civiltekk-opencode-creation-skill

Consolidates opencode-agent-creation-skill + opencode-skill-creation-skill (#603).

What I do

Create or edit OpenCode artifacts — agents and skills — to the official
documentation standards each variant file carries:

1. Detect artifact type (agent vs skill) — explicit > inferred >
   ask-once. Explicit: the request says "agent"/"subagent" or "skill".
   Inferred: the target shape (<name>.md with agent frontmatter → agent;
   skills/<name>/SKILL.md → skill). Ambiguous ("create an artifact/tool")
   → ask once — one ask per run, then proceed on the answer.
2. Route to the artifact variant (§Routes).
3. Load the variant values file (references/agent.md /
   references/skill.md) and author or edit per its contract.

Side files (load rules)

Read	When	Use
references/agent.md	variant is agent	required/config frontmatter keys and per-key rules, tier-aware model guidance, temperature/steps tables, permission patterns, body (system-prompt) structure, project vs global scope, name validation, examples, verification commands
references/skill.md	variant is skill	skill frontmatter contract, lean content standard + line budgets, content structure, skill permissions (v2), portability rules, file safety, verification

Side files carry VALUES only; this file carries the METHOD. An artifact type
outside agent/skill (plugin, MCP config, opencode.json, …) is not this
skill's variant space — route it to opencode-tooling-subagent instead of
improvising a variant.

Routes

Situation	Variant
"generate/edit an agent", "create a subagent", agent-shaped target file	agent
"generate/edit a skill", "create a SKILL.md", skill-shaped target dir	skill
Ambiguous ("create an artifact/tool")	ask once (§What I do step 1), then route

Boundaries

• Tier/model resolution belongs to the installer's agent-tiers.json, not
  here. The agent variant cites it for model guidance; never re-derive,
  re-rank, or re-assign tiers from this skill, and never default a subagent
  to the primary tier.
• Registry rebuild after frontmatter changes: any skill frontmatter
  change requires node installer/build-registry.mjs and a committed
  registry.json.
• Editing an existing artifact: read before write/edit — write
  overwrites silently.

Agent behavior rules

• Follow the official-docs best practices each variant file carries — the
  loaded variant file is the authority for its artifact type; when it conflicts
  with memory, re-fetch the current official docs rather than guessing.
• Never invent frontmatter keys — unknown keys are silently ignored by
  OpenCode; emit only the keys the variant file lists.
• Ask, don't invent: a missing required field (name, description, mode /
  purpose) → one batched question round. Headless/CI: no asks — proceed only
  if every required field arrived in the original request, otherwise fail
  naming the missing fields.

Harness binding — interactive asks (AGENTS.md §Portability contract):
OpenCode — question tool. Claude Code — AskUserQuestion. Other/none —
batch the same questions in a plain reply; proceed per the headless rule
above if no answer comes.