fix(cli): prevent truncate helpers from overflowing at small widths

[Tamsi]

Summary

Locale.truncateLeft and Locale.truncateMiddle (packages/opencode/src/util/locale.ts) build their tail slice with str.slice(-keep). When keep is 0, str.slice(-0) evaluates to str.slice(0) and returns the entire string — so instead of truncating, the helper returns something longer than the input:

truncateLeft("src/components/very-long-file-name.tsx", 1)
// → "…src/components/very-long-file-name.tsx"  (39 chars for a width of 1)

truncateMiddle("src/components/very-long-file-name.tsx", 2)
// → "s…src/components/very-long-file-name.tsx"  (40 chars for a width of 2)

keep reaches 0 at maxLength 1 for both helpers, and at maxLength 2 for truncateMiddle.

These aren't purely theoretical widths — the TUI calls these helpers with dynamic widths that bottom out at 1, e.g. dialog-select.tsx:

{Locale.truncateMiddle(detail, Math.max(1, Math.min(76, dimensions().width - 12)))}

On a very narrow pane the "truncated" string is emitted at full length and blows out the layout it was supposed to fit.

Fix

Drop the tail explicitly when keep <= 0 (so the result is just head + ellipsis, or a lone ellipsis at width 1), leaving all larger-width behavior unchanged.

locale.ts is a shared upstream (OpenCode) file, so the edits are wrapped in kilocode_change markers per AGENTS.md, and bun run script/check-opencode-annotations.ts passes. The regression test lives under packages/opencode/test/kilocode/ (Kilo-specific test path).

Test plan

• Added packages/opencode/test/kilocode/locale.test.ts covering the length-1 / length-2 edges and asserting the output never exceeds maxLength.
• New tests pass with the fix (9 passed).
• Confirmed the tests fail on main without the fix (5 failed — e.g. truncateMiddle(long, 2) returned "s…src/components/very-long-file-name.tsx" instead of "s…").
• bun run script/check-opencode-annotations.ts → "All shared upstream changes are annotated with kilocode_change markers."

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

This update wraps the existing fix in locale.ts with kilocode_change markers and moves the regression test into packages/opencode/test/kilocode/ — housekeeping only, no logic changes. The import path (../../src/util/locale) still resolves correctly after the move. Markers are placed correctly around only the changed lines.

Note: No changeset was added yet. This still fixes a user-visible TUI overflow bug (truncateLeft/truncateMiddle emitting the full string instead of an ellipsis at very narrow widths), so per repo convention consider adding a patch changeset describing the fix from the user's perspective.

Files Reviewed (2 files)

• packages/opencode/src/util/locale.ts
• packages/opencode/test/kilocode/locale.test.ts

Previous Review Summary (commit b8b90ee)

Current summary above is authoritative. Previous snapshots are kept for context only.

Previous review (commit b8b90ee)

Status: No Issues Found | Recommendation: Merge

Note: No changeset was added. This fixes a user-visible TUI overflow bug (truncateLeft/truncateMiddle emitting the full string instead of an ellipsis at very narrow widths), so per repo convention consider adding a patch changeset describing the fix from the user's perspective.

Files Reviewed (2 files)

• packages/opencode/src/util/locale.ts
• packages/opencode/test/util/locale.test.ts

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_{Reviewed by claude-sonnet-5-20260630 · Input: 32 · Output: 6.6K · Cached: 627.5K}

_{Review guidance: REVIEW.md from base branch main}