[backryun]

Part of #8484. One incomplete producer contract, three diagnostics, zero new.

Root cause

createVirtualAutoCombo("chaos") already emits config.chaos with the enablement flag,
panel metadata, judge model, and tuning values. Its VirtualAutoCombo return type described only
config.auto, so the real factory integration test could not access the chaos configuration
without TS2339 errors.

This adds the existing optional chaos shape to the producer contract and reuses the shared
ChaosTuning type. Runtime values and routing behavior are unchanged; the test remains untouched.

Diagnostics

Measured independently against release/v3.8.49 at 0eeb8f45c:

• TypeScript 6 open-sse diagnostics: 150 → 147
• TypeScript 7.0.2 native diagnostics: 149 → 146
• Full line-number-agnostic error-set diff: 3 fixed, 0 new

With #8809, #8810, #8811, and #8812 included, the cumulative projection is
TS6 134 / TS7 133.

Validation

• npm run typecheck:core
• Auto-combo factory, chaos dispatch, and scoring tests — 70/70 passed
• ESLint on open-sse/services/autoCombo/virtualFactory.ts
• npm run check:file-size
• Prettier and git diff --check

No new test was added because the existing chaosVirtualCombo integration test directly verifies
every field added to the return contract.

Known inherited CI failures

The current base is red on an unrelated React hook dependency and a stale
pack-artifact-policy.test.ts expected list. Both failures were reproduced identically on
release/v3.8.49@0eeb8f45c and #8809's head; this diff touches neither area.