patch-btw.md

Patch Claude Code's "btw" Side Questions Feature

Enable the hidden "btw" side questions feature that's implemented but disabled.

Step 1: Find and backup cli.js

CLI_JS=$(which claude | xargs readlink -f | xargs dirname)/cli.js
echo "cli.js: $CLI_JS"
ls -la "$CLI_JS"

BACKUP="/tmp/claude-cli-backup-$(date +%Y%m%d-%H%M%S).js"
cp "$CLI_JS" "$BACKUP"
echo "Backup: $BACKUP"

Step 2: Find the stubbed functions

Pattern 1: Detection function

Returns {isBtw:!1,question:""} (always false). Find its name:

grep -oP 'function \K[a-zA-Z0-9]+(?=\(A\)\{return\{isBtw:!1,question:""\}\})' "$CLI_JS"

Expected: A function name like sW1 or AV1.

Pattern 2: Highlighting function

Returns [] (no highlights) and appears right before the detection function:

DETECT=$(grep -oP 'function \K[a-zA-Z0-9]+(?=\(A\)\{return\{isBtw:!1,question:""\}\})' "$CLI_JS")
grep -oP 'function \K[a-zA-Z0-9]+(?=\(A\)\{return\[\]\}function '"$DETECT"')' "$CLI_JS"

Expected: A function name like nl2 or Ba2.

Pattern 3: Verify the btw regex exists

The regex for matching "btw" should exist but be unused:

grep -oP '/\^btw\\b/[gi]+' "$CLI_JS"

Expected: /^btw\b/gi or similar.

Step 3: Apply patches

Replace DETECT_FUNC and HIGHLIGHT_FUNC with names from Step 2:

cli_js = "CLI_JS_PATH"  # Replace with path from Step 1

DETECT_FUNC = "DETECT_FUNC"      # From Step 2 Pattern 1
HIGHLIGHT_FUNC = "HIGHLIGHT_FUNC" # From Step 2 Pattern 2

with open(cli_js, 'r') as f:
    content = f.read()

# Patch 1: Detection - actually detect "btw" prefix
old1 = f'function {DETECT_FUNC}(A){{return{{isBtw:!1,question:""}}}}'
new1 = f'function {DETECT_FUNC}(A){{var m=A.match(/^btw\\b/i);return m?{{isBtw:!0,question:A.slice(m[0].length).trim()}}:{{isBtw:!1,question:""}}}}'
if old1 in content:
    content = content.replace(old1, new1)
    print(f"✓ Patch 1: Detection ({DETECT_FUNC}) - applied")
elif 'isBtw:!0' in content:
    print(f"○ Patch 1: Detection - already applied")
else:
    print(f"✗ Patch 1: Detection - pattern not found")

# Patch 2: Highlighting - highlight "btw" prefix
old2 = f'function {HIGHLIGHT_FUNC}(A){{return[]}}'
new2 = f'function {HIGHLIGHT_FUNC}(A){{var m=A.match(/^btw\\b/i);return m?[{{start:0,end:m[0].length}}]:[]}}'
if old2 in content:
    content = content.replace(old2, new2)
    print(f"✓ Patch 2: Highlighting ({HIGHLIGHT_FUNC}) - applied")
elif f'function {HIGHLIGHT_FUNC}(A){{var m=A.match' in content:
    print(f"○ Patch 2: Highlighting - already applied")
else:
    print(f"✗ Patch 2: Highlighting - pattern not found")

with open(cli_js, 'w') as f:
    f.write(content)
print("Done!")

Step 4: Verify

grep -oP 'isBtw:!0' "$CLI_JS" && echo "Detection patch OK"
grep -oP 'start:0,end:m\[0\]\.length' "$CLI_JS" && echo "Highlighting patch OK"

Usage

Restart Claude Code, then type: btw what is a monad?

The "btw" prefix highlights in warning color and the question is processed as a side question (no tools, quick response).

Debugging: When patterns aren't found

If Step 2 patterns aren't found, the code structure changed. Investigate:

Find the btw regex

grep -oP '.{30}btw.{30}' "$CLI_JS" | grep -i regex\|match\|test

Find side question handling

grep -oP '.{20}side_question.{50}' "$CLI_JS" | head -3

Find stub functions returning empty

Look for functions that return !1 (false) or [] near btw-related code:

grep -oP 'function [a-zA-Z0-9]+\(A\)\{return(\[\]|\{[^}]*:!1)' "$CLI_JS" | head -10

Find the tip definition

The btw tip still shows, find where it's defined:

grep -oP '.{20}btw-side-question.{50}' "$CLI_JS"

Understand the feature

The "btw" feature lets users ask quick side questions:

1. User types btw what is X?
2. Detection function checks if input starts with "btw"
3. If detected, highlighting function marks "btw" for warning color
4. Side question handler processes the question without tools
5. Response appears inline without interrupting main conversation

The feature is fully implemented but disabled via stub functions that always return false/empty.

Find the handler

grep -oP '.{50}isBtw.{100}' "$CLI_JS" | head -3

This shows where isBtw is checked - trace back to find detection function.

Revert

cp "$BACKUP" "$CLI_JS"