		stats, err := c.getCommitStats(commit)
+		if err == nil {
+			info.Stats = stats
+		}
+	}
+
+	return info, nil
+}
+
+// getCommitStats computes file change statistics for a commit.
+func (c *GitClient) getCommitStats(commit *object.Commit) (*FileStats, error) {
+	stats, err := commit.Stats()
+	if err != nil {
+		return nil, err
+	}
+
+	result := &FileStats{
+		FilesChanged: len(stats),
+	}
+
+	for _, s := range stats {
+		result.Additions += s.Addition
+		result.Deletions += s.Deletion
+	}
+
+	return result, nil
+}
+
+// GetDiffFiles returns the files changed between two commits.
+func (c *GitClient) GetDiffFiles(fromRef, toRef string) (*DiffResult, error) {
+	fromHash, err := c.repo.ResolveRevision(plumbing.Revision(fromRef))
+	if err != nil {
+		return nil, fmt.Errorf("%w: ref '%s'", ErrNotFound, fromRef)
+	}
+
+	toHash, err := c.repo.ResolveRevision(plumbing.Revision(toRef))
+	if err != nil {
+		return nil, fmt.Errorf("%w: ref '%s'", ErrNotFound, toRef)
+	}
+
+	fromCommit, err := c.repo.CommitObject(*fromHash)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get from commit: %w", err)
+	}
+
+	toCommit, err := c.repo.CommitObject(*toHash)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get to commit: %w", err)
+	}
+
+	patch, err := fromCommit.Patch(toCommit)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get patch: %w", err)
+	}
+
+	result := &DiffResult{
+		FromCommit: fromHash.String(),
+		ToCommit:   toHash.String(),
+	}
+
+	for i, filePatch := range patch.FilePatches() {
+		if i >= Limits.MaxDiffFiles {
+			break
+		}
+
+		from, to := filePatch.Files()
+
+		df := DiffFile{}
+
+		// Determine status and paths
+		switch {
+		case from == nil && to != nil:
+			df.Status = "added"
+			df.Path = to.Path()
+		case from != nil && to == nil:
+			df.Status = "deleted"
+			df.Path = from.Path()
+		case from != nil && to != nil && from.Path() != to.Path():
+			df.Status = "renamed"
+			df.Path = to.Path()
+			df.OldPath = from.Path()
+		default:
+			df.Status = "modified"
+			if to != nil {
+				df.Path = to.Path()
+			} else if from != nil {
+				df.Path = from.Path()
+			}
+		}
+
+		// Count additions and deletions
+		for _, chunk := range filePatch.Chunks() {
+			content := chunk.Content()
+			lines := strings.Split(content, "\n")
+			switch chunk.Type() {
+			case 1: // Add
+				df.Additions += len(lines)
+			case 2: // Delete
+				df.Deletions += len(lines)
+			}
+		}
+
+		result.Files = append(result.Files, df)
+	}
+
+	return result, nil
+}
+
+// GetFileAtCommit returns the content of a file at a specific commit.
+func (c *GitClient) GetFileAtCommit(ref, path string) (*FileContent, error) {
+	if err := ValidatePath(path); err != nil {
+		return nil, err
+	}
+
+	hash, err := c.repo.ResolveRevision(plumbing.Revision(ref))
+	if err != nil {
+		return nil, fmt.Errorf("%w: ref '%s'", ErrNotFound, ref)
+	}
+
+	commit, err := c.repo.CommitObject(*hash)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get commit: %w", err)
+	}
+
+	file, err := commit.File(path)
+	if err != nil {
+		return nil, fmt.Errorf("%w: file '%s'", ErrNotFound, path)
+	}
+
+	// Check file size
+	if file.Size > Limits.MaxFileContent {
+		return nil, fmt.Errorf("%w: %d bytes (max %d)", ErrFileTooLarge, file.Size, Limits.MaxFileContent)
+	}
+
+	content, err := file.Contents()
+	if err != nil {
+		return nil, fmt.Errorf("failed to read file: %w", err)
+	}
+
+	return &FileContent{
+		Path:    path,
+		Commit:  hash.String(),
+		Size:    file.Size,
+		Content: content,
+	}, nil
+}
+
+// IsAncestor checks if ancestor is an ancestor of descendant.
+func (c *GitClient) IsAncestor(ancestorRef, descendantRef string) (*AncestryResult, error) {
+	ancestorHash, err := c.repo.ResolveRevision(plumbing.Revision(ancestorRef))
+	if err != nil {
+		return nil, fmt.Errorf("%w: ref '%s'", ErrNotFound, ancestorRef)
+	}
+
+	descendantHash, err := c.repo.ResolveRevision(plumbing.Revision(descendantRef))
+	if err != nil {
+		return nil, fmt.Errorf("%w: ref '%s'", ErrNotFound, descendantRef)
+	}
+
+	ancestorCommit, err := c.repo.CommitObject(*ancestorHash)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get ancestor commit: %w", err)
+	}
+
+	descendantCommit, err := c.repo.CommitObject(*descendantHash)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get descendant commit: %w", err)
+	}
+
+	isAncestor, err := ancestorCommit.IsAncestor(descendantCommit)
+	if err != nil {
+		return nil, fmt.Errorf("failed to check ancestry: %w", err)
+	}
+
+	return &AncestryResult{
+		Ancestor:   ancestorHash.String(),
+		Descendant: descendantHash.String(),
+		IsAncestor: isAncestor,
+	}, nil
+}
+
+// CommitsBetween returns commits between two refs (exclusive of from, inclusive of to).
+func (c *GitClient) CommitsBetween(fromRef, toRef string, limit int) (*CommitRange, error) {
+	if limit <= 0 || limit > Limits.MaxLogEntries {
+		limit = Limits.MaxLogEntries
+	}
+
+	fromHash, err := c.repo.ResolveRevision(plumbing.Revision(fromRef))
+	if err != nil {
+		return nil, fmt.Errorf("%w: ref '%s'", ErrNotFound, fromRef)
+	}
+
+	toHash, err := c.repo.ResolveRevision(plumbing.Revision(toRef))
+	if err != nil {
+		return nil, fmt.Errorf("%w: ref '%s'", ErrNotFound, toRef)
+	}
+
+	iter, err := c.repo.Log(&git.LogOptions{
+		From: *toHash,
+	})
+	if err != nil {
+		return nil, fmt.Errorf("failed to get log: %w", err)
+	}
+	defer iter.Close()
+
+	result := &CommitRange{
+		FromCommit: fromHash.String(),
+		ToCommit:   toHash.String(),
+	}
+
+	err = iter.ForEach(func(commit *object.Commit) error {
+		// Stop when we reach the from commit (exclusive)
+		if commit.Hash == *fromHash {
+			return io.EOF
+		}
+
+		subject := commit.Message
+		if idx := strings.Index(subject, "\n"); idx != -1 {
+			subject = subject[:idx]
+		}
+		subject = strings.TrimSpace(subject)
+
+		result.Commits = append(result.Commits, LogEntry{
+			Hash:      commit.Hash.String(),
+			ShortHash: commit.Hash.String()[:7],
+			Author:    commit.Author.Name,
+			Email:     commit.Author.Email,
+			Date:      commit.Author.When,
+			Subject:   subject,
+		})
+
+		if len(result.Commits) >= limit {
+			return io.EOF
+		}
+		return nil
+	})
+
+	if err != nil && err != io.EOF {
+		return nil, fmt.Errorf("failed to iterate log: %w", err)
+	}
+
+	result.Count = len(result.Commits)
+	return result, nil
+}
+
+// ListBranches returns all branches in the repository.
+func (c *GitClient) ListBranches(includeRemote bool) (*BranchList, error) {
+	result := &BranchList{}
+
+	// Get HEAD to determine current branch
+	head, err := c.repo.Head()
+	if err == nil && head.Name().IsBranch() {
+		result.Current = head.Name().Short()
+	}
+
+	// List local branches
+	branchIter, err := c.repo.Branches()
+	if err != nil {
+		return nil, fmt.Errorf("failed to list branches: %w", err)
+	}
+
+	err = branchIter.ForEach(func(ref *plumbing.Reference) error {
+		if len(result.Branches) >= Limits.MaxBranches {
+			return io.EOF
+		}
+
+		branch := Branch{
+			Name:     ref.Name().Short(),
+			Commit:   ref.Hash().String(),
+			IsRemote: false,
+			IsHead:   ref.Name().Short() == result.Current,
+		}
+
+		result.Branches = append(result.Branches, branch)
+		return nil
+	})
+	if err != nil && err != io.EOF {
+		return nil, fmt.Errorf("failed to iterate branches: %w", err)
+	}
+
+	// List remote branches if requested
+	if includeRemote {
+		refs, err := c.repo.References()
+		if err != nil {
+			return nil, fmt.Errorf("failed to list references: %w", err)
+		}
+
+		err = refs.ForEach(func(ref *plumbing.Reference) error {
+			if len(result.Branches) >= Limits.MaxBranches {
+				return io.EOF
+			}
+
+			if ref.Name().IsRemote() {
+				branch := Branch{
+					Name:     ref.Name().Short(),
+					Commit:   ref.Hash().String(),
+					IsRemote: true,
+					IsHead:   false,
+				}
+				result.Branches = append(result.Branches, branch)
+			}
+			return nil
+		})
+		if err != nil && err != io.EOF {
+			return nil, fmt.Errorf("failed to iterate references: %w", err)
+		}
+	}
+
+	result.Total = len(result.Branches)
+	return result, nil
+}
+
+// SearchCommits searches commit messages for a pattern.
+func (c *GitClient) SearchCommits(ref, query string, limit int) (*SearchResult, error) {
+	if limit <= 0 || limit > Limits.MaxSearchResult {
+		limit = Limits.MaxSearchResult
+	}
+
+	hash, err := c.repo.ResolveRevision(plumbing.Revision(ref))
+	if err != nil {
+		return nil, fmt.Errorf("%w: ref '%s'", ErrNotFound, ref)
+	}
+
+	iter, err := c.repo.Log(&git.LogOptions{
+		From: *hash,
+	})
+	if err != nil {
+		return nil, fmt.Errorf("failed to get log: %w", err)
+	}
+	defer iter.Close()
+
+	result := &SearchResult{
+		Query: query,
+	}
+	queryLower := strings.ToLower(query)
+
+	// We need to scan more commits to find matches
+	scanned := 0
+	maxScan := limit * 100 // Scan up to 100x the limit
+
+	err = iter.ForEach(func(commit *object.Commit) error {
+		scanned++
+		if scanned > maxScan {
+			return io.EOF
+		}
+
+		// Search in message (case-insensitive)
+		if !strings.Contains(strings.ToLower(commit.Message), queryLower) {
+			return nil
+		}
+
+		subject := commit.Message
+		if idx := strings.Index(subject, "\n"); idx != -1 {
+			subject = subject[:idx]
+		}
+		subject = strings.TrimSpace(subject)
+
+		result.Commits = append(result.Commits, LogEntry{
+			Hash:      commit.Hash.String(),
+			ShortHash: commit.Hash.String()[:7],
+			Author:    commit.Author.Name,
+			Email:     commit.Author.Email,
+			Date:      commit.Author.When,
+			Subject:   subject,
+		})
+
+		if len(result.Commits) >= limit {
+			return io.EOF
+		}
+		return nil
+	})
+
+	if err != nil && err != io.EOF {
+		return nil, fmt.Errorf("failed to search commits: %w", err)
+	}
+
+	result.Count = len(result.Commits)
+	return result, nil
+}
--- a/internal/gitexplorer/client_test.go
+++ b/internal/gitexplorer/client_test.go
@@ -0,0 +1,446 @@
+package gitexplorer
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/go-git/go-git/v5"
+	"github.com/go-git/go-git/v5/plumbing/object"
+)
+
+// createTestRepo creates a temporary git repository with some commits for testing.
+func createTestRepo(t *testing.T) (string, func()) {
+	t.Helper()
+
+	dir, err := os.MkdirTemp("", "gitexplorer-test-*")
+	if err != nil {
+		t.Fatalf("failed to create temp dir: %v", err)
+	}
+
+	cleanup := func() {
+		_ = os.RemoveAll(dir)
+	}
+
+	repo, err := git.PlainInit(dir, false)
+	if err != nil {
+		cleanup()
+		t.Fatalf("failed to init repo: %v", err)
+	}
+
+	wt, err := repo.Worktree()
+	if err != nil {
+		cleanup()
+		t.Fatalf("failed to get worktree: %v", err)
+	}
+
+	// Create initial file and commit
+	readme := filepath.Join(dir, "README.md")
+	if err := os.WriteFile(readme, []byte("# Test Repo\n"), 0644); err != nil {
+		cleanup()
+		t.Fatalf("failed to write README: %v", err)
+	}
+
+	if _, err := wt.Add("README.md"); err != nil {
+		cleanup()
+		t.Fatalf("failed to add README: %v", err)
+	}
+
+	sig := &object.Signature{
+		Name:  "Test User",
+		Email: "test@example.com",
+		When:  time.Now().Add(-2 * time.Hour),
+	}
+
+	_, err = wt.Commit("Initial commit", &git.CommitOptions{Author: sig})
+	if err != nil {
+		cleanup()
+		t.Fatalf("failed to create initial commit: %v", err)
+	}
+
+	// Create a second file and commit
+	subdir := filepath.Join(dir, "src")
+	if err := os.MkdirAll(subdir, 0755); err != nil {
+		cleanup()
+		t.Fatalf("failed to create subdir: %v", err)
+	}
+
+	mainFile := filepath.Join(subdir, "main.go")
+	if err := os.WriteFile(mainFile, []byte("package main\n\nfunc main() {}\n"), 0644); err != nil {
+		cleanup()
+		t.Fatalf("failed to write main.go: %v", err)
+	}
+
+	if _, err := wt.Add("src/main.go"); err != nil {
+		cleanup()
+		t.Fatalf("failed to add main.go: %v", err)
+	}
+
+	sig.When = time.Now().Add(-1 * time.Hour)
+	_, err = wt.Commit("Add main.go", &git.CommitOptions{Author: sig})
+	if err != nil {
+		cleanup()
+		t.Fatalf("failed to create second commit: %v", err)
+	}
+
+	// Update README and commit
+	if err := os.WriteFile(readme, []byte("# Test Repo\n\nThis is a test repository.\n"), 0644); err != nil {
+		cleanup()
+		t.Fatalf("failed to update README: %v", err)
+	}
+
+	if _, err := wt.Add("README.md"); err != nil {
+		cleanup()
+		t.Fatalf("failed to add updated README: %v", err)
+	}
+
+	sig.When = time.Now()
+	_, err = wt.Commit("Update README", &git.CommitOptions{Author: sig})
+	if err != nil {
+		cleanup()
+		t.Fatalf("failed to create third commit: %v", err)
+	}
+
+	return dir, cleanup
+}
+
+func TestNewGitClient(t *testing.T) {
+	repoPath, cleanup := createTestRepo(t)
+	defer cleanup()
+
+	client, err := NewGitClient(repoPath, "")
+	if err != nil {
+		t.Fatalf("NewGitClient failed: %v", err)
+	}
+	if client == nil {
+		t.Fatal("client is nil")
+	}
+	if client.defaultRemote != "origin" {
+		t.Errorf("defaultRemote = %q, want %q", client.defaultRemote, "origin")
+	}
+
+	// Test with invalid path
+	_, err = NewGitClient("/nonexistent/path", "")
+	if err == nil {
+		t.Error("expected error for nonexistent path")
+	}
+}
+
+func TestResolveRef(t *testing.T) {
+	repoPath, cleanup := createTestRepo(t)
+	defer cleanup()
+
+	client, err := NewGitClient(repoPath, "")
+	if err != nil {
+		t.Fatalf("NewGitClient failed: %v", err)
+	}
+
+	// Test resolving HEAD
+	result, err := client.ResolveRef("HEAD")
+	if err != nil {
+		t.Fatalf("ResolveRef(HEAD) failed: %v", err)
+	}
+	if result.Commit == "" {
+		t.Error("commit hash is empty")
+	}
+
+	// Test resolving master branch
+	result, err = client.ResolveRef("master")
+	if err != nil {
+		t.Fatalf("ResolveRef(master) failed: %v", err)
+	}
+	if result.Type != "branch" {
+		t.Errorf("type = %q, want %q", result.Type, "branch")
+	}
+
+	// Test resolving invalid ref
+	_, err = client.ResolveRef("nonexistent")
+	if err == nil {
+		t.Error("expected error for nonexistent ref")
+	}
+}
+
+func TestGetLog(t *testing.T) {
+	repoPath, cleanup := createTestRepo(t)
+	defer cleanup()
+
+	client, err := NewGitClient(repoPath, "")
+	if err != nil {
+		t.Fatalf("NewGitClient failed: %v", err)
+	}
+
+	// Get full log
+	entries, err := client.GetLog("HEAD", 10, "", "", "")
+	if err != nil {
+		t.Fatalf("GetLog failed: %v", err)
+	}
+	if len(entries) != 3 {
+		t.Errorf("got %d entries, want 3", len(entries))
+	}
+
+	// Check order (newest first)
+	if entries[0].Subject != "Update README" {
+		t.Errorf("first entry subject = %q, want %q", entries[0].Subject, "Update README")
+	}
+
+	// Test with limit
+	entries, err = client.GetLog("HEAD", 1, "", "", "")
+	if err != nil {
+		t.Fatalf("GetLog with limit failed: %v", err)
+	}
+	if len(entries) != 1 {
+		t.Errorf("got %d entries, want 1", len(entries))
+	}
+
+	// Test with author filter
+	entries, err = client.GetLog("HEAD", 10, "Test User", "", "")
+	if err != nil {
+		t.Fatalf("GetLog with author failed: %v", err)
+	}
+	if len(entries) != 3 {
+		t.Errorf("got %d entries, want 3", len(entries))
+	}
+
+	entries, err = client.GetLog("HEAD", 10, "nonexistent", "", "")
+	if err != nil {
+		t.Fatalf("GetLog with nonexistent author failed: %v", err)
+	}
+	if len(entries) != 0 {
+		t.Errorf("got %d entries, want 0", len(entries))
+	}
+
+	// Test with path filter
+	entries, err = client.GetLog("HEAD", 10, "", "", "src")
+	if err != nil {
+		t.Fatalf("GetLog with path failed: %v", err)
+	}
+	if len(entries) != 1 {
+		t.Errorf("got %d entries, want 1 (only src/main.go commit)", len(entries))
+	}
+}
+
+func TestGetCommitInfo(t *testing.T) {
+	repoPath, cleanup := createTestRepo(t)
+	defer cleanup()
+
+	client, err := NewGitClient(repoPath, "")
+	if err != nil {
+		t.Fatalf("NewGitClient failed: %v", err)
+	}
+
+	info, err := client.GetCommitInfo("HEAD", true)
+	if err != nil {
+		t.Fatalf("GetCommitInfo failed: %v", err)
+	}
+
+	if info.Author != "Test User" {
+		t.Errorf("author = %q, want %q", info.Author, "Test User")
+	}
+	if info.Email != "test@example.com" {
+		t.Errorf("email = %q, want %q", info.Email, "test@example.com")
+	}
+	if len(info.Parents) != 1 {
+		t.Errorf("parents = %d, want 1", len(info.Parents))
+	}
+	if info.Stats == nil {
+		t.Error("stats is nil")
+	}
+
+	// Test without stats
+	info, err = client.GetCommitInfo("HEAD", false)
+	if err != nil {
+		t.Fatalf("GetCommitInfo without stats failed: %v", err)
+	}
+	if info.Stats != nil {
+		t.Error("stats should be nil")
+	}
+}
+
+func TestGetDiffFiles(t *testing.T) {
+	repoPath, cleanup := createTestRepo(t)
+	defer cleanup()
+
+	client, err := NewGitClient(repoPath, "")
+	if err != nil {
+		t.Fatalf("NewGitClient failed: %v", err)
+	}
+
+	result, err := client.GetDiffFiles("HEAD~2", "HEAD")
+	if err != nil {
+		t.Fatalf("GetDiffFiles failed: %v", err)
+	}
+
+	if len(result.Files) < 1 {
+		t.Error("expected at least one changed file")
+	}
+
+	// Check that we have the expected files
+	foundReadme := false
+	foundMain := false
+	for _, f := range result.Files {
+		if f.Path == "README.md" {
+			foundReadme = true
+		}
+		if f.Path == "src/main.go" {
+			foundMain = true
+		}
+	}
+	if !foundReadme {
+		t.Error("expected README.md in diff")
+	}
+	if !foundMain {
+		t.Error("expected src/main.go in diff")
+	}
+}
+
+func TestGetFileAtCommit(t *testing.T) {
+	repoPath, cleanup := createTestRepo(t)
+	defer cleanup()
+
+	client, err := NewGitClient(repoPath, "")
+	if err != nil {
+		t.Fatalf("NewGitClient failed: %v", err)
+	}
+
+	content, err := client.GetFileAtCommit("HEAD", "README.md")
+	if err != nil {
+		t.Fatalf("GetFileAtCommit failed: %v", err)
+	}
+
+	if content.Path != "README.md" {
+		t.Errorf("path = %q, want %q", content.Path, "README.md")
+	}
+	if content.Content == "" {
+		t.Error("content is empty")
+	}
+
+	// Test nested file
+	content, err = client.GetFileAtCommit("HEAD", "src/main.go")
+	if err != nil {
+		t.Fatalf("GetFileAtCommit for nested file failed: %v", err)
+	}
+	if content.Path != "src/main.go" {
+		t.Errorf("path = %q, want %q", content.Path, "src/main.go")
+	}
+
+	// Test nonexistent file
+	_, err = client.GetFileAtCommit("HEAD", "nonexistent.txt")
+	if err == nil {
+		t.Error("expected error for nonexistent file")
+	}
+
+	// Test path traversal
+	_, err = client.GetFileAtCommit("HEAD", "../../../etc/passwd")
+	if err == nil {
+		t.Error("expected error for path traversal")
+	}
+}
+
+func TestIsAncestor(t *testing.T) {
+	repoPath, cleanup := createTestRepo(t)
+	defer cleanup()
+
+	client, err := NewGitClient(repoPath, "")
+	if err != nil {
+		t.Fatalf("NewGitClient failed: %v", err)
+	}
+
+	// First commit is ancestor of HEAD
+	result, err := client.IsAncestor("HEAD~2", "HEAD")
+	if err != nil {
+		t.Fatalf("IsAncestor failed: %v", err)
+	}
+	if !result.IsAncestor {
+		t.Error("HEAD~2 should be ancestor of HEAD")
+	}
+
+	// HEAD is not ancestor of first commit
+	result, err = client.IsAncestor("HEAD", "HEAD~2")
+	if err != nil {
+		t.Fatalf("IsAncestor failed: %v", err)
+	}
+	if result.IsAncestor {
+		t.Error("HEAD should not be ancestor of HEAD~2")
+	}
+}
+
+func TestCommitsBetween(t *testing.T) {
+	repoPath, cleanup := createTestRepo(t)
+	defer cleanup()
+
+	client, err := NewGitClient(repoPath, "")
+	if err != nil {
+		t.Fatalf("NewGitClient failed: %v", err)
+	}
+
+	result, err := client.CommitsBetween("HEAD~2", "HEAD", 10)
+	if err != nil {
+		t.Fatalf("CommitsBetween failed: %v", err)
+	}
+
+	// Should have 2 commits (HEAD~1 and HEAD, exclusive of HEAD~2)
+	if result.Count != 2 {
+		t.Errorf("count = %d, want 2", result.Count)
+	}
+}
+
+func TestListBranches(t *testing.T) {
+	repoPath, cleanup := createTestRepo(t)
+	defer cleanup()
+
+	client, err := NewGitClient(repoPath, "")
+	if err != nil {
+		t.Fatalf("NewGitClient failed: %v", err)
+	}
+
+	result, err := client.ListBranches(false)
+	if err != nil {
+		t.Fatalf("ListBranches failed: %v", err)
+	}
+
+	if result.Total < 1 {
+		t.Error("expected at least one branch")
+	}
+
+	foundMaster := false
+	for _, b := range result.Branches {
+		if b.Name == "master" {
+			foundMaster = true
+			if !b.IsHead {
+				t.Error("master should be HEAD")
+			}
+		}
+	}
+	if !foundMaster {
+		t.Error("expected master branch")
+	}
+}
+
+func TestSearchCommits(t *testing.T) {
+	repoPath, cleanup := createTestRepo(t)
+	defer cleanup()
+
+	client, err := NewGitClient(repoPath, "")
+	if err != nil {
+		t.Fatalf("NewGitClient failed: %v", err)
+	}
+
+	result, err := client.SearchCommits("HEAD", "README", 10)
+	if err != nil {
+		t.Fatalf("SearchCommits failed: %v", err)
+	}
+
+	if result.Count < 1 {
+		t.Error("expected at least one match for 'README'")
+	}
+
+	// Search with no matches
+	result, err = client.SearchCommits("HEAD", "nonexistent-query-xyz", 10)
+	if err != nil {
+		t.Fatalf("SearchCommits for no match failed: %v", err)
+	}
+	if result.Count != 0 {
+		t.Errorf("count = %d, want 0", result.Count)
+	}
+}
--- a/internal/gitexplorer/format.go
+++ b/internal/gitexplorer/format.go
@@ -0,0 +1,195 @@
+package gitexplorer
+
+import (
+	"fmt"
+	"strings"
+)
+
+// FormatResolveResult formats a ResolveResult as markdown.
+func FormatResolveResult(r *ResolveResult) string {
+	var sb strings.Builder
+	sb.WriteString(fmt.Sprintf("**Ref:** %s\n", r.Ref))
+	sb.WriteString(fmt.Sprintf("**Type:** %s\n", r.Type))
+	sb.WriteString(fmt.Sprintf("**Commit:** %s\n", r.Commit))
+	return sb.String()
+}
+
+// FormatLogEntries formats a slice of LogEntry as markdown.
+func FormatLogEntries(entries []LogEntry) string {
+	if len(entries) == 0 {
+		return "No commits found."
+	}
+
+	var sb strings.Builder
+	sb.WriteString(fmt.Sprintf("## Commit Log (%d commits)\n\n", len(entries)))
+
+	for _, e := range entries {
+		sb.WriteString(fmt.Sprintf("### %s %s\n", e.ShortHash, e.Subject))
+		sb.WriteString(fmt.Sprintf("**Author:** %s <%s>\n", e.Author, e.Email))
+		sb.WriteString(fmt.Sprintf("**Date:** %s\n\n", e.Date.Format("2006-01-02 15:04:05")))
+	}
+
+	return sb.String()
+}
+
+// FormatCommitInfo formats a CommitInfo as markdown.
+func FormatCommitInfo(info *CommitInfo) string {
+	var sb strings.Builder
+	sb.WriteString("## Commit Details\n\n")
+	sb.WriteString(fmt.Sprintf("**Hash:** %s\n", info.Hash))
+	sb.WriteString(fmt.Sprintf("**Author:** %s <%s>\n", info.Author, info.Email))
+	sb.WriteString(fmt.Sprintf("**Date:** %s\n", info.Date.Format("2006-01-02 15:04:05")))
+	sb.WriteString(fmt.Sprintf("**Committer:** %s\n", info.Committer))
+	sb.WriteString(fmt.Sprintf("**Commit Date:** %s\n", info.CommitDate.Format("2006-01-02 15:04:05")))
+
+	if len(info.Parents) > 0 {
+		sb.WriteString(fmt.Sprintf("**Parents:** %s\n", strings.Join(info.Parents, ", ")))
+	}
+
+	if info.Stats != nil {
+		sb.WriteString(fmt.Sprintf("**Changes:** %d file(s), +%d -%d\n",
+			info.Stats.FilesChanged, info.Stats.Additions, info.Stats.Deletions))
+	}
+
+	sb.WriteString("\n### Message\n\n")
+	sb.WriteString("```\n")
+	sb.WriteString(info.Message)
+	if !strings.HasSuffix(info.Message, "\n") {
+		sb.WriteString("\n")
+	}
+	sb.WriteString("```\n")
+
+	return sb.String()
+}
+
+// FormatDiffResult formats a DiffResult as markdown.
+func FormatDiffResult(r *DiffResult) string {
+	if len(r.Files) == 0 {
+		return "No files changed."
+	}
+
+	var sb strings.Builder
+	sb.WriteString(fmt.Sprintf("## Files Changed (%d files)\n\n", len(r.Files)))
+	sb.WriteString(fmt.Sprintf("**From:** %s\n", r.FromCommit[:7]))
+	sb.WriteString(fmt.Sprintf("**To:** %s\n\n", r.ToCommit[:7]))
+
+	sb.WriteString("| Status | Path | Changes |\n")
+	sb.WriteString("|--------|------|--------|\n")
+
+	for _, f := range r.Files {
+		path := f.Path
+		if f.OldPath != "" {
+			path = fmt.Sprintf("%s → %s", f.OldPath, f.Path)
+		}
+		changes := fmt.Sprintf("+%d -%d", f.Additions, f.Deletions)
+		sb.WriteString(fmt.Sprintf("| %s | %s | %s |\n", f.Status, path, changes))
+	}
+
+	return sb.String()
+}
+
+// FormatFileContent formats a FileContent as markdown.
+func FormatFileContent(c *FileContent) string {
+	var sb strings.Builder
+	sb.WriteString(fmt.Sprintf("## File: %s\n\n", c.Path))
+	sb.WriteString(fmt.Sprintf("**Commit:** %s\n", c.Commit[:7]))
+	sb.WriteString(fmt.Sprintf("**Size:** %d bytes\n\n", c.Size))
+
+	// Determine language hint from extension
+	ext := ""
+	if idx := strings.LastIndex(c.Path, "."); idx != -1 {
+		ext = c.Path[idx+1:]
+	}
+
+	sb.WriteString(fmt.Sprintf("```%s\n", ext))
+	sb.WriteString(c.Content)
+	if !strings.HasSuffix(c.Content, "\n") {
+		sb.WriteString("\n")
+	}
+	sb.WriteString("```\n")
+
+	return sb.String()
+}
+
+// FormatAncestryResult formats an AncestryResult as markdown.
+func FormatAncestryResult(r *AncestryResult) string {
+	var sb strings.Builder
+	sb.WriteString("## Ancestry Check\n\n")
+	sb.WriteString(fmt.Sprintf("**Ancestor:** %s\n", r.Ancestor[:7]))
+	sb.WriteString(fmt.Sprintf("**Descendant:** %s\n", r.Descendant[:7]))
+
+	if r.IsAncestor {
+		sb.WriteString("\n✓ **Yes**, the first commit is an ancestor of the second.\n")
+	} else {
+		sb.WriteString("\n✗ **No**, the first commit is not an ancestor of the second.\n")
+	}
+
+	return sb.String()
+}
+
+// FormatCommitRange formats a CommitRange as markdown.
+func FormatCommitRange(r *CommitRange) string {
+	if r.Count == 0 {
+		return "No commits in range."
+	}
+
+	var sb strings.Builder
+	sb.WriteString(fmt.Sprintf("## Commits Between (%d commits)\n\n", r.Count))
+	sb.WriteString(fmt.Sprintf("**From:** %s (exclusive)\n", r.FromCommit[:7]))
+	sb.WriteString(fmt.Sprintf("**To:** %s (inclusive)\n\n", r.ToCommit[:7]))
+
+	for _, e := range r.Commits {
+		sb.WriteString(fmt.Sprintf("- **%s** %s (%s)\n", e.ShortHash, e.Subject, e.Author))
+	}
+
+	return sb.String()
+}
+
+// FormatBranchList formats a BranchList as markdown.
+func FormatBranchList(r *BranchList) string {
+	if r.Total == 0 {
+		return "No branches found."
+	}
+
+	var sb strings.Builder
+	sb.WriteString(fmt.Sprintf("## Branches (%d total)\n\n", r.Total))
+
+	if r.Current != "" {
+		sb.WriteString(fmt.Sprintf("**Current branch:** %s\n\n", r.Current))
+	}
+
+	sb.WriteString("| Branch | Commit | Type |\n")
+	sb.WriteString("|--------|--------|------|\n")
+
+	for _, b := range r.Branches {
+		branchType := "local"
+		if b.IsRemote {
+			branchType = "remote"
+		}
+		marker := ""
+		if b.IsHead {
+			marker = " ✓"
+		}
+		sb.WriteString(fmt.Sprintf("| %s%s | %s | %s |\n", b.Name, marker, b.Commit[:7], branchType))
+	}
+
+	return sb.String()
+}
+
+// FormatSearchResult formats a SearchResult as markdown.
+func FormatSearchResult(r *SearchResult) string {
+	if r.Count == 0 {
+		return fmt.Sprintf("No commits found matching '%s'.", r.Query)
+	}
+
+	var sb strings.Builder
+	sb.WriteString(fmt.Sprintf("## Search Results for '%s' (%d matches)\n\n", r.Query, r.Count))
+
+	for _, e := range r.Commits {
+		sb.WriteString(fmt.Sprintf("### %s %s\n", e.ShortHash, e.Subject))
+		sb.WriteString(fmt.Sprintf("**Author:** %s <%s>\n", e.Author, e.Email))
+		sb.WriteString(fmt.Sprintf("**Date:** %s\n\n", e.Date.Format("2006-01-02 15:04:05")))
+	}
+
+	return sb.String()
+}
--- a/internal/gitexplorer/handlers.go
+++ b/internal/gitexplorer/handlers.go
@@ -0,0 +1,440 @@
+package gitexplorer
+
+import (
+	"context"
+	"fmt"
+
+	"code.t-juice.club/torjus/labmcp/internal/mcp"
+)
+
+// RegisterHandlers registers all git-explorer tool handlers on the MCP server.
+func RegisterHandlers(server *mcp.Server, client *GitClient) {
+	server.RegisterTool(resolveRefTool(), makeResolveRefHandler(client))
+	server.RegisterTool(getLogTool(), makeGetLogHandler(client))
+	server.RegisterTool(getCommitInfoTool(), makeGetCommitInfoHandler(client))
+	server.RegisterTool(getDiffFilesTool(), makeGetDiffFilesHandler(client))
+	server.RegisterTool(getFileAtCommitTool(), makeGetFileAtCommitHandler(client))
+	server.RegisterTool(isAncestorTool(), makeIsAncestorHandler(client))
+	server.RegisterTool(commitsBetweenTool(), makeCommitsBetweenHandler(client))
+	server.RegisterTool(listBranchesTool(), makeListBranchesHandler(client))
+	server.RegisterTool(searchCommitsTool(), makeSearchCommitsHandler(client))
+}
+
+// Tool definitions
+
+func resolveRefTool() mcp.Tool {
+	return mcp.Tool{
+		Name:        "resolve_ref",
+		Description: "Resolve a git ref (branch, tag, or commit hash) to its full commit hash",
+		InputSchema: mcp.InputSchema{
+			Type: "object",
+			Properties: map[string]mcp.Property{
+				"ref": {
+					Type:        "string",
+					Description: "Git ref to resolve (e.g., 'main', 'v1.0.0', 'HEAD', commit hash)",
+				},
+			},
+			Required: []string{"ref"},
+		},
+	}
+}
+
+func getLogTool() mcp.Tool {
+	return mcp.Tool{
+		Name:        "get_log",
+		Description: "Get commit log starting from a ref, with optional filters",
+		InputSchema: mcp.InputSchema{
+			Type: "object",
+			Properties: map[string]mcp.Property{
+				"ref": {
+					Type:        "string",
+					Description: "Starting ref for the log (default: HEAD)",
+				},
+				"limit": {
+					Type:        "integer",
+					Description: fmt.Sprintf("Maximum number of commits to return (default: 20, max: %d)", Limits.MaxLogEntries),
+					Default:     20,
+				},
+				"author": {
+					Type:        "string",
+					Description: "Filter by author name or email (substring match)",
+				},
+				"since": {
+					Type:        "string",
+					Description: "Stop log at this ref (exclusive)",
+				},
+				"path": {
+					Type:        "string",
+					Description: "Filter commits that affect this path",
+				},
+			},
+		},
+	}
+}
+
+func getCommitInfoTool() mcp.Tool {
+	return mcp.Tool{
+		Name:        "get_commit_info",
+		Description: "Get full details for a specific commit including message, author, and optionally file statistics",
+		InputSchema: mcp.InputSchema{
+			Type: "object",
+			Properties: map[string]mcp.Property{
+				"ref": {
+					Type:        "string",
+					Description: "Commit ref (hash, branch, tag, or HEAD)",
+				},
+				"include_stats": {
+					Type:        "boolean",
+					Description: "Include file change statistics (default: true)",
+					Default:     true,
+				},
+			},
+			Required: []string{"ref"},
+		},
+	}
+}
+
+func getDiffFilesTool() mcp.Tool {
+	return mcp.Tool{
+		Name:        "get_diff_files",
+		Description: "Get list of files changed between two commits with change type and line counts",
+		InputSchema: mcp.InputSchema{
+			Type: "object",
+			Properties: map[string]mcp.Property{
+				"from_ref": {
+					Type:        "string",
+					Description: "Starting commit ref (the older commit)",
+				},
+				"to_ref": {
+					Type:        "string",
+					Description: "Ending commit ref (the newer commit)",
+				},
+			},
+			Required: []string{"from_ref", "to_ref"},
+		},
+	}
+}
+
+func getFileAtCommitTool() mcp.Tool {
+	return mcp.Tool{
+		Name:        "get_file_at_commit",
+		Description: fmt.Sprintf("Get the contents of a file at a specific commit (max %dKB)", Limits.MaxFileContent/1024),
+		InputSchema: mcp.InputSchema{
+			Type: "object",
+			Properties: map[string]mcp.Property{
+				"ref": {
+					Type:        "string",
+					Description: "Commit ref (hash, branch, tag, or HEAD)",
+				},
+				"path": {
+					Type:        "string",
+					Description: "Path to the file relative to repository root",
+				},
+			},
+			Required: []string{"ref", "path"},
+		},
+	}
+}
+
+func isAncestorTool() mcp.Tool {
+	return mcp.Tool{
+		Name:        "is_ancestor",
+		Description: "Check if one commit is an ancestor of another",
+		InputSchema: mcp.InputSchema{
+			Type: "object",
+			Properties: map[string]mcp.Property{
+				"ancestor": {
+					Type:        "string",
+					Description: "Potential ancestor commit ref",
+				},
+				"descendant": {
+					Type:        "string",
+					Description: "Potential descendant commit ref",
+				},
+			},
+			Required: []string{"ancestor", "descendant"},
+		},
+	}
+}
+
+func commitsBetweenTool() mcp.Tool {
+	return mcp.Tool{
+		Name:        "commits_between",
+		Description: "Get all commits between two refs (from is exclusive, to is inclusive)",
+		InputSchema: mcp.InputSchema{
+			Type: "object",
+			Properties: map[string]mcp.Property{
+				"from_ref": {
+					Type:        "string",
+					Description: "Starting commit ref (exclusive - commits after this)",
+				},
+				"to_ref": {
+					Type:        "string",
+					Description: "Ending commit ref (inclusive - up to and including this)",
+				},
+				"limit": {
+					Type:        "integer",
+					Description: fmt.Sprintf("Maximum number of commits (default: %d)", Limits.MaxLogEntries),
+					Default:     Limits.MaxLogEntries,
+				},
+			},
+			Required: []string{"from_ref", "to_ref"},
+		},
+	}
+}
+
+func listBranchesTool() mcp.Tool {
+	return mcp.Tool{
+		Name:        "list_branches",
+		Description: "List all branches in the repository",
+		InputSchema: mcp.InputSchema{
+			Type: "object",
+			Properties: map[string]mcp.Property{
+				"include_remote": {
+					Type:        "boolean",
+					Description: "Include remote-tracking branches (default: false)",
+					Default:     false,
+				},
+			},
+		},
+	}
+}
+
+func searchCommitsTool() mcp.Tool {
+	return mcp.Tool{
+		Name:        "search_commits",
+		Description: "Search commit messages for a pattern (case-insensitive)",
+		InputSchema: mcp.InputSchema{
+			Type: "object",
+			Properties: map[string]mcp.Property{
+				"query": {
+					Type:        "string",
+					Description: "Search pattern to match in commit messages",
+				},
+				"ref": {
+					Type:        "string",
+					Description: "Starting ref for the search (default: HEAD)",
+				},
+				"limit": {
+					Type:        "integer",
+					Description: fmt.Sprintf("Maximum number of results (default: 20, max: %d)", Limits.MaxSearchResult),
+					Default:     20,
+				},
+			},
+			Required: []string{"query"},
+		},
+	}
+}
+
+// Handler constructors
+
+func makeResolveRefHandler(client *GitClient) mcp.ToolHandler {
+	return func(ctx context.Context, args map[string]interface{}) (mcp.CallToolResult, error) {
+		ref, _ := args["ref"].(string)
+		if ref == "" {
+			return mcp.ErrorContent(fmt.Errorf("ref is required")), nil
+		}
+
+		result, err := client.ResolveRef(ref)
+		if err != nil {
+			return mcp.ErrorContent(err), nil
+		}
+
+		return mcp.CallToolResult{
+			Content: []mcp.Content{mcp.TextContent(FormatResolveResult(result))},
+		}, nil
+	}
+}
+
+func makeGetLogHandler(client *GitClient) mcp.ToolHandler {
+	return func(ctx context.Context, args map[string]interface{}) (mcp.CallToolResult, error) {
+		ref := "HEAD"
+		if r, ok := args["ref"].(string); ok && r != "" {
+			ref = r
+		}
+
+		limit := 20
+		if l, ok := args["limit"].(float64); ok && l > 0 {
+			limit = int(l)
+		}
+
+		author, _ := args["author"].(string)
+		since, _ := args["since"].(string)
+		path, _ := args["path"].(string)
+
+		entries, err := client.GetLog(ref, limit, author, since, path)
+		if err != nil {
+			return mcp.ErrorContent(err), nil
+		}
+
+		return mcp.CallToolResult{
+			Content: []mcp.Content{mcp.TextContent(FormatLogEntries(entries))},
+		}, nil
+	}
+}
+
+func makeGetCommitInfoHandler(client *GitClient) mcp.ToolHandler {
+	return func(ctx context.Context, args map[string]interface{}) (mcp.CallToolResult, error) {
+		ref, _ := args["ref"].(string)
+		if ref == "" {
+			return mcp.ErrorContent(fmt.Errorf("ref is required")), nil
+		}
+
+		includeStats := true
+		if s, ok := args["include_stats"].(bool); ok {
+			includeStats = s
+		}
+
+		info, err := client.GetCommitInfo(ref, includeStats)
+		if err != nil {
+			return mcp.ErrorContent(err), nil
+		}
+
+		return mcp.CallToolResult{
+			Content: []mcp.Content{mcp.TextContent(FormatCommitInfo(info))},
+		}, nil
+	}
+}
+
+func makeGetDiffFilesHandler(client *GitClient) mcp.ToolHandler {
+	return func(ctx context.Context, args map[string]interface{}) (mcp.CallToolResult, error) {
+		fromRef, _ := args["from_ref"].(string)
+		if fromRef == "" {
+			return mcp.ErrorContent(fmt.Errorf("from_ref is required")), nil
+		}
+
+		toRef, _ := args["to_ref"].(string)
+		if toRef == "" {
+			return mcp.ErrorContent(fmt.Errorf("to_ref is required")), nil
+		}
+
+		result, err := client.GetDiffFiles(fromRef, toRef)
+		if err != nil {
+			return mcp.ErrorContent(err), nil
+		}
+
+		return mcp.CallToolResult{
+			Content: []mcp.Content{mcp.TextContent(FormatDiffResult(result))},
+		}, nil
+	}
+}
+
+func makeGetFileAtCommitHandler(client *GitClient) mcp.ToolHandler {
+	return func(ctx context.Context, args map[string]interface{}) (mcp.CallToolResult, error) {
+		ref, _ := args["ref"].(string)
+		if ref == "" {
+			return mcp.ErrorContent(fmt.Errorf("ref is required")), nil
+		}
+
+		path, _ := args["path"].(string)
+		if path == "" {
+			return mcp.ErrorContent(fmt.Errorf("path is required")), nil
+		}
+
+		content, err := client.GetFileAtCommit(ref, path)
+		if err != nil {
+			return mcp.ErrorContent(err), nil
+		}
+
+		return mcp.CallToolResult{
+			Content: []mcp.Content{mcp.TextContent(FormatFileContent(content))},
+		}, nil
+	}
+}
+
+func makeIsAncestorHandler(client *GitClient) mcp.ToolHandler {
+	return func(ctx context.Context, args map[string]interface{}) (mcp.CallToolResult, error) {
+		ancestor, _ := args["ancestor"].(string)
+		if ancestor == "" {
+			return mcp.ErrorContent(fmt.Errorf("ancestor is required")), nil
+		}
+
+		descendant, _ := args["descendant"].(string)
+		if descendant == "" {
+			return mcp.ErrorContent(fmt.Errorf("descendant is required")), nil
+		}
+
+		result, err := client.IsAncestor(ancestor, descendant)
+		if err != nil {
+			return mcp.ErrorContent(err), nil
+		}
+
+		return mcp.CallToolResult{
+			Content: []mcp.Content{mcp.TextContent(FormatAncestryResult(result))},
+		}, nil
+	}
+}
+
+func makeCommitsBetweenHandler(client *GitClient) mcp.ToolHandler {
+	return func(ctx context.Context, args map[string]interface{}) (mcp.CallToolResult, error) {
+		fromRef, _ := args["from_ref"].(string)
+		if fromRef == "" {
+			return mcp.ErrorContent(fmt.Errorf("from_ref is required")), nil
+		}
+
+		toRef, _ := args["to_ref"].(string)
+		if toRef == "" {
+			return mcp.ErrorContent(fmt.Errorf("to_ref is required")), nil
+		}
+
+		limit := Limits.MaxLogEntries
+		if l, ok := args["limit"].(float64); ok && l > 0 {
+			limit = int(l)
+		}
+
+		result, err := client.CommitsBetween(fromRef, toRef, limit)
+		if err != nil {
+			return mcp.ErrorContent(err), nil
+		}
+
+		return mcp.CallToolResult{
+			Content: []mcp.Content{mcp.TextContent(FormatCommitRange(result))},
+		}, nil
+	}
+}
+
+func makeListBranchesHandler(client *GitClient) mcp.ToolHandler {
+	return func(ctx context.Context, args map[string]interface{}) (mcp.CallToolResult, error) {
+		includeRemote := false
+		if r, ok := args["include_remote"].(bool); ok {
+			includeRemote = r
+		}
+
+		result, err := client.ListBranches(includeRemote)
+		if err != nil {
+			return mcp.ErrorContent(err), nil
+		}
+
+		return mcp.CallToolResult{
+			Content: []mcp.Content{mcp.TextContent(FormatBranchList(result))},
+		}, nil
+	}
+}
+
+func makeSearchCommitsHandler(client *GitClient) mcp.ToolHandler {
+	return func(ctx context.Context, args map[string]interface{}) (mcp.CallToolResult, error) {
+		query, _ := args["query"].(string)
+		if query == "" {
+			return mcp.ErrorContent(fmt.Errorf("query is required")), nil
+		}
+
+		ref := "HEAD"
+		if r, ok := args["ref"].(string); ok && r != "" {
+			ref = r
+		}
+
+		limit := 20
+		if l, ok := args["limit"].(float64); ok && l > 0 {
+			limit = int(l)
+		}
+
+		result, err := client.SearchCommits(ref, query, limit)
+		if err != nil {
+			return mcp.ErrorContent(err), nil
+		}
+
+		return mcp.CallToolResult{
+			Content: []mcp.Content{mcp.TextContent(FormatSearchResult(result))},
+		}, nil
+	}
+}
--- a/internal/gitexplorer/types.go
+++ b/internal/gitexplorer/types.go
@@ -0,0 +1,121 @@
+package gitexplorer
+
+import (
+	"time"
+)
+
+// ResolveResult contains the result of resolving a ref to a commit.
+type ResolveResult struct {
+	Ref    string `json:"ref"`
+	Commit string `json:"commit"`
+	Type   string `json:"type"` // "branch", "tag", "commit"
+}
+
+// LogEntry represents a single commit in the log.
+type LogEntry struct {
+	Hash      string    `json:"hash"`
+	ShortHash string    `json:"short_hash"`
+	Author    string    `json:"author"`
+	Email     string    `json:"email"`
+	Date      time.Time `json:"date"`
+	Subject   string    `json:"subject"`
+}
+
+// CommitInfo contains full details about a commit.
+type CommitInfo struct {
+	Hash       string     `json:"hash"`
+	Author     string     `json:"author"`
+	Email      string     `json:"email"`
+	Date       time.Time  `json:"date"`
+	Committer  string     `json:"committer"`
+	CommitDate time.Time  `json:"commit_date"`
+	Message    string     `json:"message"`
+	Parents    []string   `json:"parents"`
+	Stats      *FileStats `json:"stats,omitempty"`
+}
+
+// FileStats contains statistics about file changes.
+type FileStats struct {
+	FilesChanged int `json:"files_changed"`
+	Additions    int `json:"additions"`
+	Deletions    int `json:"deletions"`
+}
+
+// DiffFile represents a file changed between two commits.
+type DiffFile struct {
+	Path      string `json:"path"`
+	OldPath   string `json:"old_path,omitempty"` // For renames
+	Status    string `json:"status"`             // "added", "modified", "deleted", "renamed"
+	Additions int    `json:"additions"`
+	Deletions int    `json:"deletions"`
+}
+
+// DiffResult contains the list of files changed between two commits.
+type DiffResult struct {
+	FromCommit string     `json:"from_commit"`
+	ToCommit   string     `json:"to_commit"`
+	Files      []DiffFile `json:"files"`
+}
+
+// FileContent represents the content of a file at a specific commit.
+type FileContent struct {
+	Path    string `json:"path"`
+	Commit  string `json:"commit"`
+	Size    int64  `json:"size"`
+	Content string `json:"content"`
+}
+
+// AncestryResult contains the result of an ancestry check.
+type AncestryResult struct {
+	Ancestor   string `json:"ancestor"`
+	Descendant string `json:"descendant"`
+	IsAncestor bool   `json:"is_ancestor"`
+}
+
+// CommitRange represents commits between two refs.
+type CommitRange struct {
+	FromCommit string     `json:"from_commit"`
+	ToCommit   string     `json:"to_commit"`
+	Commits    []LogEntry `json:"commits"`
+	Count      int        `json:"count"`
+}
+
+// Branch represents a git branch.
+type Branch struct {
+	Name     string `json:"name"`
+	Commit   string `json:"commit"`
+	IsRemote bool   `json:"is_remote"`
+	IsHead   bool   `json:"is_head"`
+	Upstream string `json:"upstream,omitempty"`
+	AheadBy  int    `json:"ahead_by,omitempty"`
+	BehindBy int    `json:"behind_by,omitempty"`
+}
+
+// BranchList contains the list of branches.
+type BranchList struct {
+	Branches []Branch `json:"branches"`
+	Current  string   `json:"current"`
+	Total    int      `json:"total"`
+}
+
+// SearchResult represents a commit matching a search query.
+type SearchResult struct {
+	Commits []LogEntry `json:"commits"`
+	Query   string     `json:"query"`
+	Count   int        `json:"count"`
+}
+
+// Limits defines the maximum values for various operations.
+var Limits = struct {
+	MaxFileContent  int64 // Maximum file size in bytes
+	MaxLogEntries   int   // Maximum commit log entries
+	MaxBranches     int   // Maximum branches to list
+	MaxDiffFiles    int   // Maximum files in diff
+	MaxSearchResult int   // Maximum search results
+}{
+	MaxFileContent:  100 * 1024, // 100KB
+	MaxLogEntries:   100,
+	MaxBranches:     500,
+	MaxDiffFiles:    1000,
+	MaxSearchResult: 100,
+}
--- a/internal/gitexplorer/validation.go
+++ b/internal/gitexplorer/validation.go
@@ -0,0 +1,57 @@
+package gitexplorer
+
+import (
+	"errors"
+	"path/filepath"
+	"slices"
+	"strings"
+)
+
+var (
+	// ErrPathTraversal is returned when a path attempts to traverse outside the repository.
+	ErrPathTraversal = errors.New("path traversal not allowed")
+	// ErrAbsolutePath is returned when an absolute path is provided.
+	ErrAbsolutePath = errors.New("absolute paths not allowed")
+	// ErrNullByte is returned when a path contains null bytes.
+	ErrNullByte = errors.New("null bytes not allowed in path")
+	// ErrEmptyPath is returned when a path is empty.
+	ErrEmptyPath = errors.New("path cannot be empty")
+)
+
+// ValidatePath validates a file path for security.
+// It rejects:
+// - Absolute paths
+// - Paths containing null bytes
+// - Paths that attempt directory traversal (contain "..")
+// - Empty paths
+func ValidatePath(path string) error {
+	if path == "" {
+		return ErrEmptyPath
+	}
+
+	// Check for null bytes
+	if strings.Contains(path, "\x00") {
+		return ErrNullByte
+	}
+
+	// Check for absolute paths
+	if filepath.IsAbs(path) {
+		return ErrAbsolutePath
+	}
+
+	// Clean the path and check for traversal
+	cleaned := filepath.Clean(path)
+
+	// Check if cleaned path starts with ".."
+	if strings.HasPrefix(cleaned, "..") {
+		return ErrPathTraversal
+	}
+
+	// Check for ".." components in the path
+	parts := strings.Split(cleaned, string(filepath.Separator))
+	if slices.Contains(parts, "..") {
+		return ErrPathTraversal
+	}
+
+	return nil
+}
--- a/internal/gitexplorer/validation_test.go
+++ b/internal/gitexplorer/validation_test.go
@@ -0,0 +1,91 @@
+package gitexplorer
+
+import (
+	"testing"
+)
+
+func TestValidatePath(t *testing.T) {
+	tests := []struct {
+		name    string
+		path    string
+		wantErr error
+	}{
+		// Valid paths
+		{
+			name:    "simple file",
+			path:    "README.md",
+			wantErr: nil,
+		},
+		{
+			name:    "nested file",
+			path:    "internal/gitexplorer/types.go",
+			wantErr: nil,
+		},
+		{
+			name:    "file with dots",
+			path:    "file.test.go",
+			wantErr: nil,
+		},
+		{
+			name:    "current dir prefix",
+			path:    "./README.md",
+			wantErr: nil,
+		},
+		{
+			name:    "deeply nested",
+			path:    "a/b/c/d/e/f/g.txt",
+			wantErr: nil,
+		},
+
+		// Invalid paths
+		{
+			name:    "empty path",
+			path:    "",
+			wantErr: ErrEmptyPath,
+		},
+		{
+			name:    "absolute path unix",
+			path:    "/etc/passwd",
+			wantErr: ErrAbsolutePath,
+		},
+		{
+			name:    "parent dir traversal simple",
+			path:    "../secret.txt",
+			wantErr: ErrPathTraversal,
+		},
+		{
+			name:    "parent dir traversal nested",
+			path:    "foo/../../../etc/passwd",
+			wantErr: ErrPathTraversal,
+		},
+		{
+			name:    "parent dir traversal in middle",
+			path:    "foo/bar/../../../secret",
+			wantErr: ErrPathTraversal,
+		},
+		{
+			name:    "null byte",
+			path:    "file\x00.txt",
+			wantErr: ErrNullByte,
+		},
+		{
+			name:    "null byte in middle",
+			path:    "foo/bar\x00baz/file.txt",
+			wantErr: ErrNullByte,
+		},
+		{
+			name:    "double dot only",
+			path:    "..",
+			wantErr: ErrPathTraversal,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			err := ValidatePath(tt.path)
+			if err != tt.wantErr {
+				t.Errorf("ValidatePath(%q) = %v, want %v", tt.path, err, tt.wantErr)
+			}
+		})
+	}
+}
--- a/internal/homemanager/indexer.go
+++ b/internal/homemanager/indexer.go
@@ -15,9 +15,9 @@ import (
 	"strings"
 	"time"

-	"git.t-juice.club/torjus/labmcp/internal/database"
-	"git.t-juice.club/torjus/labmcp/internal/nixos"
-	"git.t-juice.club/torjus/labmcp/internal/options"
+	"code.t-juice.club/torjus/labmcp/internal/database"
+	"code.t-juice.club/torjus/labmcp/internal/nixos"
+	"code.t-juice.club/torjus/labmcp/internal/options"
 )

 // revisionPattern validates revision strings to prevent injection attacks.
--- a/internal/homemanager/indexer_test.go
+++ b/internal/homemanager/indexer_test.go
@@ -6,7 +6,7 @@ import (
 	"testing"
 	"time"

-	"git.t-juice.club/torjus/labmcp/internal/database"
+	"code.t-juice.club/torjus/labmcp/internal/database"
 )

 // TestHomeManagerRevision is a known release branch for testing.
--- a/internal/mcp/handlers.go
+++ b/internal/mcp/handlers.go
@@ -8,18 +8,35 @@ import (
 	"strings"
 	"time"

-	"git.t-juice.club/torjus/labmcp/internal/database"
-	"git.t-juice.club/torjus/labmcp/internal/options"
-	"git.t-juice.club/torjus/labmcp/internal/packages"
+	"code.t-juice.club/torjus/labmcp/internal/database"
+	"code.t-juice.club/torjus/labmcp/internal/options"
+	"code.t-juice.club/torjus/labmcp/internal/packages"
 )

 // RegisterHandlers registers all tool handlers on the server for options mode.
+// Used by legacy nixos-options and hm-options servers (no package indexing).
 func (s *Server) RegisterHandlers(indexer options.Indexer) {
+	s.registerOptionsHandlers(indexer, nil)
+}
+
+// RegisterHandlersWithPackages registers all tool handlers for options mode
+// with additional package indexing support. When pkgIndexer is non-nil,
+// index_revision will also index packages, and list_revisions will show package counts.
+func (s *Server) RegisterHandlersWithPackages(indexer options.Indexer, pkgIndexer *packages.Indexer) {
+	s.registerOptionsHandlers(indexer, pkgIndexer)
+}
+
+// registerOptionsHandlers is the shared implementation for RegisterHandlers and RegisterHandlersWithPackages.
+func (s *Server) registerOptionsHandlers(indexer options.Indexer, pkgIndexer *packages.Indexer) {
 	s.tools["search_options"] = s.handleSearchOptions
 	s.tools["get_option"] = s.handleGetOption
 	s.tools["get_file"] = s.handleGetFile
-	s.tools["index_revision"] = s.makeIndexHandler(indexer)
-	s.tools["list_revisions"] = s.handleListRevisions
+	s.tools["index_revision"] = s.makeIndexHandler(indexer, pkgIndexer)
+	if pkgIndexer != nil {
+		s.tools["list_revisions"] = s.handleListRevisionsWithPackages
+	} else {
+		s.tools["list_revisions"] = s.handleListRevisions
+	}
 	s.tools["delete_revision"] = s.handleDeleteRevision
 }

@@ -28,6 +45,7 @@ func (s *Server) RegisterPackageHandlers(pkgIndexer *packages.Indexer) {
 	s.tools["search_packages"] = s.handleSearchPackages
 	s.tools["get_package"] = s.handleGetPackage
 	s.tools["get_file"] = s.handleGetFile
+	s.tools["index_revision"] = s.makePackageIndexHandler(pkgIndexer)
 	s.tools["list_revisions"] = s.handleListRevisionsWithPackages
 	s.tools["delete_revision"] = s.handleDeleteRevision
 }
@@ -246,7 +264,8 @@ func (s *Server) handleGetFile(ctx context.Context, args map[string]interface{})
 }

 // makeIndexHandler creates the index_revision handler with the indexer.
-func (s *Server) makeIndexHandler(indexer options.Indexer) ToolHandler {
+// If pkgIndexer is non-nil, it will also index packages after options and files.
+func (s *Server) makeIndexHandler(indexer options.Indexer, pkgIndexer *packages.Indexer) ToolHandler {
 	return func(ctx context.Context, args map[string]interface{}) (CallToolResult, error) {
 		revision, _ := args["revision"].(string)
 		if revision == "" {
@@ -278,6 +297,17 @@ func (s *Server) makeIndexHandler(indexer options.Indexer) ToolHandler {
 			s.logger.Printf("Warning: file indexing failed: %v", err)
 		}

+		// Index packages if package indexer is available
+		var packageCount int
+		if pkgIndexer != nil {
+			pkgResult, pkgErr := pkgIndexer.IndexPackages(ctx, result.Revision.ID, result.Revision.GitHash)
+			if pkgErr != nil {
+				s.logger.Printf("Warning: package indexing failed: %v", pkgErr)
+			} else {
+				packageCount = pkgResult.PackageCount
+			}
+		}
+
 		var sb strings.Builder
 		sb.WriteString(fmt.Sprintf("Indexed revision: %s\n", result.Revision.GitHash))
 		if result.Revision.ChannelName != "" {
@@ -285,6 +315,9 @@ func (s *Server) makeIndexHandler(indexer options.Indexer) ToolHandler {
 		}
 		sb.WriteString(fmt.Sprintf("Options: %d\n", result.OptionCount))
 		sb.WriteString(fmt.Sprintf("Files: %d\n", fileCount))
+		if packageCount > 0 {
+			sb.WriteString(fmt.Sprintf("Packages: %d\n", packageCount))
+		}
 		// Handle Duration which may be time.Duration or interface{}
 		if dur, ok := result.Duration.(time.Duration); ok {
 			sb.WriteString(fmt.Sprintf("Duration: %s\n", dur.Round(time.Millisecond)))
@@ -296,6 +329,85 @@ func (s *Server) makeIndexHandler(indexer options.Indexer) ToolHandler {
 	}
 }

+// makePackageIndexHandler creates an index_revision handler for the packages-only server.
+// It creates a revision record if needed, then indexes packages.
+func (s *Server) makePackageIndexHandler(pkgIndexer *packages.Indexer) ToolHandler {
+	return func(ctx context.Context, args map[string]interface{}) (CallToolResult, error) {
+		revision, _ := args["revision"].(string)
+		if revision == "" {
+			return ErrorContent(fmt.Errorf("revision is required")), nil
+		}
+
+		if err := packages.ValidateRevision(revision); err != nil {
+			return ErrorContent(err), nil
+		}
+
+		// Resolve channel aliases to git ref
+		ref := pkgIndexer.ResolveRevision(revision)
+
+		// Check if revision already exists
+		rev, err := s.store.GetRevision(ctx, ref)
+		if err != nil {
+			return ErrorContent(fmt.Errorf("failed to check revision: %w", err)), nil
+		}
+
+		if rev == nil {
+			// Also try by channel name
+			rev, err = s.store.GetRevisionByChannel(ctx, revision)
+			if err != nil {
+				return ErrorContent(fmt.Errorf("failed to check revision: %w", err)), nil
+			}
+		}
+
+		if rev == nil {
+			// Create a new revision record
+			commitDate, _ := pkgIndexer.GetCommitDate(ctx, ref)
+			rev = &database.Revision{
+				GitHash:     ref,
+				ChannelName: pkgIndexer.GetChannelName(revision),
+				CommitDate:  commitDate,
+			}
+			if err := s.store.CreateRevision(ctx, rev); err != nil {
+				return ErrorContent(fmt.Errorf("failed to create revision: %w", err)), nil
+			}
+		}
+
+		// Check if packages are already indexed for this revision
+		if rev.PackageCount > 0 {
+			var sb strings.Builder
+			sb.WriteString(fmt.Sprintf("Revision already indexed: %s\n", rev.GitHash))
+			if rev.ChannelName != "" {
+				sb.WriteString(fmt.Sprintf("Channel: %s\n", rev.ChannelName))
+			}
+			sb.WriteString(fmt.Sprintf("Packages: %d\n", rev.PackageCount))
+			sb.WriteString(fmt.Sprintf("Indexed at: %s\n", rev.IndexedAt.Format("2006-01-02 15:04")))
+			return CallToolResult{
+				Content: []Content{TextContent(sb.String())},
+			}, nil
+		}
+
+		// Index packages
+		pkgResult, err := pkgIndexer.IndexPackages(ctx, rev.ID, rev.GitHash)
+		if err != nil {
+			return ErrorContent(fmt.Errorf("package indexing failed: %w", err)), nil
+		}
+
+		var sb strings.Builder
+		sb.WriteString(fmt.Sprintf("Indexed revision: %s\n", rev.GitHash))
+		if rev.ChannelName != "" {
+			sb.WriteString(fmt.Sprintf("Channel: %s\n", rev.ChannelName))
+		}
+		sb.WriteString(fmt.Sprintf("Packages: %d\n", pkgResult.PackageCount))
+		if dur, ok := pkgResult.Duration.(time.Duration); ok {
+			sb.WriteString(fmt.Sprintf("Duration: %s\n", dur.Round(time.Millisecond)))
+		}
+
+		return CallToolResult{
+			Content: []Content{TextContent(sb.String())},
+		}, nil
+	}
+}
+
 // handleListRevisions handles the list_revisions tool.
 func (s *Server) handleListRevisions(ctx context.Context, args map[string]interface{}) (CallToolResult, error) {
 	revisions, err := s.store.ListRevisions(ctx)
--- a/internal/mcp/server.go
+++ b/internal/mcp/server.go
@@ -7,7 +7,7 @@ import (
 	"io"
 	"log"

-	"git.t-juice.club/torjus/labmcp/internal/database"
+	"code.t-juice.club/torjus/labmcp/internal/database"
 )

 // ServerMode indicates which type of tools the server should expose.
@@ -45,7 +45,7 @@ type ServerConfig struct {
 func DefaultNixOSConfig() ServerConfig {
 	return ServerConfig{
 		Name:           "nixos-options",
-		Version:        "0.3.0",
+		Version:        "0.4.0",
 		DefaultChannel: "nixos-stable",
 		SourceName:     "nixpkgs",
 		Mode:           ModeOptions,
@@ -57,7 +57,9 @@ If the current project contains a flake.lock file, you can index the exact nixpk

 Example: If flake.lock contains "rev": "abc123...", call index_revision with revision "abc123...".

-This ensures option documentation matches the nixpkgs version the project actually uses.`,
+This ensures option documentation matches the nixpkgs version the project actually uses.
+
+Note: index_revision also indexes packages when available, so both options and packages become searchable.`,
 	}
 }

@@ -65,7 +67,7 @@ This ensures option documentation matches the nixpkgs version the project actual
 func DefaultNixpkgsPackagesConfig() ServerConfig {
 	return ServerConfig{
 		Name:           "nixpkgs-packages",
-		Version:        "0.3.0",
+		Version:        "0.4.0",
 		DefaultChannel: "nixos-stable",
 		SourceName:     "nixpkgs",
 		Mode:           ModePackages,
@@ -73,7 +75,9 @@ func DefaultNixpkgsPackagesConfig() ServerConfig {

 If the current project contains a flake.lock file, you can search packages from the exact nixpkgs revision used by the project:
 1. Read the flake.lock file to find the nixpkgs "rev" field
-2. Ensure the revision is indexed (packages are indexed separately from options)
+2. Call index_revision with that git hash to index packages for that specific version
+
+Example: If flake.lock contains "rev": "abc123...", call index_revision with revision "abc123...".

 This ensures package information matches the nixpkgs version the project actually uses.`,
 	}
@@ -83,7 +87,7 @@ This ensures package information matches the nixpkgs version the project actuall
 func DefaultMonitoringConfig() ServerConfig {
 	return ServerConfig{
 		Name:    "lab-monitoring",
-		Version: "0.3.0",
+		Version: "0.3.1",
 		Mode:    ModeCustom,
 		Instructions: `Lab Monitoring MCP Server - Query Prometheus metrics and Alertmanager alerts.

@@ -118,6 +122,27 @@ This ensures option documentation matches the home-manager version the project a
 	}
 }

+// DefaultGitExplorerConfig returns the default configuration for the git-explorer server.
+func DefaultGitExplorerConfig() ServerConfig {
+	return ServerConfig{
+		Name:    "git-explorer",
+		Version: "0.1.0",
+		Mode:    ModeCustom,
+		Instructions: `Git Explorer MCP Server - Read-only access to git repository information.
+
+Tools for exploring git repositories:
+- Resolve refs (branches, tags, commits) to commit hashes
+- View commit logs with filtering by author, path, or range
+- Get full commit details including file change statistics
+- Compare commits to see which files changed
+- Read file contents at any commit
+- Check ancestry relationships between commits
+- Search commit messages
+
+All operations are read-only and will never modify the repository.`,
+	}
+}
+
 // Server is an MCP server that handles JSON-RPC requests.
 type Server struct {
 	store       database.Store
@@ -406,7 +431,7 @@ func (s *Server) getOptionToolDefinitions() []Tool {
 		},
 		{
 			Name:        "index_revision",
-			Description: fmt.Sprintf("Index a %s revision to make its options searchable", sourceRepo),
+			Description: s.indexRevisionDescription(sourceRepo),
 			InputSchema: InputSchema{
 				Type: "object",
 				Properties: map[string]Property{
@@ -443,6 +468,15 @@ func (s *Server) getOptionToolDefinitions() []Tool {
 	}
 }

+// indexRevisionDescription returns the description for the index_revision tool,
+// adjusted based on whether packages are also indexed.
+func (s *Server) indexRevisionDescription(sourceRepo string) string {
+	if s.config.SourceName == "nixpkgs" {
+		return fmt.Sprintf("Index a %s revision to make its options and packages searchable", sourceRepo)
+	}
+	return fmt.Sprintf("Index a %s revision to make its options searchable", sourceRepo)
+}
+
 // getPackageToolDefinitions returns the tool definitions for packages mode.
 func (s *Server) getPackageToolDefinitions() []Tool {
 	exampleChannels := "'nixos-unstable', 'nixos-24.05'"
@@ -526,6 +560,20 @@ func (s *Server) getPackageToolDefinitions() []Tool {
 				Required: []string{"path"},
 			},
 		},
+		{
+			Name:        "index_revision",
+			Description: "Index a nixpkgs revision to make its packages searchable",
+			InputSchema: InputSchema{
+				Type: "object",
+				Properties: map[string]Property{
+					"revision": {
+						Type:        "string",
+						Description: fmt.Sprintf("Git hash (full or short) or channel name (e.g., %s)", exampleChannels),
+					},
+				},
+				Required: []string{"revision"},
+			},
+		},
 		{
 			Name:        "list_revisions",
 			Description: "List all indexed nixpkgs revisions",
--- a/internal/mcp/server_test.go
+++ b/internal/mcp/server_test.go
@@ -8,8 +8,9 @@ import (
 	"strings"
 	"testing"

-	"git.t-juice.club/torjus/labmcp/internal/database"
-	"git.t-juice.club/torjus/labmcp/internal/nixos"
+	"code.t-juice.club/torjus/labmcp/internal/database"
+	"code.t-juice.club/torjus/labmcp/internal/nixos"
+	"code.t-juice.club/torjus/labmcp/internal/packages"
 )

 func TestServerInitialize(t *testing.T) {
@@ -145,6 +146,110 @@ func TestServerNotification(t *testing.T) {
 	}
 }

+func TestPackagesServerToolsList(t *testing.T) {
+	store := setupTestStore(t)
+	server := NewServer(store, nil, DefaultNixpkgsPackagesConfig())
+
+	pkgIndexer := packages.NewIndexer(store)
+	server.RegisterPackageHandlers(pkgIndexer)
+
+	input := `{"jsonrpc":"2.0","id":1,"method":"tools/list"}`
+
+	resp := runRequest(t, server, input)
+
+	if resp.Error != nil {
+		t.Fatalf("Unexpected error: %v", resp.Error)
+	}
+
+	result, ok := resp.Result.(map[string]interface{})
+	if !ok {
+		t.Fatalf("Expected map result, got %T", resp.Result)
+	}
+
+	tools, ok := result["tools"].([]interface{})
+	if !ok {
+		t.Fatalf("Expected tools array, got %T", result["tools"])
+	}
+
+	// Should have 6 tools (search_packages, get_package, get_file, index_revision, list_revisions, delete_revision)
+	if len(tools) != 6 {
+		t.Errorf("Expected 6 tools, got %d", len(tools))
+	}
+
+	expectedTools := map[string]bool{
+		"search_packages": false,
+		"get_package":     false,
+		"get_file":        false,
+		"index_revision":  false,
+		"list_revisions":  false,
+		"delete_revision": false,
+	}
+
+	for _, tool := range tools {
+		toolMap := tool.(map[string]interface{})
+		name := toolMap["name"].(string)
+		if _, ok := expectedTools[name]; ok {
+			expectedTools[name] = true
+		}
+	}
+
+	for name, found := range expectedTools {
+		if !found {
+			t.Errorf("Tool %q not found in tools list", name)
+		}
+	}
+}
+
+func TestOptionsServerWithPackagesToolsList(t *testing.T) {
+	store := setupTestStore(t)
+	server := NewServer(store, nil, DefaultNixOSConfig())
+
+	indexer := nixos.NewIndexer(store)
+	pkgIndexer := packages.NewIndexer(store)
+	server.RegisterHandlersWithPackages(indexer, pkgIndexer)
+
+	input := `{"jsonrpc":"2.0","id":1,"method":"tools/list"}`
+
+	resp := runRequest(t, server, input)
+
+	if resp.Error != nil {
+		t.Fatalf("Unexpected error: %v", resp.Error)
+	}
+
+	result, ok := resp.Result.(map[string]interface{})
+	if !ok {
+		t.Fatalf("Expected map result, got %T", resp.Result)
+	}
+
+	tools, ok := result["tools"].([]interface{})
+	if !ok {
+		t.Fatalf("Expected tools array, got %T", result["tools"])
+	}
+
+	// Should still have 6 tools (same as options-only)
+	if len(tools) != 6 {
+		t.Errorf("Expected 6 tools, got %d", len(tools))
+	}
+
+	// Verify index_revision is present
+	found := false
+	for _, tool := range tools {
+		toolMap := tool.(map[string]interface{})
+		if toolMap["name"].(string) == "index_revision" {
+			found = true
+			// For nixpkgs source, description should mention packages
+			desc := toolMap["description"].(string)
+			if !strings.Contains(desc, "packages") {
+				t.Errorf("index_revision description should mention packages, got: %s", desc)
+			}
+			break
+		}
+	}
+	if !found {
+		t.Error("index_revision tool not found in tools list")
+	}
+}
+
 func TestGetFilePathValidation(t *testing.T) {
 	store := setupTestStore(t)
 	server := setupTestServer(t, store)
--- a/internal/monitoring/handlers.go
+++ b/internal/monitoring/handlers.go
@@ -7,7 +7,7 @@ import (
 	"strings"
 	"time"

-	"git.t-juice.club/torjus/labmcp/internal/mcp"
+	"code.t-juice.club/torjus/labmcp/internal/mcp"
 )

 // AlertSummary queries Alertmanager for active (non-silenced) alerts and returns
--- a/internal/monitoring/handlers_test.go
+++ b/internal/monitoring/handlers_test.go
@@ -10,7 +10,7 @@ import (
 	"strings"
 	"testing"

-	"git.t-juice.club/torjus/labmcp/internal/mcp"
+	"code.t-juice.club/torjus/labmcp/internal/mcp"
 )

 // setupTestServer creates a test MCP server with monitoring handlers backed by test HTTP servers.
@@ -31,7 +31,7 @@ func setupTestServer(t *testing.T, promHandler, amHandler http.HandlerFunc, loki
 	var lokiSrv *httptest.Server
 	if len(lokiHandler) > 0 && lokiHandler[0] != nil {
 		lokiSrv = httptest.NewServer(lokiHandler[0])
-		loki = NewLokiClient(lokiSrv.URL)
+		loki = NewLokiClient(LokiClientOptions{BaseURL: lokiSrv.URL})
 	}

 	RegisterHandlers(server, prom, am, loki, HandlerOptions{EnableSilences: true})
--- a/internal/monitoring/loki.go
+++ b/internal/monitoring/loki.go
@@ -11,16 +11,27 @@ import (
 	"time"
 )

+// LokiClientOptions configures the Loki client.
+type LokiClientOptions struct {
+	BaseURL  string
+	Username string
+	Password string
+}
+
 // LokiClient is an HTTP client for the Loki API.
 type LokiClient struct {
 	baseURL    string
+	username   string
+	password   string
 	httpClient *http.Client
 }

 // NewLokiClient creates a new Loki API client.
-func NewLokiClient(baseURL string) *LokiClient {
+func NewLokiClient(opts LokiClientOptions) *LokiClient {
 	return &LokiClient{
-		baseURL: strings.TrimRight(baseURL, "/"),
+		baseURL:  strings.TrimRight(opts.BaseURL, "/"),
+		username: opts.Username,
+		password: opts.Password,
 		httpClient: &http.Client{
 			Timeout: 30 * time.Second,
 		},
@@ -94,6 +105,10 @@ func (c *LokiClient) get(ctx context.Context, path string, params url.Values) (j
 		return nil, fmt.Errorf("failed to create request: %w", err)
 	}

+	if c.username != "" {
+		req.SetBasicAuth(c.username, c.password)
+	}
+
 	resp, err := c.httpClient.Do(req)
 	if err != nil {
 		return nil, fmt.Errorf("request failed: %w", err)
--- a/internal/monitoring/loki_test.go
+++ b/internal/monitoring/loki_test.go
@@ -42,7 +42,7 @@ func TestLokiClient_QueryRange(t *testing.T) {
 	}))
 	defer srv.Close()

-	client := NewLokiClient(srv.URL)
+	client := NewLokiClient(LokiClientOptions{BaseURL: srv.URL})
 	start := time.Unix(0, 1234567890000000000)
 	end := time.Unix(0, 1234567899000000000)
 	data, err := client.QueryRange(context.Background(), `{job="varlogs"}`, start, end, 10, "backward")
@@ -78,7 +78,7 @@ func TestLokiClient_QueryRangeError(t *testing.T) {
 	}))
 	defer srv.Close()

-	client := NewLokiClient(srv.URL)
+	client := NewLokiClient(LokiClientOptions{BaseURL: srv.URL})
 	_, err := client.QueryRange(context.Background(), "invalid{", time.Now().Add(-time.Hour), time.Now(), 100, "backward")
 	if err == nil {
 		t.Fatal("expected error, got nil")
@@ -102,7 +102,7 @@ func TestLokiClient_Labels(t *testing.T) {
 	}))
 	defer srv.Close()

-	client := NewLokiClient(srv.URL)
+	client := NewLokiClient(LokiClientOptions{BaseURL: srv.URL})
 	labels, err := client.Labels(context.Background())
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
@@ -130,7 +130,7 @@ func TestLokiClient_LabelValues(t *testing.T) {
 	}))
 	defer srv.Close()

-	client := NewLokiClient(srv.URL)
+	client := NewLokiClient(LokiClientOptions{BaseURL: srv.URL})
 	values, err := client.LabelValues(context.Background(), "job")
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
@@ -144,6 +144,65 @@ func TestLokiClient_LabelValues(t *testing.T) {
 	}
 }

+func TestLokiClient_BasicAuth(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		user, pass, ok := r.BasicAuth()
+		if !ok {
+			t.Error("expected basic auth to be set")
+		}
+		if user != "myuser" {
+			t.Errorf("expected username=myuser, got %s", user)
+		}
+		if pass != "mypass" {
+			t.Errorf("expected password=mypass, got %s", pass)
+		}
+
+		w.Header().Set("Content-Type", "application/json")
+		_, _ = w.Write([]byte(`{
+			"status": "success",
+			"data": ["job"]
+		}`))
+	}))
+	defer srv.Close()
+
+	client := NewLokiClient(LokiClientOptions{
+		BaseURL:  srv.URL,
+		Username: "myuser",
+		Password: "mypass",
+	})
+	labels, err := client.Labels(context.Background())
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(labels) != 1 || labels[0] != "job" {
+		t.Errorf("unexpected labels: %v", labels)
+	}
+}
+
+func TestLokiClient_NoAuthWhenNoCredentials(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if _, _, ok := r.BasicAuth(); ok {
+			t.Error("expected no basic auth header, but it was set")
+		}
+
+		w.Header().Set("Content-Type", "application/json")
+		_, _ = w.Write([]byte(`{
+			"status": "success",
+			"data": ["job"]
+		}`))
+	}))
+	defer srv.Close()
+
+	client := NewLokiClient(LokiClientOptions{BaseURL: srv.URL})
+	labels, err := client.Labels(context.Background())
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(labels) != 1 || labels[0] != "job" {
+		t.Errorf("unexpected labels: %v", labels)
+	}
+}
+
 func TestLokiClient_HTTPError(t *testing.T) {
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.WriteHeader(http.StatusInternalServerError)
@@ -151,7 +210,7 @@ func TestLokiClient_HTTPError(t *testing.T) {
 	}))
 	defer srv.Close()

-	client := NewLokiClient(srv.URL)
+	client := NewLokiClient(LokiClientOptions{BaseURL: srv.URL})
 	_, err := client.QueryRange(context.Background(), `{job="test"}`, time.Now().Add(-time.Hour), time.Now(), 100, "backward")
 	if err == nil {
 		t.Fatal("expected error, got nil")
--- a/internal/nixos/indexer.go
+++ b/internal/nixos/indexer.go
@@ -15,8 +15,8 @@ import (
 	"strings"
 	"time"

-	"git.t-juice.club/torjus/labmcp/internal/database"
-	"git.t-juice.club/torjus/labmcp/internal/options"
+	"code.t-juice.club/torjus/labmcp/internal/database"
+	"code.t-juice.club/torjus/labmcp/internal/options"
 )

 // revisionPattern validates revision strings to prevent injection attacks.
--- a/internal/nixos/indexer_test.go
+++ b/internal/nixos/indexer_test.go
@@ -6,7 +6,7 @@ import (
 	"testing"
 	"time"

-	"git.t-juice.club/torjus/labmcp/internal/database"
+	"code.t-juice.club/torjus/labmcp/internal/database"
 )

 // TestNixpkgsRevision is the revision from flake.lock used for testing.
--- a/internal/options/indexer.go
+++ b/internal/options/indexer.go
@@ -4,7 +4,7 @@ package options
 import (
 	"context"

-	"git.t-juice.club/torjus/labmcp/internal/database"
+	"code.t-juice.club/torjus/labmcp/internal/database"
 )

 // IndexResult contains the results of an indexing operation.
--- a/internal/packages/indexer.go
+++ b/internal/packages/indexer.go
@@ -12,7 +12,7 @@ import (
 	"strings"
 	"time"

-	"git.t-juice.club/torjus/labmcp/internal/database"
+	"code.t-juice.club/torjus/labmcp/internal/database"
 )

 // revisionPattern validates revision strings to prevent injection attacks.
--- a/nix/git-explorer-module.nix
+++ b/nix/git-explorer-module.nix
@@ -0,0 +1,141 @@
+{ config, lib, pkgs, ... }:
+
+let
+  cfg = config.services.git-explorer;
+
+  mkHttpFlags = httpCfg: lib.concatStringsSep " " ([
+    "--transport http"
+    "--http-address '${httpCfg.address}'"
+    "--http-endpoint '${httpCfg.endpoint}'"
+    "--session-ttl '${httpCfg.sessionTTL}'"
+  ] ++ lib.optionals (httpCfg.allowedOrigins != []) (
+    map (origin: "--allowed-origins '${origin}'") httpCfg.allowedOrigins
+  ) ++ lib.optionals httpCfg.tls.enable [
+    "--tls-cert '${httpCfg.tls.certFile}'"
+    "--tls-key '${httpCfg.tls.keyFile}'"
+  ]);
+in
+{
+  options.services.git-explorer = {
+    enable = lib.mkEnableOption "Git Explorer MCP server";
+
+    package = lib.mkPackageOption pkgs "git-explorer" { };
+
+    repoPath = lib.mkOption {
+      type = lib.types.str;
+      description = "Path to the git repository to serve.";
+    };
+
+    defaultRemote = lib.mkOption {
+      type = lib.types.str;
+      default = "origin";
+      description = "Default remote name for ref resolution.";
+    };
+
+    http = {
+      address = lib.mkOption {
+        type = lib.types.str;
+        default = "127.0.0.1:8085";
+        description = "HTTP listen address for the MCP server.";
+      };
+
+      endpoint = lib.mkOption {
+        type = lib.types.str;
+        default = "/mcp";
+        description = "HTTP endpoint path for MCP requests.";
+      };
+
+      allowedOrigins = lib.mkOption {
+        type = lib.types.listOf lib.types.str;
+        default = [ ];
+        description = "Allowed Origin headers for CORS.";
+      };
+
+      sessionTTL = lib.mkOption {
+        type = lib.types.str;
+        default = "30m";
+        description = "Session TTL for HTTP transport.";
+      };
+
+      tls = {
+        enable = lib.mkEnableOption "TLS for HTTP transport";
+
+        certFile = lib.mkOption {
+          type = lib.types.nullOr lib.types.path;
+          default = null;
+          description = "Path to TLS certificate file.";
+        };
+
+        keyFile = lib.mkOption {
+          type = lib.types.nullOr lib.types.path;
+          default = null;
+          description = "Path to TLS private key file.";
+        };
+      };
+    };
+
+    openFirewall = lib.mkOption {
+      type = lib.types.bool;
+      default = false;
+      description = "Whether to open the firewall for the MCP HTTP server.";
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    assertions = [
+      {
+        assertion = !cfg.http.tls.enable || (cfg.http.tls.certFile != null && cfg.http.tls.keyFile != null);
+        message = "services.git-explorer.http.tls: both certFile and keyFile must be set when TLS is enabled";
+      }
+    ];
+
+    systemd.services.git-explorer = {
+      description = "Git Explorer MCP Server";
+      wantedBy = [ "multi-user.target" ];
+      after = [ "network.target" ];
+
+      environment = {
+        GIT_REPO_PATH = cfg.repoPath;
+        GIT_DEFAULT_REMOTE = cfg.defaultRemote;
+      };
+
+      script = let
+        httpFlags = mkHttpFlags cfg.http;
+      in ''
+        exec ${cfg.package}/bin/git-explorer serve ${httpFlags}
+      '';
+
+      serviceConfig = {
+        Type = "simple";
+        DynamicUser = true;
+        Restart = "on-failure";
+        RestartSec = "5s";
+
+        # Hardening
+        NoNewPrivileges = true;
+        ProtectSystem = "strict";
+        ProtectHome = "read-only";
+        PrivateTmp = true;
+        PrivateDevices = true;
+        ProtectKernelTunables = true;
+        ProtectKernelModules = true;
+        ProtectControlGroups = true;
+        RestrictNamespaces = true;
+        RestrictRealtime = true;
+        RestrictSUIDSGID = true;
+        MemoryDenyWriteExecute = true;
+        LockPersonality = true;
+
+        # Read-only access to repo path
+        ReadOnlyPaths = [ cfg.repoPath ];
+      };
+    };
+
+    networking.firewall = lib.mkIf cfg.openFirewall (let
+      addressParts = lib.splitString ":" cfg.http.address;
+      port = lib.toInt (lib.last addressParts);
+    in {
+      allowedTCPPorts = [ port ];
+    });
+  };
+}
--- a/nix/lab-monitoring-module.nix
+++ b/nix/lab-monitoring-module.nix
@@ -39,6 +39,18 @@ in
      description = "Loki base URL. When set, enables log query tools (query_logs, list_labels, list_label_values).";
    };

+    lokiUsername = lib.mkOption {
+      type = lib.types.nullOr lib.types.str;
+      default = null;
+      description = "Username for Loki basic authentication.";
+    };
+
+    lokiPasswordFile = lib.mkOption {
+      type = lib.types.nullOr lib.types.path;
+      default = null;
+      description = "Path to a file containing the password for Loki basic authentication. Recommended over storing secrets in the Nix store.";
+    };
+
    enableSilences = lib.mkOption {
      type = lib.types.bool;
      default = false;
@@ -112,12 +124,17 @@ in
        ALERTMANAGER_URL = cfg.alertmanagerUrl;
      } // lib.optionalAttrs (cfg.lokiUrl != null) {
        LOKI_URL = cfg.lokiUrl;
+      } // lib.optionalAttrs (cfg.lokiUsername != null) {
+        LOKI_USERNAME = cfg.lokiUsername;
      };

      script = let
        httpFlags = mkHttpFlags cfg.http;
        silenceFlag = lib.optionalString cfg.enableSilences "--enable-silences";
      in ''
+        ${lib.optionalString (cfg.lokiPasswordFile != null) ''
+          export LOKI_PASSWORD="$(< "$CREDENTIALS_DIRECTORY/loki-password")"
+        ''}
        exec ${cfg.package}/bin/lab-monitoring serve ${httpFlags} ${silenceFlag}
      '';

@@ -126,7 +143,9 @@ in
        DynamicUser = true;
        Restart = "on-failure";
        RestartSec = "5s";
-
+      } // lib.optionalAttrs (cfg.lokiPasswordFile != null) {
+        LoadCredential = [ "loki-password:${cfg.lokiPasswordFile}" ];
+      } // {
        # Hardening
        NoNewPrivileges = true;
        ProtectSystem = "strict";
--- a/nix/package.nix
+++ b/nix/package.nix
@@ -7,9 +7,9 @@

 buildGoModule {
  inherit pname src;
-  version = "0.3.0";
+  version = "0.4.0";

-  vendorHash = "sha256-D0KIxQC9ctIAaHBFTvkhBE06uOZwDUcIw8471Ug2doY=";
+  vendorHash = "sha256-XrTtiaQT5br+0ZXz8//rc04GZn/HlQk7l8Nx/+Uil/I=";

  subPackages = [ subPackage ];

@@ -22,7 +22,7 @@ buildGoModule {

  meta = with lib; {
    inherit description mainProgram;
-    homepage = "https://git.t-juice.club/torjus/labmcp";
+    homepage = "https://code.t-juice.club/torjus/labmcp";
    license = licenses.mit;
    maintainers = [ ];
  };
Author	SHA1	Message	Date
Torjus Håkestad	4ae92b4f85	chore: migrate module path from git.t-juice.club to code.t-juice.club Update Go module path and all import references for Gitea to Forgejo host migration. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>	2026-03-09 19:48:25 +01:00
Torjus Håkestad	4276ffbda5	feat: add optional basic auth support for Loki client Some Loki deployments (e.g., behind a reverse proxy or Grafana Cloud) require HTTP Basic Authentication. This adds optional --loki-username and --loki-password flags (and corresponding env vars) to the lab-monitoring server, along with NixOS module options for secure credential management via systemd LoadCredential. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>	2026-02-17 20:32:10 +01:00
Torjus Håkestad	aff058dcc0	chore: update flake.lock Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>	2026-02-13 22:22:08 +01:00
Torjus Håkestad	dcaeb1f517	chore: remove unused gotools and go-tools from devShell Both are redundant: staticcheck is covered by golangci-lint, and gotools (goimports, etc.) is covered by gopls and golangci-lint. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>	2026-02-13 22:20:48 +01:00
Torjus Håkestad	fd40e73f1b	feat: add package indexing to MCP index_revision tool The options server's index_revision now also indexes packages when running under nixpkgs-search, matching the CLI behavior. The packages server gets its own index_revision tool for standalone package indexing. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>	2026-02-13 22:12:08 +01:00
Torjus Håkestad	a0be405b76	Merge pull request 'feat: add git-explorer MCP server for read-only repository access' (#8 ) from feature/git-explorer into master Reviewed-on: #8	2026-02-08 03:30:29 +00:00
Torjus Håkestad	75673974a2	feat: add git-explorer MCP server for read-only repository access Implements a new MCP server that provides read-only access to git repositories using go-git. Designed for deployment verification by comparing deployed flake revisions against source repositories. 9 tools: resolve_ref, get_log, get_commit_info, get_diff_files, get_file_at_commit, is_ancestor, commits_between, list_branches, search_commits. Includes CLI commands, NixOS module, and comprehensive tests. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>	2026-02-08 04:26:38 +01:00
Torjus Håkestad	98bad6c9ba	chore: switch devShell from go_1_24 to default go Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>	2026-02-06 20:07:32 +01:00
Torjus Håkestad	d024f128b5	chore: update flake.lock Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>	2026-02-06 20:02:44 +01:00