-- What a node's memory looks like with NO phase VMs on it.
--
-- `vm_placement::capacity_of` used to infer the host's own footprint by
-- subtracting the VMs' full claim from observed usage. That is right only when
-- the VMs have actually consumed what they claimed. A VM booted seconds ago
-- holds ~1 GiB of its 8 GiB, so the subtraction goes negative, hits the 2 GiB
-- floor, and hands back memory the host is really using.
--
-- Measured on morpheus (31757 MiB total, 4314 MiB idle) with 2 VMs committed:
-- the inferred baseline collapsed from 4314 to 2048, which freed 2266 MiB —
-- just enough to fit a 3rd VM into a 2-slot node. The capacity harness caught
-- it as "morpheus peaked at 3 concurrent VM(s) with only 2 slot(s)".
--
-- So remember the baseline instead of re-deriving it: it is only honestly
-- observable when the node has nothing committed, and that is exactly when it
-- is recorded.
ALTER TABLE nodes ADD COLUMN IF NOT EXISTS mem_baseline_mib BIGINT;

COMMENT ON COLUMN nodes.mem_baseline_mib IS
  'Memory in use with zero phase VMs committed, sampled by vm_placement::survey. NULL until first observed idle.';