docs(add-github): document bot account, userName, sender policy, and wiring

Update SKILL.md with tested setup: dedicated bot account prerequisite,
GITHUB_BOT_USERNAME env var for @-mention detection, private vs public
repo sender policy guidance, member registration for strict mode,
per-thread session mode, and wiring example.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.claude/skills/add-github/SKILL.md

@@ -7,6 +7,10 @@ description: Add GitHub channel integration via Chat SDK. PR and issue comment t
 
 Adds GitHub support via the Chat SDK bridge. The agent participates in PR and issue comment threads.
 
+## Prerequisites
+
+You need a **dedicated GitHub bot account** (not your personal account). The adapter uses this account to post replies and filters out its own messages to avoid loops. Create a free GitHub account for your bot (e.g. `my-org-bot`), then invite it as a collaborator with write access to the repos you want monitored.
+
 ## Install
 
 NanoClaw doesn't ship channels in trunk. This skill copies the GitHub adapter in from the `channels` branch.
@@ -55,40 +59,90 @@ pnpm run build
 
 ## Credentials
 
-> 1. Go to [GitHub Settings > Developer Settings > Personal Access Tokens](https://github.com/settings/tokens)
+### 1. Create a Personal Access Token for the bot account
-> 2. Create a **Fine-grained token** with:
->    - Repository access: select the repos you want the bot to monitor
->    - Permissions: **Pull requests** (Read & Write), **Issues** (Read & Write)
-> 3. Copy the token
-> 4. Set up a webhook on your repo(s):
->    - Go to **Settings** > **Webhooks** > **Add webhook**
->    - Payload URL: `https://your-domain/webhook/github`
->    - Content type: `application/json`
->    - Secret: generate a random string
->    - Events: select **Issue comments**, **Pull request review comments**
 
-### Configure environment
+Log in as your **bot account**, then:
+
+1. Go to [Settings > Developer Settings > Personal Access Tokens](https://github.com/settings/tokens)
+2. Create a **Fine-grained token** with:
+   - Repository access: select the repos you want the bot to monitor
+   - Permissions: **Pull requests** (Read & Write), **Issues** (Read & Write)
+3. Copy the token
+
+### 2. Set up a webhook on each repo
+
+On each repo (logged in as the repo owner/admin):
+
+1. Go to **Settings** > **Webhooks** > **Add webhook**
+2. Payload URL: `https://your-domain/webhook/github` (the shared webhook server, default port 3000)
+3. Content type: `application/json`
+4. Secret: generate a random string (e.g. `openssl rand -hex 20`)
+5. Events: select **Issue comments** and **Pull request review comments**
+
+### 3. Configure environment
 
 Add to `.env`:
 
 ```bash
 GITHUB_TOKEN=github_pat_...
 GITHUB_WEBHOOK_SECRET=your-webhook-secret
+GITHUB_BOT_USERNAME=your-bot-username
 ```
 
+`GITHUB_BOT_USERNAME` must match the bot account's GitHub username exactly. This is used for @-mention detection — the agent responds when someone writes `@your-bot-username` in a PR or issue comment.
+
 Sync to container: `mkdir -p data/env && cp .env data/env/env`
 
+## Wiring
+
+Ask the user: **Is this a private or public repo?**
+
+- **Private repo** — use `unknown_sender_policy: 'public'`. Only collaborators can comment anyway, so it's safe to let all comments through.
+- **Public repo** — use `unknown_sender_policy: 'strict'`. Only registered members can trigger the agent, preventing strangers from consuming agent resources. Add trusted collaborators as members (see below).
+
+Run `/manage-channels` to wire the GitHub channel to an agent group, or insert manually:
+
+```sql
+-- Create messaging group (one per repo)
+INSERT INTO messaging_groups (id, channel_type, platform_id, name, is_group, unknown_sender_policy, created_at)
+VALUES ('mg-github-myrepo', 'github', 'github:owner/repo', 'owner/repo', 1, '<policy>', datetime('now'));
+
+-- Wire to agent group
+INSERT INTO messaging_group_agents (id, messaging_group_id, agent_group_id, trigger_rules, response_scope, session_mode, priority, created_at)
+VALUES ('mga-github-myrepo', 'mg-github-myrepo', '<your-agent-group-id>', '', 'all', 'per-thread', 10, datetime('now'));
+```
+
+Replace `<policy>` with `public` or `strict` based on the user's choice above.
+
+### Adding members (for strict mode)
+
+When using `strict`, add each GitHub user who should be able to trigger the agent:
+
+```sql
+-- Add user (kind = 'github', id = 'github:<numeric-user-id>')
+INSERT OR IGNORE INTO users (id, kind, display_name, created_at)
+VALUES ('github:<user-id>', 'github', '<username>', datetime('now'));
+
+-- Grant membership to the agent group
+INSERT OR IGNORE INTO agent_group_members (user_id, agent_group_id)
+VALUES ('github:<user-id>', '<agent-group-id>');
+```
+
+To find a GitHub user's numeric ID: `gh api users/<username> --jq .id`
+
+Use `per-thread` session mode so each PR/issue gets its own agent session.
+
 ## Next Steps
 
 If you're in the middle of `/setup`, return to the setup flow now.
 
-Otherwise, run `/manage-channels` to wire this channel to an agent group.
+Otherwise, restart the service (`systemctl --user restart nanoclaw` or `launchctl kickstart -k gui/$(id -u)/com.nanoclaw`) to pick up the new channel.
 
 ## Channel Info
 
 - **type**: `github`
 - **terminology**: GitHub has "repositories" containing "pull requests" and "issues." Each PR or issue comment thread is a separate conversation.
-- **how-to-find-id**: The platform ID is `owner/repo` (e.g. `acme/backend`). Each PR/issue becomes its own thread automatically.
+- **how-to-find-id**: The platform ID is `github:owner/repo` (e.g. `github:acme/backend`). Each PR/issue becomes its own thread automatically.
 - **supports-threads**: yes (PR and issue comment threads are native conversations)
-- **typical-use**: Webhook/notification — the agent receives PR and issue events and responds in comment threads
+- **typical-use**: Webhook-driven — the agent receives PR and issue comment events and responds in comment threads when @-mentioned. After the first mention, the thread is subscribed and the agent responds to all follow-up comments.
-- **default-isolation**: Typically shares a session with a chat channel (e.g. Slack) so the agent can summarize PRs and respond to reviews in the same context. Use a separate agent group if the repo contains sensitive code that other channels shouldn't access.
+- **default-isolation**: Use `per-thread` session mode. Each PR or issue gets its own isolated agent session. Typically wire to a dedicated agent group if the repo contains sensitive code.