-- Migration: agent_atom_registry — add parent_atom_id (reference children)
--
-- A skill's deep material (.claude/skills/**/references/*.md) is now ingested as
-- hidden child rows: one row per reference file, parent_atom_id pointing at the
-- owning SKILL.md atom. NULL = a top-level skill; set = a reference belonging to
-- that skill.
--
-- Children are excluded from every catalog (the chat metadata index, the MCP
-- skill list, the composer atom index, the /settings/agent-skills panel) via a
-- `parent_atom_id IS NULL` filter. They reach the model only through an explicit
-- gnubok_load_skill(<child id>) call, made after the parent SKILL.md is loaded
-- and its "Loadable references" footer is visible — progressive disclosure that
-- keeps reference bytes out of context until a question actually needs them.
--
-- Bodies for both parents and children are (re)seeded by the next migration,
-- generated by scripts/generate-skill-bodies.ts. RLS is unchanged: the column
-- lives on an already-protected table (read-only to authenticated, service-role
-- writes), so it inherits the existing policies.

ALTER TABLE public.agent_atom_registry
  ADD COLUMN IF NOT EXISTS parent_atom_id text
    REFERENCES public.agent_atom_registry(id) ON DELETE CASCADE;

-- Serves both access patterns: catalog reads (`parent_atom_id IS NULL`) and
-- "load the references for skill X" (equality on parent_atom_id).
CREATE INDEX IF NOT EXISTS idx_agent_atom_registry_parent
  ON public.agent_atom_registry (parent_atom_id);

NOTIFY pgrst, 'reload schema';