fix(fleet): consume model_hint + fix socket-default trap (stand-up fixes) (#627)

Co-authored-by: Jason Woltje <jason@diversecanvas.com>
Co-committed-by: Jason Woltje <jason@diversecanvas.com>

packages/mosaic/src/commands/fleet.spec.ts

@@ -15,6 +15,7 @@ import {
   buildFleetServiceCommand,
   buildSystemdEnableCommand,
   buildSystemdDisableCommand,
+  socketArgs,
   buildSystemdShowCommand,
   buildTmuxListPanesCommand,
   buildTmuxListSessionsCommand,
@@ -114,7 +115,7 @@ describe('fleet roster parsing', () => {
     }
   });
 
-  it('defaults local canary rosters to the isolated mosaic-factory socket', async () => {
+  it('defaults a socket-less roster to the literal default tmux socket (empty, no -L)', async () => {
     cleanup = await tempDir();
     const rosterPath = join(cleanup, 'roster.yaml');
     await writeFile(
@@ -131,12 +132,55 @@ describe('fleet roster parsing', () => {
 
     const roster = await loadFleetRoster(rosterPath);
 
-    expect(roster.tmux.socketName).toBe('mosaic-factory');
+    expect(roster.tmux.socketName).toBe(''); // absent ⇒ default socket (no -L), not mosaic-factory
     expect(roster.tmux.holderSession).toBe('_holder');
     expect(roster.agents).toHaveLength(1);
     expect(getRosterAgent(roster, 'canary-pi').runtime).toBe('pi');
   });
 
+  it('socketArgs: named socket → -L <name>; empty → no -L (default socket)', () => {
+    expect(socketArgs('mosaic-factory')).toEqual(['-L', 'mosaic-factory']);
+    expect(socketArgs('')).toEqual([]);
+  });
+
+  it('honors an explicit socket_name (renders -L) — containment for shipped presets', async () => {
+    cleanup = await tempDir();
+    const rosterPath = join(cleanup, 'roster.yaml');
+    await writeFile(
+      rosterPath,
+      [
+        'version: 1',
+        'transport: tmux',
+        'tmux:',
+        '  socket_name: mosaic-factory',
+        'agents:',
+        '  - name: canary-pi',
+        '    runtime: pi',
+      ].join('\n'),
+    );
+    const roster = await loadFleetRoster(rosterPath);
+    expect(roster.tmux.socketName).toBe('mosaic-factory');
+    expect(buildTmuxListSessionsCommand(roster.tmux.socketName)).toContain('-L');
+  });
+
+  it('maps a per-agent model_hint into MOSAIC_AGENT_MODEL', async () => {
+    cleanup = await tempDir();
+    const rosterPath = join(cleanup, 'roster.json');
+    await writeFile(
+      rosterPath,
+      JSON.stringify({
+        version: 1,
+        transport: 'tmux',
+        agents: [{ name: 'coder0', runtime: 'pi', model_hint: 'openai-codex/gpt-5.5:high' }],
+      }),
+    );
+    const roster = await loadFleetRoster(rosterPath);
+    const env = generateAgentEnv(roster, getRosterAgent(roster, 'coder0'));
+    expect(env).toContain('MOSAIC_AGENT_MODEL=openai-codex/gpt-5.5:high');
+    // socket-less roster ⇒ a bare empty socket (no quotes), so spawn uses no -L
+    expect(env).toContain('MOSAIC_TMUX_SOCKET=\n');
+  });
+
   it('generates deterministic per-agent EnvironmentFile content', async () => {
     cleanup = await tempDir();
     const rosterPath = join(cleanup, 'roster.json');
@@ -156,6 +200,7 @@ describe('fleet roster parsing', () => {
       [
         'MOSAIC_AGENT_NAME=coder0',
         'MOSAIC_AGENT_RUNTIME=codex',
+        'MOSAIC_AGENT_MODEL=',
         'MOSAIC_AGENT_WORKDIR=/srv/mosaic',
         'MOSAIC_TMUX_SOCKET=mosaic-factory',
         '',
@@ -355,8 +400,9 @@ describe('fleet command construction', () => {
     try {
       await program.parseAsync(['node', 'mosaic', 'fleet', 'verify']);
       expect(calls).toEqual([
-        ['tmux', '-L', 'mosaic-factory', 'has-session', '-t', '=_holder:0.0'],
-        ['tmux', '-L', 'mosaic-factory', 'has-session', '-t', '=coder0:0.0'],
+        // socket-less roster ⇒ default tmux socket (no -L)
+        ['tmux', 'has-session', '-t', '=_holder:0.0'],
+        ['tmux', 'has-session', '-t', '=coder0:0.0'],
       ]);
     } finally {
       await rm(home, { recursive: true, force: true });
@@ -637,7 +683,7 @@ describe('fleet command construction', () => {
     try {
       await program.parseAsync(['node', 'mosaic', 'agent', 'status', 'json-agent']);
       expect(calls).toEqual([
-        ['tmux', '-L', 'mosaic-factory', 'has-session', '-t', '=json-agent:0.0'],
+        ['tmux', 'has-session', '-t', '=json-agent:0.0'], // socket-less ⇒ no -L
       ]);
     } finally {
       await rm(home, { recursive: true, force: true });
@@ -677,8 +723,6 @@ describe('fleet command construction', () => {
       expect(calls).toEqual([
         [
           join(home, 'tools', 'tmux', 'agent-send.sh'),
-          '-L',
-          'mosaic-factory',
           '-S',
           getDefaultOperatorSourceLabel(),
           '-s',
@@ -727,8 +771,6 @@ describe('fleet command construction', () => {
       expect(calls).toEqual([
         [
           join(home, 'tools', 'tmux', 'agent-send.sh'),
-          '-L',
-          'mosaic-factory',
           '-S',
           'lead:manual',
           '-s',
@@ -811,9 +853,11 @@ describe('fleet ps — command construction', () => {
     ]);
   });
 
-  it('uses DEFAULT_SOCKET_NAME when socket is omitted from list-panes', () => {
+  it('uses the default tmux socket (no -L) when socket is omitted from list-panes', () => {
     const cmd = buildTmuxListPanesCommand('canary-pi');
-    expect(cmd[2]).toBe('mosaic-factory');
+    expect(cmd).not.toContain('-L'); // omitted socket ⇒ default socket
+    expect(cmd[0]).toBe('tmux');
+    expect(cmd[1]).toBe('list-panes');
   });
 
   it('derives heartbeat path under ~/.config/mosaic/fleet/run/', () => {
@@ -1331,8 +1375,9 @@ describe('fleet ps — command sequences issued', () => {
       await program.parseAsync(['node', 'mosaic', 'fleet', 'ps']);
       expect(calls).toEqual([
         buildSystemdShowCommand('coder0'),
-        buildTmuxListPanesCommand('coder0', 'mosaic-factory'),
-        buildTmuxListSessionsCommand('mosaic-factory'),
+        // socket-less roster ⇒ default socket (no -L)
+        buildTmuxListPanesCommand('coder0'),
+        buildTmuxListSessionsCommand(),
       ]);
     } finally {
       console.log = origLog;
@@ -1353,9 +1398,10 @@ describe('buildTmuxListSessionsCommand', () => {
     ]);
   });
 
-  it('uses DEFAULT_SOCKET_NAME when socket is omitted', () => {
+  it('uses the default tmux socket (no -L) when socket is omitted', () => {
     const cmd = buildTmuxListSessionsCommand();
-    expect(cmd[2]).toBe('mosaic-factory');
+    expect(cmd).not.toContain('-L');
+    expect(cmd).toEqual(['tmux', 'list-sessions', '-F', '#{session_name}']);
   });
 });
 
@@ -1633,9 +1679,10 @@ describe('agent watch', () => {
     ]);
   });
 
-  it('buildAgentWatchCommand (deprecated) still uses DEFAULT_SOCKET_NAME when socket is omitted', () => {
+  it('buildAgentWatchCommand (deprecated) uses the default tmux socket (no -L) when socket is omitted', () => {
     const cmd = buildAgentWatchCommand('canary-pi');
-    expect(cmd[2]).toBe('mosaic-factory');
+    expect(cmd).not.toContain('-L'); // omitted socket ⇒ default socket
+    expect(cmd[0]).toBe('tmux');
     expect(cmd).toContain('-r');
   });
 
@@ -1829,9 +1876,10 @@ describe('agent send --verify', () => {
 
       // 3 calls: BEFORE-capture, send, AFTER-capture (pane changed on first poll → accepted immediately)
       expect(calls).toHaveLength(3);
-      expect(calls[0]).toEqual(buildAgentVerifyAcceptedCommand('coder0', 'mosaic-factory', 5));
+      // socket-less roster ⇒ default socket (no -L)
+      expect(calls[0]).toEqual(buildAgentVerifyAcceptedCommand('coder0', '', 5));
       expect(calls[1]![0]).toContain('agent-send.sh');
-      expect(calls[2]).toEqual(buildAgentVerifyAcceptedCommand('coder0', 'mosaic-factory', 5));
+      expect(calls[2]).toEqual(buildAgentVerifyAcceptedCommand('coder0', '', 5));
     } finally {
       await rm(home, { recursive: true, force: true });
     }