stack-viewer

A side pane that maps every component your Claude Code session runs and where each one is installed from. The sidebar lists the component types. Pick one and the pane draws its scopes as a tree, in precedence order, with what is installed in each scope and whether it is active, shadowed by a higher scope, or off.

╭──────────────────────────────────────────────────────────────────────────────╮
│ ◆ Session stack  Claude Code 2.1.306                                         │
│ ~/work/app  ● 159 active  ⊘ 7 shadowed  ○ 0 off                              │
╰──────────────────────────────────────────────────────────────────────────────╯

 COMPONENTS                 ✦ Skills   22 active · 1 shadowed
▌✦ 1: Skills         22 ⊘1  Enterprise › User › Project on a name clash · plugin
 ◎ 2: Subagents       4 ⊘1  skills are namespaced, both load
 ❯ 3: Commands       99 ⊘1
 ↯ 4: Hooks           7     ██████████████████████████████████████████████████
 ⇄ 5: MCP servers     3 ⊘2  ■ User 2   ■ Project 2   ■ Plugin 3   ■ Built-in 16
 ◈ 6: Plugins & mods  3
 ⚙ 7: Settings       11 ⊘2  ·  1  Enterprise          —    managed settings dir
 ¶ 8: Memory          2     ▾  2  User                2    ~/.claude/skills
 ✎ 9: Output styles   8     │ ├─ ● deploy
                            │ └─ ● pdf-tools
 ● active                   ▾  3  Project             2 ⊘1 .claude/skills
 ⊘ shadowed                 │ ├─ ⊘ deploy     shadowed by User
 ○ off                      │ └─ ● release-notes
 ≈ scope read off files     ▾  4  Plugin              3    <plugin>/skills · …
  1  highest precedence     │ ├─ ● hello-mod:greet
                            │ ├─ ● team-tools:changelog
                            │ └─ ● team-tools:pr
                            ·  5  claude.ai account   —    enabled on claude.ai
                            ·  6  MCP server          —    skills an MCP server…
                            ▸  7  Built-in           16    ship with Claude Code

[ refresh ] [ fold all ] [ close ]

Run /stack to open it, /stack refresh (or running /stack again) to read the stack again, /stack close to close it.

What it shows

Each type lists every scope it can be installed at, empty ones included, so you can see where a component could live as well as where it does. The badge number is the scope's precedence: 1 wins over 2 when two components share a name.

A shadowed component is struck through with the scope that wins over it (shadowed by User, overridden by Local). An off component is installed but not loaded: a skill with a broken frontmatter, a hook under allowManagedHooksOnly, a plugin disabled in a higher scope, an MCP server that did not connect.

Where the data comes from

What is loaded comes from the engine, so it is what the session really runs:

• skills, custom subagents, MCP tools and memory files from the /context breakdown ($.session.usage({ breakdown }))
• slash commands from $.command.list()
• each settings source as loaded from $.settings.read({ source }) (hooks, enabledPlugins, outputStyle, every key)
• the MCP server's config scope from each MCP tool call (mcp_server.source), once the server has been called
• the output style the engine sends, from prompt.compose

Where a file sits comes from reading the folders each type installs to: ~/.claude (or $CLAUDE_CONFIG_DIR), the project's .claude/, the managed settings directory, ~/.claude/plugins/installed_plugins.json, .claude.json and .mcp.json. That is how the pane finds what the engine does not list, a project skill shadowed by a user one for example. A scope known only from files, never confirmed by the engine, is marked ≈: a plugin loaded with --plugin-dir, an MCP server not in any config file, a mod in a project skills dir (it loads once the folder is trusted).

From MCP config files the mod keeps server names only, never their env, headers or arguments. Settings values are shown in one short line: env shows variable names, never values, and a settings key whose name looks sensitive (key, token, secret, auth, helper, uuid, org…) shows •••. Hook commands and URLs are shown with bearer tokens, secret-looking parameters and flags (token=, --api-key=, sig=…) and long opaque strings masked as •••. Nothing is written to disk or kept between sessions.

The mods API does not list the built-in subagents (Explore, Plan, general-purpose…), so their scope shows a note instead of items. Nested .claude/ folders between the working directory and the repository root are not scanned; the engine still reports what loads from them.

Controls

• Click a type in the sidebar, or focus the pane (ctrl+x tab) and press 1–9.
• Click a scope to fold or unfold it. Long built-in lists start folded.
• r or refresh reads the stack again, after you install something mid-session.

Where it draws

In the fullscreen layout the engine docks the pane beside the transcript (turn it on with /tui fullscreen, at least 110 columns). On the classic layout it sits above the prompt. Under 72 columns the sidebar becomes a row of chips above the tree. In Claude Desktop the pane draws in the session's side panel, and every padded cell uses non-breaking spaces so the columns keep their width.

Options

Set them in user or managed settings under pluginConfigs["stack-viewer@skills-dir"].options ("stack-viewer" when loaded with --plugin-dir):

Install

npx claude-code-templates@latest --mod ui/stack-viewer

The CLI writes the plugin to .claude/skills/stack-viewer/, which Claude Code loads as stack-viewer@skills-dir once the project is trusted. To load it everywhere, copy that folder to ~/.claude/skills/.

Needs Claude Code 2.1.287 or later. It only observes: every hook passes its event on unchanged.