mosaic comms send: routed messaging (tmux same-host default, fleet-comms inter-site)

Per FLEET-COMMS.md doctrine (Jason 2026-08-28): same-host seats talk over
tmux agent-send.sh; fleet-comms only when the recipient is on another
site. The command owns routing + flag translation between the two
transports (agent-send -s/-C/-L/-f/-m vs comms-send -t site/agent -c/-m);
validation, delivery semantics, and exit codes belong to the tools.

- rc=2 draft contract documented in help: never retry, confirm with
  capture-pane. Exit codes pass through both paths.
- --site requires MOSAIC_AGENT_NAME (exit 2 invocation defect when
  missing); missing fleet-comms checkout exits 127 naming the path.
- Specs (routing + translation + passthrough with stub tools) green.

packages/mosaic/src/cli.ts

@@ -11,6 +11,7 @@ import { registerQualityRails } from '@mosaicstack/quality-rails';
 import { registerQueueCommand } from '@mosaicstack/queue';
 import { registerStorageCommand } from '@mosaicstack/storage';
 import { registerTelemetryCommand } from './commands/telemetry.js';
+import { registerCommsCommand } from './commands/comms.js';
 import { registerQCommand } from './commands/q.js';
 import { registerWatchCommand } from './commands/watch.js';
 import { registerAgentCommand } from './commands/agent.js';
@@ -432,6 +433,7 @@ registerSkillCommand(program);
 registerTelemetryCommand(program);
 registerWatchCommand(program);
 registerQCommand(program);
+registerCommsCommand(program);
 
 // ─── update ─────────────────────────────────────────────────────────────
 

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

@@ -0,0 +1,137 @@
+import {
+  chmodSync,
+  existsSync,
+  mkdirSync,
+  mkdtempSync,
+  writeFileSync,
+  readFileSync,
+} from 'node:fs';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+
+import { Command } from 'commander';
+import { afterEach, describe, expect, it } from 'vitest';
+
+import { fleetCommsSendArgs, registerCommsCommand, tmuxSendArgs } from './comms.js';
+
+describe('arg translation', () => {
+  it('tmux path: -s/-C/-L/-f/-m per agent-send.sh getopts', () => {
+    expect(tmuxSendArgs('orch-01', 'hello', {})).toEqual(['-s', 'orch-01', '-m', 'hello']);
+    expect(
+      tmuxSendArgs('orch-01', 'unused', {
+        class: 'actionable',
+        socket: 'mosaic-fleet',
+        file: '/tmp/body.txt',
+      }),
+    ).toEqual(['-s', 'orch-01', '-C', 'actionable', '-L', 'mosaic-fleet', '-f', '/tmp/body.txt']);
+  });
+
+  it('fleet-comms path: -t site/agent and -c class', () => {
+    expect(fleetCommsSendArgs('usc', 'fred', 'hi', {})).toEqual(['-t', 'usc/fred', '-m', 'hi']);
+    expect(fleetCommsSendArgs('usc', 'fred', 'hi', { class: 'human' })).toEqual([
+      '-t',
+      'usc/fred',
+      '-c',
+      'human',
+      '-m',
+      'hi',
+    ]);
+  });
+});
+
+describe('registerCommsCommand routing', () => {
+  const savedBrain = process.env['MOSAIC_BRAIN_HOME'];
+  const savedRepo = process.env['MOSAIC_FLEET_COMMS_REPO'];
+  const savedAgent = process.env['MOSAIC_AGENT_NAME'];
+  afterEach(() => {
+    for (const [k, v] of [
+      ['MOSAIC_BRAIN_HOME', savedBrain],
+      ['MOSAIC_FLEET_COMMS_REPO', savedRepo],
+      ['MOSAIC_AGENT_NAME', savedAgent],
+    ] as const) {
+      if (v === undefined) delete process.env[k];
+      else process.env[k] = v;
+    }
+    process.exitCode = undefined;
+  });
+
+  function fixture(): { brain: string; repo: string; tmuxLog: string; commsLog: string } {
+    const brain = mkdtempSync(join(tmpdir(), 'comms-brain-'));
+    const repo = mkdtempSync(join(tmpdir(), 'comms-repo-'));
+    mkdirSync(join(brain, 'tools', 'tmux'), { recursive: true });
+    mkdirSync(join(repo, 'tools'), { recursive: true });
+    const tmuxLog = join(brain, 'tmux.log');
+    const commsLog = join(repo, 'comms.log');
+    writeFileSync(
+      join(brain, 'tools', 'tmux', 'agent-send.sh'),
+      `#!/usr/bin/env bash\nprintf '%s\\n' "$*" >> ${JSON.stringify(tmuxLog)}\nexit 7\n`,
+    );
+    writeFileSync(
+      join(repo, 'tools', 'comms-send.sh'),
+      `#!/usr/bin/env bash\nprintf '%s\\n' "$*" >> ${JSON.stringify(commsLog)}\nexit 5\n`,
+    );
+    chmodSync(join(brain, 'tools', 'tmux', 'agent-send.sh'), 0o755);
+    chmodSync(join(repo, 'tools', 'comms-send.sh'), 0o755);
+    process.env['MOSAIC_BRAIN_HOME'] = brain;
+    process.env['MOSAIC_FLEET_COMMS_REPO'] = repo;
+    process.env['MOSAIC_AGENT_NAME'] = 'tester';
+    return { brain, repo, tmuxLog, commsLog };
+  }
+
+  it('default routes same-host via agent-send with translated flags and passes rc through', async () => {
+    const f = fixture();
+    const program = new Command();
+    registerCommsCommand(program);
+    await program.parseAsync(
+      [
+        'comms',
+        'send',
+        'orch-01',
+        '--class',
+        'actionable',
+        '--socket',
+        'mosaic-fleet',
+        'verdict',
+        'landed',
+      ],
+      { from: 'user' },
+    );
+    expect(process.exitCode).toBe(7);
+    expect(readFileSync(f.tmuxLog, 'utf8').trim()).toBe(
+      '-s orch-01 -C actionable -L mosaic-fleet -m verdict landed',
+    );
+    expect(existsSync(f.commsLog)).toBe(false); // inter-site tool never invoked
+  });
+
+  it('--site routes inter-site via comms-send with site-prefixed target and passes rc through', async () => {
+    const f = fixture();
+    const program = new Command();
+    registerCommsCommand(program);
+    await program.parseAsync(
+      ['comms', 'send', 'fred', '--site', 'usc', '--class', 'human', 'hello', 'there'],
+      { from: 'user' },
+    );
+    expect(process.exitCode).toBe(5);
+    expect(readFileSync(f.commsLog, 'utf8').trim()).toBe('-t usc/fred -c human -m hello there');
+    expect(existsSync(f.tmuxLog)).toBe(false); // same-host tool never invoked
+  });
+
+  it('inter-site without MOSAIC_AGENT_NAME is an invocation defect (exit 2)', async () => {
+    const f = fixture();
+    delete process.env['MOSAIC_AGENT_NAME'];
+    const program = new Command();
+    registerCommsCommand(program);
+    await program.parseAsync(['comms', 'send', 'fred', '--site', 'usc', 'hi'], { from: 'user' });
+    expect(process.exitCode).toBe(2);
+    expect(existsSync(f.commsLog)).toBe(false); // inter-site tool never invoked
+  });
+
+  it('missing fleet-comms repo fails 127 naming the expected path', async () => {
+    fixture();
+    process.env['MOSAIC_FLEET_COMMS_REPO'] = '/nonexistent-comms-repo';
+    const program = new Command();
+    registerCommsCommand(program);
+    await program.parseAsync(['comms', 'send', 'fred', '--site', 'usc', 'hi'], { from: 'user' });
+    expect(process.exitCode).toBe(127);
+  });
+});

packages/mosaic/src/commands/comms.ts

@@ -0,0 +1,131 @@
+import type { Command } from 'commander';
+import { spawnSync } from 'node:child_process';
+import { accessSync, constants } from 'node:fs';
+import { homedir } from 'node:os';
+import { join } from 'node:path';
+
+import { DEFAULT_MOSAIC_HOME } from '../constants.js';
+import { execBrainTool } from './brain-dispatch.js';
+
+/**
+ * `mosaic comms send` — routed agent messaging (FLEET-COMMS.md doctrine).
+ *
+ * Same-host (default): brain tools/tmux/agent-send.sh. Inter-site
+ * (--site <site>): the fleet-comms repo's comms-send.sh — never for
+ * local traffic (a git round trip per message; Jason 2026-08-28).
+ *
+ * Exit codes pass through BOTH paths. rc=2 (text in pane, still draft) is
+ * a CONTRACT, not a failure: never retry, confirm with capture-pane.
+ */
+export interface CommsSendOptions {
+  readonly class?: string;
+  readonly file?: string;
+  readonly socket?: string;
+  readonly site?: string;
+  readonly commsRepo?: string;
+}
+
+export function defaultCommsRepo(): string {
+  return process.env['MOSAIC_FLEET_COMMS_REPO'] ?? join(homedir(), 'src', 'fleet-comms');
+}
+
+/** Build the agent-send.sh argv for the same-host path. */
+export function tmuxSendArgs(target: string, message: string, opts: CommsSendOptions): string[] {
+  const args = ['-s', target];
+  if (opts.class) args.push('-C', opts.class);
+  if (opts.socket) args.push('-L', opts.socket);
+  if (opts.file) args.push('-f', opts.file);
+  else args.push('-m', message);
+  return args;
+}
+
+/** Build the comms-send.sh argv for the inter-site path. */
+export function fleetCommsSendArgs(
+  site: string,
+  target: string,
+  message: string,
+  opts: CommsSendOptions,
+): string[] {
+  const args = ['-t', `${site}/${target}`];
+  if (opts.class) args.push('-c', opts.class);
+  args.push('-m', message);
+  return args;
+}
+
+export function registerCommsCommand(program: Command): void {
+  const cmd: Command = program
+    .command('comms')
+    .description(
+      'Routed agent messaging: tmux same-host (default), fleet-comms inter-site (--site)',
+    )
+    .command('send')
+    .description('send <target> [message...] — same-host tmux unless --site is given')
+    .option('--class <class>', 'terminal-log | actionable | human | reaction | digest')
+    .option('--file <path>', 'message body from file (same-host path only)')
+    .option('--socket <name>', 'tmux socket for the same-host send (e.g. mosaic-fleet)')
+    .option('--site <site>', 'route via fleet-comms to <site>/<target>')
+    .option('--comms-repo <path>', 'fleet-comms checkout', defaultCommsRepo())
+    .argument('<target>', 'destination seat (session name)')
+    .argument('[message...]', 'message text (joined; or use --file)')
+    .action(
+      async (
+        target: string,
+        messageWords: string[],
+        opts: CommsSendOptions & Record<string, unknown>,
+        command: Command,
+      ) => {
+        let mosaicHome: string | undefined;
+        for (let anc: Command | null = command; anc; anc = anc.parent) {
+          const v = (anc.opts() as Record<string, string | undefined>)['mosaicHome'];
+          if (v !== undefined) {
+            mosaicHome = v;
+            break;
+          }
+        }
+        const home = mosaicHome ?? DEFAULT_MOSAIC_HOME;
+        const message = messageWords.join(' ');
+
+        if (opts.site) {
+          const repo = opts.commsRepo ?? defaultCommsRepo();
+          const tool = join(repo, 'tools', 'comms-send.sh');
+          try {
+            accessSync(tool, constants.X_OK);
+          } catch {
+            console.error(
+              `mosaic comms: fleet-comms sender not found (expected ${tool}). ` +
+                'Clone the fleet-comms repo or point --comms-repo at it.',
+            );
+            process.exitCode = 127;
+            return;
+          }
+          if (!process.env['MOSAIC_AGENT_NAME']) {
+            console.error(
+              'mosaic comms: inter-site sends require MOSAIC_AGENT_NAME (sending identity).',
+            );
+            process.exitCode = 2; // invocation defect: fixable by the caller
+            return;
+          }
+          const env = { ...process.env, FLEET_COMMS_SITE: opts.site };
+          const result = spawnSync(tool, fleetCommsSendArgs(opts.site, target, message, opts), {
+            stdio: 'inherit',
+            env,
+          });
+          process.exitCode = result.status ?? 125;
+          return;
+        }
+
+        // Same-host: the brain tool owns validation (bad class -> its rc 3)
+        // and absence (execBrainTool -> 127 with the resolved path).
+        process.exitCode = execBrainTool(
+          home,
+          'tools/tmux/agent-send.sh',
+          tmuxSendArgs(target, message, opts),
+        );
+      },
+    );
+
+  cmd.addHelpText(
+    'after',
+    '\nExit codes pass through. rc=2 means the text reached the pane but is still a draft: NEVER retry (double-send); confirm with tmux capture-pane.',
+  );
+}