Changeset 0.6.0 (#36)

server/database/migrations/006_channels_unify.sql

@@ -0,0 +1,114 @@
+-- ==========================================
+-- Migration 006: Unify Chats → Channels
+-- ==========================================
+-- "Everything is a channel." Merges the separate chats/channels
+-- schema into a single unified channel model.
+--
+-- The old channels/channel_members/channel_messages tables (from 001)
+-- were never populated — safe to drop and rebuild on top of chats.
+-- ==========================================
+
+-- ── 1. Drop unused legacy channel tables ────
+-- These were placeholders from 001; no data, no handlers.
+-- Order matters: drop dependents first.
+
+-- Remove FK references in tool_usage_log before dropping
+ALTER TABLE tool_usage_log DROP CONSTRAINT IF EXISTS tool_usage_log_channel_id_fkey;
+ALTER TABLE tool_usage_log DROP COLUMN IF EXISTS channel_id;
+
+DROP TABLE IF EXISTS channel_messages CASCADE;
+DROP TABLE IF EXISTS channel_members CASCADE;
+DROP TABLE IF EXISTS channels CASCADE;
+
+-- Drop the old trigger (will re-create after rename)
+DROP TRIGGER IF EXISTS channels_updated_at ON channels;
+
+-- ── 2. Rename chats → channels ──────────────
+
+ALTER TABLE chats RENAME TO channels;
+ALTER TABLE chat_messages RENAME TO messages;
+
+-- Rename columns to match new schema
+ALTER TABLE messages RENAME COLUMN chat_id TO channel_id;
+
+-- Rename indexes
+ALTER INDEX IF EXISTS idx_chats_user RENAME TO idx_channels_user;
+ALTER INDEX IF EXISTS idx_chats_updated RENAME TO idx_channels_updated;
+ALTER INDEX IF EXISTS idx_chats_tags RENAME TO idx_channels_tags;
+ALTER INDEX IF EXISTS idx_chat_messages_chat RENAME TO idx_messages_channel;
+
+-- Rename constraints (PK and FK auto-renamed with table on some PG versions,
+-- but let's be explicit for the FK)
+-- Note: PG auto-renames PKs but not FKs or check constraints
+
+-- Rename the updated_at trigger
+DROP TRIGGER IF EXISTS chats_updated_at ON channels;
+CREATE TRIGGER channels_updated_at BEFORE UPDATE ON channels
+    FOR EACH ROW EXECUTE FUNCTION update_updated_at();
+
+-- ── 3. Add channel type + description ───────
+
+ALTER TABLE channels ADD COLUMN IF NOT EXISTS type VARCHAR(20) DEFAULT 'direct';
+ALTER TABLE channels ADD COLUMN IF NOT EXISTS description TEXT;
+
+COMMENT ON COLUMN channels.type IS 'direct=1:1 AI chat, group=multi-model, channel=named persistent';
+
+-- Backfill: all existing rows are 1:1 AI chats
+UPDATE channels SET type = 'direct' WHERE type IS NULL;
+
+-- Index on type for filtered queries
+CREATE INDEX IF NOT EXISTS idx_channels_type ON channels(type);
+
+-- ── 4. Add message tree (parent_id) ─────────
+
+ALTER TABLE messages ADD COLUMN IF NOT EXISTS parent_id UUID REFERENCES messages(id) ON DELETE SET NULL;
+
+CREATE INDEX IF NOT EXISTS idx_messages_parent ON messages(parent_id);
+
+-- Backfill linear parent chains on existing messages.
+-- Each message's parent is the previous message in the same channel (by created_at).
+WITH ordered AS (
+    SELECT id, channel_id, created_at,
+           LAG(id) OVER (PARTITION BY channel_id ORDER BY created_at) AS prev_id
+    FROM messages
+)
+UPDATE messages m
+SET parent_id = o.prev_id
+FROM ordered o
+WHERE m.id = o.id AND o.prev_id IS NOT NULL AND m.parent_id IS NULL;
+
+-- ── 5. Add participant columns on messages ──
+-- Decouples messages from user-only: AI models are participants too.
+
+ALTER TABLE messages ADD COLUMN IF NOT EXISTS participant_type VARCHAR(10) DEFAULT 'user';
+ALTER TABLE messages ADD COLUMN IF NOT EXISTS participant_id VARCHAR(255);
+
+COMMENT ON COLUMN messages.participant_type IS 'user or model';
+COMMENT ON COLUMN messages.participant_id IS 'user UUID or model identifier string';
+
+-- Backfill: user messages get the channel owner's user_id;
+-- assistant messages get the model name as participant_id.
+UPDATE messages m
+SET participant_type = CASE WHEN m.role = 'assistant' THEN 'model' ELSE 'user' END,
+    participant_id = CASE
+        WHEN m.role = 'assistant' THEN COALESCE(m.model, 'unknown')
+        ELSE (SELECT c.user_id::text FROM channels c WHERE c.id = m.channel_id)
+    END
+WHERE m.participant_id IS NULL;
+
+-- ── 6. Update model_routing_log FK ──────────
+
+-- The FK column was named chat_id — rename it
+ALTER TABLE model_routing_log RENAME COLUMN chat_id TO channel_id;
+ALTER INDEX IF EXISTS idx_routing_log_chat RENAME TO idx_routing_log_channel;
+
+-- message_id FK still valid (messages table was renamed, FK follows)
+
+-- ── 7. Update tool_usage_log ────────────────
+-- We already dropped the old channel_id column above.
+-- Re-add it pointing to the unified channels table.
+-- Also rename the old chat_id column.
+
+ALTER TABLE tool_usage_log RENAME COLUMN chat_id TO channel_id;
+-- The FK auto-follows the table rename, but let's be safe:
+-- (chat_id FK pointed to chats(id), which is now channels(id) — PG handles this)