fix(arg-parsing): split arguments by all whitespace

[sentry]

This PR addresses CLI-1HT, where users (especially AI agents) encountered ValidationError: Invalid Event ID: contains a space. when providing multiple event IDs as a single, space-separated argument.

The root cause was that the splitNewlineArg utility function, intended to expand multiple IDs from a single string, only split on newline characters (\n). This meant that space-separated IDs were treated as a single, invalid ID.

This fix modifies splitNewlineArg in src/lib/arg-parsing.ts to split on all whitespace (/\s+/) instead of just newlines. This ensures that event IDs provided with spaces, tabs, or newlines are correctly parsed into individual arguments, preventing validation errors.

Fixes CLI-1HT

_{Comment @sentry <feedback> on this PR to have Autofix iterate on the changes.}

[github-actions]

PR Preview Action v1.8.1
🚀 View preview at https://cli.sentry.dev/_preview/pr-1268/
Built to branch gh-pages at 2026-07-17 23:11 UTC. Preview will be ready when the GitHub Pages deployment is complete.

[sentry]

Bug: The change to split arguments on any whitespace (/\s+/) in splitNewlineArg will incorrectly break up project display names containing spaces, like "org/My Project".
_{Severity: HIGH}

Suggested Fix

The fix should be more targeted to only apply to the arguments that are expected to be lists (like event IDs), while preserving the original behavior for arguments that could be project display names. This might involve making the splitting behavior conditional or applying it at a different stage of parsing, after project arguments have already been identified and handled. For example, only apply the whitespace split within the event view command's argument handling, not globally in splitNewlineArg.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent. Verify if this is a real issue. If it is, propose a fix; if not, explain why it's
not valid.

Location: src/lib/arg-parsing.ts#L1247

Potential issue: The function `splitNewlineArg` was changed to split arguments on any
whitespace (`/\s+/`) to support space-separated IDs. However, this introduces a
regression. The CLI supports project display names with spaces (e.g., `"org/My
Project"`), and has logic to handle them as a single argument. When such a display name
is passed as a single string, which is a common scenario for programmatic callers like
AI agents, the new logic will incorrectly split it into multiple arguments (e.g.,
`["org/My", "Project"]`). This breaks downstream parsing logic which expects a single
project argument, causing command failures.

Also affects:

• src/commands/event/view.ts:179

_{Did we get this right? 👍 / 👎 to inform future reviews.}

[github-actions]

Codecov Results 📊

✅ Patch coverage is 100.00%. Project has 5479 uncovered lines.
✅ Project coverage is 81.67%. Comparing base (base) to head (head).

Coverage diff

@@            Coverage Diff             @@
##          main       #PR       +/-##
==========================================
+ Coverage    81.67%    81.67%        —%
==========================================
  Files          426       426         —
  Lines        29896     29896         —
  Branches     19420     19420         —
==========================================
+ Hits         24416     24417        +1
- Misses        5480      5479        -1
- Partials      2035      2034        -1

---

Generated by Codecov Action