[hetaoBackend]

Change

Related to #265. When a terminal delivers an unframed multiline text chunk, StdinBuffer splits its CR bytes into Enter key events. Replaying three CR/CRLF-separated lines through ProcessTerminal and the product Editor reproduced three unintended submissions before this change.

Route plain-text chunks containing an internal line ending through the existing paste event before key splitting. The editor then normalizes line endings and tabs and preserves large-paste folding. Bracketed paste, standalone Enter, text followed only by a final Enter, and control sequences keep their existing paths. No timing heuristic or third-party source change is introduced.

This is a bounded fallback: unframed input split into line-sized or character-sized chunks remains indistinguishable from typing. Conversely, multiple typed lines coalesced into one chunk are treated as a paste. The issue does not identify the host terminal or include raw input bytes, so the reporter's exact WSL cause remains unconfirmed. The issue should remain open for host-terminal confirmation.

Validation

• PASS: pnpm verify, full profile on clean commit cd9fbe785cab6d033d70615eb6d8fbcf253e0f46, macOS arm64 / Node 26.4.0 (14 applicable gates).
• PASS: focused editor/input/shortcut regression suite (127 tests), plus the completed new terminal paste suite (9 tests). The CR and CRLF regressions failed before the fix with three separate submissions.
• PASS: built dist/cli.js in macOS PTYs, regular and fullscreen modes: unframed CRLF multiline draft, fragmented bracketed paste, /help submitted with ordinary Enter, and paste-mode enable/disable output. xterm-headless readback verified draft lines and the resulting Help panel. Synthetic temporary data; network blocked.
• Performance: basic, covered by the automatic PR benchmark; this change is not a performance optimization or model-streaming change.
• NOT RUN: real WSL Ubuntu 24 / Shift+Insert clipboard acceptance, native Windows, Linux terminal acceptance, and live providers. PTY byte injection is not a physical clipboard test. Remote CI status is reported separately.

Publication and contribution checks

• Existing licenses and provenance notices are preserved; no imported code or license changes.
• No credentials, account data, real user content, internal source history or private review material is included.
• The new regression file was reviewed, declared in test/vitest-suites.json, and included in regenerated release/public-source.json.
• Engine local-change records document the behavior and ambiguity boundary. No shared English/Chinese user documentation changed.

Maintainer handoff

Publication scope or license changes: none.

Shared-source port: pending.

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