diag-harness

# diag-harness > Codex skill: kernel-version skew check for a scaffolded harness — the ADR-027 diagnostic UX loop. ## What it does Single-question check: **does my local `@metaharness/kernel` match what this harness was scaffolded against?** That's the cross-machine compatibility question almost every "this harness doesn't work" support ticket turns out to be. Reads `.harness/manifest.json`: | Field | Source | Meaning | |---|---|---| | `meta.surface` | iter 56 | Which surface produced the harness (`cli` or `web-ui`) | | `meta.kernel_version` | iter 58 | The `@metaharness/kernel` version stamped at scaffold time | Resolves the local `@metaharness/kernel` via `createRequire` rooted at the harness's own `package.json` (real Node resolution). Computes the skew verdict and prints a copy-pasteable next step. | Verdict | Exit | Message | |---|---|---| | `match` | 0 | `PASS kernel versions match exactly` | | `patch-diff` | 0 | `WARN patch-level skew (usually safe; may include bugfixes)` | | `minor-diff` | 1 | `WARN minor-level skew (new kernel features may be missing)` + `Run: npm install @metaharness/kernel@X.Y.Z` | | `major-diff` | 1 | `FAIL MAJOR skew — APIs may have changed; expect breakage` + `Run: npm install @metaharness/kernel@X.Y.Z` | | no `.harness/manifest.json` at path | 2 | `FAIL no .harness/manifest.json found at this path` | ## Usage from Codex ``` /diag-harness # cwd /diag-harness path=./my-harness ``` ## Equivalent CLI ```bash har...