[Noobear]

Summary

• paint xterm's opaque IME composition overlay with the cursor cell's effective ANSI background instead of the terminal-wide theme background
• resolve RGB, indexed palette, default, and inverse cell colors while preserving the existing mid-line tail masking behavior
• regenerate the canonical xterm patch and lockfile hash, and add unit plus Electron regression coverage for styled prompt rows

Why

The composition overlay intentionally stays opaque so committed cells hidden beneath it remain readable through the rendered row tail. On a prompt row with its own ANSI background, however, the overlay used the terminal theme background and produced a visible seam behind the active Korean preedit.

Validation

• pnpm install --frozen-lockfile --ignore-scripts
• 27 related renderer test files: 342 passed
• focused xterm IME tests on macOS arm64: 17 passed
• macOS arm64 Electron e2e: 3 passed
  • mid-line Korean tail remains readable
  • styled ANSI background matches the opaque overlay
  • end-of-row composition remains unchanged
• node config/scripts/regenerate-xterm-patches.mjs --check on macOS arm64
• pnpm typecheck:web
• targeted oxlint for the changed TypeScript tests/probe

[coderabbitai]

📝 Walkthrough

Walkthrough

The patch updates CompositionHelper to track deferred IME transactions, reconcile composition, input, and keypress data, and handle cancellation and disposal. CoreBrowserTerminal routes input through the helper and emits accepted-transaction events. Composition overlays now use opaque colors derived from the cursor cell and support trailing preedit positioning. Unit and end-to-end tests cover ANSI, inverse, indexed-color, and Korean preedit cases.

Merge Risk: 🟡 Moderate · up to 79fe4

An empty IME cancellation can leave the terminal composing state stuck, causing subsequent user input to be withheld instead of sent. The PR is not merge-ready until this bounded input-loss risk is fixed or explicitly accepted.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description explains the change, rationale, and validation, but it omits required template sections including Linked Issue, Visual Proof, and checklist confirmations.	Use the repository template headings, add a linked issue, provide visual proof or an explicit N/A reason, and complete the required testing and review checklists.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the terminal IME fix and the preservation of ANSI backgrounds under the preedit overlay.
Docstring Coverage	✅ Passed	Docstring check was indeterminate for this PR — some files could not be analyzed in time. Not blocking.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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[coderabbitai]

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

config/patches/xterm-src/@xterm__xterm@6.1.0-beta.287.src.patch (1)

342-348: 🎯 Functional Correctness | 🟠 Major | 🏗️ Heavy lift

Settle an empty compositionend for the active transaction.

If a composition starts and then ends with empty data before the textarea or selection changes, _compositionEndBelongsToCurrentTransaction stays false. The deferred callback then returns without clearing _isComposing. Later input events without a keydown are stored in _compositionInputData and are not sent. Treat this current-transaction case as cancellation after deferred inspection.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro Plus

Run ID: b2d16bf0-8970-41ec-807c-638f63ee822f

📥 Commits

Reviewing files that changed from the base of the PR and between afd76a4 and 79fe456.

⛔ Files ignored due to path filters (1)

• pnpm-lock.yaml is excluded by !**/pnpm-lock.yaml

📒 Files selected for processing (5)

• config/patches/@xterm__xterm@6.1.0-beta.287.patch
• config/patches/xterm-src/@xterm__xterm@6.1.0-beta.287.src.patch
• src/renderer/src/components/terminal-pane/terminal-ime-xterm-trailing-preedit-occlusion.test.ts
• tests/e2e/terminal-ime-midline-occlusion-probe.ts
• tests/e2e/terminal-korean-midline-preedit-occlusion.spec.ts

Included review availability: Your plan provides up to 10 included reviews per hour; 9 remain after this review.