AugmentClaude
BackendDevOps

Harness Diagnostic

By ruvnet· ruvnet/agent-harness-generator· 0

Check if your local kernel matches the harness scaffold version.

Installation

  1. Make sure Claude is on your device and in your terminal.

    Skills load from ~/.claude/skills/ when Claude Code starts up — so you need it on your machine first. If you don't have it yet, install it once with the command below, then run claude in any terminal to verify.

    One-time setup
    npm i -g @anthropic-ai/claude-code

    Already have it? Skip ahead.

  2. Paste into Claude Code or into your terminal.
    Install
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    This copies the whole skill folder into ~/.claude/skills/diag-harness-ruvnet/ — the SKILL.md plus any scripts, reference docs, or templates the skill ships with. Safe default: works for every skill.

    Faster alternative (instruction-only skills)

    Skips the clone and grabs only the SKILL.md file. Don't use this if the skill ships Python scripts, reference markdowns, or asset templates — they won't be downloaded and the skill will fail when it tries to load them.

    Quick install (SKILL.md only)
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  3. Restart Claude Code.

    Quit and reopen Claude Code (or any other agent that loads from ~/.claude/skills/). New skills are picked up on startup.

  4. Just ask Claude.

    Skills auto-activate when your request matches the skill's description — no slash command needed. Trigger phrases live in the skill's own frontmatter; you can read them in the “What this skill does” section above.

Prefer to read the source first? Open on GitHub.

When Claude uses it

Kernel-version skew check (ADR-027). Reports manifest surface + manifest kernel + installed kernel + verdict (match/patch-diff/minor-diff/major-diff). Exits 1 on minor/major skew with a copy-pasteable `npm install @metaharness/kernel@X.Y.Z` next step. Exits 2 if no .harness/manifest.json at path.

What this skill does

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:

FieldSourceMeaning
meta.surfaceiter 56Which surface produced the harness (cli or web-ui)
meta.kernel_versioniter 58The @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.

VerdictExitMessage
match0PASS kernel versions match exactly
patch-diff0WARN patch-level skew (usually safe; may include bugfixes)
minor-diff1WARN minor-level skew (new kernel features may be missing) + Run: npm install @metaharness/kernel@X.Y.Z
major-diff1FAIL MAJOR skew — APIs may have changed; expect breakage + Run: npm install @metaharness/kernel@X.Y.Z
no .harness/manifest.json at path2FAIL no .harness/manifest.json found at this path

Usage from Codex

/diag-harness                           # cwd
/diag-harness path=./my-harness

Equivalent CLI

harness diag                            # cwd
harness diag ./my-harness               # explicit path
harness diag ./my-harness --json        # machine-readable for CI
harness diag ./my-harness --bundle      # support-ticket JSON (iter 90)

The --bundle form (iter 90) emits a single JSON snapshot of the diag report + sanitised manifest + @metaharness/* deps + Node/platform info — everything a maintainer needs to triage a bug report. Object keys matching secret|token|key|password|api_key are redacted so the bundle is safe to paste into a public GitHub issue.

Sample output

harness diag — checking /tmp/my-harness

  surface:              cli
  manifest kernel:      0.1.0
  installed kernel:     0.1.0

  PASS kernel versions match exactly

When to run

  • After cloning someone else's harness — first thing
  • After bumping @metaharness/kernel in a harness's package.json
  • When harness doctor fails with cryptic shape errors (skew is the usual cause)
  • In CI before any other harness subcommand — fail fast

Lifecycle position

scaffold (create-agent-harness)
    ↓
 your code lives in the harness
    ↓
 diag (this skill)           <- before anything else, check compatibility
    ↓
 doctor / validate / sign / publish

Related

  • ADR-027 — CLI ↔ Web-UI integration (the parity contract diag enforces)
  • iter 56 — manifest.meta.surface added
  • iter 58 — manifest.meta.kernel_version stamped at scaffold time
  • iter 66 — harness diag subcommand

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