Agentcore Harness Slackbot

AgentCore Harness Slackbot

Stop and obtain consent

Before creating, deploying, or changing resources, tell the user:

This skill installs a sample/reference Slack adapter, not production-ready software. It creates real AWS resources, including an AgentCore Harness, API Gateway, Lambda, SQS, Secrets Manager, CloudWatch Logs, and model invocations. These resources incur charges. Slack workspace configuration also changes. Review security, retry semantics, data handling, monitoring, and cleanup before production use.

Wait for an explicit yes. If the user only wants an explanation, explain without running resource-changing commands.

Outcome

Create or reuse one declarative AgentCore Harness and connect it to Slack through:

Slack Events API
  -> API Gateway HTTP API
  -> ingress Lambda (signature verification and quick acknowledgement)
  -> SQS FIFO
  -> worker Lambda
  -> InvokeHarness on a named endpoint
  -> Slack startStream / appendStream / stopStream

Keep the Harness channel-neutral. Do not export it to a custom runtime merely to support Slack. The adapter consumes the Harness event stream and owns Slack-specific delivery.

This template intentionally omits DynamoDB delivery leases and durable stream checkpoints. SQS deduplicates the same Slack event for five minutes, but a worker failure after Slack accepts a stream call can still create a duplicate on retry. Read references/architecture-and-hardening.md before describing this as production-ready.

Bundled resources

• scripts/scaffold_slack_adapter.py: copy and render the generic adapter template into a customer's AgentCore project.
• scripts/ensure_harness_endpoint.py: create or update a named Harness endpoint from agentcore/.cli/deployed-state.json, then wait until it is ready.
• assets/slack-adapter-template/: standalone Python Lambda and TypeScript CDK project, focused tests, and two Slack manifests.
• references/slack-setup-and-troubleshooting.md: Slack bootstrap cycle, secrets, test procedure, and common errors.
• references/architecture-and-hardening.md: trust boundaries, delivery limitations, data handling, and the path from sample to production.

Prerequisites

Confirm:

• AgentCore CLI is installed: agentcore --version.
• AWS credentials point at the intended account: aws sts get-caller-identity.
• The target region is explicit in agentcore/aws-targets.json.
• Node.js 20 or newer and npm are available.
• Python 3.12 or newer with boto3>=1.43.39,<2 is available for the endpoint helper.
• Docker or Finch is running for CDK's Lambda dependency bundle.
• The user can create and install a Slack app in the target workspace.

Do not accept account IDs, ARNs, Slack tokens, signing secrets, or workspace IDs copied from another customer or example. Discover them from the current project and workspace.

Step 0: Inspect before changing

Read the project AGENTS.md, agentcore/agentcore.json, the Harness directory, and agentcore/.llm-context/ types. Check git status and preserve unrelated changes.

Determine whether the customer has:

1. An existing Harness to reuse.
2. A Harness without a named endpoint.
3. No AgentCore project yet.

Never add Slack behavior by editing generated agentcore/cdk source. JSON and the Harness directory remain authoritative for the AgentCore deployment. The Slack adapter is a separate standalone CDK app.

Step 1: Create or harden the Harness

If no project exists, have the user run the interactive wizard:

agentcore create

The user chooses the project name, model, region, tools, skills, and memory. Guide them to select a Harness, but do not guess those choices through a large non-interactive command.

For an existing project, reuse its Harness. Do not export it.

Before deployment, inspect app/<HARNESS>/harness.json and require:

• authorizerType is AWS_IAM;
• allowedTools explicitly names only intended tools;
• maxIterations, maxTokens, and timeoutSeconds are explicit;
• no shell, file_operations, wildcard, or unknown tool is exposed;
• the system prompt contains no channel-specific Slack formatting instructions.

For a tool-free starter Harness, an empty allowedTools list is appropriate. If tools are present, preserve their exact configured names. Use the local schema rather than copying a possibly stale example.

The generated adapter sends invocation limits of 10 iterations, 8000 tokens, and 240 seconds. Align the Harness-level limits with those values, or deliberately lower both the Harness and adapter values after reviewing the workload. Do not let a channel adapter silently request broader limits than the Harness security review approved.

Validate:

agentcore validate

Stop on validation errors.

Step 2: Deploy and pin a named endpoint

Deploy the AgentCore project:

agentcore deploy
agentcore status --type harness --json

Confirm the deployed Harness is READY. Then create or update a stable endpoint:

python <SKILL_DIR>/scripts/ensure_harness_endpoint.py \
  --project-root . \
  --harness-name <HARNESS_NAME> \
  --endpoint-name PROD

The helper reads the current target's Harness ID and deployed version, calls the AgentCore control plane, and waits until the endpoint reports READY with that liveVersion.

Do not infer serving state from harnessVersion alone. The adapter invokes the endpoint qualifier, so the endpoint's live version is the serving authority.

Step 3: Scaffold the Slack adapter

From the AgentCore project root:

python <SKILL_DIR>/scripts/scaffold_slack_adapter.py \
  --project-root . \
  --app-name "<CUSTOMER_APP_NAME>"

This creates slack-adapter/ and refuses to overwrite an existing directory. Review the generated files before deployment.

Run local checks:

cd slack-adapter
python -m venv .venv
.venv/bin/python -m pip install -r requirements-dev.txt
.venv/bin/python -m pytest -q

cd infra
npm install
npm run build
npm test

Run npm audit and report findings. Do not claim that CDK development-tool dependencies are packaged into the Python Lambdas.

Step 4: Create the Slack app without events

Read references/slack-setup-and-troubleshooting.md.

Create a Slack app from:

slack-adapter/slack-app-manifest.bootstrap.yml

The bootstrap manifest intentionally omits Event Subscriptions, breaking the request URL cycle. Install the app in the approved workspace, then collect:

• Slack team/workspace ID;
• bot user ID;
• signing secret;
• bot token beginning with xoxb-.

Treat the signing secret and bot token as secrets. Never put them in source, manifests, CDK context, logs, tickets, or chat.

Step 5: Deploy the adapter

Read the Harness ARN from the current project's deploy output or agentcore/.cli/deployed-state.json. Do not paste a remembered ARN.

Review the exact infrastructure change:

cd slack-adapter/infra
npm run cdk -- diff \
  -c harnessArn=<CURRENT_HARNESS_ARN> \
  -c harnessQualifier=PROD \
  -c allowedTeamId=<SLACK_TEAM_ID> \
  -c slackBotUserId=<SLACK_BOT_USER_ID>

Then deploy with the same context:

npm run cdk -- deploy \
  -c harnessArn=<CURRENT_HARNESS_ARN> \
  -c harnessQualifier=PROD \
  -c allowedTeamId=<SLACK_TEAM_ID> \
  -c slackBotUserId=<SLACK_BOT_USER_ID>

Review the CDK diff before confirming. The expected resources are:

• one HTTP API;
• two Lambda functions;
• one FIFO queue and one FIFO DLQ;
• three Secrets Manager secrets;
• narrowly scoped invoke, queue, and secret permissions.

Record stack outputs: SlackRequestUrl, SigningSecretArn, BotTokenSecretArn, and DeadLetterQueueUrl.

Step 6: Populate secrets

Use the Slack app's Basic Information and OAuth pages. Prefer the AWS Secrets Manager console or an approved secret-management workflow.

If using the CLI, read secrets without echo and pass shell variables rather than literal secret values in command history. Update:

• SigningSecretArn with the Slack signing secret;
• BotTokenSecretArn with the installed bot token.

Do not replace the generated session HMAC key after conversations begin. Rotating it changes all derived AgentCore actor and session IDs.

Step 7: Enable Event Subscriptions

Replace REPLACE_WITH_REQUEST_URL in:

slack-adapter/slack-app-manifest.yml

with the SlackRequestUrl stack output. Apply that manifest to the existing Slack app, or set the same values in Slack's Event Subscriptions UI.

The request URL must verify successfully. Subscribe only to:

• app_mention for channels;
• message.im for direct messages.

Invite the bot only to intended channels. In a channel, mention it on every turn, including follow-ups in a thread. Do not add message.channels merely to avoid mentions; that sends unrelated channel traffic to the app.

Step 8: Verify end to end

Run these acceptance checks:

1. Mention the bot in an approved channel.
2. Confirm one Slack message starts before the Harness answer completes.
3. Confirm that message grows and then stops, rather than creating one post per delta.
4. Ask a follow-up in the same thread and confirm the same AgentCore session is reused.
5. Send a DM and confirm streaming works there.
6. Inspect ingress and worker logs by Slack event_id; confirm prompt and response text are not logged.
7. Confirm the FIFO queue drains and the DLQ remains empty.
8. Confirm the worker invokes the intended endpoint qualifier and not an unqualified Harness version.

If streaming is unavailable, the sample falls back to ordinary chat.postMessage. Treat that as a compatibility result, not proof that native streaming worked.

Step 9: Hand off honestly

Report:

• project path, branch, and dirty state;
• Harness name, ARN, endpoint name, endpoint status, and live version;
• adapter stack name and request URL;
• local validation results;
• whether channel and DM tests passed;
• whether the reply used native Slack streaming or fallback posting;
• resources created and cleanup commands;
• that changes are committed or uncommitted.

Before production, use references/architecture-and-hardening.md to discuss durable idempotency, stream checkpoints, allowlists, monitoring, rate limits, secret rotation, data retention, concurrency, and incident recovery.

Cleanup

Delete the Slack adapter stack when it is no longer needed:

cd slack-adapter/infra
npm run cdk -- destroy \
  -c harnessArn=<CURRENT_HARNESS_ARN> \
  -c harnessQualifier=PROD \
  -c allowedTeamId=<SLACK_TEAM_ID>

Remove the Slack app or disable Event Subscriptions. Remove the Harness only when the user explicitly confirms it is not shared by other channels or applications.

Quick order

1. Obtain consent.
2. Inspect or create the Harness.
3. Harden and validate Harness configuration.
4. Deploy Harness and pin PROD.
5. Scaffold and test slack-adapter/.
6. Create and install the bootstrap Slack app.
7. Deploy the adapter.
8. Populate Slack secrets.
9. Apply the final manifest.
10. Verify channel, thread, DM, streaming, logs, queue, and endpoint version.
11. Report limitations and cleanup.