Remove legacy migration-based flow compilation before the queue-routing release

[jumski]

Summary

Remove the legacy migration-based flow compiler after #650 and #651 are implemented and validated, but before their first stable release.

Worker startup becomes the only supported deployment path for flow definitions. During #650 and #651, leave the legacy path unchanged and do not extend it with queue mode, step routes, aliases, or other deployment metadata.

This is a pre-release cleanup for #653, not a prerequisite for implementing queue identity or private per-step queues.

Why remove the complete path

The legacy workflow has four coupled surfaces:

compileFlow()
  -> ControlPlane
  -> pgflow compile
  -> generated flow-definition migration

Keeping it for new deployment metadata would require a second implementation of queue-mode and route validation. Removing only ControlPlane would break pgflow compile. Remove the complete legacy unit instead.

Scheduling

#650 queue identity
  -> #651 private per-step queues
  -> downstream validation
  -> #647 legacy compiler removal
  -> stable queue-routing release

Do not make #650 or #651 wait for this cleanup. Do not publish the permanent dual-path support matrix either.

Remove

pkgs/cli

• Delete pgflow compile and its tests.
• Stop creating supabase/functions/pgflow/ during installation.
• Remove compile-command output, options, and current documentation.

pkgs/edge-worker

• Delete ControlPlane, its public export, server code, fixtures, and tests.
• Remove compilation: false; every flow worker compiles or verifies its definition during startup.
• Remove compilation.allowDataLoss; remote startup never authorizes destructive recompilation.

pkgs/dsl

• Delete the public SQL-text compileFlow() helper, export, and tests.
• Delete TypeScript shape-comparison helpers that have no caller after ControlPlane removal.
• Keep flow-shape extraction used by worker startup.

Documentation and examples

• Remove the installed and demo ControlPlane functions.
• Redirect current manual-compilation, Compile API, and ControlPlane pages to startup compilation or the migration notice.
• Remove migration-based flow compilation from current examples, package READMEs, architecture guides, navigation, and generated indexes.
• Keep historical release-news pages intact while marking removed APIs as obsolete in current versions.

Behavior after removal

missing concrete flow  -> compile during worker startup
matching flow          -> verify and start
local mismatch         -> use the existing automatic local recompilation behavior
remote mismatch        -> fail without deleting data; deploy a new concrete slug

A structural or semantic production change uses a new concrete slug:

const greetUserV2 = new Flow({ slug: 'greetUserV2' })

Startup shape verification cannot detect handler-code or TypeScript contract changes. The versioning guide must continue to require a new slug for those changes.

Preserve

• Preserve current local same-slug hot reload and destructive recompilation behavior.
• Preserve the existing SQL startup compiler, flow-shape extraction, and concrete-slug advisory lock.
• Preserve create_flow() and add_step() as database building blocks used by startup compilation.
• Preserve existing generated migrations as ordinary historical SQL in user repositories.
• Preserve the production enable-fence guidance from Document the worker-function enable fence for production deployments #654.

Migration requirements

PostgreSQL keeps overloads with different argument lists. The migration must explicitly remove the production data-loss entry point:

DROP FUNCTION pgflow.ensure_flow_compiled(text, jsonb, boolean);

Then create or keep the intended signature without allow_data_loss, and regenerate database types.

The migration notice must tell existing users to:

1. Remove supabase/functions/pgflow/ and any matching function configuration.
2. Remove pgflow compile from scripts and CI.
3. Remove compilation: false and compilation.allowDataLoss from worker configuration.
4. Make each worker import its complete flow definition.
5. Keep existing generated migration files as migration history.

Acceptance criteria

• Persist physical queue identity for flow tasks #650 and Add private per-step queues with typed step workers #651 implementation plus downstream validation finish before this cleanup starts.
• ControlPlane code, exports, templates, demo functions, tests, and current docs are removed.
• pgflow compile, its tests, options, installation output, and current docs are removed.
• Public SQL-text compileFlow() and orphaned TypeScript-only compiler helpers are removed.
• Worker startup is the only supported owner of flow compilation and verification.
• compilation: false and compilation.allowDataLoss are rejected by the type system and runtime.
• The three-argument ensure_flow_compiled(text, jsonb, boolean) overload is absent after migration.
• Production mismatches fail without deleting data.
• Existing automatic local recompilation behavior remains covered and unchanged.
• Current versioning docs require a new concrete slug for structural and undetectable semantic changes.
• Existing-user migration instructions cover ControlPlane files, configuration, scripts, worker imports, and historical migrations.
• Release notes identify every removed public surface.
• The stable Persist physical queue identity for flow tasks #650 + Add private per-step queues with typed step workers #651 release contains no migration-based flow compiler.

Out of scope

• Worker drain or quiescence redesign.
• Worker restart-state or worker_functions.enabled changes.
• Startup-failure or shape-mismatch persistence.
• Stable aliases.
• Per-step queue implementation.
• Custom or shared queues.
• Changes to flow-shape semantics.