fix(web): preserve shifted terminal input

[cedi]

Problem

Fixes #5276

Neovim enables Kitty keyboard disambiguation when it starts in the built-in terminal. Pressing Shift+; should produce : and open the Neovim command line, but T3 Code encoded it as ESC[59;2u, so Neovim handled it as ; instead.

This appeared specific to Neovim because a regular shell uses the legacy keyboard path, where the browser-provided : text was already emitted correctly.

Root cause

The web Ghostty bridge passed 0 to ghostty_key_event_set_consumed_mods for every key event. That told the Kitty encoder that Shift was still an effective modifier even when the browser had already consumed Shift to translate the layout base character ; into :.

The encoder therefore emitted a modified unshifted codepoint instead of the translated printable text.

Fix

• Derive the unshifted codepoint once from the active browser keyboard layout, retaining the existing US-layout fallback.
• Mark Shift as consumed only when Shift is pressed, the event produced one Unicode codepoint, a valid unshifted codepoint exists, and the produced character differs from that base codepoint.
• Pass that consumed-modifier mask and the same unshifted codepoint into the Ghostty WASM encoder.

This is deliberately a general shifted-printable fix rather than a colon special case. Shift remains effective for functional keys and for printable keys it does not transform, such as Shift+Space.

Behavior before and after

Input	Before	After
Shift+; in a normal shell	:	:
Shift+; after Neovim enables Kitty disambiguation	ESC[59;2u and Neovim sees ;	literal : and the command line opens
Shift+Space / Shift+Tab	Shift remains distinguishable	unchanged
Shifted printable keys on a non-US layout	could be encoded as a modified base key	browser-translated character is preserved

Scope and risk

• Limited to browser-to-PTY key encoding in apps/web/src/terminal/ghostty.
• Covers local web, hosted web, and desktop because they share this terminal implementation.
• Does not change server or WebSocket contracts, terminal session state, mobile native input, or visual rendering.
• Falls back to the prior behavior when the browser cannot provide a trustworthy unshifted codepoint.

Screenshots are not applicable because this has no visual UI change; the user-visible difference is the terminal byte sequence shown above.

Verification

• cd apps/web && vp test run src/terminal/ghostty/keyCodes.test.ts src/terminal/ghostty/runtimeAbi.test.ts --project unit — 14 tests passed.
• The helper tests cover shifted punctuation, shifted letters, a non-US layout map, Shift+Space, Shift+Tab, and unmodified text.
• The pinned Ghostty WASM ABI test enables Kitty disambiguation with CSI > 1 u and verifies Shift+; emits exactly :.
• Targeted vp lint passed for all four changed files.
• vp run --filter @t3tools/web typecheck passed.

Implemented with GPT-5.6-sol via the Codex harness in T3 Code.

---

Note

Medium Risk
Changes only browser-to-PTY key encoding for the Ghostty web terminal; behavior shifts for Shift+printable keys under Kitty modes, with tests but limited surface area outside terminal input.

Overview
Fixes shifted printable input in the web Ghostty bridge when apps use Kitty keyboard disambiguation (e.g. Neovim in the built-in terminal). The bridge always sent zero consumed modifiers, so Shift+; was encoded like a modified ; instead of plain :.

Adds ghosttyConsumedMods, which marks Shift consumed when the pressed character differs from the layout-aware unshifted codepoint (reuses the same unshifted value already passed to the encoder). encodeKey in core.ts passes that value to ghostty_key_event_set_consumed_mods instead of 0. Shift stays visible for keys where it does not change the character (space, Tab, etc.).

Unit tests cover the helper; the vendored WASM ABI test asserts Shift+; encodes as : in Kitty mode.

^{Reviewed by Cursor Bugbot for commit a4ecfbc. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Fix shifted terminal input by marking Shift as a consumed modifier when it transforms a printable character

• Adds ghosttyConsumedMods in keyCodes.ts to compute consumed modifier bits: returns the Shift bit when Shift produces a different printable character than the unshifted codepoint, otherwise returns 0.
• Updates the key event handler in core.ts to pass the result of ghosttyConsumedMods to ghostty_key_event_set_consumed_mods instead of the previous hardcoded 0.
• Behavioral Change: keys like : (Shift+Semicolon) now correctly report Shift as consumed, fixing shifted character input that was previously broken.

^{Macroscope summarized a4ecfbc.}

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[macroscopeapp]

Approvability

Verdict: Needs human review

This PR changes runtime behavior for how shifted keyboard input is processed in the terminal, affecting modifier consumption logic. While the fix has good test coverage, terminal input handling changes can have subtle effects across keyboard layouts and warrant human review.

^{You can customize Macroscope's approvability policy. Learn more.}