#21147: feat(slack): support chat:write.customize for custom bot name/avatar

## Summary Closes #21133 When `ui.assistant.name` is configured and the bot token includes the `chat:write.customize` scope, OpenClaw now passes `username` and `icon_emoji` (or `icon_url`) to `chat.postMessage` so the bot appears in Slack with the configured assistant identity instead of the default app name. ## Changes ### `src/slack/monitor/replies.ts` - Added optional `identity?: SlackSendIdentity` parameter to `deliverReplies` - Forwarded it to both `sendMessageSlack` call sites (text and media paths) ### `src/slack/monitor/message-handler/dispatch.ts` - Added `buildSlackCustomIdentity(cfg, agentId)` helper that reads `ui.assistant.name` / `ui.assistant.avatar` (with per-agent identity fallback via `resolveAgentIdentity`) - Resolves identity once at start of `dispatchPreparedSlackMessage` and passes it through `deliverNormally` and the inline `deliverReplies` call - The lower-level `send.ts` already had `chat:write.customize` scope-error fallback (retries without custom identity if scope is absent) ### `skills/slack/SKILL.md` - Added new **Custom bot name and avatar (`chat:write.customize`)** section - Documents what it does, how to add the scope in api.slack.com, and how to configure `ui.assistant.name` / `ui.assistant.avatar` in openclaw.json ## Behavior - **When `ui.assistant.name` is set**: Slack messages from the bot show the configured name and `:robot_face:` emoji (or `icon_url` if avatar is an `https://` URL) - **When scope is absent**: Message is silently retried without custom identity — no error, no breakage - **When no name is configured**: Identity customization is skipped entirely ## Testing - No name configured → identity is `undefined` → `sendMessageSlack` called without identity → no change in behavior ✅ - Name configured, scope present → `username` + `icon_emoji`/`icon_url` sent ✅ - Name configured, scope absent → Slack returns `missing_scope` → `isSlackCustomizeScopeError` detects it → retry without identity → message delivered ✅ <!-- greptile_comment --> <h3>Greptile Summary</h3> Adds support for `chat:write.customize` scope to customize bot name and avatar in Slack messages. When `ui.assistant.name` is configured, the bot posts with custom identity (name + emoji/avatar) instead of default app name. Implementation includes graceful fallback when scope is missing - messages retry without custom identity on scope errors. <h3>Confidence Score: 5/5</h3> - This PR is safe to merge with minimal risk - Clean implementation with proper error handling, graceful fallback for missing scope, backward compatibility, clear documentation, and follows existing patterns in the codebase - No files require special attention _{Last reviewed commit: e203f73} <!-- greptile_other_comments_section --> _{(2/5) Greptile learns from your feedback when you react with thumbs up/down!} <!-- /greptile_comment -->