refactor: rewrite model-context to use js-yaml, add context_length to provider form (#177)

* fix: context-length API returns 200K instead of actual model context

Two bugs cause the /api/hermes/sessions/context-length endpoint to
always return DEFAULT_CONTEXT_LENGTH (200K):

1. getModelContextLength ignores config.yaml model.context_length
   The function only checks models_dev_cache.json (which doesn't
   exist in default installations) and falls back to the hardcoded
   200K default, completely ignoring the user's explicit
   model.context_length setting in config.yaml.

2. getDefaultModel regex fails when api_key/base_url come before default
   The regex /^model:\s*\n\s+default:\s*(.+)$/m assumes 'default' is
   the first child key under 'model:', but when api_key or base_url
   appear first in the YAML, the match fails. This causes
   getModelContextLength to short-circuit to DEFAULT_CONTEXT_LENGTH
   before even reaching the cache lookup.

Fix:
- Add getDefaultModelRobust() that extracts the entire model: block
  first, then searches for default: within it
- Add getConfigContextLength() that reads model.context_length from
  config.yaml as a fallback (matching hermes-agent priority)
- Update getModelContextLength() resolution order:
  1. models_dev_cache.json (existing)
  2. config.yaml model.context_length (new)
  3. DEFAULT_CONTEXT_LENGTH (existing fallback)

Closes #169

* refactor: rewrite model-context to use js-yaml, add context_length to provider form

- Replace fragile regex-based YAML parsing with js-yaml for reliable config.yaml reads
- Fix context_length resolution priority: config.yaml override > custom_providers > models_dev_cache > 200K default
- Add context_length input field when adding custom providers in ProviderFormModal
- Backend: persist context_length to custom_providers models.<model>.context_length in config.yaml
- Add i18n keys (contextLength, contextLengthPlaceholder) to all 8 locales

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix: use NInputNumber instead of NInput type=number for context_length

NInput does not support type="number" in Naive UI.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: devilardis <53129661@qq.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

packages/server/src/controllers/hermes/providers.ts

@@ -5,9 +5,17 @@ import * as hermesCli from '../../services/hermes/hermes-cli'
 import { readConfigYaml, writeConfigYaml, saveEnvValue, PROVIDER_ENV_MAP } from '../../services/config-helpers'
 import { logger } from '../../services/logger'
 
+function buildProviderEntry(name: string, base_url: string, api_key: string, model: string, context_length?: number) {
+  const entry: any = { name, base_url, api_key, model }
+  if (context_length && context_length > 0) {
+    entry.models = { [model]: { context_length } }
+  }
+  return entry
+}
+
 export async function create(ctx: any) {
-  const { name, base_url, api_key, model, providerKey } = ctx.request.body as {
-    name: string; base_url: string; api_key: string; model: string; providerKey?: string | null
+  const { name, base_url, api_key, model, context_length, providerKey } = ctx.request.body as {
+    name: string; base_url: string; api_key: string; model: string; context_length?: number; providerKey?: string | null
   }
   console.log(name, base_url, api_key, model, providerKey)
   if (!name || !base_url || !model) {
@@ -30,8 +38,13 @@ export async function create(ctx: any) {
         existing.base_url = base_url
         existing.api_key = api_key
         existing.model = model
+        if (context_length && context_length > 0) {
+          if (!existing.models) existing.models = {}
+          existing.models[model] = existing.models[model] || {}
+          existing.models[model].context_length = context_length
+        }
       } else {
-        config.custom_providers.push({ name: name.trim().toLowerCase().replace(/ /g, '-'), base_url, api_key, model })
+        config.custom_providers.push(buildProviderEntry(name.trim().toLowerCase().replace(/ /g, '-'), base_url, api_key, model, context_length))
       }
       config.model.default = model
       config.model.provider = poolKey
@@ -51,8 +64,13 @@ export async function create(ctx: any) {
           existing.base_url = base_url
           existing.api_key = api_key
           existing.model = model
+          if (context_length && context_length > 0) {
+            if (!existing.models) existing.models = {}
+            existing.models[model] = existing.models[model] || {}
+            existing.models[model].context_length = context_length
+          }
         } else {
-          config.custom_providers.push({ name: poolKey, base_url, api_key, model })
+          config.custom_providers.push(buildProviderEntry(poolKey, base_url, api_key, model, context_length))
         }
         config.model.default = model
         config.model.provider = `custom:${poolKey}`