-- Slice 3.5a — skills catalog (extends the legacy skills tables from
-- 0001_init.sql rather than duplicating them).
--
-- The two-layer model:
--   Skills teach agents HOW to think about a problem (static, curated
--   markdown, no auth, no observability of the call itself).
--   MCP servers give agents the ABILITY to act (live, governed, audited).
--
-- Delivery: `clawmates_skills` MCP server (Slice 3.5b) exposes skills as
-- MCP resources. Some skills are pinned (always injected into context);
-- the rest are discovered on-demand via resources/list + read lazily.
--
-- This migration keeps the legacy `skills` + `installed_skills` tables
-- intact (they already ship a workspace-scoped catalog with body_md-
-- shaped content) and adds the missing structural pieces:
--   - richer typing columns on `skills` (name, when_to_use, tags,
--     source_kind, current_version, updated_at)
--   - `skill_versions` for level-up promotions + rollback
--   - `template_role_skills` binding skills to team-template roles
--     with an optional pin_in_context flag
--   - `agent_skills_ext` for per-agent overrides (level-up adds
--     personal learnings that don't yet merit the template default set)
--
-- `agent_skills_ext` sits alongside `installed_skills` — the latter
-- is the "user manually installed this" tracker; the new table is the
-- level-up overlay (added, pinned, promoted). Slice 9 folds them.

-- ── Extend `skills` ──────────────────────────────────────────────

ALTER TABLE skills
    ADD COLUMN name            TEXT,
    ADD COLUMN when_to_use     TEXT,
    ADD COLUMN tags            TEXT[] NOT NULL DEFAULT '{}',
    ADD COLUMN source_kind     TEXT   NOT NULL DEFAULT 'hand_authored',
    ADD COLUMN current_version INT    NOT NULL DEFAULT 1,
    ADD COLUMN updated_at      TIMESTAMPTZ NOT NULL DEFAULT now();

-- Backfill `name` from `title` for existing rows so the new UNIQUE
-- constraint doesn't reject them.
UPDATE skills SET name = title WHERE name IS NULL;
ALTER TABLE skills ALTER COLUMN name SET NOT NULL;

-- One skill per (workspace scope, name). NULL workspace = builtin/global.
CREATE UNIQUE INDEX skills_name_uniq
    ON skills (COALESCE(workspace_id, '00000000-0000-0000-0000-000000000000'::uuid), name);
CREATE INDEX skills_source_idx    ON skills (source_kind);
CREATE INDEX skills_tags_gin      ON skills USING gin (tags);

-- ── Version history ─────────────────────────────────────────────

CREATE TABLE skill_versions (
    skill_id      UUID NOT NULL REFERENCES skills(id) ON DELETE CASCADE,
    version       INT  NOT NULL,
    body_md       TEXT NOT NULL,
    description   TEXT NOT NULL,
    when_to_use   TEXT,
    -- Back-pointer to the source that produced this version:
    -- {"kind":"agent_brain","agent_id":"..."} etc.
    promoted_from JSONB,
    author_id     UUID REFERENCES users(id) ON DELETE SET NULL,
    approved_by   UUID REFERENCES users(id) ON DELETE SET NULL,
    created_at    TIMESTAMPTZ NOT NULL DEFAULT now(),
    PRIMARY KEY (skill_id, version)
);

-- ── Template-role bindings ──────────────────────────────────────

CREATE TABLE template_role_skills (
    template_id     UUID NOT NULL REFERENCES team_templates(id) ON DELETE CASCADE,
    slot            TEXT NOT NULL,
    skill_id        UUID NOT NULL REFERENCES skills(id) ON DELETE CASCADE,
    -- true → injected at turn start; false → discoverable via MCP
    pin_in_context  BOOLEAN NOT NULL DEFAULT false,
    order_idx       INT NOT NULL DEFAULT 0,
    PRIMARY KEY (template_id, slot, skill_id),
    FOREIGN KEY (template_id, slot)
        REFERENCES template_roles(template_id, slot) ON DELETE CASCADE
);
CREATE INDEX template_role_skills_lookup_idx
    ON template_role_skills (template_id, slot, order_idx);

-- ── Per-agent overrides (level-up) ──────────────────────────────
--
-- Semantics:
--   included = true  → add this skill to the agent's bundle even if
--                      the template didn't include it
--   included = false → remove a template-provided skill for THIS
--                      agent (level-up "prune what never got used")

CREATE TABLE agent_skills_ext (
    agent_id       UUID NOT NULL REFERENCES agents(id) ON DELETE CASCADE,
    skill_id       UUID NOT NULL REFERENCES skills(id) ON DELETE CASCADE,
    included       BOOLEAN NOT NULL DEFAULT true,
    pin_in_context BOOLEAN NOT NULL DEFAULT false,
    added_by       UUID REFERENCES users(id) ON DELETE SET NULL,
    added_reason   TEXT,
    created_at     TIMESTAMPTZ NOT NULL DEFAULT now(),
    PRIMARY KEY (agent_id, skill_id)
);
CREATE INDEX agent_skills_ext_agent_idx ON agent_skills_ext (agent_id);