Open labs/lab07-first-worker/worker/src/index.js and read handleGithubChatops(). Key behaviors:

• Signature verification: GitHub signs every request with HMAC-SHA256 using your webhook secret. The Worker reads X-Hub-Signature-256 and recomputes the digest over the raw request body. Requests with missing or mismatched signatures are rejected with HTTP 401.
• Loop protection: The Worker drops any comment whose body starts with [eplabs:result] (its own replies) or that was authored by a bot user (sender.type === "Bot"). Duplicate X-GitHub-Delivery IDs within 600 seconds are also rejected.
• Prefix gate: The comment body must start with @${STUDENT_SLOT} (the student’s slot, e.g. @alpha). The Worker strips the prefix before passing the remainder to EmojiChef.
• Decode and dispatch: EmojiChefQuick.decode() converts the emoji string to ASCII. The first whitespace-delimited token is the command name; remaining tokens are args.
• Command vocabulary: status, reboot, capture, list, ping, exec, fetch, and HSC are valid commands. Unknown commands return 422 with a list of known commands.
• Result post: Uses the GitHub Issues API to post a reply on the same issue. The reply body begins with [eplabs:result] @${STUDENT_SLOT}.

Also open labs/lab07-first-worker/worker/src/emojichef.js and read the EmojiChefQuick class. The encoder and decoder are symmetric: each ASCII byte becomes 8 bits, the bitstream is cut into 6-bit windows, and each window value n maps to codepoint 0x1F345 + n.

Use the live widget below to encode and decode strings. Enter status, HSC, or reboot and copy the emoji output.

Verify the known test vectors with Node if preferred:

cd courses/engagement-platform-labs/labs/lab07-first-worker/worker
node -e "
const BASE = 0x1F345;
const encode = t => [...t].reduce((b, c) => b + c.charCodeAt(0).toString(2).padStart(8,'0'), '')
    .match(/.{6}/g).map(s => String.fromCodePoint(BASE + parseInt(s,2))).join('');
const decode = e => [...e].map(c => (c.codePointAt(0) - BASE).toString(2).padStart(6,'0')).join('')
    .match(/.{8}/g).map(s => String.fromCharCode(parseInt(s,2))).join('');
['HSC','status','reboot'].forEach(t => console.log(t, '->', encode(t), '-> decoded:', decode(encode(t))));
"

Expected output:

HSC -> 🍗🍊🍒🍈 -> decoded: HSC
status -> 🥘🥫🥩🌯🥙🥘 -> decoded: status
reboot -> 🍱🥤🥩🥓🥨🥯🌯 -> decoded: reboot

The full set of test vectors is in test-vectors.txt in this lab directory.

The Worker reads GITHUB_OWNER, GITHUB_REPO, and GITHUB_ISSUE_NUMBER from its [vars] to know where to post replies. Issue #1 in your repo is the canonical command queue for this lab.

1. Go to your workshop GitHub repo (fork of epl-student-starter or a fresh repo). If you do not have one, create a new empty public repo now.

2. Open the Issues tab and click New issue.

3. Title it EPL Command Queue (or anything recognizable). Click Submit new issue.

4. Note the issue number in the URL. It should be #1 if this is the first issue in the repo.

Note your values for the next step:

GITHUB_OWNER=<your-github-username>
GITHUB_REPO=<your-repo-name>
GITHUB_ISSUE_NUMBER=1

The Worker needs a token to post replies. Generate a fine-grained token scoped to Issues on this one repo only. See github-issue-chatops-setup.md in this lab directory for the full click-by-click walkthrough; the abbreviated path is:

1. GitHub Settings (avatar menu, top right).
2. Developer settings (bottom of the left sidebar).
3. Personal access tokens > Fine-grained tokens > Generate new token.
4. Token name: eplabs-chatops-<your-slot>.
5. Expiration: 30 days (or workshop duration).
6. Repository access: “Only select repositories” > choose your workshop repo.
7. Permissions > Repository permissions > Issues: set to Read and write.
8. Leave all other permissions at their defaults (no access).
9. Click Generate token and copy the token immediately (you will not see it again).

Keep the token value; you will need it in the next step.

Generate a random webhook secret:

openssl rand -hex 32
# or:
python3 -c 'import secrets; print(secrets.token_hex(32))'

Copy the output. This is your GITHUB_WEBHOOK_SECRET. Store it somewhere safe for this lab session. You will paste it into both the Worker and the GitHub webhook configuration.

Set the secrets:

cd courses/engagement-platform-labs/labs/lab07-first-worker/worker

npx wrangler secret put GITHUB_WEBHOOK_SECRET
# paste the 64-char hex string at the prompt

npx wrangler secret put GITHUB_TOKEN
# paste the fine-grained PAT from step 4

Open worker/wrangler.toml and add the [vars] entries for your repo:

[vars]
# ... existing vars ...
GITHUB_OWNER = "your-github-username"
GITHUB_REPO = "your-repo-name"
GITHUB_ISSUE_NUMBER = "1"
STUDENT_SLOT = "alpha"

Replace alpha with your assigned slot (e.g. bravo, charlie).

Redeploy the Worker so the new vars and secrets are active:

npx wrangler deploy

In your GitHub repository:

1. Go to Settings > Webhooks > Add webhook.
2. Payload URL: https://api.${DOMAIN}/v1/chatops/github (substitute your actual domain).
3. Content type: application/json.
4. Secret: paste the hex string you generated in step 5.
5. Under Which events would you like to trigger this webhook? select “Let me select individual events”. Uncheck Pushes, then check Issue comments only.
6. Make sure Active is checked.
7. Click Add webhook.

GitHub immediately sends a ping event. Open Recent Deliveries on the webhook settings page. You should see the ping with HTTP 204 (the Worker ignores pings) or HTTP 401 (bad secret: recheck the hex you pasted).

See github-issue-chatops-setup.md in this lab directory for the full walkthrough including screenshots.

Start tailing Worker logs in a terminal:

cd courses/engagement-platform-labs/labs/lab07-first-worker/worker
npx wrangler tail --format pretty

In a second terminal (or a browser), post a comment on your issue #1:

@alpha 🥘🥫🥩🌯🥙🥘

Replace @alpha with your actual STUDENT_SLOT value.

In the wrangler tail output you should see a log entry showing:

decoded: "status"   job_id: <uuid>   slot: alpha

The comment body 🥘🥫🥩🌯🥙🥘 decodes to the ASCII string status.

You can also post the comment via the GitHub API:

curl -s -X POST \
  -H "Authorization: Bearer ${GITHUB_TOKEN}" \
  -H "Accept: application/vnd.github+json" \
  "https://api.github.com/repos/${GITHUB_OWNER}/${GITHUB_REPO}/issues/${GITHUB_ISSUE_NUMBER}/comments" \
  -d '{"body":"@alpha 🥘🥫🥩🌯🥙🥘"}'

(Replace the emoji unicode escapes with the actual emoji string 🥘🥫🥩🌯🥙🥘 when typing in a shell that supports it.)

Reload your GitHub issue page. The Worker should have posted a reply comment whose body starts with:

[eplabs:result] @alpha status: queued, job_id: <uuid>

Confirm the job is also in KV:

JOB_ID="paste-job-id-here"
curl -s "https://api.${DOMAIN}/v1/jobs/${JOB_ID}" | jq .

Expected:

{
  "job_id": "...",
  "device_id": "broadcast",
  "command": "status",
  "params": { "args": [], "raw": "status" },
  "status": "queued",
  "created_at": "...",
  "timeout": 60,
  "source": "github_chatops",
  "author": "<your-github-username>"
}

Try all three known test vectors from issue #1:

Each should produce a separate [eplabs:result] reply and a KV job entry.

chmod +x courses/engagement-platform-labs/labs/lab11-chatops-emojichef/validate.sh
export DOMAIN="<your-domain>"
# GITHUB_TOKEN, GITHUB_OWNER, GITHUB_REPO, GITHUB_ISSUE_NUMBER, STUDENT_SLOT
# are read from the environment or from wrangler.toml [vars]
courses/engagement-platform-labs/labs/lab11-chatops-emojichef/validate.sh

The script posts a fresh @<slot> 🥘🥫🥩🌯🥙🥘 comment using your GITHUB_TOKEN, then polls the issue for the bot’s reply for up to 30 seconds. It asserts that the reply body starts with [eplabs:result] @<slot> and that the decoded command is status.