107 lines
3.0 KiB
TypeScript
107 lines
3.0 KiB
TypeScript
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import { resolve, join } from 'path'
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import { homedir } from 'os'
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import { readFileSync, existsSync, statSync } from 'fs'
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const HERMES_BASE = resolve(homedir(), '.hermes')
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const MODELS_DEV_CACHE = resolve(HERMES_BASE, 'models_dev_cache.json')
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const DEFAULT_CONTEXT_LENGTH = 200_000
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interface ModelLimit {
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context?: number
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output?: number
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input?: number
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}
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interface ModelEntry {
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id?: string
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limit?: ModelLimit
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}
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interface ProviderEntry {
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models?: Record<string, ModelEntry>
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}
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// --- In-memory cache: parsed models_dev_cache (1.7MB), invalidated by mtime ---
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let _cache: Record<string, ProviderEntry> | null = null
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let _cacheMtime = 0
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const CACHE_TTL_MS = 5 * 60 * 1000 // 5 minutes
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let _cacheLoadedAt = 0
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function loadModelsDevCache(): Record<string, ProviderEntry> | null {
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if (!existsSync(MODELS_DEV_CACHE)) return null
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try {
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const stat = statSync(MODELS_DEV_CACHE)
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const now = Date.now()
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// Return cached if file hasn't changed and within TTL
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if (_cache && stat.mtimeMs === _cacheMtime && now - _cacheLoadedAt < CACHE_TTL_MS) {
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return _cache
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}
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const raw = readFileSync(MODELS_DEV_CACHE, 'utf-8')
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_cache = JSON.parse(raw) as Record<string, ProviderEntry>
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_cacheMtime = stat.mtimeMs
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_cacheLoadedAt = now
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return _cache
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} catch {
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return _cache // return stale cache on error
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}
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}
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// --- Profile helpers ---
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function getProfileDir(profile?: string): string {
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if (!profile || profile === 'default') return HERMES_BASE
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const dir = join(HERMES_BASE, 'profiles', profile)
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return existsSync(dir) ? dir : HERMES_BASE
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}
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function getDefaultModel(profileDir: string): string | null {
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const configPath = join(profileDir, 'config.yaml')
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if (!existsSync(configPath)) return null
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try {
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const content = readFileSync(configPath, 'utf-8')
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const match = content.match(/^model:\s*\n\s+default:\s*(.+)$/m)
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return match ? match[1].trim() : null
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} catch {
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return null
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}
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}
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// --- Context lookup ---
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function lookupContextFromCache(modelName: string): number | null {
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const data = loadModelsDevCache()
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if (!data) return null
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// Exact match first
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for (const prov of Object.values(data)) {
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const models = prov.models || {}
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const entry = models[modelName]
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if (entry?.limit?.context) return entry.limit.context
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}
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// Case-insensitive fallback
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const lower = modelName.toLowerCase()
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for (const prov of Object.values(data)) {
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const models = prov.models || {}
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for (const [name, entry] of Object.entries(models)) {
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if (name.toLowerCase() === lower && entry?.limit?.context) {
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return entry.limit.context
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}
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}
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}
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return null
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}
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/**
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* Get the context length for the current profile's default model.
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* Results are cached in memory (5min TTL) and invalidated by file mtime.
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*/
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export function getModelContextLength(profile?: string): number {
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const profileDir = getProfileDir(profile)
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const model = getDefaultModel(profileDir)
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if (!model) return DEFAULT_CONTEXT_LENGTH
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return lookupContextFromCache(model) || DEFAULT_CONTEXT_LENGTH
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}
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