@obsigna/opencode-plugin

OpenCode plugin for Agent Receipts. Emits one cryptographically signed receipt per native tool call (bash, edit, write, webfetch, …) by forwarding each call to obsigna-daemon over a Unix-domain socket. The daemon — not this plugin — holds the key, canonicalises, signs, and chains the receipt.

This is the OpenCode analog of the obsigna-hook Claude Code integration, covering the native-tool channel. MCP tool calls are covered separately by mcp-proxy.

Trust boundary

The plugin runs inside the OpenCode process, so it is an emitter only — it never instantiates a signer, signs, or holds a key (ADR-0010, daemon-sole-writer). This is the execd-side, honest-operator placement: it maximises coverage of native tool calls, but it is not adversary-resistant. A compromised OpenCode can omit or misreport calls. For the adversary-resistant MCP placement, point OpenCode's MCP server config at mcp-proxy (Tier A — see the docs).

Install

npm install @obsigna/opencode-plugin

Register it as an OpenCode plugin in opencode.json:

{
  "plugin": ["@obsigna/opencode-plugin"]
}

Requires obsigna-daemon to be running. See the OpenCode docs for the full Tier A + Tier B walkthrough and an end-to-end obsigna verify example.

Configuration

Configure via environment variables (read at plugin load):

| Variable | Default | Meaning | |---|---|---| | AGENTRECEIPTS_SOCKET | per-OS default | Daemon socket path | | AGENT_RECEIPTS_CHANNEL | opencode | Receipt channel label | | AGENT_RECEIPTS_STRICT | false | Re-throw on emit failure (ADR-0025) instead of warn | | AGENT_RECEIPTS_ALLOW | — | Comma-separated tool allow-list | | AGENT_RECEIPTS_DENY | — | Comma-separated tool deny-list |

For programmatic configuration (allow/deny, action-type overrides, custom logger), build the plugin with createObsignaPlugin(config) and export it from your own .opencode/plugin/ file.

Failure posture (ADR-0025)

Default is catch-and-warn: a tool call is never aborted because the daemon is unreachable — the drop is logged loudly. Best-effort emission means a daemon outage produces a chain gap, not a completeness guarantee; this is honest-operator-grade auditing. Set AGENT_RECEIPTS_STRICT=1 to surface emit failures instead.

Development

pnpm install   # installs deps, including @obsigna/sdk-ts from npm
pnpm build     # tsc → dist/
pnpm test      # vitest
pnpm typecheck # tsc --noEmit
pnpm lint      # biome check

License

Apache-2.0 — see LICENSE.