Wiring Contract

Answer one question for this project and then keep answering it automatically: when something is built here, what does it have to be connected to before it counts as done?

The failure is not carelessness, it is structural. A model's context makes it unable to see whether the element it just generated is referenced anywhere else, so plausible-but-unreferenced code is the expected output. Across 304,362 verified AI-authored commits in 6,275 repositories, "unused variables or parameters" is the second most frequent issue class, and "undefined variable or reference" — writer and reader disagreeing about a name or path — is the most common runtime bug category. It does not wash out: AI-authored code survives longer than human-written code (53.9% vs 69.3% line death rate), so an orphan is less likely to be cleaned up than a human's.

Every ordinary signal misses it. Tests pass, coverage rises, lint is clean, review approves — because each of those verifies a thing against itself, and wiring is a property of a pair.

When to Use

• At L3, before implementation — the walking-skeleton obligation (G-V13). A design is not complete until its joins are named.
• On an existing project, once, to discover what conventions it already has.
• After a structural change (new directory, new layer, a move) — regenerate, never hand-edit.
• When check_wiring_contract.py reports UNGOVERNED files you did not expect.

Workflow

1. Detect — read the repo's own majority convention

python3 "${CLAUDE_PLUGIN_ROOT}/scripts/check_wiring_contract.py" --root . --detect

This proposes a rule only where the repo already behaves that way, and records the evidence:

- id: wc-002
  pattern: "scripts/*.py"
  obliges:
    - referenced_by: ["**/*"]
  detected_from: "18 of 20 files already satisfy this"
  confidence: 0.90

A rule without observed support is a preference, not a contract. Two obligation types exist and that is deliberate — referenced_by (something outside the file references it, by import, invocation, path, or a glob that matches it) and sibling_reference (a same-directory barrel or registry lists it). Nine specific obligations rot; two general ones that always run do not.

2. Review with the human — this is a draft, not a finding

Present the proposal and ask, per rule, in plain language: "18 of 20 scripts here have a caller. Should that be required?" Watch for two failure shapes:

• A majority that is an accident. Four files in a directory that happen to be referenced does not make referencing them a rule. Ask what the directory is for.
• A convention the detector cannot see. Files invoked by reflection, by a registry built at runtime, or by a config string are wired and will look orphaned. These need an exemption with a reason — and "it is hard to check" is not one.

Write the confirmed contract to .claude/harness/wiring-contract.yml. Per the evidence-writes rule, the contract is a human-confirmed draft, never written unattended.

3. Enforce — and put it where the agent will feel it

python3 "${CLAUDE_PLUGIN_ROOT}/scripts/check_wiring_contract.py" --root .

Per G-V14, add this to the command run after every change, not only to CI. Agents respond to automated signals far more reliably than to documentation: a failing command gets fixed, a guardrail paragraph in the context window may not be read at all.

4. Read the UNGOVERNED count — it is the load-bearing number

Files matching no rule are listed with a count. Zero violations across a governed subset is not zero violations. A clean report beside 300 ungoverned files describes the health of a fraction while implying the whole — the precise false green this skill exists to end. Either extend coverage or state why those files are outside it.

Output

• Creates/updates: .claude/harness/wiring-contract.yml (human-confirmed)
• Reports: violations, and the ungoverned count
• Feeds: /mycelium:definition-of-done (G-V14 verification block), /mycelium:bvssh-check (CALMS Automation wiring_integrity)

Theory Citations

• Cockburn — walking skeleton: "a tiny implementation of the system that performs a small end-to-end function… it should link together the main architectural components." Wiring exists before features.
• Hunt & Thomas — tracer bullets: the same instinct, framed as end-to-end feedback first.
• Ford, Parsons, Kua — architecture fitness functions: objective, continuously-executed measures of properties the design must preserve. This check is one, and belongs in the pipeline rather than in a review checklist.

Deliberately NOT a catalogue

Mycelium does not ship a list of integration points to check. A sibling project hand-listed 4 component and 9 plugin integration points; such a list is stale the moment someone adds the tenth, and hand-enumerated scope is the origin of this entire failure family. The rules here are derived from the project in front of you, and regenerated when it changes.