diff --git a/docs/api/routes/companysetting/set.md b/docs/api/routes/companysetting/set.md
index 8706456..84ad76d 100644
--- a/docs/api/routes/companysetting/set.md
+++ b/docs/api/routes/companysetting/set.md
@@ -6,7 +6,8 @@ Upsert company setting
 
 Sets (upserts) a company setting for the selected company.
 Only a fixed allow-list of keys can be set: `ui.theme`, `keys.tavily`,
-`keys.openrouter`, `keys.serper`, `labelprinter.addr`, `labelprinter.type`.
+`keys.openrouter`, `keys.serper`, `systemprompt-prefix`,
+`systemprompt-suffix`, `default-model`.
 
 
 ## Path parameters
diff --git a/src/api/routes/companysetting.js b/src/api/routes/companysetting.js
index e38057f..95ff0dc 100644
--- a/src/api/routes/companysetting.js
+++ b/src/api/routes/companysetting.js
@@ -5,8 +5,9 @@ const ALLOWED_KEYS = [
     'keys.tavily',
     'keys.openrouter',
     'keys.serper',
-    'labelprinter.addr',
-    'labelprinter.type',
+    'systemprompt-prefix',
+    'systemprompt-suffix',
+    'default-model',
 ];
 
 function requireSelectedCompany(req) {
@@ -206,7 +207,8 @@ export function register(app, basePath = '') {
      *     description: |
      *       Sets (upserts) a company setting for the selected company.
      *       Only a fixed allow-list of keys can be set: `ui.theme`, `keys.tavily`,
-     *       `keys.openrouter`, `keys.serper`, `labelprinter.addr`, `labelprinter.type`.
+     *       `keys.openrouter`, `keys.serper`, `systemprompt-prefix`,
+     *       `systemprompt-suffix`, `default-model`.
      *     security:
      *       - cookieAuth: []
      *     x-markdown: companysetting/set.md
diff --git a/src/services/conversationManager.js b/src/services/conversationManager.js
index 8de6391..efbabfe 100644
--- a/src/services/conversationManager.js
+++ b/src/services/conversationManager.js
@@ -73,9 +73,27 @@ function buildSkillIndex(vfsRoot) {
  * (docs/api/routes.md), read on each run so it stays current.
  *
  * @param {string} vfsRoot Resolved VFS root for this user's company, used to list SKILL files.
- * @returns {string}
+ * @param {number} [googleAuthId]
+ * @returns {Promise<string>}
  */
-async function buildSystemPrompt(vfsRoot) {
+async function buildSystemPrompt(vfsRoot, googleAuthId) {
+    let prefix = '';
+    let suffix = '';
+    if (googleAuthId) {
+        try {
+            const prefixSetting = await dbCompanySetting.getByKey(googleAuthId, 'systemprompt-prefix', { maskWriteonly: false });
+            prefix = prefixSetting?.value?.trim() || '';
+        } catch (err) {
+            console.error('conversation: failed to read systemprompt-prefix:', err.message);
+        }
+        try {
+            const suffixSetting = await dbCompanySetting.getByKey(googleAuthId, 'systemprompt-suffix', { maskWriteonly: false });
+            suffix = suffixSetting?.value?.trim() || '';
+        } catch (err) {
+            console.error('conversation: failed to read systemprompt-suffix:', err.message);
+        }
+    }
+
     let routesDoc = '';
     try {
         routesDoc = readFileSync(ROUTES_DOC_PATH, 'utf8').trim();
@@ -83,7 +101,7 @@ async function buildSystemPrompt(vfsRoot) {
         console.error('conversation: failed to read routes doc:', err);
     }
     const today = new Date().toISOString().split('T')[0];
-    return [
+    const basePrompt = [
         'You are an intelligent assistant specialized in exploring, querying, and managing data from the Dashback REST API.',
         `Today's date: ${today}`,
         '',
@@ -129,6 +147,12 @@ async function buildSystemPrompt(vfsRoot) {
         '- Format responses clearly using markdown tables, bullet lists, or bold key-value pairs where appropriate.',
         ...(routesDoc ? ['', 'DASHBACK API ROUTES:', routesDoc] : []),
     ].join('\n');
+
+    const sections = [];
+    if (prefix) sections.push(prefix);
+    sections.push(basePrompt);
+    if (suffix) sections.push(suffix);
+    return sections.join('\n\n');
 }
 
 /**
@@ -351,7 +375,7 @@ export class ConversationManager {
             const defaultModel = await resolveDefaultModel(googleAuthId);
             const hasCustomKey = await hasConfiguredOpenRouterKey(googleAuthId);
             const storedModel = typeof conversation.model === 'string' ? conversation.model.trim() : '';
-            const model = (!storedModel || RETIRED_MODELS.has(storedModel) || (storedModel === env.openrouterFreeModel && hasCustomKey))
+            const model = (!storedModel || RETIRED_MODELS.has(storedModel) || (storedModel === env.openrouterFreeModel && (hasCustomKey || defaultModel !== env.openrouterFreeModel)))
                 ? defaultModel
                 : storedModel;
             const apiKey = await resolveOpenRouterKey(googleAuthId);
@@ -369,7 +393,7 @@ export class ConversationManager {
             }
 
             const messages = [
-                { role: 'system', content: await buildSystemPrompt(vfsRoot) },
+                { role: 'system', content: await buildSystemPrompt(vfsRoot, googleAuthId) },
                 ...history.map(toLlmMessage),
             ];
 
diff --git a/src/tools/llm-key.js b/src/tools/llm-key.js
index 0fef8ba..850dacd 100644
--- a/src/tools/llm-key.js
+++ b/src/tools/llm-key.js
@@ -47,13 +47,27 @@ export async function hasConfiguredOpenRouterKey(googleAuthId) {
 
 /**
  * Resolve the default model for a user/company:
- * - As soon as the user/company has configured `keys.openrouter`, use `env.openrouterPaidModel`.
- * - Otherwise (using the server's free key), use `env.openrouterFreeModel`.
+ * - If companysetting `default-model` is set, return it (works in both paid and no-key modes).
+ * - Otherwise, if the user/company has configured `keys.openrouter`, use `env.openrouterPaidModel`
+ *   (which defaults to 'openai/gpt-6-luna:floor').
+ * - Otherwise (no key set / free mode), use `env.openrouterFreeModel`
+ *   (which defaults to 'openrouter/free').
  *
  * @param {number} [googleAuthId]
  * @returns {Promise<string>}
  */
 export async function resolveDefaultModel(googleAuthId) {
+    if (googleAuthId) {
+        try {
+            const setting = await dbCompanySetting.getByKey(googleAuthId, 'default-model', { maskWriteonly: false });
+            const customModel = setting?.value?.trim();
+            if (customModel) return customModel;
+        } catch (err) {
+            console.error('default-model: failed to read company setting:', err.message);
+        }
+    }
     const hasKey = await hasConfiguredOpenRouterKey(googleAuthId);
-    return hasKey ? env.openrouterPaidModel : env.openrouterFreeModel;
+    return hasKey
+        ? (env.openrouterPaidModel || 'openai/gpt-6-luna:floor')
+        : (env.openrouterFreeModel || 'openrouter/free');
 }
\ No newline at end of file