Add source DB option to Fill from DB (BRU-4473)

[DjamilaBaroudi]

Summary

• Adds a connection picker dropdown next to the "Fill from DB" button on the Columns tab so users can pull column schemas from a non-destination connection.
• For ingestr assets, the asset's source_connection is auto-suggested at the top of the menu with a source label.
• Selecting any entry forwards --connection <name> to bruin patch fill-columns-from-db (added upstream in bruin#2079).
• Default left-click on the button is unchanged — still fills from the destination connection.

Closes BRU-4473.

Motivation

Users cloning a source table to e.g. MSSQL want to copy the schema exactly (nullability, columns with nulls). Today "Fill from DB" always reads from the destination, so the workaround is editing pipeline.yml to swap destination → source, save, fill, swap back. This PR removes that workaround.

Files changed

• webview-ui/src/components/asset/columns/AssetColumns.vue — split button + Headless UI menu listing connections; matches the Validate split-button styling.
• webview-ui/src/App.vue — pass assetType and parameters props to AssetColumns.
• src/panels/BruinPanel.ts — read connection from payload and append --connection <name> to fill-columns flags.
• CHANGELOG.md, README.md, package.json — 0.80.2 bump.

Backwards compatibility

If a user is on a pre-#2079 bruin binary and clicks a connection from the menu, the CLI returns an unknown-flag error which is surfaced via the existing fill-columns-message error path. No version gate needed.

🤖 Generated with Claude Code

[greptile-apps]

Comments Outside Diff (1)

1. webview-ui/src/components/asset/columns/AssetColumns.vue, line 1163 (link)

   Connection list not scoped to the current environment

   bruin.getConnectionsList is dispatched without any environment hint, so the underlying bruin connections list -o json command runs without -env. The response may include connections from all environments or only the default one. If the user has a non-default environment selected and picks a connection that only exists there, the fill command will receive --environment <selected> --connection <name>, which could silently target the wrong connection. Consider passing the currently selected environment when requesting the list, or showing a tooltip indicating which environment the listed connections belong to.

   Prompt To Fix With AI

   This is a comment left during a code review.
   Path: webview-ui/src/components/asset/columns/AssetColumns.vue
   Line: 1163
   
   Comment:
   **Connection list not scoped to the current environment**
   
   `bruin.getConnectionsList` is dispatched without any environment hint, so the underlying `bruin connections list -o json` command runs without `-env`. The response may include connections from all environments or only the default one. If the user has a non-default environment selected and picks a connection that only exists there, the fill command will receive `--environment <selected> --connection <name>`, which could silently target the wrong connection. Consider passing the currently selected environment when requesting the list, or showing a tooltip indicating which environment the listed connections belong to.
   
   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
webview-ui/src/components/asset/columns/AssetColumns.vue:1163
**Connection list not scoped to the current environment**

`bruin.getConnectionsList` is dispatched without any environment hint, so the underlying `bruin connections list -o json` command runs without `-env`. The response may include connections from all environments or only the default one. If the user has a non-default environment selected and picks a connection that only exists there, the fill command will receive `--environment <selected> --connection <name>`, which could silently target the wrong connection. Consider passing the currently selected environment when requesting the list, or showing a tooltip indicating which environment the listed connections belong to.

### Issue 2 of 2
webview-ui/src/components/asset/columns/AssetColumns.vue:95-97
**"No connections found" flashes before the first response arrives**

`availableConnections` starts as an empty array and the `connections-list-message` response is asynchronous. On the first render of the menu, if the request hasn't completed yet, a non-ingestr asset (or an ingestr asset whose `source_connection` is absent) will immediately show "No connections found" until the response arrives. Adding a loading flag that is set to `true` in `onMounted` and cleared in `handleConnectionsList` (success or error) would prevent this flash.

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