opencode

opencode × Nika

Verified live 2026-07-09 · opencode 1.17.5 · nika 0.98.0.

opencode reads AGENTS.md natively — so the project scaffold IS the integration:

nika init    # writes AGENTS.md + editor rules + the authoring skill

That one command teaches any opencode session the house law: author → nika check → run budget-capped → nika trace verify. Division of labor: opencode writes code; Nika runs the repeatable work as a checkable file with receipts.

The MCP oracle (optional)

For schema/validation answers without shell round-trips, add the read-only oracle to opencode.json at the project root — nika wire opencode writes it for you (0.99+), or copy opencode.json from this folder:

{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "nika": {
      "type": "local",
      "command": ["nika", "mcp"],
      "enabled": true
    }
  }
}

Two facts we verified live so you don't have to:

• opencode prefixes MCP tool names with the server key — in-session the oracle's tools appear as nika_nika_check, nika_nika_explain, … A prompt that says "call nika_check" verbatim will miss; say "the nika tools".
• The deterministic check is opencode mcp list → ✓ nika connected. Trust that line, not a model's enumeration — small local models can invent tool names instead of reading them.

The oracle validates and teaches; running workflows stays on the terminal, where --max-cost-usd, effect permits and the trace live. Nine tools ride tools/list and nothing else does — prompts/list is not served at 0.106.0, so the /nika:* slash commands are a plugin feature, not an MCP one.

Three things a session gets wrong from memory

An opencode session writing its first .nika.yaml from training data usually trips on the same three. Each is a refusal at nika check, before a token is spent — but knowing them saves the round trip:

• The envelope is closed. Thirteen keys, additionalProperties: false; the two older catch-all value blocks are retired (NIKA-VALUES-001 / -002). A parameter the caller supplies is an inputs: declaration, a fixed value is a const: entry, deployment settings are config:, and credentials are secrets: references. nika check <file> --fix migrates what it can prove.
• permits: absent means ZERO authority, not unrestricted. An exec:, a fetch or a file write with no grant refuses with NIKA-AUTH-006. Pure compute says permits: {}; everything else gets the block nika check <file> --infer-permits prints.
• A builtin usually beats exec:. nika catalog --tools lists what an invoke reaches with no MCP server at all — HTTP, files, JSON, hashing, charts. nika check --native-strict fails the file on an exec: a builtin already covers.