Use case · Free plugin

# My agent ran the tests and the log filled the window. *Now the model reads the failing tests.*

The free context-mode plugin runs test, lint and build output in a sandbox on your machine. A short script picks the failing tests, the error lines and the counts. On a Vite run of 1,106 tests, 61.4 KB of output reached the model as 0.4 KB.

[Install the free plugin](https://contextmode.ai/docs/engine/install) [Read the docs](https://contextmode.ai/docs/engine/sandbox)

Run the tests and fix what is red.

Full log Free plugin

Full log: every test name, stack trace and timing line reaches the model.

The run prints **61.4 KB** The model reads **61.4 KB**

Every later call sends it again.

Free plugin: a script reads the log in a sandbox on your machine.

The script reads **61.4 KB** The model reads **0.4 KB**

Sent to the model

- The 25 failing tests, the first error of each and the file to open

Kept on your machine

- The full 61.4 KB log, searchable with ctx_search

The problem

## The answer is a short list. *The log is long.*

**Every test prints a line**

A verbose run prints each test name, each stack trace and each timing line.

**The agent needs a few lines**

The failing tests, the first error of each and the file to open.

**The log stays in the thread**

Text in the conversation goes back to the model on every later call of the session.

How it works

## A script reads the log. *The model reads the list.*

1. 01 **The output goes to the sandbox** Your agent calls `ctx_execute` with the command, or the PostToolUse hook catches a large shell output.
2. 02 **A short script reads it** The agent writes the script. It prints the failing tests and their first error line.
3. 03 **The model reads the print** The full output goes into a SQLite FTS5 index in `~/.context-mode`. The agent finds a stack trace later with `ctx_search`.

Proof

## Five logs, measured. *The model reads under 1 KB of each.*

| Log | Full output | The model read | Time |
| --- | --- | --- | --- |
| Test run, 1,106 tests, 25 failing ( `vitest run --reporter=verbose` , vitejs/vite) | 61.4 KB | 0.4 KB | 60 ms |
| Lint report as JSON ( `biome lint --reporter=json` , packages/vite/src) | 281.8 KB | 0.6 KB | 65 ms |
| Workspace install log ( `pnpm install --frozen-lockfile` , vitejs/vite) | 14.6 KB | 0.2 KB | 59 ms |
| Database server log ( `docker logs` , mongo:8.0 --verbose) | 59.0 KB | 0.6 KB | 62 ms |
| Infrastructure plan ( `terraform plan` , 72 resources) | 33.3 KB | 0.2 KB | 62 ms |

Plugin benchmark of 2026-11-01 on an Apple M1 Pro, default settings, median of 5 runs. Raw data: [the result tables](https://contextmode.ai/benchmarks/engine/2026-11-01-usecases.md). Rerun it with the steps on [Benchmarks](https://contextmode.ai/docs/engine/benchmarks).

Prompts

## Give your agent *one of these.*

Prompt

```
Run the full test suite. Give me each failing test, its first error line and the file to fix. Then fix them one at a time and run the suite again.
```

Prompt

```
Run the linter on src. Group the findings by rule, show the count for each rule, and fix the rule with the most findings.
```

Prompt

```
Run terraform plan and list each resource it will replace or destroy, with the reason the plan gives.
```

Products used

## What this *uses.*

**[The free plugin](https://contextmode.ai/engine)**

Open source. It runs in your agent, on your machine.

**[Sandbox](https://contextmode.ai/docs/engine/sandbox)**

Where the command runs and what comes back.

**[Search and index](https://contextmode.ai/docs/engine/search)**

How the agent finds a line in the full log later.

**Related**

[Free plugin resources](https://contextmode.ai/open-source/resources) · [Issue triage](https://contextmode.ai/use-cases/issue-triage) · [Docs research](https://contextmode.ai/use-cases/docs-research)

## Read the failing tests. *Keep the full log on your machine.*

Each agent installs the free plugin with its own install command.

[Install the free plugin →](https://contextmode.ai/docs/engine/install) [Source on GitHub →](https://github.com/mksglu/context-mode)