docs(custom-model): align the docs and comments with the core behaviour

src/web/public/i18n.js

@@ -616,8 +616,8 @@
     'Optional. Left blank on edit keeps the existing key.': '可选。编辑时留空将保留现有密钥。',
     'Auth header': '认证请求头',
     'Default context length (tokens)': '默认上下文长度（token 数）',
-    'Used for models whose size cannot be discovered. Leave empty to let each CLI assume its own default.':
-      '用于无法自动发现上下文大小的模型。留空则让各个 CLI 使用其自身的默认值。',
+    "Used for models whose size cannot be discovered. The model's whole window; the Claude floor check divides it by any stored slot count. Leave empty to let each CLI assume its own default.":
+      '用于无法自动发现上下文大小的模型。这是模型的完整窗口；Claude 下限检查会将其除以已存储的槽位数。留空则让各个 CLI 使用其自身的默认值。',
     'Never send both — some servers hang indefinitely.': '切勿同时发送两者 — 部分服务器会因此无限期挂起。',
     'Authorization: Bearer (default)': 'Authorization: Bearer（默认）',
     'api-key header (Azure)': 'api-key 请求头（Azure）',

src/web/public/index.html

@@ -2800,7 +2800,7 @@
                         <input type="text" id="customModelHostBaseUrl" class="set-input" placeholder="http://192.168.1.50:8080">
                       </div>
                       <div class="set-row has-field">
-                        <div class="set-row-text"><span class="set-row-label">Default context length (tokens)</span><span class="set-row-desc">Used for models whose size cannot be discovered. Leave empty to let each CLI assume its own default.</span></div>
+                        <div class="set-row-text"><span class="set-row-label">Default context length (tokens)</span><span class="set-row-desc">Used for models whose size cannot be discovered. The model's whole window; the Claude floor check divides it by any stored slot count. Leave empty to let each CLI assume its own default.</span></div>
                         <input type="number" id="customModelHostDefaultContextLength" class="set-input" min="1" max="100000000" step="1" placeholder="131072">
                       </div>
                       <div class="set-row has-field">

src/web/routes/custom-model-routes.ts

@@ -165,7 +165,7 @@ export interface DiscoveryResult {
    * over) any listed figure for the same model.
    */
   contextLengths: Record<string, number>;
-  /** See `CustomModelHost.modelSlotCounts`; populated on the same loaded-models-only basis as `contextLengths`. */
+  /** See `CustomModelHost.modelSlotCounts`; populated only for models the server reports loaded (launch command or `/props`). No listing states a slot count, unlike `contextLengths`. */
   slotCounts: Record<string, number>;
   /** See `CustomModelHost.modelSizesGB` — populated for every model whose own listing states one. */
   sizesGB: Record<string, number>;

src/web/routes/session-routes.ts

@@ -1611,7 +1611,8 @@ export function registerSessionRoutes(
     }
 
     // A CLI whose config alone cannot select the model also gets its `model` launch param
-    // forced (pi/omp `custom/<id>`, grok's block name). The argv engine DROPS a token that
+    // forced (pi/omp `custom/<id>`, grok's block name, and codex now carries its bare
+    // selected id too). The argv engine DROPS a token that
     // fails its pattern rather than quoting it, which would silently launch the CLI on its
     // own default provider again, so refuse an id the pattern cannot carry up front.
     const modelSpec = entry.launch.params.model;