feat(data-warehouse): add facade and route consumers through it

[Gilbert09]

Problem

Phase 2 isolates data_warehouse behind a facade. The structural prereqs landed in #66128; this PR adds the facade itself and routes external consumers through it. Critically, it resolves the warehouse_sources ↔ data_warehouse cycle: warehouse_sources (isolated in Phase 1) imports data_warehouse internals (logic.data_load, s3, the direct-SQL constants, webhook consumer) — those now go through data_warehouse's facade.

Changes

• Facade submodules (backend/facade/), split by import weight so setup-path consumers stay light:
  • sources.py — direct-SQL option constants (consumed by the setup-path warehouse_sources table model).
  • models.py — ExternalDataSourceRevenueAnalyticsConfig.
  • hogql.py — get_warehouse_sync_warnings (the HogQL database builder, setup-adjacent).
  • tasks.py — the beat-scheduled digest catch-up task.
  • dags.py — the managed_viewset_sync Dagster asset module (the root dags/ channel the scan can't see).
  • api.py — the heavy operational surface (temporal schedule/workflow management, S3 helpers, schema reconciliation, job-status updates, webhook ingestion). Off the django.setup() path; its consumers are the temporal workers / import pipeline.
• Consumer sweep — 43 files (warehouse_sources pipeline, posthog/temporal, data_modeling, endpoints, signals, hogql, dags, admin) repointed off data_warehouse internals onto the facade. Identity-preserving.
• Boundary — data_warehouse added to the canonical [[interfaces]] block (tach check --interfaces now enforces facade-only access) + a small legacy-leak for the test helpers core still imports.

Deferred (future Phase 2 PRs)

• Presentation wave — the 16 views keep their import-linter allowances (auto-added by the structural move) and still reach internals; thinning them to use the facade is the next PR.
• Contracts — the external surface here is operational wiring (re-exports), so facade/api.py is re-exports, not model→contract functions (product:lint notes this as a non-blocking warning in lenient mode). Contract-data functions + contracts.py come with the presentation wave.
• The test-helper legacy-leak shrinks when those fixtures relocate; backend:contract-check is the final flip once all leaks are gone.

How did you test this code?

Automated, run locally:

• tach check --dependencies --interfaces → All modules validated (data_warehouse enforced as an interface; the Dagster channel rerouted through facade.dags).
• lint-imports → presentation contract KEPT.
• hogli product:lint data_warehouse → exit 0 (expected lenient-mode warnings: legacy-leak + re-export facade).
• Startup import-budget → pass (the light/heavy facade split keeps table.py/database.py off the heavy temporal/s3 path).
• ruff + py_compile clean on all 52 changed files.

Behavioral product tests run in CI (the sweep is identity-preserving).

Docs update

No user-facing docs changes.

[assign-reviewers-posthog]

👀 Auto-assigned reviewers

These soft owners were skipped because they only have minor changes here. Nothing blocks merge, so self-assign if you'd like a look:

• @PostHog/team-self-driving (products/signals/**)
• @PostHog/team-data-tools (posthog/hogql/**)

Soft owners come from CODEOWNERS-soft and each product's product.yaml. Generated files and lockfiles are ignored when deciding ownership.

[greptile-apps]

_{Reviews (1): Last reviewed commit: "feat(data-warehouse): add facade and enf..." | Re-trigger Greptile}

[github-actions]

🎭 Playwright report · View test results →

⚠️ 1 flaky test:

• View persons list, navigate to detail, and browse tabs (chromium)

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[tests-posthog]

Query snapshots: Backend query snapshots updated

Changes: 1 snapshots (1 modified, 0 added, 0 deleted)

What this means:

• Query snapshots have been automatically updated to match current output
• These changes reflect modifications to database queries or schema

Next steps:

• Review the query changes to ensure they're intentional
• If unexpected, investigate what caused the query to change

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