Model systemd-oomd as a dependency (pure .dag, no live execution): extdeps/systemd unit-management interface plus oomd config surface, apt install-as-effect, and a gunbc install Realization that grounds OomdEnforced from a verify/show-effective read

dsl/extdeps/os/oomd.dag

@@ -0,0 +1,79 @@
+module extdeps.os.oomd
+
+import std.types { NonEmptyStr, String, FilePath, Bool }
+import std.measure { Second, second, Percent, percent }
+
+import extdeps.external_authority { ExternalAuthority }
+import extdeps.uri { Uri, Https }
+
+data extdeps_external_authority_anchor: ExternalAuthority = ExternalAuthority {
+  uri: Uri {
+    scheme: Https
+    locator: "www.freedesktop.org/software/systemd/man/latest/oomd.conf.html"
+  }
+}
+
+data oomd_surface_doc: String = "systemd-oomd is the userspace OOM manager: it watches cgroup memory pressure (PSI) and swap usage and kills the worst-offending cgroup BEFORE the kernel OOM killer / OOM livelock fires. That livelock is the srv2-reboot vector. This module models what oomd PROVIDES (the config knobs it reads and the eviction backstop it gives), with the real key names from oomd.conf(5) and systemd.resource-control(5). It sits beside extdeps.os.systemd / extdeps.os.systemctl under the one systemd home. WHICH cgroups to protect at WHICH thresholds is workflow policy (gunbc), not a fact about systemd-oomd."
+
+data systemd_oomd_unit: NonEmptyStr = "systemd-oomd.service"
+data oomd_conf_path: FilePath = "/etc/systemd/oomd.conf"
+data oomd_conf_dropin_dir: FilePath = "/etc/systemd/oomd.conf.d"
+
+type ManagedOomAction
+  = ManagedOomAuto
+  | ManagedOomKill
+
+type OomdGlobalConfig {
+  swap_used_limit: Percent
+  default_memory_pressure_limit: Percent
+  default_memory_pressure_duration: Second
+}
+
+data oomd_default_global_config: OomdGlobalConfig = OomdGlobalConfig {
+  swap_used_limit: percent(90),
+  default_memory_pressure_limit: percent(60),
+  default_memory_pressure_duration: second(30),
+}
+
+type UnitManagedOomPolicy {
+  scope_unit: NonEmptyStr
+  managed_oom_swap: ManagedOomAction
+  managed_oom_memory_pressure: ManagedOomAction
+  managed_oom_memory_pressure_limit: Percent?
+  managed_oom_memory_pressure_duration: Second?
+}
+
+data oomd_managed_oom_memory_pressure_property: NonEmptyStr = "ManagedOOMMemoryPressure"
+data oomd_managed_oom_memory_pressure_limit_property: NonEmptyStr = "ManagedOOMMemoryPressureLimit"
+data oomd_managed_oom_swap_property: NonEmptyStr = "ManagedOOMSwap"
+
+data oomd_managed_value_kill: NonEmptyStr = "kill"
+data oomd_managed_value_auto: NonEmptyStr = "auto"
+
+fn managed_oom_action_value(a: ManagedOomAction) -> NonEmptyStr {
+  match a {
+    ManagedOomKill => oomd_managed_value_kill
+    ManagedOomAuto => oomd_managed_value_auto
+  }
+}
+
+type OomdDropIn {
+  target_unit: NonEmptyStr
+  policy: UnitManagedOomPolicy
+}
+
+service systemd.Oomctl {
+  operation Dump {
+    input {}
+    output {
+      stdout: String from "stdout"
+      success: Bool from "exit_success"
+    }
+    readonly
+    transport shell { argv: ["oomctl", "dump"] }
+    exit {
+      0 => Unit
+      nonzero => String "oomctl dump failed (systemd-oomd not running?)"
+    }
+  }
+}

dsl/extdeps/os/systemctl.dag

@@ -0,0 +1,109 @@
+module extdeps.os.systemctl
+
+import std.types { NonEmptyStr, String, List, Bool, Int }
+
+import extdeps.external_authority { ExternalAuthority }
+import extdeps.uri { Uri, Https }
+
+data extdeps_external_authority_anchor: ExternalAuthority = ExternalAuthority {
+  uri: Uri {
+    scheme: Https
+    locator: "www.freedesktop.org/software/systemd/man/latest/systemctl.html"
+  }
+}
+
+data systemctl_interface_doc: String = "systemd's service-manager control surface (systemctl). The active-state enum authority lives in extdeps.os.systemd (SystemdUnitActiveState); this module adds the operation shapes and the enablement-state enum, reusing that single authority rather than re-minting it. The operation shapes (inputs -> outputs, exit/error semantics) are what extdeps owns; the unit a caller acts on is always a parameter, never a literal baked into argv (a baked unit name would be business policy leaking down from the workflow layer, DESIGN section 3 fact c). The show-effective read (ShowProperty) reads back the LIVE resolved value, the only sound basis for grounding an enforcement predicate (DESIGN section 5: verify the realization, not the declaration). Names and exit semantics from systemctl(1)."
+
+type UnitFileState
+  = UnitEnabled
+  | UnitEnabledRuntime
+  | UnitLinked
+  | UnitMasked
+  | UnitStatic
+  | UnitDisabled
+  | UnitIndirect
+  | UnitGenerated
+  | UnitTransient
+  | UnitBad
+
+service systemd.Systemctl {
+  operation Enable {
+    input { unit: NonEmptyStr }
+    output {
+      success: Bool from "exit_success"
+      stdout: String from "stdout"
+      stderr: String from "stderr"
+    }
+    transport shell { argv: ["systemctl", "enable", "{unit}"] }
+    exit {
+      0 => Unit
+      nonzero => String "systemctl enable failed"
+    }
+  }
+
+  operation Start {
+    input { unit: NonEmptyStr }
+    output {
+      success: Bool from "exit_success"
+      stdout: String from "stdout"
+      stderr: String from "stderr"
+    }
+    transport shell { argv: ["systemctl", "start", "{unit}"] }
+    exit {
+      0 => Unit
+      nonzero => String "systemctl start failed"
+    }
+  }
+
+  operation SetProperty {
+    input { unit: NonEmptyStr, property: NonEmptyStr, value: NonEmptyStr }
+    output {
+      success: Bool from "exit_success"
+      stderr: String from "stderr"
+    }
+    transport shell { argv: ["systemctl", "set-property", "{unit}", "{property}={value}"] }
+    exit {
+      0 => Unit
+      nonzero => String "systemctl set-property failed"
+    }
+  }
+
+  operation DaemonReload {
+    input {}
+    output {
+      success: Bool from "exit_success"
+      stderr: String from "stderr"
+    }
+    transport shell { argv: ["systemctl", "daemon-reload"] }
+    exit {
+      0 => Unit
+      nonzero => String "systemctl daemon-reload failed"
+    }
+  }
+
+  operation IsActive {
+    input { unit: NonEmptyStr }
+    output {
+      state: String from "stdout"
+      active: Bool from "exit_success"
+    }
+    readonly
+    transport shell { argv: ["systemctl", "is-active", "{unit}"] }
+    exit {
+      0 => Unit
+      3 => Unit "unit is not active"
+      nonzero => String "systemctl is-active failed"
+    }
+  }
+
+  operation ShowProperty {
+    input { unit: NonEmptyStr, property: NonEmptyStr }
+    output { value: String from "stdout" }
+    readonly
+    transport shell { argv: ["systemctl", "show", "{unit}", "--property={property}", "--value"] }
+    exit {
+      0 => Unit
+      nonzero => String "systemctl show failed"
+    }
+  }
+}

dsl/extdeps/package_managers/apt.dag

@@ -1,6 +1,6 @@
 module extdeps.apt
 
-import std.types { NonEmptyStr, FilePath }
+import std.types { NonEmptyStr, FilePath, String, Bool }
 
 import extdeps.external_authority { ExternalAuthority }
 import extdeps.uri { Uri, Https }
@@ -18,7 +18,28 @@ data apt_local_bin_dir: FilePath = "/usr/local/bin"
 data package_coreutils: NonEmptyStr = "coreutils"     
 data package_grep: NonEmptyStr = "grep"               
 data package_diffutils: NonEmptyStr = "diffutils"     
-data package_cargo: NonEmptyStr = "cargo"             
-data package_rustc: NonEmptyStr = "rustc"             
+data package_cargo: NonEmptyStr = "cargo"
+data package_rustc: NonEmptyStr = "rustc"
+
+data package_systemd_oomd_defaults: NonEmptyStr = "systemd-oomd-defaults"
 
 data apt_man_url: NonEmptyStr = "https://manpages.debian.org/testing/apt/apt.8.en.html"
+
+data apt_install_effect_doc: String = "Install as an effect (non-readonly operation). The package is a PARAMETER reusing the existing package-name concept (package_* data below); apt owns the install interface shape, WHICH package is workflow policy supplied by the caller, so the argv carries no business literal (DESIGN section 3). Exit codes from apt-get(8): 100 covers a held dpkg/apt lock, fetch error, or unmet dependency."
+
+service apt.PackageManager {
+  operation Install {
+    input { package: NonEmptyStr }
+    output {
+      success: Bool from "exit_success"
+      stdout: String from "stdout"
+      stderr: String from "stderr"
+    }
+    transport shell { argv: ["apt-get", "install", "--yes", "{package}"] }
+    exit {
+      0 => Unit
+      100 => String "apt-get install failed (lock held, fetch error, or unmet dependency)"
+      nonzero => String "apt-get install failed"
+    }
+  }
+}