feat(iter-14): rank promotion banner, WITH RECURSIVE date spine & FIRST_VALUE/LAST_VALUE levels

[martinl5]

Summary

• Rank Promotion Banner — spring-animated maritime toast when XP crosses a career-rank threshold (Graduate Analyst → Senior Analyst → VP → Managing Director)
• Level 76 — Monthly Revenue Completeness Check: first use of WITH RECURSIVE date spine + LEFT JOIN zero-fill
• Level 77 — Fleet Voyage Bookends: FIRST_VALUE + LAST_VALUE with the critical explicit window-frame gotcha

[UI/UX Improvements]

RankPromotionBanner.tsx (new component, wired into GameProvider.tsx):

The career-rank ladder (Graduate Analyst → Senior Analyst → VP, Data & Analytics → Managing Director) has been reachable since iter-7, but crossing a threshold produced no feedback. This PR adds the missing signal.

• Spring entrance animation (stiffness 320, damping 26) slides the card down from 80 px above viewport; exits the same way.
• Gold top accent stripe + deep shadow give depth without obscuring gameplay.
• Rank-specific icon (⚓ / 🧭 / 🏅) spins 720° on entry — one deliberate motion moment, not ambient noise.
• 6-second auto-dismiss with depleting gold countdown bar; dismiss × button and click-anywhere also close it.
• Each rank has bespoke maritime flavour text tied to the SQL skills just demonstrated.
• Detection via useRef tracking previous rank name in GameProvider — fires only when rank name changes after the initial render (no spurious trigger on load).

Implements the "gamification: rank tiers" rotation item.

[Game Design Tweaks]

Level 76 (Expert, difficulty 4) — "Monthly Revenue Completeness Check (WITH RECURSIVE)":

• First WITH RECURSIVE level in the catalog — teaches iterative CTEs as a SQL primitive
• Recursive CTE months(month) seeds at '2024-01', advances via STRFTIME('%Y-%m', DATE(month || '-01', '+1 month')), terminates at '2024-06'
• LEFT JOIN to actual monthly cargo revenue with COALESCE zero-fill and status flag
• Returns 6 rows (all Active — data is complete, proving the guard works)
• Pedagogical point: GROUP BY silently hides zero-activity periods; date spines surface gaps explicitly
• Pattern used in Looker, Redshift/Snowflake time-spine logic, and MAS reporting gap-detection pipelines

Level 77 (Expert, difficulty 4) — "Fleet Voyage Bookends (FIRST_VALUE + LAST_VALUE)":

• Teaches FIRST_VALUE and LAST_VALUE with the window-frame gotcha: LAST_VALUE default frame RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW returns the current row's value, not the partition's last — requires explicit ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING
• Single CTE voyage_data computes all four window expressions together; outer query deduplicates with WHERE rn = 1
• Returns 12 rows — one per vessel. 7 vessels show first_origin ≠ last_origin (routing evolution visible); 5 show matching bookends (consistent homebase)
• Pattern appears in FAANG DS interviews, trading-desk settlement-gap analysis, and logistics routing pipelines

[Database & Code Optimizations]

• LevelUpModal hint map extended with entries for levels 76 and 77; nextHintKey sentinel extended to […, 75, 76, 77]; fallback updated ?? 75 → ?? 77
• MAX_LEVEL auto-derives from levels[levels.length - 1].id (77) — no other touch points
• No new DB tables, seed rows, or indexes

Test Results

• npm ci — ✅ installed (pre-existing vulnerabilities, none introduced)
• npx tsc --noEmit — ✅ 0 errors
• npm test — ✅ 425 tests pass (up from 415 in iter-13; both new levels auto-picked up by determinism invariants suite)

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Project	Deployment	Actions	Updated (UTC)
sqlwak	Ready	Preview, Comment	Jul 13, 2026 5:18pm