diff --git a/docs/guides/fleet-local-canary.md b/docs/guides/fleet-local-canary.md
index 78ad59f..24861ff 100644
--- a/docs/guides/fleet-local-canary.md
+++ b/docs/guides/fleet-local-canary.md
@@ -17,6 +17,9 @@ Product-owned defaults:
 - `packages/mosaic/framework/tools/tmux/agent-send.sh`
 - `packages/mosaic/framework/tools/tmux/send-message.sh`
 
+These files are published through `packages/mosaic/package.json`, whose `files`
+allowlist includes `framework` along with `dist`.
+
 Site-owned local roster:
 
 ```text
@@ -66,6 +69,14 @@ These commands read the roster and target the configured tmux socket. The
 generated systemd agent services use `start-agent-session.sh`; message delivery
 uses the tmux send tools with `-L mosaic-factory`.
 
+`mosaic agent send` is operator-origin traffic unless a caller explicitly says
+otherwise. The CLI always passes a deterministic source label to
+`agent-send.sh` with `-S`, defaulting to `<hostname>:operator`, so it does not
+query the target tmux socket and accidentally identify as an active agent pane.
+Use `--source-label <label>` or `--source <label>` only when deliberately
+impersonating a known handoff lane. The lower-level inter-agent wrapper
+`agent-send.sh -S <label>` remains the explicit source override for scripts.
+
 ## Verification
 
 Use these checks before expanding the roster:
@@ -83,6 +94,27 @@ Expected results:
 - `tmux ls` shows only the default tmux server sessions and is not changed by
   fleet start/stop operations.
 - `mosaic fleet verify` checks exact session targets on the isolated socket.
+- `systemctl --user status ...` may show `active (exited)` for oneshot units;
+  that means the unit ran, not that an agent pane is live. Treat tmux
+  `has-session`, `list-panes`, process tree, and logs as the liveness evidence.
+
+## Release Preflight
+
+Run this checklist before cutting or dogfooding a fleet release:
+
+- Real AI dogfood: send at least one task through `mosaic agent send`, then
+  confirm the agent accepted/responded using pane, process, or log evidence.
+- Restart/stop/idempotency: run `mosaic fleet start`, `restart`, `stop`, and a
+  repeated `start` against the named socket; verify the default tmux server is
+  unchanged.
+- Liveness verification: run `mosaic fleet verify` and confirm roster sessions
+  with `tmux -L mosaic-factory ls` or exact `has-session` checks.
+- Package dry-run: run `npm pack --dry-run --json` from `packages/mosaic` and
+  confirm `framework/fleet`, `framework/systemd/user`,
+  `framework/tools/fleet`, and `framework/tools/tmux` assets are included.
+- Mosaic update test: install or upgrade from the packed artifact in a temporary
+  Mosaic home and confirm `mosaic update` or the release upgrade path does not
+  remove local roster/config files.
 
 ## Rollback
 
diff --git a/docs/scratchpads/2026-06-20-fleet-release-hardening.md b/docs/scratchpads/2026-06-20-fleet-release-hardening.md
new file mode 100644
index 0000000..442973d
--- /dev/null
+++ b/docs/scratchpads/2026-06-20-fleet-release-hardening.md
@@ -0,0 +1,35 @@
+# Fleet release hardening
+
+## Objective
+
+Harden the Mosaic local fleet release path for operator sends, tmux/systemd verification, package contents, and dogfood release documentation.
+
+## Constraints
+
+- Do not edit `docs/TASKS.md`.
+- Do not change production deployment refs.
+- Keep fleet transport generic and named-socket safe.
+- Preserve strict roster validation.
+- Add tests first or alongside fixes.
+
+## Plan
+
+1. Add regression tests for deterministic `mosaic agent send` source labels.
+2. Strengthen fleet status/verify/package/install-systemd coverage.
+3. Implement focused CLI/source-label changes.
+4. Update local canary documentation with dogfood preflight.
+5. Run formatting, targeted tests, typecheck, lint, and package dry-run evidence.
+
+## Evidence Log
+
+- Started from existing `docs/PRD.md`; durable local fleet canary is in v0.1.0 scope.
+- Loaded `mosaic-fleet-operations` skill; key constraints are isolated tmux sockets, no default tmux positive tests, and `active (exited)` is not liveness.
+- TDD red: `pnpm --filter @mosaicstack/mosaic test -- src/commands/fleet.spec.ts` initially failed because `node_modules` was absent; after `pnpm install`, the new source-label tests failed on missing `-S`, missing helper, and unknown `--source-label`.
+- Green implementation: `mosaic agent send` now passes `-S <hostname>:operator` by default and accepts `--source-label` / `--source` overrides.
+- Test coverage added for tmux-based fleet verify liveness, package `files` allowlist containing `framework`, and explicit operator source-label command construction.
+- Formatting: `pnpm exec prettier --write packages/mosaic/src/commands/fleet.ts packages/mosaic/src/commands/fleet.spec.ts docs/guides/fleet-local-canary.md docs/scratchpads/2026-06-20-fleet-release-hardening.md`.
+- Targeted tests: `pnpm --filter @mosaicstack/mosaic test -- src/commands/fleet.spec.ts src/cli-smoke.spec.ts` passed with 49 tests.
+- Typecheck: `pnpm typecheck` passed.
+- Lint: `pnpm lint` passed.
+- Package dry-run: `npm pack --dry-run --json` from `packages/mosaic` included `framework/fleet`, `framework/systemd/user`, `framework/tools/fleet/start-agent-session.sh`, and `framework/tools/tmux/{agent-send.sh,send-message.sh}`.
+- Review: `~/.config/mosaic/tools/codex/codex-code-review.sh --uncommitted` approved the supplied diff with no findings; the review tool noted its read-only sandbox could not inspect files directly.
diff --git a/packages/mosaic/src/commands/fleet.spec.ts b/packages/mosaic/src/commands/fleet.spec.ts
index 4e92be2..c4ec4c3 100644
--- a/packages/mosaic/src/commands/fleet.spec.ts
+++ b/packages/mosaic/src/commands/fleet.spec.ts
@@ -7,6 +7,7 @@ import {
   buildAgentSendCommand,
   buildFleetServiceCommand,
   generateAgentEnv,
+  getDefaultOperatorSourceLabel,
   getRosterAgent,
   loadFleetRoster,
   registerFleetCommand,
@@ -229,10 +230,14 @@ describe('fleet command construction', () => {
 
   it('builds socket-scoped agent send commands', () => {
     const paths = resolveFleetPaths('/home/test/.config/mosaic');
-    expect(buildAgentSendCommand(paths, 'coder0', 'hello', 'mosaic-factory')).toEqual([
+    expect(
+      buildAgentSendCommand(paths, 'coder0', 'hello', 'mosaic-factory', 'operator:mosaic-cli'),
+    ).toEqual([
       '/home/test/.config/mosaic/tools/tmux/agent-send.sh',
       '-L',
       'mosaic-factory',
+      '-S',
+      'operator:mosaic-cli',
       '-s',
       'coder0',
       '-m',
@@ -255,6 +260,36 @@ describe('fleet command construction', () => {
     expect(calls).toEqual([['systemctl', '--user', 'status', 'mosaic-tmux-holder.service']]);
   });
 
+  it('verifies liveness with tmux has-session and does not trust systemd active exited', async () => {
+    const home = await tempDir();
+    const rosterPath = join(home, 'fleet', 'roster.yaml');
+    await mkdir(join(home, 'fleet'), { recursive: true });
+    await writeFile(
+      rosterPath,
+      ['version: 1', 'transport: tmux', 'agents:', '  - name: coder0', '    runtime: codex'].join(
+        '\n',
+      ),
+    );
+    const calls: string[][] = [];
+    const runner: CommandRunner = async (command, args) => {
+      calls.push([command, ...args]);
+      return { stdout: 'active (exited)\n', stderr: '', exitCode: 0 };
+    };
+    const program = new Command();
+    program.exitOverride();
+    registerFleetCommand(program, { runner, mosaicHome: home });
+
+    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'],
+      ]);
+    } finally {
+      await rm(home, { recursive: true, force: true });
+    }
+  });
+
   it('writes init output to the explicit roster path', async () => {
     const home = await tempDir();
     const rosterPath = join(home, 'custom', 'roster.yaml');
@@ -536,6 +571,104 @@ describe('fleet command construction', () => {
     }
   });
 
+  it('passes a deterministic operator source label for agent sends', async () => {
+    const home = await tempDir();
+    await mkdir(join(home, 'fleet'), { recursive: true });
+    await writeFile(
+      join(home, 'fleet', 'roster.yaml'),
+      JSON.stringify({
+        version: 1,
+        transport: 'tmux',
+        agents: [{ name: 'json-agent', runtime: 'pi' }],
+      }),
+    );
+    const calls: string[][] = [];
+    const runner: CommandRunner = async (command, args) => {
+      calls.push([command, ...args]);
+      return { stdout: '', stderr: '', exitCode: 0 };
+    };
+    const program = new Command();
+    program.exitOverride();
+    registerAgentCommand(program, { runner, mosaicHome: home });
+
+    try {
+      await program.parseAsync([
+        'node',
+        'mosaic',
+        'agent',
+        'send',
+        'json-agent',
+        '--message',
+        'status check',
+      ]);
+      expect(calls).toEqual([
+        [
+          join(home, 'tools', 'tmux', 'agent-send.sh'),
+          '-L',
+          'mosaic-factory',
+          '-S',
+          getDefaultOperatorSourceLabel(),
+          '-s',
+          'json-agent',
+          '-m',
+          'status check',
+        ],
+      ]);
+    } finally {
+      await rm(home, { recursive: true, force: true });
+    }
+  });
+
+  it('allows agent sends to override the source label explicitly', async () => {
+    const home = await tempDir();
+    await mkdir(join(home, 'fleet'), { recursive: true });
+    await writeFile(
+      join(home, 'fleet', 'roster.yaml'),
+      JSON.stringify({
+        version: 1,
+        transport: 'tmux',
+        agents: [{ name: 'coder0', runtime: 'codex' }],
+      }),
+    );
+    const calls: string[][] = [];
+    const runner: CommandRunner = async (command, args) => {
+      calls.push([command, ...args]);
+      return { stdout: '', stderr: '', exitCode: 0 };
+    };
+    const program = new Command();
+    program.exitOverride();
+    registerAgentCommand(program, { runner, mosaicHome: home });
+
+    try {
+      await program.parseAsync([
+        'node',
+        'mosaic',
+        'agent',
+        'send',
+        'coder0',
+        '--message',
+        'handoff',
+        '--source-label',
+        'lead:manual',
+      ]);
+      expect(calls).toEqual([
+        [
+          join(home, 'tools', 'tmux', 'agent-send.sh'),
+          '-L',
+          'mosaic-factory',
+          '-S',
+          'lead:manual',
+          '-s',
+          'coder0',
+          '-m',
+          'handoff',
+        ],
+      ]);
+    } finally {
+      await rm(home, { recursive: true, force: true });
+    }
+  });
+
   it('rejects agent status typos before invoking the runner', async () => {
     const home = await tempDir();
     const rosterPath = join(home, 'fleet', 'roster.yaml');
@@ -560,4 +693,14 @@ describe('fleet command construction', () => {
       await rm(home, { recursive: true, force: true });
     }
   });
+
+  it('keeps fleet framework assets in the published package file list', async () => {
+    const packageJson = JSON.parse(
+      await readFile(resolve(process.cwd(), 'package.json'), 'utf8'),
+    ) as {
+      files?: string[];
+    };
+
+    expect(packageJson.files).toEqual(expect.arrayContaining(['dist', 'framework']));
+  });
 });
diff --git a/packages/mosaic/src/commands/fleet.ts b/packages/mosaic/src/commands/fleet.ts
index 35a1dcb..3eb8f61 100644
--- a/packages/mosaic/src/commands/fleet.ts
+++ b/packages/mosaic/src/commands/fleet.ts
@@ -1,6 +1,6 @@
 import { constants } from 'node:fs';
 import { access, copyFile, mkdir, readFile, writeFile } from 'node:fs/promises';
-import { homedir } from 'node:os';
+import { homedir, hostname } from 'node:os';
 import { dirname, join, resolve } from 'node:path';
 import { fileURLToPath } from 'node:url';
 import { spawn } from 'node:child_process';
@@ -158,11 +158,14 @@ export function buildAgentSendCommand(
   agentName: string,
   message: string,
   socketName = DEFAULT_SOCKET_NAME,
+  sourceLabel = getDefaultOperatorSourceLabel(),
 ): string[] {
   return [
     join(paths.tmuxToolsDir, 'agent-send.sh'),
     '-L',
     socketName,
+    '-S',
+    sourceLabel,
     '-s',
     agentName,
     '-m',
@@ -170,6 +173,11 @@ export function buildAgentSendCommand(
   ];
 }
 
+export function getDefaultOperatorSourceLabel(): string {
+  const shortHostname = hostname().split('.')[0] || 'localhost';
+  return `${shortHostname}:operator`;
+}
+
 export function buildAgentResetCommand(
   paths: FleetPaths,
   agentName: string,
@@ -384,15 +392,22 @@ export function registerFleetAgentCommands(
     .command('send <agent>')
     .description('Send a message to a local fleet agent')
     .requiredOption('--message <text>', 'Message text')
-    .action(async (agent: string, opts: { message: string }) => {
-      const roster = await loadRosterFromAgentCommand(agentCommand, deps.mosaicHome);
-      getRosterAgent(roster, agent);
-      const paths = resolveFleetPaths(resolveMosaicHomeFromCommand(agentCommand, deps.mosaicHome));
-      await runChecked(
-        runner,
-        buildAgentSendCommand(paths, agent, opts.message, roster.tmux.socketName),
-      );
-    });
+    .option('--source-label <label>', 'Source label for the message preamble')
+    .option('--source <label>', 'Alias for --source-label')
+    .action(
+      async (agent: string, opts: { message: string; sourceLabel?: string; source?: string }) => {
+        const roster = await loadRosterFromAgentCommand(agentCommand, deps.mosaicHome);
+        getRosterAgent(roster, agent);
+        const paths = resolveFleetPaths(
+          resolveMosaicHomeFromCommand(agentCommand, deps.mosaicHome),
+        );
+        const sourceLabel = opts.sourceLabel ?? opts.source ?? getDefaultOperatorSourceLabel();
+        await runChecked(
+          runner,
+          buildAgentSendCommand(paths, agent, opts.message, roster.tmux.socketName, sourceLabel),
+        );
+      },
+    );
 
   agentCommand
     .command('reset <agent>')