feat(embeddings): add embedding model support and related changes

* Introduced EmbeddingModel method in Client and Provider interfaces
* Updated InsertThought and SearchThoughts methods to handle embedding models
* Created embeddings table and updated match_thoughts function for model filtering
* Removed embedding column from thoughts table
* Adjusted permissions for new embeddings table

migrations/006_rls_and_grants.sql

@@ -1,5 +0,0 @@
--- Grant these permissions to the database role used by the application.
--- Replace amcs_user with the actual role in your deployment before applying.
-grant select, insert, update, delete on table public.thoughts to amcs_user;
-grant select, insert, update, delete on table public.projects to amcs_user;
-grant select, insert, update, delete on table public.thought_links to amcs_user;

migrations/007_embeddings_table.sql

@@ -0,0 +1,16 @@
+create table if not exists embeddings (
+  id        bigserial   primary key,
+  guid      uuid        not null default gen_random_uuid(),
+  thought_id uuid       not null references thoughts(id) on delete cascade,
+  model     text        not null,
+  dim       int         not null,
+  embedding vector      not null,
+  created_at timestamptz default now(),
+  updated_at timestamptz default now(),
+  constraint embeddings_guid_unique          unique (guid),
+  constraint embeddings_thought_model_unique unique (thought_id, model)
+);
+
+create index if not exists embeddings_thought_id_idx on embeddings (thought_id);
+
+alter table thoughts drop column if exists embedding;

migrations/008_update_match_thoughts.sql

@@ -0,0 +1,34 @@
+create or replace function match_thoughts(
+  query_embedding  vector,
+  match_threshold  float   default 0.7,
+  match_count      int     default 10,
+  filter           jsonb   default '{}'::jsonb,
+  embedding_model  text    default ''
+)
+returns table (
+  id          uuid,
+  content     text,
+  metadata    jsonb,
+  similarity  float,
+  created_at  timestamptz
+)
+language plpgsql
+as $$
+begin
+  return query
+  select
+    t.id,
+    t.content,
+    t.metadata,
+    1 - (e.embedding <=> query_embedding) as similarity,
+    t.created_at
+  from thoughts t
+  join embeddings e on e.thought_id = t.id
+  where 1 - (e.embedding <=> query_embedding) > match_threshold
+    and t.archived_at is null
+    and (embedding_model = '' or e.model = embedding_model)
+    and (filter = '{}'::jsonb or t.metadata @> filter)
+  order by e.embedding <=> query_embedding
+  limit match_count;
+end;
+$$;

migrations/009_rls_and_grants.sql

@@ -0,0 +1,7 @@
+-- Grant these permissions to the database role used by the application.
+-- Replace amcs_user with the actual role in your deployment before applying.
+grant ALL ON TABLE public.thoughts to amcs;
+grant ALL ON TABLE public.projects to amcs;
+grant ALL ON TABLE public.thought_links to amcs;
+grant ALL ON TABLE public.embeddings to amcs;
+GRANT USAGE, SELECT ON ALL SEQUENCES IN SCHEMA public TO amcs;