feat(api,ui): showcase advanced seed config and scope selection (#409)

[w7-mgfcode]

Summary

Implements showcase-completion E3 #409 (Parallel after Foundation E1 #407, umbrella #406): an allow-listed nested seed-override contract, a store/product focus-pair selector, and replay-verbatim persistence of both into the E1 workspace story slots.

Backend

• app/shared/seeder/overrides.py (NEW) — SeederOverrides: 7 curated knobs (stores, products, window_days, sparsity, promotion_intensity, stockout_intensity, noise_sigma), ConfigDict(strict=True, extra="forbid") — an unknown knob is a 422 (umbrella risk-1 mitigation, machine-enforced).
• POST /seeder/generate — additive Optional overrides object; _apply_seed_overrides applied LAST in _build_config_from_params (wins over the scalar stores/products/sparsity); dataclasses.replace preserves preset character (sparse gaps, region/category lists). Absent = byte-identical (regression-tested).
• DemoRunRequest — additive seed_overrides + user_scope with two cross-field validators: overrides require skip_seed=false; window_days rejected on the calendar-pinned holiday_rush; {} normalizes to None.
• Pipeline — step_seed forwards overrides verbatim and echoes effective dims + overrides_applied; step_status validates a user_scope pair via /dimensions/*/{id}, adopts it ("(user-selected)"), or WARNS + falls back to discovery on a dangling pair (replay of a reset=true workspace can never hard-fail).
• Workspace — create_workspace records both story slots (sparse JSON / NULL, inside the warn-and-continue try); slots exposed on WorkspaceListItem (replay reads list rows; Detail inherits).

Frontend

• SeedConfigPanel (collapsible 7-knob panel, gated on Re-seed first, holiday_rush window lock, NaN-WAPE caveat badge, live summary) + ScopeSelector (live /dimensions dropdowns + preview card with seeded window).
• buildReplayRequest extended — replay re-submits recorded seed_overrides/user_scope verbatim; legacy rows stay byte-identical. Load repopulates panel + selector; Reset tick clears the scope (ids re-issue); Re-seed untick clears overrides.

Docs

• API_CONTRACTS (seeder/demo/WS/workspaces rows), RUNBOOKS (showcase incident 29 + workspace-section scope update), DOMAIN_MODEL (authoritative slot schemas, requested-vs-effective grain).

ZERO migrations (E1 #407 owns the schema); no new endpoints; all changes additive.

Test plan

• Backend gates: ruff + format + mypy --strict + pyright --strict + 2045 unit tests
• Frontend: pnpm lint + 420 vitest; no new tsc -b errors in touched files
• Integration (fresh DB): workspace slot persistence, demo+seeder slices, new e2e test_demo_replay_preserves_seed_overrides_and_scope (replay-verbatim slots + dangling-scope warn-fallback)
• Real-browser dogfood (Playwright/Chromium): panel gating/clearing, holiday_rush window lock, Reset scope-clear caveat, overridden 8×20 keep-run green with truthful seed/status cards, panel Replay through the confirm dialog → identical slots + replayed_from_workspace_id lineage

Closes #409

[sourcery-ai]

Sorry @w7-mgfcode, you have reached your weekly rate limit of 500000 diff characters.

Please try again later or upgrade to continue using Sourcery

[coderabbitai]

Important

Review skipped

Auto reviews are disabled on base/target branches other than the default branch.

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.

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 0464697f-31e3-4544-82c7-4b6604414282

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

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/showcase-completion-e3-seed-config-scope

---

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.}