improvement(db): reduce connection saturation and egress hotspots

[waleedlatif1]

Summary

• Reduce postgres-js pool max from 30 → 15 in @sim/db and realtime app (validated against 24h PlanetScale Insights: 3.5 avg fleet concurrency, 25× headroom on steady state, 2.5× under 10× burst)
• Scope workflow_blocks agent query to workspace in MCP refresh + stored routes (eliminates ~88 GB/day egress from cross-tenant scan)
• Project copilot_chats.messages SQL-side in workspace VFS materializer (eliminates ~58 GB/day egress; semantically identical to prior JS-side filter)

Type of Change

• Bug fix

Testing

Tested manually. Validated:

• bun run check:api-validation passes
• bun run type-check passes (no errors)
• SQL projection produces exactly the shape serializeTaskChat consumes
• MCP route filter migrated from JS to SQL is logically equivalent; inArray guarded by existing workflowIds.length === 0 early return

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
docs	Skipped		May 14, 2026 6:31am

[cursor]

PR Summary

Medium Risk
Moderate risk because it changes database connection pooling limits and rewrites query projections/filters (including JSONB SQL), which could impact performance or edge-case data shapes if assumptions differ in production.

Overview
Reduces postgres client pool max from 30 to 15 in both packages/db/db.ts and realtime’s operations.ts to lower connection saturation.

Optimizes MCP endpoints (/api/mcp/servers/[id]/refresh and /api/mcp/tools/stored) by scoping workflow_blocks agent-block reads to the current workspace’s workflow IDs via inArray, removing the prior cross-workspace scan + in-process filtering.

Updates Copilot workspace VFS task materialization to compute messageCount and project a filtered/normalized copilot_chats.messages array in SQL (only user/assistant roles and text contentBlocks), reducing JSON egress while keeping the serialized output shape consistent.

^{Reviewed by Cursor Bugbot for commit 631e60f. Configure here.}

[greptile-apps]

Greptile Summary

This PR addresses connection saturation and egress hotspots through three targeted changes: halving the postgres-js pool max from 30 to 15 in both @sim/db and the realtime app, and pushing two JS-side filters into SQL to eliminate ~146 GB/day of cross-tenant data transfer.

• Pool reduction (packages/db/db.ts, apps/realtime/src/database/operations.ts): max lowered from 30 → 15, validated against 24 h PlanetScale metrics showing ample headroom.
• MCP workspace scoping (refresh/route.ts, stored/route.ts): workflowBlocks query now includes inArray(workflowBlocks.workflowId, workflowIds), eliminating the full-table agent-block scan; both call-sites have an existing workflowIds.length === 0 early return that guards against empty-array SQL issues.
• Copilot VFS SQL projection (workspace-vfs.ts): copilot_chats.messages is now filtered and shaped server-side via an inline jsonb_agg subquery rather than shipping the full column and filtering in JS.

Confidence Score: 5/5

Safe to merge — all three changes are well-scoped optimizations with no behaviour regressions.

Pool reduction is purely a config tuning backed by production metrics. Both MCP workspace-scoping changes move an existing JS filter into SQL with the empty-array edge case correctly handled by pre-existing early returns. The copilot VFS SQL projection preserves pre-PR semantics: role/content operators (->> / ->) are used correctly, and COALESCE guards cover NULL and empty-array column states.

No files require special attention.

Important Files Changed

Filename	Overview
packages/db/db.ts	Pool max reduced from 30 to 15; no logic changes, straightforward config tuning.
apps/realtime/src/database/operations.ts	Pool max reduced from 30 to 15; mirrors the packages/db change, no other modifications.
apps/sim/app/api/mcp/servers/[id]/refresh/route.ts	Workspace filter moved from post-query JS to SQL inArray; empty-array case correctly guarded by existing early return at line 71.
apps/sim/app/api/mcp/tools/stored/route.ts	Same workspace-scoping improvement as the refresh route; workflowIds.length === 0 guard at line 29 prevents empty-array inArray issues.
apps/sim/lib/copilot/vfs/workspace-vfs.ts	Messages column projected SQL-side; role/content extraction uses correct ->> / -> operators; COALESCE guards handle NULL/empty columns safely.

_{Reviews (3): Last reviewed commit: "fix(vfs): guard jsonb_array_elements aga..." | Re-trigger Greptile}

[waleedlatif1]

@greptile

[waleedlatif1]

@cursor review

[waleedlatif1]

@cursor review

[waleedlatif1]

@greptile

[cursor]

✅ Bugbot reviewed your changes and found no new issues!

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^{Reviewed by Cursor Bugbot for commit 631e60f. Configure here.}