Local workspace CSV opens as raw text, while Open with Codex opens a spreadsheet canvas

What version of the Codex App are you using?

26.715.72359 (build 5718)

What platform is your computer?

macOS 26.5.2 (build 25F84), Darwin 25.5.0, Apple Silicon (arm64)

What issue are you seeing?

For the same valid local .csv file, Codex App selects two incompatible default viewers depending on how the file is opened:

• Clicking the CSV in the workspace Files browser opens raw comma-separated source in the text/source editor.
• Opening that same file through macOS Open with → Codex opens the spreadsheet experience (CSV import controls, A1/name box, formula bar, and grid canvas).

The second route successfully parses the file, so malformed CSV is not a sufficient explanation. This is confusing because the primary workspace-file action does not expose an obvious Open as spreadsheet / rendered-view action.

No private filenames, paths, CSV rows, screenshots, recordings, or session content are included in this report.

What steps can reproduce the bug?

1. Create a small local CSV, for example:

``csv
item,amount
alpha,1
beta,2
``

1. Place it in a local Codex workspace.
2. In the workspace Files browser, click the CSV.
3. Observe that it opens as raw source/text.
4. In Finder, choose Open with → Codex for the same CSV.
5. Observe that Codex opens a spreadsheet-style import/grid view instead.

Observed on the same file and app build.

What is the expected behavior?

Please align or document the intended behavior. If CSV files have a spreadsheet viewer, the primary Files-browser click should open it, or the source view should offer a clear Open as spreadsheet action. An explicit View source choice can remain available for users who want raw CSV text.

Diagnostic note

Best-effort static inspection of the shipped app resources shows:

• CSV is recognized as a spreadsheet artifact/import kind.
• The spreadsheet path parses CSV through the workbook CSV importer.
• Explicit workspace/file-manager opens appear to take a generic file route before artifact dispatch.

That is consistent with the observed entry-path split and suggests the regression seam is the resolved viewer target for text/csv across Files browser click versus OS open event.

A focused route-level test could assert that both origins resolve to the same default rendered target, while an explicit View source action continues to resolve to the text editor.

Additional information

• Reproduction was visually captured locally on the stated build.
• Workaround: use Open with → Codex when the spreadsheet canvas is needed.
• Related but not duplicate: #26964 covers a Mac remote client previewing a CSV on a Windows host; #31749 covers blank .xlsx workbook rendering.