claude-desktop-debian/docs/testing/cases/extensibility.md

Extensibility — Plugins, MCP, Hooks, Memory

Tests covering the Anthropic & Partners plugin install flow, the plugin browser, MCP server config, hooks, CLAUDE.md memory loading, and per-user storage of plugins/worktrees. See ../matrix.md for status.

T11 — Plugin install (Anthropic & Partners)

Severity: Smoke Surface: Plugin browser → install flow Applies to: All rows Issues: docs/learnings/plugin-install.md

Steps:

1. In a Code-tab session, click + → Plugins → Add plugin.
2. Find an Anthropic & Partners plugin. Click Install.
3. Verify it lands in Manage plugins and its skills appear in the slash menu.
4. Re-install the same plugin to verify idempotence.

Expected: Install completes end-to-end: gate logic accepts, backend endpoint responds, plugin appears in the plugin list. Re-install is idempotent.

Diagnostics on failure: DevTools network panel during install, launcher log, ~/.claude/plugins/ content, the gate-logic code path (see learnings doc).

References: docs/learnings/plugin-install.md, Install plugins

Code anchors: build-reference/app-extracted/.vite/build/index.js:507181 (installPlugin IPC + gate, with pluginSource === "remote" branch and CLI fallback); :507193 log [CustomPlugins] installPlugin: attempting remote API install; :465816 dx() returns ~/.claude/plugins; :465822 installed_plugins.json (idempotency record).

Inventory anchor: …customize.main.navigation.button-by-name.add-plugin (role button, label Add plugin); sibling …button-by-name.browse-plugins (label Browse plugins). Both are persistent in the Customize panel — anchors the entry-point click chain.

T33 — Plugin browser

Severity: Should Surface: Plugin browser UI Applies to: All rows Issues: —

Steps:

1. Click + → Plugins → Add plugin.
2. Confirm entries from the official Anthropic marketplace appear.
3. Install a non-Anthropic plugin end-to-end.
4. Verify it shows in Manage plugins and contributes its skills to the slash menu.

Expected: Plugin browser opens, shows the marketplace, install completes. Installed plugins appear under Manage plugins and contribute to the slash menu.

Diagnostics on failure: Screenshot of plugin browser, network captures, launcher log, ~/.claude/plugins/ listing.

References: Install plugins

Code anchors: build-reference/app-extracted/.vite/build/index.js:71392 (CustomPlugins.listMarketplaces IPC); :71534 (listAvailablePlugins IPC); :507176 (listMarketplaces main-process handler); :496236 deep-link route plugins/new opens the browser surface.

Inventory anchor: …customize.main.navigation.button-by-name.browse-plugins (role button, label Browse plugins); sibling …link-by-name.connectors (role link, label Connectors). The browser surface itself (marketplace listings, install button) appears under a child dialog not captured at idle — re-capture with the dialog open to anchor those.

T35 — MCP server config picked up

Severity: Critical Surface: MCP / Code tab Applies to: All rows Issues: —

Steps:

1. Add an MCP server to ~/.claude.json or <project>/.mcp.json.
2. Open a Code-tab session against the project.
3. Type / in the prompt — verify MCP-provided tools appear in the slash menu (or invoke one directly).
4. Separately, confirm claude_desktop_config.json (Chat-tab MCP) is not picked up by Code tab.

Expected: MCP servers in ~/.claude.json or .mcp.json start when a Code session opens. Tools appear in the slash menu, calls succeed end-to-end. claude_desktop_config.json is separate per upstream docs.

Diagnostics on failure: Server stderr (MCP servers log to stderr), ~/.claude.json and .mcp.json content, launcher log, DevTools console for MCP wire errors.

References: MCP servers: desktop chat app vs Claude Code, docs/learnings/plugin-install.md

Code anchors: build-reference/app-extracted/.vite/build/index.js:215418 (Code-tab loads <project>/.mcp.json per scanned dir); :176766 reads ~/.claude.json; :489098 Code-session passes settingSources: ["user", "project", "local"] to the agent SDK; :130821 claude_desktop_config.json is the chat-tab path constant (separate userData dir at :130829 kee()), confirming the two trees do not overlap.

T36 — Hooks fire

Severity: Critical Surface: Hooks runtime Applies to: All rows Issues: —

Steps:

1. Add a SessionStart hook in ~/.claude/settings.json that writes a marker file.
2. Open a new Code-tab session.
3. Confirm the marker file exists.
4. Repeat with PreToolUse / PostToolUse hooks. Switch transcript view to Verbose to see the hook output.

Expected: Hooks defined in ~/.claude/settings.json execute at the documented points. Hook output is visible in Verbose transcript mode. A failing hook surfaces a clear error rather than silently breaking the session.

Diagnostics on failure: Hook script stderr, marker file presence, launcher log, settings file content, Verbose transcript output.

References: Shared configuration

Code anchors: build-reference/app-extracted/.vite/build/index.js:489098 Code-session sets settingSources: ["user", "project", "local"] (agent SDK reads ~/.claude/settings.json hooks from this); :455717 built-in PreToolUse hooks registry the runtime extends; :455819 UserPromptSubmit; :465680 PostToolUse; :465754 Stop; :493411 runtime emits hook_started / hook_progress / hook_response for SessionStart (Verbose transcript path).

T37 — CLAUDE.md memory loads

Severity: Critical Surface: Memory / Code tab session prompt Applies to: All rows Issues: —

Steps:

1. Confirm a project CLAUDE.md exists at the working folder.
2. Confirm ~/.claude/CLAUDE.md exists with at least one identifying token.
3. Open a Code-tab session against the project.
4. Ask Claude "what's in your CLAUDE.md" — verify the response matches on-disk content.
5. Edit CLAUDE.md. Start a new session — verify the new content is loaded.

Expected: Project CLAUDE.md and CLAUDE.local.md at the working folder, plus ~/.claude/CLAUDE.md, are loaded into the session's system prompt. Updates after edit on the next session start.

Diagnostics on failure: cat CLAUDE.md and cat ~/.claude/CLAUDE.md outputs, launcher log, system-prompt dump if accessible (Verbose transcript may show it).

References: Shared configuration

Code anchors: build-reference/app-extracted/.vite/build/index.js:259691 working-dir scan reads CLAUDE.md and .claude/CLAUDE.md; :455188 global account memory zhA(accountId, orgId) is copied to the per-session .claude/CLAUDE.md at session start ([GlobalMemory] Copied CLAUDE.md); :283107 cE() resolves CLAUDE_CONFIG_DIR or ~/.claude, the dir whose CLAUDE.md the agent SDK loads via settingSources: ["user", ...] (see T36 anchor at :489098).

S27 — Plugins install per-user, not into system paths

Severity: Should Surface: Plugin storage Applies to: All rows Issues: —

Steps:

1. As a non-root user, install a plugin via the desktop plugin browser.
2. Inspect ~/.claude/plugins/ for the install.
3. Verify nothing was written under /usr or other system-managed trees (find /usr -newer /tmp/marker -name '*claude*' 2>/dev/null after touch /tmp/marker; install plugin).

Expected: Plugins land under ~/.claude/plugins/ (or the equivalent per-user dir). Never under /usr. Non-root install/enable/disable works without sudo.

Diagnostics on failure: find / -name '*<plugin-name>*' 2>/dev/null, install logs, launcher log.

References: Install plugins

Code anchors: build-reference/app-extracted/.vite/build/index.js:283107 cE() resolves the config root to CLAUDE_CONFIG_DIR or ~/.claude — never /usr; :465815 dx() returns <cE()>/plugins; :465821/:465824/:465827 installed_plugins.json, known_marketplaces.json, marketplaces/ all sit under dx(). No system-path writes in the install path.

S28 — Worktree creation surfaces clear error on read-only mounts

Severity: Could Surface: Worktree creation on read-only filesystem Applies to: All rows (NixOS users hit this most often) Issues: —

Steps:

1. Place a project on a read-only mount (e.g. squashfs, NFS read-only export, mount -o ro bind).
2. Open a Code-tab session against it.
3. Try to start a parallel session that needs a worktree.

Expected: Worktree creation fails with a clear error pointing at the read-only mount. No silent loss of work, no writes to a wrong directory, no parent-repo corruption.

Diagnostics on failure: mount | grep <project-path>, git worktree add direct invocation (does it fail the same way?), launcher log, screenshot of error dialog.

References: Work in parallel with sessions

Code anchors: build-reference/app-extracted/.vite/build/index.js:462841 worktree parent dir is <repo>/.claude/worktrees (or chillingSlothLocation.customPath override at :462836); :462928 git worktree add failure path returns null after R.error("Failed to create git worktree: …"); :462760 Sbn() classifies "Permission denied" / "Access is denied" / "could not lock config file" as "permission-denied" (the read-only-mount taxonomy bucket).