fix(cli): improve daemon lifecycle and socket security

Addresses all critical and high-priority code review issues:

**Daemon Lifecycle (Critical)**
- Add socket-based shutdown handshake (SHUTDOWN command with OK acknowledgment)
- Implement daemon health checks using parent PID monitoring (every 10s)
- Graceful cleanup with 1s timeout, fallback to force kill
- Prevents orphaned daemon processes

**Socket Security (High)**
- Use XDG_RUNTIME_DIR when available (user-specific, tmpfs-backed)
- Fallback to tmpdir() on non-XDG systems
- Set socket permissions to 0600 (owner-only access)
- Clean up stale socket files on startup

**Connection Reliability (High)**
- Implement retry logic with 5 attempts, 200ms delay
- Promise-based connection with proper event handling
- Remove verbose retry logging, keep only final status

**Code Quality**
- Extract magic numbers to named constants (timing, luminance coefficients)
- Fix type safety: clients Set<any> → Set<Socket>
- Add TTY write validation (verify bytes written)
- Extract duplicated OSC fallback logic into helper function
- Track and cleanup file watchers to prevent memory leaks
- Add structured debug logging for troubleshooting

**Testing**
- Fix integration test mock to return proper writeSync byte count
- All 20 tests passing
- Verified daemon cleanup in real-world scenarios
- Confirmed binary build skips daemon spawning

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: brandonkachen

cli/package.json

@@ -17,7 +17,7 @@
   "scripts": {
     "dev": "./scripts/dev.sh",
     "prebuild": "bun run build:sdk",
-    "build": "bun build src/index.tsx --outdir dist --target node --format esm",
+    "build": "bun build src/index.tsx src/utils/terminal-theme-daemon.ts --outdir dist --target node --format esm",
     "build:sdk": "cd ../sdk && bun run build",
     "build:sdk-types": "cd ../sdk && bun run build:types",
     "build:binary": "bun ./scripts/build-binary.ts codecane $npm_package_version",

cli/src/utils/__tests__/terminal-color-detection.integration.test.ts

@@ -39,7 +39,11 @@ describe('detectTerminalTheme (integration)', () => {
       }),
     )
     spies.push(spyOn(fs, 'closeSync').mockImplementation(() => {}))
-    spies.push(spyOn(fs, 'writeSync').mockImplementation(() => 0 as any))
+    // Mock writeSync to return the length of what was written (indicates success)
+    spies.push(spyOn(fs, 'writeSync').mockImplementation((_fd, data) => {
+      const length = typeof data === 'string' ? Buffer.byteLength(data) : (data as Buffer).length
+      return length
+    }))
     spies.push(
       spyOn(fs, 'createReadStream').mockImplementation(() => {
         createReadStreamInstance = new FakeReadStream()

cli/src/utils/markdown-renderer.tsx

@@ -28,7 +28,10 @@ import type {
 import type { ReactNode } from 'react'
 
 // Helper component to work around TypeScript's Fragment key typing issue
-const KeyedFragment = React.Fragment as React.FC<{ key?: string | number; children?: ReactNode }>
+const KeyedFragment = React.Fragment as React.FC<{
+  key?: string | number
+  children?: ReactNode
+}>
 
 // Helper to wrap segments in KeyedFragments
 const wrapSegmentsInFragments = (
@@ -60,17 +63,17 @@ export interface MarkdownRenderOptions {
 
 const defaultPalette: MarkdownPalette = {
   inlineCodeFg: 'brightYellow',
-  codeBackground: '#1f2933',
-  codeHeaderFg: '#6b7280',
+  codeBackground: '#0d1117',
+  codeHeaderFg: '#666',
   headingFg: {
-    1: 'yellow',
-    2: 'yellow',
-    3: 'yellow',
-    4: 'yellow',
-    5: 'yellow',
-    6: 'yellow',
+    1: 'magenta',
+    2: 'green',
+    3: 'green',
+    4: 'green',
+    5: 'green',
+    6: 'green',
   },
-  listBulletFg: 'gray',
+  listBulletFg: 'white',
   blockquoteBorderFg: 'gray',
   blockquoteTextFg: 'gray',
   dividerFg: '#666',
@@ -103,10 +106,7 @@ const resolvePalette = (
   return palette
 }
 
-const processor = unified()
-  .use(remarkParse)
-  .use(remarkGfm)
-  .use(remarkBreaks)
+const processor = unified().use(remarkParse).use(remarkGfm).use(remarkBreaks)
 
 type MarkdownNode = Content | Root
 
@@ -201,7 +201,11 @@ const hasUnescapedMarker = (value: string): boolean => {
     let idx = value.indexOf(marker)
     while (idx !== -1) {
       let backslashes = 0
-      for (let offset = idx - 1; offset >= 0 && value[offset] === '\\'; offset -= 1) {
+      for (
+        let offset = idx - 1;
+        offset >= 0 && value[offset] === '\\';
+        offset -= 1
+      ) {
         backslashes += 1
       }
       if (backslashes % 2 === 0) {
@@ -225,7 +229,11 @@ const findClosingDelimiter = (
       return -1
     }
     let backslashes = 0
-    for (let offset = idx - 1; offset >= 0 && value[offset] === '\\'; offset -= 1) {
+    for (
+      let offset = idx - 1;
+      offset >= 0 && value[offset] === '\\';
+      offset -= 1
+    ) {
       backslashes += 1
     }
     if (backslashes % 2 === 0) {
@@ -295,10 +303,9 @@ const parseInlineFallback = (value: string): InlineFallbackNode[] => {
         (node) => !(node.type === 'text' && node.value.length === 0),
       )
 
-      const emphasisNode: InlineFallbackNode =
-        isDouble
-          ? { type: 'strong', children }
-          : { type: 'emphasis', children }
+      const emphasisNode: InlineFallbackNode = isDouble
+        ? { type: 'strong', children }
+        : { type: 'emphasis', children }
 
       nodes.push(emphasisNode)
       index = closing + markerLength
@@ -371,7 +378,9 @@ const nodeToPlainText = (node: MarkdownNode): string => {
       return getChildrenText((node as Root).children as MarkdownNode[])
 
     case 'paragraph':
-      return getChildrenText((node as Paragraph).children as MarkdownNode[]) + '\n\n'
+      return (
+        getChildrenText((node as Paragraph).children as MarkdownNode[]) + '\n\n'
+      )
 
     case 'text':
       return (node as Text).value
@@ -398,7 +407,9 @@ const nodeToPlainText = (node: MarkdownNode): string => {
         list.children
           .map((item, idx) => {
             const marker = list.ordered ? `${(list.start ?? 1) + idx}. ` : '- '
-            const text = getChildrenText((item as ListItem).children as MarkdownNode[]).trimEnd()
+            const text = getChildrenText(
+              (item as ListItem).children as MarkdownNode[],
+            ).trimEnd()
             return marker + text
           })
           .join('\n') + '\n\n'
@@ -430,20 +441,23 @@ const nodeToPlainText = (node: MarkdownNode): string => {
 
     case 'link': {
       const link = node as Link
-      const label = link.children.length > 0
-        ? getChildrenText(link.children as MarkdownNode[])
-        : link.url
+      const label =
+        link.children.length > 0
+          ? getChildrenText(link.children as MarkdownNode[])
+          : link.url
       return label
     }
 
     case 'table': {
       const table = node as Table
-      return table.children
-        .map((row) => {
-          const cells = (row as TableRow).children as TableCell[]
-          return cells.map((cell) => nodeToPlainText(cell)).join(' | ')
-        })
-        .join('\n') + '\n\n'
+      return (
+        table.children
+          .map((row) => {
+            const cells = (row as TableRow).children as TableCell[]
+            return cells.map((cell) => nodeToPlainText(cell)).join(' | ')
+          })
+          .join('\n') + '\n\n'
+      )
     }
 
     case 'tableRow':
@@ -659,7 +673,7 @@ const renderTable = (table: Table, state: RenderState): ReactNode[] => {
   // Calculate column widths
   const columnWidths: number[] = []
   table.children.forEach((row) => {
-    (row as TableRow).children.forEach((cell, colIdx) => {
+    ;(row as TableRow).children.forEach((cell, colIdx) => {
       const cellText = nodeToPlainText(cell as TableCell)
       const width = cellText.length
       columnWidths[colIdx] = Math.max(columnWidths[colIdx] || 0, width)
@@ -904,9 +918,7 @@ const mergeStreamingSegments = (segments: ReactNode[]): ReactNode => {
   return (
     <>
       {segments.map((segment, idx) => (
-        <KeyedFragment key={`stream-segment-${idx}`}>
-          {segment}
-        </KeyedFragment>
+        <KeyedFragment key={`stream-segment-${idx}`}>{segment}</KeyedFragment>
       ))}
     </>
   )

cli/src/utils/terminal-color-detection.ts

@@ -12,9 +12,15 @@ import { openSync, closeSync, writeSync, createReadStream } from 'fs'
 
 import type { ThemeName } from '../types/theme-system'
 
+// Timing constants
 const OSC_TIMEOUT_MS = 1000
 const BRIGHTNESS_THRESHOLD = 128
 
+// Luminance coefficients (ITU-R BT.709)
+const LUMINANCE_RED = 0.2126
+const LUMINANCE_GREEN = 0.7152
+const LUMINANCE_BLUE = 0.0722
+
 export function buildOscQuery(oscCode: number): string {
   const base = `\x1b]${oscCode};?\x07` // ESC ] <code> ; ? BEL
 
@@ -133,7 +139,19 @@ function queryTerminalOSC(oscCode: number): Promise<string | null> {
 
       // Send OSC query: ESC ] <code> ; ? BEL (wrapped if needed)
       const query = buildOscQuery(oscCode)
-      writeSync(ttyWriteFd!, query)
+      const bytesWritten = writeSync(ttyWriteFd!, query)
+
+      // Verify write succeeded
+      if (bytesWritten < query.length) {
+        readStream.removeListener('data', onData)
+        readStream.removeListener('error', onError)
+        try {
+          ;(readStream as any).close?.()
+        } catch {}
+        cleanup()
+        resolve(null)
+        return
+      }
     } catch {
       cleanup()
       resolve(null)
@@ -185,7 +203,7 @@ export function parseOSCResponse(
  * @returns Brightness value 0-255
  */
 function calculateBrightness([r, g, b]: [number, number, number]): number {
-  return Math.floor((2126 * r + 7152 * g + 722 * b) / 10000)
+  return Math.floor(LUMINANCE_RED * r + LUMINANCE_GREEN * g + LUMINANCE_BLUE * b)
 }
 
 function themeFromRgb(rgb: [number, number, number]): ThemeName {
@@ -199,6 +217,18 @@ function themeFromForegroundRgb(rgb: [number, number, number]): ThemeName {
   return brightness > BRIGHTNESS_THRESHOLD ? 'dark' : 'light'
 }
 
+/**
+ * Query foreground color as fallback when background query fails
+ * @returns Theme based on foreground color, or null if detection failed
+ */
+async function queryForegroundFallback(): Promise<ThemeName | null> {
+  const fgResponse = await queryTerminalOSC(10)
+  if (!fgResponse) return null
+  const fgRgb = parseOSCResponse(fgResponse)
+  if (!fgRgb) return null
+  return themeFromForegroundRgb(fgRgb)
+}
+
 /**
  * Detect terminal theme by querying background color
  * @returns 'dark' or 'light' based on background brightness, or null if detection failed
@@ -208,22 +238,12 @@ export async function detectTerminalTheme(): Promise<ThemeName | null> {
     // Query background color (OSC 11)
     const bgResponse = await queryTerminalOSC(11)
     if (!bgResponse) {
-      // Fallback: try foreground (OSC 10)
-      const fgResponse = await queryTerminalOSC(10)
-      if (!fgResponse) return null
-      const fgRgb = parseOSCResponse(fgResponse)
-      if (!fgRgb) return null
-      return themeFromForegroundRgb(fgRgb)
+      return await queryForegroundFallback()
     }
 
     const bgRgb = parseOSCResponse(bgResponse)
     if (!bgRgb) {
-      // Fallback: try foreground (OSC 10)
-      const fgResponse = await queryTerminalOSC(10)
-      if (!fgResponse) return null
-      const fgRgb = parseOSCResponse(fgResponse)
-      if (!fgRgb) return null
-      return themeFromForegroundRgb(fgRgb)
+      return await queryForegroundFallback()
     }
 
     // Calculate brightness and determine theme