feat: expose slack agent configuration page via posthog code settings

[posthog]

Summary

• Adds a Slack tab to the settings sidebar (between GitHub and Signals) using the Phosphor SlackLogo icon.
• The tab renders a Slack integration page with a short description and a Manage in PostHog Web button that opens the project-level Slack integration page in the user's active PostHog cloud region (/project/{projectId}/settings/project-posthog-code#integration-posthog-code-slack).
• Until Slack is configurable directly from PostHog Code, this gives users a discoverable entry point — they were previously hunting through PostHog Web with no link from the app.

Test plan

• Open Settings → Slack and verify the title Slack integration, description copy, and Manage in PostHog Web button render.
• Click the button while signed in and confirm it opens the correct project Slack integration URL in the default browser (US/EU regions both honored via getPostHogUrl).
• Sign out (or clear projectId) and confirm the button is disabled rather than opening a broken URL.

---

Created with PostHog Code

[greptile-apps]

Comments Outside Diff (2)

1. apps/code/src/renderer/features/settings/components/sections/SlackSettings.tsx, line 24-35 (link)

   Disabled button with no explanation for the user — per the project convention of disabling with a tooltip rather than silently, the button should carry a tooltip when projectId is missing so users know why nothing happens when they hover it.

   Rule Used: When disabling UI components based on certain cond... (source)

   Learned From
   PostHog/posthog#32600

   Prompt To Fix With AI

   This is a comment left during a code review.
   Path: apps/code/src/renderer/features/settings/components/sections/SlackSettings.tsx
   Line: 24-35
   
   Comment:
   Disabled button with no explanation for the user — per the project convention of disabling with a tooltip rather than silently, the button should carry a tooltip when `projectId` is missing so users know why nothing happens when they hover it.
   
   
   
   **Rule Used:** When disabling UI components based on certain cond... ([source](https://app.greptile.com/review/custom-context?memory=788b3d9d-2e6e-41e7-a14c-553ff0b3d06c))
   
   **Learned From**
   [PostHog/posthog#32600](https://github.com/PostHog/posthog/pull/32600)
   
   How can I resolve this? If you propose a fix, please make it concise.

   Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!

2. apps/code/src/renderer/features/settings/components/sections/SlackSettings.tsx, line 2 (link)

   openUrlInBrowser is a generic OS utility but is imported from a GitHub-specific integration hook. This creates an unnecessary coupling between the Slack settings component and the GitHub integration module. The function should be sourced from a shared utilities location.

   Prompt To Fix With AI

   This is a comment left during a code review.
   Path: apps/code/src/renderer/features/settings/components/sections/SlackSettings.tsx
   Line: 2
   
   Comment:
   `openUrlInBrowser` is a generic OS utility but is imported from a GitHub-specific integration hook. This creates an unnecessary coupling between the Slack settings component and the GitHub integration module. The function should be sourced from a shared utilities location.
   
   
   
   How can I resolve this? If you propose a fix, please make it concise.

Prompt To Fix All With AI

Fix the following 2 code review issues. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 2
apps/code/src/renderer/features/settings/components/sections/SlackSettings.tsx:24-35
Disabled button with no explanation for the user — per the project convention of disabling with a tooltip rather than silently, the button should carry a tooltip when `projectId` is missing so users know why nothing happens when they hover it.

```suggestion
      <Flex>
        <Tooltip
          content="Sign in to a project to manage Slack settings"
          hidden={!!slackSettingsUrl}
        >
          <Button
            size="1"
            disabled={!slackSettingsUrl}
            onClick={() => {
              if (slackSettingsUrl) void openUrlInBrowser(slackSettingsUrl);
            }}
          >
            <ArrowSquareOutIcon size={12} />
            Manage in PostHog Web
          </Button>
        </Tooltip>
      </Flex>
```

### Issue 2 of 2
apps/code/src/renderer/features/settings/components/sections/SlackSettings.tsx:2
`openUrlInBrowser` is a generic OS utility but is imported from a GitHub-specific integration hook. This creates an unnecessary coupling between the Slack settings component and the GitHub integration module. The function should be sourced from a shared utilities location.

```suggestion
import { openUrlInBrowser } from "@features/integrations/utils/browser";
```

_{Reviews (1): Last reviewed commit: "feat: add Slack tab to settings linking ..." | Re-trigger Greptile}