Serialize template subtask creation

[cursor]

Changes

• Reduce subtask template creation batch size from 5 to 1 so a single request does not fan out DB work beyond the production Prisma pool limit reported by Sentry (connection_limit=2).
• Add a focused Jest regression test that verifies template subtask batching stays serial.

Testing Criteria

• yarn test src/constants/tasks.test.ts passes and confirms max concurrent handlers is 1.
• yarn lint:check passes.
• yarn tsc was run but fails on pre-existing missing SVG module imports in src/icons/index.ts, unrelated to this change.

Notes

• Root-cause hypothesis: OUT-3964 increased subtask template fan-out to 5, but production Prisma pool limit in the Sentry issue title is 2. Each subtask creation performs multiple DB writes, so applying templates with several subtemplates can queue long enough to hit Prisma's 10s pool timeout.

Impact & Surface Area of Change

• Affects internal and public task creation only when applying a template that has subtask templates.
• Expected behavior change is lower DB pressure and slower but safer subtask-template application for large templates.

  

[linear-code]

OUT-3973

[vercel]

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Project	Deployment	Actions	Updated (UTC)
tasks-app	Ready	Preview, Comment	Jul 11, 2026 7:43pm