Errors that say the fix

A stable code tells an agent what went wrong. Now it also says what to do: the error line carries docs, a link to that code’s fix.

$ vx run biuld --all --format json
{"ok":false,"error":{"code":"VX_E_UNKNOWN_TASK","message":"vx run: no projects declare task(s): biuld. Did you mean build?","docs":"https://vznjs.github.io/vx/cli/#vx_e_unknown_task"}}

No network? The same section ships inside vx:

$ vx docs VX_E_UNKNOWN_TASK
── cli.md § VX_E_UNKNOWN_TASK · https://vznjs.github.io/vx/cli/#vx_e_unknown_task

#### `VX_E_UNKNOWN_TASK`

No project in scope declares a requested task. The message lists the
tasks it found; `vx show --format json` lists each project's. …

Code	The fix says
VX_E_USAGE	the flag it refused; vx <verb> --help
VX_E_CONFIG	the file and field; vx docs <field>
VX_E_CYCLE	the loop; drop one dependsOn edge
VX_E_NO_HISTORY	run the task once first
VX_E_FDS	ulimit -n 4096, or fewer tasks at once

Every core code has its section, and a test holds the list to the codes the source can throw. Over MCP, a refused tool call carries the same docs link.

Error codes · Agents guide