feat(aio): add system one boolean judges with shared egress - #103752

This PR is assigned to the backend Python lane. It runs backend Python tests and may merge in parallel with PRs in other lanes.

Cyclomatic complexity above the limit in changed typescript files (10 for production files, 15 for test files). Warn only: worth simplifying when you next touch these functions.

New Python code duplication introduced by this branch. Fails at 70+ tokens in app code, or 150+ tokens when both copies live in test files. Advisory while the gate proves itself: extract a shared helper instead of copying.

New TypeScript code duplication introduced by this branch. Fails at 70+ tokens in app code, or 150+ tokens when both copies live in test files. Advisory while the gate proves itself: extract a shared helper instead of copying.

Uncompressed size of every built .js bundle, compared against the base branch.

Total: 68.82 MiB · 🔺 +4.8 KiB (+0.0%)

_{Posted automatically by build-bundle-size-report · uncompressed bytes from dist-report}

How much code each root ships on the eager path — downloaded and parsed before the surface is interactive. Measured from the esbuild output chunks (post-tree-shake, static imports only); lazy import() / React.lazy chunks are not counted.

🟢 node_modules/monaco-editor/ stays out of src/index.tsx
🟢 src/lib/components/ActivityLog/describers stays out of src/index.tsx
🟢 [object Object] stays out of src/index.tsx
🟢 [object Object] stays out of src/index.tsx
🟢 node_modules/monaco-editor/ stays out of src/index.tsx + src/scenes/App.tsx + src/scenes/bootApp.ts
🟢 src/layout/navigation-3000/navigationLogic.tsx stays out of src/index.tsx + src/scenes/App.tsx + src/scenes/bootApp.ts
🟢 src/scenes/dashboard/dashboardLogic.tsx stays out of src/index.tsx + src/scenes/App.tsx + src/scenes/bootApp.ts
🟢 src/lib/lemon-ui/LemonMarkdown/ stays out of src/index.tsx + src/scenes/App.tsx + src/scenes/bootApp.ts
🟢 src/lib/components/RichContentEditor/ stays out of src/index.tsx + src/scenes/App.tsx + src/scenes/bootApp.ts
🟢 src/lib/components/CodeSnippet/ stays out of src/index.tsx + src/scenes/App.tsx + src/scenes/bootApp.ts
🟢 src/taxonomy/core-filter-definitions-by-group.json stays out of src/index.tsx + src/scenes/App.tsx + src/scenes/bootApp.ts
🟢 node_modules/monaco-editor/ stays out of src/scenes/AuthenticatedShell.tsx
🟢 src/lib/components/ActivityLog/describers stays out of src/scenes/AuthenticatedShell.tsx
🟢 [object Object] stays out of src/scenes/AuthenticatedShell.tsx
🟢 src/scenes/session-recordings/player/sessionRecordingPlayerLogic.ts stays out of src/scenes/AuthenticatedShell.tsx
🟢 [object Object] stays out of src/scenes/AuthenticatedShell.tsx
🟢 [object Object] stays out of src/scenes/AuthenticatedShell.tsx
🟢 [object Object] stays out of src/scenes/AuthenticatedShell.tsx

_{Posted automatically by check-eager-graph · sizes are eager output bytes (shipped, post-tree-shake) from the esbuild metafile · part of #32479}

What the toolbar ships to customer pages, measured from the esbuild output (minified, post-tree-shake). The eager set is the entry plus everything statically imported from it — fetched before any feature runs; deferred chunks load lazily. The eager guardrail is 5.72 MiB. Each output file must also stay below 10 MB, where CloudFront stops compressing it. The module boundary is enforced separately by check-toolbar-graph.

_{Posted automatically by check-toolbar-size · sizes are toolbar output bytes (shipped, post-tree-shake) from the esbuild metafile}

Total size of the built frontend/dist folder (all assets), compared against the base branch.

Total: 943.60 MiB · 🔺 +79.9 KiB (+0.0%)

Built size of each MCP UI app (main.js + styles.css).

All tests passed.

View test results →

🧪 Backend test coverage

Patch coverage — changed backend lines (products + core): ██████████████████░░ 91.0% (1,199 / 1,306)

🤖 Agents: add a test covering the lines above, or note why under "How did you test this code?". Machine-readable gap list: the patch-coverage artifact on this run (gh run download 36490601971 -n patch-coverage), or the coverage-data block at the end of this comment.

Report-only. Patch coverage = changed backend lines covered vs origin/master. Sorted lowest first.
Known gaps: lines covered only by Temporal tests show as uncovered; core line numbers may drift if master changed the same file.

Snapshots: MCP unit test snapshots updated

Changes: 3 snapshots (3 modified, 0 added, 0 deleted)

What this means:

• Snapshots have been automatically updated to match current output

Next steps:

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

Review snapshot changes →

Docs from this PR will be published at posthog.com.

The preview should be ready in about 10 minutes. Open the preview at /handbook/engineering/.

Hobby deployment smoke test passed successfully.

_{Run 36490602770}

Walkthrough

The changes add System One as a provider for boolean evaluations. They add connection configuration, endpoint and response validation, probability-based verdicts, retry and rejection handling, and probability event data. The frontend adds connection settings, separates evaluation models from generative BYOK models, and displays probabilities in evaluation details. Provider schemas, tests, pricing, and internal documentation are also updated.

Security Blast Radius

• inferred — Exposure follows evaluations using a configured connection, not merely connection validation: evaluation-derived content can leave the service for the official provider or a customer-configured compatible endpoint. The documented instance credential shares an account budget, while other endpoint-and-credential combinations receive separate scopes; independent session-level content coverage was not established.

Security Findings and Attack Paths

• inferred — The retained data-exposure finding concerns the new path from customer-derived evaluation input through the service's outbound provider call without an evidenced enforcement point for the documented data-sharing policy. It does not establish that an unobserved external rollout control is absent.

Trust Boundaries and Controls

• observed — The reviewed evaluation adapter revalidates and pins the configured destination when making the actual request, rather than relying solely on the earlier synthetic connection check. The request chain preserves the pinned session and disabled-redirect argument.

Resilience and Maintainability Implications

• observed — Failed connection updates leave the stored configuration unchanged. On terminal evaluation errors, disabling is a team-scoped, transactional, repeat-safe transition; recording the provider-key state is a subsequent activity rather than part of that transaction.

Hardening Proposals

• proposed — Make the documented experimental and customer-data authorization gates enforceable before evaluation content enters outbound egress, and establish their rollout and approval state before launch.
• proposed — Keep URL validation and pinning owned by the shared outbound boundary if additional production callers adopt its configurable System One entrypoint; the reviewed evaluation caller already supplies those controls.