Enforce unique MCP proposal identities

crates/bds-core/migrations/2026-07-22-161429-0000_add_mcp_proposal_entity_status_unique_index/down.sql

@@ -0,0 +1,38 @@
+DROP INDEX mcp_proposals_entity_idx;
+
+CREATE TABLE mcp_proposals_old (
+    id TEXT PRIMARY KEY NOT NULL,
+    project_id TEXT NOT NULL REFERENCES projects(id) ON DELETE CASCADE,
+    kind TEXT NOT NULL CHECK (kind IN (
+        'draft_post',
+        'propose_script',
+        'propose_template',
+        'propose_media_translation',
+        'propose_media_metadata',
+        'propose_post_metadata'
+    )),
+    status TEXT NOT NULL DEFAULT 'pending' CHECK (status IN (
+        'pending', 'executing', 'accepted', 'rejected', 'expired'
+    )),
+    entity_id TEXT,
+    data TEXT NOT NULL,
+    result TEXT,
+    created_at BIGINT NOT NULL,
+    expires_at BIGINT NOT NULL,
+    resolved_at BIGINT
+);
+
+INSERT INTO mcp_proposals_old (
+    id, project_id, kind, status, entity_id, data, result,
+    created_at, expires_at, resolved_at
+)
+SELECT
+    id, project_id, kind, status, entity_id, data, result,
+    created_at, expires_at, resolved_at
+FROM mcp_proposals;
+
+DROP TABLE mcp_proposals;
+ALTER TABLE mcp_proposals_old RENAME TO mcp_proposals;
+
+CREATE INDEX mcp_proposals_project_status_idx
+    ON mcp_proposals(project_id, status, created_at);

crates/bds-core/migrations/2026-07-22-161429-0000_add_mcp_proposal_entity_status_unique_index/up.sql

@@ -0,0 +1,55 @@
+CREATE TABLE mcp_proposals_new (
+    id TEXT PRIMARY KEY NOT NULL,
+    project_id TEXT NOT NULL REFERENCES projects(id) ON DELETE CASCADE,
+    kind TEXT NOT NULL CHECK (kind IN (
+        'draft_post',
+        'propose_script',
+        'propose_template',
+        'propose_media_translation',
+        'propose_media_metadata',
+        'propose_post_metadata'
+    )),
+    status TEXT NOT NULL DEFAULT 'pending' CHECK (status IN (
+        'pending', 'executing', 'accepted', 'rejected', 'expired'
+    )),
+    entity_id TEXT NOT NULL,
+    data TEXT NOT NULL,
+    result TEXT,
+    created_at BIGINT NOT NULL,
+    expires_at BIGINT NOT NULL,
+    resolved_at BIGINT
+);
+
+INSERT INTO mcp_proposals_new (
+    id, project_id, kind, status, entity_id, data, result,
+    created_at, expires_at, resolved_at
+)
+SELECT
+    id, project_id, kind, status, COALESCE(entity_id, id), data, result,
+    created_at, expires_at, resolved_at
+FROM mcp_proposals;
+
+DROP TABLE mcp_proposals;
+ALTER TABLE mcp_proposals_new RENAME TO mcp_proposals;
+
+-- Keep the newest record if a pre-migration database already contains an
+-- invalid duplicate. NULL-backed proposals were assigned their own IDs above
+-- and therefore remain distinct.
+DELETE FROM mcp_proposals AS duplicate
+WHERE EXISTS (
+    SELECT 1
+    FROM mcp_proposals AS keeper
+    WHERE keeper.kind = duplicate.kind
+      AND keeper.entity_id = duplicate.entity_id
+      AND keeper.status = duplicate.status
+      AND (
+          keeper.created_at > duplicate.created_at
+          OR (keeper.created_at = duplicate.created_at AND keeper.id > duplicate.id)
+      )
+);
+
+CREATE INDEX mcp_proposals_project_status_idx
+    ON mcp_proposals(project_id, status, created_at);
+
+CREATE UNIQUE INDEX mcp_proposals_entity_idx
+    ON mcp_proposals(kind, entity_id, status);