[Performance] Optimize linesToColumns in string utilities

[gonzaloriestra]

WHY are these changes introduced?

The linesToColumns utility function in packages/cli-kit is used to format CLI output into aligned columns. The previous implementation was inefficient because it:

1. Called unstyled(row).length twice for every cell (once for width calculation and once for padding). Since unstyled uses regex to strip ANSI escape codes, this is relatively expensive.
2. Performed multiple redundant O(Cols * Rows) array mappings to calculate max widths and row lengths.

WHAT is this pull request doing?

This PR optimizes linesToColumns by:

• Refactoring the column width calculation to use a single pass over the data.
• Caching unstyled lengths in an intermediate structure, reducing calls to the expensive unstyled utility by 50%.
• Eliminating redundant array mappings and intermediate array creations.

How to test your changes?

Run the following command to verify that the string utility tests still pass:
pnpm --filter @shopify/cli-kit vitest run src/public/common/string.test.ts

Duplicate check

Query: gh pr list --repo Shopify/cli --state all --limit 200 --search 'label:"Jules" "Performance" in:title' --json number,title,state,url,body,files
Fallback: git log --grep="\[Performance\]" --oneline

Closest prior PRs:

1. 9d50d23b6 [Performance] Optimize crypto utility functions: Optimized crypto helpers but didn't touch string utilities.
2. 024fbcaf5 [Performance] Optimize Liquid template rendering: Optimized template rendering logic.
3. a1c7666c9 [Performance] Optimize CLI startup and project discovery: Optimized project discovery and file system loading.

This PR is meaningfully different because it targets core string formatting logic in packages/cli-kit/src/public/common/string.ts, which was not addressed in previous performance PRs.

Checklist

• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've considered possible documentation changes
• I've considered analytics changes to measure impact
• The change is user-facing — I've identified the correct bump type (patch) and added a changeset with pnpm changeset add (Note: internal optimization, skipped changeset as per standard performance task scope)

---

PR created automatically by Jules for task 6574077092894988872 started by @gonzaloriestra

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[github-actions]

Differences in type declarations

We detected differences in the type declarations generated by Typescript for this branch compared to the baseline ('main' branch). Please, review them to ensure they are backward-compatible. Here are some important things to keep in mind:

• Some seemingly private modules might be re-exported through public modules.
• If the branch is behind main you might see odd diffs, rebase main into this branch.

New type declarations

We found no new type declarations in this PR

Existing type declarations

packages/cli-kit/dist/public/node/hooks/postrun.d.ts

@@ -1,3 +1,7 @@
+/**
+ * Postrun hook — uses dynamic imports to avoid loading heavy modules (base-command, analytics)
+ * at module evaluation time. These are only needed after the command has already finished.
+ */
 import { Hook } from '@oclif/core';
 /**
  * Check if post run hook has completed.
@@ -5,21 +9,6 @@ import { Hook } from '@oclif/core';
  * @returns Whether post run hook has completed.
  */
 export declare function postRunHookHasCompleted(): boolean;
-/**
- * Wait for the postrun hook to finish (so auto-upgrade has a chance to run) and then
- * tree-kill the current process tree before exiting.
- *
- * Long-running interactive commands like  need this when the user terminates
- * the command via  or Ctrl+C. The dev sub-processes such as servers and watchers keep
- * the event loop alive, so even after oclif's postrun hook completes the node process
- * won't exit on its own and we have to  the process tree. We must not do that
- * before the postrun hook has actually finished running auto-upgrade, otherwise we would
- * kill the upgrade mid-way while  is still running.
- *
- * The flag  is flipped at the very end of the hook after
- *  resolves, so polling it here is safe.
- */
-export declare function waitForPostRunHookAndExit(): void;
 export declare const hook: Hook.Postrun;
 /**
  * Auto-upgrades the CLI after a command completes, if a newer version is available.

packages/cli-kit/dist/private/node/ui/components/AutocompletePrompt.d.ts

@@ -20,13 +20,6 @@ export interface AutocompletePromptProps<T> {
     abortSignal?: AbortSignal;
     infoMessage?: InfoMessageProps['message'];
     groupOrder?: string[];
-    /**
-     * Throttle window in milliseconds applied to the search callback. Defaults to 400ms,
-     * which is appropriate for remote/paginated backends. In-memory consumers (where the
-     * search callback resolves synchronously) can pass 0 for instant filtering on every
-     * keystroke.
-     */
-    searchDebounceMs?: number;
 }
-declare function AutocompletePrompt<T>({ message, choices, infoTable, onSubmit, search, hasMorePages: initialHasMorePages, abortSignal, infoMessage, groupOrder, searchDebounceMs, }: React.PropsWithChildren<AutocompletePromptProps<T>>): ReactElement | null;
+declare function AutocompletePrompt<T>({ message, choices, infoTable, onSubmit, search, hasMorePages: initialHasMorePages, abortSignal, infoMessage, groupOrder, }: React.PropsWithChildren<AutocompletePromptProps<T>>): ReactElement | null;
 export { AutocompletePrompt };
\ No newline at end of file

[github-actions]

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