chore: make initial_tasks NULL by default to indicate 'unknown yet'

[jumski]

TL;DR

Changed initial_tasks from hardcoded "1" to NULL for dependent map steps, improving semantic correctness.

What changed?

• Modified the database schema to allow NULL values for initial_tasks in the step_states table
• Added a constraint to ensure initial_tasks is not NULL when a step is started
• Updated SQL functions to:
  • Set initial_tasks = NULL for dependent map steps during flow creation
  • Resolve the NULL value to the actual array length when dependencies complete
  • Prevent steps with NULL initial_tasks from starting
• Moved the implementation plan from pkgs/core/PLAN_use_null_for_map_initial_tasks.md to the root directory
• Updated the PLAN.md to prioritize this change before other map-related work
• Added new tests to verify the NULL behavior works correctly

How to test?

• Run the new test files:
  • pkgs/core/supabase/tests/initial_tasks_null/dependent_maps_null.test.sql
  • pkgs/core/supabase/tests/start_flow/dependent_map_initial_tasks_null.test.sql
• Verify that dependent map steps start with NULL initial_tasks
• Verify that when dependencies complete, NULL is resolved to the correct array length
• Verify that steps cannot start with NULL initial_tasks

Why make this change?

This change improves semantic correctness in the system:

• NULL correctly represents "unknown until dependencies complete"
• The previous approach of using "1" as a placeholder was misleading
• This change makes the code more explicit about the state of map steps
• It's an important foundation for upcoming map features like array distribution and output aggregation

[changeset-bot]

⚠️ No Changeset found

Latest commit: 2b71eb5

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[coderabbitai]

Important

Review skipped

Auto reviews are disabled on this repository.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

✨ Finishing touches

🧪 Generate unit tests

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch 09-16-make-initial-tasks-nullable

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[jumski]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• test: add integration tests for flows with map steps #222
• feat: add task_index attribute to step_task_record and start_tasks function #221
• Fix Orphaned Messages on Run Failure #220
• chore: improve verify-schemas-synced and regenerate-temp-migration #219
• feat: Add .map() Method to Flow DSL for Map Step Support #218
• feat: add Map Step Output Aggregation #217
• feat: enhance start_tasks with conditional input logic and add array handling migration #216
• chore: make initial_tasks NULL by default to indicate 'unknown yet' #215 👈 (View in Graphite)
• feat: implement cascade completion of taskless steps #214
• # 🚀 Task Spawning for Map Steps #213
• feat: add root map step support #209
• feat: add map step type in sql #208
• feat: add map and array steps for parallel processing #207
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.

[nx-cloud]

View your CI Pipeline Execution ↗ for commit 2b71eb5

Command	Status	Duration	Result
nx run-many -t build --projects client,dsl --co...	✅ Succeeded	4s	View ↗
nx affected -t build --configuration=production...	✅ Succeeded	4s	View ↗
nx affected -t lint typecheck test --parallel -...	✅ Succeeded	6m 3s	View ↗

---

☁️ Nx Cloud last updated this comment at 2025-09-16 14:45:42 UTC

[github-actions]

🔍 Preview Deployment: Website

✅ Deployment successful!

🔗 Preview URL: https://pr-215.pgflow.pages.dev

📝 Details:

• Branch: 09-16-make-initial-tasks-nullable
• Commit: 37984a1b528dd6d509925647e148e191948b5fce
• View Logs

_Last updated: _

[github-actions]

🔍 Preview Deployment: Playground

✅ Deployment successful!

🔗 Preview URL: https://pr-215--pgflow-demo.netlify.app

📝 Details:

• Branch: 09-16-make-initial-tasks-nullable
• Commit: 37984a1b528dd6d509925647e148e191948b5fce
• View Logs

_Last updated: _