| name | configure-opencode-frontend |
| description | Configure opencode as the frontend builder in the three-agent AgentCore harness. Use for deploying the opencode Runtime, staging AGENTS.md and .config/opencode/opencode.json, or verifying that the generated interface resolves its service address at runtime and delegates work to the backend MCP server. opencode runs Bedrock-native (amazon-bedrock provider, claude-sonnet-4-6) with no API key. |
Configure the opencode frontend builder
opencode builds the frontend interface. Claude Code builds the backend and Kiro
(the validator) validates the composed result. There is no race and no winner.
Prerequisites
coding-agents/infra.config exists.- The
amazon-bedrock provider can reach claude-sonnet-4-6 in us-west-2.
- The Runtime execution role can use the AWS SDK credential chain.
- Docker Buildx or Finch can build arm64 images.
opencode does not need an API key, AgentCore workload identity, or API-key
credential provider. The Runtime IAM role is the authentication path (the CLI
signs its Bedrock calls with the role's temporary credentials).
Deploy
cd coding-agents/opencode
./setup.sh
python deploy.py
runtime_config.json must contain a Runtime ARN and the Runtime must reach
READY before continuing.
Stage project guidance
Copy the whole project configuration so hidden settings are preserved:
cp -R orchestrator/harness/opencode/. /mnt/s3files/
test -s /mnt/s3files/AGENTS.md
test -s /mnt/s3files/.config/opencode/opencode.json
The root AGENTS.md defines the frontend role. The hidden
.config/opencode/opencode.json selects the amazon-bedrock provider and
the claude-sonnet-4-6 model.
The thin-client rule (why it is a browser fact, not a preference)
Any interface the frontend builds must resolve its service address at RUNTIME,
never at build time. This is not a use-case preference; it is a browser constraint:
localhost and 127.0.0.1 in a page mean the machine running the BROWSER.
A URL baked at build time is dead the moment the page moves to any other host.- A cross-origin JSON POST is preflighted by the browser. The service must answer
OPTIONS with the correct Access-Control-Allow-Origin header or the browser
will block the request before it reaches the server.
These constraints hold for every interface the frontend produces, regardless of the
task. The agent should read the service address from an env var or a config endpoint
at startup, not embed it in source.
Verify
agentcore exec --it \
--runtime "$(jq -r .runtime_arn coding-agents/opencode/runtime_config.json)" \
--region us-west-2
Inside the Runtime, run /app/run.sh and give opencode the task. Verify that the
produced interface resolves the backend service address at runtime (not hardcoded),
delegates backend work to the MCP server via tools/call, and handles OPTIONS
preflight correctly if it runs cross-origin. Do not claim completion until the
interface loads and a round-trip through the backend succeeds.
Reference: https://opencode.ai/docs/
