Add a plugins command to list installed plugins and check updates

Add a "plugins" command to the platform-neutral mvt command. "plugins
list" shows every installed plugin package with its version, where it was
installed from, how many forensic modules it contributes and which
commands it adds. "plugins check-updates" checks for updates immediately,
without waiting for the automatic check, and prints the command which
upgrades a plugin instead of installing anything.

It lives on mvt only. The packages it lists extend mvt-ios and mvt-android
too, but auditing them is not the job of a command which analyses one
platform, and the two platform CLIs should not carry commands which are
not about an acquisition.

The command is registered as a built-in, before any external command, so
that an installed package cannot replace this audit surface.

README.md

@@ -58,7 +58,7 @@ For alternative installation options and known issues, please refer to the [docu
 
 ## Usage
 
-MVT provides three commands: `mvt-ios` and `mvt-android` analyse acquisitions from devices of that platform, and `mvt` hosts what belongs to neither: `version`, `completion` and `download-iocs` (`version` and `download-iocs` remain available on the platform commands for now). Running `mvt` on its own shows the installed version, update notices and the available commands. [Check out the documentation to learn how to use them!](https://docs.mvt.re/)
+MVT provides three commands: `mvt-ios` and `mvt-android` analyse acquisitions from devices of that platform, and `mvt` hosts what belongs to neither: `version`, `completion`, `plugins` and `download-iocs` (`version` and `download-iocs` remain available on the platform commands for now). Running `mvt` on its own shows the installed version, update notices and the available commands. [Check out the documentation to learn how to use them!](https://docs.mvt.re/)
 
 ### Shell completion
 

docs/development/custom_commands.md

@@ -60,7 +60,8 @@ pipx inject mvt my-mvt-plugin
 ```
 
 When MVT is installed in an active virtual environment, install the plugin with
-`pip` in that environment.
+`pip` in that environment. `mvt plugins list` shows the installed packages and
+the commands they add, see [Managing Plugins](plugins.md).
 
 Command packages that need their own settings, such as an API key, should store
 them in a namespaced [plugin configuration file](plugin_configuration.md)
@@ -69,9 +70,9 @@ rather than in MVT's own `config.yaml`.
 ### Commands on `mvt`
 
 The `mvt` command hosts what belongs to neither platform: `version`,
-`completion` and `download-iocs`. A plugin command which is not about the
-acquisition of one platform, such as one which configures the plugin or
-synchronizes the indicators it uses, belongs there too, in the
+`completion`, `plugins` and `download-iocs`. A plugin command which is not
+about the acquisition of one platform, such as one which configures the plugin
+or synchronizes the indicators it uses, belongs there too, in the
 `mvt.cli_plugins` group:
 
 ```toml

docs/development/index.md

@@ -214,6 +214,9 @@ module came from:
 - When a command runs with an `--output` folder, the `command.log` file
   records one line per module source with the source's version or hash and
   the list of modules loaded from it.
+- `mvt plugins list` lists the installed packages, where each of them
+  was installed from and how many modules it contributes, see
+  [Managing Plugins](plugins.md).
 
 ## Profiling
 

docs/development/plugins.md

@@ -0,0 +1,116 @@
+# Managing Plugins
+
+Plugin packages extend MVT with additional
+[forensic modules](index.md#custom-modules) and
+[CLI commands](custom_commands.md). Because installed packages load
+automatically, `mvt plugins` audits what is installed and checks whether
+updates are available. The command lives on `mvt` only, although the packages
+it lists extend `mvt-ios` and `mvt-android` too.
+
+## List Installed Plugins
+
+```bash
+mvt plugins list
+```
+
+```
+                        Installed MVT plugins
+┏━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━┳━━━━━━━━━━━━━━┳━━━━━━━━━┳━━━━━━━━━━━┓
+┃ Name                ┃ Version ┃ Origin       ┃ Modules ┃ Commands  ┃
+┡━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━╇━━━━━━━━━━━━━━╇━━━━━━━━━╇━━━━━━━━━━━┩
+│ mvt-plugin-example  │ 1.2.0   │ pypi         │       4 │ summarize │
+│ mvt-plugin-research │ 0.1.0   │ git+3f9a1c7d │       2 │ -         │
+│ mvt-plugin-local    │ 0.0.1   │ local        │       1 │ triage    │
+└─────────────────────┴─────────┴──────────────┴─────────┴───────────┘
+```
+
+The origin records where each package was installed from: `pypi` for a package
+installed from a package index, `git+<commit>` for a package installed directly
+from a repository, and `local` for a package installed from a local folder or
+archive rather than from an index, including an editable development install.
+The last two columns show how many forensic modules the package contributes and
+which CLI commands it adds.
+
+A plugin whose modules cannot be imported is listed with `error` in the
+`Modules` column rather than breaking the listing.
+
+## Check for Updates
+
+```bash
+mvt plugins check-updates
+```
+
+```
+Plugin updates available:
+  mvt-plugin-example  1.2.0 → 1.3.0
+    Upgrade with: pip install -U mvt-plugin-example
+
+MVT does not install plugin updates. Run the command above when you decide to
+upgrade.
+```
+
+Packages installed from a package index are compared against the latest release
+published for them. A package which was never published, for example a plugin
+distributed only within an organization, is skipped silently.
+
+!!! note
+
+    Packages shown with the `pypi` origin are compared against
+    [PyPI](https://pypi.org), whichever index they were installed from. A
+    plugin installed from a private index under a name which also exists on
+    PyPI is therefore compared against the unrelated public package of that
+    name. Give plugins published to a private index a name which is not taken
+    on PyPI, and treat an unexpected update suggestion as a reason to check
+    where the package would come from.
+
+!!! warning
+
+    MVT never installs or upgrades a plugin itself, it only prints the command
+    which does. Upgrading a plugin in the middle of an investigation changes
+    the modules producing the results, and a plugin runs as trusted code inside
+    the MVT process, so pulling in a new version is a decision for the analyst
+    to make deliberately and not a side effect of running a check.
+
+## Automatic Update Checks
+
+MVT also reports available plugin updates in the banner printed when a command
+starts:
+
+```
+        MVT - Mobile Verification Toolkit
+
+        https://mvt.re
+        Version: 2026.7.29
+
+        Plugin updates available:
+          mvt-plugin-example  1.2.0 → 1.3.0   (pip install -U mvt-plugin-example)
+```
+
+This check runs at most once every 12 hours. In between checks MVT prints the
+findings of the latest check without contacting anything, so a plugin update
+stays visible without a lookup on every command. The
+`mvt plugins check-updates` command checks immediately, regardless of when the
+last check happened.
+
+The automatic check is skipped when the `--disable-update-check` option is
+used, when `NETWORK_ACCESS_ALLOWED` is disabled in the MVT configuration, and
+when no plugins are installed.
+
+## Plugins Installed From a Repository
+
+A plugin installed with `pip install "mvt-plugin-example @ git+<url>"` is
+checked by asking the remote repository which commit the installed revision
+points at now. MVT runs git and ssh in batch mode, so a repository which needs
+credentials MVT does not already have fails the check instead of prompting for
+them. The check is skipped silently when git is not available, when the
+repository cannot be reached, and when access to it is denied.
+
+How the plugin was installed decides what an update means:
+
+- A plugin installed from a branch is reported as outdated when the branch has
+  moved past the installed commit.
+- A plugin installed from a specific commit or a tag is pinned. It is never
+  reported as outdated, however far the branch it came from moves on.
+
+Pinning a plugin to a commit or a tag is therefore the way to keep the modules
+used across an investigation stable.

mkdocs.yml

@@ -53,4 +53,5 @@ nav:
         - Development Instructions: "development/index.md"
         - Custom CLI Commands: "development/custom_commands.md"
         - Plugin Configuration: "development/plugin_configuration.md"
+        - Managing Plugins: "development/plugins.md"
     - License: "license.md"

src/mvt/cli.py

@@ -11,6 +11,7 @@ from mvt.common.cli_plugins import (
     load_cli_commands_option,
     register_cli_plugins,
 )
+from mvt.common.cmd_plugins import plugins
 from mvt.common.completion import completion
 from mvt.common.help import (
     HELP_MSG_DISABLE_INDICATOR_UPDATE_CHECK,
@@ -84,6 +85,11 @@ def version():
     return
 
 
+# The plugins command is registered as a built-in command, before any external
+# command, so that an installed package can never replace it.
+cli.add_command(plugins)
+
+
 # ==============================================================================
 # Entry point of the mvt console script
 # ==============================================================================

src/mvt/common/cmd_plugins.py

@@ -0,0 +1,205 @@
+# Mobile Verification Toolkit (MVT)
+# Copyright (c) 2021-2026 The MVT Authors.
+# Use of this software is governed by the MVT License 1.1 that can be found at
+#   https://license.mvt.re/1.1/
+
+import importlib.metadata
+import logging
+from typing import Optional
+
+import click
+from rich.console import Console
+from rich.table import Table
+
+from .cli_plugins import (
+    ANDROID_CLI_PLUGIN_GROUP,
+    IOS_CLI_PLUGIN_GROUP,
+    NEUTRAL_CLI_PLUGIN_GROUP,
+)
+from .config import settings
+from .help import (
+    HELP_MSG_PLUGINS,
+    HELP_MSG_PLUGINS_CHECK_UPDATES,
+    HELP_MSG_PLUGINS_LIST,
+)
+from .module import MVTModule
+from .module_loader import MODULES_ENTRY_POINT_GROUP, distribution_direct_url
+from .updates import (
+    SHORT_COMMIT_LENGTH,
+    PluginUpdates,
+    installed_plugin_distributions,
+)
+
+log = logging.getLogger(__name__)
+
+CLI_PLUGIN_GROUPS = (
+    IOS_CLI_PLUGIN_GROUP,
+    ANDROID_CLI_PLUGIN_GROUP,
+    NEUTRAL_CLI_PLUGIN_GROUP,
+)
+CONTEXT_SETTINGS = dict(help_option_names=["-h", "--help"])
+
+
+def _entry_points(group: str) -> list[importlib.metadata.EntryPoint]:
+    try:
+        return list(importlib.metadata.entry_points(group=group))
+    except Exception as exc:
+        log.warning("Unable to discover the entry points in group %s: %s", group, exc)
+        return []
+
+
+def _entry_point_distribution(
+    entry_point: importlib.metadata.EntryPoint,
+) -> Optional[str]:
+    dist = getattr(entry_point, "dist", None)
+    if dist is None:
+        return None
+    try:
+        return dist.name
+    except Exception:
+        return None
+
+
+def _distribution_version(dist: importlib.metadata.Distribution) -> str:
+    try:
+        return dist.version or "unknown"
+    except Exception:
+        return "unknown"
+
+
+def _distribution_origin(dist: importlib.metadata.Distribution) -> str:
+    """Describe where a plugin package was installed from."""
+    direct_url = distribution_direct_url(dist)
+    if direct_url is None:
+        return "pypi"
+
+    vcs_info = direct_url.get("vcs_info")
+    if isinstance(vcs_info, dict):
+        commit = vcs_info.get("commit_id") or ""
+        if commit:
+            return f"git+{commit[:SHORT_COMMIT_LENGTH]}"
+        return "git"
+
+    return "local"
+
+
+def _contributed_modules(
+    entry_points: list[importlib.metadata.EntryPoint], distribution: str
+) -> str:
+    """Count the forensic modules a plugin package contributes.
+
+    Entry points are resolved the way MVT resolves them when it loads
+    modules, but a broken entry point is reported instead of raising: listing
+    the installed plugins must work even when one of them is faulty.
+    """
+    count = 0
+    broken = False
+
+    for entry_point in entry_points:
+        if _entry_point_distribution(entry_point) != distribution:
+            continue
+        try:
+            loaded = entry_point.load()
+            if callable(loaded) and not isinstance(loaded, type):
+                loaded = loaded()
+            count += sum(
+                1
+                for module in loaded
+                if isinstance(module, type) and issubclass(module, MVTModule)
+            )
+        except (Exception, SystemExit) as exc:
+            log.debug(
+                "Unable to load the modules of entry point %s (%s): %s",
+                entry_point.name,
+                entry_point.value,
+                exc,
+            )
+            broken = True
+
+    if broken:
+        return f"{count} (error)" if count else "error"
+
+    return str(count)
+
+
+def _contributed_commands(
+    entry_points: list[importlib.metadata.EntryPoint], distribution: str
+) -> str:
+    names = {
+        entry_point.name
+        for entry_point in entry_points
+        if _entry_point_distribution(entry_point) == distribution
+    }
+
+    return ", ".join(sorted(names)) if names else "-"
+
+
+@click.group("plugins", context_settings=CONTEXT_SETTINGS, help=HELP_MSG_PLUGINS)
+def plugins() -> None:
+    pass
+
+
+@plugins.command("list", context_settings=CONTEXT_SETTINGS, help=HELP_MSG_PLUGINS_LIST)
+def list_plugins() -> None:
+    distributions = installed_plugin_distributions()
+    if not distributions:
+        click.echo("No MVT plugins are installed.")
+        return
+
+    module_entry_points = _entry_points(MODULES_ENTRY_POINT_GROUP)
+    command_entry_points = []
+    for group in CLI_PLUGIN_GROUPS:
+        command_entry_points.extend(_entry_points(group))
+
+    table = Table(title="Installed MVT plugins")
+    table.add_column("Name", style="bold")
+    table.add_column("Version")
+    table.add_column("Origin")
+    table.add_column("Modules", justify="right")
+    table.add_column("Commands")
+
+    for dist in distributions:
+        name = dist.name
+        table.add_row(
+            name,
+            _distribution_version(dist),
+            _distribution_origin(dist),
+            _contributed_modules(module_entry_points, name),
+            _contributed_commands(command_entry_points, name),
+        )
+
+    Console().print(table)
+
+
+@plugins.command(
+    "check-updates",
+    context_settings=CONTEXT_SETTINGS,
+    help=HELP_MSG_PLUGINS_CHECK_UPDATES,
+    short_help="Check the installed plugins for updates",
+)
+def check_plugin_updates() -> None:
+    if not settings.NETWORK_ACCESS_ALLOWED:
+        click.echo(
+            "Network access is disabled, cannot check for plugin updates. "
+            "Enable NETWORK_ACCESS_ALLOWED in the MVT configuration to check."
+        )
+        return
+
+    if not installed_plugin_distributions():
+        click.echo("No MVT plugins are installed.")
+        return
+
+    findings = PluginUpdates().check()
+    if not findings:
+        click.echo("All plugins are up to date.")
+        return
+
+    click.echo("Plugin updates available:")
+    for finding in findings:
+        click.echo(f"  {finding['name']}  {finding['installed']} → {finding['latest']}")
+        click.echo(f"    Upgrade with: {finding['upgrade_command']}")
+
+    click.echo(
+        "\nMVT does not install plugin updates. Run the command above when you "
+        "decide to upgrade."
+    )

src/mvt/common/help.py

@@ -24,6 +24,11 @@ HELP_MSG_DISABLE_INDICATOR_UPDATE_CHECK = "Disable indicators update check"
 HELP_MSG_COMPLETION = (
     "Generate or install shell completion for mvt, mvt-ios and mvt-android"
 )
+HELP_MSG_PLUGINS = "Inspect the installed MVT plugin packages"
+HELP_MSG_PLUGINS_LIST = "List the installed plugins and what they contribute to MVT"
+HELP_MSG_PLUGINS_CHECK_UPDATES = (
+    "Check the installed plugins for updates without installing them"
+)
 
 # IOS Specific
 HELP_MSG_DECRYPT_BACKUP = "Decrypt an encrypted iTunes backup"

src/mvt/common/logo.py

@@ -8,10 +8,125 @@ import logging
 import requests
 from rich import print as rich_print
 
-from .updates import IndicatorsUpdates, MVTUpdates
+from .config import settings
+from .updates import (
+    IndicatorsUpdates,
+    MVTUpdates,
+    PluginUpdates,
+    installed_plugin_distributions,
+)
 from .version import MVT_VERSION
 
 
+def _check_version_updates(log: logging.Logger) -> None:
+    try:
+        mvt_updates = MVTUpdates()
+        latest_version = mvt_updates.check()
+    except (requests.exceptions.ConnectionError, requests.exceptions.Timeout):
+        rich_print(
+            "\t[bold]Note: Could not check for MVT updates.[/bold] "
+            "You may be working offline. Please update MVT regularly."
+        )
+    except Exception as e:
+        log.error("Error encountered when trying to check latest MVT version: %s", e)
+    else:
+        if latest_version:
+            rich_print(
+                f"\t[bold]Version {latest_version} is available! "
+                "Upgrade mvt with `pip3 install -U mvt` or with `pipx upgrade mvt`[/bold]"
+            )
+
+
+def _check_indicator_updates(log: logging.Logger) -> None:
+    ioc_updates = IndicatorsUpdates()
+
+    # Before proceeding, we check if we have downloaded an indicators index.
+    # If not, there's no point in proceeding with the updates check.
+    if ioc_updates.get_latest_update() == 0:
+        rich_print(
+            "\t[bold]You have not yet downloaded any indicators, check "
+            "the `download-iocs` command![/bold]"
+        )
+        return
+
+    # We only perform this check at a fixed frequency, in order to not
+    # overburden the user with too many lookups if the command is being run
+    # multiple times.
+    should_check, hours = ioc_updates.should_check()
+    if not should_check:
+        rich_print(
+            f"\tIndicators updates checked recently, next automatic check "
+            f"in {int(hours)} hours"
+        )
+        return
+
+    try:
+        ioc_to_update = ioc_updates.check()
+    except (requests.exceptions.ConnectionError, requests.exceptions.Timeout):
+        rich_print(
+            "\t[bold]Note: Could not check for indicator updates.[/bold] "
+            "You may be working offline. Please update MVT indicators regularly."
+        )
+    except Exception as e:
+        log.error("Error encountered when trying to check latest MVT indicators: %s", e)
+    else:
+        if ioc_to_update:
+            rich_print(
+                "\t[bold]There are updates to your indicators files! "
+                "Run the `download-iocs` command to update![/bold]"
+            )
+        else:
+            rich_print("\tYour indicators files seem to be up to date.")
+
+
+def _print_plugin_updates(findings: list) -> None:
+    if not findings:
+        return
+
+    rich_print("\t[bold]Plugin updates available:[/bold]")
+    for finding in findings:
+        rich_print(
+            f"\t  {finding['name']}  {finding['installed']} → "
+            f"{finding['latest']}   ({finding['upgrade_command']})"
+        )
+
+
+def _check_plugin_updates(log: logging.Logger) -> None:
+    if not settings.NETWORK_ACCESS_ALLOWED:
+        return
+
+    # This runs on every command, so nothing here, including reading back what
+    # the latest check stored, may ever interrupt MVT.
+    try:
+        distributions = installed_plugin_distributions()
+
+        # There is nothing to check when MVT was not extended with any plugin.
+        if not distributions:
+            return
+
+        plugin_updates = PluginUpdates()
+
+        # We only perform this check at a fixed frequency, in order to not
+        # overburden the user (and the plugin repositories) with too many
+        # lookups. In between checks we print the findings of the latest one,
+        # leaving out those which no longer apply to what is installed.
+        should_check, _ = plugin_updates.should_check()
+        if not should_check:
+            _print_plugin_updates(plugin_updates.current_findings(distributions))
+            return
+
+        findings = plugin_updates.check()
+    except (requests.exceptions.ConnectionError, requests.exceptions.Timeout):
+        rich_print(
+            "\t[bold]Note: Could not check for plugin updates.[/bold] "
+            "You may be working offline. Please update your MVT plugins regularly."
+        )
+    except Exception as e:
+        log.error("Error encountered when trying to check MVT plugin updates: %s", e)
+    else:
+        _print_plugin_updates(findings)
+
+
 def check_updates(
     disable_version_check: bool = False, disable_indicator_check: bool = False
 ) -> None:
@@ -19,68 +134,16 @@ def check_updates(
 
     # First we check for MVT version updates.
     if not disable_version_check:
-        try:
-            mvt_updates = MVTUpdates()
-            latest_version = mvt_updates.check()
-        except (requests.exceptions.ConnectionError, requests.exceptions.Timeout):
-            rich_print(
-                "\t[bold]Note: Could not check for MVT updates.[/bold] "
-                "You may be working offline. Please update MVT regularly."
-            )
-        except Exception as e:
-            log.error(
-                "Error encountered when trying to check latest MVT version: %s", e
-            )
-        else:
-            if latest_version:
-                rich_print(
-                    f"\t[bold]Version {latest_version} is available! "
-                    "Upgrade mvt with `pip3 install -U mvt` or with `pipx upgrade mvt`[/bold]"
-                )
+        _check_version_updates(log)
 
     # Then we check for indicators files updates.
     if not disable_indicator_check:
-        ioc_updates = IndicatorsUpdates()
+        _check_indicator_updates(log)
 
-        # Before proceeding, we check if we have downloaded an indicators index.
-        # If not, there's no point in proceeding with the updates check.
-        if ioc_updates.get_latest_update() == 0:
-            rich_print(
-                "\t[bold]You have not yet downloaded any indicators, check "
-                "the `download-iocs` command![/bold]"
-            )
-            return
-
-        # We only perform this check at a fixed frequency, in order to not
-        # overburden the user with too many lookups if the command is being run
-        # multiple times.
-        should_check, hours = ioc_updates.should_check()
-        if not should_check:
-            rich_print(
-                f"\tIndicators updates checked recently, next automatic check "
-                f"in {int(hours)} hours"
-            )
-            return
-
-        try:
-            ioc_to_update = ioc_updates.check()
-        except (requests.exceptions.ConnectionError, requests.exceptions.Timeout):
-            rich_print(
-                "\t[bold]Note: Could not check for indicator updates.[/bold] "
-                "You may be working offline. Please update MVT indicators regularly."
-            )
-        except Exception as e:
-            log.error(
-                "Error encountered when trying to check latest MVT indicators: %s", e
-            )
-        else:
-            if ioc_to_update:
-                rich_print(
-                    "\t[bold]There are updates to your indicators files! "
-                    "Run the `download-iocs` command to update![/bold]"
-                )
-            else:
-                rich_print("\tYour indicators files seem to be up to date.")
+    # Finally we check for updates to the installed plugin packages. MVT never
+    # installs an update itself, it only reports the command which does.
+    if not disable_version_check:
+        _check_plugin_updates(log)
 
 
 def logo(

src/mvt/common/module_loader.py

@@ -179,21 +179,36 @@ def _module_key(module_class: type[MVTModule]) -> tuple[str, str]:
     return (source, module_class.__qualname__)
 
 
+def distribution_direct_url(dist: importlib.metadata.Distribution) -> Optional[dict]:
+    """Return the PEP 610 direct URL metadata of a distribution, if recorded.
+
+    Packages installed from an index have no direct URL metadata, while
+    packages installed directly from a repository or from a local folder
+    record where they were installed from in ``direct_url.json``.
+    """
+    try:
+        direct_url_text = dist.read_text("direct_url.json")
+        if not direct_url_text:
+            return None
+        direct_url = json.loads(direct_url_text)
+        return direct_url if isinstance(direct_url, dict) else None
+    except Exception:
+        return None
+
+
 def _distribution_commit(dist: importlib.metadata.Distribution) -> Optional[str]:
     """Return the VCS commit a distribution was installed from, if recorded.
 
     Packages installed directly from a repository (``pip install git+...``)
     record the commit in ``direct_url.json`` (PEP 610).
     """
-    try:
-        direct_url_text = dist.read_text("direct_url.json")
-        if not direct_url_text:
-            return None
-        commit = json.loads(direct_url_text).get("vcs_info", {}).get("commit_id")
-        return commit if isinstance(commit, str) else None
-    except Exception:
+    vcs_info = (distribution_direct_url(dist) or {}).get("vcs_info")
+    if not isinstance(vcs_info, dict):
         return None
 
+    commit = vcs_info.get("commit_id")
+    return commit if isinstance(commit, str) else None
+
 
 def _entry_point_origin(entry_point: importlib.metadata.EntryPoint) -> ModuleOrigin:
     name = entry_point.name

src/mvt/common/updates.py

@@ -3,8 +3,13 @@
 # Use of this software is governed by the MVT License 1.1 that can be found at
 #   https://license.mvt.re/1.1/
 
+import importlib.metadata
+import json
 import logging
 import os
+import re
+import shlex
+import subprocess
 from datetime import datetime
 from typing import Optional, Tuple
 
@@ -12,14 +17,35 @@ import requests
 import yaml
 from packaging import version
 
+from .cli_plugins import (
+    ANDROID_CLI_PLUGIN_GROUP,
+    IOS_CLI_PLUGIN_GROUP,
+    NEUTRAL_CLI_PLUGIN_GROUP,
+)
 from .config import settings
 from .indicators import MVT_DATA_FOLDER, MVT_INDICATORS_FOLDER
+from .module_loader import MODULES_ENTRY_POINT_GROUP, distribution_direct_url
 from .version import MVT_VERSION
 
 log = logging.getLogger(__name__)
 
 # In hours.
 INDICATORS_CHECK_FREQUENCY = 12
+PLUGINS_CHECK_FREQUENCY = 12
+
+# The entry-point groups a package can use to extend MVT.
+PLUGIN_ENTRY_POINT_GROUPS = (
+    MODULES_ENTRY_POINT_GROUP,
+    IOS_CLI_PLUGIN_GROUP,
+    ANDROID_CLI_PLUGIN_GROUP,
+    NEUTRAL_CLI_PLUGIN_GROUP,
+)
+SHORT_COMMIT_LENGTH = 8
+# The keys every cached finding has to carry to be printed.
+FINDING_KEYS = ("name", "installed", "latest", "upgrade_command")
+# Options which stop ssh from waiting for an answer nobody is there to give.
+_SSH_BATCH_OPTIONS = ("-o", "BatchMode=yes", "-o", "ConnectTimeout=10")
+_COMMIT_PATTERN = re.compile(r"\A[0-9a-f]{7,40}\Z")
 
 
 class MVTUpdates:
@@ -38,6 +64,395 @@ class MVTUpdates:
         return ""
 
 
+def installed_plugin_distributions() -> list[importlib.metadata.Distribution]:
+    """Return the installed distributions which extend MVT.
+
+    A plugin package is any distribution registering at least one entry point
+    in the module or CLI command groups. Distributions are returned once each,
+    sorted by name. MVT itself is not a plugin and is never returned.
+    """
+    distributions: dict[str, importlib.metadata.Distribution] = {}
+
+    for group in PLUGIN_ENTRY_POINT_GROUPS:
+        try:
+            entry_points = importlib.metadata.entry_points(group=group)
+        except Exception as exc:
+            log.warning(
+                "Unable to discover installed plugin packages in entry-point "
+                "group %s: %s",
+                group,
+                exc,
+            )
+            continue
+
+        for entry_point in entry_points:
+            # Manually constructed entry points have no associated distribution.
+            dist = getattr(entry_point, "dist", None)
+            if dist is None:
+                continue
+            try:
+                name = dist.name
+            except Exception:
+                continue
+            if not name or name == "mvt":
+                continue
+            distributions.setdefault(name, dist)
+
+    return [distributions[name] for name in sorted(distributions)]
+
+
+def _is_usable_finding(finding: object) -> bool:
+    """Check that a cached finding carries everything needed to print it."""
+    if not isinstance(finding, dict):
+        return False
+
+    return all(
+        isinstance(finding.get(key), str) and finding.get(key) for key in FINDING_KEYS
+    )
+
+
+def _installed_revision(
+    dist: importlib.metadata.Distribution, origin: object
+) -> Optional[str]:
+    """Return what a plugin's installed revision is right now.
+
+    This is the value a finding recorded as installed when it was made, so a
+    finding can be compared against the current state of the installation
+    without looking anything up remotely.
+    """
+    try:
+        if origin != "git":
+            return dist.version
+
+        vcs_info = (distribution_direct_url(dist) or {}).get("vcs_info")
+        if not isinstance(vcs_info, dict):
+            return None
+
+        commit = vcs_info.get("commit_id") or ""
+        return commit[:SHORT_COMMIT_LENGTH] or None
+    except Exception as e:
+        log.debug("Failed to read the installed revision of a plugin: %s", e)
+        return None
+
+
+def _batch_mode_ssh_command(ssh_command: str) -> str:
+    """Return an ssh command line which cannot stop to ask a question.
+
+    ssh keeps the first value it is given for a keyword, so the batch mode
+    options are inserted right after the ssh program, ahead of whatever the
+    analyst configured. Their remaining options, such as which key to use,
+    still apply.
+    """
+    try:
+        arguments = shlex.split(ssh_command.strip())
+    except ValueError:
+        arguments = []
+
+    if not arguments:
+        arguments = ["ssh"]
+
+    return shlex.join([arguments[0], *_SSH_BATCH_OPTIONS, *arguments[1:]])
+
+
+def _revision_pins_commit(revision: str, commit: str) -> bool:
+    """Check whether a requested revision pins the installed commit."""
+    candidate = revision.lower()
+    if not _COMMIT_PATTERN.match(candidate):
+        return False
+
+    return commit.lower().startswith(candidate)
+
+
+class PluginUpdates:
+    """Check for updates to the installed MVT plugin packages.
+
+    MVT never installs or upgrades a plugin package itself. It only reports
+    the command which upgrades a plugin, leaving the analyst to decide when to
+    run it.
+    """
+
+    @property
+    def latest_check_path(self) -> str:
+        return os.path.join(MVT_DATA_FOLDER, "latest_plugins_check")
+
+    @property
+    def findings_path(self) -> str:
+        return os.path.join(MVT_DATA_FOLDER, "plugin_updates.json")
+
+    def _create_data_folder(self) -> None:
+        if not os.path.exists(MVT_DATA_FOLDER):
+            os.makedirs(MVT_DATA_FOLDER)
+
+    def get_latest_check(self) -> int:
+        if not os.path.exists(self.latest_check_path):
+            return 0
+
+        # A corrupt or truncated timestamp only means the next check happens
+        # sooner. It must never stop MVT from running.
+        try:
+            with open(self.latest_check_path, "r", encoding="utf-8") as handle:
+                data = handle.read().strip()
+            if data:
+                return int(data)
+        except (OSError, ValueError) as e:
+            log.debug("Failed to read the time of the latest plugin check: %s", e)
+
+        return 0
+
+    def set_latest_check(self) -> None:
+        self._create_data_folder()
+        timestamp = int(datetime.now().timestamp())
+        with open(self.latest_check_path, "w", encoding="utf-8") as handle:
+            handle.write(str(timestamp))
+
+    def get_findings(self) -> list[dict]:
+        """
+        Return the findings of the latest check, without checking again.
+        Returns an empty list if no check was ever performed.
+        """
+        if not os.path.exists(self.findings_path):
+            return []
+
+        try:
+            with open(self.findings_path, "r", encoding="utf-8") as handle:
+                findings = json.load(handle)
+        except Exception as e:
+            log.debug("Failed to read the cached plugin updates: %s", e)
+            return []
+
+        if not isinstance(findings, list):
+            return []
+
+        # Anything which does not look like a finding is dropped rather than
+        # trusted: the cache is only a convenience.
+        return [finding for finding in findings if _is_usable_finding(finding)]
+
+    def current_findings(
+        self, distributions: Optional[list[importlib.metadata.Distribution]] = None
+    ) -> list[dict]:
+        """
+        Return the cached findings which still apply to what is installed.
+        Findings about a plugin which was upgraded or removed since the latest
+        check are dropped, so an update is never reported twice.
+        """
+        if distributions is None:
+            distributions = installed_plugin_distributions()
+
+        installed = {}
+        for dist in distributions:
+            try:
+                installed[dist.name] = dist
+            except Exception:
+                continue
+
+        current = []
+        for finding in self.get_findings():
+            plugin = installed.get(finding["name"])
+            if plugin is None:
+                continue
+            if (
+                _installed_revision(plugin, finding.get("origin"))
+                != finding["installed"]
+            ):
+                continue
+            current.append(finding)
+
+        return current
+
+    def set_findings(self, findings: list[dict]) -> None:
+        self._create_data_folder()
+        with open(self.findings_path, "w", encoding="utf-8") as handle:
+            json.dump(findings, handle)
+
+    def should_check(self) -> Tuple[bool, int]:
+        """
+        Compare time of the latest plugins check with current time.
+        Returns bool and number of hours since the last check.
+        """
+        now = datetime.now()
+        latest_check_ts = self.get_latest_check()
+        latest_check_dt = datetime.fromtimestamp(latest_check_ts)
+
+        diff = now - latest_check_dt
+        diff_hours = divmod(diff.total_seconds(), 3600)[0]
+
+        if diff_hours >= PLUGINS_CHECK_FREQUENCY:
+            return True, 0
+
+        return False, int(PLUGINS_CHECK_FREQUENCY - diff_hours)
+
+    def _check_index_plugin(self, name: str, installed: str) -> Optional[dict]:
+        """Check a plugin installed from a package index for a newer release."""
+        url = f"https://pypi.org/pypi/{name}/json"
+        try:
+            res = requests.get(url, timeout=settings.NETWORK_TIMEOUT)
+        except requests.exceptions.RequestException as e:
+            log.debug("Failed to check for updates to plugin %s: %s", name, e)
+            return None
+
+        # Plugins which were never published to a public index are expected,
+        # and there is nothing to compare their version against.
+        if res.status_code == 404:
+            return None
+
+        if res.status_code != 200:
+            log.debug(
+                "Failed to check for updates to plugin %s (error %d)",
+                name,
+                res.status_code,
+            )
+            return None
+
+        try:
+            latest = res.json().get("info", {}).get("version", "")
+            if not latest or version.parse(latest) <= version.parse(installed):
+                return None
+        except Exception as e:
+            log.debug("Failed to compare the versions of plugin %s: %s", name, e)
+            return None
+
+        return {
+            "name": name,
+            "installed": installed,
+            "latest": latest,
+            "origin": "pypi",
+            # The name comes from package metadata, so the command MVT
+            # suggests is quoted rather than assumed to be shell-safe.
+            "upgrade_command": f"pip install -U {shlex.quote(name)}",
+        }
+
+    def _git_ls_remote(self, url: str, revision: str) -> list[Tuple[str, str]]:
+        """Return the remote references matching a revision, if git allows it."""
+        # Neither value is trusted: they are read from the metadata of an
+        # installed package and must not turn into git options.
+        if url.startswith("-") or revision.startswith("-"):
+            log.debug("Skipping the update check for the invalid repository %s", url)
+            return []
+
+        environment = dict(os.environ)
+        # Never prompt the analyst for repository credentials. git handles its
+        # own prompts, while ssh reads the terminal directly and only batch
+        # mode makes it fail instead of asking.
+        environment["GIT_TERMINAL_PROMPT"] = "0"
+        environment["GIT_SSH_COMMAND"] = _batch_mode_ssh_command(
+            environment.get("GIT_SSH_COMMAND", "")
+        )
+
+        try:
+            process = subprocess.run(
+                ["git", "ls-remote", url, revision],
+                capture_output=True,
+                stdin=subprocess.DEVNULL,
+                text=True,
+                env=environment,
+                timeout=settings.NETWORK_TIMEOUT,
+                check=False,
+            )
+        except FileNotFoundError:
+            log.debug("Could not find git, skipping the update check for %s", url)
+            return []
+        except (subprocess.SubprocessError, OSError) as e:
+            log.debug("Failed to query the repository %s: %s", url, e)
+            return []
+
+        if process.returncode != 0:
+            log.debug(
+                "Failed to query the repository %s (error %d): %s",
+                url,
+                process.returncode,
+                (process.stderr or "").strip(),
+            )
+            return []
+
+        references = []
+        for line in (process.stdout or "").splitlines():
+            commit, _, reference = line.partition("\t")
+            if commit.strip() and reference.strip():
+                references.append((commit.strip(), reference.strip()))
+
+        return references
+
+    def _check_repository_plugin(
+        self, name: str, direct_url: dict, vcs_info: dict
+    ) -> Optional[dict]:
+        """Check a plugin installed from a repository for a newer commit."""
+        url = direct_url.get("url") or ""
+        installed = vcs_info.get("commit_id") or ""
+        revision = vcs_info.get("requested_revision") or ""
+        if not url or not installed:
+            return None
+
+        # A plugin installed from a commit is pinned and never goes out of
+        # date, no matter what the branch it came from does next.
+        if revision and _revision_pins_commit(revision, installed):
+            return None
+
+        latest = ""
+        wanted_reference = f"refs/heads/{revision}" if revision else "HEAD"
+        for commit, reference in self._git_ls_remote(url, revision or "HEAD"):
+            # Tags are pinned installs too.
+            if reference.startswith("refs/tags/"):
+                return None
+            if reference == wanted_reference:
+                latest = commit
+
+        if not latest or latest == installed:
+            return None
+
+        requirement = f"{name} @ git+{url}"
+        if revision:
+            requirement += f"@{revision}"
+
+        return {
+            "name": name,
+            "installed": installed[:SHORT_COMMIT_LENGTH],
+            "latest": latest[:SHORT_COMMIT_LENGTH],
+            "origin": "git",
+            # A repository URL and a branch name can both hold characters a
+            # shell would act on, so the requirement is quoted for the shell
+            # the analyst is going to paste the command into.
+            "upgrade_command": f"pip install -U {shlex.quote(requirement)}",
+        }
+
+    def _check_distribution(
+        self, dist: importlib.metadata.Distribution
+    ) -> Optional[dict]:
+        try:
+            name = dist.name
+            installed = dist.version
+        except Exception as e:
+            log.debug("Failed to read the metadata of an installed plugin: %s", e)
+            return None
+
+        direct_url = distribution_direct_url(dist)
+        if direct_url is None:
+            return self._check_index_plugin(name, installed)
+
+        vcs_info = direct_url.get("vcs_info")
+        if isinstance(vcs_info, dict):
+            return self._check_repository_plugin(name, direct_url, vcs_info)
+
+        # Plugins installed from a local folder, including editable installs,
+        # are maintained by the analyst and have nothing to check against.
+        return None
+
+    def check(self) -> list[dict]:
+        """
+        Check every installed plugin package for an available update.
+        Returns one entry per plugin which can be upgraded.
+        """
+        findings = []
+        for dist in installed_plugin_distributions():
+            finding = self._check_distribution(dist)
+            if finding:
+                findings.append(finding)
+
+        self.set_findings(findings)
+        self.set_latest_check()
+
+        return findings
+
+
 class IndicatorsUpdates:
     def __init__(self) -> None:
         self.github_raw_url = "https://raw.githubusercontent.com/{}/{}/{}/{}"
@@ -180,9 +595,7 @@ class IndicatorsUpdates:
     def _get_remote_file_latest_commit(
         self, owner: str, repo: str, branch: str, path: str
     ) -> int:
-        file_commit_url = (
-            f"https://api.github.com/repos/{owner}/{repo}/commits?path={path}&sha={branch}"
-        )
+        file_commit_url = f"https://api.github.com/repos/{owner}/{repo}/commits?path={path}&sha={branch}"
         try:
             res = requests.get(file_commit_url, timeout=5)
         except requests.exceptions.RequestException as e:

tests/common/test_cmd_plugins.py

@@ -0,0 +1,236 @@
+import json
+from types import SimpleNamespace
+
+import pytest
+from click.testing import CliRunner
+
+from mvt.android.cli import cli as android_cli
+from mvt.cli import cli as mvt_cli
+from mvt.common.cli_plugins import (
+    ANDROID_CLI_PLUGIN_GROUP,
+    IOS_CLI_PLUGIN_GROUP,
+    NEUTRAL_CLI_PLUGIN_GROUP,
+)
+from mvt.common.cmd_plugins import plugins
+from mvt.common.module import MVTModule
+from mvt.common.module_loader import MODULES_ENTRY_POINT_GROUP
+from mvt.common.updates import PluginUpdates
+from mvt.ios.cli import cli as ios_cli
+
+
+class ExampleModule(MVTModule):
+    pass
+
+
+class AnotherModule(MVTModule):
+    pass
+
+
+class FakeDistribution:
+    def __init__(self, name, version="1.0.0", direct_url=None):
+        self.name = name
+        self.version = version
+        self.direct_url = direct_url
+
+    def read_text(self, file_name):
+        if file_name == "direct_url.json" and self.direct_url is not None:
+            return json.dumps(self.direct_url)
+        return None
+
+
+def _entry_point(name, distribution, modules=None, exception=None):
+    def load():
+        if exception is not None:
+            raise exception
+        return modules
+
+    return SimpleNamespace(
+        name=name, value="example_plugin:modules", dist=distribution, load=load
+    )
+
+
+def _run(command, arguments):
+    # Keep rich from wrapping the table while its content is being asserted.
+    return CliRunner().invoke(command, arguments, env={"COLUMNS": "200"})
+
+
+def _table_rows(output):
+    """Return the content of the table rows, without the header and the box."""
+    return [
+        [cell.strip() for cell in line.strip().strip("│").split("│")]
+        for line in output.splitlines()
+        if "│" in line
+    ]
+
+
+def _table_header(output):
+    for line in output.splitlines():
+        if "┃" in line:
+            return [cell.strip() for cell in line.strip().strip("┃").split("┃")]
+    return []
+
+
+def _install(monkeypatch, distributions, entry_points):
+    monkeypatch.setattr(
+        "mvt.common.cmd_plugins.installed_plugin_distributions",
+        lambda: distributions,
+    )
+    monkeypatch.setattr(
+        "mvt.common.cmd_plugins.importlib.metadata.entry_points",
+        lambda *, group: entry_points.get(group, []),
+    )
+
+
+def test_plugins_is_a_builtin_command_of_the_mvt_cli_only():
+    assert mvt_cli.commands["plugins"] is plugins
+    assert "plugins" not in ios_cli.commands
+    assert "plugins" not in android_cli.commands
+
+
+def test_list_shows_what_every_plugin_contributes(monkeypatch):
+    index_plugin = FakeDistribution("example-plugin", version="1.2.0")
+    repository_plugin = FakeDistribution(
+        "repository-plugin",
+        version="0.1.0",
+        direct_url={
+            "url": "https://example.org/plugin.git",
+            "vcs_info": {"vcs": "git", "commit_id": "b" * 40},
+        },
+    )
+    local_plugin = FakeDistribution(
+        "local-plugin",
+        direct_url={"url": "file:///plugins", "dir_info": {"editable": True}},
+    )
+    _install(
+        monkeypatch,
+        [index_plugin, local_plugin, repository_plugin],
+        {
+            MODULES_ENTRY_POINT_GROUP: [
+                _entry_point(
+                    "example", index_plugin, modules=[ExampleModule, AnotherModule]
+                ),
+                _entry_point("local", local_plugin, modules=lambda: [ExampleModule]),
+            ],
+            IOS_CLI_PLUGIN_GROUP: [_entry_point("summarize", repository_plugin)],
+            ANDROID_CLI_PLUGIN_GROUP: [_entry_point("triage", local_plugin)],
+            NEUTRAL_CLI_PLUGIN_GROUP: [_entry_point("report", repository_plugin)],
+        },
+    )
+
+    result = _run(plugins, ["list"])
+
+    assert result.exit_code == 0
+    # Plugins are listed by name, with the modules and the commands each of
+    # them contributes.
+    assert _table_header(result.output) == [
+        "Name",
+        "Version",
+        "Origin",
+        "Modules",
+        "Commands",
+    ]
+    assert _table_rows(result.output) == [
+        ["example-plugin", "1.2.0", "pypi", "2", "-"],
+        ["local-plugin", "1.0.0", "local", "1", "triage"],
+        ["repository-plugin", "0.1.0", "git+bbbbbbbb", "0", "report, summarize"],
+    ]
+
+
+def test_list_reports_a_broken_module_entry_point(monkeypatch):
+    plugin = FakeDistribution("broken-plugin")
+    _install(
+        monkeypatch,
+        [plugin],
+        {
+            MODULES_ENTRY_POINT_GROUP: [
+                _entry_point(
+                    "broken", plugin, exception=ImportError("missing dependency")
+                )
+            ]
+        },
+    )
+
+    result = _run(plugins, ["list"])
+
+    assert result.exit_code == 0
+    assert _table_rows(result.output) == [
+        ["broken-plugin", "1.0.0", "pypi", "error", "-"]
+    ]
+
+
+def test_list_without_plugins(monkeypatch):
+    _install(monkeypatch, [], {})
+
+    result = _run(plugins, ["list"])
+
+    assert result.exit_code == 0
+    assert result.output == "No MVT plugins are installed.\n"
+
+
+def test_check_updates_prints_the_findings_and_ignores_the_throttle(monkeypatch):
+    findings = [
+        {
+            "name": "example-plugin",
+            "installed": "1.0.0",
+            "latest": "1.2.0",
+            "origin": "pypi",
+            "upgrade_command": "pip install -U example-plugin",
+        }
+    ]
+    _install(monkeypatch, [FakeDistribution("example-plugin")], {})
+    monkeypatch.setattr(PluginUpdates, "check", lambda self: findings)
+    monkeypatch.setattr(
+        PluginUpdates,
+        "should_check",
+        lambda self: pytest.fail("an explicit check must not be throttled"),
+    )
+
+    result = _run(plugins, ["check-updates"])
+
+    assert result.exit_code == 0
+    assert "Plugin updates available:" in result.output
+    assert "example-plugin  1.0.0 → 1.2.0" in result.output
+    assert "Upgrade with: pip install -U example-plugin" in result.output
+    assert "MVT does not install plugin updates." in result.output
+
+
+def test_check_updates_without_available_updates(monkeypatch):
+    _install(monkeypatch, [FakeDistribution("example-plugin")], {})
+    monkeypatch.setattr(PluginUpdates, "check", lambda self: [])
+
+    result = _run(plugins, ["check-updates"])
+
+    assert result.exit_code == 0
+    assert "All plugins are up to date." in result.output
+
+
+def test_check_updates_without_plugins(monkeypatch):
+    _install(monkeypatch, [], {})
+    monkeypatch.setattr(
+        PluginUpdates,
+        "check",
+        lambda self: pytest.fail("nothing must be checked without plugins"),
+    )
+
+    result = _run(plugins, ["check-updates"])
+
+    assert result.exit_code == 0
+    assert "No MVT plugins are installed." in result.output
+
+
+def test_check_updates_without_network_access(monkeypatch):
+    monkeypatch.setattr("mvt.common.cmd_plugins.settings.NETWORK_ACCESS_ALLOWED", False)
+    monkeypatch.setattr(
+        "mvt.common.cmd_plugins.installed_plugin_distributions",
+        lambda: pytest.fail("plugins must not be listed without network access"),
+    )
+    monkeypatch.setattr(
+        PluginUpdates,
+        "check",
+        lambda self: pytest.fail("nothing must be checked without network access"),
+    )
+
+    result = _run(plugins, ["check-updates"])
+
+    assert result.exit_code == 0
+    assert "Network access is disabled" in result.output

tests/common/test_plugin_updates.py

@@ -0,0 +1,711 @@
+import json
+import shlex
+from datetime import datetime, timedelta
+from types import SimpleNamespace
+
+import pytest
+
+from mvt.common import logo
+from mvt.common.cli_plugins import (
+    ANDROID_CLI_PLUGIN_GROUP,
+    IOS_CLI_PLUGIN_GROUP,
+    NEUTRAL_CLI_PLUGIN_GROUP,
+)
+from mvt.common.module_loader import MODULES_ENTRY_POINT_GROUP
+from mvt.common.updates import (
+    MVTUpdates,
+    PluginUpdates,
+    installed_plugin_distributions,
+)
+
+
+REPOSITORY_URL = "https://example.org/plugin.git"
+INSTALLED_COMMIT = "a" * 40
+REMOTE_COMMIT = "b" * 40
+
+
+class FakeDistribution:
+    def __init__(self, name, version="1.0.0", direct_url=None):
+        self.name = name
+        self.version = version
+        self.direct_url = direct_url
+
+    def read_text(self, file_name):
+        if file_name == "direct_url.json" and self.direct_url is not None:
+            return json.dumps(self.direct_url)
+        return None
+
+
+class FakeResponse:
+    def __init__(self, status_code=200, payload=None):
+        self.status_code = status_code
+        self.payload = payload or {}
+
+    def json(self):
+        return self.payload
+
+
+def _entry_point(name, distribution, value="plugin:modules"):
+    return SimpleNamespace(name=name, value=value, dist=distribution)
+
+
+def _git_distribution(requested_revision=None, commit=INSTALLED_COMMIT):
+    vcs_info = {"vcs": "git", "commit_id": commit}
+    if requested_revision:
+        vcs_info["requested_revision"] = requested_revision
+
+    return FakeDistribution(
+        "example-plugin",
+        direct_url={"url": REPOSITORY_URL, "vcs_info": vcs_info},
+    )
+
+
+def _fake_git(stdout="", returncode=0, exception=None, calls=None):
+    def run(command, **kwargs):
+        if calls is not None:
+            calls.append((command, kwargs))
+        if exception is not None:
+            raise exception
+        return SimpleNamespace(returncode=returncode, stdout=stdout, stderr="")
+
+    return run
+
+
+@pytest.fixture
+def data_folder(tmp_path, monkeypatch):
+    folder = tmp_path / "mvt-data"
+    monkeypatch.setattr("mvt.common.updates.MVT_DATA_FOLDER", str(folder))
+    return folder
+
+
+@pytest.fixture
+def one_plugin(monkeypatch):
+    def install(distribution):
+        monkeypatch.setattr(
+            "mvt.common.updates.installed_plugin_distributions",
+            lambda: [distribution],
+        )
+        return distribution
+
+    return install
+
+
+def test_installed_plugin_distributions_covers_every_plugin_group(monkeypatch):
+    zeta = FakeDistribution("zeta-plugin")
+    alpha = FakeDistribution("alpha-plugin")
+    neutral = FakeDistribution("neutral-plugin")
+
+    def entry_points(*, group):
+        if group == MODULES_ENTRY_POINT_GROUP:
+            return [_entry_point("zeta", zeta), _entry_point("alpha", alpha)]
+        if group == IOS_CLI_PLUGIN_GROUP:
+            return [_entry_point("zeta-ios", zeta)]
+        if group == ANDROID_CLI_PLUGIN_GROUP:
+            return [_entry_point("alpha-android", alpha)]
+        if group == NEUTRAL_CLI_PLUGIN_GROUP:
+            return [_entry_point("shared", neutral)]
+        return []
+
+    monkeypatch.setattr(
+        "mvt.common.updates.importlib.metadata.entry_points", entry_points
+    )
+
+    distributions = installed_plugin_distributions()
+
+    assert [distribution.name for distribution in distributions] == [
+        "alpha-plugin",
+        "neutral-plugin",
+        "zeta-plugin",
+    ]
+
+
+def test_installed_plugin_distributions_skips_mvt_and_orphan_entry_points(monkeypatch):
+    entry_points = [
+        _entry_point("builtin", FakeDistribution("mvt")),
+        SimpleNamespace(name="orphan", value="plugin:modules", dist=None),
+        _entry_point("plugin", FakeDistribution("example-plugin")),
+    ]
+    monkeypatch.setattr(
+        "mvt.common.updates.importlib.metadata.entry_points",
+        lambda **kwargs: entry_points,
+    )
+
+    distributions = installed_plugin_distributions()
+
+    assert [distribution.name for distribution in distributions] == ["example-plugin"]
+
+
+def test_installed_plugin_distributions_survives_broken_metadata(monkeypatch, caplog):
+    def entry_points(*, group):
+        raise RuntimeError("invalid package metadata")
+
+    monkeypatch.setattr(
+        "mvt.common.updates.importlib.metadata.entry_points", entry_points
+    )
+
+    assert installed_plugin_distributions() == []
+    assert "Unable to discover installed plugin packages" in caplog.text
+
+
+def test_index_plugin_update_is_reported(monkeypatch, data_folder, one_plugin):
+    one_plugin(FakeDistribution("example-plugin", version="1.0.0"))
+    monkeypatch.setattr(
+        "mvt.common.updates.requests.get",
+        lambda url, **kwargs: FakeResponse(payload={"info": {"version": "1.2.0"}}),
+    )
+
+    findings = PluginUpdates().check()
+
+    assert findings == [
+        {
+            "name": "example-plugin",
+            "installed": "1.0.0",
+            "latest": "1.2.0",
+            "origin": "pypi",
+            "upgrade_command": "pip install -U example-plugin",
+        }
+    ]
+
+
+def test_index_plugin_queries_the_package_index_with_the_configured_timeout(
+    monkeypatch, data_folder, one_plugin
+):
+    one_plugin(FakeDistribution("example-plugin"))
+    requests_made = []
+
+    def get(url, **kwargs):
+        requests_made.append((url, kwargs))
+        return FakeResponse(payload={"info": {"version": "1.0.0"}})
+
+    monkeypatch.setattr("mvt.common.updates.requests.get", get)
+    monkeypatch.setattr("mvt.common.updates.settings.NETWORK_TIMEOUT", 3)
+
+    PluginUpdates().check()
+
+    assert requests_made == [
+        ("https://pypi.org/pypi/example-plugin/json", {"timeout": 3})
+    ]
+
+
+def test_up_to_date_index_plugin_is_not_reported(monkeypatch, data_folder, one_plugin):
+    one_plugin(FakeDistribution("example-plugin", version="1.2.0"))
+    monkeypatch.setattr(
+        "mvt.common.updates.requests.get",
+        lambda url, **kwargs: FakeResponse(payload={"info": {"version": "1.2.0"}}),
+    )
+
+    assert PluginUpdates().check() == []
+
+
+def test_unpublished_plugin_is_skipped_silently(monkeypatch, data_folder, one_plugin):
+    one_plugin(FakeDistribution("private-plugin"))
+    monkeypatch.setattr(
+        "mvt.common.updates.requests.get",
+        lambda url, **kwargs: FakeResponse(status_code=404),
+    )
+
+    assert PluginUpdates().check() == []
+
+
+def test_repository_plugin_following_a_branch_is_reported(
+    monkeypatch, data_folder, one_plugin
+):
+    one_plugin(_git_distribution(requested_revision="main"))
+    calls = []
+    monkeypatch.setattr(
+        "mvt.common.updates.subprocess.run",
+        _fake_git(stdout=f"{REMOTE_COMMIT}\trefs/heads/main\n", calls=calls),
+    )
+    monkeypatch.delenv("GIT_SSH_COMMAND", raising=False)
+
+    findings = PluginUpdates().check()
+
+    assert findings == [
+        {
+            "name": "example-plugin",
+            "installed": "aaaaaaaa",
+            "latest": "bbbbbbbb",
+            "origin": "git",
+            "upgrade_command": (
+                f"pip install -U 'example-plugin @ git+{REPOSITORY_URL}@main'"
+            ),
+        }
+    ]
+    command, options = calls[0]
+    assert command == ["git", "ls-remote", REPOSITORY_URL, "main"]
+    assert options["env"]["GIT_TERMINAL_PROMPT"] == "0"
+    # ssh asks the terminal for a passphrase or a host key unless it is told
+    # not to, which git itself cannot prevent.
+    assert options["env"]["GIT_SSH_COMMAND"] == (
+        "ssh -o BatchMode=yes -o ConnectTimeout=10"
+    )
+
+
+def test_batch_mode_options_come_before_the_configured_ssh_options(
+    monkeypatch, data_folder, one_plugin
+):
+    one_plugin(_git_distribution(requested_revision="main"))
+    calls = []
+    monkeypatch.setattr(
+        "mvt.common.updates.subprocess.run",
+        _fake_git(stdout=f"{REMOTE_COMMIT}\trefs/heads/main\n", calls=calls),
+    )
+    monkeypatch.setenv("GIT_SSH_COMMAND", "ssh -o BatchMode=no -i /home/analyst/key")
+
+    PluginUpdates().check()
+
+    # ssh uses the first value it is given for a keyword, so an analyst asking
+    # for prompts cannot bring them back, while their other options still
+    # apply.
+    assert calls[0][1]["env"]["GIT_SSH_COMMAND"] == (
+        "ssh -o BatchMode=yes -o ConnectTimeout=10 -o BatchMode=no -i /home/analyst/key"
+    )
+
+
+def test_repository_plugin_without_a_revision_follows_the_default_branch(
+    monkeypatch, data_folder, one_plugin
+):
+    one_plugin(_git_distribution())
+    calls = []
+    monkeypatch.setattr(
+        "mvt.common.updates.subprocess.run",
+        _fake_git(stdout=f"{REMOTE_COMMIT}\tHEAD\n", calls=calls),
+    )
+
+    findings = PluginUpdates().check()
+
+    assert calls[0][0] == ["git", "ls-remote", REPOSITORY_URL, "HEAD"]
+    assert findings[0]["upgrade_command"] == (
+        f"pip install -U 'example-plugin @ git+{REPOSITORY_URL}'"
+    )
+
+
+def test_hostile_revision_cannot_inject_into_the_upgrade_command(
+    monkeypatch, data_folder, one_plugin
+):
+    revision = "main$(id)`id`;id"
+    one_plugin(_git_distribution(requested_revision=revision))
+    monkeypatch.setattr(
+        "mvt.common.updates.subprocess.run",
+        _fake_git(stdout=f"{REMOTE_COMMIT}\trefs/heads/{revision}\n"),
+    )
+
+    upgrade_command = PluginUpdates().check()[0]["upgrade_command"]
+
+    # Single quotes are the only quoting a shell does not expand anything in.
+    assert upgrade_command == (
+        f"pip install -U 'example-plugin @ git+{REPOSITORY_URL}@{revision}'"
+    )
+    assert shlex.split(upgrade_command) == [
+        "pip",
+        "install",
+        "-U",
+        f"example-plugin @ git+{REPOSITORY_URL}@{revision}",
+    ]
+
+
+def test_repository_plugin_with_an_option_like_url_is_skipped(
+    monkeypatch, data_folder, one_plugin
+):
+    one_plugin(
+        FakeDistribution(
+            "example-plugin",
+            direct_url={
+                "url": "--upload-pack=touch /tmp/mvt",
+                "vcs_info": {"vcs": "git", "commit_id": INSTALLED_COMMIT},
+            },
+        )
+    )
+    calls = []
+    monkeypatch.setattr("mvt.common.updates.subprocess.run", _fake_git(calls=calls))
+
+    assert PluginUpdates().check() == []
+    assert calls == []
+
+
+def test_repository_plugin_with_an_option_like_revision_is_skipped(
+    monkeypatch, data_folder, one_plugin
+):
+    one_plugin(_git_distribution(requested_revision="--upload-pack=touch /tmp/mvt"))
+    calls = []
+    monkeypatch.setattr("mvt.common.updates.subprocess.run", _fake_git(calls=calls))
+
+    assert PluginUpdates().check() == []
+    assert calls == []
+
+
+def test_repository_plugin_at_the_latest_commit_is_not_reported(
+    monkeypatch, data_folder, one_plugin
+):
+    one_plugin(_git_distribution(requested_revision="main"))
+    monkeypatch.setattr(
+        "mvt.common.updates.subprocess.run",
+        _fake_git(stdout=f"{INSTALLED_COMMIT}\trefs/heads/main\n"),
+    )
+
+    assert PluginUpdates().check() == []
+
+
+def test_commit_pinned_repository_plugin_is_never_outdated(
+    monkeypatch, data_folder, one_plugin
+):
+    one_plugin(_git_distribution(requested_revision=INSTALLED_COMMIT))
+    calls = []
+    monkeypatch.setattr("mvt.common.updates.subprocess.run", _fake_git(calls=calls))
+
+    assert PluginUpdates().check() == []
+    assert calls == []
+
+
+def test_short_commit_pinned_repository_plugin_is_never_outdated(
+    monkeypatch, data_folder, one_plugin
+):
+    one_plugin(_git_distribution(requested_revision=INSTALLED_COMMIT[:10]))
+    calls = []
+    monkeypatch.setattr("mvt.common.updates.subprocess.run", _fake_git(calls=calls))
+
+    assert PluginUpdates().check() == []
+    assert calls == []
+
+
+def test_tag_pinned_repository_plugin_is_never_outdated(
+    monkeypatch, data_folder, one_plugin
+):
+    one_plugin(_git_distribution(requested_revision="v1.0.0"))
+    monkeypatch.setattr(
+        "mvt.common.updates.subprocess.run",
+        _fake_git(stdout=f"{REMOTE_COMMIT}\trefs/tags/v1.0.0\n"),
+    )
+
+    assert PluginUpdates().check() == []
+
+
+def test_repository_plugin_is_skipped_without_git(monkeypatch, data_folder, one_plugin):
+    one_plugin(_git_distribution(requested_revision="main"))
+    monkeypatch.setattr(
+        "mvt.common.updates.subprocess.run",
+        _fake_git(exception=FileNotFoundError("git")),
+    )
+
+    assert PluginUpdates().check() == []
+
+
+def test_repository_plugin_is_skipped_when_git_fails(
+    monkeypatch, data_folder, one_plugin
+):
+    one_plugin(_git_distribution(requested_revision="main"))
+    monkeypatch.setattr(
+        "mvt.common.updates.subprocess.run",
+        _fake_git(stdout="", returncode=128),
+    )
+
+    assert PluginUpdates().check() == []
+
+
+def test_local_plugin_install_is_skipped(monkeypatch, data_folder, one_plugin):
+    one_plugin(
+        FakeDistribution(
+            "example-plugin",
+            direct_url={
+                "url": "file:///home/analyst/example-plugin",
+                "dir_info": {"editable": True},
+            },
+        )
+    )
+
+    def fail(*args, **kwargs):
+        raise AssertionError("a local plugin install must not be checked")
+
+    monkeypatch.setattr("mvt.common.updates.requests.get", fail)
+    monkeypatch.setattr("mvt.common.updates.subprocess.run", fail)
+
+    assert PluginUpdates().check() == []
+
+
+def test_check_stores_the_findings_and_the_check_timestamp(
+    monkeypatch, data_folder, one_plugin
+):
+    one_plugin(FakeDistribution("example-plugin", version="1.0.0"))
+    monkeypatch.setattr(
+        "mvt.common.updates.requests.get",
+        lambda url, **kwargs: FakeResponse(payload={"info": {"version": "1.2.0"}}),
+    )
+    plugin_updates = PluginUpdates()
+
+    findings = plugin_updates.check()
+
+    assert json.loads((data_folder / "plugin_updates.json").read_text()) == findings
+    assert (data_folder / "latest_plugins_check").read_text().isdigit()
+    assert PluginUpdates().get_findings() == findings
+
+
+def test_findings_are_empty_before_the_first_check(data_folder):
+    assert PluginUpdates().get_findings() == []
+
+
+def test_malformed_cached_findings_are_dropped(data_folder):
+    plugin_updates = PluginUpdates()
+    usable = {
+        "name": "example-plugin",
+        "installed": "1.0.0",
+        "latest": "1.2.0",
+        "origin": "pypi",
+        "upgrade_command": "pip install -U example-plugin",
+    }
+    data_folder.mkdir(parents=True, exist_ok=True)
+    (data_folder / "plugin_updates.json").write_text(
+        json.dumps(
+            [
+                {"oops": 1},
+                "not a finding",
+                {"name": "half-plugin", "installed": "1.0.0"},
+                {**usable, "latest": None},
+                usable,
+            ]
+        ),
+        encoding="utf-8",
+    )
+
+    assert plugin_updates.get_findings() == [usable]
+
+
+def test_corrupt_cached_findings_are_ignored(data_folder):
+    data_folder.mkdir(parents=True, exist_ok=True)
+    (data_folder / "plugin_updates.json").write_text("{ not json", encoding="utf-8")
+
+    assert PluginUpdates().get_findings() == []
+
+
+def test_cached_findings_of_upgraded_and_removed_plugins_are_dropped(
+    monkeypatch, data_folder
+):
+    findings = [
+        {
+            "name": "upgraded-plugin",
+            "installed": "1.0.0",
+            "latest": "1.2.0",
+            "origin": "pypi",
+            "upgrade_command": "pip install -U upgraded-plugin",
+        },
+        {
+            "name": "removed-plugin",
+            "installed": "1.0.0",
+            "latest": "1.2.0",
+            "origin": "pypi",
+            "upgrade_command": "pip install -U removed-plugin",
+        },
+        {
+            "name": "example-plugin",
+            "installed": "1.0.0",
+            "latest": "1.2.0",
+            "origin": "pypi",
+            "upgrade_command": "pip install -U example-plugin",
+        },
+    ]
+    plugin_updates = PluginUpdates()
+    plugin_updates.set_findings(findings)
+    monkeypatch.setattr(
+        "mvt.common.updates.installed_plugin_distributions",
+        lambda: [
+            # The analyst upgraded this plugin since the latest check.
+            FakeDistribution("upgraded-plugin", version="1.2.0"),
+            FakeDistribution("example-plugin", version="1.0.0"),
+        ],
+    )
+
+    assert plugin_updates.current_findings() == [findings[2]]
+
+
+def test_cached_findings_of_updated_repository_plugins_are_dropped(data_folder):
+    findings = [
+        {
+            "name": "example-plugin",
+            "installed": "aaaaaaaa",
+            "latest": "bbbbbbbb",
+            "origin": "git",
+            "upgrade_command": "pip install -U example-plugin",
+        }
+    ]
+    plugin_updates = PluginUpdates()
+    plugin_updates.set_findings(findings)
+
+    assert plugin_updates.current_findings([_git_distribution()]) == findings
+    assert (
+        plugin_updates.current_findings([_git_distribution(commit=REMOTE_COMMIT)]) == []
+    )
+
+
+def test_corrupt_check_timestamp_does_not_raise(data_folder):
+    plugin_updates = PluginUpdates()
+    data_folder.mkdir(parents=True, exist_ok=True)
+    (data_folder / "latest_plugins_check").write_text("truncated", encoding="utf-8")
+
+    assert plugin_updates.get_latest_check() == 0
+    assert plugin_updates.should_check() == (True, 0)
+
+
+def test_should_check_is_throttled_for_twelve_hours(data_folder):
+    plugin_updates = PluginUpdates()
+    plugin_updates.set_findings([])
+
+    recent = datetime.now() - timedelta(hours=4)
+    with open(plugin_updates.latest_check_path, "w", encoding="utf-8") as handle:
+        handle.write(str(int(recent.timestamp())))
+
+    should_check, hours = plugin_updates.should_check()
+    assert not should_check
+    assert hours == 8
+
+    old = datetime.now() - timedelta(hours=13)
+    with open(plugin_updates.latest_check_path, "w", encoding="utf-8") as handle:
+        handle.write(str(int(old.timestamp())))
+
+    assert plugin_updates.should_check() == (True, 0)
+
+
+def test_should_check_without_a_previous_check(data_folder):
+    assert PluginUpdates().should_check() == (True, 0)
+
+
+@pytest.fixture
+def no_version_check(monkeypatch):
+    monkeypatch.setattr(MVTUpdates, "check", lambda self: "")
+    # Keep rich from wrapping the plugin lines while they are being asserted.
+    monkeypatch.setenv("COLUMNS", "200")
+
+
+@pytest.fixture
+def throttled_cache(monkeypatch, data_folder):
+    """Fill the findings cache and put the check inside its throttle window."""
+
+    def fill(findings, distributions):
+        PluginUpdates().set_findings(findings)
+        monkeypatch.setattr(
+            logo, "installed_plugin_distributions", lambda: distributions
+        )
+        monkeypatch.setattr(PluginUpdates, "should_check", lambda self: (False, 8))
+        monkeypatch.setattr(
+            PluginUpdates,
+            "check",
+            lambda self: pytest.fail("the check must be throttled"),
+        )
+
+    return fill
+
+
+def test_logo_prints_the_cached_plugin_updates(
+    capsys, no_version_check, throttled_cache
+):
+    throttled_cache(
+        [
+            {
+                "name": "example-plugin",
+                "installed": "1.0.0",
+                "latest": "1.2.0",
+                "origin": "pypi",
+                "upgrade_command": "pip install -U example-plugin",
+            }
+        ],
+        [FakeDistribution("example-plugin", version="1.0.0")],
+    )
+
+    logo.check_updates(disable_indicator_check=True)
+
+    output = capsys.readouterr().out
+    assert "Plugin updates available:" in output
+    assert "example-plugin  1.0.0 → 1.2.0   (pip install -U example-plugin)" in output
+
+
+def test_logo_does_not_print_a_cached_update_of_an_upgraded_plugin(
+    capsys, no_version_check, throttled_cache
+):
+    throttled_cache(
+        [
+            {
+                "name": "example-plugin",
+                "installed": "1.0.0",
+                "latest": "1.2.0",
+                "origin": "pypi",
+                "upgrade_command": "pip install -U example-plugin",
+            }
+        ],
+        # The analyst already upgraded the plugin the cached finding is about.
+        [FakeDistribution("example-plugin", version="1.2.0")],
+    )
+
+    logo.check_updates(disable_indicator_check=True)
+
+    assert "Plugin updates" not in capsys.readouterr().out
+
+
+def test_logo_prints_nothing_when_throttled_without_findings(
+    capsys, no_version_check, throttled_cache
+):
+    throttled_cache([], [FakeDistribution("example-plugin")])
+
+    logo.check_updates(disable_indicator_check=True)
+
+    assert "Plugin updates" not in capsys.readouterr().out
+
+
+def test_logo_survives_a_corrupt_plugin_cache(
+    monkeypatch, capsys, data_folder, no_version_check
+):
+    data_folder.mkdir(parents=True, exist_ok=True)
+    (data_folder / "plugin_updates.json").write_text(
+        json.dumps([{"oops": 1}]), encoding="utf-8"
+    )
+    monkeypatch.setattr(
+        logo,
+        "installed_plugin_distributions",
+        lambda: [FakeDistribution("example-plugin")],
+    )
+    monkeypatch.setattr(PluginUpdates, "should_check", lambda self: (False, 8))
+
+    logo.check_updates(disable_indicator_check=True)
+
+    assert "Plugin updates" not in capsys.readouterr().out
+
+
+def test_logo_skips_the_plugin_check_without_plugins(
+    monkeypatch, capsys, no_version_check
+):
+    monkeypatch.setattr(logo, "installed_plugin_distributions", list)
+    monkeypatch.setattr(
+        PluginUpdates,
+        "should_check",
+        lambda self: pytest.fail("plugins must not be checked without plugins"),
+    )
+
+    logo.check_updates(disable_indicator_check=True)
+
+    assert "Plugin updates" not in capsys.readouterr().out
+
+
+def test_logo_skips_the_plugin_check_without_network_access(
+    monkeypatch, capsys, no_version_check
+):
+    monkeypatch.setattr("mvt.common.logo.settings.NETWORK_ACCESS_ALLOWED", False)
+    monkeypatch.setattr(
+        logo,
+        "installed_plugin_distributions",
+        lambda: pytest.fail("plugins must not be listed without network access"),
+    )
+
+    logo.check_updates(disable_indicator_check=True)
+
+    assert "Plugin updates" not in capsys.readouterr().out
+
+
+def test_logo_skips_the_plugin_check_when_update_checks_are_disabled(
+    monkeypatch, capsys
+):
+    monkeypatch.setattr(
+        logo,
+        "installed_plugin_distributions",
+        lambda: pytest.fail("plugins must not be checked with --disable-update-check"),
+    )
+
+    logo.check_updates(disable_version_check=True, disable_indicator_check=True)
+
+    assert capsys.readouterr().out == ""