# ax-problem One error shape for every agent surface: the CLI's stderr line, its `--json` error and an MCP tool error all carry the same fields, so an agent learns one repair loop. The line mirrors Ouro HX's dev message format: `: : . Fix: .` ```sh npx shadcn@latest add ourostack/ouro-ui/ax-problem#v1.3.10 ``` It installs `lib/ouro/ax/problem.ts`. Its tests are `ax-problem-tests`. Every item runs on Node 22.18 or later as it is copied: the files import each other as `./.ts`. The [Ouro AX guide](ax.md) shows how they fit together. ## Exports ### `AxError` The error the kit's primitives throw: its message is the one line, its shape the data. ```ts class AxError extends Error ``` ### `AxErrorBody` The error as data: its shape plus the one-line message. Outcomes, `--json` and MCP all carry this. ```ts type AxErrorBody = AxErrorShape & { message: string }; ``` ### `AxErrorShape` One error shape for every agent surface: the CLI's stderr line, its `--json` error and an MCP tool error all carry the same fields, so an agent learns one repair loop. The line mirrors Ouro HX's dev message format: `: : . Fix: .` ```ts interface AxErrorShape { code: string; exit: number; thing: string; problem: string; fix: string | null; } ``` ### `commandLine` A command line from words, each quoted only when it needs it. ```ts function commandLine(words: readonly string[]): string ``` ### `didYouMean` The candidate an agent most likely meant: a unique prefix, or the nearest within two edits; null when none is close. ```ts function didYouMean(word: string, candidates: readonly string[]): string | null ``` ### `errorJson` The `--json` and MCP form: `{ error: { code, exit, thing, problem, fix, message } }`. ```ts function errorJson(shape: AxErrorShape): { error: AxErrorBody; } ``` ### `errorLine` The one stderr line: `: : . Fix: .` Line breaks in any part become spaces. ```ts function errorLine(tool: string, shape: Pick): string ``` ### `errorMessage` `: . Fix: .`, without the tool's prefix (a CLI adds its own). ```ts function errorMessage(shape: Pick): string ``` ### `isAxError` ```ts function isAxError(value: unknown): value is AxError ``` ### `shellWord` Quotes a word for a POSIX shell only when it needs it, so a fix copies and runs as printed. ```ts function shellWord(word: string): string ```