i098 · Nov 12, 2026 · Nov 11, 2026 · Nov 11, 2026 · Nov 11, 2026 · Nov 12, 2026
diff --git a/blueprint/ansible/group_vars/all/base.yml b/blueprint/ansible/group_vars/all/base.yml
@@ -57,7 +57,7 @@ crewship_omp_root: "{{ crewship_share_dir }}/omp/{{ crewship_omp_version }}"
 # installer re-points `current` at that release, so this text, and with it the
 # Herdr unit and the profile block, stays the same between releases. Exported
 # to the managed shell environment and to the Herdr service environment.
-crewship_chrome_devtools_mcp_path: "{{ crewship_share_dir }}/chrome-devtools-mcp/current/node_modules/chrome-devtools-mcp/build/src/bin/chrome-devtools-mcp.js"
+crewship_chrome_devtools_mcp_path: "{{ crewship_share_dir }}/chrome-devtools-mcp/current/node_modules/chrome-devtools-mcp/out/Default/gen/src/bin/chrome-devtools-mcp.js"
 # Environment shared by the interactive shell profile and the Herdr unit.
 # Consumed only when the agents profile is on, because the npm set that
 # provides the MCP entrypoint is installed by `--npm`. Nothing here may be a

diff --git a/blueprint/ansible/tasks/data_dir.yml b/blueprint/ansible/tasks/data_dir.yml
@@ -0,0 +1,43 @@
+---
+# `data_dir: auto` (the default) keeps the disk the managed bulk defaults already name, and fails if
+# that disk is no longer mounted. Otherwise it takes the largest mounted data disk, unless the
+# account already has ~/.treehouse (legacy layout). `data_dir: ""` always opts out.
+- name: Read the data disk recorded by an earlier apply
+  ansible.builtin.slurp:
+    src: "{{ crewship_bulk_defaults_path }}"
+  register: crewship_recorded_bulk
+  failed_when: false
+
+- name: Look for a legacy worktree pool under the home
+  ansible.builtin.stat:
+    path: "{{ crewship_cfg.home }}/.treehouse"
+  register: crewship_legacy_pools
+
+- name: Resolve the automatic data disk
+  ansible.builtin.set_fact:
+    crewship_recorded_data_dir: >-
+      {{ (crewship_recorded_bulk.content | default('') | b64decode)
+         | regex_search('(?m)^TMPDIR=\$\{TMPDIR:-(/.*)/tmp\}$', '\1') | default([''], true) | first }}
+    crewship_data_candidate: >-
+      {{ ansible_facts.mounts
+         | selectattr('device', 'match', '^/dev/(?!loop)')
+         | selectattr('fstype', 'in', ['ext4', 'xfs', 'btrfs'])
+         | selectattr('size_total', 'ge', 107374182400)
+         | selectattr('mount', 'match', '^(?!/(boot|snap|usr|var|home|media|run|tmp|etc)(/|$))/[A-Za-z0-9_-][A-Za-z0-9_./-]*$')
+         | sort(attribute='size_total') | map(attribute='mount') | list | last | default('') }}
+
+- name: Require the recorded data disk to stay mounted
+  ansible.builtin.assert:
+    that: crewship_recorded_data_dir in (ansible_facts.mounts | map(attribute='mount') | list)
+    fail_msg: >-
+      The data disk {{ crewship_recorded_data_dir }} recorded by an earlier apply is not mounted.
+      Mount it, or set crewship.data_dir explicitly.
+    quiet: true
+  when: crewship_recorded_data_dir | length > 0
+
+- name: Apply the automatic data disk
+  ansible.builtin.set_fact:
+    crewship_cfg: >-
+      {{ crewship_cfg | combine({'data_dir': (
+           crewship_recorded_data_dir if crewship_recorded_data_dir | length > 0
+           else (crewship_data_candidate if not crewship_legacy_pools.stat.exists else '')) }) }}
diff --git a/blueprint/ansible/tasks/preflight.yml b/blueprint/ansible/tasks/preflight.yml
@@ -6,6 +6,10 @@
   ansible.builtin.set_fact:
     crewship_cfg: "{{ crewship_cfg }}"
 
+- name: Resolve the automatic data disk
+  ansible.builtin.import_tasks: data_dir.yml
+  when: crewship_cfg.data_dir == 'auto'
+
 - name: Assert the configuration document matches the contract
   ansible.builtin.assert:
     that:

diff --git a/blueprint/config/default.yml b/blueprint/config/default.yml
@@ -6,8 +6,9 @@ crewship:
   start_services: true
   enable_linger: true
   # Existing mounted data path for new bulk defaults and Docker's data root.
+  # `auto` uses the largest mounted data disk (100 GiB or more) on a fresh account; "" keeps the system disk.
   # See docs/configuration.md#data-disk for path requirements and storage behavior.
-  data_dir: ""
+  data_dir: auto
   # A new host gets the core only: agents and firstmate. Every other profile is
   # opt-in (docs/default-config.md).
   profiles:

diff --git a/blueprint/containers/crewship.container.yml b/blueprint/containers/crewship.container.yml
@@ -33,6 +33,7 @@ crewship:
   workspace: /home/coder/Dev
   start_services: false
   enable_linger: false
+  data_dir: ""
   profiles:
     agents: true
     development: true

diff --git a/blueprint/schemas/crewship.schema.json b/blueprint/schemas/crewship.schema.json
@@ -31,7 +31,7 @@
         },
         "data_dir": {
           "type": "string",
-          "pattern": "^(/[A-Za-z0-9_-][A-Za-z0-9_.-]*)*$"
+          "pattern": "^(auto|(/[A-Za-z0-9_-][A-Za-z0-9_.-]*)*)$"
         },
         "usage": {
           "type": "object",

diff --git a/changelog.d/1339.added.md b/changelog.d/1339.added.md
@@ -0,0 +1 @@
+Resolve `crewship.data_dir: auto` (the new default) to the largest mounted data disk of 100 GiB or more on a fresh account, so pools and tool caches start off the system disk. Accounts with an existing `~/.treehouse` keep the legacy layout; `data_dir: ""` opts out.
diff --git a/docs/configuration.md b/docs/configuration.md
@@ -160,7 +160,7 @@ crewship:
   workspace: /home/coder/Dev
   start_services: true
   enable_linger: true
-  data_dir: ""            # See Data disk below for path requirements and storage behavior
+  data_dir: auto         # See Data disk below for path requirements and storage behavior
   profiles:
     agents: true          # Chrome autoprune, AXI tools, browser defaults
     development: false    # Rust, build tools
@@ -402,7 +402,11 @@ The limit on the number of Firstmate homes is a Firstmate setting; Crewship does
 ## Data disk
 
 Set `data_dir` to an existing absolute path on a mounted data disk.
-On a fresh account, the default `""` keeps the legacy storage layout and writes no bulk data-location defaults (the [Worktree cap](#worktree-cap) is still written).
+The default `auto` picks the largest mounted ext4, xfs, or btrfs disk of 100 GiB or more outside `/`, `/boot`, `/snap`, `/usr`, `/var`, `/home`, `/media`, `/run`, `/tmp`, and `/etc`.
+It applies only to a fresh account: an account that already has `~/.treehouse` keeps the legacy layout, so Docker data and existing pools never move, unless the managed bulk defaults already name a data disk.
+Once named, that disk stays: a later apply keeps it even when a larger disk appears, and fails when it is no longer mounted.
+Set `""` to keep the legacy storage layout; it writes no bulk data-location defaults (the [Worktree cap](#worktree-cap) is still written).
+Without a qualifying disk, `auto` behaves like `""`.
 Clearing `data_dir` removes the managed Bash block and user-manager file.
 Apply and preview tolerate a missing `.bashrc`.
 Native tool keys and existing data remain unchanged.

diff --git a/docs/features.md b/docs/features.md
@@ -14,7 +14,7 @@ These features turn one server into a self-hosted AI coding agent server where y
 - [Self-hosted Forgejo](forgejo.md): a loopback git forge for agent pushes, with nightly dumps, a GitHub feature-branch push and the no-mistakes forge profile (opt-in)
 - [Configuration](configuration.md): `.local/host.yml`, the one file that describes a host
 - [Capacity and auto pruners](capacity.md): host sizing per lane count, and cleanup timers
-- [Data disk](configuration.md#data-disk) (opt-in)
+- [Data disk](configuration.md#data-disk)
 - [Model usage metadata and SigNoz export](usage.md) (opt-in)
 - [Private token-saving suggestions](usage.md#optional-reader-installation): a read-only report with daily delivery after a proven manual cycle (opt-in)
 - [Self-hosted CI pool](ci-pool.md): GitHub Actions runners, one job per fresh container; deprecated, replaced by runner-up (opt-in)

diff --git a/tests/test_ansible_deprecations.py b/tests/test_ansible_deprecations.py
@@ -37,7 +37,7 @@ def apply(tmp_path, tasks, variables, *options, injected_facts="True"):
 @pytest.mark.parametrize("injected_facts", ["True", "False"])
 def test_platform_and_account_use_namespaced_facts(tmp_path, injected_facts):
     preflight = yaml.safe_load((ANSIBLE / "tasks/preflight.yml").read_text())
-    tasks = preflight[1:3] + [preflight[-1]]
+    tasks = preflight[2:4] + [preflight[-1]]
     tasks.append({"ansible.builtin.assert": {"that": [
         "crewship_platform in ['linux-x86_64', 'linux-aarch64']",
         "crewship_deb_arch in ['amd64', 'arm64']",

diff --git a/tests/test_chart.py b/tests/test_chart.py
@@ -362,6 +362,7 @@ def test_chart_creates_only_missing_directories(tmp_path, existing_home, profile
         "crewship_repo": str(ROOT), "crewship_blueprint": str(ROOT / "blueprint"),
         "crewship": {
             "home": str(home), "workspace": str(home / "Dev"), "user": getpass.getuser(),
+            "data_dir": "",
             "profiles": {"fleet_guards": False, "fleet_browsers": False, "firstmate": False,
                          **profiles},
             "start_services": False,

diff --git a/tests/test_configuration.py b/tests/test_configuration.py
@@ -262,6 +262,12 @@ def test_data_dir_must_be_a_plain_absolute_path(configuration, data_dir):
         ship.validate_config(configuration)
 
 
+@pytest.mark.parametrize("data_dir", ["auto", "", "/mnt/data"])
+def test_data_dir_accepts_auto_empty_or_a_path(configuration, data_dir):
+    configuration["crewship"]["data_dir"] = data_dir
+    ship.validate_config(configuration)
+
+
 def test_bad_polling_window_cannot_disable_idle_accrual(configuration):
     configuration["crewship"]["browser_prune"]["max_gap_seconds"] = 120
     with pytest.raises(ValueError, match="observation intervals"):
@@ -1075,7 +1081,7 @@ def test_a_new_chrome_devtools_mcp_release_leaves_the_managed_environment_unchan
     before = _managed_environment(tmp_path, True, "1.0.0")
     assert _managed_environment(tmp_path, True, "1.1.0") == before
     assert before["CHROME_DEVTOOLS_AXI_MCP_PATH"].endswith(
-        "/chrome-devtools-mcp/current/node_modules/chrome-devtools-mcp/build/src/bin/chrome-devtools-mcp.js"
+        "/chrome-devtools-mcp/current/node_modules/chrome-devtools-mcp/out/Default/gen/src/bin/chrome-devtools-mcp.js"
     )
 
 
@@ -1141,7 +1147,7 @@ def test_board_environment_reaches_new_shells_and_agents_and_is_removed_on_opt_o
         assert shell.stdout.splitlines() == [
             socket if board is not None else "unset",
             f"{tmp_path}/.local/share/crewship/chrome-devtools-mcp/current/"
-            "node_modules/chrome-devtools-mcp/build/src/bin/chrome-devtools-mcp.js",
+            "node_modules/chrome-devtools-mcp/out/Default/gen/src/bin/chrome-devtools-mcp.js",
         ]
         for line in (
             'Environment="FM_OMP_ARM_READY_TIMEOUT_MS=45000"',
@@ -1852,3 +1858,53 @@ def service():
     finally:
         if pid_file.exists():
             os.kill(int(pid_file.read_text()), signal.SIGKILL)
+
+
+GIB = 1024 ** 3
+
+
+def _mount(path, size_gib, fstype="ext4", device=None):
+    return {"mount": path, "size_total": size_gib * GIB, "fstype": fstype,
+            "device": device or "/dev/sd" + path.strip("/").replace("/", "")[:2]}
+
+
+RECORD = "TMPDIR=${TMPDIR:-/srv/old/tmp}\n"
+
+
+@pytest.mark.parametrize("mounts,legacy,record,expected", [
+    ([_mount("/", 900), _mount("/srv/a", 200), _mount("/srv/b", 400)], False, "", "/srv/b"),
+    ([_mount("/", 900), _mount("/home", 500), _mount("/media/usb", 500), _mount("/var", 500),
+      _mount("/mnt/small", 50), _mount("/mnt/nfs", 500, fstype="nfs"),
+      _mount("/mnt/loop", 500, device="/dev/loop3")], False, "", ""),
+    ([_mount("/mnt/data", 400)], True, "", ""),
+    ([_mount("/mnt/data", 400)], True, RECORD, None),
+    ([_mount("/srv/old", 200), _mount("/srv/bigger", 800)], False, RECORD, "/srv/old"),
+    ([_mount("/srv/bigger", 800)], False, RECORD, None),
+])
+def test_auto_data_dir_resolution(tmp_path, mounts, legacy, record, expected):
+    home = tmp_path / "home"
+    (home / ".treehouse" if legacy else home).mkdir(parents=True)
+    bulk = home / "bulk.conf"
+    if record:
+        bulk.write_text(record)
+    playbook = tmp_path / "play.yml"
+    playbook.write_text(yaml.safe_dump([{
+        "hosts": "localhost", "connection": "local", "gather_facts": False,
+        "tasks": [
+            {"ansible.builtin.set_fact": {"ansible_facts": {"mounts": mounts},
+                                          "crewship_bulk_defaults_path": str(bulk),
+                                          "crewship_cfg": {"home": str(home), "data_dir": "auto"}}},
+            {"ansible.builtin.include_tasks": str(ROOT / "blueprint/ansible/tasks/data_dir.yml")},
+            {"ansible.builtin.copy": {"dest": str(tmp_path / "out"),
+                                      "content": "{{ crewship_cfg.data_dir }}"}},
+        ],
+    }]))
+    result = subprocess.run(
+        [str(Path(sys.executable).parent / "ansible-playbook"), "-i", "localhost,", str(playbook)],
+        capture_output=True, text=True,
+    )
+    if expected is None:
+        assert result.returncode != 0 and "not mounted" in result.stdout
+        return
+    assert result.returncode == 0, result.stdout + result.stderr
+    assert (tmp_path / "out").read_text() == expected
diff --git a/tests/test_removed_backend.py b/tests/test_removed_backend.py
@@ -115,7 +115,7 @@ def inspect():
         document = {
             "ansible_become": False, "crewship_repo": str(ROOT), "crewship_blueprint": str(ROOT / "blueprint"),
             "crewship_group": "root", "crewship_become_target": False,
-            "crewship": {"home": str(home), "user": "root", "start_services": False,
+            "crewship": {"home": str(home), "user": "root", "start_services": False, "data_dir": "",
                          "profiles": {"fleet_guards": True}},
         }
         assert ship.provision(document, False) == 0
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		Resolve `crewship.data_dir: auto` (the new default) to the largest mounted data disk of 100 GiB or more on a fresh account, so pools and tool caches start off the system disk. Accounts with an existing `~/.treehouse` keep the legacy layout; `data_dir: ""` opts out.