refactor(threads): dedup maintenance threads by stable key via index

packages/backend/convex/threads.ts

@@ -387,19 +387,20 @@ export const findOpenMaintenanceThread = internalQuery({
   args: {
     spoonId: v.id('spoons'),
     ownerId: v.id('users'),
-    upstreamTo: v.string(),
+    dedupKey: v.string(),
   },
-  handler: async (ctx, { spoonId, ownerId, upstreamTo }) => {
+  handler: async (ctx, { spoonId, ownerId, dedupKey }) => {
     const threads = await ctx.db
       .query('threads')
-      .withIndex('by_spoon', (q) => q.eq('spoonId', spoonId))
+      .withIndex('by_spoon_dedup', (q) =>
+        q.eq('spoonId', spoonId).eq('dedupKey', dedupKey),
+      )
       .order('desc')
       .collect();
     return (
       threads.find(
         (thread) =>
           thread.ownerId === ownerId &&
-          thread.upstreamTo === upstreamTo &&
           !['resolved', 'ignored', 'failed', 'cancelled'].includes(
             thread.status,
           ),
@@ -416,7 +417,8 @@ export const createMaintenanceThread = internalMutation({
     title: v.string(),
     summary: v.string(),
     upstreamFrom: v.optional(v.string()),
-    upstreamTo: v.string(),
+    upstreamTo: v.optional(v.string()),
+    dedupKey: v.string(),
     forkHeadAtCreation: v.optional(v.string()),
     mergeBaseAtCreation: v.optional(v.string()),
     relatedSyncRunId: v.optional(v.id('syncRuns')),
@@ -429,14 +431,15 @@ export const createMaintenanceThread = internalMutation({
     const now = Date.now();
     const existing = await ctx.db
       .query('threads')
-      .withIndex('by_spoon', (q) => q.eq('spoonId', args.spoonId))
+      .withIndex('by_spoon_dedup', (q) =>
+        q.eq('spoonId', args.spoonId).eq('dedupKey', args.dedupKey),
+      )
       .order('desc')
       .collect()
       .then((threads) =>
         threads.find(
           (thread) =>
             thread.ownerId === args.ownerId &&
-            thread.upstreamTo === args.upstreamTo &&
             !['resolved', 'ignored', 'failed', 'cancelled'].includes(
               thread.status,
             ),
@@ -470,6 +473,7 @@ export const createMaintenanceThread = internalMutation({
       priority: args.source === 'merge_conflict' ? 'high' : 'normal',
       upstreamFrom: args.upstreamFrom,
       upstreamTo: args.upstreamTo,
+      dedupKey: args.dedupKey,
       forkHeadAtCreation: args.forkHeadAtCreation,
       mergeBaseAtCreation: args.mergeBaseAtCreation,
       relatedSyncRunId: args.relatedSyncRunId,