Fix: Prevent stored buffer resend on backspace (#96)

[pranav-n29]

Fixes #96

When pressing Backspace, the previously stored input buffer was being re-sent before the deletion occurred. This caused:
Duplicate text to appear
Previous full message to be retyped
Noticeable delay before character deletion

Summary by CodeRabbit

Release Notes

• Bug Fixes
  • Enhanced keyboard input handling with proper key press and release sequences
  • Refined text input validation for single character processing

[coderabbitai]

📝 Walkthrough

Walkthrough

The InputHandler.ts now lowercases incoming keys, maps them to nut-keys via KEY_MAP, and sends explicit press/release sequences for mapped keys. Unmapped single characters are typed directly; others are logged. Text input is restricted to single characters only, replacing previous direct typing behavior.

Changes

Cohort / File(s)	Summary
Keyboard Input Handler src/server/InputHandler.ts	Modified key handling to use explicit press/release sequences for mapped keys via KEY_MAP, with fallback to direct character typing for unmapped single characters. Restricted text input to single characters only instead of processing any text length.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐰 A hop, a skip, a keyboard fix so fine,
Keys press and release, in perfect line,
No buffers linger when backspace strikes,
Just clean keystrokes, exactly as it likes! ✨

🚥 Pre-merge checks | ✅ 6

✅ Passed checks (6 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main change: preventing stored buffer resend on backspace, which directly addresses the core issue being fixed.
Linked Issues check	✅ Passed	The code changes modify key and text handling in InputHandler.ts to distinguish between key press/release semantics and character typing, which aligns with preventing unintended buffer resend on backspace.
Out of Scope Changes check	✅ Passed	All changes are scoped to InputHandler.ts key and text handling logic, directly addressing the buffer resend issue without unrelated modifications.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Merge Conflict Detection	✅ Passed	✅ No merge conflicts detected when merging into main

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[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@src/server/InputHandler.ts`:
- Around line 160-164: The current guard in InputHandler.ts inside the switch
case 'text' drops any multi-character msg.text when it checks length === 1;
change this to preserve paste/IME input by either removing the length check and
iterating over each character in msg.text and calling keyboard.type(char) for
each, or if you prefer to keep a guard, log a warning with the dropped msg.text
before discarding so it’s diagnosable; alternatively, fix the root client-side
issue (clear buffer on Backspace) and then remove this server-side restriction.

🧹 Nitpick comments (1)

src/server/InputHandler.ts (1)

96-113: Inconsistent indentation and leftover debug logging.

Two things:

1. The case 'key' block (and case 'text' below) uses different indentation from the rest of the switch — other cases are indented at 3 levels (12 spaces), while this block starts at 4 spaces. Please align with the surrounding code.

2. Line 98: console.log on every key press is noisy for production. Consider removing it or gating it behind a debug flag.

The core logic change (using pressKey/releaseKey for mapped keys like Backspace instead of type()) correctly addresses the buffer resend bug.

Proposed fix for indentation and debug log removal

-    case 'key':
-    if (msg.key) {
-        console.log(`Processing key: ${msg.key}`);
-        const lowerKey = msg.key.toLowerCase();
-        const nutKey = KEY_MAP[lowerKey];
-
-        if (nutKey !== undefined) {
-            await keyboard.pressKey(nutKey);
-            await keyboard.releaseKey(nutKey);
-        } 
-        else if (msg.key.length === 1) {
-            await keyboard.type(msg.key);
-        } 
-        else {
-            console.log(`Unmapped key: ${msg.key}`);
-        }
-    }
-    break;
+            case 'key':
+                if (msg.key) {
+                    const lowerKey = msg.key.toLowerCase();
+                    const nutKey = KEY_MAP[lowerKey];
+
+                    if (nutKey !== undefined) {
+                        await keyboard.pressKey(nutKey);
+                        await keyboard.releaseKey(nutKey);
+                    } else if (msg.key.length === 1) {
+                        await keyboard.type(msg.key);
+                    } else {
+                        console.warn(`Unmapped key: ${msg.key}`);
+                    }
+                }
+                break;

[coderabbitai]

⚠️ Potential issue | 🟠 Major

Restricting text to single characters silently drops multi-char input (e.g., paste, IME).

The length === 1 guard fixes the backspace buffer-resend symptom, but it also silently discards any legitimate multi-character text input such as clipboard paste or IME composition strings. This could confuse users when paste stops working.

Consider either:

• Logging when text is dropped so it's at least diagnosable, or
• Fixing the root cause on the client side (clearing the buffer on Backspace) rather than restricting server-side text length, or
• Iterating over each character in the text string individually if multi-char support is needed.

Minimal improvement: iterate over characters instead of dropping

            case 'text':
-    if (msg.text && msg.text.length === 1) {
-        await keyboard.type(msg.text);
-    }
-    break;
+                if (msg.text && msg.text.length > 0) {
+                    for (const char of msg.text) {
+                        await keyboard.type(char);
+                    }
+                }
+                break;

This preserves paste/IME support while still typing character-by-character. If the real issue is duplicate sends from the client, the client-side buffer should be cleared on Backspace instead.

🤖 Prompt for AI Agents

In `@src/server/InputHandler.ts` around lines 160 - 164, The current guard in
InputHandler.ts inside the switch case 'text' drops any multi-character msg.text
when it checks length === 1; change this to preserve paste/IME input by either
removing the length check and iterating over each character in msg.text and
calling keyboard.type(char) for each, or if you prefer to keep a guard, log a
warning with the dropped msg.text before discarding so it’s diagnosable;
alternatively, fix the root client-side issue (clear buffer on Backspace) and
then remove this server-side restriction.

[imxade]

not a complete fix, first character is still being sent with backspace instead of instant deletion