runner_attach
Attach to a live runner tmux session — flip it into user-driven mode so the keeper does NOT nudge while you're vibing.
This record as markdown: /tools/io-github-kivanccakmak-yaver/runner-attach.md
What runner_attach does on Yaver
AI agents invoke runner_attach to trigger actions in Yaver. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call: builds kicked off, notifications sent, workflows started.
| Parameter | Type | Required | Description |
|---|---|---|---|
machine | string | — | Reserved for future remote-attach routing (empty = local). |
sessionName | string | Yes |
Parameters from the server's own tool schema.
Why runner_attach is rated High
This tool attaches to a live tmux session and changes its operational mode (disabling automated 'keeper' interventions). It triggers an external operation affecting a running process/session, which is characteristic of Execute. The blast radius is medium since it modifies the behavior of a live runner session but does not directly delete data or move money.
From the tool's definition Attach to a live runner tmux session — flip it into user-driven mode so the keeper does NOT nudge while you're vibing.
Attacks that exploit this kind of access
The rule that runs runner_attach safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Yaver, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For runner_attach, this is the rule to start with:
runner_attach stays usable, but rate-capped: a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Yaver, apply this rule, and every runner_attach call is checked against it from then on.
Questions about runner_attach
Attach to a live runner tmux session — flip it into user-driven mode so the keeper does NOT nudge while you're vibing. It is categorised as a Execute tool in the Yaver MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
runner_attach accepts 2 parameters: machine, sessionName. Required: sessionName. The full parameter table on this page comes from the server's own tool schema.
Register the Yaver MCP server in PolicyLayer and add a rule for runner_attach: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Yaver. Nothing to install.
runner_attach is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the runner_attach rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for runner_attach. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
runner_attach is provided by the Yaver MCP server (yaver-cli). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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