services/voiceKeyterms.ts

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// Voice keyterms for improving STT accuracy in the voice_stream endpoint.
//
// Provides domain-specific vocabulary hints (Deepgram "keywords") so the STT
// engine correctly recognises coding terminology, project names, and branch
// names that would otherwise be misheard.

import { basename } from 'path'
import { getProjectRoot } from '../bootstrap/state.js'
import { getBranch } from '../utils/git.js'

// ─── Global keyterms ────────────────────────────────────────────────

const GLOBAL_KEYTERMS: readonly string[] = [
  // Terms Deepgram consistently mangles without keyword hints.
  // Note: "Claude" and "Anthropic" are already server-side base keyterms.
  // Avoid terms nobody speaks aloud as-spelled (stdout → "standard out").
  'MCP',
  'symlink',
  'grep',
  'regex',
  'localhost',
  'codebase',
  'TypeScript',
  'JSON',
  'OAuth',
  'webhook',
  'gRPC',
  'dotfiles',
  'subagent',
  'worktree',
]

// ─── Helpers ────────────────────────────────────────────────────────

/**
 * Split an identifier (camelCase, PascalCase, kebab-case, snake_case, or
 * path segments) into individual words.  Fragments of 2 chars or fewer are
 * discarded to avoid noise.
 */
export function splitIdentifier(name: string): string[] {
  return name
    .replace(/([a-z])([A-Z])/g, '$1 $2')
    .split(/[-_./\s]+/)
    .map(w => w.trim())
    .filter(w => w.length > 2 && w.length <= 20)
}

function fileNameWords(filePath: string): string[] {
  const stem = basename(filePath).replace(/\.[^.]+$/, '')
  return splitIdentifier(stem)
}

// ─── Public API ─────────────────────────────────────────────────────

const MAX_KEYTERMS = 50

/**
 * Build a list of keyterms for the voice_stream STT endpoint.
 *
 * Combines hardcoded global coding terms with session context (project name,
 * git branch, recent files) without any model calls.
 */
export async function getVoiceKeyterms(
  recentFiles?: ReadonlySet<string>,
): Promise<string[]> {
  const terms = new Set<string>(GLOBAL_KEYTERMS)

  // Project root basename as a single term — users say "claude CLI internal"
  // as a phrase, not isolated words. Keeping the whole basename lets the
  // STT's keyterm boosting match the phrase regardless of separator.
  try {
    const projectRoot = getProjectRoot()
    if (projectRoot) {
      const name = basename(projectRoot)
      if (name.length > 2 && name.length <= 50) {
        terms.add(name)
      }
    }
  } catch {
    // getProjectRoot() may throw if not initialised yet — ignore
  }

  // Git branch words (e.g. "feat/voice-keyterms" → "feat", "voice", "keyterms")
  try {
    const branch = await getBranch()
    if (branch) {
      for (const word of splitIdentifier(branch)) {
        terms.add(word)
      }
    }
  } catch {
    // getBranch() may fail if not in a git repo — ignore
  }

  // Recent file names — only scan enough to fill remaining slots
  if (recentFiles) {
    for (const filePath of recentFiles) {
      if (terms.size >= MAX_KEYTERMS) break
      for (const word of fileNameWords(filePath)) {
        terms.add(word)
      }
    }
  }

  return [...terms].slice(0, MAX_KEYTERMS)
}