Install Context Mode in Claude Code and check its session output

Context Mode is a third-party Claude Code plugin that routes some large tool results through its own tools and keeps a local index of session events. A developer can use it to inspect what reached the conversation during a coding task. Its statistics describe the plugin's handling of tool output; the changed files and the task's acceptance checks still determine whether the work is sound. This guide follows the maintainer's version 1.0.169 files and Claude Code's current plugin instructions, checked on 20 October 2026. BIG CHANGE did not install the plugin or run a coding session for this article.

The big change

• What changed: A Claude Code plugin can intercept selected tool calls, keep larger results outside the conversation and index session events for later retrieval. The installed marketplace version and active hooks have to be checked in the reader's own session.
• Why it matters: On a long coding task, a developer can compare the plugin's record of routed output with the actual files and test results. That gives a way to judge whether filtering preserved the evidence needed for a decision, instead of accepting a compression figure as proof of useful work.
• What to watch: The decisive check is whether the intended tool calls route in the installed environment and whether the original evidence remains accessible after a compacted or resumed session. The plugin's local report cannot establish provider charges or code correctness.

Before installing

Use an authorized Claude Code terminal session and a repository you are allowed to change. Pick a bounded coding task with a known completion check: the relevant files, an existing test or build command, and the behavior that must remain intact. If you need a baseline for Claude Code's built-in session controls, our guide to inspecting context and continuing a session covers /context and /compact without this plugin.

In your terminal, record the installed Claude Code and Node.js versions:

claude --version
node --version

The pinned plugin package requires Node.js 22.5.0 or later. Its Claude Code manifest starts the MCP server with node. Check that Node is available to Claude Code's plugin process, then open an interactive session and confirm /plugin is available. If it is missing, follow the setup instructions for your Claude Code distribution; the maintainer README's older minimum version is not a reliable compatibility test for current controls.

Use a platform where this plugin's Bash hook can run: macOS, Linux, WSL, or Windows with Git Bash configured for Claude Code. Claude Code itself can run on native Windows with PowerShell, but the pinned hook matchers name Bash, not PowerShell. Automatic routing through a PowerShell-only tool path has not been established by these files.

Get permission to install a third-party plugin in the workspace. Review its Elastic License 2.0, hook commands and server manifest against your organization's rules. Claude Code says plugin hooks and MCP servers run with the user's privileges outside its tool sandbox; approval of a model tool call does not sandbox those processes. The plugin can process repository content and inherits the user's available files and credentials. Local indexing also does not mean that selected prompts and results stay away from the chosen model provider. Check the account's data-use terms before using sensitive material.

1. Install at an intentional scope

Inside the interactive Claude Code session, enter these commands:

/plugin marketplace add mksglu/context-mode
/plugin install context-mode@context-mode

The second command opens the plugin details panel under Claude Code's current install flow. Inspect the listed skills, hooks and MCP server. Choose local scope for a trial confined to you in this repository, unless a wider scope has been authorized. User scope enables the plugin across your projects; project scope enables it for collaborators who install it. Read the install summary and the /plugin Errors tab. Follow the stated reload instruction or restart Claude Code. A forced /reload-plugins --force can invalidate the prompt cache and incur an uncached request, so use it only when you want activation in the current session.

Confirm that Context Mode appears on /plugin's Installed tab with the intended scope. From a separate terminal, record the actual installed version and status:

claude plugin list

The research snapshot is version 1.0.169 at repository commit b31c7ee853cb9ea76121e24d368599390972a997; the marketplace command does not pin that commit. Use the version you actually installed when judging any changed command or behavior. The maintainer's separate npx MCP-only route supplies tools without the plugin's automatic hooks, so it is not equivalent to this installation.

2. Diagnose the installed plugin

In the active Claude Code session, run:

/context-mode:ctx-doctor

Keep the complete report. The pinned doctor skill labels results [OK], [FAIL] and [WARN]. Check the runtime, hook registration, SQLite FTS5 search support, plugin registration and version lines. Resolve a failure by its named cause. A missing skill or server calls for the /plugin Errors tab and Claude Code's plugin troubleshooting guide. A passing doctor report establishes setup diagnostics; the next step checks whether routing actually occurs during your work.

3. Observe routing on a real task

Before the task, save its goal, acceptance check and repository state. These terminal commands can help you identify existing changes without claiming they belong to the plugin:

git status --short
git diff --stat

In the Claude Code session, run /context-mode:ctx-stats and keep the full starting report. Then carry out the authorized coding task. Watch the actual tool names and returned results: did qualifying reads, searches, shell commands or MCP calls use Context Mode tools, and can you retrieve original details that a filtered result omitted? Run the same stats command afterward:

/context-mode:ctx-stats

The stats skill reports current-session output and a per-tool breakdown. If there were no qualifying calls, an empty report shows no observed plugin effect. Keep both reports with the task record and compare them with the calls you saw. The maintainer's compression and session-duration figures are its own examples, not measurements of your task. The plugin's token or context estimates are neither a provider invoice nor evidence that the model made correct edits. Claude Code and model usage still follow your account or provider terms.

If the conversation compacts or you resume it, inspect the recovered task state before allowing another edit. Check the actual files, the diff and the original acceptance command; retrieve any full tool result needed to judge a filtered excerpt. Context Mode's local event index can help locate an earlier decision, but its recalled state does not verify the repository. Finish by running the task's real check and reviewing the resulting diff yourself. Record the command, exit result, affected files and any unresolved failure. A session report can be useful even when the task fails; it must not turn that failure into a pass.

4. Recover without discarding evidence

If routing blocks a needed tool, retain the exact error and doctor report, then inspect /plugin's Errors tab. If the issue is the plugin, disable Context Mode from /plugin's Installed tab at the scope that enables it. Local, project and user settings have different reach and precedence. Start a fresh Claude Code session, confirm the plugin is disabled there, and check that the ordinary tools and your actual task state are usable. Preserve the reports and source output needed to explain what happened.

Disablement does not delete the local index. The plugin's purge skill describes a deliberate, irreversible /context-mode:ctx-purge operation. Session scope requires the exact session ID and removes that session's rows and search chunks while preserving sibling sessions and project stats. Project scope removes the project's indexed content, all project-session events, event files and stats. Decide and confirm the intended scope only after retaining evidence you need; neither purge is a routine troubleshooting step. /clear and /compact do not erase Context Mode's stored data.

Sources & further reading

• Context Mode README at the researched commit documents the marketplace route, tools, indexing and maintainer performance examples. Its examples were not reproduced for this guide; actual installed version and output must be checked locally.
• Context Mode package, plugin manifest and hook configuration establish the pinned runtime, license identifier, MCP launch and named hook matchers. The manifest and hooks are linked at the relevant steps above.
• Claude Code's plugin install guide explains the details panel, install scopes, status, reload and disable controls. Security and trust explains the execution boundary; it does not audit this third-party plugin for your workspace.
• Context Mode's doctor, stats and purge skills define the reported diagnostic, session-statistics and deletion behavior at the researched revision. They do not establish a successful coding result in any reader's installation.