diff --git a/src/frontends/tui/commands.test.ts b/src/frontends/tui/commands.test.ts
index 9478979..eca95e8 100644
--- a/src/frontends/tui/commands.test.ts
+++ b/src/frontends/tui/commands.test.ts
@@ -188,6 +188,25 @@ describe('/pair command', () => {
   });
 });
 
+describe('/login command with mode subcommand', () => {
+  it('parses /login with mode subcommand', () => {
+    expect(parseCommand('/login anthropic mode oauth')).toEqual({
+      type: 'login', provider: 'anthropic', mode: 'oauth',
+    });
+    expect(parseCommand('/login openai mode api_key')).toEqual({
+      type: 'login', provider: 'openai', mode: 'api_key',
+    });
+    expect(parseCommand('/login anthropic mode auto')).toEqual({
+      type: 'login', provider: 'anthropic', mode: 'auto',
+    });
+  });
+
+  it('parses /login without mode unchanged', () => {
+    expect(parseCommand('/login')).toEqual({ type: 'login' });
+    expect(parseCommand('/login anthropic')).toEqual({ type: 'login', provider: 'anthropic' });
+  });
+});
+
 describe('PROVIDER_NAMES', () => {
   it('matches all providers from the config schema', () => {
     expect(PROVIDER_NAMES).toEqual(MODEL_PROVIDERS);
diff --git a/src/frontends/tui/commands.ts b/src/frontends/tui/commands.ts
index bebe25c..b675a0f 100644
--- a/src/frontends/tui/commands.ts
+++ b/src/frontends/tui/commands.ts
@@ -15,7 +15,7 @@ export type Command =
   | { type: 'model'; name?: string; providerModel?: string }
   | { type: 'backend'; provider?: string }
   | { type: 'runtime'; input?: string }
-  | { type: 'login'; provider?: string }
+  | { type: 'login'; provider?: string; mode?: 'api_key' | 'oauth' | 'auto' }
   | { type: 'transfer'; target: string }
   | { type: 'pair'; action?: 'generate' | 'list' | 'revoke'; args?: string }
   | { type: 'queue'; action?: 'show' | 'set' | 'reset'; args?: string }
@@ -178,8 +178,16 @@ export function parseCommand(input: string): Command | null {
     return { type: 'login' };
   }
   if (trimmed.startsWith('/login ')) {
-    const provider = trimmed.slice('/login '.length).trim();
-    return { type: 'login', provider: provider || undefined };
+    const rest = trimmed.slice('/login '.length).trim();
+    // /login <provider> mode <value>
+    const modeMatch = rest.match(/^(\S+)\s+mode\s+(\S+)$/);
+    if (modeMatch) {
+      const modeValue = modeMatch[2].toLowerCase();
+      if (modeValue === 'api_key' || modeValue === 'oauth' || modeValue === 'auto') {
+        return { type: 'login', provider: modeMatch[1] || undefined, mode: modeValue };
+      }
+    }
+    return { type: 'login', provider: rest || undefined };
   }
 
   // Pair
@@ -237,7 +245,8 @@ Commands:
   /research <task>       Delegate a task to the configured research agent
   /council <task>        Run the councils pipeline for a task
   /council preflight     Check council tier routing, endpoint/auth mode, and probe latency
-  /login [provider]      Authenticate with GitHub, OpenAI, Anthropic, or Z.AI
+  /login [provider]      Authenticate (github, openai, anthropic, zai)
+  /login <p> mode <m>    Set auth mode for provider (api_key|oauth|auto)
   /pair                  List pending pairing codes and approved senders
   /pair generate [label] Generate a new DM pairing code
   /pair revoke <ch> <id> Revoke an approved sender
@@ -318,7 +327,7 @@ export const COMMAND_TOOLTIPS: Record<string, string> = {
   '/status': 'Show session info and token usage',
   '/fullscreen': 'Switch to fullscreen mode',
   '/fs': 'Switch to fullscreen mode',
-  '/login': 'Authenticate with GitHub/OpenAI/Anthropic (OAuth/token or API key) or Z.AI (API key store)',
+  '/login': 'Authenticate with provider; use "mode api_key|oauth|auto" to switch auth mode',
   '/pair': 'Generate/list/revoke DM pairing codes',
   '/queue': 'Show or update per-session queue policy',
   '/approvals': 'List pending guarded actions for this session',